0001564590-21-009946 | 10-K | XBRL Viewer

Year Ended

December 31,

2019

Expected volatility

Risk-free interest rate

Dividend yield

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Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Trading Symbol	KOD
Entity Registrant Name	KODIAK SCIENCES INC.
Entity Central Index Key	0001468748
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity File Number	001-38682
Entity Tax Identification Number	27-0476525
Entity Address, Address Line One	1200 Page Mill Road
Entity Address, City or Town	Palo Alto
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94304
City Area Code	650
Local Phone Number	281-0850
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Document Annual Report	true
Document Transition Report	false
Title of 12(b) Security	Common stock, par value $0.0001
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation Flag	true
Entity Common Stock, Shares Outstanding		51,162,424
Entity Public Float			$ 1.6
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive Proxy Statement relating to the 2021 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. The proxy statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2020.

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 944,396	$ 211,797
Marketable securities	24,578	124,684
Prepaid expenses and other current assets	3,031	2,749
Total current assets	972,005	339,230
Marketable securities		11,696
Restricted cash	6,324	140
Property and equipment, net	5,136	996
Operating lease right-of-use asset	73,672	1,790
Other assets	10,210	5,014
Total assets	1,067,347	358,866
Current liabilities:
Accounts payable	8,646	2,619
Accrued and other current liabilities	20,402	8,658
Operating lease liability	2,374	434
Total current liabilities	31,422	11,711
Operating lease liability, net of current portion	75,028	1,501
Liability related to sale of future royalties	99,890
Other liabilities	256	295
Total liabilities	206,596	13,507
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized; 0 shares issued and outstanding at December 31, 2020 and 2019
Common stock, $0.0001 par value, 490,000,000 shares authorized at December 31, 2020 and 2019; 51,112,302 and 44,413,404 shares issued and outstanding at December 31, 2020 and 2019, respectively	5	5
Additional paid-in capital	1,151,920	503,475
Accumulated other comprehensive income	53	10
Accumulated deficit	(291,227)	(158,131)
Total stockholders’ equity	860,751	345,359
Total liabilities and stockholders’ equity	$ 1,067,347	$ 358,866

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	490,000,000	490,000,000
Common stock, shares issued	51,112,302	44,413,404
Common stock, shares outstanding	51,112,302	44,413,404

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating expenses
Research and development	$ 107,389	$ 37,506	$ 18,793
General and administrative	28,618	11,684	7,581
Total operating expenses	136,007	49,190	26,374
Loss from operations	(136,007)	(49,190)	(26,374)
Interest income	2,902	1,568	617
Interest expense (includes $nil, $nil and $3,030 attributable to related parties for the years ended December 31, 2020, 2019 and 2018, respectively)	(25)	(8)	(5,519)
Other income (expense), net (includes $49, $nil, and $2,736 expenses attributable to related parties for the years ended December 31, 2020, 2019, and 2018, respectively)	34	265	(4,688)
Loss on extinguishment of debt (includes $1,587 attributable to related parties for the year ended December 31, 2018)			(5,479)
Net loss	$ (133,096)	$ (47,365)	$ (41,443)
Net loss per common share, basic and diluted	$ (2.91)	$ (1.25)	$ (2.77)
Weighted-average common shares outstanding used in computing net loss per common share, basic and diluted	45,741,845	37,853,616	14,976,515
Other comprehensive income
Change in unrealized gains related to available-for-sale debt securities, net of tax	$ 43	$ 10
Total other comprehensive income	43	10
Comprehensive loss	$ (133,053)	$ (47,355)	$ (41,443)

Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018
Income Statement [Abstract]
Interest expense attributable to related parties		$ 3,030
Other income (expense) attributable to related parties	$ 49	2,736
Loss on extinguishment of debt attributable to related parties		$ 1,587

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning Balance at Dec. 31, 2017	$ (68,738)		$ 1	$ 584		$ (69,323)
Redeemable convertible preferred stock, shares outstanding, beginning balance at Dec. 31, 2017		12,385,154
Redeemable convertible preferred stock, beginning balance at Dec. 31, 2017		$ 50,017
Beginning balance, shares at Dec. 31, 2017			7,936,434
Issuance of common stock upon exercise of stock options	49			49
Issuance of common stock upon exercise of stock options, shares			47,800
Issuance of restricted stock awards, shares			27,500
Conversion of redeemable convertible preferred stock into common stock	50,017		$ 1	50,016
Conversion of redeemable convertible preferred stock into common stock, shares		(12,385,154)
Conversion of redeemable convertible preferred stock into common stock		$ (50,017)
Conversion of redeemable convertible preferred stock into common stock, shares			12,385,154
Conversion of redeemable convertible preferred stock warrants into common stock warrants	5,000			5,000
Issuance of common stock upon exercise of common stock warrants, shares			100,000
Conversion of 2017 and 2018 convertible notes into common stock	55,733		$ 1	55,732
Conversion of 2017 and 2018 convertible notes into common stock, shares			6,932,969
Issuance of common stock in connection with initial public offering/follow-on offering, net of offering costs	83,459		$ 1	83,458
Issuance of common stock in connection with initial public offering/follow-on offering, net of offering costs, shares			9,400,000
Stock-based compensation expense	2,756			2,756
Net loss	(41,443)					(41,443)
Ending Balance at Dec. 31, 2018	86,833		$ 4	197,595		(110,766)
Ending balance, shares at Dec. 31, 2018			36,829,857
Issuance of common stock upon exercise of stock options	2,287			2,287
Issuance of common stock upon exercise of stock options, shares			662,079
Vesting of restricted stock units, net of taxes withheld	(132)			(132)
Vesting of restricted stock units, net of taxes withheld, shares			21,467
Issuance of common stock upon exercise of common stock warrants, shares			1
Issuance of common stock in connection with initial public offering/follow-on offering, net of offering costs	297,616		$ 1	297,615
Issuance of common stock in connection with initial public offering/follow-on offering, net of offering costs, shares			6,900,000
Stock-based compensation expense	6,110			6,110
Other comprehensive income	10				$ 10
Net loss	(47,365)					(47,365)
Ending Balance at Dec. 31, 2019	345,359		$ 5	503,475	10	(158,131)
Ending balance, shares at Dec. 31, 2019			44,413,404
Issuance of common stock upon exercise of stock options	6,248			6,248
Issuance of common stock upon exercise of stock options, shares			704,675
Vesting of restricted stock units, net of taxes withheld	(487)			(487)
Vesting of restricted stock units, net of taxes withheld, shares			22,001
Issuance of common stock in connection with initial public offering/follow-on offering, net of offering costs	612,016			612,016
Issuance of common stock in connection with initial public offering/follow-on offering, net of offering costs, shares			5,972,222
Stock-based compensation expense	30,668			30,668
Other comprehensive income	43				43
Net loss	(133,096)					(133,096)
Ending Balance at Dec. 31, 2020	$ 860,751		$ 5	$ 1,151,920	$ 53	$ (291,227)
Ending balance, shares at Dec. 31, 2020			51,112,302

Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Stockholders Equity [Abstract]
Offering costs with respect to issuance of common stock in connection with initial public offering/follow-on offering	$ 32,984	$ 19,784	$ 10,542

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (133,096)	$ (47,365)	$ (41,443)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	477	538	490
Non-cash interest expense and amortization of debt discount and issuance cost	0	0	5,482
Change in fair value of redeemable convertible preferred stock warrant liability	0	0	2,700
Change in fair value of derivative instrument	0	0	1,988
Extinguishment of debt			5,479
Stock-based compensation	30,668	6,110	2,665
Amortization (accretion) of premium (discount) on marketable securities	(51)	(241)
Amortization of operating lease right-of-use asset	3,731	373
Amortization of issuance costs	49	0	0
Changes in assets and liabilities:
Prepaid expense and other current assets	(218)	(168)	(1,995)
Other assets	(1,814)	(4,511)	0
Accounts payable	5,224	1,569	(2,323)
Accrued and other current liabilities	11,748	4,932	(2,105)
Operating lease liability	(146)	(383)
Other liabilities	0	0	31
Net cash used in operating activities	(83,428)	(39,146)	(29,031)
Cash flows from investing activities
Purchase of property and equipment	(3,814)	(437)	(78)
Deposits on property and equipment	(3,184)		(503)
Purchases of marketable securities	(86,317)	(150,961)
Maturities of marketable securities	198,149	14,400
Net cash provided by (used in) investing activities	104,834	(136,998)	(581)
Cash flows from financing activities
Proceeds from issuance of common stock in connection with offering, net of offering costs	612,016	297,616	83,755
Proceeds from issuance of common stock upon option exercise	6,248	2,287	49
Payments for restricted stock units, net of taxes withheld	(487)	(132)
Proceeds from issuance of convertible notes (includes $9,560 from related parties for the years ended December 31, 2018)			33,000
Debt issuance cost	0	0	(140)
Proceeds from sale of future royalties, net of issuance costs	99,643	0	0
Principal payments of capital lease	(5)	(48)	(108)
Principal payments of tenant improvement allowance payable	(38)	(36)	(85)
Net cash provided by financing activities	717,377	299,687	116,471
Net increase in cash, cash equivalents and restricted cash	738,783	123,543	86,859
Cash, cash equivalents and restricted cash, at beginning of year	211,937	88,394	1,535
Cash, cash equivalents and restricted cash, at end of year	950,720	211,937	88,394
Reconciliation of cash, cash equivalents and restricted cash to consolidated balance sheets
Cash and cash equivalents	944,396	211,797	88,254
Restricted cash	6,324	140	140
Cash, cash equivalents and restricted cash, at end of year	950,720	211,937	88,394
Supplemental cash flow information:
Cash paid for interest	25	8	19
Supplemental disclosures of non-cash investing and financing information:
Operating lease right-of-use asset obtained in exchange for operating lease liability	75,614	2,163
Purchase of property and equipment under accounts payable	803	0	0
Unpaid offering costs	238	459	205
Offering costs paid in restricted stock awards	0	0	91
Derivative instrument related to convertible notes	$ 0	$ 0	$ 6,603

Consolidated Statements of Cash Flows (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Statement Of Cash Flows [Abstract]
Proceeds from issuance of convertible notes	$ 9,560

The Company

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

The Company

1. The Company

Kodiak Sciences Inc. (the “Company”) is a clinical stage biopharmaceutical company specializing in novel therapeutics to treat high-prevalence ophthalmic diseases. The Company devotes substantially all of its time and efforts to performing research and development, raising capital and recruiting personnel.

Initial Public Offering

In 2018, the Company sold and issued 9,400,000 shares of common stock, including the underwriters’ full exercise of their over-allotment option, at a price to the public of $10.00 per share for gross proceeds of $94.0 million. The aggregate net proceeds to the Company from the IPO, inclusive of the partial over-allotment option exercise, were $83.5 million after deducting underwriting discounts and commissions and other offering costs.

Upon the closing of the IPO, all convertible preferred shares then outstanding automatically converted into 12,385,154 shares of common stock, 500,000 redeemable convertible preferred stock warrants automatically converted into common stock warrants and 100,000 of such warrants were exercised immediately following the closing of the IPO. The 2017 convertible notes converted into 2,637,292 shares of common stock and the 2018 convertible notes converted into 4,295,677 shares of common stock upon closing of the IPO. In connection with the IPO, the Company amended and restated its certificate of incorporation and bylaws.

Follow-On Offering

In December 2019, the Company sold and issued 6,900,000 shares of common stock, including the underwriters’ full exercise of their over-allotment option, at a price to the public of $46.00 per share for gross proceeds of $317.4 million. The aggregate net proceeds to the Company from the follow-on offering were $297.6 million after deducting underwriting discounts and commissions and other offering costs.

In November 2020, the Company sold and issued 5,972,222 shares of common stock, including the underwriters’ full exercise of their over-allotment option, at a price to the public of $108.00 per share for gross proceeds of $645.0 million. The aggregate net proceeds to the Company from the follow-on offering were $612.0 million after deducting underwriting discounts and commissions and other offering costs.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”).

Reclassification

Certain prior period amounts in the consolidated financial statements have been reclassified to conform to the current period presentation.

Principles of Consolidation

The consolidated financial statements include the Company’s accounts and the accounts of Kodiak Sciences Financing Corporation and Kodiak Sciences China, the Company’s direct wholly owned subsidiaries, incorporated in the United States and Cayman Islands, respectively, and Kodiak Sciences GmbH and Kodiak Sciences Valais GmbH, the Company’s indirect wholly owned subsidiaries, both incorporated in Switzerland. All intercompany accounts and transactions have been eliminated. The functional and reporting currency of the Company and its subsidiaries is the U.S. dollar. The aggregate foreign currency transaction loss included in determining net loss was $0.3 million, less than $0.1 million and $0.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Segments

The Company operates and manages its business as one reportable and operating segment, which is the business of research and development of drugs for ophthalmic diseases. The chief operating decision maker reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and expenses during the reporting period. The impact of the ongoing COVID-19 pandemic continues to evolve. As a result, certain estimates and assumptions required increased judgment and carried a higher degree of variability and volatility, including but not limited to, the fair value of marketable securities, performance-based equity awards, and research and development accruals. As events continue to unfold and additional information becomes available, these estimates may change materially in future periods. Actual results could differ from those estimates.

Risk and Uncertainties

In March 2020, the World Health Organization declared a pandemic due to the global COVID-19 outbreak. The significant uncertainties caused by the ongoing COVID-19 pandemic may negatively impact the Company’s operations, liquidity, and capital resources and will depend on certain evolving developments, including the duration and spread of the outbreak, regulatory and private sector responses and the impact on employees and vendors including supply chain and clinical partners, all of which are uncertain and cannot be predicted. During this pandemic, the Company continues to work closely with clinical sites towards maximal patient safety and the lowest number of missed visits and study discontinuations. The Company has taken and continues to take proactive measures to maintain the integrity of its ongoing clinical studies. Despite these efforts, the ongoing COVID-19 pandemic could significantly impact clinical trial enrollment and completion of its clinical studies. The Company will continue to monitor the COVID-19 situation and its impact on the ability to continue the development of, and seek regulatory approvals for, the Company’s product candidates, and begin to commercialize any approved products.

The Company’s future results of operations involve a number of risks and uncertainties common to clinical-stage companies in the biotechnology industry. The Company’s product candidates are in development and the Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biotechnology companies. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential drug candidates, uncertainty of market acceptance of any of the Company’s product candidates that receive regulatory approval, competition from new technological innovations, substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals, contract manufacturer and research organizations, and other suppliers.

Products developed by the Company require approvals from the U.S. Food and Drug Administration (“FDA”) or other international regulatory agencies prior to commercial sales. There can be no assurance that any of the Company’s product candidates will receive the necessary approvals. If the Company is denied approval, approval is delayed or the Company is unable to maintain approvals, it could have a materially adverse impact on the Company. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales.

The Company expects to incur substantial operating losses for the next several years and will need to obtain additional financing in order to complete clinical trials and launch and commercialize any product candidates for which it receives regulatory approval. There can be no assurance that such financing will be available or will be on terms acceptable by the Company.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and marketable securities. As of December 31, 2020 and 2019, cash, cash equivalents and marketable securities were invested primarily in money market funds, overnight repurchase agreements, U.S. treasury securities, commercial paper and corporate notes through highly rated financial institutions. Investments are restricted, in accordance with the Company’s investment policy, to a concentration limit per issuer or sector.

Cash and Cash Equivalents

The Company considers all highly liquid investments with stated maturities of three months or less at the date of purchase to be cash equivalents.

Marketable Securities

The Company invests excess cash balances in marketable securities. The investments in marketable securities are classified as either held-to-maturity or available-for-sale based on facts and circumstances present at the time of purchase. Marketable securities with a remaining maturity date greater than one year are classified as non-current. The Company’s marketable securities consist of U.S. treasury securities, commercial paper, and corporate bonds. Marketable securities are carried at fair value with the unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase of marketable debt securities is amortized and/or accreted to other income (expense), net over the life of the instrument. Realized gains and losses are determined using the specific identification method and are included in other income (expense), net.

If any adjustment to fair value reflects a decline in value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other-than-temporary” and, if so, marks the investment to market through a charge to the Company’s statement of operations and comprehensive loss.

Restricted Cash

As of December 31, 2020, and 2019, the Company had $6.3 million and $0.1 million, respectively, of long-term restricted cash deposited with a financial institution. The entire amount is held in separate bank accounts to support letter of credit agreements related to the Company’s U.S. corporate offices.

Fair Value of Financial Instruments

Accounting Standards Codification (“ASC”) 820, Fair Value Measurement, establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company's own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances.

Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following:

Level 1—Observable inputs, such as quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Unobservable inputs which reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and inputs to the model.

To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement.

The carrying amounts of the Company’s financial instruments consisting of cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued liabilities and other current liabilities, approximate fair value due to their relatively short maturities.

Leases

The Company determines if an arrangement is, or contains, a lease at inception and then classifies the lease as operating or financing based on the underlying terms and conditions of the contract. Leases with terms greater than one year are initially recognized on the balance sheet as right-of-use assets and lease liabilities based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the incremental borrowing rate, which is the rate incurred to borrow, on a collateralized basis, an amount equal to the lease payments over a similar term and in a similar economic environment of the applicable country or region. Variable lease payments are excluded from the right of use assets and operating lease liabilities and are recognized in the period in which the obligation for those payments is incurred.

Property and Equipment, Net

Property and equipment are stated at cost less accumulated depreciation for acquired assets. Depreciation is computed using the straight-line method over the estimated useful lives of assets, which is generally four years for laboratory equipment, three years for computer equipment and office equipment, five years for computer software and five to seven years for furniture and fixtures. Leasehold improvements are stated at cost and amortized over the shorter of the useful life of the assets or the length of the lease. Upon sale or retirement of assets, the costs and related accumulated depreciation are removed from the consolidated balance sheet and the resulting gain or loss is reflected in operations. Maintenance and repairs are charged to operations as incurred.

Impairment of Long-Lived Assets

The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the assets. There have been no such impairments of long-lived assets in the years ended December 31, 2020 and 2019.

Research and Development Expenses

Costs related to research, design and development of products are charged to research and development expense as incurred. Research and development costs include, but are not limited to, payroll and personnel expenses, including stock-based compensation, laboratory supplies, outside services and allocated overhead, including rent, equipment, depreciation and utilities.

Accrued Research and Development

The Company has entered into various agreements with various third parties, including clinical investigator sites, contract research organizations (“CROs”) and contract manufacturing organizations (“CMOs”), to provide research and development activities. The Company’s accrued research and development costs are estimated based on the level of services performed, including the phase or completion of events, and contracted costs. Accrued clinical trial and related costs are estimated using data such as patient enrollment, clinical site activations or information provided by outside service providers regarding their actual costs incurred. Management determined accrual estimates through reports from and discussions with clinical personnel and outside service providers as to the progress of trials, or the services completed. The estimated costs of research and development provided, but not yet invoiced, are included in accrued and other current liabilities on the consolidated balance sheets. If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the performance of the related services are recorded as prepaid expenses or other assets until the services are rendered.

Stock-Based Compensation

The Company accounts for stock-based compensation in accordance with the provisions of ASC 718, Compensation-Stock Compensation. The Company measures stock-based compensation expense for stock options and restricted stock units granted to its employees, directors and non-employees based on the estimated fair value of the awards on the grant date. The fair value of options is calculated using the Black-Scholes valuation model, which requires the input of subjective assumptions, including (i) the expected stock price volatility, (ii) the calculation of expected term of the award, (iii) the risk-free interest rate, and (iv) expected dividends. The expense is recorded on a straight-line basis over the requisite service period, which is generally the vesting period, for the entire award. The Company accounts for forfeitures as they occur.

Prior to the adoption of Accounting Standards Update ("ASU") No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"), the measurement date for non-employee awards was generally the date the services are completed, resulting in financial reporting period adjustments to stock-based compensation during the vesting terms for changes in the fair value of the awards. After adoption of ASU 2018-07 as of January 1, 2019, the measurement date for non-employee awards is the date of grant without changes in the fair value of the award.

The Company has certain stock options and restricted stock units that vest in conjunction with certain performance conditions. At each reporting date, the Company is required to evaluate whether achievement of the performance conditions is probable. Compensation expense is recorded over the appropriate service period based upon the Company's assessment of accomplishing each performance provision.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires, among other things, that deferred income taxes be provided for temporary differences between the tax basis of the Company’s assets and liabilities and their financial statement reported amounts. In addition, deferred tax assets are recorded for the future benefit of utilizing net operating losses (“NOLs”) and research and development credit carryforwards and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. A valuation allowance is provided against deferred tax assets unless it is more likely than not that they will be realized.

The Company accounts for uncertain tax positions by assessing all material positions taken in any assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.

Comprehensive Loss

Comprehensive loss is composed of net loss and other comprehensive income (loss). Other comprehensive income (loss) consists primarily of unrealized gains and losses on debt securities.

Liability related to Sale of Future Royalties

On December 1, 2019, the Company and its subsidiary Kodiak Sciences GmbH entered into a funding agreement with Baker Bros. Advisors, LP (“BBA”), which holds more than 5% of the Company’s stock, pursuant to which BBA purchased the right to receive a capped 4.5% royalty on future net sales of KSI-301, the Company’s anti-VEGF antibody biopolymer conjugate therapy, in exchange for $225.0 million. Under the terms of the funding agreement, there is no obligation to repay any funding amount received, other than through the capped royalty payments on future product revenues. The Company recorded the funding amount paid by BBA as a liability on the consolidated balance sheet net of issuance costs, in accordance with ASC 730, Research and Development. Under ASC 730, the significant related party relationship between the Company and BBA creates an implicit obligation to repay the funding amount paid to the Company. Once royalty payments to BBA are determined to be probable and estimable, and if such amounts exceed the liability balance, the Company will impute interest to accrete the liability on a prospective basis based on such estimates. If and when the Company makes royalty payments under the funding agreement, it would reduce the liability balance at such time. Refer to Note 14.

Credit Losses – Available-for-Sale Debt Securities

For available-for-sale debt securities in an unrealized loss position, the Company will periodically assess its portfolio for impairment. The assessment first considers the intent or requirement to sell the security. If either of these criteria are met, the amortized cost basis will be written down to fair value through earnings.

If not met, the Company will evaluate whether the decline resulted from credit losses or other factors by considering the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security is compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses will be recorded, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income or loss, as applicable.

Net Loss per Share Attributable to Common Stockholders

Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of this calculation, the redeemable convertible preferred stock, preferred stock warrants, convertible notes, common stock subject to repurchase, and stock options are considered to be potentially dilutive securities. Basic and diluted net loss attributable to common stockholders per share is presented in conformity with the two-class method required for participating securities as the redeemable convertible preferred stock is considered a participating security. The Company’s participating securities do not have a contractual obligation to share in the Company’s losses. As such, the net loss is attributed entirely to common stockholders. Since the Company has reported net loss for all periods presented, diluted net loss per share is the same as basic net loss per common share for those periods.

Recent accounting pronouncements

From time to time, new accounting pronouncements are issued by the FASB, under its ASC or other standard setting bodies, and adopted by the Company as of the specified effective date, unless otherwise discussed below.

Recently Adopted Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). In July 2018, the FASB issued ASU 2018-10, Leases (Topic 842), Codification Improvements, and ASU 2018-11, Leases (Topic 842), Targeted Improvements. ASU 2018-10 clarified certain provisions and corrected unintended applications of the guidance such as the application of implicit rate, lessee reassessment of lease classification, and certain transition adjustments that should be recognized to earnings rather than to stockholders' equity. ASU 2018-11 provided an alternative transition method and practical expedient for separating contract components for the adoption of Topic 842. ASU 2016-02, ASU 2018-10, and ASU 2018-11 (collectively, "the new lease standards") superseded the previous leases standard, ASC 840 Leases.

The Company adopted ASC 842 effective January 1, 2019 using the modified retrospective approach to recognize a cumulative-effect adjustment on the effective date and to not adjust financial information and disclosures required under the new lease standards for comparative prior periods. The Company did not elect for the package of practical expedients and assessed all contracts at the transition date. The Company did not utilize the practical expedient which allows the use of hindsight in determining lease term and assessing impairment in right-of-use assets. The Company elected to apply the practical expedient and accounted for each lease component and related non-lease component as one single component. The Company elected the practical expedient not to recognize leases with terms of one year or less on the balance sheet.

The adoption of the new lease standards on January 1, 2019 resulted in the initial recognition of right-of-use asset of $2.2 million and operating lease liability of $2.3 million and derecognition of noncurrent deferred liabilities of $0.2 million related to the operating lease for the Company’s office and laboratory space in Palo Alto, California on the consolidated balance sheets with no material impact to the consolidated statements of operations, stockholders’ equity or cash flows. Refer to Note 7.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 362): Measurement of Credit Losses on Financial Statements and ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which intends to improve financial reporting by requiring earlier recognition of credit losses on certain financial assets, such as available-for-sale debt securities. The Company assessed the impact of ASU 2016-13 on its available-for-sale debt securities and determined there were no credit losses within the portfolio requiring an allowance upon adoption. The Company adopted this new guidance as of January 1, 2020, which did not impact its consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-13, Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements, which eliminates, adds and modifies certain disclosure requirements for fair value measurements as part of the FASB’s disclosure framework project. Among the changes, entities will no longer be required to disclose the amount of and reasons for transfers between Levels 1 and 2 of the fair value hierarchy but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The Company adopted this new guidance as of January 1, 2020, which did not impact its consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which clarifies the accounting for implementation, set-up, and other upfront costs incurred in cloud computing arrangements. The Company adopted this new guidance as of January 1, 2020, which did not impact its consolidated financial statements and related disclosures.

New Accounting Pronouncements Not Yet Adopted

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740. This guidance is effective for fiscal years beginning after December 15, 2020, including interim periods therein, and early adoption is permitted. The Company has early adopted ASU 2019-12 in 2020; the effect was not material on the Company’s financial statements.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Property and Equipment, net

3. Property and Equipment, net

Property and equipment, net consists of the following (in thousands):

	December 31, 2020			December 31, 2019

Leasehold improvement	$	1,285		$	1,265
Laboratory equipment		3,351			1,125
Furniture and fixtures		214			204
Computer hardware		31			—
Computer software		89			79
Office equipment		107			94
Construction in progress		2,229			—
Total property and equipment		7,306			2,767
Less: Accumulated depreciation		(2,170	)		(1,771	)
Property and equipment, net	$	5,136		$	996

All property and equipment are maintained in the United States and Switzerland. Depreciation expense, including depreciation of assets under capital leases, was $0.5 million, $0.5 million and $0.5 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Accrued Liabilities and Other Current Liabilities

12 Months Ended

Dec. 31, 2019

Accounts Payable And Accrued Liabilities Current [Abstract]

Accrued Liabilities and Other Current Liabilities

4. Accrued Liabilities and Other Current Liabilities

Accrued liabilities and other current liabilities consist of the following (in thousands):

	December 31, 2020		December 31, 2019
Accrued clinical trial and related costs	$	11,119	$	4,056
Accrued research and development		3,082		838
Accrued salaries and benefits		5,094		3,108
Accrued legal fees		252		302
Accrued professional fees		253		195
Accrued other liabilities		602		159
Total accrued and other current liabilities	$	20,402	$	8,658

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

5. Fair Value Measurements

The following tables present the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis (in thousands):

	Fair Value Measurements at December 31, 2020
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	917,485	$	—	$	—	$	917,485
Marketable securities:
U.S. treasury securities		—		10,006		—		10,006
Corporate notes		—		14,572		—		14,572
Total	$	917,485	$	24,578	$	—	$	942,063

	Fair Value Measurements at December 31, 2019
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	155,276	$	—	$	—	$	155,276
Repurchase agreement		50,000		—		—		50,000
Commercial paper		—		5,987		—		5,987
Marketable securities:
U.S. treasury securities		—		50,185		—		50,185
Commercial paper		—		34,533		—		34,533
Corporate notes		—		51,662		—		51,662
Total	$	205,276	$	142,367	$	—	$	347,643

As of December 31, 2020, the fair value of the liability related to sale of future royalties is based on our current estimates of future royalties expected to be paid to BBA, which are considered Level 3 inputs. Refer to Note 14. There were no liabilities measured at fair value on a recurring and non-recurring basis as of December 31, 2019. There were no transfers of assets or liabilities between the fair value measurement levels during the years ended December 31, 2020 and 2019.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Marketable Securities

12 Months Ended

Dec. 31, 2020

Investments Debt And Equity Securities [Abstract]

Marketable Securities

6. Marketable Securities

The marketable securities are classified as available-for-sale and consist of U.S. treasury securities, corporate notes and commercial paper. The fair value measurement data for marketable securities is obtained from independent pricing services. The Company validates the prices provided by the third-party pricing services by understanding the valuation methods and data sources used and analyzing the pricing data in certain instances.

The following table summarizes the marketable securities (in thousands):

	December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. treasury securities	$	10,003	$	3		—	$	10,006
Corporate notes		14,522		50		—		14,572
Total marketable securities, current	$	24,525	$	53	$	—	$	24,578

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. treasury securities	$	50,190	$	—	$	(5	)	$	50,185
Commercial paper		34,532		1		—			34,533
Corporate notes		39,956		13		(3	)		39,966
Total marketable securities, current	$	124,678	$	14	$	(8	)	$	124,684

Corporate notes	$	11,692	$	4	$	—		$	11,696
Total marketable securities, noncurrent	$	11,692	$	4	$	—		$	11,696

All marketable securities held at December 31, 2020 had effective maturities of less than one year. There were no realized gains or losses recognized on the sale or maturity of available-for-sale debt securities during the year ended December 31, 2020 and as a result, the Company did not reclassify any amounts out of accumulated comprehensive loss. No marketable securities with unrealized losses as of December 31, 2020. All marketable securities with unrealized losses as of December 31, 2019 have been in a loss position for less than twelve months and the loss is not material. These marketable securities were not considered to be other-than-temporarily impaired.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. Commitments and Contingencies

Leases

Palo Alto, California Leases

In June 2020, the Company entered into lease agreements for two buildings at 1200 and 1250 Page Mill Road in Palo Alto, California, which are now the Company’s U.S. corporate offices. The facilities are approximately 82,662 square feet and 72,812 square feet, respectively and include office and laboratory space. For 1200 Page Mill Road, the monthly rent during the initial 6.5-year term will be approximately $0.6 million, with annual year-over-year increases of 3% plus certain operating expenses and taxes and total rent abatement of approximately $7.2 million. The Company has an option to extend the lease term for a period of 6.5 years. For 1250 Page Mill Road, the monthly rent during the initial 13-year term will be approximately $0.5 million, with annual year-over-year increases of 3% plus certain operating expenses and taxes and total rent abatement of approximately $6.3 million. The Landlord will provide a tenant improvement allowance of approximately $1.2 million and $10.6 million for each building, respectively. The Company has two options to extend the lease term for a period of 5 years each. The Company determined that the renewal options were not reasonably certain at lease inception for the two buildings. The Company executed a $10.9 million cash-collateralized letter of credit, which was subsequently reduced to $6.2 million as a result of meeting certain reduction requirements specified therein. The cash collateralizing the letter of credit is classified as restricted cash on the Company’s consolidated balance sheets. Under ASC 842, the Company classified these leases as operating leases and recorded right-of-use assets and lease liabilities on the lease commencement date.

The Company continues to lease office and laboratory space at 2631 Hanover Street in Palo Alto, California. The Company entered into a lease agreement in January 2013 which was amended in March 2016 and extended the lease term until October 2023. The Company classified this lease as an operating lease and recorded a right-of-use asset and lease liability on January 1, 2019 and recognized rent expense on a straight-line basis throughout the remaining lease term.

Switzerland Lease

In April 2020, the Company entered into a lease agreement for office and laboratory space at Rottenstrasse 5 in Visp, Switzerland. The space is approximately 1,000 square meters. The initial lease term is 5 years, with automatic renewals every 5 years for a maximum lease term of 15 years. The monthly rent during the initial 5-year term will be approximately 32 thousand Swiss Francs plus certain operating expenses and taxes. Under ASC 842, the Company classified these leases as operating leases and recorded right-of-use assets and lease liabilities on the lease commencement date.

The maturities of the operating lease liabilities as of December 31, 2020 were as follows (in thousands):

Year ending December 31,	As of December 31, 2020
2021	$	4,288
2022		7,660
2023		14,598
2024		15,037
2025		15,475
Thereafter		71,462
Total undiscounted lease payments		128,520
Less: imputed interest		(51,118	)
Total operating lease liabilities	$	77,402

The minimum lease payments above do not include any related common area maintenance charges or real estate taxes. The weighted-average remaining lease terms and weighted-average discount rates were as follows:

December 31,

2020

December 31,

2019

Weighted-average remaining lease term (in years)

9.5

3.8

Weighted-average discount rate

6.7

8.5

Embedded lease

In August 2020, the Company and its subsidiary Kodiak Sciences GmbH entered into a manufacturing agreement with a contract manufacturing organization for the clinical and commercial supply of drug substance for KSI-301, the Company’s proprietary therapeutic candidate for the treatment and prevention of retinal vascular diseases. A custom-built manufacturing suite is planned to be completed and dedicated to the manufacture of the Company’s drug substance with an estimated capital contribution of 40 million Swiss Francs from the Company. Construction of the manufacturing suite is targeted for completion in 2021. The Company will be required to pay annual suite fees of 12 million Swiss Francs for 2021 and 16 million Swiss Francs for each year thereafter, which covers the manufacturing fees for a specified number of batches, and the Company may pay for additional batches to be manufactured. The manufacturing agreement has an initial term of eight years, and the Company has the right to extend the term up to a total of 16 years.

The Company concluded that this agreement contains an embedded lease as the custom-built manufacturing suite will be dedicated for the Company’s use. As of December 31, 2020, the Company did not have control of this manufacturing space and therefore, did not record a right-of-use asset and corresponding lease liability. These commitments are not included in the above table.

Manufacturing Agreement

The Company has entered into service agreements with Lonza AG and its affiliates (“Lonza”), pursuant to which Lonza agreed to perform activities in connection with the manufacturing process of certain compounds. Such agreements, and related amendments, state that planned activities that are included in the signed work orders are, in some cases, binding and, hence, obligate the Company to pay the full price of the work order upon satisfactory delivery of products and services or obligate the Company to the binding amount regardless of whether such planned activities are in fact performed. Per the terms of the agreements, the Company has the option to cancel signed orders at any time upon written notice, which may or may not be subject to payment of a cancellation fee. The level of cancellation fees may be dependent on the timing of the written notice in relation to the commencement date of the work, with the maximum cancellation amount dependent on the agreement or the work order. Under these agreements, the total amount of contractual obligations, over a period of ten years, are cancellable and subject to varying levels of cancellation fees, were $242.3 million and $4.7 million, including accrued amounts, as of December 31, 2020 and 2019, respectively. Purchases under this agreement for the years ended December 31, 2020, 2019 and 2018 were $16.8 million, $7.9 million and $2.8 million, respectively. As of December 31, 2020, the Company had not incurred any cancellation fees for the work performed by Lonza.

Other Funding Commitments

In the normal course of business, the Company enters into agreements with third-parties for services to be provided to the Company. Generally, these agreements provide for termination upon notice, with specified amounts due upon termination based on the timing of termination and the terms of the agreement. The actual amounts and timing of payments under these agreements are uncertain and contingent upon the initiation and completion of services to be provided to the Company. As of December 31, 2020 and 2019, the total amount of noncancellable purchase commitments, including potential cancellation fees were $0.5 million and $0.7 million, respectively.

The Company is also party to a cancellable assignment and license agreement that would require the Company to make milestone payments of up to $33.2 million and royalty payments on net sales of products utilizing KSI-201 and related technology. Such milestones and royalties are dependent on future activity or product sales and are not estimable.

The Company has also entered into various cancellable license agreements for certain technology. The Company may be obligated to make payments on future sales of specified products associated with such license agreements. Such payments are dependent on future product sales and are not estimable.

Tenant Improvement Allowance Payable

In May 2013, the Company entered into a tenant improvement allowance agreement with its landlord. The agreement allowed the Company to draw down $0.3 million for tenant improvements related to the office lease over the period from the execution of the agreement to October 2018. The interest rate is 8% per year over the lease period. This tenant improvement allowance was repaid in October 2018.

In March 2016, the Company entered into a lease amendment, under which the Company is allowed to draw down an additional allowance of $0.4 million for tenant improvements related to the office lease over the period from the execution of the agreement to October 2023. The interest rate is 8% per year over 10 years. Principal and interest are payable on the first day of every month.

As of December 31, 2020 and 2019, the current portion of the tenant improvement allowance payable in accrued and other current liabilities was less than $0.1 million and less than $0.1 million, respectively. As of December 31, 2020 and 2019, the non-current portion of the tenant improvement allowance payable in other liabilities was $0.3 million and $0.3 million, respectively.

Legal Proceedings

From time to time, the Company may become involved in legal proceedings arising from the ordinary course of its business. Management is currently not aware of any matters that could have a material adverse effect on the Company’s financial position, results of operations or cash flows. The Company records a legal liability when it believes that it is both probable that a liability may be imputed, and the amount of the liability can be reasonably estimated. Significant judgment by the Company is required to determine both probability and the estimated amount.

Indemnification

To the extent permitted under Delaware law, the Company has agreed to indemnify its directors and officers for certain events or occurrences while the director or officer is, or was serving, at the Company’s request in such capacity. The indemnification period covers all pertinent events and occurrences during the director’s or officer’s service. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is not specified in the agreements; however, the Company has director and officer insurance coverage that reduces its exposure and enables the Company to recover a portion of any future amounts paid. The Company believes the estimated fair value of these indemnification agreements in excess of applicable insurance coverage is minimal.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

The provision (benefit) for income taxes consists of the following (in thousands):

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Current:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		14		—		—
Total current	$	14	$	—	$	—

Deferred:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		—		—		—
Total deferred	$	—	$	—	$	—
Provision (Benefit) for income taxes	$	14	$	—	$	—

The components of loss before income taxes were as follows (in thousands):

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
United States	$	(17,273	)	$	2,633		$	(17,273	)
Foreign		(115,809	)		(49,998	)		(24,170	)
Total loss before income taxes	$	(133,082	)	$	(47,365	)	$	(41,443	)

The tax effects of temporary differences that give rise to significant components of the net deferred tax assets are as follows (in thousands):

	December 31, 2020			December 31, 2019			December 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$	28,451		$	18,523		$	11,044
Intangible assets		12,088			12,112			7,588
Research and development tax credits		10,527			4,037			1,559
Stock-based compensation		8,405			1,539			394
Accruals		1,367			885			700
Operating lease liability		22,276			577			-
Property and equipment		127			143			109
Total deferred tax assets		83,241			37,816			21,394
Valuation allowance		(62,005	)		(37,249	)		(21,394	)
Net deferred tax assets		21,236			567			—
Deferred tax liabilities:
Operating lease right-of-use asset		(21,234	)		(534	)		—
Capitalized legal fees		(2	)		(33	)		—
Total deferred tax liabilities		(21,236	)		(567	)		—
Total net deferred tax assets	$	—		$	—		$	—

The Company has recorded a full valuation allowance against its net deferred tax assets due to the uncertainty as to whether such assets will be realized. The net change in the total valuation allowance for the years ended December 31, 2020, 2019 and 2018 was an increase of approximately $24.8 million, $15.9 million and $8.2 million, respectively.

NOLs and tax credit carry-forwards are subject to review and possible adjustment by the Internal Revenue Service (“IRS”) and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50% as defined under Sections 382 and 383 in the Internal Revenue Code, which could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the Company’s value immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed a Section 382 study through December 31, 2020 which concluded no such ownership change had occurred through December 31, 2020.

As of December 31, 2020, the Company had $50.1 million of federal and $171.0 million of state net operating loss available to offset future taxable income. A portion of the federal net operating loss carryforwards begin to expire in 2035 and the state net operating loss carryforwards begin to expire in 2035, if not utilized. $32.0 million of the federal net operating loss are not subject to expiration.

As of December 31, 2020, the Company also had federal and state research and development credit carryforwards of $10.2 million and $4.9 million, respectively. The federal research and development credit carryforwards expire beginning 2035. The California tax credit can be carried forward indefinitely.

A reconciliation of the Company’s effective tax rate to the statutory U.S. federal rate is as follows:

	December 31, 2020			December 31, 2019			December 31, 2018
Federal statutory income tax rate		21.0	%		21.0	%		21.0	%
State taxes		4.3			11.0			5.6
Foreign tax rate differential		(7.9	)		(12.4	)		(3.8	)
Change in valuation allowance		(17.3	)		(30.5	)		(18.3	)
Stock-based compensation		6.7			7.7			(0.6	)
Research tax credit		3.8			3.3			1.3
Other		—			(0.1	)		(0.1	)
Sale of future royalties		(9.4	)		—			—
Section 162(m)		(1.2	)		—			—
Fair value adjustments		—			—			(2.4	)
Extinguishment of convertible note		—			—			(2.7	)
Provision for income taxes		0.0	%		0.0	%		0.0	%

The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. As of December 31, 2020, 2019 and 2018, none of the unrecognized tax benefits would affect income tax expense with consideration of the valuation allowance. The Company does not anticipate the uncertain tax positions will materially change in the next 12 months. It is the Company's policy to include penalties and interest expense related to income taxes as a component of other expense, net as necessary.

The beginning and ending unrecognized tax benefits amounts are as follows (in thousands):

	December 31, 2020		December 31, 2019		December 31, 2018
Unrecognized tax benefits at beginning of period	$	1,838	$	398	$	357
Increases related to prior year tax positions		—		—		-
Increases related to current year tax positions		2,812		1,440		41
Unrecognized tax benefits at end of period	$	4,650	$	1,838	$	398

The Company files income tax returns in the United States and Switzerland. The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. All tax returns remain open for examination by the federal and state authorities for three and four years, respectively, from the date of utilization of any net operating loss or credits.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Preferred Stock

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Preferred Stock

9. Preferred Stock

As of December 31, 2020 and 2019, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue up to 10,000,000 shares of preferred stock at the par value of $0.0001 per share. As of December 31, 2020, there are no holders of the Company’s preferred stock.

Common Stock

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Common Stock

10. Common Stock

As of December 31, 2020 and 2019, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 490,000,000 shares of common stock at the par value of $0.0001 per share. Each share of common stock is entitled to one vote. The board of directors may declare and pay dividends to holders of common stock. The Company has never declared or paid any dividends on common stock.

The Company had reserved common stock for future issuances as follows:

	December 31, 2020		December 31, 2019
Exercise of options outstanding and release of restricted shares		7,257,221		6,830,442
Exercise of common stock warrants outstanding		399,999		399,999
Issuance of common stock under the 2018 Equity Incentive Plan		2,742,183		2,118,877
Issuance of common stock under the 2018 Employee Share Purchase Plan		460,000		460,000
Total		10,859,403		9,809,318

Stock-Based Compensation

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

11. Stock-Based Compensation

2018 Equity Incentive Plan

In August 2018, the Company adopted the 2018 Equity Incentive Plan (“2018 Plan”), which became effective on the business day prior to the effectiveness of the registration statement relating to the IPO. The 2018 Plan initially reserved 4,300,000 shares of common stock for the issuance of incentive stock options ("ISOs"), nonstatutory stock options, restricted stock, restricted stock units (“RSUs”), stock appreciation rights, performance units and performance shares to employees, directors and consultants of the Company. The number of shares available for issuance will increase annually on the first day of each fiscal year beginning in 2019 equal to the least of (1) 4,300,000 shares, and (2) 4% of outstanding shares of common stock as of the last day of the immediately preceding year, and (3) such other amount as determined by the board of directors. The exercise price of options must be equal to at least the fair market value of the common stock on the grant date. For ISOs, the term may not exceed ten years, except in respect to any participant with more than 10% of voting power of all classes or stock, then the term may not exceed five years and the exercise price must be equal to at least 110% of the fair market value of the common stock on the grant date. Options granted generally vest over four years.

The number of shares available for issuance increased by 1,776,761 shares in 2020 and there were 2,742,183 shares available for grant under the 2018 Plan as of December 31, 2020.

Shares Subject to Repurchase

The Company has a right of repurchase with respect to unvested shares issued upon early exercise of options at an amount equal to the lower of (1) the exercise price of each restricted share being repurchased and (2) the fair market value of such restricted share at the time the Company’s right of repurchase is exercised. The Company’s right to repurchase these shares lapses as those shares vest over the requisite service period.

Shares purchased by employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules. Cash received for early exercised stock options is recorded as accrued liabilities and other current liabilities on the consolidated balance sheet and is reclassified to common stock and additional paid-in capital as such shares vest. At December 31, 2020 and 2019, there are no early exercised stock options that remained subject to the Company’s right of repurchase.

Stock Options

Stock option activity under the 2018 Plan and 2015 Plan is summarized as follows:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2019		6,671,542		$	17.90		8.73	$	362,081
Granted		1,068,335		$	55.27
Exercised		(704,675	)	$	8.89
Forfeited or canceled		(137,926	)	$	25.07
Outstanding at December 31, 2020		6,897,276		$	24.52		8.07	$	841,704
Shares exercisable December 31, 2020		3,769,990
Vested and expected to vest December 31, 2020		6,897,276

The weighted-average grant date fair value of the stock options granted for 2020, 2019 and 2018 was $32.44, $34.11 and $4.36 per share, respectively. The aggregate intrinsic value represents the value of the Company’s closing stock price on the last trading day of the period in excess of the weighted-average exercise price multiplied by the number of options outstanding or exercisable.

Employee Stock Options

Prior to the Company’s IPO, the fair value of the shares of common stock underlying the stock options was determined by the board of directors with assistance from management and external appraisers as there has been no historical public market for the Company’s common stock. Subsequent to the Company’s IPO, the fair value of the Company’s common stock is determined based on its closing market price.

The Company estimated the fair value of employee stock options using the Black-Scholes valuation model. The fair value of employee stock options was estimated using the following weighted-average assumptions:

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
Expected volatility		66	%		68	%		59	%
Risk-free interest rate		0.39	%		1.65	%		2.82	%
Dividend yield		0	%		0	%		0	%
Expected term		6.00			5.78			6.06

Expected Term. The expected term is calculated using the simplified method, which is available where there is insufficient historical data about exercise patterns and post-vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant, or for each vesting-tranche for awards with graded vesting. The mid-point between the vesting date and the maximum contractual expiration date is used as the expected term under this method. For awards with multiple vesting-tranches, the times from grant until the mid-points for each of the tranches may be averaged to provide an overall expected term.

Expected Volatility. As the Company does not have sufficient trading history for its common stock, our approach to estimating expected volatility is to phase in our own common stock trading history and supplement the remaining historical information with an average historical stock price volatility of a peer group of publicly traded companies to be representative of its expected future stock price volatility. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size and financial leverage of potential comparable companies. For each grant, the Company measured historical volatility over a period equivalent to the expected term. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Risk-Free Interest Rate. The risk-free interest rate is based on the implied yield currently available on U.S. Treasury zero-coupon issues with a remaining term equivalent to the expected term of a stock award.

Expected Dividend Rate. The Company has not paid and does not anticipate paying any dividends in the near future. Accordingly, the Company has estimated the dividend yield to be zero.

The total fair value of employee options vested during the years ended December 31, 2020, 2019 and 2018 was $19.7 million, $4.6 million and $1.2 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2020, 2019 and 2018 for options granted to employees was $20.8 million, $5.7 million and $2.0 million, respectively.

Non-Employee Stock Options

The Company granted 41,500, 15,000 and 215,000 stock options to non-employees during the years ended December 31, 2020, 2019 and 2018, respectively.

Subsequent to the adoption of ASU 2018-07 effective January 1, 2019, existing stock options granted to non-employees will no longer be revalued, and the estimated fair value of new stock options granted to non-employees will be calculated on the date of grant and not remeasured, similar to stock options granted to employees. The fair value of non-employee stock options was estimated using the following weighted-average assumptions:

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
Expected volatility		67	%		73	%		68	%
Risk-free interest rate		0.36	%		1.61	%		2.71	%
Dividend yield		0	%		0	%		0	%
Expected term		5.56			6.08			9.30

Stock-based compensation expense recognized during the years ended December 31, 2020, 2019 and 2018 for options granted to non-employees was $0.7 million, $0.1 million and $0.4 million, respectively.

Restricted Shares

Restricted share activity, including restricted stock awards (“RSAs”), restricted stock units (“RSUs”), and performance-based restricted stock units (“PSUs”), under the 2018 Plan and 2015 Plan is summarized as follows:

	Number of Restricted Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2019		160,747		$	60.81
Granted		236,045		$	52.18
Vested		(23,848	)	$	9.21
Shares withheld related to net share settlement of RSUs		(7,999	)	$	9.90
Canceled		(5,000	)	$	72.46
Unvested at December 31, 2020		359,945		$	59.54

Restricted Stock Awards

Under the terms of the restricted stock agreements, the awards vest over four years, which is the requisite service period. Recipients of restricted stock awards generally have voting and dividend rights with respect to such shares upon grant without regard to vesting. Shares of restricted stock that do not vest are subject to forfeiture. The Company recognizes stock-based compensation expense for RSAs on a straight-line basis over the requisite service period for the entire award.

The Company did not grant any RSA to employees in 2020. The total fair value of RSAs vested during the years ended December 31, 2020, 2019 and 2018 was $nil million, less than $0.1 million and $0.2 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2020, 2019 and 2018 for RSAs was $nil million, less than $0.1 million and $0.2 million, respectively.

Restricted Stock Units

RSUs will vest in four equal annual installments over four years, which is the requisite service period after that date.

The Company granted 236,045 RSUs to employees in 2020. The total fair value of RSUs vested during the year ended December 31, 2020 and 2019 was $0.3 million and $0.3 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2020, 2019 and 2018 for RSUs was $1.9 million, $0.3 million, and less than $0.1 million, respectively.

Performance-Based Stock Options and Restricted Stock Units

These performance-based equity awards will vest one-quarter upon the achievement of specific clinical development milestones. The remaining shares will then vest in three equal annual installments after that date. Performance-based stock options are recorded as expense beginning when vesting events are determined to be probable.

The Company did not grant performance-based equity awards to employees in 2020. None of these performance-based equity awards vested during 2020 or 2019. The Company believes that the achievement of the requisite performance condition continues to be probable. Stock-based compensation expense recognized during the years ended December 31, 2020, 2019 and 2018 for the performance-based equity awards was $7.2 million, less than $0.1 million and $nil million, respectively.

The fair value of performance-based stock options was estimated using the following weighted-average assumptions:

The weighted-average grant date fair value was $47.89 per share for performance-based stock options and $73.51 per share for performance-based restricted stock units.

2018 Employee Share Purchase Plan

In August 2018, the Company adopted the 2018 Employee Share Purchase Plan (“ESPP”), which became effective on the business day prior to the effectiveness of the registration statement relating to the IPO. A total of 460,000 shares of common stock were initially reserved for issuance under the ESPP. The initial offering period of the ESPP was authorized by the Company’s board of directors and commenced on January 4, 2021.

Stock-Based Compensation Expense

Stock-based compensation is classified in the consolidated statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Research and development	$	16,957	$	3,496	$	1,535
General and administrative		13,711		2,614		1,073
Total stock-based compensation	$	30,668	$	6,110	$	2,608

As of December 31, 2020, the Company had $91.4 million of unrecognized compensation expense related to unvested stock options and unvested restricted stock awards and units that is expected to be recognized over a weighted-average period of 2.9 years.

Net Loss per Share Attributable to Common Stockholders

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss per Share Attributable to Common Stockholders

12. Net Loss per Share Attributable to Common Stockholders

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders which excludes shares which are legally outstanding, but subject to repurchase by the Company (in thousands, except share and per share data):

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
Numerator:
Net loss attributable to common stockholders	$	(133,096	)	$	(47,365	)	$	(41,443	)
Denominator:
Weighted-average shares outstanding		45,741,845			37,869,291			15,136,197
Less: weighted-average unvested restricted shares and shares subject to repurchase		—			(15,675	)		(159,682	)
Weighted-average shares outstanding used in computing net loss per share attributable to common stockholders, basic and diluted		45,741,845			37,853,616			14,976,515
Net loss per share attributable to common stockholders, basic and diluted	$	(2.91	)	$	(1.25	)	$	(2.77	)

The following potentially dilutive securities, presented on an as-converted to common stock basis, were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive:

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Exercise of options outstanding		6,897,276		6,671,542		5,135,267
Unvested restricted shares		359,945		160,747		50,450
Total		7,257,221		6,832,289		5,185,717

401(k) Plan

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

401(k) plan

13. 401(k) Plan

In 2011, the Company adopted a 401(k) retirement and savings plan covering all employees. The 401(k) plan allows employees to make pre- and post-tax contributions up to the maximum allowable amount set by the Internal Revenue Service. The 401(k) plan was amended to include an employer matching provision in 2019. The Company will make matching contributions of 100% of employee contributions up to a maximum of 50% of the individual maximum contribution limit allowed under the IRS rules. For the year ended December 31, 2020 and 2019, the expense related to the matching contributions was $0.6 million and $0.3 million, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Liability Related to Sale of Future Royalties

12 Months Ended

Dec. 31, 2020

14. Liability related to Sale of Future Royalties

On December 1, 2019, the Company and its subsidiary Kodiak Sciences GmbH entered into a funding agreement with BBA, which holds more than 5% of the Company’s stock, pursuant to which BBA purchased the right to receive a capped 4.5% royalty on future net sales of KSI-301, the Company’s anti-VEGF antibody biopolymer conjugate therapy, in exchange for $225.0 million. The royalty terminates upon the date that BBA has received an aggregate amount equal to 4.5 times the funding amount paid to the Company, unless earlier terminated or repurchased by the Company. Under the terms of the funding agreement, there is no obligation to repay any funding amount received, other than through the capped royalty payments on future product revenues. The Company has the option, exercisable at any point during the term of the funding agreement, to repurchase 100% of the royalties due to BBA for a purchase price equal to 4.5 times the funding amount paid to the Company as of such time, less amounts paid by the Company to BBA.

The closing of the funding agreement was subject to certain conditions and occurred in February 2020. The Company received $100.0 million of the funding on February 4, 2020. The remaining $125.0 million, subject to delivery of notice by the Company, payable upon enrollment of 50% of the patients in the RVO clinical program.

The Company recorded the initial $100.0 million payment as a liability on the consolidated balance sheet net of issuance costs. Once royalty payments to BBA are determined to be probable and estimable, and if such amounts exceed the liability balance, the Company will impute interest to accrete the liability on a prospective basis based on such estimates. If and when the Company makes royalty payments under the funding agreement, it would reduce the liability balance at such time. As of December 31, 2020, royalty payments are not probable and estimable.

For the year ended December 31, 2020, no interest expense was recognized for the liability related to the sale of future royalties.

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

15. Selected Quarterly Financial Data (unaudited)

The following table provides the selected quarterly financial information for the years, 2020 and 2019 (in thousands, except per share data):

	Three Months Ended
	March 31, 2020			June 30, 2020			September 30, 2020			December 31, 2020
Loss from operations	$	(25,723	)	$	(26,779	)	$	(36,663	)	$	(46,842	)
Net loss	$	(24,392	)	$	(25,999	)	$	(36,122	)	$	(46,583	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.54	)	$	(0.58	)	$	(0.80	)	$	(0.97	)

	Three Months Ended
	March 31, 2019			June 30, 2019			September 30, 2019			December 31, 2019
Loss from operations	$	(8,460	)	$	(11,814	)	$	(12,732	)	$	(16,184	)
Net loss	$	(7,984	)	$	(11,385	)	$	(12,380	)	$	(15,616	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.21	)	$	(0.31	)	$	(0.33	)	$	(0.40	)

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”).
Reclassification	Reclassification Certain prior period amounts in the consolidated financial statements have been reclassified to conform to the current period presentation.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the Company’s accounts and the accounts of Kodiak Sciences Financing Corporation and Kodiak Sciences China, the Company’s direct wholly owned subsidiaries, incorporated in the United States and Cayman Islands, respectively, and Kodiak Sciences GmbH and Kodiak Sciences Valais GmbH, the Company’s indirect wholly owned subsidiaries, both incorporated in Switzerland. All intercompany accounts and transactions have been eliminated. The functional and reporting currency of the Company and its subsidiaries is the U.S. dollar. The aggregate foreign currency transaction loss included in determining net loss was $0.3 million, less than $0.1 million and $0.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.
Segments	Segments The Company operates and manages its business as one reportable and operating segment, which is the business of research and development of drugs for ophthalmic diseases. The chief operating decision maker reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and expenses during the reporting period. The impact of the ongoing COVID-19 pandemic continues to evolve. As a result, certain estimates and assumptions required increased judgment and carried a higher degree of variability and volatility, including but not limited to, the fair value of marketable securities, performance-based equity awards, and research and development accruals. As events continue to unfold and additional information becomes available, these estimates may change materially in future periods. Actual results could differ from those estimates.
Risk and Uncertainties	Risk and Uncertainties In March 2020, the World Health Organization declared a pandemic due to the global COVID-19 outbreak. The significant uncertainties caused by the ongoing COVID-19 pandemic may negatively impact the Company’s operations, liquidity, and capital resources and will depend on certain evolving developments, including the duration and spread of the outbreak, regulatory and private sector responses and the impact on employees and vendors including supply chain and clinical partners, all of which are uncertain and cannot be predicted. During this pandemic, the Company continues to work closely with clinical sites towards maximal patient safety and the lowest number of missed visits and study discontinuations. The Company has taken and continues to take proactive measures to maintain the integrity of its ongoing clinical studies. Despite these efforts, the ongoing COVID-19 pandemic could significantly impact clinical trial enrollment and completion of its clinical studies. The Company will continue to monitor the COVID-19 situation and its impact on the ability to continue the development of, and seek regulatory approvals for, the Company’s product candidates, and begin to commercialize any approved products. The Company’s future results of operations involve a number of risks and uncertainties common to clinical-stage companies in the biotechnology industry. The Company’s product candidates are in development and the Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biotechnology companies. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential drug candidates, uncertainty of market acceptance of any of the Company’s product candidates that receive regulatory approval, competition from new technological innovations, substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals, contract manufacturer and research organizations, and other suppliers. Products developed by the Company require approvals from the U.S. Food and Drug Administration (“FDA”) or other international regulatory agencies prior to commercial sales. There can be no assurance that any of the Company’s product candidates will receive the necessary approvals. If the Company is denied approval, approval is delayed or the Company is unable to maintain approvals, it could have a materially adverse impact on the Company. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company expects to incur substantial operating losses for the next several years and will need to obtain additional financing in order to complete clinical trials and launch and commercialize any product candidates for which it receives regulatory approval. There can be no assurance that such financing will be available or will be on terms acceptable by the Company.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and marketable securities. As of December 31, 2020 and 2019, cash, cash equivalents and marketable securities were invested primarily in money market funds, overnight repurchase agreements, U.S. treasury securities, commercial paper and corporate notes through highly rated financial institutions. Investments are restricted, in accordance with the Company’s investment policy, to a concentration limit per issuer or sector.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with stated maturities of three months or less at the date of purchase to be cash equivalents.
Marketable Securities	Marketable Securities The Company invests excess cash balances in marketable securities. The investments in marketable securities are classified as either held-to-maturity or available-for-sale based on facts and circumstances present at the time of purchase. Marketable securities with a remaining maturity date greater than one year are classified as non-current. The Company’s marketable securities consist of U.S. treasury securities, commercial paper, and corporate bonds. Marketable securities are carried at fair value with the unrealized gains and losses included in other comprehensive income (loss) as a component of stockholders’ equity until realized. Any premium or discount arising at purchase of marketable debt securities is amortized and/or accreted to other income (expense), net over the life of the instrument. Realized gains and losses are determined using the specific identification method and are included in other income (expense), net. If any adjustment to fair value reflects a decline in value of the investment, the Company considers all available evidence to evaluate the extent to which the decline is “other-than-temporary” and, if so, marks the investment to market through a charge to the Company’s statement of operations and comprehensive loss.
Restricted Cash	Restricted Cash As of December 31, 2020, and 2019, the Company had $6.3 million and $0.1 million, respectively, of long-term restricted cash deposited with a financial institution. The entire amount is held in separate bank accounts to support letter of credit agreements related to the Company’s U.S. corporate offices.
Fair Value Measurements	Fair Value of Financial Instruments Accounting Standards Codification (“ASC”) 820, Fair Value Measurement, establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company's own assumptions (unobservable inputs). Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company's assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following: Level 1—Observable inputs, such as quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs which reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and inputs to the model. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument's level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts of the Company’s financial instruments consisting of cash and cash equivalents, prepaid expenses and other current assets, accounts payable and accrued liabilities and other current liabilities, approximate fair value due to their relatively short maturities.
Leases	Leases The Company determines if an arrangement is, or contains, a lease at inception and then classifies the lease as operating or financing based on the underlying terms and conditions of the contract. Leases with terms greater than one year are initially recognized on the balance sheet as right-of-use assets and lease liabilities based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes the incremental borrowing rate, which is the rate incurred to borrow, on a collateralized basis, an amount equal to the lease payments over a similar term and in a similar economic environment of the applicable country or region. Variable lease payments are excluded from the right of use assets and operating lease liabilities and are recognized in the period in which the obligation for those payments is incurred.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation for acquired assets. Depreciation is computed using the straight-line method over the estimated useful lives of assets, which is generally four years for laboratory equipment, three years for computer equipment and office equipment, five years for computer software and five to seven years for furniture and fixtures. Leasehold improvements are stated at cost and amortized over the shorter of the useful life of the assets or the length of the lease. Upon sale or retirement of assets, the costs and related accumulated depreciation are removed from the consolidated balance sheet and the resulting gain or loss is reflected in operations. Maintenance and repairs are charged to operations as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the assets. There have been no such impairments of long-lived assets in the years ended December 31, 2020 and 2019.
Research and Development Expenses	Research and Development Expenses Costs related to research, design and development of products are charged to research and development expense as incurred. Research and development costs include, but are not limited to, payroll and personnel expenses, including stock-based compensation, laboratory supplies, outside services and allocated overhead, including rent, equipment, depreciation and utilities.
Accrued Research And Development	Accrued Research and Development The Company has entered into various agreements with various third parties, including clinical investigator sites, contract research organizations (“CROs”) and contract manufacturing organizations (“CMOs”), to provide research and development activities. The Company’s accrued research and development costs are estimated based on the level of services performed, including the phase or completion of events, and contracted costs. Accrued clinical trial and related costs are estimated using data such as patient enrollment, clinical site activations or information provided by outside service providers regarding their actual costs incurred. Management determined accrual estimates through reports from and discussions with clinical personnel and outside service providers as to the progress of trials, or the services completed. The estimated costs of research and development provided, but not yet invoiced, are included in accrued and other current liabilities on the consolidated balance sheets. If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the performance of the related services are recorded as prepaid expenses or other assets until the services are rendered.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation in accordance with the provisions of ASC 718, Compensation-Stock Compensation. The Company measures stock-based compensation expense for stock options and restricted stock units granted to its employees, directors and non-employees based on the estimated fair value of the awards on the grant date. The fair value of options is calculated using the Black-Scholes valuation model, which requires the input of subjective assumptions, including (i) the expected stock price volatility, (ii) the calculation of expected term of the award, (iii) the risk-free interest rate, and (iv) expected dividends. The expense is recorded on a straight-line basis over the requisite service period, which is generally the vesting period, for the entire award. The Company accounts for forfeitures as they occur. Prior to the adoption of Accounting Standards Update ("ASU") No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting ("ASU 2018-07"), the measurement date for non-employee awards was generally the date the services are completed, resulting in financial reporting period adjustments to stock-based compensation during the vesting terms for changes in the fair value of the awards. After adoption of ASU 2018-07 as of January 1, 2019, the measurement date for non-employee awards is the date of grant without changes in the fair value of the award. The Company has certain stock options and restricted stock units that vest in conjunction with certain performance conditions. At each reporting date, the Company is required to evaluate whether achievement of the performance conditions is probable. Compensation expense is recorded over the appropriate service period based upon the Company's assessment of accomplishing each performance provision.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires, among other things, that deferred income taxes be provided for temporary differences between the tax basis of the Company’s assets and liabilities and their financial statement reported amounts. In addition, deferred tax assets are recorded for the future benefit of utilizing net operating losses (“NOLs”) and research and development credit carryforwards and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. A valuation allowance is provided against deferred tax assets unless it is more likely than not that they will be realized. The Company accounts for uncertain tax positions by assessing all material positions taken in any assessment or challenge by relevant taxing authorities. Assessing an uncertain tax position begins with the initial determination of the position’s sustainability and is measured at the largest amount of benefit that is greater than fifty percent likely of being realized upon ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is composed of net loss and other comprehensive income (loss). Other comprehensive income (loss) consists primarily of unrealized gains and losses on debt securities.
Liability related to Sale of Future Royalties	Liability related to Sale of Future Royalties On December 1, 2019, the Company and its subsidiary Kodiak Sciences GmbH entered into a funding agreement with Baker Bros. Advisors, LP (“BBA”), which holds more than 5% of the Company’s stock, pursuant to which BBA purchased the right to receive a capped 4.5% royalty on future net sales of KSI-301, the Company’s anti-VEGF antibody biopolymer conjugate therapy, in exchange for $225.0 million. Under the terms of the funding agreement, there is no obligation to repay any funding amount received, other than through the capped royalty payments on future product revenues. The Company recorded the funding amount paid by BBA as a liability on the consolidated balance sheet net of issuance costs, in accordance with ASC 730, Research and Development. Under ASC 730, the significant related party relationship between the Company and BBA creates an implicit obligation to repay the funding amount paid to the Company. Once royalty payments to BBA are determined to be probable and estimable, and if such amounts exceed the liability balance, the Company will impute interest to accrete the liability on a prospective basis based on such estimates. If and when the Company makes royalty payments under the funding agreement, it would reduce the liability balance at such time. Refer to Note 14.
Credit Losses – Available-for-Sale Debt Securities	Credit Losses – Available-for-Sale Debt Securities For available-for-sale debt securities in an unrealized loss position, the Company will periodically assess its portfolio for impairment. The assessment first considers the intent or requirement to sell the security. If either of these criteria are met, the amortized cost basis will be written down to fair value through earnings. If not met, the Company will evaluate whether the decline resulted from credit losses or other factors by considering the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security is compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses will be recorded, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income or loss, as applicable.
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of this calculation, the redeemable convertible preferred stock, preferred stock warrants, convertible notes, common stock subject to repurchase, and stock options are considered to be potentially dilutive securities. Basic and diluted net loss attributable to common stockholders per share is presented in conformity with the two-class method required for participating securities as the redeemable convertible preferred stock is considered a participating security. The Company’s participating securities do not have a contractual obligation to share in the Company’s losses. As such, the net loss is attributed entirely to common stockholders. Since the Company has reported net loss for all periods presented, diluted net loss per share is the same as basic net loss per common share for those periods.
Recent Accounting Pronouncements	Recent accounting pronouncements From time to time, new accounting pronouncements are issued by the FASB, under its ASC or other standard setting bodies, and adopted by the Company as of the specified effective date, unless otherwise discussed below. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). In July 2018, the FASB issued ASU 2018-10, Leases (Topic 842), Codification Improvements, and ASU 2018-11, Leases (Topic 842), Targeted Improvements. ASU 2018-10 clarified certain provisions and corrected unintended applications of the guidance such as the application of implicit rate, lessee reassessment of lease classification, and certain transition adjustments that should be recognized to earnings rather than to stockholders' equity. ASU 2018-11 provided an alternative transition method and practical expedient for separating contract components for the adoption of Topic 842. ASU 2016-02, ASU 2018-10, and ASU 2018-11 (collectively, "the new lease standards") superseded the previous leases standard, ASC 840 Leases. The Company adopted ASC 842 effective January 1, 2019 using the modified retrospective approach to recognize a cumulative-effect adjustment on the effective date and to not adjust financial information and disclosures required under the new lease standards for comparative prior periods. The Company did not elect for the package of practical expedients and assessed all contracts at the transition date. The Company did not utilize the practical expedient which allows the use of hindsight in determining lease term and assessing impairment in right-of-use assets. The Company elected to apply the practical expedient and accounted for each lease component and related non-lease component as one single component. The Company elected the practical expedient not to recognize leases with terms of one year or less on the balance sheet. The adoption of the new lease standards on January 1, 2019 resulted in the initial recognition of right-of-use asset of $2.2 million and operating lease liability of $2.3 million and derecognition of noncurrent deferred liabilities of $0.2 million related to the operating lease for the Company’s office and laboratory space in Palo Alto, California on the consolidated balance sheets with no material impact to the consolidated statements of operations, stockholders’ equity or cash flows. Refer to Note 7. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 362): Measurement of Credit Losses on Financial Statements and ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which intends to improve financial reporting by requiring earlier recognition of credit losses on certain financial assets, such as available-for-sale debt securities. The Company assessed the impact of ASU 2016-13 on its available-for-sale debt securities and determined there were no credit losses within the portfolio requiring an allowance upon adoption. The Company adopted this new guidance as of January 1, 2020, which did not impact its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurements, which eliminates, adds and modifies certain disclosure requirements for fair value measurements as part of the FASB’s disclosure framework project. Among the changes, entities will no longer be required to disclose the amount of and reasons for transfers between Levels 1 and 2 of the fair value hierarchy but will be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The Company adopted this new guidance as of January 1, 2020, which did not impact its consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which clarifies the accounting for implementation, set-up, and other upfront costs incurred in cloud computing arrangements. The Company adopted this new guidance as of January 1, 2020, which did not impact its consolidated financial statements and related disclosures. New Accounting Pronouncements Not Yet Adopted In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ("ASU 2019-12"), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740. This guidance is effective for fiscal years beginning after December 15, 2020, including interim periods therein, and early adoption is permitted. The Company has early adopted ASU 2019-12 in 2020; the effect was not material on the Company’s financial statements.

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2020

Property Plant And Equipment [Abstract]

Summary of Property and Equipment, net

Property and equipment, net consists of the following (in thousands):

	December 31, 2020			December 31, 2019

Leasehold improvement	$	1,285		$	1,265
Laboratory equipment		3,351			1,125
Furniture and fixtures		214			204
Computer hardware		31			—
Computer software		89			79
Office equipment		107			94
Construction in progress		2,229			—
Total property and equipment		7,306			2,767
Less: Accumulated depreciation		(2,170	)		(1,771	)
Property and equipment, net	$	5,136		$	996

Accrued Liabilities and Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Accounts Payable And Accrued Liabilities Current [Abstract]

Schedule of Accrued Liabilities and Other Current Liabilities

Accrued liabilities and other current liabilities consist of the following (in thousands):

	December 31, 2020		December 31, 2019
Accrued clinical trial and related costs	$	11,119	$	4,056
Accrued research and development		3,082		838
Accrued salaries and benefits		5,094		3,108
Accrued legal fees		252		302
Accrued professional fees		253		195
Accrued other liabilities		602		159
Total accrued and other current liabilities	$	20,402	$	8,658

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Summary of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis

The following tables present the Company’s fair value hierarchy for assets and liabilities measured at fair value on a recurring basis (in thousands):

	Fair Value Measurements at December 31, 2020
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	917,485	$	—	$	—	$	917,485
Marketable securities:
U.S. treasury securities		—		10,006		—		10,006
Corporate notes		—		14,572		—		14,572
Total	$	917,485	$	24,578	$	—	$	942,063

	Fair Value Measurements at December 31, 2019
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	155,276	$	—	$	—	$	155,276
Repurchase agreement		50,000		—		—		50,000
Commercial paper		—		5,987		—		5,987
Marketable securities:
U.S. treasury securities		—		50,185		—		50,185
Commercial paper		—		34,533		—		34,533
Corporate notes		—		51,662		—		51,662
Total	$	205,276	$	142,367	$	—	$	347,643

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2020

Investments Debt And Equity Securities [Abstract]

Summary of Marketable Securities Held

The following table summarizes the marketable securities (in thousands):

	December 31, 2020
	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
U.S. treasury securities	$	10,003	$	3		—	$	10,006
Corporate notes		14,522		50		—		14,572
Total marketable securities, current	$	24,525	$	53	$	—	$	24,578

	December 31, 2019
	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. treasury securities	$	50,190	$	—	$	(5	)	$	50,185
Commercial paper		34,532		1		—			34,533
Corporate notes		39,956		13		(3	)		39,966
Total marketable securities, current	$	124,678	$	14	$	(8	)	$	124,684

Corporate notes	$	11,692	$	4	$	—		$	11,696
Total marketable securities, noncurrent	$	11,692	$	4	$	—		$	11,696

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Summary of Maturities of Operating Lease Liabilities

The maturities of the operating lease liabilities as of December 31, 2020 were as follows (in thousands):

Year ending December 31,	As of December 31, 2020
2021	$	4,288
2022		7,660
2023		14,598
2024		15,037
2025		15,475
Thereafter		71,462
Total undiscounted lease payments		128,520
Less: imputed interest		(51,118	)
Total operating lease liabilities	$	77,402

Summary of Lessee, Weighted Average Remaining Lease Term and Weighted Average Discount Rates

The weighted-average remaining lease terms and weighted-average discount rates were as follows:

December 31,

2020

December 31,

2019

Weighted-average remaining lease term (in years)

9.5

3.8

Weighted-average discount rate

6.7

8.5

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Provision (Benefit) for Income Taxes

The provision (benefit) for income taxes consists of the following (in thousands):

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Current:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		14		—		—
Total current	$	14	$	—	$	—

Deferred:
Federal	$	—	$	—	$	—
State		—		—		—
Foreign		—		—		—
Total deferred	$	—	$	—	$	—
Provision (Benefit) for income taxes	$	14	$	—	$	—

Components of Loss before Income Taxes

The components of loss before income taxes were as follows (in thousands):

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
United States	$	(17,273	)	$	2,633		$	(17,273	)
Foreign		(115,809	)		(49,998	)		(24,170	)
Total loss before income taxes	$	(133,082	)	$	(47,365	)	$	(41,443	)

Components of Deferred Tax Assets

The tax effects of temporary differences that give rise to significant components of the net deferred tax assets are as follows (in thousands):

	December 31, 2020			December 31, 2019			December 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$	28,451		$	18,523		$	11,044
Intangible assets		12,088			12,112			7,588
Research and development tax credits		10,527			4,037			1,559
Stock-based compensation		8,405			1,539			394
Accruals		1,367			885			700
Operating lease liability		22,276			577			-
Property and equipment		127			143			109
Total deferred tax assets		83,241			37,816			21,394
Valuation allowance		(62,005	)		(37,249	)		(21,394	)
Net deferred tax assets		21,236			567			—
Deferred tax liabilities:
Operating lease right-of-use asset		(21,234	)		(534	)		—
Capitalized legal fees		(2	)		(33	)		—
Total deferred tax liabilities		(21,236	)		(567	)		—
Total net deferred tax assets	$	—		$	—		$	—

Schedule of Reconciliation of Effective Tax Rate to Statutory U.S. Federal Rate

A reconciliation of the Company’s effective tax rate to the statutory U.S. federal rate is as follows:

	December 31, 2020			December 31, 2019			December 31, 2018
Federal statutory income tax rate		21.0	%		21.0	%		21.0	%
State taxes		4.3			11.0			5.6
Foreign tax rate differential		(7.9	)		(12.4	)		(3.8	)
Change in valuation allowance		(17.3	)		(30.5	)		(18.3	)
Stock-based compensation		6.7			7.7			(0.6	)
Research tax credit		3.8			3.3			1.3
Other		—			(0.1	)		(0.1	)
Sale of future royalties		(9.4	)		—			—
Section 162(m)		(1.2	)		—			—
Fair value adjustments		—			—			(2.4	)
Extinguishment of convertible note		—			—			(2.7	)
Provision for income taxes		0.0	%		0.0	%		0.0	%

Summary of Unrecognized Tax Benefits Amounts

The beginning and ending unrecognized tax benefits amounts are as follows (in thousands):

	December 31, 2020		December 31, 2019		December 31, 2018
Unrecognized tax benefits at beginning of period	$	1,838	$	398	$	357
Increases related to prior year tax positions		—		—		-
Increases related to current year tax positions		2,812		1,440		41
Unrecognized tax benefits at end of period	$	4,650	$	1,838	$	398

Common Stock (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuances

The Company had reserved common stock for future issuances as follows:

	December 31, 2020		December 31, 2019
Exercise of options outstanding and release of restricted shares		7,257,221		6,830,442
Exercise of common stock warrants outstanding		399,999		399,999
Issuance of common stock under the 2018 Equity Incentive Plan		2,742,183		2,118,877
Issuance of common stock under the 2018 Employee Share Purchase Plan		460,000		460,000
Total		10,859,403		9,809,318

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Options Activity Under 2018 Plan and 2015 Plan

Stock option activity under the 2018 Plan and 2015 Plan is summarized as follows:

	Number of Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2019		6,671,542		$	17.90		8.73	$	362,081
Granted		1,068,335		$	55.27
Exercised		(704,675	)	$	8.89
Forfeited or canceled		(137,926	)	$	25.07
Outstanding at December 31, 2020		6,897,276		$	24.52		8.07	$	841,704
Shares exercisable December 31, 2020		3,769,990
Vested and expected to vest December 31, 2020		6,897,276

Fair Value of Employee Stock Options Estimated Using Weighted-average Assumptions

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
Expected volatility		66	%		68	%		59	%
Risk-free interest rate		0.39	%		1.65	%		2.82	%
Dividend yield		0	%		0	%		0	%
Expected term		6.00			5.78			6.06

Fair Value of Non-Employee Stock Options Estimated Using Weighted-average Assumptions

The fair value of non-employee stock options was estimated using the following weighted-average assumptions:

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
Expected volatility		67	%		73	%		68	%
Risk-free interest rate		0.36	%		1.61	%		2.71	%
Dividend yield		0	%		0	%		0	%
Expected term		5.56			6.08			9.30

Summary of Restricted Shares

	Number of Restricted Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2019		160,747		$	60.81
Granted		236,045		$	52.18
Vested		(23,848	)	$	9.21
Shares withheld related to net share settlement of RSUs		(7,999	)	$	9.90
Canceled		(5,000	)	$	72.46
Unvested at December 31, 2020		359,945		$	59.54

Fair Value of Performance Based Awards and RSUs Estimated Using Weighted-average Assumptions

The fair value of performance-based stock options was estimated using the following weighted-average assumptions:

Summary of Stock-based Compensation Classified in Condensed Consolidated Statements of Operations and Comprehensive Loss

Stock-based compensation is classified in the consolidated statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Research and development	$	16,957	$	3,496	$	1,535
General and administrative		13,711		2,614		1,073
Total stock-based compensation	$	30,668	$	6,110	$	2,608

Net Loss per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders

	Year Ended December 31, 2020			Year Ended December 31, 2019			Year Ended December 31, 2018
Numerator:
Net loss attributable to common stockholders	$	(133,096	)	$	(47,365	)	$	(41,443	)
Denominator:
Weighted-average shares outstanding		45,741,845			37,869,291			15,136,197
Less: weighted-average unvested restricted shares and shares subject to repurchase		—			(15,675	)		(159,682	)
Weighted-average shares outstanding used in computing net loss per share attributable to common stockholders, basic and diluted		45,741,845			37,853,616			14,976,515
Net loss per share attributable to common stockholders, basic and diluted	$	(2.91	)	$	(1.25	)	$	(2.77	)

Summary of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss per Share

	Year Ended December 31, 2020		Year Ended December 31, 2019		Year Ended December 31, 2018
Exercise of options outstanding		6,897,276		6,671,542		5,135,267
Unvested restricted shares		359,945		160,747		50,450
Total		7,257,221		6,832,289		5,185,717

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

The following table provides the selected quarterly financial information for the years, 2020 and 2019 (in thousands, except per share data):

	Three Months Ended
	March 31, 2020			June 30, 2020			September 30, 2020			December 31, 2020
Loss from operations	$	(25,723	)	$	(26,779	)	$	(36,663	)	$	(46,842	)
Net loss	$	(24,392	)	$	(25,999	)	$	(36,122	)	$	(46,583	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.54	)	$	(0.58	)	$	(0.80	)	$	(0.97	)

	Three Months Ended
	March 31, 2019			June 30, 2019			September 30, 2019			December 31, 2019
Loss from operations	$	(8,460	)	$	(11,814	)	$	(12,732	)	$	(16,184	)
Net loss	$	(7,984	)	$	(11,385	)	$	(12,380	)	$	(15,616	)
Net loss per share attributable to common stockholders, basic and diluted	$	(0.21	)	$	(0.31	)	$	(0.33	)	$	(0.40	)

The Company - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Oct. 09, 2018	Nov. 30, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net proceeds from initial public offering						$ 83,500
Net proceeds from issuance of common stock				$ 612,016	$ 297,616	$ 83,755
Redeemable Convertible Preferred Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of redeemable convertible preferred stock into common stock, shares						(12,385,154)
Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period				5,972,222	6,900,000	9,400,000
Conversion of 2017 and 2018 convertible notes into common stock, shares						6,932,969
Initial Public Offering \| Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period						9,400,000
Share issued price, per share						$ 10.00
Gross proceeds from initial public offering						$ 94,000
Conversion of redeemable convertible preferred stock into common stock, shares	12,385,154
Initial Public Offering \| Common Stock \| 2017 Convertible Notes
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of 2017 and 2018 convertible notes into common stock, shares	2,637,292
Initial Public Offering \| Common Stock \| 2018 Convertible Notes
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of 2017 and 2018 convertible notes into common stock, shares	4,295,677
Initial Public Offering \| Common Stock \| Redeemable Convertible Preferred Stock \| Warrants Exercised Into Convertible Preferred Shares Then Converted
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Warrants exercised into common stock shares	100,000
Initial Public Offering \| Common Stock \| Redeemable Convertible Preferred Stock \| Warrant
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of preferred stock warrants into common stock warrants, shares	500,000
Follow-On Offering
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross proceeds from issuance of common stock		$ 645,000	$ 317,400
Net proceeds from issuance of common stock		$ 612,000	$ 297,600
Follow-On Offering \| Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period		5,972,222	6,900,000
Share issued price, per share		$ 108.00	$ 46.00		$ 46.00

Summary of Significant Accounting Policies - Additional Information (Details)		12 Months Ended
	Dec. 01, 2019 USD ($)	Dec. 31, 2020 USD ($) Segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)
Summary of Significant Accounting Policies [Line Items]
Foreign currency transaction loss		$ (300,000)		$ (300,000)
Number of reportable segments \| Segment		1
Number of operating segments \| Segment		1
Long-term restricted cash		$ 6,324,000	$ 140,000	$ 140,000
Impairment of long-lived assets		0	0
Unrecognized tax benefits, interest and penalties charged		0
Operating lease right-of-use asset		73,672,000	1,790,000
Operating lease liability		77,402,000
Accounting Standards Update 2016-02
Summary of Significant Accounting Policies [Line Items]
Operating lease right-of-use asset					$ 2,200,000
Operating lease liability					2,300,000
Derecognition of noncurrent deferred liabilities					$ 200,000
ASU 2016-13
Summary of Significant Accounting Policies [Line Items]
Allowance for credit losses for available-for-sale debt securities		$ 0
Baker Bros. Advisors LP \| Funding Agreement
Summary of Significant Accounting Policies [Line Items]
Capped percentage of royalty on future net sales	4.50%
Contractual obligation under funding agreement	$ 225,000,000.0
Laboratory Equipment
Summary of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives of assets		4 years
Computer Equipment and Office Equipment
Summary of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives of assets		3 years
Computer Software
Summary of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives of assets		5 years
Deposited with Financial Institution
Summary of Significant Accounting Policies [Line Items]
Long-term restricted cash		$ 6,300,000	100,000
Maximum
Summary of Significant Accounting Policies [Line Items]
Foreign currency transaction loss			$ (100,000)
Maximum \| Furniture and Fixtures
Summary of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives of assets		7 years
Minimum \| Baker Bros. Advisors LP \| Funding Agreement
Summary of Significant Accounting Policies [Line Items]
Ownership percentage threshold	5.00%
Minimum \| Furniture and Fixtures
Summary of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives of assets		5 years

Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant and Equipment [Line Items]
Total property and equipment	$ 7,306	$ 2,767
Less: Accumulated depreciation	(2,170)	(1,771)
Property and equipment, net	5,136	996
Leasehold Improvement
Property Plant and Equipment [Line Items]
Total property and equipment	1,285	1,265
Laboratory Equipment
Property Plant and Equipment [Line Items]
Total property and equipment	3,351	1,125
Furniture and Fixtures
Property Plant and Equipment [Line Items]
Total property and equipment	214	204
Computer Hardware
Property Plant and Equipment [Line Items]
Total property and equipment	31
Computer Software
Property Plant and Equipment [Line Items]
Total property and equipment	89	79
Office Equipment
Property Plant and Equipment [Line Items]
Total property and equipment	107	$ 94
Construction in Progress
Property Plant and Equipment [Line Items]
Total property and equipment	$ 2,229

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation	$ 477	$ 538	$ 490

Accrued Liabilities and Other Current Liabilities - Schedule of Accrued Liabilities and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Payable And Accrued Liabilities Current [Abstract]
Accrued clinical trial and related costs	$ 11,119	$ 4,056
Accrued research and development	3,082	838
Accrued salaries and benefits	5,094	3,108
Accrued legal fees	252	302
Accrued professional fees	253	195
Accrued other liabilities	602	159
Total accrued and other current liabilities	$ 20,402	$ 8,658

Fair Value Measurements - Summary of Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	$ 942,063	$ 347,643
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	917,485	155,276
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	10,006	50,185
Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	14,572	51,662
Repurchase Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		50,000
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		5,987
Marketable securities		34,533
Quoted Price in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	917,485	205,276
Quoted Price in Active Markets (Level 1) \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	917,485	155,276
Quoted Price in Active Markets (Level 1) \| U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Quoted Price in Active Markets (Level 1) \| Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Quoted Price in Active Markets (Level 1) \| Repurchase Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		50,000
Quoted Price in Active Markets (Level 1) \| Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		0
Marketable securities		0
Significant Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	24,578	142,367
Significant Observable Inputs (Level 2) \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Significant Observable Inputs (Level 2) \| U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	10,006	50,185
Significant Observable Inputs (Level 2) \| Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	14,572	51,662
Significant Observable Inputs (Level 2) \| Repurchase Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		0
Significant Observable Inputs (Level 2) \| Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		5,987
Marketable securities		34,533
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	0	0
Significant Unobservable Inputs (Level 3) \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Significant Unobservable Inputs (Level 3) \| U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Significant Unobservable Inputs (Level 3) \| Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 0	0
Significant Unobservable Inputs (Level 3) \| Repurchase Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		0
Significant Unobservable Inputs (Level 3) \| Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents		0
Marketable securities		$ 0

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Transfers of assets or liabilities between the fair value measurement levels	$ 0	$ 0
Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liability measured at fair value	0	0
Nonrecurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Liability measured at fair value	$ 0	$ 0

Marketable Securities - Summary of Marketable Securities Held (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Amortized Cost, current	$ 24,525	$ 124,678
Unrealized Gains, current	53	14
Unrealized Losses, current		(8)
Fair Value, current	24,578	124,684
Amortized Cost, noncurrent		11,692
Unrealized Gains, noncurrent		4
Fair Value, noncurrent		11,696
U.S. Treasury Securities
Marketable Securities [Line Items]
Amortized Cost, current	10,003	50,190
Unrealized Gains, current	3
Unrealized Losses, current		(5)
Fair Value, current	10,006	50,185
Commercial Paper
Marketable Securities [Line Items]
Amortized Cost, current		34,532
Unrealized Gains, current		1
Fair Value, current		34,533
Corporate Notes
Marketable Securities [Line Items]
Amortized Cost, current	14,522	39,956
Unrealized Gains, current	50	13
Unrealized Losses, current		(3)
Fair Value, current	$ 14,572	39,966
Amortized Cost, noncurrent		11,692
Unrealized Gains, noncurrent		4
Fair Value, noncurrent		$ 11,696

Marketable Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($)
Marketable Securities [Line Items]
Realized gains or losses recognized on sale or maturity of available-for-sale debt securities	$ 0
Marketable securities with unrealized losses	$ 0
Maximum
Marketable Securities [Line Items]
Marketable securities, contractual maturities	1 year

Commitments and Contingencies - Additional Information (Details) SFr in Thousands, ft² in Millions	1 Months Ended					12 Months Ended
	Aug. 31, 2020 CHF (SFr)	Jun. 30, 2020 USD ($) ft² Building	Apr. 30, 2020 CHF (SFr) m²	Mar. 31, 2016 USD ($)	May 31, 2013 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jul. 01, 2020 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Operating lease right-of-use asset						$ 73,672,000	$ 1,790,000
Lease liabilities						77,402,000
Current portion of tenant improvement allowance payable						20,402,000	8,658,000
Other liabilities, non-current portion of tenant Improvement allowance payable						256,000	295,000
Tenant Improvement Allowance Payable
Commitments And Contingencies Disclosure [Line Items]
Other liabilities, non-current portion of tenant Improvement allowance payable						300,000	300,000
Purchase Commitments
Commitments And Contingencies Disclosure [Line Items]
Noncancellable purchase commitments, including potential cancellation fees						500,000	700,000
Lonza \| Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Cancelable and/ or non-cancelable contractual obligations, total						$ 242,300,000	4,700,000
Contractual obligation period						10 years
Unrecorded unconditional purchase obligation, expenses recognized						$ 16,800,000	7,900,000	$ 2,800,000
Unrecorded unconditional purchase obligation, cancellation fees						0
Maximum \| Tenant Improvement Allowance Payable
Commitments And Contingencies Disclosure [Line Items]
Current portion of tenant improvement allowance payable						100,000	$ 100,000
Maximum \| Cancellable Assignment and License Agreement
Commitments And Contingencies Disclosure [Line Items]
Milestone payments						33,200,000
Clinical and Commercial Supply of Drug Substance \| Manufacturing Agreement
Commitments And Contingencies Disclosure [Line Items]
Estimated capital contribution \| SFr	SFr 40,000
Annual suite fees payment for 2021 \| SFr	12,000
Annual suite fees payment each year after 2021 \| SFr	SFr 16,000
Manufacturing agreement initial term	8 years
Clinical and Commercial Supply of Drug Substance \| Maximum \| Manufacturing Agreement
Commitments And Contingencies Disclosure [Line Items]
Manufacturing agreement term that can be extended	16 years
Leasehold Improvements \| California
Commitments And Contingencies Disclosure [Line Items]
Improvements allowance payable to be drawn				$ 400,000
Interest rate				8.00%
Lease term				Oct. 31, 2023
Debt instrument term				10 years
Lease Agreement on June 2020 \| California
Commitments And Contingencies Disclosure [Line Items]
Number of buildings leased \| Building		2
Cash-collateralized letter of credit		$ 10,900,000							$ 6,200,000
Lease Agreement on June 2020 \| 1200 Page Mill Road in Palo Alto \| California
Commitments And Contingencies Disclosure [Line Items]
Lease area \| ft²		82,662
Initial lease term		6 years 6 months
Monthly rent expense		$ 600,000
Annual rent year-over-year increase percentage		3.00%
Total rent abatement		$ 7,200,000
Lessee operating lease option to extend		6.5 years
Tenant improvement allowance		$ 1,200,000
Lease Agreement on June 2020 \| 1250 Page Mill Road in Palo Alto \| California
Commitments And Contingencies Disclosure [Line Items]
Lease area \| ft²		72,812
Initial lease term		13 years
Monthly rent expense		$ 500,000
Annual rent year-over-year increase percentage		3.00%
Total rent abatement		$ 6,300,000
Lessee operating lease option to extend		5 years
Tenant improvement allowance		$ 10,600,000
Number of options to extend lease term		2
Lease Agreement on April 2020 \| Rottenstrasse 5 in Visp \| Switzerland
Commitments And Contingencies Disclosure [Line Items]
Lease area \| m²			1,000
Initial lease term			5 years
Monthly rent expense \| SFr			SFr 32
Automatic renewal interval			5 years
Lease Agreement on April 2020 \| Rottenstrasse 5 in Visp \| Switzerland \| Maximum
Commitments And Contingencies Disclosure [Line Items]
Lessee, operating lease, term of contract			15 years
Lease Agreement on April and June 2020
Commitments And Contingencies Disclosure [Line Items]
Operating lease right-of-use asset						0
Lease liabilities						$ 0
Tenant Improvement Allowance Agreement \| Leasehold Improvements \| California
Commitments And Contingencies Disclosure [Line Items]
Improvements allowance payable to be drawn					$ 300,000
Interest rate					8.00%
Lease term					Oct. 31, 2018

Commitments and Contingencies - Summary of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Operating Lease
2021	$ 4,288
2022	7,660
2023	14,598
2024	15,037
2025	15,475
Thereafter	71,462
Total undiscounted lease payments	128,520
Less: imputed interest	(51,118)
Total operating lease liabilities	$ 77,402

Commitments and Contingencies - Summary of Lessee, Weighted Average Remaining Lease Term and Weighted Average Discount Rates (Details)	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Weighted-average remaining lease term (in years)	9 years 6 months	3 years 9 months 18 days
Weighted-average discount rate	6.70%	8.50%

Income Taxes - Schedule of Provision (Benefit) for Income Taxes (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Current:
Foreign	$ 14
Total current	14
Deferred:
Provision (Benefit) for income taxes	$ 14

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Income Taxes - Components of Loss before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States	$ (17,273)	$ 2,633	$ (17,273)
Foreign	(115,809)	(49,998)	(24,170)
Total loss before income taxes	$ (133,082)	$ (47,365)	$ (41,443)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 940
-SubTopic 20
-Section 25
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-URI http://asc.fasb.org/extlink&oid=68072869&loc=d3e41242-110953

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 942
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
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Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

+ Details

Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 28,451	$ 18,523	$ 11,044
Intangible assets	12,088	12,112	7,588
Research and development tax credits	10,527	4,037	1,559
Stock-based compensation	8,405	1,539	394
Accruals	1,367	885	700
Operating lease liability	22,276	577	0
Property and equipment	127	143	109
Total deferred tax assets	83,241	37,816	21,394
Valuation allowance	(62,005)	(37,249)	(21,394)
Net deferred tax assets	21,236	567	0
Deferred tax liabilities:
Operating lease right-of-use asset	(21,234)	(534)	0
Capitalized legal fees	(2)	(33)	0
Total deferred tax liabilities	$ (21,236)	(567)	0
Total net deferred tax assets		$ 0	$ 0

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Increase in valuation allowance	$ 24,800	$ 15,900	$ 8,200
Research and development credit carryforwards	10,527	$ 4,037	$ 1,559
Federal
Income Taxes [Line Items]
Net operating loss	$ 50,100
Net operating loss carryforwards expiration start year	2035
Research and development credit carryforwards	$ 10,200
Tax credit carryforwards expiration start year	2035
Number of periods open for examination	3 years
Federal \| Net Operating Loss Not Subject to Expiration
Income Taxes [Line Items]
Net operating loss	$ 32,000
State
Income Taxes [Line Items]
Net operating loss	$ 171,000
Net operating loss carryforwards expiration start year	2035
Research and development credit carryforwards	$ 4,900
Number of periods open for examination	4 years
California
Income Taxes [Line Items]
Tax credit carryforward, expiration year	indefinitely

Income Taxes - Schedule of Reconciliation of Effective Tax Rate to Statutory U.S. Federal Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes	4.30%	11.00%	5.60%
Foreign tax rate differential	(7.90%)	(12.40%)	(3.80%)
Change in valuation allowance	(17.30%)	(30.50%)	(18.30%)
Stock-based compensation	6.70%	7.70%	(0.60%)
Research tax credit	3.80%	3.30%	1.30%
Other		(0.10%)	(0.10%)
Sale of future royalties	(9.40%)
Section 162(m)	(1.20%)
Fair value adjustments			(2.40%)
Extinguishment of convertible note			(2.70%)
Provision for income taxes	0.00%	0.00%	0.00%

Income Taxes - Summary of Unrecognized Tax Benefits Amounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of period	$ 1,838	$ 398	$ 357
Increases related to prior year tax positions	0	0	0
Increases related to current year tax positions	2,812	1,440	41
Unrecognized tax benefits at end of period	$ 4,650	$ 1,838	$ 398

Preferred Stock - Additional Information (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Maximum
Class Of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000

Common Stock - Additional Information (Details)	12 Months Ended
Common Stock - Additional Information (Details)	Dec. 31, 2020 Vote $ / shares shares	Dec. 31, 2019 Vote $ / shares shares
Equity [Abstract]
Common stock, shares authorized \| shares	490,000,000	490,000,000
Common stock, par value \| $ / shares	$ 0.0001	$ 0.0001
Common stock, number of vote per share \| Vote	1	1

Common Stock - Schedule of Common Stock Reserved for Future Issuances (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Common stock reserved for future issuances	10,859,403	9,809,318
Stock Options Outstanding and Release of Restricted Shares
Class Of Stock [Line Items]
Common stock reserved for future issuances	7,257,221	6,830,442
2018 Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for future issuances	2,742,183	2,118,877
2018 Employee Share Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for future issuances	460,000	460,000
Warrant
Class Of Stock [Line Items]
Common stock reserved for future issuances	399,999	399,999

Stock-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 30,668,000	$ 6,110,000	$ 2,608,000
Common stock, shares reserved for issuance	10,859,403	9,809,318
Unrecognized stock-based compensation expense	$ 91,400,000
Unrecognized stock-based compensation weighted-average period expected for recognition	2 years 10 months 24 days
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, weighted-average grant date fair value	$ 32.44	$ 34.11	$ 4.36
Dividends paid	$ 0
Expected dividend payment	$ 0
Dividend yield	0.00%	0.00%	0.00%
Total fair value of employee options vested	$ 19,700,000	$ 4,600,000	$ 1,200,000
Stock-based compensation expense recognized	$ 20,800,000	$ 5,700,000	$ 2,000,000.0
Non-employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Stock options, granted	41,500	15,000	215,000
Options Granted to Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 700,000	$ 100,000	$ 400,000
Restricted Stock Awards (RSAs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period	4 years
Stock-based compensation expense recognized		100,000	200,000
Stock-based compensation of total fair value vested		$ 100,000	200,000
Stock units, granted	236,045
Awards vested	23,848
Weighted-average grant date fair value	$ 59.54	$ 60.81
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period	4 years
Stock-based compensation expense recognized	$ 1,900,000	$ 300,000
Stock-based compensation of total fair value vested	$ 300,000	300,000
Stock units, granted	236,045
Restricted Stock Units (RSUs) \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized			$ 100,000
Performance Based Equity Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized	$ 7,200,000	$ 100,000
Stock options, granted	0
Vesting period	These performance-based equity awards will vest one-quarter upon the achievement of specific clinical development milestones. The remaining shares will then vest in three equal annual installments after that date.
Awards vested	0	0
Performance-based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Dividend yield		0.00%
Weighted-average grant date fair value		$ 47.89
Performance Based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value		$ 73.51
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares increases annually	1,776,761
Awards vesting period	4 years
Number of shares available for grant	2,742,183
2018 Equity Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares increases annually	4,300,000
Percentage of outstanding stock	4.00%
2018 Equity Incentive Plan \| Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance	4,300,000
2018 Equity Incentive Plan \| Incentive Stock Options \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, periods granted	10 years
2018 Equity Incentive Plan \| ISO Granted to a Greater than 10% Stockholder \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options, periods granted	5 years
Options exercise price, percentage of estimated fair value of shares on grant date	110.00%
2018 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance	460,000

Stock-Based Compensation - Summary of Stock Options Activity Under 2018 Plan and 2015 Plan (Details) - 2018 Plan and 2015 Equity Incentive Plan - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Options
Beginning balance	6,671,542
Granted	1,068,335
Exercised	(704,675)
Forfeited or canceled	(137,926)
Ending balance	6,897,276	6,671,542
Shares exercisable	3,769,990
Vested and expected to vest	6,897,276
Weighted Average Exercise Price
Beginning balance	$ 17.90
Granted	55.27
Exercised	8.89
Forfeited or canceled	25.07
Ending balance	$ 24.52	$ 17.90
Weighted Average Remaining Contractual Term (in years)
Weighted Average Remaining Contractual Term (in years)	8 years 25 days	8 years 8 months 23 days
Aggregate Intrinsic Value
Beginning balance	$ 841,704	$ 362,081

Stock-Based Compensation - Fair Value of Employee Stock Options Estimated Using Weighted-average Assumptions (Details) - Employee Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	66.00%	68.00%	59.00%
Risk-free interest rate	0.39%	1.65%	2.82%
Dividend yield	0.00%	0.00%	0.00%
Expected term	6 years	5 years 9 months 10 days	6 years 21 days

Stock-Based Compensation - Fair Value of Non-employee Stock Options Estimated Using Weighted-average Assumptions (Details) - Non-employee Stock Options	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	67.00%	73.00%	68.00%
Risk-free interest rate	0.36%	1.61%	2.71%
Dividend yield	0.00%	0.00%	0.00%
Expected term	5 years 6 months 21 days	6 years 29 days	9 years 3 months 18 days

Stock-Based Compensation - Summary of Restricted Shares (Details) - Restricted Stock Awards (RSAs)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Number of Restricted Shares
Unvested, beginning balance \| shares	160,747
Granted \| shares	236,045
Vested \| shares	(23,848)
Shares withheld related to net share settlement of RSUs \| shares	(7,999)
Canceled \| shares	(5,000)
Unvested, ending balance \| shares	359,945
Weighted Average Grant Date Fair Value
Unvested, beginning balance \| $ / shares	$ 60.81
Granted \| $ / shares	52.18
Vested \| $ / shares	9.21
Shares withheld related to net share settlement of RSUs \| $ / shares	9.90
Canceled \| $ / shares	72.46
Unvested, ending balance \| $ / shares	$ 59.54

Stock-Based Compensation - Fair Value of Performance-based Stock Options Estimated Using Weighted-average Assumptions (Details) - Performance-based Stock Options	12 Months Ended
	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	72.00%
Risk-free interest rate	1.67%
Dividend yield	0.00%
Expected term	6 years 3 months 21 days

Stock-Based Compensation - Summary of Stock-based Compensation Classified in Condensed Consolidated Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 30,668	$ 6,110	$ 2,608
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	16,957	3,496	1,535
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 13,711	$ 2,614	$ 1,073

Net Loss per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss	$ (46,583)	$ (36,122)	$ (25,999)	$ (24,392)	$ (15,616)	$ (12,380)	$ (11,385)	$ (7,984)	$ (133,096)	$ (47,365)	$ (41,443)
Denominator:
Weighted-average shares outstanding									45,741,845	37,869,291	15,136,197
Less: weighted-average unvested restricted shares and shares subject to repurchase									0	(15,675)	(159,682)
Weighted-average common shares outstanding used in computing net loss per common share, basic and diluted									45,741,845	37,853,616	14,976,515
Net loss per share attributable to common stockholders, basic and diluted	$ (0.97)	$ (0.80)	$ (0.58)	$ (0.54)	$ (0.40)	$ (0.33)	$ (0.31)	$ (0.21)	$ (2.91)	$ (1.25)	$ (2.77)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Net Loss per Share Attributable to Common Stockholders - Summary of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	7,257,221	6,832,289	5,185,717
Employee Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	6,897,276	6,671,542	5,135,267
Unvested Restricted Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	359,945	160,747	50,450

401(k) Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Plan name	401(k)
Defined Contribution Plan, Plan Name [Extensible List]	kod:RetirementAndSavingsPlanMember
Employer matching contribution, percent of match	100.00%
Expense related to matching contributions	$ 0.6	$ 0.3
IRS
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution cap on employee contribution limit	50.00%

Liability Related to Sale of Future Royalties - Additional Information (Details) - USD ($)			12 Months Ended
	Feb. 04, 2020	Dec. 01, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 29, 2020
Related Party Transaction [Line Items]
Proceeds from sale of future royalties			$ 99,643,000	$ 0	$ 0
Liability related to sale of future royalties			99,890,000
Baker Bros. Advisors LP \| Funding Agreement
Related Party Transaction [Line Items]
Capped percentage of royalty on future net sales		4.50%
Contractual obligation under funding agreement		$ 225,000,000.0
Percentage of repurchase of royalties		100.00%
Proceeds from sale of future royalties	$ 100,000,000.0
Funds to be payable upon enrollment of patients						$ 125,000,000.0
Percentage of patients to be enrolled						50.00%
Liability related to sale of future royalties			100,000,000.0
Interest expense, liability related to sale of future royalties			$ 0
Baker Bros. Advisors LP \| Funding Agreement \| Minimum
Related Party Transaction [Line Items]
Ownership percentage		5.00%

Selected Quarterly Financial Data - Schedule of Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Loss from operations	$ (46,842)	$ (36,663)	$ (26,779)	$ (25,723)	$ (16,184)	$ (12,732)	$ (11,814)	$ (8,460)	$ (136,007)	$ (49,190)	$ (26,374)
Net loss	$ (46,583)	$ (36,122)	$ (25,999)	$ (24,392)	$ (15,616)	$ (12,380)	$ (11,385)	$ (7,984)	$ (133,096)	$ (47,365)	$ (41,443)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.97)	$ (0.80)	$ (0.58)	$ (0.54)	$ (0.40)	$ (0.33)	$ (0.31)	$ (0.21)	$ (2.91)	$ (1.25)	$ (2.77)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details