Kodiak Sciences (KOD) 10-K 1 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2021	Feb. 18, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
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		51,934,500
Entity Public Float			$ 3.1
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	San Jose, California
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive Proxy Statement relating to the 2022 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, 2021 .

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 731,510	$ 944,396
Marketable securities	0	24,578
Prepaid expenses and other current assets	3,301	3,031
Total current assets	734,811	972,005
Restricted cash	6,324	6,324
Property and equipment, net	41,330	5,136
Operating lease right-of-use asset	66,744	73,672
Other assets	55,011	10,210
Total assets	904,220	1,067,347
Current liabilities:
Accounts payable	12,431	8,646
Accrued and other current liabilities	48,319	20,402
Operating lease liability	3,933	2,374
Total current liabilities	64,683	31,422
Operating lease liability, net of current portion	76,063	75,028
Liability related to sale of future royalties	99,943	99,890
Other liabilities	211	256
Total liabilities	240,900	206,596
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, 2021 and December 31, 2020, respectively	0	0
Common stock, $0.0001 par value, 490,000,000 shares authorized at December 31, 2021 and December 31, 2020; 51,826,257 and 51,112,302 shares issued and outstanding at December 31, 2021 and December 31, 2020, respectively	5	5
Additional paid-in capital	1,221,532	1,151,920
Accumulated other comprehensive income	0	53
Accumulated deficit	(558,217)	(291,227)
Total stockholders’ equity	663,320	860,751
Total liabilities and stockholders’ equity	$ 904,220	$ 1,067,347

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
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	51,826,257	51,112,302
Common stock, shares outstanding	51,826,257	51,112,302

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating expenses
Research and development	$ 217,340	$ 107,389	$ 37,506
General and administrative	49,711	28,618	11,684
Total operating expenses	267,051	136,007	49,190
Loss from operations	(267,051)	(136,007)	(49,190)
Interest income	298	2,902	1,568
Interest expense	(22)	(25)	(8)
Other income (expense), net	(215)	34	265
Net loss	$ (266,990)	$ (133,096)	$ (47,365)
Net loss per common share, basic and diluted	$ (5.16)	$ (2.91)	$ (1.25)
Weighted-average shares of common stock outstanding used in computing net loss per common share, basic and diluted	51,788,918	45,741,845	37,853,616
Other comprehensive income (loss)
Change in unrealized gains related to available-for-sale debt securities, net of tax	$ (53)	$ 43	$ 10
Total other comprehensive income (loss)	(53)	43	10
Comprehensive loss	$ (267,043)	$ (133,053)	$ (47,355)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning Balance at Dec. 31, 2018	$ 86,833	$ 4	$ 197,595		$ (110,766)
Beginning 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
Issuance of common stock upon vesting of restricted stock units, net of taxes withheld	(132)		(132)
Issuance of common stock upon 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 follow-on offering, net of offering costs	297,616	$ 1	297,615
Issuance of common stock in connection with 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
Issuance of common stock upon vesting of restricted stock units, net of taxes withheld	(487)		(487)
Issuance of common stock upon vesting of restricted stock units, net of taxes withheld, shares		22,001
Issuance of common stock in connection with follow-on offering, net of offering costs	612,016		612,016
Issuance of common stock in connection with 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
Issuance of common stock upon exercise of stock options	7,743		7,743
Issuance of common stock upon exercise of stock options, shares		463,796
Issuance of common stock pursuant to employee stock purchase plans	484		484
Issuance of common stock upon vesting of restricted stock units, net of taxes withheld, shares		93,218
Issuance of common stock pursuant to employee stock purchase plans, shares		6,958
Issuance of common stock upon exercise of common stock warrants, shares		149,983
Stock-based compensation expense	61,385		61,385
Other comprehensive income	(53)			$ (53)
Net loss	(266,990)				(266,990)
Ending Balance at Dec. 31, 2021	$ 663,320	$ 5	$ 1,221,532		$ (558,217)
Ending balance, shares at Dec. 31, 2021		51,826,257

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
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

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net loss	$ (266,990,000)	$ (133,096,000)	$ (47,365,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,003,000	477,000	538,000
Loss on disposal of long-lived asset	120,000
Stock-based compensation	6,138,500	30,668,000	6,110,000
Amortization (accretion) of premium (discount) on marketable securities	25,000	(51,000)	(241,000)
Amortization of operating lease right-of-use asset	7,708,000	3,731,000	373,000
Amortization of issuance costs	53,000	49,000
Changes in assets and liabilities:
Prepaid expenses and other current assets	(270,000)	(218,000)	(168,000)
Other assets	1,465,000	(1,814,000)	(4,511,000)
Accounts payable	(2,094,000)	5,224,000	1,569,000
Accrued and other current liabilities	13,511,000	11,748,000	4,932,000
Operating lease liability	1,814,000	(146,000)	(383,000)
Net cash used in operating activities	(182,270,000)	(83,428,000)	(39,146,000)
Cash flows from investing activities
Purchase of property and equipment	(17,032,000)	(3,814,000)	(437,000)
Deposits on property and equipment	(46,266,000)	(3,184,000)
Purchase of marketable securities	0	(86,317,000)	(150,961,000)
Maturities of marketable securities	24,500,000	198,149,000	14,400,000
Net cash provided by (used in) investing activities	(38,798,000)	104,834,000	(136,998,000)
Cash flows from financing activities
Proceeds from issuance of common stock in connection with offering, net of offering costs		612,016,000	297,616,000
Proceeds from issuance of common stock upon options exercise	7,743,000	6,248,000	2,287,000
Payments for restricted stock units, net of taxes withheld	0	(487,000)	(132,000)
Proceeds from issuance of common stock pursuant to employee stock purchase plans	484,000	0
Proceeds from sale of future royalties, net of issuance costs	0	99,643,000
Principal payments of capital lease	0	(5,000)	(48,000)
Principal payments of tenant improvement allowance payable	(45,000)	(38,000)	(36,000)
Net cash provided by financing activities	8,182,000	717,377,000	299,687,000
Net increase (decrease) in cash, cash equivalents and restricted cash	(212,886,000)	738,783,000	123,543,000
Cash, cash equivalents and restricted cash, at beginning of period	950,720,000	211,937,000	88,394,000
Cash, cash equivalents and restricted cash, at end of period	737,834,000	950,720,000	211,937,000
Reconciliation of cash, cash equivalents and restricted cash to consolidated balance sheets
Cash and cash equivalents	731,510,000	944,396,000	211,797,000
Restricted cash	6,324,000	6,324,000	140,000
Cash, cash equivalents and restricted cash, at end of period	737,834,000	950,720,000	211,937,000
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	22,000	25,000	8,000
Supplemental disclosures of non-cash investing and financing information:
Operating lease right-of-use asset obtained in exchange for operating lease liability	773,000	75,614,000	2,163,000
Purchase of property and equipment under accounts payable and accruals	21,088,000	803,000
Reclassification of deposits to property and equipment	2,370,000
Unpaid offering costs		$ 238,000	$ 459,000

The Company

The Company	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	1. The Company Kodiak Sciences Inc. (the “Company”) is a biopharmaceutical company specializing in novel therapeutics to treat high-prevalence retinal diseases. The Company devotes substantially all of its time and efforts to performing research and development, raising capital and recruiting personnel. 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 Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
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, $ 0.3 million, and less than $ 0.1 million for the years ended December 31, 2021, 2020 and 2019 , 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 retinal 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, 2021 and 2020 , cash, cash equivalents and marketable securities were invested primarily in money market funds, U.S. treasury securities 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 may invest 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 can 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, 2021, and 2020, the Company had $ 6.3 million and $ 6.3 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. Construction in progress reflects amounts incurred for construction or improvements of property or equipment that have not been placed in service. 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 am ount 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, 2021 and 2020. 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 or the Monte Carlo simulation model, which requires the input of subjective assumptions, including (i) the calculation of expected term of the award, (ii) the expected stock price volatility, (iii) the risk-free interest rate, and (iv) expected dividends. 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, and equals the midpoint between the vesting date and maximum contractual expiration date. The expected volatility is estimated based on the Company's historical information for its common stock and supplemented by the historical stock price volatility of a representative peer group over a period equivalent to the expected term of the equity award. The risk-free interest rate is estimated based on the U.S. Treasury securities with maturity dates commensurate with the expected term of the equity award. The Company has never paid, and does not expect to pay, dividends in the foreseeable future. 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. Refer to Note 11. 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. In July 2021, the funding agreement was amended, at the Company’s request, that the remaining funding amount of $ 125.0 million would no t be paid. 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. 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 a ccounting p ronouncements 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. There have been no new accounting pronouncements issued nor adopted during the year ended December 31, 2021 that are of significance to the Company.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
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, December 31, Leasehold improvement $ 1,285 $ 1,285 Laboratory equipment 4,565 3,351 Furniture and fixtures 214 214 Computer hardware 200 31 Computer software 89 89 Office equipment 107 107 Construction in progress 37,809 2,229 Total property and equipment 44,269 7,306 Less: Accumulated depreciation ( 2,939 ) ( 2,170 ) Property and equipment, net $ 41,330 $ 5,136 All property and equipment are maintained in the United States and Switzerland. Depreciation expense, including depreciation of assets under capital leases, was $ 1.0 million, $ 0.5 million and $ 0.5 million for the years ended December 31, 2021, 2020 and 2019 , respectively.

Accrued Liabilities and Other C

Accrued Liabilities and Other Current Liabilities	12 Months Ended
	Dec. 31, 2021
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, December 31, Accrued clinical trial and related costs $ 21,776 $ 11,119 Accrued leasehold improvements 13,021 19 Accrued salaries and benefits 6,187 5,094 Accrued research and development 6,041 3,082 Accrued legal fees 403 252 Accrued professional fees 176 253 Accrued other liabilities 715 583 Total accrued and other current liabilities $ 48,319 $ 20,402

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
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, 2021 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 706,703 $ — $ — $ 706,703 Total $ 706,703 $ — $ — $ 706,703 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 As of December 31, 2021 and 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 transfers of assets or liabilities between the fair value measurement levels during the years ended December 31, 2021 and 2020 .

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2021
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 Company had no marketable securities at December 31 , 2021 . The following table summarizes the marketable securities (in thousands): As of December 31, 2020 Amortized Unrealized Unrealized Fair 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 All marketable securities held at December 31, 2020 had effective maturities of less than one year . There were no marketable securities with unrealized losses as of December 31 , 2020 . The Company did no t realized any gains or losses recognized on the sale or maturity of available-for-sale debt securities during the year ended December 31 , 2021 and as a result, the Company did not reclassify any amounts out of accumulated comprehensive loss. There were no impairment charges or recoveries recorded during the years ended December 31, 2021 and 2020 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
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 in 2020. 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. As of December 31, 2021, the Company received a tenant improvement allowance of $ 1.4 million. 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 32.0 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, 2021 were as follows (in thousands): Year ending December 31, As of 2022 $ 7,306 2023 14,531 2024 15,023 2025 15,461 2026 15,912 Thereafter 55,486 Total undiscounted lease payments 123,719 Less: imputed interest ( 33,360 ) Less: future tenant improvement reimbursements ( 10,363 ) Total operating lease liabilities $ 79,996 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, December 31, Weighted-average remaining lease term (in years) 8.8 9.5 Weighted-average discount rate 6.7 % 6.7 % Embedded Lease In August 2020, the Company and its wholly-owned subsidiary Kodiak Sciences GmbH entered into a manufacturing agreement with Lonza Ltd (“Lonza”) for the clinical and commercial supply of drug substance for KSI-301. A custom-built manufacturing facility is planned to be completed and dedicated to the manufacture of the Company’s drug substance. 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 and Lonza each have the ability to terminate this agreement upon the occurrence of certain conditions. In April 2021, the agreement was amended to provide for higher annual manufacturing capacity. The Company expanded and finalized the design and scope of the bioconjugate manufacturing facility with a revised estimated capital contribution of approximately 75.0 million Swiss Francs of which the Company has paid 35.0 million Swiss Francs of the capital contribution, equivalent to $ 38.7 million U.S. Dollars, which is recorded in other assets on the consolidated balance sheet as of December 31, 2021 . Over the period from 2022 through 2029, manufacturing payments totaling approximately 150.0 million Swiss Francs may be incurred for potential commercial supply of KSI-301 drug substance. These commitments are not included in the operating lease liabilities table above. 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, 2021 , the Company did not have control of this manufacturing space and therefore, did no t record a right-of-use asset and corresponding lease liability. Manufacturing Agreements The Company has entered into service and equipment purchase agreements in the normal course of business with various providers, pursuant to which such providers agreed to perform activities in connection with the manufacturing process of certain materials. These agreements, and any related amendments, state that planned activities and purchases 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. As of December 31, 2021 and 2020, the total amount of contractual obligations related to these manufacturing agreements that are subject to cancellation fees, including accrued amounts, were $ 69.5 million and $ 56.5 million, respectively. These amounts represent our minimal contractual obligations, excluding the commitments under the embedded lease arrangement. Purchases under these manufacturing agreements for the years ended December 31, 2021, 2020 and 2019 were $ 31.8 million, $ 16.8 million and $ 7.9 million, respectively. As of December 31, 2021 , the Company had no t incurred any cancellation fees under the manufacturing agreements. 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. 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 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, 2021 and 2020 , 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, 2021 and 2020 , the non-current portion of the tenant improvement allowance payable in other liabilities was $ 0.2 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

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes The components of loss before income taxes were as follows (in thousands): Year Ended December 31, 2021 Year Ended December 31, Year Ended December 31, United States $ ( 46,590 ) $ ( 17,273 ) $ 2,633 Foreign ( 220,326 ) ( 115,809 ) ( 49,998 ) Total loss before income taxes $ ( 266,916 ) $ ( 133,082 ) $ ( 47,365 ) The provision (benefit) for income taxes consists of the following (in thousands): Year Ended December 31, 2021 Year Ended December 31, Year Ended December 31, Current: Federal $ — $ — $ — State — — — Foreign 74 14 — Total current 74 14 — Deferred: Federal — — — State — — — Foreign — — — Total deferred — — — Provision (Benefit) for income taxes $ 74 $ 14 $ — 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, 2021 December 31, December 31, Deferred tax assets: Net operating loss carryforwards $ 75,259 $ 28,451 $ 18,523 Intangible assets 166,269 12,088 12,112 Research and development tax credits 18,330 10,527 4,037 Stock-based compensation 10,823 8,405 1,539 Accruals 1,532 1,367 885 Operating lease liability 23,142 22,276 577 Property and equipment — 127 143 Total deferred tax assets 295,355 83,241 37,816 Valuation allowance ( 275,788 ) ( 62,005 ) ( 37,249 ) Net deferred tax assets 19,567 21,236 567 Deferred tax liabilities: Operating lease right-of-use asset ( 19,217 ) ( 21,234 ) ( 534 ) Capitalized legal fees — ( 2 ) ( 33 ) Property and equipment ( 350 ) — — Total deferred tax liabilities ( 19,567 ) ( 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, 2021, 2020 and 2019 was an increase of approximately $ 213.8 million, $ 24.8 million and $ 15.9 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. The Company has completed a Section 382 study through December 31, 2020 which concluded no such ownership change had occurred through December 31, 2020. Subsequent ownership changes since the most recent study may further affect the limitation in future years. As of December 31, 2021 , the Company had $ 57.5 million of federal and $ 395.4 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. $ 39.4 million of the federal net operating loss are not subject to expiration. As of December 31, 2021 , the Company also had federal and state research and development credit carryforwards of $ 17.9 million and $7.2 million, respectively. The federal research and development credit carryforwards expire beginning 2035 . The California tax credit can be carried forward indefinitely. On March 27, 2020, the President signed into law the Coronavirus Aid, Relief, and Economic Security Act, or the CARES Act, an economic stimulus package in response to the COVID-19 global pandemic and the Families First Coronavirus Response Act, or FFCR Act, which permits employees of certain organizations paid sick time stemming from COVID-19-related issues. The CARES Act contains several corporate income tax provisions, including making remaining alternative minimum tax credits immediately refundable; providing a 5-year carryback of NOLs generated in tax years 2018, 2019, and 2020, and removing the 80% taxable income limitation on utilization of those NOLs if carried back to prior tax years or utilized in tax years beginning before 2021; temporarily liberalizing the interest deductibility rules under Section 163(j) of the CARES Act, by raising the adjusted taxable income limitation from 30% to 50% for tax years 2019 and 2020 and giving taxpayers the election of using 2019 adjusted taxable income for purposes of computing 2020 interest deductibility . The CARES Act did not have a material impact on the Company’s tax provision for the years ended December 31, 2020 or 2021. The Consolidated Appropriations Act, 2021, which was enacted on December 27, 2020, has expanded, extended, and clarified selected CARES Act provisions, specifically on Paycheck Protection Program loans and Employee Retention Tax Credits, 100% deductibility of business meals as well as other tax extenders. The Consolidated Appropriations Act did not have a material impact on the Company’s tax provision for the years ended December 31, 2020 or 2021. California Assembly Bill 85 (AB 85) was signed into law by Governor Gavin Newsom on June 29, 2020. The legislation suspends the California NOL deductions for 2020, 2021, and 2022 for certain taxpayers and imposes a limitation on certain California tax credits for 2020, 2021, and 2022. The legislation disallows the use of California NOL deductions if the taxpayer recognizes business income and its adjusted gross income is greater than $ 1,000,000 . The carryover periods for NOL deductions disallowed by this provision will be extended. Additionally, any business credit will only offset a maximum of $ 5,000,000 of California tax. Given the Company’s taxable loss position, this legislation did not impact the tax provision for the years ended December 31, 2020 or 2021. California Senate Bill 113 (SB 113), was signed into law by Governor Newsom on February 9, 2022. The legislation contains important California tax law changes, including reinstatement of business tax credits and net NOL deductions limited by AB 85 mentioned above. The new tax law should be accounted for under ASC 740 in the period of enactment (2022) but is not expected to have a material impact on the Company’s tax provision due to its taxable loss position. A reconciliation of the Company’s effective tax rate to the statutory U.S. federal rate is as follows: December 31, 2021 December 31, December 31, Federal statutory income tax rate 21.0 % 21.0 % 21.0 % State taxes 6.7 4.3 11.0 Foreign tax rate differential ( 7.7 ) ( 7.9 ) ( 12.4 ) Change in valuation allowance ( 78.3 ) ( 17.3 ) ( 30.5 ) Stock-based compensation ( 1.2 ) 6.7 7.7 Research tax credit 2.4 3.8 3.3 Other — — ( 0.1 ) Sale of future royalties 0.1 ( 9.4 ) — Section 162(m) ( 0.8 ) ( 1.2 ) — Intangible valuation 57.8 — — 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, 2021, 2020 and 2019 , 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. 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. The beginning and ending unrecognized tax benefits amounts are as follows (in thousands): December 31, 2021 December 31, December 31, Unrecognized tax benefits at beginning of period $ 4,650 $ 1,838 $ 398 Increases related to current year tax positions 2,079 2,812 1,440 Unrecognized tax benefits at end of period $ 6,729 $ 4,650 $ 1,838 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.

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Preferred Stock	9. Preferred Stock As of December 31, 2021 and 2020 , the Company’s amended and restated certificate of incorporation 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, 2021 , there are no shares of the Company’s preferred stock issued or outstanding.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Common Stock	10. Common Stock As of December 31, 2021 and 2020 , the Company’s amended and restated certificate of incorporation 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, 2021 December 31, Exercise of options outstanding and release of restricted shares 14,887,847 7,257,221 Exercise of common stock warrants outstanding 250,000 399,999 Issuance of common stock under the 2018 Equity Incentive Plan 2,101,369 2,742,183 Issuance of common stock under the 2018 Employee Share Purchase Plan 453,042 460,000 Total 17,692,258 10,859,403

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	$ 2.5 billion in a Fiscal Year 10.0 % The portion of the award that may be earned based on attainment of an operational milestone is inclusive of, and not in addition to, any portion of the award that may be earned based on the attainment of the performance-based requirement. Therefore, to the extent a portion of the award is earned based on the attainment of an operational milestone, the subsequent tranche(s) of the award that is eligible to be earned based on the performance-based requirement will be reduced by the excess, if any, of the number of shares earned over the cumulative earning percentage provided for in the performance-based requirement. The performance-based requirement and operational milestones were not achieved as of December 31, 2021. 2021 LTPIP Modification Accounting In August 2021, the Company granted annual long-term incentive awards, which included time-vested stock options, time-vested RSUs and performance-based stock options (“PSOs”) to employees and nonemployees. As a result of stockholder approval of the 2021 LTPIP in October, a portion of the annual long-term incentive awards, elected by eligible employees to forgo, was exchanged for the options granted under the LTPIP Program. The Company determined the exchange was a modification under ASC 718. Under ASC 718, the exchange of the original award (annual long-term incentive awards granted in August 2021) with the modified award (options granted under the LTPIP Program) represented a change in the original terms and conditions. The modification resulted in additional compensation cost equal to the incremental value between the original and modified awards to be recognized. The Company considered the fair value, vesting conditions and classification of the annual long-term incentive awards granted in August 2021, immediately prior to the modification date, compared to the fair value of the options granted under the LTPIP Program to determine the incremental value. For the annual long-term incentive awards granted in August 2021, the Company continues to record the unrecognized compensation expense over the original vesting period. For the options granted under the LTPIP Program, in accordance with ASC 718-10-55-16, the Company used the Monte Carlo simulation model to estimate the grant date fair value of the options granted under the LTPIP Program that will be earned upon attainment of the stock price goals and to determine the incremental value. The fair value of the options granted under the LTPIP Program was estimated using the following weighted-average assumptions: Year Ended December 31, 2021 Expected volatility 61 % Risk-free interest rate 1.54 % Dividend yield 0 % Simulation term 9.83 As of grant date, the exchange of equity awards under the LTPIP Program resulted in total incremental stock-based compensation costs of $ 336.3 million to be recognized ratably over a weighted-average period of 5.32 years. The weighted-average grant date fair value of the options granted under the LTPIP Program was $ 49.18 . For the year ended December 31, 2021 , the Company recognized $ 14.2 million of incremental stock based compensation cost for the options granted under the LTPIP Program. As of December 31, 2021 , there was $ 321.1 million of unrecognized incremental stock-based compensation expense related to the 7,404,209 options granted under the LTPIP Program, but not yet earned or vested, to be recognized over a weighted-average period of 5.11 years. Stock Options Stock option activity, including stock options and PSOs under the 2021 LTPIP, 2018 Plan and 2015 Plan is summarized as follows: Number Weighted Weighted Aggregate Outstanding at December 31, 2020 6,897,276 $ 24.52 8.07 $ 841,704 Granted 8,947,553 $ 89.41 Exercised ( 463,796 ) $ 16.69 Forfeited or canceled ( 857,116 ) $ 75.95 Outstanding at December 31, 2021 14,523,917 $ 61.68 8.60 $ 335,440 Shares exercisable December 31, 2021 7,001,426 Vested and expected to vest December 31, 2021 14,523,917 353,751 time-vested stock options and 246,963 PSOs from the annual long-term incentive awards were exchanged for the options granted under the LTPIP Program in 2021. The weighted-average grant date fair value of the time-vested stock options granted for 2021, 2020 and 2019 was $ 51.55 , $ 32.44 and $ 34.11 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 The Company estimated the fair value of employee stock options using the Black-Scholes valuation model. The fair value of time-vested employee stock options was estimated using the following weighted-average assumptions: Year Ended 2021 2020 2019 Expected volatility 61 % 66 % 68 % Risk-free interest rate 1.03 % 0.39 % 1.65 % Dividend yield 0 % 0 % 0 % Expected term 6.25 6.00 5.78 The total fair value of employee options vested during the years ended December 31, 2021, 2020 and 2019 was $ 26.9 million, $ 19.7 million and $ 4.6 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for options granted to employees, including the options granted under the LTPIP Program, was $ 44.1 million, $ 20.8 million and $ 5.7 million, respectively. Restricted Shares Restricted share activity, including restricted stock units (“RSUs”), and performance-based restricted stock units (“PSUs”), under the 2018 Plan and 2015 Plan is summarized as follows: Number of Weighted Unvested at December 31, 2020 359,945 $ 59.54 Granted 193,500 $ 93.89 Vested ( 93,218 ) $ 58.93 Canceled ( 96,297 ) $ 79.19 Unvested at December 31, 2021 363,930 $ 72.75 57,614 time-vested RSUs from the annual long-term incentive awards were exchanged for the options granted under the LTPIP Program in 2021. Employee 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 grante d 184,200 RS Us to employees in 2021. The total fair value of RSUs vested during the year ended December 31, 2021, 2020, and 2019 was $ 3.2 million, $ 0.3 million and $ 0.3 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for RSUs was $ 4.4 million, $ 1.9 million, and $ 0.3 million, respectively. Non-Employee Awards The Company granted 33,655 stock options and 9,300 RSUs to non-employees during the year ended December 31, 2021. The Company granted 41,500 and 15,000 stock options to non-employees during the years ended December 31, 2020 and 2019, 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 2021 2020 2019 Expected volatility 60 % 67 % 73 % Risk-free interest rate 0.97 % 0.36 % 1.61 % Dividend yield 0 % 0 % 0 % Expected term 5.69 5.56 6.08 Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for equity awards granted to non-employees was $ 1.2 million, $ 0.7 million and $ 0.1 million, respectively. Performance-Based Awards In December 2019, the Company granted 170,150 performance-based stock options and 128,900 performance-based RSUs (collectively "2019 PSA"). These equity awards will vest 25 % upon the achievement of specific clinical development milestones. The remaining awards will then vest in three equal annual installments after that date. The performance criteria for 2019 PSA was achieved in June 2021. 42,536 of the performance-based stock options and 28,905 of the performance-based restricted stock vested during 2021. The total fair value of the performance-based stock options and RSUs vested during the years ended December 31, 2021 was $ 4.2 m illion. The Company estimated the fair value of the 2019 PSA using the Black-Scholes valuation model. Significant assumptions utilized in estimating the fair value of 2019 PSA include an expected volatility of 72 %, a risk-free rate of 1.67 %, expected dividend yield of 0 %, and expected term of 6.31 years. In February 2021, the Company granted 190,831 performance-based stock options ("2021 Feb PSO"). These stock options will vest 25 % upon the achievement of specific clinical development milestones. The remaining awards will then vest in 36 successive equal monthly installments after the performance criteria is achieved. As of December 31, 2021, the Company believes that the achievement of the requisite performance criteria for the 2021 Feb PSO continues to be probable. The 2021 Feb PSO fair value was $ 77.41 per share. The Company estimated the fair value of the 2021 Feb PSO using the Black-Scholes valuation model. Significant assumptions utilized in estimating the fair value of 2021 Feb PSO include an expected volatility of 66 %, a risk-free rate of 0.66 %, expected dividend yield of 0 %, and expected term of 5.94 years. In August 2021, the Company granted 478,750 performance-based stock options ("2021 Aug PSO"). These stock options will vest upon the achievement of specific clinical development milestones with the percentage of shares earned being dependent on the relative total stockholder return over the performance period. The remaining shares will then vest in 12 successive equal monthly installments after the performance criteria is achieved. As of December 31, 2021 , the requisite performance criteria for the 2021 Aug PSO was not achieved and not probable; no stock-based compensation expense was recognized during the year ended December 31, 2021. The weighted-average estimated fair value per share of the 2021 Aug PSO was $ 41.49 , which was derived from a Monte Carlo simulation model. Significant assumptions utilized in estimating the fair value of 2021 Aug PSO include an expected volatility of 60 %, a risk-free rate of 1.05 %, expected dividend yield of 0 %, and expected term of 6.49 years. Performance-based stock options are recorded as expense beginning when vesting events are determined to be probable. Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for the performance-based equity awards was $ 11.4 million, $ 7.2 million and less than $ 0.1 million, respectively. 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. Each offering period is twelve months long, with two purchase periods. ESPP participants will purchase shares of common stock at a price per share equal to 85 % of the lesser of (1) the fair market value per share of the common stock on the enrollment date or (2) the fair market value of the common stock on the exercise date. The Company issued 6,958 shares under the ESPP during the year ended December 31, 2021 . Stock-based compensation expense recognized during the year ended December 31, 2021 for the ESPP was $ 0.3 million. Stock-Based Compensation Expense Stock-based compensation is classified in the consolidated statements of operations and comprehensive loss as follows (in thousands): Year Ended 2021 2020 2019 Research and development $ 33,237 $ 16,957 $ 3,496 General and administrative 28,148 13,711 2,614 Total stock-based compensation $ 61,385 $ 30,668 $ 6,110 As of December 31, 2021, the Company had $ 434.4 million of unrecognized compensation expense related to unvested share-based awards and ESPP, which is expected to be recognized over a weighted-average period of 4.4 years. 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, 2021 , there were no early exercised stock options subject to the Company’s right of repurchase." id="sjs-B4">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 ("NSOs"), 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 2,044,492 shares in 2021 and there were 2,101,369 shares available for grant under the 2018 Plan as of December 31, 2021. 2021 Long-Term Performance Incentive Plan In August 2021, the Company adopted the 2021 Long-Term Performance Incentive Plan (“2021 LTPIP”), which was approved by the Company's stockholders on October 13, 2021. The 2021 LTPIP was designed to be a long-term, pay-for-performance, incentive plan that would further align the interests of management and other eligible employees with the creation of substantial long-term value for the Company's stockholders. Eligible employees at or above grade level 10 were provided a one-time opportunity to “opt-in” or “buy-in” to the 2021 LTPIP, via a one-time election, and, if they so elected, agreed to forgo up to 75% of their annual equity incentive awards for the next seven years, and instead received a one-time grant of performance-based stock options that could potentially provide three times more value than the forgone annual equity incentive compensation. Additionally, the Company granted stock options to eligible employees below grade level 10 under the broader long-term performance incentive program terms from the existing share reserve under the 2018 Plan and not pursuant to the 2021 LTPIP. The terms for the stock options granted under the 2021 LTPIP and the 2018 Plan are collectively referred to as the "LTPIP Program". The 2021 LTPIP reserved 5,502,334 shares of common stock for the issuance of NSOs. For the year ended December 31, 2021, 5,502,334 performance-based stock options were granted under the 2021 LTPIP. There were no shares available for grant under the 2021 LTPIP as of December 31, 2021. An additional 1,920,625 performance-based stock options were granted under the 2018 Plan as part of the LTPIP Program. The exercise price of options granted under the LTPIP Program was $ 88.21 , the fair market value of the common stock on August 12, 2021, the date of approval by the board of directors. Shares underlying the options granted under the LTPIP Program may be earned based on the achievement of the performance-based requirement and/or certain operational milestones; after being earned, the shares then generally vest based on continued service with the Company following the date earned and through the end of the seven-year performance period. The performance-based requirement consists of seven tranches of stock price goals. The first tranche requires the Company's stock price per share to meet or exceed $ 200 , with each tranche thereafter requiring a $ 100 incremental increase up to $ 800 for the last tranche. A percentage of the shares underlying the option will be earned based on the stock price meeting or exceeding the corresponding stock price goal for a period of 90 consecutive trading days during the seven-year performance period, as follows: Performance-Based Requirement Target Tranche Earning Cumulative Earning Tranche One $ 200 7.5 % 7.5 % Tranche Two $ 300 12.5 % 20.0 % Tranche Three $ 400 25.0 % 45.0 % Tranche Four $ 500 25.0 % 70.0 % Tranche Five $ 600 20.0 % 90.0 % Tranche Six $ 700 5.0 % 95.0 % Tranche Seven $ 800 5.0 % 100.0 % Up to 35 % of the shares underlying an option may also be earned based on the Company’s achievement of certain operational milestones during the seven-year performance period. A participant may earn up to 25 % of their award based on approval by the U.S. Food and Drug Administration of a Biologics License Application in respect of a first, second, and third major indication (RVO, DME and/or wAMD). An additional operational milestone requires the Company to generate sales of at least $ 2.5 billion in a completed fiscal year. The maximum percentage of shares that can be earned based on the attainment of the operational milestones is as follows: Operational Milestone Operational Milestone Earning Percentage First BLA Approval 15.0 % Second BLA Approval 5.0 % Third BLA Approval 5.0 % Sales > $ 2.5 billion in a Fiscal Year 10.0 % The portion of the award that may be earned based on attainment of an operational milestone is inclusive of, and not in addition to, any portion of the award that may be earned based on the attainment of the performance-based requirement. Therefore, to the extent a portion of the award is earned based on the attainment of an operational milestone, the subsequent tranche(s) of the award that is eligible to be earned based on the performance-based requirement will be reduced by the excess, if any, of the number of shares earned over the cumulative earning percentage provided for in the performance-based requirement. The performance-based requirement and operational milestones were not achieved as of December 31, 2021. 2021 LTPIP Modification Accounting In August 2021, the Company granted annual long-term incentive awards, which included time-vested stock options, time-vested RSUs and performance-based stock options (“PSOs”) to employees and nonemployees. As a result of stockholder approval of the 2021 LTPIP in October, a portion of the annual long-term incentive awards, elected by eligible employees to forgo, was exchanged for the options granted under the LTPIP Program. The Company determined the exchange was a modification under ASC 718. Under ASC 718, the exchange of the original award (annual long-term incentive awards granted in August 2021) with the modified award (options granted under the LTPIP Program) represented a change in the original terms and conditions. The modification resulted in additional compensation cost equal to the incremental value between the original and modified awards to be recognized. The Company considered the fair value, vesting conditions and classification of the annual long-term incentive awards granted in August 2021, immediately prior to the modification date, compared to the fair value of the options granted under the LTPIP Program to determine the incremental value. For the annual long-term incentive awards granted in August 2021, the Company continues to record the unrecognized compensation expense over the original vesting period. For the options granted under the LTPIP Program, in accordance with ASC 718-10-55-16, the Company used the Monte Carlo simulation model to estimate the grant date fair value of the options granted under the LTPIP Program that will be earned upon attainment of the stock price goals and to determine the incremental value. The fair value of the options granted under the LTPIP Program was estimated using the following weighted-average assumptions: Year Ended December 31, 2021 Expected volatility 61 % Risk-free interest rate 1.54 % Dividend yield 0 % Simulation term 9.83 As of grant date, the exchange of equity awards under the LTPIP Program resulted in total incremental stock-based compensation costs of $ 336.3 million to be recognized ratably over a weighted-average period of 5.32 years. The weighted-average grant date fair value of the options granted under the LTPIP Program was $ 49.18 . For the year ended December 31, 2021 , the Company recognized $ 14.2 million of incremental stock based compensation cost for the options granted under the LTPIP Program. As of December 31, 2021 , there was $ 321.1 million of unrecognized incremental stock-based compensation expense related to the 7,404,209 options granted under the LTPIP Program, but not yet earned or vested, to be recognized over a weighted-average period of 5.11 years. Stock Options Stock option activity, including stock options and PSOs under the 2021 LTPIP, 2018 Plan and 2015 Plan is summarized as follows: Number Weighted Weighted Aggregate Outstanding at December 31, 2020 6,897,276 $ 24.52 8.07 $ 841,704 Granted 8,947,553 $ 89.41 Exercised ( 463,796 ) $ 16.69 Forfeited or canceled ( 857,116 ) $ 75.95 Outstanding at December 31, 2021 14,523,917 $ 61.68 8.60 $ 335,440 Shares exercisable December 31, 2021 7,001,426 Vested and expected to vest December 31, 2021 14,523,917 353,751 time-vested stock options and 246,963 PSOs from the annual long-term incentive awards were exchanged for the options granted under the LTPIP Program in 2021. The weighted-average grant date fair value of the time-vested stock options granted for 2021, 2020 and 2019 was $ 51.55 , $ 32.44 and $ 34.11 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 The Company estimated the fair value of employee stock options using the Black-Scholes valuation model. The fair value of time-vested employee stock options was estimated using the following weighted-average assumptions: Year Ended 2021 2020 2019 Expected volatility 61 % 66 % 68 % Risk-free interest rate 1.03 % 0.39 % 1.65 % Dividend yield 0 % 0 % 0 % Expected term 6.25 6.00 5.78 The total fair value of employee options vested during the years ended December 31, 2021, 2020 and 2019 was $ 26.9 million, $ 19.7 million and $ 4.6 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for options granted to employees, including the options granted under the LTPIP Program, was $ 44.1 million, $ 20.8 million and $ 5.7 million, respectively. Restricted Shares Restricted share activity, including restricted stock units (“RSUs”), and performance-based restricted stock units (“PSUs”), under the 2018 Plan and 2015 Plan is summarized as follows: Number of Weighted Unvested at December 31, 2020 359,945 $ 59.54 Granted 193,500 $ 93.89 Vested ( 93,218 ) $ 58.93 Canceled ( 96,297 ) $ 79.19 Unvested at December 31, 2021 363,930 $ 72.75 57,614 time-vested RSUs from the annual long-term incentive awards were exchanged for the options granted under the LTPIP Program in 2021. Employee 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 grante d 184,200 RS Us to employees in 2021. The total fair value of RSUs vested during the year ended December 31, 2021, 2020, and 2019 was $ 3.2 million, $ 0.3 million and $ 0.3 million, respectively. Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for RSUs was $ 4.4 million, $ 1.9 million, and $ 0.3 million, respectively. Non-Employee Awards The Company granted 33,655 stock options and 9,300 RSUs to non-employees during the year ended December 31, 2021. The Company granted 41,500 and 15,000 stock options to non-employees during the years ended December 31, 2020 and 2019, 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 2021 2020 2019 Expected volatility 60 % 67 % 73 % Risk-free interest rate 0.97 % 0.36 % 1.61 % Dividend yield 0 % 0 % 0 % Expected term 5.69 5.56 6.08 Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for equity awards granted to non-employees was $ 1.2 million, $ 0.7 million and $ 0.1 million, respectively. Performance-Based Awards In December 2019, the Company granted 170,150 performance-based stock options and 128,900 performance-based RSUs (collectively "2019 PSA"). These equity awards will vest 25 % upon the achievement of specific clinical development milestones. The remaining awards will then vest in three equal annual installments after that date. The performance criteria for 2019 PSA was achieved in June 2021. 42,536 of the performance-based stock options and 28,905 of the performance-based restricted stock vested during 2021. The total fair value of the performance-based stock options and RSUs vested during the years ended December 31, 2021 was $ 4.2 m illion. The Company estimated the fair value of the 2019 PSA using the Black-Scholes valuation model. Significant assumptions utilized in estimating the fair value of 2019 PSA include an expected volatility of 72 %, a risk-free rate of 1.67 %, expected dividend yield of 0 %, and expected term of 6.31 years. In February 2021, the Company granted 190,831 performance-based stock options ("2021 Feb PSO"). These stock options will vest 25 % upon the achievement of specific clinical development milestones. The remaining awards will then vest in 36 successive equal monthly installments after the performance criteria is achieved. As of December 31, 2021, the Company believes that the achievement of the requisite performance criteria for the 2021 Feb PSO continues to be probable. The 2021 Feb PSO fair value was $ 77.41 per share. The Company estimated the fair value of the 2021 Feb PSO using the Black-Scholes valuation model. Significant assumptions utilized in estimating the fair value of 2021 Feb PSO include an expected volatility of 66 %, a risk-free rate of 0.66 %, expected dividend yield of 0 %, and expected term of 5.94 years. In August 2021, the Company granted 478,750 performance-based stock options ("2021 Aug PSO"). These stock options will vest upon the achievement of specific clinical development milestones with the percentage of shares earned being dependent on the relative total stockholder return over the performance period. The remaining shares will then vest in 12 successive equal monthly installments after the performance criteria is achieved. As of December 31, 2021 , the requisite performance criteria for the 2021 Aug PSO was not achieved and not probable; no stock-based compensation expense was recognized during the year ended December 31, 2021. The weighted-average estimated fair value per share of the 2021 Aug PSO was $ 41.49 , which was derived from a Monte Carlo simulation model. Significant assumptions utilized in estimating the fair value of 2021 Aug PSO include an expected volatility of 60 %, a risk-free rate of 1.05 %, expected dividend yield of 0 %, and expected term of 6.49 years. Performance-based stock options are recorded as expense beginning when vesting events are determined to be probable. Stock-based compensation expense recognized during the years ended December 31, 2021, 2020 and 2019 for the performance-based equity awards was $ 11.4 million, $ 7.2 million and less than $ 0.1 million, respectively. 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. Each offering period is twelve months long, with two purchase periods. ESPP participants will purchase shares of common stock at a price per share equal to 85 % of the lesser of (1) the fair market value per share of the common stock on the enrollment date or (2) the fair market value of the common stock on the exercise date. The Company issued 6,958 shares under the ESPP during the year ended December 31, 2021 . Stock-based compensation expense recognized during the year ended December 31, 2021 for the ESPP was $ 0.3 million. Stock-Based Compensation Expense Stock-based compensation is classified in the consolidated statements of operations and comprehensive loss as follows (in thousands): Year Ended 2021 2020 2019 Research and development $ 33,237 $ 16,957 $ 3,496 General and administrative 28,148 13,711 2,614 Total stock-based compensation $ 61,385 $ 30,668 $ 6,110 As of December 31, 2021, the Company had $ 434.4 million of unrecognized compensation expense related to unvested share-based awards and ESPP, which is expected to be recognized over a weighted-average period of 4.4 years. 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, 2021 , there were no early exercised stock options subject to the Company’s right of repurchase.

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2021
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 2021 2020 2019 Numerator: Net loss attributable to common stockholders $ ( 266,990 ) $ ( 133,096 ) $ ( 47,365 ) Denominator: Weighted-average shares outstanding 51,788,918 45,741,845 37,869,291 Less: weighted-average unvested restricted shares — — ( 15,675 ) Weighted-average shares outstanding used in 51,788,918 45,741,845 37,853,616 Net loss per share attributable to common stockholders, $ ( 5.16 ) $ ( 2.91 ) $ ( 1.25 ) 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: As of December 31, 2021 2020 2019 Outstanding stock options 14,523,917 6,897,276 6,671,542 Unvested restricted shares 363,930 359,945 160,747 Total 14,887,847 7,257,221 6,832,289

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [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, 2021, 2020 and 2019, the expense related to the matching contributions was $ 0.7 million, $ 0.6 million and $ 0.3 million, respectively.

Liability Related to Sale of Fu

Liability Related to Sale of Future Royalties	12 Months Ended
	Dec. 31, 2021
Liability Related To Sale Of Future Royalties [Abstract]
Liability related to Sale of Future Royalties	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 capital 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, was payable upon enrollment of 50 % of the patients in the RVO clinical program. In July 2021, the funding agreement was amended, at the Company’s request, that the remaining funding amount of $125.0 million would not be paid. As a result, $0.2 million of deferred financing cost was expensed during the year ended December 31, 2021. 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, 2021, royalty payments are not probable and estimable. For the year ended December 31, 2021 and 2020 , no interest expense was recognized for the liability related to the sale of future royalties.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2021
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 2021 and 2020 (in thousands, except per share data): Three Months Ended March 31, June 30, September 30, December 31, Loss from operations $ ( 50,558 ) $ ( 55,909 ) $ ( 67,535 ) $ ( 93,049 ) Net loss ( 50,447 ) ( 55,852 ) ( 67,526 ) ( 93,165 ) Net loss per share attributable to common $ ( 0.98 ) $ ( 1.08 ) $ ( 1.30 ) $ ( 1.79 ) Three Months Ended March 31, June 30, September 30, December 31, 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 $ ( 0.54 ) $ ( 0.58 ) $ ( 0.80 ) $ ( 0.97 )

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
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, $ 0.3 million, and less than $ 0.1 million for the years ended December 31, 2021, 2020 and 2019 , 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 retinal 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, 2021 and 2020 , cash, cash equivalents and marketable securities were invested primarily in money market funds, U.S. treasury securities 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 may invest 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 can 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, 2021, and 2020, the Company had $ 6.3 million and $ 6.3 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. Construction in progress reflects amounts incurred for construction or improvements of property or equipment that have not been placed in service. 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 am ount 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, 2021 and 2020.
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 or the Monte Carlo simulation model, which requires the input of subjective assumptions, including (i) the calculation of expected term of the award, (ii) the expected stock price volatility, (iii) the risk-free interest rate, and (iv) expected dividends. 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, and equals the midpoint between the vesting date and maximum contractual expiration date. The expected volatility is estimated based on the Company's historical information for its common stock and supplemented by the historical stock price volatility of a representative peer group over a period equivalent to the expected term of the equity award. The risk-free interest rate is estimated based on the U.S. Treasury securities with maturity dates commensurate with the expected term of the equity award. The Company has never paid, and does not expect to pay, dividends in the foreseeable future. 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. Refer to Note 11.
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. In July 2021, the funding agreement was amended, at the Company’s request, that the remaining funding amount of $ 125.0 million would no t be paid. 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. 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 a ccounting p ronouncements 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. There have been no new accounting pronouncements issued nor adopted during the year ended December 31, 2021 that are of significance to the Company.

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment, net	Property and equipment, net consists of the following (in thousands): December 31, December 31, Leasehold improvement $ 1,285 $ 1,285 Laboratory equipment 4,565 3,351 Furniture and fixtures 214 214 Computer hardware 200 31 Computer software 89 89 Office equipment 107 107 Construction in progress 37,809 2,229 Total property and equipment 44,269 7,306 Less: Accumulated depreciation ( 2,939 ) ( 2,170 ) Property and equipment, net $ 41,330 $ 5,136

Accrued Liabilities and Other_2

Accrued Liabilities and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
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, December 31, Accrued clinical trial and related costs $ 21,776 $ 11,119 Accrued leasehold improvements 13,021 19 Accrued salaries and benefits 6,187 5,094 Accrued research and development 6,041 3,082 Accrued legal fees 403 252 Accrued professional fees 176 253 Accrued other liabilities 715 583 Total accrued and other current liabilities $ 48,319 $ 20,402

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 706,703 $ — $ — $ 706,703 Total $ 706,703 $ — $ — $ 706,703 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

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Summary of Marketable Securities Held	The following table summarizes the marketable securities (in thousands): As of December 31, 2020 Amortized Unrealized Unrealized Fair 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

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of Maturities of Operating Lease Liabilities	The maturities of the operating lease liabilities as of December 31, 2021 were as follows (in thousands): Year ending December 31, As of 2022 $ 7,306 2023 14,531 2024 15,023 2025 15,461 2026 15,912 Thereafter 55,486 Total undiscounted lease payments 123,719 Less: imputed interest ( 33,360 ) Less: future tenant improvement reimbursements ( 10,363 ) Total operating lease liabilities $ 79,996
Summary of Lessee, Weighted Average Remaining Lease Term and Weighted Average Discount Rates	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, December 31, Weighted-average remaining lease term (in years) 8.8 9.5 Weighted-average discount rate 6.7 % 6.7 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 Year Ended December 31, Year Ended December 31, Current: Federal $ — $ — $ — State — — — Foreign 74 14 — Total current 74 14 — Deferred: Federal — — — State — — — Foreign — — — Total deferred — — — Provision (Benefit) for income taxes $ 74 $ 14 $ —
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, 2021 December 31, December 31, Deferred tax assets: Net operating loss carryforwards $ 75,259 $ 28,451 $ 18,523 Intangible assets 166,269 12,088 12,112 Research and development tax credits 18,330 10,527 4,037 Stock-based compensation 10,823 8,405 1,539 Accruals 1,532 1,367 885 Operating lease liability 23,142 22,276 577 Property and equipment — 127 143 Total deferred tax assets 295,355 83,241 37,816 Valuation allowance ( 275,788 ) ( 62,005 ) ( 37,249 ) Net deferred tax assets 19,567 21,236 567 Deferred tax liabilities: Operating lease right-of-use asset ( 19,217 ) ( 21,234 ) ( 534 ) Capitalized legal fees — ( 2 ) ( 33 ) Property and equipment ( 350 ) — — Total deferred tax liabilities ( 19,567 ) ( 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, 2021 December 31, December 31, Federal statutory income tax rate 21.0 % 21.0 % 21.0 % State taxes 6.7 4.3 11.0 Foreign tax rate differential ( 7.7 ) ( 7.9 ) ( 12.4 ) Change in valuation allowance ( 78.3 ) ( 17.3 ) ( 30.5 ) Stock-based compensation ( 1.2 ) 6.7 7.7 Research tax credit 2.4 3.8 3.3 Other — — ( 0.1 ) Sale of future royalties 0.1 ( 9.4 ) — Section 162(m) ( 0.8 ) ( 1.2 ) — Intangible valuation 57.8 — — 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, 2021 December 31, December 31, Unrecognized tax benefits at beginning of period $ 4,650 $ 1,838 $ 398 Increases related to current year tax positions 2,079 2,812 1,440 Unrecognized tax benefits at end of period $ 6,729 $ 4,650 $ 1,838

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuances	The Company had reserved common stock for future issuances as follows: December 31, 2021 December 31, Exercise of options outstanding and release of restricted shares 14,887,847 7,257,221 Exercise of common stock warrants outstanding 250,000 399,999 Issuance of common stock under the 2018 Equity Incentive Plan 2,101,369 2,742,183 Issuance of common stock under the 2018 Employee Share Purchase Plan 453,042 460,000 Total 17,692,258 10,859,403

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Performance of the tranche of Common stock issued	A percentage of the shares underlying the option will be earned based on the stock price meeting or exceeding the corresponding stock price goal for a period of 90 consecutive trading days during the seven-year performance period, as follows: Performance-Based Requirement Target Tranche Earning Cumulative Earning Tranche One $ 200 7.5 % 7.5 % Tranche Two $ 300 12.5 % 20.0 % Tranche Three $ 400 25.0 % 45.0 % Tranche Four $ 500 25.0 % 70.0 % Tranche Five $ 600 20.0 % 90.0 % Tranche Six $ 700 5.0 % 95.0 % Tranche Seven $ 800 5.0 % 100.0 %
Schedule of earning percentage of options	The maximum percentage of shares that can be earned based on the attainment of the operational milestones is as follows: Operational Milestone Operational Milestone Earning Percentage First BLA Approval 15.0 % Second BLA Approval 5.0 % Third BLA Approval 5.0 % Sales > $ 2.5 billion in a Fiscal Year 10.0 %
Schedule of fair value of the options as per following weighted-average assumptions	The fair value of the options granted under the LTPIP Program was estimated using the following weighted-average assumptions: Year Ended December 31, 2021 Expected volatility 61 % Risk-free interest rate 1.54 % Dividend yield 0 % Simulation term 9.83
Summary of Stock Options Activity Under 2021 LTPIP, 2018 Plan and 2015 Plan	Stock option activity, including stock options and PSOs under the 2021 LTPIP, 2018 Plan and 2015 Plan is summarized as follows: Number Weighted Weighted Aggregate Outstanding at December 31, 2020 6,897,276 $ 24.52 8.07 $ 841,704 Granted 8,947,553 $ 89.41 Exercised ( 463,796 ) $ 16.69 Forfeited or canceled ( 857,116 ) $ 75.95 Outstanding at December 31, 2021 14,523,917 $ 61.68 8.60 $ 335,440 Shares exercisable December 31, 2021 7,001,426 Vested and expected to vest December 31, 2021 14,523,917
Fair Value of Employee Stock Options Estimated Using Weighted-average Assumptions	The Company estimated the fair value of employee stock options using the Black-Scholes valuation model. The fair value of time-vested employee stock options was estimated using the following weighted-average assumptions: Year Ended 2021 2020 2019 Expected volatility 61 % 66 % 68 % Risk-free interest rate 1.03 % 0.39 % 1.65 % Dividend yield 0 % 0 % 0 % Expected term 6.25 6.00 5.78
Fair Value of Non-Employee Awards Estimated Using Weighted-average Assumptions	The fair value of non-employee stock options was estimated using the following weighted-average assumptions: Year Ended 2021 2020 2019 Expected volatility 60 % 67 % 73 % Risk-free interest rate 0.97 % 0.36 % 1.61 % Dividend yield 0 % 0 % 0 % Expected term 5.69 5.56 6.08
Summary of Restricted Shares	Restricted share activity, including restricted stock units (“RSUs”), and performance-based restricted stock units (“PSUs”), under the 2018 Plan and 2015 Plan is summarized as follows: Number of Weighted Unvested at December 31, 2020 359,945 $ 59.54 Granted 193,500 $ 93.89 Vested ( 93,218 ) $ 58.93 Canceled ( 96,297 ) $ 79.19 Unvested at December 31, 2021 363,930 $ 72.75
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 2021 2020 2019 Research and development $ 33,237 $ 16,957 $ 3,496 General and administrative 28,148 13,711 2,614 Total stock-based compensation $ 61,385 $ 30,668 $ 6,110

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Computation of Basic and Diluted 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 2021 2020 2019 Numerator: Net loss attributable to common stockholders $ ( 266,990 ) $ ( 133,096 ) $ ( 47,365 ) Denominator: Weighted-average shares outstanding 51,788,918 45,741,845 37,869,291 Less: weighted-average unvested restricted shares — — ( 15,675 ) Weighted-average shares outstanding used in 51,788,918 45,741,845 37,853,616 Net loss per share attributable to common stockholders, $ ( 5.16 ) $ ( 2.91 ) $ ( 1.25 )
Summary of Anti-dilutive Securities Excluded from Computation of Diluted Net Loss per Share	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: As of December 31, 2021 2020 2019 Outstanding stock options 14,523,917 6,897,276 6,671,542 Unvested restricted shares 363,930 359,945 160,747 Total 14,887,847 7,257,221 6,832,289

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following table provides the selected quarterly financial information for the years 2021 and 2020 (in thousands, except per share data): Three Months Ended March 31, June 30, September 30, December 31, Loss from operations $ ( 50,558 ) $ ( 55,909 ) $ ( 67,535 ) $ ( 93,049 ) Net loss ( 50,447 ) ( 55,852 ) ( 67,526 ) ( 93,165 ) Net loss per share attributable to common $ ( 0.98 ) $ ( 1.08 ) $ ( 1.30 ) $ ( 1.79 ) Three Months Ended March 31, June 30, September 30, December 31, 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 $ ( 0.54 ) $ ( 0.58 ) $ ( 0.80 ) $ ( 0.97 )

The Company - Additional Inform

The Company - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Nov. 30, 2020	Dec. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net proceeds from issuance of common stock				$ 612,016	$ 297,616
Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period				5,972,222	6,900,000
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	$ 46			$ 46

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	Dec. 01, 2019USD ($)	Dec. 31, 2021USD ($)Segment	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Jul. 31, 2021USD ($)	Feb. 29, 2020USD ($)
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	$ 6,324,000	$ 140,000
Property and equipment estimated useful lives of assets			5 years
Loss on disposal of long-lived asset		0	$ 0
Unrecognized tax benefits, interest and penalties charged		0
Operating lease right-of-use asset		66,744,000	73,672,000
Operating Lease, Liability		79,996,000
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
Funds Payable Upon Enrollment Of Patients		$ 0			$ 125,000,000	$ 125,000,000
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	$ 6,300,000
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 - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant and Equipment [Line Items]
Total property and equipment	$ 44,269	$ 7,306
Less: Accumulated depreciation	(2,939)	(2,170)
Property and equipment, net	41,330	5,136
Leasehold Improvement
Property Plant and Equipment [Line Items]
Total property and equipment	1,285	1,285
Laboratory Equipment
Property Plant and Equipment [Line Items]
Total property and equipment	4,565	3,351
Furniture and Fixtures
Property Plant and Equipment [Line Items]
Total property and equipment	214	214
Computer Hardware
Property Plant and Equipment [Line Items]
Total property and equipment	200	31
Computer Software
Property Plant and Equipment [Line Items]
Total property and equipment	89	89
Office Equipment
Property Plant and Equipment [Line Items]
Total property and equipment	107	107
Construction in Progress
Property Plant and Equipment [Line Items]
Total property and equipment	$ 37,809	$ 2,229

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation	$ 1,003	$ 477	$ 538

Accrued Liabilities and Other_3

Accrued Liabilities and Other Current Liabilities - Schedule of Accrued Liabilities and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accrued clinical trial and related costs	$ 21,776	$ 11,119
Accrued leasehold improvements	13,021	19
Accrued salaries and benefits	6,187	5,094
Accrued research and development	6,041	3,082
Accrued legal fees	403	252
Accrued professional fees	176	253
Accrued other liabilities	715	583
Total accrued and other current liabilities	$ 48,319	$ 20,402

Fair Value Measurements - Summa

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, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	$ 706,703	$ 942,063
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	706,703	917,485
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		10,006
Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		14,572
Quoted Price in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	706,703	917,485
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	$ 706,703	917,485
Significant Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total		24,578
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
Significant Observable Inputs (Level 2) | Corporate Notes
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities		$ 14,572

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
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

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities Held (Details) $ in Thousands	Dec. 31, 2020USD ($)
Marketable Securities [Line Items]
Amortized Cost, current	$ 24,525
Unrealized Gains, current	53
Unrealized Losses, current	0
Fair Value, current	24,578
U.S. Treasury Securities
Marketable Securities [Line Items]
Amortized Cost, current	10,003
Unrealized Gains, current	3
Unrealized Losses, current	0
Fair Value, current	10,006
Corporate Notes
Marketable Securities [Line Items]
Amortized Cost, current	14,522
Unrealized Gains, current	50
Unrealized Losses, current	0
Fair Value, current	$ 14,572

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Availability of marketable securities	$ 0
Marketable securities with unrealized losses		$ 0
Realized gains or losses recognized on sale or maturity of available-for-sale debt securities	0
Impairment charges or recoveries related to marketable securities	$ 0	$ 0
Maximum
Marketable Securities [Line Items]
Marketable securities, contractual maturities		1 year

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) ft² in Millions	1 Months Ended				12 Months Ended
	Aug. 31, 2020	Jun. 30, 2020USD ($)ft²Building	Apr. 30, 2020CHF (SFr)m²	Mar. 31, 2016USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2021CHF (SFr)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Apr. 30, 2021USD ($)	Jul. 01, 2020USD ($)
Commitments And Contingencies Disclosure [Line Items]
Operating lease right-of-use asset					$ 66,744,000		$ 73,672,000
Lease liabilities					79,996,000
Current portion of tenant improvement allowance payable					48,319,000		20,402,000
Other liabilities, non-current portion of tenant Improvement allowance payable					211,000		256,000
Tenant Improvement Allowance Payable
Commitments And Contingencies Disclosure [Line Items]
Other liabilities, non-current portion of tenant Improvement allowance payable					200,000		300
Lonza | Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Cancelable and/ or non-cancelable contractual obligations, total					69,500,000		56,500,000
Unrecorded unconditional purchase obligation, expenses recognized					31,800,000		16,800,000	$ 7,900
Unrecorded unconditional purchase obligation, cancellation fees					0
Manufacturing Agreement | Other Assets [Member]
Commitments And Contingencies Disclosure [Line Items]
Manufacturing Agreement Expense					38,700	SFr 35,000,000
Maximum | Tenant Improvement Allowance Payable
Commitments And Contingencies Disclosure [Line Items]
Current portion of tenant improvement allowance payable					100,000		$ 100,000
Clinical and Commercial Supply of Drug Substance | Manufacturing Agreement | Lonza
Commitments And Contingencies Disclosure [Line Items]
Estimated capital contribution									$ 75,000,000
Contractual obligation under funding agreement									$ 150,000,000
Manufacturing agreement initial term	8 years
Clinical and Commercial Supply of Drug Substance | Maximum | Manufacturing Agreement | Lonza
Commitments And Contingencies Disclosure [Line Items]
Manufacturing agreement term that can be extended	16 years
Leasehold Improvements | California
Commitments And Contingencies Disclosure [Line Items]
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 32,000
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
Commitments And Contingencies Disclosure [Line Items]
Tenant improvement allowance					$ 1,400,000
Tenant Improvement Allowance Agreement | 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

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2021USD ($)
Operating Lease
2022	$ 7,306
2023	14,531
2024	15,023
2025	15,461
2026	15,912
Thereafter	55,486
Total undiscounted lease payments	123,719
Less: imputed interest	(33,360)
Less: future tenant improvement reimbursements	(10,363)
Total operating lease liabilities	$ 79,996

Commitments and Contingencies_3

Commitments and Contingencies - Summary of Lessee, Weighted Average Remaining Lease Term and Weighted Average Discount Rates (Details)	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Weighted-average remaining lease term (in years)	8 years 9 months 18 days	9 years 6 months
Weighted-average discount rate	6.70%	6.70%

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 0
State	0
Foreign	74	$ 14
Total current	74	14
Deferred:
Federal	0
State	0
Foreign	0
Total deferred	0
Provision (Benefit) for income taxes	$ 74	$ 14

Income Taxes - Components of Lo

Income Taxes - Components of Loss before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
United States	$ (46,590)	$ (17,273)	$ 2,633
Foreign	(220,326)	(115,809)	(49,998)
Total loss before income taxes	$ (266,916)	$ (133,082)	$ (47,365)

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 75,259	$ 28,451	$ 18,523
Intangible assets	166,269	12,088	12,112
Research and development tax credits	18,330	10,527	4,037
Stock-based compensation	10,823	8,405	1,539
Accruals	1,532	1,367	885
Operating lease liability	23,142	22,276	577
Property and equipment	0	127	143
Total deferred tax assets	295,355	83,241	37,816
Valuation allowance	(275,788)	(62,005)	(37,249)
Net deferred tax assets	19,567	21,236	567
Deferred tax liabilities:
Operating lease right-of-use asset	(19,217)	(21,234)	(534)
Capitalized legal fees		2	33
Property and equipment	350
Total deferred tax liabilities	(19,567)	(21,236)	(567)
Total net deferred tax assets	$ 0	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Increase in valuation allowance	$ 213,800,000	$ 24,800,000	$ 15,900,000
Research and development credit carryforwards	18,330,000	10,527,000	$ 4,037,000
Interest charged	0
Penalties charged	$ 0
CARES Act Member
Income Taxes [Line Items]
Description of corporate income tax provisions	The CARES Act contains several corporate income tax provisions, including making remaining alternative minimum tax credits immediately refundable; providing a 5-year carryback of NOLs generated in tax years 2018, 2019, and 2020, and removing the 80% taxable income limitation on utilization of those NOLs if carried back to prior tax years or utilized in tax years beginning before 2021; temporarily liberalizing the interest deductibility rules under Section 163(j) of the CARES Act, by raising the adjusted taxable income limitation from 30% to 50% for tax years 2019 and 2020 and giving taxpayers the election of using 2019 adjusted taxable income for purposes of computing 2020 interest deductibility
Federal
Income Taxes [Line Items]
Net operating loss	$ 57,500,000
Net operating loss carryforwards expiration start year	2035
Research and development credit carryforwards	$ 17,900,000
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	$ 39,400,000
State
Income Taxes [Line Items]
Net operating loss	$ 395,400
Net operating loss carryforwards expiration start year	2035
Number of periods open for examination	4 years
California
Income Taxes [Line Items]
Net operating loss deductions	$ 1,000,000
California | Maximum
Income Taxes [Line Items]
Offset tax credit	$ 5,000,000	$ 5,000,000

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Effective Tax Rate to Statutory U.S. Federal Rate (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	21.00%	21.00%	21.00%
State taxes	6.70%	4.30%	11.00%
Foreign tax rate differential	(7.70%)	(7.90%)	(12.40%)
Change in valuation allowance	(78.30%)	(17.30%)	(30.50%)
Stock-based compensation	(1.20%)	6.70%	7.70%
Research tax credit	2.40%	3.80%	3.30%
Other			(0.10%)
Sale of future royalties	0.10%	(9.40%)
Section 162(m)	(0.80%)	(1.20%)
Intangible Valuation	57.80%
Provision for income taxes	0.00%	0.00%	0.00%

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits Amounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Unrecognized tax benefits at beginning of period	$ 4,650	$ 1,838	$ 398
Increases related to prior year tax positions	2,079	2,812	1,440
Unrecognized tax benefits at end of period	$ 6,729	$ 4,650	$ 1,838

Preferred Stock - Additional In

Preferred Stock - Additional Information (Details) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Maximum
Class Of Stock [Line Items]
Preferred stock, shares authorized	10,000,000	10,000,000

Common Stock - Additional Infor

Common Stock - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021Vote$ / sharesshares	Dec. 31, 2020Vote$ / sharesshares
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 Comm

Common Stock - Schedule of Common Stock Reserved for Future Issuances (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Common stock reserved for future issuances	17,692,258	10,859,403
Stock Options Outstanding and Release of Restricted Shares
Class Of Stock [Line Items]
Common stock reserved for future issuances	14,887,847	7,257,221
2018 Equity Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for future issuances	2,101,369	2,742,183
2018 Employee Share Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for future issuances	453,042	460,000
Warrant
Class Of Stock [Line Items]
Common stock reserved for future issuances	250,000	399,999

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details)	Aug. 12, 2021$ / shares	Aug. 31, 2021$ / sharesshares	Feb. 28, 2021shares	Dec. 31, 2019shares	Dec. 31, 2021USD ($)Days$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized | $					$ 61,385,000	$ 30,668,000	$ 6,110,000
Common stock, shares reserved for issuance					17,692,258	10,859,403
Unrecognized stock-based compensation expense | $					$ 434,400,000
Unrecognized stock-based compensation weighted-average period expected for recognition					4 years 4 months 24 days
Expected term					6 years 3 months	6 years	5 years 9 months 10 days
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, weighted-average grant date fair value | $ / shares					$ 51.55	$ 32.44	$ 34.11
Operational Milestone Earning Percentage/Dividend yield					0.00%	0.00%	0.00%
Total fair value of employee options vested | $					$ 26,900,000	$ 19,700,000	$ 4,600,000
Stock-based compensation expense recognized | $					$ 44,100,000	$ 20,800,000	$ 5,700,000
Risk-free interest rate					1.03%	0.39%	1.65%
Expected volatility					61.00%	66.00%	68.00%
Non-employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Operational Milestone Earning Percentage/Dividend yield					0.00%	0.00%	0.00%
Risk-free interest rate					0.97%	0.36%	1.61%
Expected volatility					60.00%	67.00%	73.00%
Expected term					5 years 8 months 8 days	5 years 6 months 21 days	6 years 29 days
Options Granted to Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized | $					$ 1,200,000	$ 700,000	$ 100,000
Restricted Stock Awards (RSAs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units, granted					193,500
Awards vested					93,218
Awards cancelled					96,297
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period					4 years
Total fair value of employee options vested | $					$ 3,200,000	300,000	300,000
Stock-based compensation expense recognized | $					$ 4,400,000	1,900,000	300,000
Stock units, granted					184,200
Performance Based Equity Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Operational Milestone Earning Percentage/Dividend yield			25.00%	25.00%	0.00%
Stock-based compensation expense recognized | $					$ 11,400,000	$ 7,200,000	$ 100,000
Weighted-average grant date fair value | $ / shares					$ 41.49
Risk-free interest rate					1.05%
Expected volatility					60.00%
Expected term					6 years 5 months 26 days
Performance-based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, weighted-average grant date fair value | $ / shares					$ 77.41
Total fair value of employee options vested | $					$ 4,200,000
Stock-based compensation expense recognized | $					$ 0
Stock options, vested					42,536
Stock options, granted		478,750	190,831	170,150
Performance Based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total fair value of employee options vested | $					$ 4,200,000
Stock units, granted				128,900
Awards vested					28,905
2019 PSA
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Operational Milestone Earning Percentage/Dividend yield					0.00%
Risk-free interest rate					1.67%
Expected volatility					72.00%
Expected term					6 years 3 months 21 days
2021 PSO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Operational Milestone Earning Percentage/Dividend yield					0.00%
Risk-free interest rate					0.66%
Expected volatility					66.00%
Expected term					5 years 11 months 8 days
Non-Employee Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, granted					33,655	41,500	41,500
Non-Employee Awards | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units, granted					9,300	15,000	15,000
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares increases annually					2,044,492
Awards vesting period					4 years
Number of shares available for grant					2,101,369
2018 Equity Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
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 exercise price, percentage of estimated fair value of shares on grant date					110.00%
Options, periods granted					5 years
2018 Equity Incentive Plan | Performance-based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, granted					1,920,625
2018 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized | $					$ 300,000
Common stock, shares reserved for issuance					460,000
Issuance of common stock pursuant to employee stock purchase plans, shares					6,958
Common stock at price per share					85.00%
2021 LTPIP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for grant					0
Exercise price | $ / shares	$ 88.21
Increase in price target for earning/vesting of the option | $ / shares					$ 100
Consecutive Trading Days | Days					90
Incremental stock-based compensation | $					$ 336,300,000
Stock units, granted					7,404,209
Weighted-average grant date fair value | $ / shares		$ 49.18
Common stock, shares reserved for issuance					5,502,334
Unrecognized stock-based compensation expense | $					$ 321,100,000
Unrecognized stock-based compensation weighted-average period expected for recognition		5 years 3 months 25 days			5 years 1 month 9 days
Sales Forecasting | $					$ 2,500,000,000
2021 LTPIP | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sale of Stock, Price Per Share | $ / shares					$ 200
2021 LTPIP | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of Operational Achivements in Seven Years					35.00%
Sale of Stock, Price Per Share | $ / shares					$ 800
2021 LTPIP | U.S. Food and Drug Administration Department [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Minimum Qualifying Percentage of Achievement					25.00%
2021 LTPIP | Incentive Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards cancelled					246,963
2021 LTPIP | Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense recognized | $					$ 14,200,000
2021 LTPIP | Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards cancelled					57,614
2021 LTPIP | Performance-based Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, granted					5,502,334
2021 LTPIP | Options Cancelled
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards cancelled					353,751

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Performance of the tranche of Common stock issued (Details)	Dec. 31, 2021$ / shares
Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 200
Tranche Earning Percentage	7.50%
Cumulative Earning Percentage	7.5
Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 300
Tranche Earning Percentage	12.50%
Cumulative Earning Percentage	20
Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 400
Tranche Earning Percentage	25.00%
Cumulative Earning Percentage	45
Tranche Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 500
Tranche Earning Percentage	25.00%
Cumulative Earning Percentage	70
Tranche Five [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 600
Tranche Earning Percentage	20.00%
Cumulative Earning Percentage	90
Tranche Six [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 700
Tranche Earning Percentage	5.00%
Cumulative Earning Percentage	95
Tranche Seven [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target Stock Price	$ 800
Tranche Earning Percentage	5.00%
Cumulative Earning Percentage	100

Stock-based Compensation - Sc_2

Stock-based Compensation - Schedule of earning percentage of options (Details)	Dec. 31, 2021
First B L A Approval [Member]
Operational Milestone Earning Percentage	15.00%
Second B L A Approval [Member]
Operational Milestone Earning Percentage	5.00%
Third B L A Approval [Member]
Operational Milestone Earning Percentage	5.00%
Sales > $2.5 billion in a Fiscal Year [Member]
Operational Milestone Earning Percentage	10.00%

Stock-Based Compensation - Sc_3

Stock-Based Compensation - Schedule of earning percentage of options (Parenthetical) (Details) $ in Billions	12 Months Ended
	Dec. 31, 2021USD ($)
Maximum | Operational Milestone [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Sales goal	$ 2.5

Stock-based Compensation - Sc_4

Stock-based Compensation - Schedule of fair value of the options as per following weighted-average assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Simulation term	6 years 3 months	6 years	5 years 9 months 10 days
LTPIP Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	61.00%
Risk-free interest rate	1.54%
Operational Milestone Earning Percentage/Dividend yield	0.00%
Simulation term	9 years 9 months 29 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Options Activity Under 2021 LTPIP, 2018 Plan and 2015 Plan (Details) - 2021 LTPIP, 2018 Plan and 2015 Equity Incentive Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Number of Options
Beginning balance	6,897,276
Granted	8,947,553
Exercised	(463,796)
Forfeited or canceled	(857,116)
Ending balance	14,523,917	6,897,276
Shares exercisable	7,001,426
Vested and expected to vest	14,523,917
Weighted Average Exercise Price
Beginning balance	$ 24.52
Granted	89.41
Exercised	16.69
Forfeited or canceled	75.95
Ending balance	$ 61.68	$ 24.52
Weighted Average Remaining Contractual Term (in years)
Weighted Average Remaining Contractual Term (in years)	8 years 7 months 6 days	8 years 25 days
Aggregate Intrinsic Value
Beginning balance	$ 335,440	$ 841,704

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value of Employee Stock Options Estimated Using Weighted-average Assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term	6 years 3 months	6 years	5 years 9 months 10 days
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	61.00%	66.00%	68.00%
Risk-free interest rate	1.03%	0.39%	1.65%
Operational Milestone Earning Percentage/Dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Fa_2

Stock-Based Compensation - Fair Value of Non-employee Awards Estimated Using Weighted-average Assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term	6 years 3 months	6 years	5 years 9 months 10 days
Non-employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	60.00%	67.00%	73.00%
Risk-free interest rate	0.97%	0.36%	1.61%
Operational Milestone Earning Percentage/Dividend yield	0.00%	0.00%	0.00%
Expected term	5 years 8 months 8 days	5 years 6 months 21 days	6 years 29 days

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Restricted Shares (Details) - Restricted Stock Awards (RSAs)	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Number of Restricted Shares
Unvested, beginning balance | shares	359,945
Granted | shares	193,500
Vested | shares	(93,218)
Canceled | shares	(96,297)
Unvested, ending balance | shares	363,930
Weighted Average Grant Date Fair Value
Unvested, beginning balance | $ / shares	$ 59.54
Granted | $ / shares	93.89
Vested | $ / shares	58.93
Canceled | $ / shares	79.19
Unvested, ending balance | $ / shares	$ 72.75

Stock-Based Compensation - Fa_3

Stock-Based Compensation - Fair Value of Performance-based Stock Options Estimated Using Weighted-average Assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term	6 years 3 months	6 years	5 years 9 months 10 days

Stock-Based Compensation - Su_3

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 61,385	$ 30,668	$ 6,110
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	33,237	16,957	3,496
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 28,148	$ 13,711	$ 2,614

Net Loss per Share Attributab_3

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, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss	$ (93,165)	$ (67,526)	$ (55,852)	$ (50,447)	$ (46,583)	$ (36,122)	$ (25,999)	$ (24,392)	$ (266,990)	$ (133,096)	$ (47,365)
Denominator:
Weighted-average shares outstanding									51,788,918	45,741,845	37,869,291
Less: weighted-average unvested restricted shares and shares subject to repurchase											15,675
Weighted-average common shares outstanding used in computing net loss per common share, basic and diluted									51,788,918	45,741,845	37,853,616
Net loss per share attributable to common stockholders, basic and diluted	$ (1.79)	$ (1.30)	$ (1.08)	$ (0.98)	$ (0.97)	$ (0.80)	$ (0.58)	$ (0.54)	$ (5.16)	$ (2.91)	$ (1.25)

Net Loss per Share Attributab_4

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, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	14,887,847	7,257,221	6,832,289
Outstanding 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	14,523,917	6,897,276	6,671,542
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	363,930	359,945	160,747

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Plan name	401(k)
Defined Contribution Plan, Plan Name [Extensible List]	Retirement and Savings Plan [Member]
Employer matching contribution, percent of match	100.00%
Expense related to matching contributions	$ 0.7	$ 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 _2

Liability Related to Sale of Future Royalties - Additional Information (Details) - USD ($) $ in Thousands	Feb. 04, 2020	Dec. 01, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 31, 2021	Feb. 29, 2020
Related Party Transaction [Line Items]
Proceeds from sale of future royalties			$ 0	$ 99,643
Liability related to sale of future royalties			99,943	99,890
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
Percentage of repurchase of royalties		100.00%
Proceeds from sale of future royalties	$ 100,000
Funds to be payable upon enrollment of patients			$ 0			$ 125,000	$ 125,000
Percentage of repurchase of royalties							50.00%
Liability related to sale of future royalties				$ 100,000
Baker Bros. Advisors LP | Funding Agreement | Minimum
Related Party Transaction [Line Items]
Ownership percentage		5.00%

Selected Quarterly Financial _3

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, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Loss from operations	$ (93,049)	$ (67,535)	$ (55,909)	$ (50,558)	$ (46,842)	$ (36,663)	$ (26,779)	$ (25,723)	$ (267,051)	$ (136,007)	$ (49,190)
Net loss	$ (93,165)	$ (67,526)	$ (55,852)	$ (50,447)	$ (46,583)	$ (36,122)	$ (25,999)	$ (24,392)	$ (266,990)	$ (133,096)	$ (47,365)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.79)	$ (1.30)	$ (1.08)	$ (0.98)	$ (0.97)	$ (0.80)	$ (0.58)	$ (0.54)	$ (5.16)	$ (2.91)	$ (1.25)