0000950170-22-007389 | 10-Q | XBRL Viewer

Print Document View Excel Document

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2022	Apr. 28, 2022
Cover [Abstract]
Entity Registrant Name	FATE THERAPEUTICS, INC.
Entity Central Index Key	0001434316
Document Type	10-Q
Document Period End Date	Mar. 31, 2022
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Trading Symbol	FATE
Entity Common Stock, Shares Outstanding		96,629,085
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-36076
Entity Tax Identification Number	65-1311552
Entity Address, Address Line One	12278 Scripps Summit Drive
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92131
City Area Code	858
Local Phone Number	875-1800
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 64,741	$ 133,583
Accounts receivable	13,850	8,676
Short-term investments and related maturity receivables	509,031	482,327
Prepaid expenses and other current assets	11,453	8,826
Total current assets	599,075	633,412
Long-term investments	67,942	100,664
Property and equipment, net	97,857	91,529
Operating lease right-of-use assets	69,475	70,720
Restricted cash	15,227	15,227
Collaboration contract assets	8,777	9,870
Other assets	33	33
Total assets	858,386	921,455
Current liabilities:
Accounts payable	11,444	8,612
Accrued expenses	35,110	42,412
CIRM award liability, current portion	3,200	3,200
Deferred revenue, current portion	22,575	21,483
Operating lease liabilities, current portion	5,582	5,577
Total current liabilities	77,911	81,284
Deferred revenue, net of current portion	22,534	27,124
CIRM award liability, net of current portion	800	800
Operating lease liabilities, net of current portion	107,939	109,241
Stock price appreciation milestones	15,809	24,168
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; authorized shares-5,000,000 at March 31, 2022 and December 31, 2021; Class A Convertible Preferred shares issued and outstanding-2,794,549 at March 31, 2022 and December 31, 2021	3	3
Common stock, $0.001 par value; authorized shares-250,000,000 at March 31, 2022 and December 31, 2021; issued and outstanding-96,538,084 at March 31, 2022 and 95,726,962 at December 31, 2021	97	96
Additional paid-in capital	1,470,916	1,448,584
Accumulated other comprehensive loss	(2,850)	(762)
Accumulated deficit	(834,773)	(769,083)
Total stockholders’ equity	633,393	678,838
Total liabilities and stockholders’ equity	$ 858,386	$ 921,455

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized shares	250,000,000	250,000,000
Common stock issued	96,538,084	95,726,962
Common stock, outstanding shares	96,538,084	95,726,962
Class A Convertible Preferred Shares
Preferred stock, issued shares	2,794,549	2,794,549
Preferred stock, outstanding shares	2,794,549	2,794,549

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Collaboration revenue	$ 18,414	$ 11,142
Type of Revenue [Extensible List]	us-gaap:LicenseMember	us-gaap:LicenseMember
Operating expenses:
Research and development	$ 72,139	$ 44,852
General and administrative	20,742	12,500
Total operating expenses	92,881	57,352
Loss from operations	(74,467)	(46,210)
Other income:
Interest income	418	377
Change in fair value of stock price appreciation milestones	8,359	744
Total other income	8,777	1,121
Net loss	(65,690)	(45,089)
Other comprehensive loss:
Unrealized loss on available-for-sale securities, net	(2,088)	(330)
Comprehensive loss	$ (67,778)	$ (45,419)
Net loss per common share, basic and diluted	$ (0.68)	$ (0.48)
Weighted-average common shares used to compute basic and diluted net loss per share	96,343,529	93,431,877

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities
Net loss	$ (65,690)	$ (45,089)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,761	959
Stock-based compensation	19,331	12,976
Accretion and amortization of premiums and discounts on investments, net	873	1,140
Amortization of collaboration contract assets	1,094	623
Deferred revenue	(3,497)	(3,107)
Change in fair value of stock price appreciation milestones	8,359	744
Changes in operating assets and liabilities:
Accounts receivable	(5,174)	(1,430)
Prepaid expenses and other assets	(2,407)	(1,301)
Accounts payable and accrued expenses	(3,493)	6,944
Right-of-use assets and lease liabilities, net	(52)	1,933
Net cash used in operating activities	(64,613)	(27,096)
Investing activities
Purchases of property and equipment	(10,084)	(3,981)
Purchases of investments	(132,166)	(529,907)
Maturities of investments	135,224	62,000
Net cash used in investing activities	(7,026)	(471,888)
Financing activities
Issuance of common stock from equity incentive plans, net of issuance costs	2,797	5,605
Proceeds from public offering of common stock and issuance of pre-funded warrants, net of issuance costs		432,445
Net cash provided by financing activities	2,797	438,050
Net change in cash, cash equivalents and restricted cash	(68,842)	(60,934)
Cash, cash equivalents and restricted cash at beginning of the period	148,810	182,574
Cash, cash equivalents and restricted cash at end of the period	79,968	121,640
Supplemental schedule of noncash investing and financing activities
Purchases of property and equipment in accounts payable	3,377	2,624
Right-of use assets obtained in exchange for lease obligations		$ 1,444

Organization and Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Summary of Significant Accounting Policies

1. Organization and Summary of Significant Accounting Policies

Organization

Fate Therapeutics, Inc. (the Company) was incorporated in the state of Delaware on April 27, 2007 and has its principal operations in San Diego, California. The Company is a clinical-stage biopharmaceutical company dedicated to the development of programmed cellular immunotherapies for patients with cancer, including off-the-shelf natural killer (NK) and T-cell product candidates derived from clonal master engineered induced pluripotent stem cell (iPSC) lines.

As of March 31, 2022, the Company has devoted substantially all of its efforts to product development, raising capital and building infrastructure and has not generated any revenues from any sales of its therapeutic products. To date, the Company’s revenues have been derived from collaboration agreements and government grants.

Public Equity Offerings

In January 2021, the Company completed a public offering of common stock in which investors, certain of which are affiliated with a director of the Company, purchased 5.1 million shares of the Company’s common stock at a price of $85.50 per share under a shelf registration statement. In addition, the Company issued pre-funded warrants, in lieu of common stock to certain investors, to purchase 257,310 shares of the Company’s common stock (Pre-Funded Warrants). The purchase price of the Pre-Funded Warrants was $85.499 per Pre-Funded Warrant, which equals the per share public offering price for the shares of common stock less the $0.001 exercise price for each such Pre-Funded Warrant. See Note 8 for additional detail. Gross proceeds from the public offering and the issuance of the Pre-Funded Warrants were $460.0 million, and after giving effect to $27.6 million of costs related to the public offering and the issuance of Pre-Funded Warrants, net proceeds were $432.4 million.

Use of Estimates

The Company’s unaudited condensed consolidated financial statements are prepared in accordance with United States generally accepted accounting principles (U.S. GAAP). The preparation of the Company’s unaudited condensed consolidated financial statements requires management to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s unaudited condensed consolidated financial statements and accompanying notes. The most significant estimates and assumptions in the Company’s unaudited condensed consolidated financial statements relate to its stock price appreciation milestone obligations, contracts containing leases, accrued expenses, stock-based compensation, and the estimated total costs expected to be incurred under the Company’s collaboration agreements. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.

Risks and Uncertainties

Due to the global outbreak of SARS-CoV-2, the strain of coronavirus that causes Coronavirus disease 2019 (COVID-19), the Company continued to experience impacts on certain aspects of its business, including its clinical trial, manufacturing, and research and development activities, during the three months ended March 31, 2022. For example, with the lifting of governmental stay-at-home orders, we have reopened each of our business locations for work onsite, but have also implemented flexible work arrangements in the interests of maintaining the health and safety of our employees. In addition, the COVID-19 pandemic has impacted the timing of our ongoing clinical studies, with slower site activation, patient enrollment and treatment in our clinical studies as a result of precautionary measures taken by some clinical trial sites to protect both site staff and patients from possible COVID-19 exposure. We have also experienced delays in obtaining equipment, materials, and supplies needed to maintain our operations and manufacture our product candidates as a result of production shortages experienced by our suppliers as a result of the COVID-19 pandemic. The scope and duration of these delays and disruptions, and the ultimate impacts of the ongoing COVID-19 pandemic on the Company’s operations, are currently unknown, and depend on continuously changing circumstances, including the emergence of new variants of the virus, such as the Delta and Omicron BA.1 and BA.2 variants. While certain measures have been relaxed in certain parts of the world as increasing numbers of people have received COVID-19 vaccines, others have remained in place with some areas continuing to experience renewed outbreaks and surges in infection rates. The extent to which such measures are removed or new measures are put in place will depend upon how the pandemic evolves, as well as the distribution of available vaccines, the rates at which they are administered and the emergence of new variants of the virus. The Company is continuing to actively monitor the situation and may take further precautionary and preemptive actions as may be required by federal, state or local authorities or that it determines are in

the best interests of public health and safety and that of the Company’s patient community, employees, partners, and stockholders. The Company cannot predict the effects that such actions, or the impact of the ongoing COVID-19 pandemic on global business operations and economic conditions, may have on its business, strategy, collaborations, or financial and operating results.

Principles of Consolidation

The unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries, Fate Therapeutics Ltd., incorporated in the United Kingdom, Fate Therapeutics, B.V., incorporated in the Netherlands and Tfinity Therapeutics, Inc., incorporated in the United States. To date, the aggregate operations of these subsidiaries have not been significant and all intercompany transactions and balances have been eliminated in consolidation.

Cash, Cash Equivalents and Restricted Cash

Cash and cash equivalents include cash in readily available checking and savings accounts, money market accounts and money market funds. The Company considers all highly liquid investments with an original maturity of three months or less from the date of purchase to be cash equivalents.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the unaudited condensed consolidated balance sheets that sum to the total of the same such amount shown in the unaudited condensed consolidated statements of cash flows as of March 31, 2022 and 2021 (in thousands):


	Three Months Ended March 31,
	2022		2021
Cash and cash equivalents	$	64,741	$	106,413
Restricted cash		15,227		15,227
Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statement of cash flows	$	79,968	$	121,640

For each of the three months ended March 31, 2022 and 2021, the restricted cash balance includes cash-collateralized irrevocable standby letters of credit of $15.2 million associated with the Company’s facilities leases.

Investments

Investments are accounted for as available-for-sale securities and are carried at fair value on the unaudited condensed consolidated balance sheets. Upon initial recognition of the investment and at each reporting period, the Company evaluates whether any unrealized losses on investments are attributable to a credit loss or other factors. Any unrealized losses attributable to credit loss are recorded through an allowance for credit losses, limited to the amount by which the fair value is below amortized cost, with the offsetting amount recorded in other income or expense in the unaudited condensed consolidated statement of operations and comprehensive loss. Unrealized losses not attributable to an expected credit loss and unrealized gains on investments are recorded in other comprehensive income (loss) on the unaudited condensed consolidated statements of operations and comprehensive loss. Realized gains and losses, if any, on investments classified as available-for-sale securities are included in other income or expense.

The amortized cost of investments classified as available-for-sale debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income.

Unaudited Interim Financial Information

The accompanying interim condensed consolidated financial statements are unaudited. These unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. GAAP and following the requirements of the United States Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required can be condensed or omitted. The interim unaudited condensed consolidated financial statements should be read in conjunction with the Company’s financial statements and accompanying notes for the fiscal year ended December 31, 2021, contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 filed by the Company with the SEC on February 28, 2022. In management’s opinion, the unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position and its results of operations and comprehensive loss and its cash flows for the periods presented. The results for the three months ended March 31, 2022 are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period.

Revenue Recognition

The Company recognizes revenue in a manner that depicts the transfer of control of a product or a service to a customer and reflects the amount of the consideration the Company is entitled to receive in exchange for such product or service. In doing so, the Company follows a five-step approach: (i) identify the contract with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations, and (v) recognize revenue when (or as) the customer obtains control of the product or service. The Company considers the terms of a contract and all relevant facts and circumstances when applying the revenue recognition standard. The Company applies the revenue recognition standard, including the use of any practical expedients, consistently to contracts with similar characteristics and in similar circumstances.

A customer is a party that has entered into a contract with the Company, where the purpose of the contract is to obtain a product or a service that is an output of the Company’s ordinary activities in exchange for consideration. To be considered a contract, (i) the contract must be approved (in writing, orally, or in accordance with other customary business practices), (ii) each party’s rights regarding the product or the service to be transferred can be identified, (iii) the payment terms for the product or the service to be transferred can be identified, (iv) the contract must have commercial substance (that is, the risk, timing or amount of future cash flows is expected to change as a result of the contract), and (v) it is probable that the Company will collect substantially all of the consideration to which it is entitled to receive in exchange for the transfer of the product or the service.

A performance obligation is defined as a promise to transfer a product or a service to a customer. The Company identifies each promise to transfer a product or a service (or a bundle of products or services, or a series of products and services that are substantially the same and have the same pattern of transfer) that is distinct. A product or a service is distinct if both (i) the customer can benefit from the product or the service either on its own or together with other resources that are readily available to the customer and (ii) the Company’s promise to transfer the product or the service to the customer is separately identifiable from other promises in the contract. Each distinct promise to transfer a product or a service is a unit of accounting for revenue recognition. If a promise to transfer a product or a service is not separately identifiable from other promises in the contract, such promises should be combined into a single performance obligation.

The transaction price is the amount of consideration the Company is entitled to receive in exchange for the transfer of control of a product or a service to a customer. To determine the transaction price, the Company considers the existence of any significant financing component, the effects of any variable elements, noncash considerations and consideration payable to the customer. If a significant financing component exists, the transaction price is adjusted for the time value of money. If an element of variability exists, the Company must estimate the consideration it expects to receive and uses that amount as the basis for recognizing revenue as the product or the service is transferred to the customer. There are two methods for determining the amount of variable consideration: (i) the expected value method, which is the sum of probability-weighted amounts in a range of possible consideration amounts, and (ii) the mostly likely amount method, which identifies the single most likely amount in a range of possible consideration amounts.

If a contract has multiple performance obligations, the Company allocates the transaction price to each distinct performance obligation in an amount that reflects the consideration the Company is entitled to receive in exchange for satisfying each distinct performance obligation. For each distinct performance obligation, revenue is recognized when (or as) the Company transfers control of the product or the service applicable to such performance obligation.

In those instances where the Company first receives consideration in advance of satisfying its performance obligation, the Company classifies such consideration as deferred revenue until (or as) the Company satisfies such performance obligation. In those instances where the Company first satisfies its performance obligation prior to its receipt of consideration, the consideration is recorded as accounts receivable.

The Company expenses incremental costs of obtaining and fulfilling a contract as and when incurred if the expected amortization period of the asset that would be recognized is one year or less, or if the amount of the asset is immaterial. Otherwise, such costs are capitalized as contract assets if they are incremental to the contract and amortized to expense proportionate to revenue recognition of the underlying contract.

Stock Price Appreciation Milestones

The Company estimates the fair value of the stock price appreciation milestones associated with the Amended and Restated Exclusive License Agreement with Memorial Sloan Kettering Cancer Center (see Note 2), using a Monte Carlo simulation model, which relies on the Company’s current stock price as well as significant estimates and assumptions to determine the estimated liability associated with the contingent milestone payments. The Company accounts for the fair value of the stock price appreciation milestones in accordance with Accounting Standards Codification (ASC) 815, Derivatives and Hedging, with fair value marked-to-market at each reporting date. The assumptions used to calculate the fair value of the stock price appreciation milestones are subject to a significant amount of judgment including the probability of achieving a specified clinical milestone, the expected volatility of the Company’s common stock, the risk-free interest rate, and the estimated term, which is based in part on the last valid patent claim date. The Company remeasures the fair value of the stock price appreciation milestones at each balance sheet date, with changes in fair value recorded in earnings as non-operating income or expense on the unaudited condensed consolidated statements of operations and comprehensive loss.

Leases

The Company determines if a contract contains a lease at the inception of the contract. The Company currently has leases related to its facilities leased for office and laboratory space, which are classified as operating leases. These leases result in operating right-of-use (ROU) assets, current operating lease liabilities, and non-current operating lease liabilities in the unaudited condensed consolidated balance sheets. The Company does not have any financing leases. Leases with a term of 12 months or less are considered short-term and ROU assets and lease obligations are not recognized. Payments associated with short-term leases are expensed on a straight-line basis over the lease term.

Lease liabilities represent an obligation to make lease payments arising from the lease and ROU assets represent the right to use the underlying asset identified in the lease for the lease term. Lease liabilities are measured at the present value of the lease payments not yet paid discounted using the discount rate for the lease established at the lease commencement date. To determine the present value, the implicit rate is used when readily determinable. For those leases where the implicit rate is not provided, the Company determines an incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. ROU assets are measured as the present value of the lease payments and also include any prepaid lease payments made and any other indirect costs incurred, and exclude any lease incentives received. Lease terms may include the impact of options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating leases is recognized on a straight-line basis over the lease term. The Company aggregates all lease and non-lease components for each class of underlying assets into a single lease component.

Stock-Based Compensation

Stock-based compensation expense represents the cost of the grant date fair value of employee stock option and restricted stock unit grants recognized over the requisite service period of the awards (usually the vesting period) on a straight-line basis. Performance-based stock units/awards represent a right to receive a certain number of shares of common stock based on the achievement of corporate performance goals and continued employment during the vesting period. At each reporting period, and to the extent achievement of one or any of the performance conditions is probable, the Company reassesses the probability of the achievement of such corporate performance goals and any increase or decrease in share-based compensation expense resulting from an adjustment in the estimated shares to be released is treated as a cumulative catch-up in the period of adjustment. For stock awards for which vesting is subject to both performance-based milestones and market conditions, expense is recorded over the derived service period after the point when the achievement of the performance-based milestone is probable or the performance condition has been achieved.

The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model, with the exception of option grants for which vesting is subject to both performance-based milestones and market conditions, which are valued using a lattice-based model. The fair value of restricted stock units, including performance-based restricted stock units, is based on the closing price of the Company’s common stock as reported on The Nasdaq Global Market on the date of grant. The Company recognizes forfeitures for all awards as such forfeitures occur.

Convertible Preferred Stock

The Company applies the relevant accounting standards to distinguish liabilities from equity when assessing the classification and measurement of preferred stock. Preferred shares subject to mandatory redemptions are considered liabilities and measured at fair value. Conditionally redeemable preferred shares are considered temporary equity. All other preferred shares are considered as stockholders’ equity.

The Company applies the relevant accounting standards for derivatives and hedging (in addition to distinguishing liabilities from equity) when accounting for hybrid contracts that contain conversion options. Conversion options must be bifurcated from the host instruments and accounted for as free-standing financial instruments according to certain criteria. These criteria include circumstances when (i) the economic characteristics and risks of the embedded derivative instruments are not clearly and closely related to the economic characteristics and risks of the host contract, (ii) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured at fair value under otherwise applicable accounting principles with changes in fair value reported in earnings as they occurred, and (iii) a separate instrument with the same terms as the embedded derivative instrument would be considered a derivative instrument. The derivative is subsequently measured at fair value at each reporting date, with the changes in fair value reported in earnings.

Comprehensive Loss

Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non‑owner sources. Other comprehensive loss includes unrealized gains and losses, other than losses attributable to a credit loss which are included in other income and expense, on investments classified as available-for-sale securities, which was the only difference between net loss and comprehensive loss for the applicable periods.

Net Loss per Common Share

Basic net loss per common share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for common stock equivalents. The Pre-Funded Warrants associated with the January 2021 public equity offering (see Note 8) are considered outstanding shares in the basic earnings per share calculation given their nominal exercise price. Dilutive common stock equivalents for the periods presented include convertible preferred stock, warrants for the purchase of common stock, and common stock options and restricted stock units outstanding under the Company’s stock option and incentive plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.

For the three months ended March 31, 2022, the Company realized a net loss of $65.7 million. Shares of potentially dilutive securities totaled 27.7 million for the three months ended March 31, 2022, including 14.0 million shares associated with a hypothetical conversion of all outstanding shares of the Company’s Class A convertible preferred stock, and an aggregate of 13.7 million shares of common stock issuable upon the exercise of outstanding stock options and the vesting of outstanding restricted stock units.

For the three months ended March 31, 2021, the Company realized a net loss of $45.1 million. Shares of potentially dilutive securities totaled 25.5 million for the three months ended March 31, 2021, including 14.0 million shares associated with a hypothetical conversion of all outstanding shares of the Company’s Class A convertible preferred stock, and an aggregate of 11.6 million shares of common stock issuable upon the exercise of outstanding stock options and the vesting of outstanding restricted stock units.

Going Concern Assessment

Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year from the financial statement issuance date. The Company determined that there are no conditions or events that raise substantial doubt about its ability to continue as a going concern for a period of at least twelve months from the date of issuance of these financial statements.

Collaboration and License Agreements

3 Months Ended

Mar. 31, 2022

Collaboration And License Agreements Disclosure [Abstract]

Collaboration and License Agreements

2. Collaboration and License Agreements

Janssen Collaboration and Option Agreement

On April 2, 2020 (the Janssen Agreement Effective Date), the Company entered into a Collaboration and Option Agreement (the Janssen Agreement) with Janssen Biotech, Inc. (Janssen), part of the Janssen Pharmaceutical Companies of Johnson & Johnson. Additionally, on the Janssen Agreement Effective Date, the Company entered into a Stock Purchase Agreement (the Stock Purchase Agreement) with Johnson & Johnson Innovation – JJDC, Inc. (JJDC).

Upon entering the Janssen Agreement, the Company received an upfront, non-refundable and non-creditable payment of $50.0 million. Under the Janssen Agreement, Janssen and the Company will collaborate to develop iPSC-derived CAR NK- and CAR T-cell

product candidates for the treatment of cancer. Janssen will contribute proprietary antigen binding domains directed to up to four tumor-associated antigen targets (the Janssen Cancer Targets). The Company will research and construct iPSC-derived CAR NK- and CAR T-cell product candidates directed to each of the Janssen Cancer Targets (the Collaboration Candidates) and perform preclinical development of Collaboration Candidates. Upon the Company’s completion of activities sufficient to allow the filing of an Investigational New Drug (IND) application for a Collaboration Candidate, Janssen will have the right to exercise an exclusive option and obtain an exclusive license to the Company’s intellectual property rights for the development and commercialization of such Collaboration Candidate. Upon the exercise of such exclusive option, Janssen will be solely responsible for the worldwide clinical development and commercialization of such Collaboration Candidate, and the Company will be primarily responsible for the manufacture, at Janssen’s cost, of such Collaboration Candidate. For each Collaboration Candidate, upon attaining clinical proof-of-concept, the Company shall have the right to elect to co-commercialize and share equally in the profits and losses in the United States, subject to the Company sharing in certain development costs.

Under the Stock Purchase Agreement, the Company sold 1.6 million shares of common stock to JJDC at $31.00 per share, for an aggregate purchase price of approximately $50.0 million, on April 7, 2020. The Company determined that this common stock purchase represented a premium of $9.93 per share, or $16.0 million in aggregate (the Equity Premium), and the remaining $34.0 million was recorded as an issuance of common stock in shareholders’ equity.

In addition, under the Stock Purchase Agreement, the Company had the right to require that JJDC purchase an aggregate of $50.0 million in shares of the Company’s common stock in a private placement at the same price per share as that paid by investors in a public offering. In June 2020, in connection with the Company’s June 2020 public offering, the Company exercised this right and JJDC purchased in a private placement 1.8 million shares of the Company’s common stock at a price of $28.31 per share, for aggregate proceeds of $50.0 million.

Under the terms of the Janssen Agreement, the Company is entitled to receive full funding for all research, preclinical development and IND-enabling activities performed by the Company for Collaboration Candidates, and is eligible to receive (i) with respect to the first Janssen Cancer Target, payments of up to $898.0 million upon the achievement of specified development, regulatory and sales milestones (the Janssen Milestone Payments) for the first Collaboration Candidate, and up to $460.0 million in Janssen Milestone Payments for each additional Collaboration Candidate, directed to the first Janssen Cancer Target; and (ii) with respect to each of the second, third and fourth Janssen Cancer Targets, up to $706.0 million in Janssen Milestone Payments for each of the first Collaboration Candidates, and up to $340.0 million in Janssen Milestone Payments for each additional Collaboration Candidate, directed to the applicable Janssen Cancer Target, where certain Janssen Milestone Payments under (i) and (ii) are subject to reduction in the event the Company elects to co-commercialize and share equally in the profits and losses in the United States of a respective Collaboration Candidate. The Company is further eligible to receive double-digit tiered royalties ranging up to the mid-teens on net sales of Collaboration Candidates that are commercialized by Janssen under the Janssen Agreement, subject to reduction under certain circumstances.

Janssen may terminate the Janssen Agreement with respect to one or more Janssen Cancer Targets, or in its entirety, at any time on or after the second anniversary of the Janssen Agreement Effective Date, and the Company may terminate the Janssen Agreement with respect to a particular Janssen Cancer Target if a Collaboration Candidate has not been selected for IND-enabling studies for such Janssen Cancer Target within specified time periods under certain conditions. The Janssen Agreement contains customary provisions for termination by either party in the event of a material breach of the Janssen Agreement, subject to cure, by the other party and in the event of any bankruptcy, insolvency or similar events with respect to the other party.

The Company applied ASC Topic 808, Collaborative Arrangements (ASC 808) and determined the Janssen Agreement is applicable to such guidance. The Company concluded that Janssen represented a customer and applied relevant guidance from ASC Topic 606, Revenue from Contracts with Customers (ASC 606) to evaluate the appropriate accounting for the Janssen Agreement. In accordance with this guidance, the Company identified its potential performance obligations, including its grant of a license to Janssen to certain of its intellectual property subject to certain conditions, its conduct of research and development services, and its participation in various joint oversight committees. The Company determined that its grant of a license to Janssen to certain of its intellectual property subject to certain conditions was not distinct from other performance obligations because such grant is dependent on the conduct and results of the research and development services. Accordingly, the Company determined that its grant of a license to Janssen and its conduct of research and development services should be accounted for as one combined performance obligation, and that the combined performance obligation is transferred over the expected term of the conduct of the research and development services, which is estimated to be four years. Additionally, the Company determined that participation in the various joint oversight committees did not constitute a performance obligation as the Company’s participation in the various joint oversight committees does not transfer a service.

The Company also assessed the effects of any variable elements under the Janssen Agreement. Such assessment evaluated, among other things, the funding to be received by the Company for its conduct of research and development services. Based on its assessment, the Company concluded that the total amount to be received by the Company for its conduct of research and development services is variable and cannot be readily estimated and, therefore, no amounts associated with such services were included in the initial transaction price. In addition, the Company also assessed its likelihood of receiving (i) preclinical milestones, (ii) various clinical, regulatory and commercial milestone payments, and (iii) royalties on net sales of the Collaboration Candidates. Based on the

likelihood of receiving such milestone payments and royalties, no amounts associated with milestones or royalties were included in the initial transaction price.

In accordance with ASC 606, the Company determined that the initial transaction price under the Janssen Agreement equals $66.0 million, consisting of the upfront, non-refundable and non-creditable payment of $50.0 million and the Equity Premium of $16.0 million. The Company concluded that there was not a significant financing component under the Janssen Agreement. The upfront payment of $66.0 million was recorded as deferred revenue and is being recognized as revenue consistent with the Company’s efforts related to the conduct of research and development services, as the research and development services are the primary component of the combined performance obligation. Since the total amount to be received by the Company for its research and development services under the Janssen Agreement could not be readily estimated, revenue associated with the upfront payment will be recognized based on actual headcount utilized as a percentage of total headcount expected to be utilized over the expected term of the conduct of the research and development services. Revenue associated with the research and development services will be recognized in an amount equal to the actual costs incurred during the period in which the research and development services are performed by the Company.

During the three months ended March 31, 2022, the Company achieved a second research milestone under the Janssen Agreement and recorded a $3.0 million receivable. In accordance with ASC 606, the Company determined that the $3.0 million milestone receivable represented an increase in the initial transaction price under the Janssen Agreement in the form of the receipt of variable consideration that was previously constrained. The Company recognized revenue associated with the $3.0 million milestone receivable in an amount equal to the proportional percentage of actual headcount incurred under the Janssen Agreement since its inception as a percentage of the total headcount expected to be utilized over the expected term of conduct of research and development services under the Janssen Agreement. The remaining unrecognized revenue associated with the $3.0 million milestone was recorded to deferred revenue, and is being recognized as revenue over the expected term of conduct of research and development services.

In connection with the Janssen Agreement, the Company has incurred $14.0 million in sublicense fees to certain of its existing licensors as of March 31, 2022. The $14.0 million in sublicense consideration represents an asset under ASC Topic 340, Other Assets and Deferred Costs (ASC 340) and is amortized to research and development expense ratably with the Company’s revenue recognition under the Janssen Agreement. During the three months ended March 31, 2022 and 2021, the Company recognized $1.1 million and $0.4 million of such expense, respectively. As of March 31, 2022, the Janssen Agreement contract asset balance was $8.8 million.

The Company recognized revenue of $15.9 million under the Janssen Agreement for the three months ended March 31, 2022. Such revenue comprised $9.8 million associated with research and development services and $6.1 million associated with the upfront fee and Equity Premium for the three months ended March 31, 2022. The Company recognized revenue of $8.6 million for the three months ended March 31, 2021. Such revenue comprised $6.8 million associated with research and development services and $1.8 million associated with the upfront fee and Equity Premium for the three months ended March 31, 2021. As of March 31, 2022, aggregate deferred revenue related to the Janssen Agreement was $45.1 million, of which $22.6 million is classified as current.

As of March 31, 2022, the Company has received $39.9 million in aggregate research and development fees from Janssen.

Ono Collaboration and Option Agreement

On September 14, 2018 (the Ono Agreement Effective Date), the Company entered into a Collaboration and Option Agreement (the Ono Agreement) with Ono Pharmaceutical Co. Ltd. (Ono) for the joint development and commercialization of two off-the-shelf iPSC-derived chimeric antigen receptor (CAR) T-cell product candidates. The first off-the-shelf, iPSC-derived CAR T-cell candidate (Candidate 1) targets an antigen expressed on certain lymphoblastic leukemias, and the second off-the-shelf, iPSC-derived CAR T-cell candidate (Candidate 2) targets a novel antigen identified by Ono expressed on certain solid tumors (each a Candidate and collectively the Candidates).

On December 4, 2020, the Company and Ono entered into a letter agreement (the Ono Letter Agreement) in connection with the Ono Agreement. Pursuant to the Ono Letter Agreement, Ono delivered to the Company proprietary antigen binding domains targeting an antigen expressed on certain solid tumors and nominated such antigen binding domains as the Ono Antigen Binding Domain for incorporation into Candidate 2. In connection with such nomination and pursuant to the original agreement, in December 2020, Ono paid the Company a milestone fee of $10.0 million for further research and development of Candidate 2 and Ono maintains its option to this candidate. In addition, in connection with the Ono Letter Agreement, the Company and Ono agreed to the termination of the Ono Agreement with respect to Candidate 1. The Company retains all rights, in its sole discretion, to research, develop and commercialize Candidate 1 throughout the world without any obligation to Ono.

Pursuant to the Ono Agreement, the Company and Ono are jointly conducting research and development activities under a joint development plan, with the goal of advancing Candidate 2 to a pre-defined preclinical milestone. The Company has granted to Ono, during a specified period of time, an option to obtain an exclusive license under certain intellectual property rights to develop and commercialize Candidate 2 in all territories of the world, with the Company retaining the right to co-develop and co-commercialize Candidate 2 in the United States and Europe under a joint arrangement whereby it is eligible to share at least 50% of the profits and losses (the Option).

The Option will expire upon the earliest of: (a) the achievement of the pre-defined preclinical milestone, (b) termination by Ono of research and development activities for Candidate 2 and (c) the date that is the later of (i) four years after the Ono Agreement Effective Date and (ii) completion of all applicable activities contemplated under the joint development plan (the Option Period). The Company has maintained worldwide rights of manufacture for Candidate 2.

Under the terms of the Ono Agreement, Ono paid the Company an upfront, non-refundable and non-creditable payment of $10.0 million in connection with entering into the Ono Agreement. Additionally, as consideration for the Company’s conduct of research and preclinical development under a joint development plan, Ono pays the Company annual research and development fees set forth in the annual budget included in the joint development plan, which fees are estimated to be $20.0 million in aggregate over the course of the joint development plan.

Further, under the terms of the Ono Agreement, Ono has agreed to pay the Company up to an additional $20.0 million, subject to the exercise by Ono of the Option (Option Exercise Fees) during the Option Period for Candidate 2. Such fees are in addition to the upfront payment, research and development fees, and the previously paid $10.0 million milestone associated with the Ono Letter Agreement.

Subject to Ono’s exercise of the Option and to the achievement of certain clinical, regulatory and commercial milestones (the Ono Milestones) with respect to the Candidate in specified territories, the Company is entitled to receive an aggregate of up to $885.0 million in additional milestone payments for Candidate 2, with the applicable milestone payments for Candidate 2 for the United States and Europe subject to reduction by 50% if the Company elects to co-develop and co-commercialize Candidate 2 as described above. The Company is also eligible to receive tiered royalties (Royalties) ranging from the mid-single digits to the low-double digits based on annual net sales by Ono for Candidate 2 in specified territories, with such royalties subject to certain reductions.

No milestone payments specific to Candidate 1 are payable under the Ono Agreement, given the termination of the agreement with respect to such candidate.

The Ono Agreement will terminate with respect to a Candidate if Ono does not exercise its Option for a Candidate within the Option Period, or in its entirety if Ono does not exercise any of its Options for the Candidates within their respective Option Periods. In addition, either party may terminate the Ono Agreement in the event of breach, insolvency or patent challenges by the other party; provided, that Ono may terminate the Ono Agreement in its sole discretion (x) on a Candidate-by-Candidate basis at any time after the second anniversary of the effective date of the Ono Agreement or (y) on a Candidate-by-Candidate or country-by-country basis at any time after the expiration of the Option Period, subject to certain limitations. The Ono Agreement will expire on a Candidate-by-Candidate and country-by-country basis upon the expiration of the applicable royalty term, or in its entirety upon the expiration of all applicable payment obligations under the Ono Agreement.

The Company applied ASC 808 to the Ono Agreement and Ono Letter Agreement and determined that the agreements are applicable to such guidance. The Company concluded that Ono represented a customer and applied relevant guidance from ASC 606 to evaluate the appropriate accounting for the Ono Agreement and the Ono Letter Agreement. In accordance with this guidance, the Company identified its performance obligations, including its grant of a license to Ono to certain of its intellectual property subject to certain conditions, its conduct of research services, and its participation in a joint steering committee. The Company determined that its grant of a license to Ono to certain of its intellectual property subject to certain conditions was not distinct from other performance obligations because such grant is dependent on the conduct and results of the research services. Additionally, the Company determined that its conduct of research services was not distinct from other performance obligations since such conduct is dependent on the guidance of the joint steering committee. Accordingly, the Company determined that all performance obligations should be accounted for as one combined performance obligation, and that the combined performance obligation is transferred over the expected term of the conduct of the research services, which is estimated to be four years. The termination of the Ono Agreement with respect to Candidate 1 did not impact this assessment.

The Company also assessed, in connection with the upfront, non-refundable and non-creditable payment of $10.0 million received in September 2018 and the $5.0 million prepayment of the first-year research and development fees in October 2018, and concluded that there was not a significant financing component to the Ono Agreement.

The Company also assessed the effects of any variable elements under the Ono Agreement. Such assessment evaluated, among other things, the likelihood of receiving (i) preclinical milestone and option fees, (ii) various clinical, regulatory and commercial milestone payments, and (iii) royalties on net sales of either product Candidate. Based on its assessment, the Company concluded that, based on the likelihood of these variable components occurring, there was not a significant variable element included in the transaction price. Accordingly, the Company has not assigned a transaction price to any Ono Option Milestone, Ono Milestones or Ono Option Exercise Fees, other than the $10.0 million milestone triggered as part of the Ono Letter Agreement in December 2020, given the substantial uncertainty related to their achievement and has not assigned a transaction price to any Ono Royalties.

In accordance with ASC 606, the Company determined that the initial transaction price under the Ono Agreement equals $30.0 million, consisting of the upfront, non-refundable and non-creditable payment of $10.0 million and the aggregate estimated research and development fees of $20.0 million. The upfront payment of $10.0 million was recorded as deferred revenue and is being recognized as revenue over time in conjunction with the Company’s conduct of research services as the research services are the

primary component of the combined performance obligations. Revenue associated with the upfront payment will be recognized based on actual costs incurred as a percentage of the estimated total costs expected to be incurred over the expected term of conduct of the research services. The Company recorded the $5.0 million prepayment of the first-year research and development fees as deferred revenue, and such fees were recognized as revenue as the research services were delivered.

In accordance with ASC 606, the Company concluded that the $10.0 million milestone payment associated with the Ono Letter Agreement represented an increase in the initial transaction price under the Ono Agreement in the form of the receipt of variable consideration that was previously constrained. The Company recognized revenue associated with the $10.0 million milestone payment in an amount equal to the proportional percentage of actual costs incurred under the Ono Agreement as a percentage of the estimated total costs expected to be incurred over the expected term of conduct of the research services. The remaining unrecognized revenue associated with the $10.0 million milestone was recorded to deferred revenue and is being recognized as revenue over the expected term of conduct of research services.

In connection with the Ono Agreement and the Ono Letter Agreement, the Company has incurred $4.0 million in sublicense fees to certain of its existing licensors as of March 31, 2022. The $4.0 million in sublicense consideration represents an asset under ASC 340 and is being amortized to research and development expense ratably with the Company’s revenue recognition under the Ono Agreement. During the three months ended March 31, 2022 and 2021, the Company recognized $0.3 million and $0.2 million of such expense, respectively.

The Company recognized revenue of $2.5 million under the Ono Agreement for the three months ended March 31, 2022. Such revenue comprised $1.2 million associated with research services and $1.3 million associated with the upfront payment for the three months ended March 31, 2022. During the three months ended March 31, 2021, the Company recognized revenue of $2.5 million under the Ono Agreement. Such revenue comprised $1.3 million associated with research services and $1.2 million associated with the upfront payment for the three months ended March 31, 2021.

As of March 31, 2022, the Company has received $18.0 million in aggregate research and development fees from Ono.

Memorial Sloan Kettering Cancer Center License Agreement

On May 15, 2018, the Company entered into an Amended and Restated Exclusive License Agreement (the Amended MSK License) with Memorial Sloan Kettering Cancer Center (MSK). The Amended MSK License amends and restates the Exclusive License Agreement entered into between the Company and MSK on August 19, 2016 (the Original MSK License), pursuant to which the Company entered into an exclusive license agreement with MSK for rights relating to compositions and methods covering iPSC-derived cellular immunotherapy, including T-cells and NK-cells derived from iPSCs engineered with CARs.

Pursuant to the Amended MSK License, MSK granted to the Company additional licenses to certain patents and patent applications relating to new CAR constructs and off-the-shelf CAR T-cells, including the use of clustered regularly interspaced short palindromic repeat (CRISPR) and other innovative technologies for their production, in each case to research, develop, and commercialize licensed products in the field of all human therapeutic uses worldwide. The Company has the right to grant sublicenses to certain licensed rights in accordance with the terms of the Amended MSK License, in which case it is obligated to pay MSK a percentage of certain sublicense income received by the Company.

In the event a licensed product achieves a specified clinical milestone, MSK is then eligible to receive certain milestone payments totaling up to $75.0 million based on the price of the Company’s common stock, where the amount of such payments owed to MSK is contingent upon certain increases in the price of the Company’s common stock following the date of achievement of such clinical milestone. These payments are based on common stock price multiples, with the numerator being the fair value of the ten-trading day trailing average closing price of the Company’s common stock and the denominator being the ten-trading day trailing average closing price of the Company’s common stock as of the effective date of the Amended MSK License, adjusted for any stock splits, cash dividends, stock dividends, other distributions, combinations, recapitalizations, or similar events. Under the terms of the Amended MSK License, upon a change of control of the Company, in certain circumstances, the Company may be required to pay a portion of these payments to MSK based on the price of the Company’s common stock in connection with such change of control.

The following table summarizes the common stock multiples and the stock price appreciation milestone payments under the terms of the agreement:


Common stock multiple	5.0x		10.0x		15.0x
Ten-trading day trailing average common stock price	$	50.18	$	100.36	$	150.54
Stock price appreciation milestone payment (in millions)	$	20.0	$	30.0	$	25.0

In July 2021, the Company achieved the specified clinical milestone for a licensed product under the Amended MSK License and the Company’s ten-trading day trailing average common stock price exceeded the first, pre-specified threshold. As a result, the Company remitted the first milestone payment of $20.0 million to MSK during the year ended December 31, 2021.

To determine the estimated fair value of the remaining stock price appreciation milestones, the Company uses a Monte Carlo simulation methodology which models future Company common stock prices based on the current stock price and several key variables. The following variables were incorporated in the calculation of the estimated fair value of the stock price appreciation milestones as of March 31, 2022:


	As of March 31,			As of December 31,
	2022			2021
Risk-free interest rate		2.5	%		1.7	%
Expected volatility		77.7	%		77.6	%
Estimated term (in years)		16.8			17.0
Closing stock price as of remeasurement date	$	38.77		$	58.51

The key inputs to the Monte Carlo simulation to determine the fair value of the stock price appreciation milestones include the Company’s stock price as of the measurement date; the estimated term, which is based in part on the last valid patent claim date; the expected volatility of the Company’s common stock, estimated using the Company’s historical common stock volatility as of the measurement date; and the risk-free rate based on the U.S. Treasury yield for the estimated term determined. Fair value measurements are highly sensitive to changes in these inputs and significant changes could result in a significantly higher or lower fair value and resulting expense or gain.

At each balance sheet date, the Company remeasures the fair value of the stock price appreciation milestones, with changes in fair value recognized as a component of other income (expense) in the unaudited condensed consolidated statements of operations and comprehensive loss. Amounts are included in current or non-current liabilities based on the estimated timeline associated with the individual potential payments. During the three months ended March 31, 2022, the Company recorded $8.4 million of income associated with the change in fair value of the stock price appreciation milestones. As of March 31, 2022, the Company recorded a liability of $15.8 million associated with the stock price appreciation milestones for the Amended MSK License.

California Institute for Regenerative Medicine Award

3 Months Ended

Mar. 31, 2022

Award From California Institute For Regenerative Medicine Abstract

California Institute for Regenerative Medicine Award

3. California Institute for Regenerative Medicine Award

On April 5, 2018, the Company executed an award agreement with the California Institute for Regenerative Medicine (CIRM) pursuant to which CIRM awarded the Company $4.0 million to advance the Company’s FT516 product candidate into a first-in-human clinical trial for the treatment of subjects with advanced solid tumors, including in combination with monoclonal antibody therapy (the Award). Pursuant to the terms of the Award, the Company is eligible to receive five disbursements in varying amounts totaling $4.0 million, with one disbursement receivable upon the execution of the Award, and four disbursements receivable upon the completion of certain milestones throughout the project period. The Award is subject to certain co-funding requirements by the Company, and the Company is required to provide CIRM progress and financial update reports under the Award.

Pursuant to the terms of the Award, the Company, in its sole discretion, has the option to treat the Award either as a loan or as a grant. In the event the Company elects to treat the Award as a loan, the Company will be obligated to repay (i) 60%, (ii) 80%, (iii) 100% or (iv) 100% plus interest at 7% plus LIBOR, of the total Award to CIRM, where such repayment rate is dependent upon the phase of clinical development of FT516 at the time of the Company’s election. If the Company does not elect to treat the Award as a loan within 10 years of the date of the Award, the Award will be considered a grant and the Company will be obligated to pay to CIRM a royalty on commercial sales of FT516 until such royalty payments equal nine times the total amount awarded to the Company under the Award.

Since the Company may, at its election, repay some or all of the Award, the Company accounts for the Award as a liability until the time of election. As of March 31, 2022, the Company has received aggregate disbursements under the Award in the amount of $4.0 million. The aggregate amount received is recorded as a CIRM Liability on the accompanying unaudited condensed consolidated balance sheets and classified as current or non-current based on the potential amount payable within twelve months of the current balance sheet.

Investments

3 Months Ended

Mar. 31, 2022

Investments [Abstract]

Investments

4. Investments

The Company invests portions of excess cash in United States treasuries, non-U.S. government securities, municipal securities, corporate debt securities and commercial paper with maturities ranging from three to thirty-six months from the purchase date. These securities are classified as short-term and long-term investments in the accompanying unaudited condensed consolidated balance sheets based on each security’s contractual maturity date and are accounted for as available-for-sale securities.

The following table summarizes the Company’s investments accounted for as available-for-sale securities as of March 31, 2022 and December 31, 2021 (in thousands, except for maturity in years):


	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
March 31, 2022
Classified as current assets:
U.S. Treasury debt securities	1 or less	$	140,478	$	(773	)	$	3	$	139,708
Municipal securities	1 or less		16,847		(157	)		—		16,690
Corporate debt securities	1 or less		168,484		(491	)		—		167,993
Commercial paper	1 or less		184,976		(336	)		—		184,640
Total short-term investments		$	510,785	$	(1,757	)	$	3	$	509,031
Classified as non-current assets:
Municipal securities	Greater than 1	$	4,979	$	(39	)	$	—	$	4,940
Corporate debt securities	Greater than 1		64,070		(1,068	)		—		63,002
Total long-term investments		$	69,049	$	(1,107	)	$	—	$	67,942

December 31, 2021
Classified as current assets:
U.S. Treasury debt securities	1 or less	$	70,653	$	(163	)	$	—	$	70,490
Municipal securities	1 or less		18,017		(6	)		1		18,012
Corporate debt securities	1 or less		169,736		(187	)		—		169,549
Commercial paper	1 or less		224,333		(59	)		2		224,276
Total short-term investments		$	482,739	$	(415	)	$	3	$	482,327
Classified as non-current assets:
U.S. Treasury debt securities	Greater than 1	$	9,989	$	(35	)	$	—	$	9,954
Municipal securities	Greater than 1		9,034		(42	)		—		8,992
Corporate debt securities	Greater than 1		81,989		(271	)		—		81,718
Total long-term investments		$	101,012	$	(348	)	$	—	$	100,664

As of March 31, 2022 and December 31, 2021, the Company had $1.4 million and $1.1 million, respectively, of accrued interest on investments recorded in prepaid expenses and other assets on the unaudited condensed consolidated balance sheets.

The following tables present gross unrealized losses and fair values for those investments that were in an unrealized loss position as of March 31, 2022 and December 31, 2021, aggregated by investment category and the length of time that individual securities have been in a continuous loss position (in thousands):


	Less Than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
March 31, 2022
U.S. Treasury debt securities	$	129,711	$	(773	)	$	—	$	—		$	129,711	$	(773	)
Municipal securities		21,630		(196	)		—		—			21,630		(196	)
Corporate debt securities		202,366		(1,536	)		23,192		(23	)		225,558		(1,559	)
Commercial paper		66,900		(336	)		—		—			66,900		(336	)
Total	$	420,607	$	(2,841	)	$	23,192	$	(23	)	$	443,799	$	(2,864	)

December 31, 2021
U.S. Treasury debt securities	$	80,444	$	(198	)	$	—	$	—		$	80,444	$	(198	)
Municipal securities		23,352		(48	)		—		—			23,352		(48	)
Corporate debt securities		250,467		(458	)		—		—			250,467		(458	)
Commercial paper		59,863		(59	)		—		—			59,863		(59	)
Total	$	414,126	$	(763	)	$	—	$	—		$	414,126	$	(763	)

The Company reviews its investment holdings at the end of each reporting period and evaluates any unrealized losses using the expected credit loss model to determine if the unrealized loss is a result of a credit loss or other factors. The Company also evaluates its investment holdings for impairment using a variety of factors including the Company’s intent to sell the underlying securities prior to maturity and whether it is more likely than not that the Company would be required to sell the securities before the recovery of their amortized basis. During each of the three months ended March 31, 2022 and 2021, the Company did not recognize any impairment or realized gains or losses on sales of investments, and the Company did not record an allowance for, or recognize, any expected credit losses.

Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

5. Fair Value Measurements

The Company’s financial instruments consist primarily of cash and cash equivalents, marketable securities, accounts receivable, stock price appreciation milestones, accounts payable, and accrued liabilities. The carrying amounts of accounts receivable, accounts payable and accrued liabilities are considered to be representative of their respective fair values because of the relatively short-term nature of those instruments.

The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as 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 such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:

Level 1: Observable inputs such as quoted prices in active markets;

Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and

Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. The Company reviews the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy.

The following table presents the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2022 and December 31, 2021 (in thousands):


			Fair Value Measurements at Reporting Date Using
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of March 31, 2022
Financial assets:
Money market funds	$	64,741	$	64,741	$	—	$	—
U.S. Treasury debt securities		139,708		139,708		—		—
Municipal securities		21,630		—		21,630		—
Corporate debt securities		230,995		—		230,995		—
Commercial paper		184,640		—		184,640		—
Total financial assets measured at fair value on a recurring basis	$	641,714	$	204,449	$	437,265	$	—

Financial liabilities:
Stock price appreciation milestones	$	15,809	$	—	$	—	$	15,809
Total financial liabilities measured at fair value on a recurring basis	$	15,809	$	—	$	—	$	15,809

As of December 31, 2021
Financial assets:
Money market funds	$	133,583	$	133,583	$	—	$	—
U.S. Treasury debt securities		80,444		80,444		—		—
Municipal securities		27,004		—		27,004		—
Corporate debt securities		251,267		—		251,267		—
Commercial paper		224,276		—		224,276		—
Total assets measured at fair value on a recurring basis	$	716,574	$	214,027	$	502,547	$	—

Financial liabilities:
Stock price appreciation milestones	$	24,168	$	—	$	—	$	24,168
Total financial liabilities measured at fair value on a recurring basis	$	24,168	$	—	$	—	$	24,168

Level 1 assets consisted of money market funds and U.S. Treasury debt securities measured at fair value based on quoted prices in active markets as provided by the Company’s investment managers.

Level 2 assets consisted of non-U.S. government securities, municipal securities, corporate debt securities, and commercial paper measured at fair value using standard observable inputs, including reported trades, broker/dealer quotes, and bids and/or offers. The Company validates the quoted market prices provided by its investment managers by comparing the investment managers’ assessment of the fair values of the Company’s investment portfolio balance against the fair values of the Company’s investment portfolio balance obtained from an independent source.

There were no Level 3 assets held by the Company as of March 31, 2022.

Level 3 liabilities consisted of stock price appreciation milestones associated with the Amended MSK License as described in detail in Note 2. To determine the estimated fair value of the stock price appreciation milestones, the Company uses a Monte Carlo simulation methodology which models future Company common stock prices based on several key variables. The assumptions used to calculate the fair value of the stock price appreciation milestones are subject to a significant amount of judgment including the expected volatility of the Company’s common stock and estimated term, which is based in part on the last valid patent claim date. Fair value measurements are highly sensitive to changes in these inputs and significant changes could result in a significantly higher or lower fair value and resulting expense or gain. This assessment is based on several factors including the successful achievement of technological, manufacturing, and regulatory requirements.

A small change in the assumptions and other inputs, such as the price of the Company’s common stock, may have a relatively large change in the estimated fair value of the stock price appreciation milestones and associated liability and expense. For example,

keeping all other variables constant, a hypothetical 10% increase in the stock price at March 31, 2022 from $38.77 to $42.65 per share would have decreased the income recorded during the three months ended March 31, 2022 by $1.7 million related to the stock price appreciation milestones. Keeping all other variables constant, a hypothetical 10% decrease in the stock price at March 31, 2022 from $38.77 to $34.89 per share would have increased the income recorded during the three months ended March 31, 2022 by $1.6 million related to the stock price appreciation milestones.

The following table presents the changes in fair value of the Company’s Level 3 stock price appreciation milestones liability (in thousands):


Balance at December 31, 2021	$	24,168
Changes in fair value of stock price appreciation milestones liability		(8,359	)
Balance at March 31, 2022	$	15,809

None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented.

- Definition

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

+ References + Details

Accrued Expenses

3 Months Ended

Mar. 31, 2022

Payables and Accruals [Abstract]

Accrued Expenses

6. Accrued Expenses

Accrued Expenses

Current accrued expenses consist of the following (in thousands):


	March 31, 2022		December 31, 2021
Accrued payroll and other employee benefits	$	11,568	$	18,358
Accrued clinical trial related costs		10,511		12,344
Accrued other		13,031		11,710
Total current accrued expenses	$	35,110	$	42,412

Leases

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Leases

7. Leases

The Company has lease agreements for office, laboratory and manufacturing spaces that are classified as operating leases on the unaudited condensed consolidated balance sheets. These leases have terms varying from one to approximately sixteen years, with renewal options of up to ten years, as well as early termination options. Extension and termination options are included in the total lease term when the Company is reasonably certain to exercise them. The leases are subject to additional variable charges, including common area maintenance, property taxes, property insurance and other variable costs. Given the variable nature of such costs, they are recognized as expense as incurred. Additionally, some of the Company’s leases are subject to certain fixed fees which the Company has determined to be non-lease components. The Company has elected to combine and account for lease and non-lease components as a single-lease component for purposes of determining the total future lease payments.

As of March 31, 2022, future undiscounted minimum contractual payments under the Company’s operating leases were $188.9 million, which will be paid over a remaining weighted-average lease term of 12.1 years. The weighted-average discount rate for the operating lease liabilities was 6.9%, which was the Company’s incremental borrowing rate at lease commencement, as the discount rates implicit in the leases could not be readily determined.

The components of lease expense were as follows:


	Three Months Ended March 31,
	2022		2021
Straight-line lease expense	$	3,815	$	3,534
Variable lease expense		618		235
Total operating lease expense	$	4,433	$	3,769

No short-term lease expense was recognized during the three months ended March 31, 2022 and 2021.

Future minimum lease payments under the Company’s operating leases as of March 31, 2022 are as follows (in thousands):


	Operating Lease Payments
Remaining in 2022	$	11,285
2023		14,498
2024		14,836
2025		15,087
2026		15,540
2027		16,006
Thereafter		101,636
Total undiscounted lease payments	$	188,888
Less: imputed interest		(75,367	)
Total lease liability	$	113,521

Convertible Preferred Stock and Stockholders' Equity

3 Months Ended

Mar. 31, 2022

Convertible Preferred Stock And Stockholders Deficit Disclosure [Abstract]

Convertible Preferred Stock and Stockholders’ Equity

8. Convertible Preferred Stock and Stockholders’ Equity

Convertible Preferred Stock

In November 2016, the Company completed a private placement of stock in which investors, including investors affiliated with the directors and officers of the Company, purchased convertible preferred stock and common stock of the Company (the November 2016 Placement). The Company issued 2,819,549 shares of non-voting Class A Convertible Preferred Stock (the Class A Preferred) at $13.30 per share, each of which is convertible into five shares of common stock upon certain conditions defined in the Certificate of Designation of Preferences, Rights and Limitations of the Class A Preferred filed with the Delaware Secretary of State on November 22, 2016 (the CoD). The Class A Preferred were purchased exclusively by entities affiliated with Redmile Group, LLC (collectively, Redmile). The terms of the CoD prohibited Redmile from converting the Class A Preferred into shares of the Company’s common stock if, as a result of conversion, Redmile, together with its affiliates, would own more than 9.99% of the Company’s common stock then issued and outstanding (the Redmile Percentage Limitation), which percentage could change at Redmile’s election upon 61 days’ notice to the Company to (i) any other number less than or equal to 19.99% or (ii) subject to approval of the Company’s stockholders to the extent required in accordance with the Nasdaq Global Market rules, any number in excess of 19.99%. On May 2, 2017, the Company’s stockholders approved the issuance of up to an aggregate of 14,097,745 shares of common stock upon the conversion of the outstanding shares of Class A Preferred. As a result, Redmile has the right to increase the Redmile Percentage Limitation to any percentage in excess of 19.99% at its election. The Company also issued 7,236,837 shares of common stock at $2.66 per share as part of the November 2016 Placement.

The Class A Preferred are non-voting shares and have a stated par value of $0.001 per share and are convertible into five shares of the Company’s common stock at a conversion price of $2.66 per share, which was the fair value of the Company’s common stock on the date of issuance. Holders of the Class A Preferred have the same dividend rights as holders of the Company’s common stock. Additionally, the liquidation preferences of the Class A Preferred are pari passu among holders of the Company’s common stock and holders of the Class A Preferred, pro rata based on the number of shares held by each such holder (treated for this purpose as if the Class A Preferred had been converted to common stock).

During the year ended December 31, 2019, 25,000 shares of the Class A Preferred were converted into 125,000 shares of the Company’s common stock.

Pre-Funded Warrants

In January 2021, in conjunction with a public offering, the Company issued Pre-Funded Warrants, in lieu of common stock to certain investors, to purchase 257,310 shares of the Company’s common stock. The purchase price for the Pre-Funded Warrants was $85.499 per Pre-Funded Warrant, which equals the per share public offering price for the shares of common stock less the $0.001 exercise price for each such Pre-Funded Warrant. Given that the Pre-Funded Warrants are indexed to the Company’s own shares of common stock (and otherwise meet the requirements to be classified in equity), the Company recorded the consideration received from the issuance of the warrants as additional paid-in capital on the Company’s unaudited condensed consolidated balance sheets.

The Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise. A holder of Pre-Funded Warrants may increase or decrease this percentage not in excess of 19.99% by providing at least 61 days’ prior notice to the Company.

As of March 31, 2022, there were 257,310 Pre-Funded Warrants outstanding.

Stock Options and Restricted Stock Units

Stock option activity under all equity and stock option plans is summarized as follows:


	Number of Options			Weighted- Average Price
Balance at December 31, 2021		7,708,263		$	20.43
Granted		671,420			39.87
Exercised		(398,415	)		7.56
Cancelled		(51,924	)		33.61
Balance at March 31, 2022		7,929,344		$	22.63

Restricted stock unit activity under all equity and stock option plans is summarized as follows:


	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value per Share
Balance at December 31, 2021		4,008,832		$	58.60
Granted		2,293,106			40.49
Vested		(412,707	)		45.87
Cancelled		(98,518	)		56.29
Balance at March 31, 2022		5,790,713		$	52.54

The allocation of stock-based compensation for all stock awards is as follows (in thousands):


	Three Months Ended March 31,
	2022		2021
Research and development	$	12,694	$	8,522
General and administrative	$	6,637		4,454
Total	$	19,331	$	12,976

As of March 31, 2022, the unrecognized compensation cost related to outstanding options was $58.1 million and is expected to be recognized as expense over a weighted-average period of approximately 2.6 years.

As of March 31, 2022, the unrecognized compensation cost related to restricted stock units was $175.1 million which is expected to be recognized as expense over a weighted-average period of approximately 3.4 years.

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows:


	Three Months Ended March 31,
	2022			2021
Risk-free interest rate		1.6	%		0.4	%
Expected volatility		75.8	%		76.5	%
Expected term (in years)		5.6			5.1
Expected dividend yield		0.0	%		0.0	%

Reconciliation of Consolidated Stockholders’ Equity Accounts

The following table summarizes the Company’s changes in stockholders’ equity accounts for the three months ended March 31, 2022 (in thousands, except share data):


	Convertible Preferred Stock				Common Stock				Additional Paid-in		Accumulated Other Comprehensive			Accumulated			Total Stockholders'
	Shares		Amount		Shares		Amount		Capital		Gain (Loss)			Deficit			Equity
Balance at December 31, 2021		2,794,549	$	3		95,726,962	$	96	$	1,448,584	$	(762	)	$	(769,083	)	$	678,838
Exercise of stock options, net of issuance costs		—		—		398,415		—		3,001		—			—			3,001
Issuance of common stock upon vesting of restricted stock units		—		—		412,707		1		—		—			—			1
Stock-based compensation		—		—		—		—		19,331		—			—			19,331
Unrealized loss on investments		—		—		—		—		—		(2,088	)		—			(2,088	)
Net loss		—		—		—		—		—		—			(65,690	)		(65,690	)
Balance at March 31, 2022		2,794,549	$	3		96,538,084	$	97	$	1,470,916	$	(2,850	)	$	(834,773	)	$	633,393

The following table summarizes the Company’s changes in stockholders’ equity accounts for the three months ended March 31, 2021 (in thousands, except share data):


	Convertible Preferred Stock				Common Stock				Additional Paid-in		Accumulated Other Comprehensive			Accumulated			Total Stockholders'
	Shares		Amount		Shares		Amount		Capital		Gain			Deficit			Equity
Balance at December 31, 2020		2,794,549	$	3		87,722,237	$	88	$	941,216	$	70		$	(556,932	)	$	384,445
Exercise of stock options, net of issuance costs		—		—		613,015		1		5,647		—			—			5,648
Issuance of common stock upon vesting of restricted stock units		—		—		430,620		—		—		—			—			—
Stock-based compensation		—		—		—		—		12,976		—			—			12,976
Public offering of common stock and issuance of pre-funded warrants, net of issuance costs		—		—		5,122,807		5		432,440		—			—			432,445
Unrealized loss on investments		—		—		—		—		—		(330	)		—			(330	)
Net loss		—		—		—		—		—		—			(45,089	)		(45,089	)
Balance at March 31, 2021		2,794,549	$	3		93,888,679	$	94	$	1,392,279	$	(260	)	$	(602,021	)	$	790,095

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-URI http://asc.fasb.org/topic&trid=2208762

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496171-112644

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496189-112644

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 16
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496180-112644

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Subsequent Events

3 Months Ended

Mar. 31, 2022

Subsequent Events [Abstract]

Subsequent Events [Text Block]

9. Subsequent Events

In April 2022, the Company achieved a research milestone associated with a product candidate directed to a third tumor-associated antigen under the Janssen Agreement; the amount due under the milestone is $3.0 million.

Organization and Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Public Equity Offerings

Use of Estimates

Risks and Uncertainties

Principles of Consolidation

Cash, Cash Equivalents and Restricted Cash


	Three Months Ended March 31,
	2022		2021
Cash and cash equivalents	$	64,741	$	106,413
Restricted cash		15,227		15,227
Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statement of cash flows	$	79,968	$	121,640

Investments

Unaudited Interim Financial Information

Revenue Recognition

Stock Price Appreciation Milestones

Leases

Stock-Based Compensation

Convertible Preferred Stock

Comprehensive Loss

Net Loss per Common Share

Going Concern Assessment

Organization and Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Reconciliation of Cash, Cash Equivalents, and Restricted Cash


	Three Months Ended March 31,
	2022		2021
Cash and cash equivalents	$	64,741	$	106,413
Restricted cash		15,227		15,227
Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statement of cash flows	$	79,968	$	121,640

Collaboration and License Agreements (Tables)

3 Months Ended

Mar. 31, 2022

Collaboration And License Agreements Disclosure [Abstract]

Summary of all Possible Stock Price Appreciation Milestone Payments

The following table summarizes the common stock multiples and the stock price appreciation milestone payments under the terms of the agreement:


Common stock multiple	5.0x		10.0x		15.0x
Ten-trading day trailing average common stock price	$	50.18	$	100.36	$	150.54
Stock price appreciation milestone payment (in millions)	$	20.0	$	30.0	$	25.0

Schedule of Determine the Estimated Fair Value of the Stock Price Appreciation Milestones Payments

The following variables were incorporated in the calculation of the estimated fair value of the stock price appreciation milestones as of March 31, 2022:


	As of March 31,			As of December 31,
	2022			2021
Risk-free interest rate		2.5	%		1.7	%
Expected volatility		77.7	%		77.6	%
Estimated term (in years)		16.8			17.0
Closing stock price as of remeasurement date	$	38.77		$	58.51

Investments (Tables)

3 Months Ended

Mar. 31, 2022

Investments [Abstract]

Summary of Investments

The following table summarizes the Company’s investments accounted for as available-for-sale securities as of March 31, 2022 and December 31, 2021 (in thousands, except for maturity in years):


	Maturity (in years)	Amortized Cost		Unrealized Losses			Unrealized Gains		Estimated Fair Value
March 31, 2022
Classified as current assets:
U.S. Treasury debt securities	1 or less	$	140,478	$	(773	)	$	3	$	139,708
Municipal securities	1 or less		16,847		(157	)		—		16,690
Corporate debt securities	1 or less		168,484		(491	)		—		167,993
Commercial paper	1 or less		184,976		(336	)		—		184,640
Total short-term investments		$	510,785	$	(1,757	)	$	3	$	509,031
Classified as non-current assets:
Municipal securities	Greater than 1	$	4,979	$	(39	)	$	—	$	4,940
Corporate debt securities	Greater than 1		64,070		(1,068	)		—		63,002
Total long-term investments		$	69,049	$	(1,107	)	$	—	$	67,942

December 31, 2021
Classified as current assets:
U.S. Treasury debt securities	1 or less	$	70,653	$	(163	)	$	—	$	70,490
Municipal securities	1 or less		18,017		(6	)		1		18,012
Corporate debt securities	1 or less		169,736		(187	)		—		169,549
Commercial paper	1 or less		224,333		(59	)		2		224,276
Total short-term investments		$	482,739	$	(415	)	$	3	$	482,327
Classified as non-current assets:
U.S. Treasury debt securities	Greater than 1	$	9,989	$	(35	)	$	—	$	9,954
Municipal securities	Greater than 1		9,034		(42	)		—		8,992
Corporate debt securities	Greater than 1		81,989		(271	)		—		81,718
Total long-term investments		$	101,012	$	(348	)	$	—	$	100,664

Aggregated by investment category and the length of time

aggregated by investment category and the length of time that individual securities have been in a continuous loss position (in thousands):


	Less Than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses
March 31, 2022
U.S. Treasury debt securities	$	129,711	$	(773	)	$	—	$	—		$	129,711	$	(773	)
Municipal securities		21,630		(196	)		—		—			21,630		(196	)
Corporate debt securities		202,366		(1,536	)		23,192		(23	)		225,558		(1,559	)
Commercial paper		66,900		(336	)		—		—			66,900		(336	)
Total	$	420,607	$	(2,841	)	$	23,192	$	(23	)	$	443,799	$	(2,864	)

December 31, 2021
U.S. Treasury debt securities	$	80,444	$	(198	)	$	—	$	—		$	80,444	$	(198	)
Municipal securities		23,352		(48	)		—		—			23,352		(48	)
Corporate debt securities		250,467		(458	)		—		—			250,467		(458	)
Commercial paper		59,863		(59	)		—		—			59,863		(59	)
Total	$	414,126	$	(763	)	$	—	$	—		$	414,126	$	(763	)

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on Recurring Basis

The following table presents the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2022 and December 31, 2021 (in thousands):


			Fair Value Measurements at Reporting Date Using
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
As of March 31, 2022
Financial assets:
Money market funds	$	64,741	$	64,741	$	—	$	—
U.S. Treasury debt securities		139,708		139,708		—		—
Municipal securities		21,630		—		21,630		—
Corporate debt securities		230,995		—		230,995		—
Commercial paper		184,640		—		184,640		—
Total financial assets measured at fair value on a recurring basis	$	641,714	$	204,449	$	437,265	$	—

Financial liabilities:
Stock price appreciation milestones	$	15,809	$	—	$	—	$	15,809
Total financial liabilities measured at fair value on a recurring basis	$	15,809	$	—	$	—	$	15,809

As of December 31, 2021
Financial assets:
Money market funds	$	133,583	$	133,583	$	—	$	—
U.S. Treasury debt securities		80,444		80,444		—		—
Municipal securities		27,004		—		27,004		—
Corporate debt securities		251,267		—		251,267		—
Commercial paper		224,276		—		224,276		—
Total assets measured at fair value on a recurring basis	$	716,574	$	214,027	$	502,547	$	—

Financial liabilities:
Stock price appreciation milestones	$	24,168	$	—	$	—	$	24,168
Total financial liabilities measured at fair value on a recurring basis	$	24,168	$	—	$	—	$	24,168

Summary of Changes in the Fair Value of the Company's Level 3 Enterprise Fair Value Milestone Payment Liability

The following table presents the changes in fair value of the Company’s Level 3 stock price appreciation milestones liability (in thousands):


Balance at December 31, 2021	$	24,168
Changes in fair value of stock price appreciation milestones liability		(8,359	)
Balance at March 31, 2022	$	15,809

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2022

Payables and Accruals [Abstract]

Schedule of accrued expenses

Current accrued expenses consist of the following (in thousands):


	March 31, 2022		December 31, 2021
Accrued payroll and other employee benefits	$	11,568	$	18,358
Accrued clinical trial related costs		10,511		12,344
Accrued other		13,031		11,710
Total current accrued expenses	$	35,110	$	42,412

Leases (Tables)

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Schedule of Components of Lease Expense

The components of lease expense were as follows:


	Three Months Ended March 31,
	2022		2021
Straight-line lease expense	$	3,815	$	3,534
Variable lease expense		618		235
Total operating lease expense	$	4,433	$	3,769

Schedule of Future Minimum Payments Under Non-cancelable Operating Leases

Future minimum lease payments under the Company’s operating leases as of March 31, 2022 are as follows (in thousands):


	Operating Lease Payments
Remaining in 2022	$	11,285
2023		14,498
2024		14,836
2025		15,087
2026		15,540
2027		16,006
Thereafter		101,636
Total undiscounted lease payments	$	188,888
Less: imputed interest		(75,367	)
Total lease liability	$	113,521

Convertible Preferred Stock and Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2022

Convertible Preferred Stock And Stockholders Equity Disclosure [Abstract]

Summary of stock option activity under the Plan

Stock option activity under all equity and stock option plans is summarized as follows:


	Number of Options			Weighted- Average Price
Balance at December 31, 2021		7,708,263		$	20.43
Granted		671,420			39.87
Exercised		(398,415	)		7.56
Cancelled		(51,924	)		33.61
Balance at March 31, 2022		7,929,344		$	22.63

Summary of restricted stock unit activity under the Plan

Restricted stock unit activity under all equity and stock option plans is summarized as follows:


	Number of Restricted Stock Units			Weighted- Average Grant Date Fair Value per Share
Balance at December 31, 2021		4,008,832		$	58.60
Granted		2,293,106			40.49
Vested		(412,707	)		45.87
Cancelled		(98,518	)		56.29
Balance at March 31, 2022		5,790,713		$	52.54

Schedule of allocation of stock-based compensation for all stock awards

The allocation of stock-based compensation for all stock awards is as follows (in thousands):


	Three Months Ended March 31,
	2022		2021
Research and development	$	12,694	$	8,522
General and administrative	$	6,637		4,454
Total	$	19,331	$	12,976

Schedule of weighted-average assumptions used to determine the fair value of employee and nonemployee stock option grants

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows:


	Three Months Ended March 31,
	2022			2021
Risk-free interest rate		1.6	%		0.4	%
Expected volatility		75.8	%		76.5	%
Expected term (in years)		5.6			5.1
Expected dividend yield		0.0	%		0.0	%

Summary of changes in stockholders' equity

The following table summarizes the Company’s changes in stockholders’ equity accounts for the three months ended March 31, 2022 (in thousands, except share data):


	Convertible Preferred Stock				Common Stock				Additional Paid-in		Accumulated Other Comprehensive			Accumulated			Total Stockholders'
	Shares		Amount		Shares		Amount		Capital		Gain (Loss)			Deficit			Equity
Balance at December 31, 2021		2,794,549	$	3		95,726,962	$	96	$	1,448,584	$	(762	)	$	(769,083	)	$	678,838
Exercise of stock options, net of issuance costs		—		—		398,415		—		3,001		—			—			3,001
Issuance of common stock upon vesting of restricted stock units		—		—		412,707		1		—		—			—			1
Stock-based compensation		—		—		—		—		19,331		—			—			19,331
Unrealized loss on investments		—		—		—		—		—		(2,088	)		—			(2,088	)
Net loss		—		—		—		—		—		—			(65,690	)		(65,690	)
Balance at March 31, 2022		2,794,549	$	3		96,538,084	$	97	$	1,470,916	$	(2,850	)	$	(834,773	)	$	633,393

The following table summarizes the Company’s changes in stockholders’ equity accounts for the three months ended March 31, 2021 (in thousands, except share data):


	Convertible Preferred Stock				Common Stock				Additional Paid-in		Accumulated Other Comprehensive			Accumulated			Total Stockholders'
	Shares		Amount		Shares		Amount		Capital		Gain			Deficit			Equity
Balance at December 31, 2020		2,794,549	$	3		87,722,237	$	88	$	941,216	$	70		$	(556,932	)	$	384,445
Exercise of stock options, net of issuance costs		—		—		613,015		1		5,647		—			—			5,648
Issuance of common stock upon vesting of restricted stock units		—		—		430,620		—		—		—			—			—
Stock-based compensation		—		—		—		—		12,976		—			—			12,976
Public offering of common stock and issuance of pre-funded warrants, net of issuance costs		—		—		5,122,807		5		432,440		—			—			432,445
Unrealized loss on investments		—		—		—		—		—		(330	)		—			(330	)
Net loss		—		—		—		—		—		—			(45,089	)		(45,089	)
Balance at March 31, 2021		2,794,549	$	3		93,888,679	$	94	$	1,392,279	$	(260	)	$	(602,021	)	$	790,095

Organization and Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net loss		$ (65,690)	$ (45,089)
Potentially dilutive securities (in shares)		27,700,000	25,500,000
Letters of credit outstanding amount		$ 15,200	$ 15,200
Restricted Stock Units (RSUs) \| Common Stock Options
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potentially dilutive securities (in shares)		13,700,000	11,600,000
Class A Convertible Preferred Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potentially dilutive securities (in shares)		14,000,000.0	14,000,000.0
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Short-term leases term excluded from calculation of ROU and lease liabilities		12 months
January 2021 Public Offering
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of common stock in conjunction with public offering (in shares)	5,100,000
Share issue price (in dollars per share)	$ 85.50
Aggregate purchase price of common stock	$ 460,000
Net proceeds from issuance of shares after related cash costs	432,400
Costs related to equity offering	$ 27,600
Pre-Funded Warrants
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares to be purchased	257,310	257,310
Purchase price of prefunded warrants	$ 85.499
Exercise price of warrants	$ 0.001
Pre Funded Common Stock Warrant \| January 2021 Public Offering
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of shares to be purchased	257,310

Organization and Summary of Significant Accounting Policies (Details 2) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 64,741	$ 133,583	$ 106,413
Restricted cash	15,227		15,227
Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statement of cash flows	$ 79,968	$ 148,810	$ 121,640	$ 182,574

Collaboration and License Agreements - Janssen Collaboration and Option Agreement (Details) - USD ($)			1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 07, 2020	Apr. 02, 2020	Jun. 30, 2020	Mar. 31, 2022	Mar. 31, 2021	Jun. 30, 2020	Dec. 31, 2021
Collaboration agreement
Collaboration contract asset				$ 8,777,000			$ 9,870,000
Revenue recognized				18,414,000	$ 11,142,000
Janssen Biotech Inc
Collaboration agreement
Upfront, non-refundable and non-creditable payment		$ 50,000,000.0		50,000,000.0
Transaction price of the agreement		66,000,000.0
Equity premium		16,000,000.0
Non-refundable upfront payments recorded as deferred revenue		$ 66,000,000.0
Milestone receivable				3,000,000.0
Milestone receivable with increase in initial transaction price				3,000,000.0
Milestone receivable to deferred revenue				3,000,000.0
Collaboration contract asset				14,000,000.0
Amortization of sublicense consideration				1,100,000	400,000
Revenue recognized				15,900,000	8,600,000
Deferred revenue				45,100,000
Deferred revenue classified as current				22,600,000
Research and development fees cash payments received				39,900
Janssen Biotech Inc \| Research And Development
Collaboration agreement
Revenue recognized				9,800,000	6,800,000
Janssen Biotech Inc \| Upfront Fee and Equity Premium
Collaboration agreement
Revenue recognized				6,100,000	$ 1,800,000
Janssen Biotech Inc \| Sublicense Consideration
Collaboration agreement
Collaboration contract asset				$ 8,800,000
Johnson Johnson Innovation J J D C Inc \| Stock Purchase Agreement
Collaboration agreement
Issuance of common stock in conjunction with public offering (in shares)				1,600,000
Common stock per share				$ 31.00
Aggregate purchase price of common stock				$ 50,000,000.0
Equity premium per share				$ 9.93
Aggregate equity premium on shares				$ 16,000,000.0
Proceeds from public offering of common stock, net of issuance costs				$ 34,000,000.0
Johnson Johnson Innovation J J D C Inc \| Stock Purchase Agreement \| Private Placement
Collaboration agreement
Issuance of common stock in conjunction with public offering (in shares)				50,000,000.0
Proceeds from public offering of common stock, net of issuance costs			$ 50,000,000.0
Share issue price (in dollars per share)			$ 28.31			$ 28.31
Issuance of common stock during period for private placements (in shares)						1,800,000
First Janssen Cancer Target \| Maximum \| Janssen Agreement
Collaboration agreement
Development, regulatory, and sales milestones	$ 898,000,000.0
Additional candidate milestone Payments	460,000,000.0
Additional Cancer Targets \| Maximum \| Janssen Agreement
Collaboration agreement
Development, regulatory, and sales milestones	706,000,000.0
Additional candidate milestone Payments	$ 340,000,000.0

Collaboration and License Agreements - Ono Collaboration and Option Agreement (Details) - USD ($)		1 Months Ended	3 Months Ended
	Sep. 14, 2018	Oct. 31, 2018	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 04, 2020
Collaboration agreement
Collaboration contract asset			$ 8,777,000		$ 9,870,000
Revenue recognized			$ 18,414,000	$ 11,142,000
Expected Ressarch Services Period			4 years
Ono Pharmaceutical Co. Ltd
Collaboration agreement
Milestone payments	$ 10,000,000.0
Non-refundable upfront payments recorded as deferred revenue	10,000,000.0
Aggregate research and development fees payments receivable	20,000,000.0
Collaborative arrangement annual payments receivable recorded as deferred revenue		$ 5,000,000.0
Collaborative arrangement potential additional milestones	20,000,000.0
First-year research and development fees prepayment		$ 5,000,000.0
Transaction price of the agreement	$ 30,000,000.0
Sublicense consideration paid			$ 4,000,000.0
Collaboration contract asset			4,000,000.0
Amortization of sublicense consideration			300,000	200,000
Revenue recognized			2,500,000
Research and development fees cash payments received			18,000,000.0
Ono Pharmaceutical Co. Ltd \| Candidate 2
Collaboration agreement
Percentage of reduction on milestone payments	50.00%
Ono Pharmaceutical Co. Ltd \| Maximum \| Candidate 2
Collaboration agreement
Aggregate milestone payments	$ 885,000,000.0
Ono Pharmaceutical Co. Ltd \| Collaborative Arrangement \| Research services
Collaboration agreement
Revenue recognized			1,300,000	2,500,000
Ono Pharmaceutical Co. Ltd \| Collaborative Arrangement \| Upfront Fee
Collaboration agreement
Revenue recognized			1,300,000	$ 1,200,000
Ono Pharmaceutical Co. Ltd \| Collaborative Arrangement \| Minimum
Collaboration agreement
Profits and losses sharing percentage	50.00%
Ono Letter Agreement \| Ono Pharmaceutical Co. Ltd
Collaboration agreement
Milestone payments						$ 10,000,000.0
Milestone payments recorded to deferred revenue	$ 10,000,000.0
Revenue recognized			$ 1,200,000

Collaboration and License Agreements - Memorial Sloan Kettering Cancer Center License Agreement (Details) - Amended MSK License - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Collaboration agreement
Enterprise value milestone payment	$ 75.0
Stock price appreciation milestone payable		$ 20.0
Change in fair value of enterprise value milestones	8.4
Enterprise value milestones liability at fair value	$ 15.8

Collaboration and License Agreements (Details 1) - Amended MSK License $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) $ / shares
Milestone One
Collaboration agreement
Common stock multiple	5.0x
Ten-trading day trailing average common stock price \| $ / shares	$ 50.18
Stock price appreciation milestone payment (in millions) \| $	$ 20.0
Milestone Two
Collaboration agreement
Common stock multiple	10.0x
Ten-trading day trailing average common stock price \| $ / shares	$ 100.36
Stock price appreciation milestone payment (in millions) \| $	$ 30.0
Milestone Three
Collaboration agreement
Common stock multiple	15.0x
Ten-trading day trailing average common stock price \| $ / shares	$ 150.54
Stock price appreciation milestone payment (in millions) \| $	$ 25.0

Collaboration and License Agreements (Details 2) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Determine the estimated fair value of the enterprise value milestone payments
Closing stock price as of re measurement date	$ 38.77
Amended MSK License
Determine the estimated fair value of the enterprise value milestone payments
Risk-free interest rate	2.50%	1.70%
Expected volatility	77.70%	77.60%
Estimated term (in years)	16 years 9 months 18 days	17 years
Closing stock price as of re measurement date	$ 38.77	$ 58.51

California Institute For Regenerative Medicine Award (Details) $ in Millions		3 Months Ended	12 Months Ended
	Apr. 05, 2018 USD ($) Disbursement	Mar. 31, 2022 USD ($)	Dec. 31, 2020
Award from California institute for regenerative medicine
Period to treat award as grant, if award not treated as loan			10 years
California Institute for Regenerative Medicine
Award from California institute for regenerative medicine
Receipt of first disbursement under the Award \| $		$ 4.0
California Institute for Regenerative Medicine \| LIBOR
Award from California institute for regenerative medicine
Award considered as a loan, interest rate	7.00%
California Institute for Regenerative Medicine \| Loan Repayment Rate One
Award from California institute for regenerative medicine
Repayment percentage of award amount	60.00%
California Institute for Regenerative Medicine \| Loan Repayment Rate Two
Award from California institute for regenerative medicine
Repayment percentage of award amount	80.00%
California Institute for Regenerative Medicine \| Loan Repayment Rate Three
Award from California institute for regenerative medicine
Repayment percentage of award amount	100.00%
California Institute for Regenerative Medicine \| Loan Repayment Rate Four
Award from California institute for regenerative medicine
Repayment percentage of award amount	100.00%
California Institute for Regenerative Medicine \| FT516
Award from California institute for regenerative medicine
Award agreement executed date	Apr. 05, 2018
Award for first-in-human clinical trial \| $	$ 4.0
Number of disbursements \| Disbursement	5
Number of disbursement receivable upon the execution of the award \| Disbursement	1
Number of disbursements receivable based on completion of certain operating milestones \| Disbursement	4
Additional amount available for funding under award \| $	$ 4.0

Investments (Details) - USD ($)	3 Months Ended
Investments (Details) - USD ($)	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, impairment	$ 0	$ 0
Available-for-sale securities, realized gains (losses) on sales	0	0
Available-for-sale securities, recognition of expected credit losses	0	$ 0
Prepaid Expenses And Other Assets
Schedule Of Available For Sale Securities [Line Items]
Accured Interest on investments	$ 1,400,000		$ 1,100,000
Treasuries, Non-U.S. Government Securities, Municipal Securities, Corporate Debt Securities and Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Short term investments, maturity start range	3 months
Short term investments, maturity end range	36 months

Investments (Details 2) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Investments (Details 2) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)		1 or les
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 510,785	$ 482,739
Unrealized Losses	(1,757)	(415)
Unrealized Gains	3	3
Estimated Fair Value	509,031	482,327
Long-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	69,049	101,012
Unrealized Losses	(1,107)	(348)
Estimated Fair Value	$ 67,942	$ 100,664
U.S. Treasury debt securities \| Current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	1 or less	1 or less
Amortized Cost	$ 140,478	$ 70,653
Unrealized Losses	(773)	(163)
Unrealized Gains	3
Estimated Fair Value	$ 139,708	$ 70,490
U.S. Treasury debt securities \| Non-current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)		Greater than 1
Amortized Cost		$ 9,989
Unrealized Losses		(35)
Estimated Fair Value		9,954
Municipal securities \| Current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	1 or less
Amortized Cost	$ 16,847	18,017
Unrealized Losses	(157)	(6)
Unrealized Gains		1
Estimated Fair Value	$ 16,690	$ 18,012
Municipal securities \| Non-current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	Greater than 1	Greater than 1
Amortized Cost	$ 4,979	$ 9,034
Unrealized Losses	(39)	(42)
Estimated Fair Value	$ 4,940	8,992
Corporate debt securities \| Current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	1 or less
Amortized Cost	$ 168,484	169,736
Unrealized Losses	(491)	(187)
Estimated Fair Value	$ 167,993	$ 169,549
Corporate debt securities \| Non-current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	Greater than 1	Greater than 1
Amortized Cost	$ 64,070	$ 81,989
Unrealized Losses	(1,068)	(271)
Estimated Fair Value	$ 63,002	$ 81,718
Commercial Paper \| Current Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Maturity (in years)	1 or less	1 or less
Amortized Cost	$ 184,976	$ 224,333
Unrealized Losses	(336)	(59)
Unrealized Gains		2
Estimated Fair Value	$ 184,640	$ 224,276

Investments (Details 3) - Short Term Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Total	$ 443,799	$ 414,126
Unrealized Losses, Total	2,864	763
U.S. Treasury debt securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Total	129,711	80,444
Unrealized Losses, Total	773	198
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Total	21,630	23,352
Unrealized Losses, Total	196	48
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Total	225,558	250,467
Unrealized Losses, Total	1,559	458
Commercial Paper
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Total	66,900	59,863
Unrealized Losses, Total	336	59
Short-term Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less Than 12 Months	420,607	414,126
Unrealized Losses, Less Than 12 Months	2,841	763
Short-term Investments [Member] \| U.S. Treasury debt securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less Than 12 Months	129,711	80,444
Unrealized Losses, Less Than 12 Months	773	198
Short-term Investments [Member] \| Municipal securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less Than 12 Months	21,630	23,352
Unrealized Losses, Less Than 12 Months	196	48
Short-term Investments [Member] \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less Than 12 Months	202,366	250,467
Unrealized Losses, Less Than 12 Months	1,536	458
Short-term Investments [Member] \| Commercial Paper
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, Less Than 12 Months	66,900	59,863
Unrealized Losses, Less Than 12 Months	336	59
Long-term Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, 12 Months or Greater	23,192	0
Unrealized Losses, 12 Months or Greater	23
Long-term Investments [Member] \| U.S. Treasury debt securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	0
Long-term Investments [Member] \| Municipal securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	0
Long-term Investments [Member] \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, 12 Months or Greater	23,192
Unrealized Losses, 12 Months or Greater	23
Long-term Investments [Member] \| Commercial Paper
Debt Securities, Available-for-sale [Line Items]
Estimated Fair Value, 12 Months or Greater	0
Unrealized Losses, 12 Months or Greater	$ 0

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Quoted prices in Active Market for Identical Assets (Level 1) \| Money market funds
Financial assets:
Money market funds	$ 64,741	$ 133,583
Quoted prices in Active Market for Identical Assets (Level 1) \| U.S. Treasury debt securities
Financial assets:
Investment	139,708	80,444
Significant Other Observable Inputs (Level 2) \| Municipal securities
Financial assets:
Investment	21,630	27,004
Significant Other Observable Inputs (Level 2) \| Corporate debt securities
Financial assets:
Investment	230,995	251,267
Significant Other Observable Inputs (Level 2) \| Commercial Paper
Financial assets:
Investment	184,640	224,276
Fair Value Measurements Recurring
Financial assets:
Total financial assets measured at fair value on a recurring basis	641,714	716,574
Financial liabilities:
Total financial liabilities measured at fair value on a recurring basis	15,809	24,168
Fair Value Measurements Recurring \| Stock price appreciation milestones
Financial liabilities:
Stock price appreciation milestones	15,809	24,168
Fair Value Measurements Recurring \| Money market funds
Financial assets:
Money market funds	64,741	133,583
Fair Value Measurements Recurring \| U.S. Treasury debt securities
Financial assets:
Investment	139,708	80,444
Fair Value Measurements Recurring \| Non-U.S. government securities
Financial assets:
Investment		251,267
Fair Value Measurements Recurring \| Municipal securities
Financial assets:
Investment	21,630	27,004
Fair Value Measurements Recurring \| Corporate debt securities
Financial assets:
Investment	230,995
Fair Value Measurements Recurring \| Commercial Paper
Financial assets:
Investment	184,640	224,276
Fair Value Measurements Recurring \| Quoted prices in Active Market for Identical Assets (Level 1)
Financial assets:
Total financial assets measured at fair value on a recurring basis	204,449	214,027
Fair Value Measurements Recurring \| Significant Other Observable Inputs (Level 2)
Financial assets:
Total financial assets measured at fair value on a recurring basis	437,265	502,547
Fair Value Measurements Recurring \| Significant Unobservable Inputs (Level 3)
Financial liabilities:
Total financial liabilities measured at fair value on a recurring basis	15,809	24,168
Fair Value Measurements Recurring \| Significant Unobservable Inputs (Level 3) \| Stock price appreciation milestones
Financial liabilities:
Stock price appreciation milestones	$ 15,809	$ 24,168

Fair Value Measurements (Details 2) - USD ($)	3 Months Ended
Fair Value Measurements (Details 2) - USD ($)	Mar. 31, 2022	Mar. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Closing stock price as of re measurement date	$ 38.77
Change in fair value of stock price appreciation milestones	$ (8,359,000)	$ (744,000)
Transfer of assets from level 1 to level 2	0
Transfer of assets from level 2 to level 1	0
Transfer of liabilities from level 1 to level 3	0
Transfer of liabilities from level 3 to level 1	0
Transfer of liabilities from level 2 to level 3	0
Transfer of liabilities from level 3 to level 2	0
Fair Value Measurements Nonrecurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets/ Non-financial assets	0
Total financial liabilities measured at fair value on a recurring basis	$ 0
Stock price increased by 10% per share
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Sensitivity analysis fair value inputs stock price increase/decrease	10.00%
Sensitivity analysis share price fair value input	$ 42.65
Change in fair value of stock price appreciation milestones	$ 1,700,000
Stock price decreased by 10% per share
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Sensitivity analysis fair value inputs stock price increase/decrease	10.00%
Sensitivity analysis share price fair value input	$ 34.89
Change in fair value of stock price appreciation milestones	$ 1,600,000

Fair Value Measurements (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value of stock price appreciation milestones	$ (8,359)	$ (744)
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance at the beginning of the period	24,168
Change in fair value of stock price appreciation milestones	(8,359)
Balance at the end of the period	$ 15,809

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current accrued expenses
Accrued payroll and other employee benefits	$ 11,568	$ 18,358
Accrued clinical trial related costs	10,511	12,344
Accrued other	13,031	11,710
Total current accrued expenses	$ 35,110	$ 42,412

Leases (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
Leases (Details) - USD ($) $ in Thousands	Jan. 31, 2020	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021
Lessee Lease Description [Line Items]
Lessee, operating lease, option to extend		These leases have terms varying from one to approximately sixteen years, with renewal options of up to ten years
Lessee, operating lease, existence of option to extend				true
Letters of credit outstanding amount		$ 15,200	$ 15,200
Future minimum payments under the operating leases		$ 188,888
Remaining weighted-average lease term		12 years 1 month 6 days
Operating lease liabilities, weighted-average discount rate		6.90%
Total short-term lease expense		$ 0	$ 0
The Premises 2020 Lease Agreement
Lessee Lease Description [Line Items]
Lessee, operating lease, existence of option to extend	true
Minimum
Lessee Lease Description [Line Items]
Lease term		1 year
Future minimum payments under the operating leases		$ 188,900
Maximum
Lessee Lease Description [Line Items]
Lease term		16 years
Maximum \| The Premises 2020 Lease Agreement
Lessee Lease Description [Line Items]
Renewal term				10 years

Leases (Details 1) - USD ($) $ in Thousands	3 Months Ended
Leases (Details 1) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2021
Lease, Cost [Abstract]
Straight-line lease expense	$ 3,815	$ 3,534
Variable lease expense	618	235
Total operating lease expense	$ 4,433	$ 3,769

Leases (Details 2) $ in Thousands	Mar. 31, 2022 USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Remaining in 2022	$ 11,285
2023	14,498
2024	14,836
2025	15,087
2026	15,540
2027	16,006
Thereafter	101,636
Total undiscounted lease payments	188,888
Less: imputed interest	(75,367)
Total lease liability	$ 113,521

Convertible Preferred Stock and Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2021	Nov. 30, 2016	Mar. 31, 2022	Dec. 31, 2019	Dec. 31, 2021	May 02, 2017
Convertible preferred stock
Preferred stock, par value (in dollars per share)			$ 0.001		$ 0.001
Employee And Non Employee Stock Option
Convertible preferred stock
Unrecognized compensation cost related to outstanding options			$ 58.1
Expected recognition weighted average period of unrecognized compensation cost			2 years 7 months 6 days
Restricted Stock Units (RSUs)
Convertible preferred stock
Expected recognition weighted average period of unrecognized compensation cost			3 years 4 months 24 days
Unrecognized compensation cost related to unvested restricted shares			$ 175.1
Pre-Funded Warrants
Convertible preferred stock
Number of shares to be purchased	257,310		257,310
Purchase price of prefunded warrants	$ 85.499
Exercise price of warrants	$ 0.001
Terms of exercise	The Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the Pre-Funded Warrant if the holder, together with its affiliates, would beneficially own more than 9.99% of the number of shares of the Company’s common stock outstanding immediately after giving effect to such exercise. A holder of Pre-Funded Warrants may increase or decrease this percentage not in excess of 19.99% by providing at least 61 days’ prior notice to the Company
Maximum percentage of common stock ownership together with affiliates allowable after exercise of prefunded warrants	9.99%
Maximum percentage of common stock ownership after change upon notice	19.99%
Common Stock
Convertible preferred stock
Conversion of preferred shares to common stock				125,000
Non-Voting Class A Preferred Stock \| Redmile Group, LLC and Affiliates
Convertible preferred stock
Percentage of common stock ownership upon preferred stock conversion		19.99%
Terms of conversion			The Class A Preferred were purchased exclusively by entities affiliated with Redmile Group, LLC (collectively, Redmile). The terms of the CoD prohibited Redmile from converting the Class A Preferred into shares of the Company’s common stock if, as a result of conversion, Redmile, together with its affiliates, would own more than 9.99% of the Company’s common stock then issued and outstanding (the Redmile Percentage Limitation), which percentage could change at Redmile’s election upon 61 days’ notice to the Company to (i) any other number less than or equal to 19.99% or (ii) subject to approval of the Company’s stockholders to the extent required in accordance with the Nasdaq Global Market rules, any number in excess of 19.99%. On May 2, 2017, the Company’s stockholders approved the issuance of up to an aggregate of 14,097,745 shares of common stock upon the conversion of the outstanding shares of Class A Preferred. As a result, Redmile has the right to increase the Redmile Percentage Limitation to any percentage in excess of 19.99% at its election.
Non-Voting Class A Preferred Stock \| Maximum
Convertible preferred stock
Number of shares to be issued upon conversion						14,097,745
Non-Voting Class A Preferred Stock \| Maximum \| Redmile Group, LLC and Affiliates
Convertible preferred stock
Percentage of common stock ownership upon preferred stock conversion		9.99%
Preferred shares converted into common stock percentage of ownership change upon notice		19.99%
Class A Convertible Preferred Shares
Convertible preferred stock
Preferred stock, issued shares			2,794,549		2,794,549
Conversion of preferred shares to common stock				(25,000)
November 2016 Placement \| Common Stock
Convertible preferred stock
Share issue price (in dollars per share)		$ 2.66
Common stock issued		7,236,837
November 2016 Placement \| Non-Voting Class A Preferred Stock
Convertible preferred stock
Preferred stock, issued shares		2,819,549
Share issue price (in dollars per share)		$ 13.30
Number of shares to be issued upon conversion		5
Preferred stock, par value (in dollars per share)		$ 0.001
Conversion price		$ 2.66

Convertible Preferred Stock and Stockholders' Equity (Details 2) - Employee And Non Employee Stock Option	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Number of Options
Balance at the beginning of the period \| shares	7,708,263
Granted \| shares	671,420
Exercised \| shares	(398,415)
Cancelled \| shares	(51,924)
Balance at the end of the period \| shares	7,929,344
Weighted-Average Price
Balance at the beginning of the period \| $ / shares	$ 20.43
Granted \| $ / shares	39.87
Exercised \| $ / shares	7.56
Cancelled \| $ / shares	33.61
Balance at the end of the period \| $ / shares	$ 22.63

Convertible Preferred Stock and Stockholders' Equity (Details 3) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Number of Restricted Stock Units
Balance at the beginning of the period \| shares	4,008,832
Granted \| shares	2,293,106
Vested \| shares	(412,707)
Cancelled \| shares	(98,518)
Balance at the end of the period \| shares	5,790,713
Weighted-Average Grant Date Fair Value per Share
Balance at the beginning of the period \| $ / shares	$ 58.60
Granted \| $ / shares	40.49
Vested \| $ / shares	45.87
Cancelled \| $ / shares	56.29
Balance at the end of the period \| $ / shares	$ 52.54

Convertible Preferred Stock and Stockholders' Equity (Details 4) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Convertible preferred stock
Total stock-based compensation expense	$ 19,331	$ 12,976
Research And Development
Convertible preferred stock
Total stock-based compensation expense	12,694	8,522
General And Administrative
Convertible preferred stock
Total stock-based compensation expense	$ 6,637	$ 4,454

Convertible Preferred Stock and Stockholders' Equity (Details 5) - Employee And Non Employee Stock Option	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Weighted-average assumptions to determine fair value of stock options
Risk-free interest rate	1.60%	0.40%
Expected volatility	75.80%	76.50%
Expected term (in years)	5 years 7 months 6 days	5 years 1 month 6 days
Expected dividend yield	0.00%	0.00%

Convertible Preferred Stock and Stockholders' Equity (Details 6) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Class Of Stock [Line Items]
Balance	$ 678,838	$ 384,445
Exercise of stock options, net of issuance costs	3,001	5,648
Issuance of common stock upon vesting of restricted stock units	1
Stock-based compensation	19,331	12,976
Public offering of common stock and issuance of pre-funded warrants, net of issuance costs		432,445
Unrealized gain (loss) on investments	(2,088)	(330)
Net loss	(65,690)	(45,089)
Balance	$ 633,393	$ 790,095
Class A Convertible Preferred Shares
Class Of Stock [Line Items]
Balance (in shares)	2,794,549	2,794,549
Balance (in shares)	2,794,549	2,794,549
Preferred Stock \| Class A Convertible Preferred Shares
Class Of Stock [Line Items]
Balance	$ 3	$ 3
Balance	3	3
Common Stock
Class Of Stock [Line Items]
Balance	$ 96	$ 88
Balance (in shares)	95,726,962	87,722,237
Exercise of stock options, net of issuance costs		$ 1
Exercise of stock options, net of issuance costs (in shares)	398,415	613,015
Issuance of common stock upon vesting of restricted stock units	$ 1
Issuance of common stock upon vesting of restricted stock units (in shares)	412,707	430,620
Public offering of common stock and issuance of pre-funded warrants, net of issuance costs		$ 5
Public offering of common stock and issuance of pre-funded warrants, net of issuance costs(in shares)		5,122,807
Balance	$ 97	$ 94
Balance (in shares)	96,538,084	93,888,679
Additional Paid In Capital
Class Of Stock [Line Items]
Balance	$ 1,448,584	$ 941,216
Exercise of stock options, net of issuance costs	3,001	5,647
Stock-based compensation	19,331	12,976
Public offering of common stock and issuance of pre-funded warrants, net of issuance costs		432,440
Balance	1,470,916	1,392,279
Accumulated Other Comprehensive Gain (Loss)
Class Of Stock [Line Items]
Balance	762	70
Unrealized gain (loss) on investments	2,088	330
Balance	(2,850)	(260)
Accumulated Deficit
Class Of Stock [Line Items]
Balance	(769,083)	(556,932)
Net loss	65,690	(45,089)
Balance	$ (834,773)	$ (602,021)

Subsequent Events (Additional Information) (Details) $ in Millions	1 Months Ended
	Apr. 30, 2022 USD ($)
Subsequent Event [Member] \| Janssen Agreement
Debt Instrument [Line Items]
Milestone receivable due	$ 3.0