0001564590-22-010539 | 10-K | XBRL Viewer

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Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 253,029	$ 124,806
Marketable securities	297,967	253,458
Prepaid expenses and other current assets	7,105	6,203
Total current assets	558,101	384,467
Long-term marketable securities	195,881	33,731
Property and equipment, net	65,464	46,775
Operating lease right-of-use assets	96,320	63,168
Restricted cash	8,819	2,143
Intangible asset	59,195	59,195
Goodwill	140,627	140,627
Other non-current assets	5,000	190
TOTAL ASSETS	1,129,407	730,296
Current liabilities:
Accounts payable	2,219	2,253
Accrued compensation	21,131	16,020
Accrued expenses and other current liabilities	10,344	9,466
Operating lease liabilities	9,159	3,712
Contingent consideration	51,382
Success payment liabilities	5,000
Total current liabilities	99,235	31,451
Operating lease liabilities, net of current portion	101,784	68,197
Contingent consideration, net of current portion	102,361	121,901
Success payment liabilities, net of current portion	97,525	76,494
Other non-current liabilities		540
Total liabilities	400,905	298,583
Commitments and contingencies (Note 9)
Convertible preferred stock, $0.0001 par value; zero and 537,786 shares authorized as of December 31, 2021 and 2020, respectively; zero and 134,113 shares issued and outstanding as of December 31, 2021 and 2020, respectively		852,897
Stockholders' equity (deficit):
Preferred stock, $0.0001 par value; 50,000 and zero shares authorized as of December 31, 2021 and 2020, respectively; zero shares issued and outstanding as of December 31, 2021 and 2020
Common stock, $0.0001 par value; 750,000 and 707,000 shares authorized as of December 31, 2021 and 2020, respectively; 184,929 and 16,170 shares issued and outstanding as of December 31, 2021 and 2020, respectively	18	2
Additional paid-in capital	1,515,210	8,216
Accumulated other comprehensive income (loss)	(1,366)	30
Accumulated deficit	(785,360)	(429,432)
Total stockholders' equity (deficit)	728,502	(421,184)
TOTAL LIABILITIES, CONVERTIBLE PREFERRED STOCK, AND STOCKHOLDERS' EQUITY (DEFICIT)	$ 1,129,407	$ 730,296

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	0	537,786,000
Convertible preferred stock, shares issued	0	134,113,000
Convertible preferred stock, shares outstanding	0	134,113,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	50,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	750,000,000	707,000,000
Common stock, shares issued	184,929,000	16,170,000
Common stock, shares outstanding	184,929,000	16,170,000

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 248,626	$ 132,944	$ 99,591
Research and development related success payments and contingent consideration	57,873	124,935	19,784
General and administrative	50,410	28,270	21,777
Total operating expenses	356,909	286,149	141,152
Loss from operations	(356,909)	(286,149)	(141,152)
Interest income, net	676	747	2,856
Other income (expense), net	305	97	(29)
Loss before income taxes	(355,928)	(285,305)	(138,325)
Benefit from income taxes			7,547
Net loss	$ (355,928)	$ (285,305)	$ (130,778)
Net loss per common share - basic and diluted	$ (2.14)	$ (21.92)	$ (26.68)
Weighted-average number of common shares - basic and diluted	166,433	13,014	4,903

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (355,928)	$ (285,305)	$ (130,778)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on marketable securities, net	(1,396)	4	26
Total comprehensive loss	$ (357,324)	$ (285,301)	$ (130,752)

- Definition

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

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+ Details

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Series A-2 Convertible Preferred Stock	Series B Convertible Preferred Stock	Convertible Preferred Stock	IPO	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Common Stock IPO	Additional Paid-in Capital	Additional Paid-in Capital IPO	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment
Beginning balance at Dec. 31, 2018	$ (13,188)					$ (102)			$ 59			$ (13,247)	$ (102)
Beginning balance (in shares) at Dec. 31, 2018				11,463
Beginning balance at Dec. 31, 2018				$ 45,721
Beginning balance (in shares) at Dec. 31, 2018							1,577
Accounting Standards Update [Extensible Enumeration]	us-gaap:AccountingStandardsUpdate201602Member
Issuance of convertible preferred stock, net of issuance costs		$ 223,739
Issuance of convertible preferred stock, net of issuance costs, (in shares)		56,003
Issuance of convertible preferred stock for acquisition, non-cash		$ 135,971
Issuance of convertible preferred stock for acquisition, non-cash (in shares)		36,442
Issuance of convertible preferred stock in connection with license agreements		$ 11,928
Issuance of convertible preferred stock in connection with license agreements (in shares)		2,982
Vesting of restricted stock	$ 1						$ 1
Vesting of restricted stock (in shares)							8,425
Stock-based compensation	1,498								1,498
Exercise of stock options	1								1
Exercise of stock options (in shares)							1
Unrealized gain on marketable securities, net	26										$ 26
Net loss	(130,778)											(130,778)
Ending balance at Dec. 31, 2019	(142,542)						$ 1		1,558		26	(144,127)
Ending balance (in shares) at Dec. 31, 2019				106,890
Ending balance at Dec. 31, 2019				$ 417,359
Ending balance (in shares) at Dec. 31, 2019							10,003
Issuance of convertible preferred stock, net of issuance costs	435,538
Issuance of convertible preferred stock, net of issuance costs, (in shares)			27,223
Issuance of common stock in connection with license agreement	680								680
Issuance of common stock in connection with license agreement (in shares)							100
Vesting of restricted stock	1						$ 1
Stock-based compensation	5,829								5,829
Exercise of stock options	149								149
Exercise of stock options (in shares)							103
Unrealized gain on marketable securities, net	4										4
Net loss	(285,305)											(285,305)
Ending balance at Dec. 31, 2020	$ (421,184)						$ 2		8,216		30	(429,432)
Ending balance (in shares) at Dec. 31, 2020	134,113			134,113
Ending balance at Dec. 31, 2020	$ 852,897			$ 852,897
Ending balance (in shares) at Dec. 31, 2020	16,170						16,170
Vesting of restricted stock, (in Shares)							5,964
Conversion of convertible preferred stock into common stock upon initial public offering	$ 852,897						$ 13		852,884
Conversion of convertible preferred stock into common stock, upon initial public offering (in shares)	(134,113)
Conversion of convertible preferred stock into common stock, upon initial public offering	$ (852,897)
Conversion of convertible preferred stock into common stock, upon initial public offering (in shares)							134,113
Issuance of common stock in initial public offering, net of offering costs					$ 626,405			$ 3		$ 626,402
Issuance of common stock in initial public offering, net of offering costs (in shares)								27,025
Vesting of restricted stock (in shares)							5,916
Issuance of common stock related to employee stock purchase plan	2,179								2,179
Issuance of common stock related to employee stock purchase plan, Shares							119
Stock-based compensation	22,362								22,362
Exercise of stock options	$ 3,167								3,167
Exercise of stock options (in shares)	1,586						1,586
Unrealized gain on marketable securities, net	$ (1,396)										(1,396)
Net loss	(355,928)											(355,928)
Ending balance at Dec. 31, 2021	$ 728,502						$ 18		$ 1,515,210		$ (1,366)	$ (785,360)
Ending balance (in shares) at Dec. 31, 2021	0
Ending balance (in shares) at Dec. 31, 2021	184,929						184,929

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
IPO
Issuance of common stock in initial public offering, net of offering costs	$ 49,220
Series B Convertible Preferred Stock
Convertible preferred stock, issuance costs		$ 33
Series A-2 Convertible Preferred Stock
Convertible preferred stock, issuance costs			$ 300

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES:
Net loss	$ (355,928)	$ (285,305)	$ (130,778)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	11,070	5,921	1,826
Deferred income tax			(7,547)
Stock-based compensation expense	22,362	5,828	1,497
Change in the estimated fair value of contingent consideration	31,842	52,793	17,860
Change in the estimated fair value of success payment liabilities	26,031	72,142	1,924
Non-cash expense in connection with license agreement and asset acquisition		1,530	17,685
Non-cash expense for operating lease right-of-use assets	6,844	4,250	2,095
Other non-cash items, net	(3,076)	(1,297)	(592)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(861)	(1,436)	(4,300)
Operating lease right-of-use assets and liabilities	5,088	91	5,697
Accounts payable	(266)	1,982	(421)
Accrued expenses and other liabilities	5,840	5,519	9,536
Net cash used in operating activities	(251,054)	(137,982)	(85,518)
INVESTING ACTIVITIES:
Purchases of marketable securities	(491,387)	(387,432)	(141,519)
Proceeds from sales and maturities of marketable securities	280,025	158,741	82,977
Purchases of property and equipment	(29,862)	(23,872)	(26,124)
Acquisitions, net of cash acquired			(3,195)
Other investing activities	(4,574)
Net cash used in investing activities	(245,798)	(252,563)	(87,861)
FINANCING ACTIVITIES:
Proceeds from initial public offering, net of issuance costs	626,405
Proceeds from issuance of convertible preferred stock, net of issuance costs		435,538	223,739
Proceeds from employee stock purchase plan and exercise of stock options, net	5,346	149	1
Net cash provided by financing activities	631,751	435,687	223,740
Net increase in cash, cash equivalents, and restricted cash	134,899	45,142	50,361
Cash, cash equivalents, and restricted cash at beginning of period	126,949	81,807	31,446
Cash, cash equivalents, and restricted cash at end of period	261,848	126,949	81,807
SUPPLEMENTAL CASH FLOW INFORMATION:
Operating lease right-of-use assets obtained in exchange for lease obligations	39,996	26,521	48,863
Cash received for amounts related to tenant improvement allowances	5,445	91	5,697
Purchases of property and equipment included in accounts payable and accrued liabilities	$ 3,015	$ 3,140	2,495
Issuance of convertible preferred stock for acquisition			$ 135,971

Organization

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Organization

1. Organization

Sana Biotechnology, Inc. (the Company or Sana) is a biotechnology company focusing on utilizing engineered cells as medicines. The Company’s operations to date have included identifying and developing potential product candidates, executing preclinical studies, establishing manufacturing capabilities, acquiring technology, organizing and staffing the Company, business planning, establishing the Company’s intellectual property portfolio, raising capital, and providing general and administrative support for these operations.

Reverse stock split

In January 2021, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-4 reverse stock split of shares of the Company’s common and convertible preferred stock, which was effected on January 27, 2021. The par value per share and authorized shares of common and convertible preferred stock were not adjusted as a result of the reverse stock split. All share and per share information included in the accompanying consolidated financial statements has been adjusted to reflect the reverse stock split.

Initial public offering

In February 2021, the Company successfully completed its initial public offering (IPO) of its common stock. In connection with its IPO, the Company issued 27.0 million shares of its common stock, including 3.5 million shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a price of $25.00 per share, and received $626.4 million in net proceeds, after deducting underwriting discounts and commissions of $45.2 million and offering expenses of $4.0 million. At the closing of the IPO, 134.1 million shares of convertible preferred stock then outstanding were automatically converted into shares of common stock. The related carrying value of the converted preferred stock of $852.9 million was reclassified to common stock and additional paid in-capital.

Need for additional capital

The Company is subject to a number of risks and uncertainties similar to other biotechnology companies in the development stage, including, but not limited to, those related to the need to obtain adequate additional funding, possible failure of preclinical testing or clinical trials, the need to obtain marketing approval for its product candidates, building out internal and external manufacturing capabilities, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of the Company’s products, the need to protect the Company’s intellectual property and proprietary technology, and the need to attract and retain key scientific and management personnel. If the Company does not successfully commercialize or partner any of its product candidates, it will be unable to generate product revenue or achieve profitability. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations with the proceeds from additional equity or debt financings or capital obtained in connection with strategic collaborations or licensing or other arrangements. In the event that additional financing is required, the Company may not be able to raise it on terms acceptable to it or at all.

The Company has incurred operating losses each year since inception and expects such losses to continue for the foreseeable future. As of December 31, 2021, the Company had cash, cash equivalents, and marketable securities of $746.9 million, and an accumulated deficit of $785.4 million, which includes non-cash charges related to the revaluation of the success payment liabilities and contingent consideration of $100.1 million and $102.5 million, respectively.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of significant accounting policies

Basis of presentation

The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. The Company’s consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (GAAP). Certain prior period amounts have been reclassified to conform to current period presentation.

Use of estimates

The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates. The most significant estimates in the Company’s consolidated financial statements relate to success payment liabilities, contingent consideration, business combinations, accrued expenses, operating lease right of use assets and liabilities, and the valuation of stock options.

Cash and cash equivalents

Cash and cash equivalents include cash and highly liquid investments with original maturities of three months or less at acquisition. Cash equivalents include investments in money market funds with commercial banks and financial institutions and are stated at fair value.

Marketable securities

Marketable securities are classified as available-for-sale debt securities and are carried at fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Investments in securities with maturities of less than one year, or those for which management intends to use to fund current operations, are included in current assets. Unrealized gains and losses that are deemed to be temporary in nature are reported as a component of accumulated comprehensive income (loss). Amortization, accretion, and dividends are included in other income (expense), net on the consolidated statement of operations. The cost of securities sold is based on the specific-identification method. Each reporting period, the Company evaluates whether declines in fair value below carrying value are due to expected credit losses, as well as the Company’s ability and intent to hold the investment until a forecasted recovery occurs. Expected credit losses are recorded as an allowance through other income (expense), net.

Concentrations of credit risk and off-balance sheet risk

The Company maintains its cash, cash equivalents, and marketable securities with high quality, accredited financial institutions. These amounts, at times, may exceed federally insured limits. The Company has not experienced any credit losses in such accounts and does not believe it is exposed to significant risk on these funds. The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts, or other hedging arrangements.

Fair value measurement

The Company accounts for certain assets and liabilities at fair value and is required to disclose information that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The hierarchy applies only to the valuation inputs used to determine the reported fair value of the investments and is not a measure of the investment credit quality. The hierarchy defines three levels of valuation inputs:

Level 1 – Quoted prices in active markets for identical assets or liabilities.

Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

The Company’s financial instruments include cash and cash equivalents, short- and long-term marketable securities, accounts payable, contingent consideration, success payment liabilities, and other accrued liabilities. The carrying amounts of cash, cash equivalents, accounts payable, and accrued liabilities approximate fair value due to the short-term nature of these instruments. To the extent the valuation of financial instruments is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. See Note 6, Fair value measurements for more information on how the Company determines fair value.

Property and equipment, net

Property and equipment are stated at cost, net of accumulated depreciation. Depreciation of property and equipment is computed using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are depreciated over the lesser of their useful lives or the remaining life of the lease. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation and amortization are removed from the balance sheet and the

resulting gain or loss is recorded in other income (expense), net in the period realized. Maintenance and repairs are expensed as incurred.

Impairment of long-lived assets

The Company reviews the carrying value and estimated lives of its long-lived assets whenever events or circumstances indicate the carrying values may not be recoverable. Should an impairment exist, the impairment loss would be measured based on the excess of the asset’s carrying amount over its fair value. The Company has not recognized any impairment losses since inception.

Acquisitions

The Company accounts for business combinations using the acquisition method of accounting, which requires the assets acquired, including in-process research and development (IPR&D), and liabilities assumed be recorded at fair value as of the acquisition date. Any excess of the purchase price over the fair value of net assets acquired is recorded as goodwill. The determination of the estimated fair value of these items requires significant estimates and assumptions. Transaction costs associated with business combinations are recorded in general and administrative expense as they are incurred.

If the Company determines the acquisition does not meet the definition of a business combination under the acquisition method of accounting, the transaction is accounted for as an asset acquisition. In an asset acquisition, up-front payments allocated to IPR&D are recorded in research and development expense if it is determined that there is no alternative future use, and subsequent milestone payments are recorded in research and development expense when achieved.

Goodwill and intangible assets

Goodwill represents the excess of the purchase price over the estimated fair value of the identifiable assets acquired and liabilities assumed in a business combination. The Company evaluates goodwill for impairment annually or when a triggering event occurs that could indicate a potential impairment. The evaluation for impairment includes assessing qualitative factors or performing a quantitative analysis to determine whether it is more-likely-than-not that the fair value of net assets is below the carrying amount. As of December 31, 2021, the Company had goodwill of $140.6 million related to the 2019 acquisition of Cobalt, which represents the excess of the purchase price over the estimated fair value of the net assets acquired. There have been no impairments of goodwill since the acquisition.

Intangible assets acquired in a business combination are recognized separately from goodwill and are initially recognized at fair value at the acquisition date. The fair value of the IPR&D is estimated using the replacement cost method. Under this method, the Company estimates the cost to recreate the technology and derive an estimated value to develop the technology. IPR&D assets are required to be classified as indefinite-lived assets and are not amortized until they become finite-lived assets upon the successful completion of the associated research and development technology. At that time, the useful life of the asset will be determined, and amortization will begin. If the associated research and development technology is abandoned, the related IPR&D asset will be written off and an impairment charge recorded. Intangible assets are reviewed for impairment at least annually or when a triggering event occurs that could indicate a potential impairment. As of December 31, 2021, there was no amortization or impairments of the intangible asset.

Contingent consideration from business combinations

Contingent consideration from a business combination is recorded at fair value on the acquisition date and remeasured at each subsequent reporting period with changes in fair value recognized in research and development related success payments and contingent consideration. Changes in fair values reflect changes to the Company’s assumptions regarding probabilities of successful achievement of related milestones, the timing in which the milestones are expected to be achieved, and the discount rate used to estimate the fair value of the obligation.

Success payments

The Company granted rights to a success payment to Cobalt Biomedicine, Inc. (Cobalt) pursuant to the terms of its acquisition agreement and to the President and Fellows of Harvard College (Harvard) pursuant to the terms of its exclusive license agreement. See Note 3, Acquisitions and Note 4, License and collaboration agreements for more details on the success payments.

The success payments are accounted for under Accounting Standards Codification (ASC) 815, Derivatives and Hedging. The success payment related to the acquisition of Cobalt (Cobalt Success Payment) was recorded as a liability on the consolidated balance sheet at fair value on the acquisition date and is remeasured at each subsequent reporting period, with changes in fair value recognized

in research and development related success payments and contingent consideration. For the success payments to Harvard (Harvard Success Payments), both the initial value and subsequent changes in fair value are recorded in research and development related success payments and contingent consideration.

To determine the estimated fair value of the success payment liabilities, the Company uses a Monte Carlo simulation methodology, which models the value of the liabilities based on several key assumptions, including the remaining terms of the success payments, risk-free interest rate, estimated number and timing of valuation measurement dates on the basis of which payments may be triggered, and expected volatility of the Company’s common stock. Expected volatility is estimated using the volatility of peer companies for a period of time commensurate with the remaining terms of the success payments. Additionally, prior to the IPO, the Cobalt Success Payment liability incorporated the estimated future value of the Company implied by the estimated per share value of the Company’s Series B convertible preferred stock at issuance, and the Harvard Success Payment liability incorporated the estimated per share value of the Company’s Series A convertible preferred stock. Concurrent with the closing of the Company’s IPO in February 2021, the Company’s Series A and Series B convertible preferred stock converted into common stock. Subsequent to the IPO, the computation of the estimated fair value of the Cobalt Success Payment liability incorporates the market capitalization of the Company at the end of each reporting period, and the computation of the estimated fair value of the Harvard Success Payments incorporates the per share fair market value of the Company’s common stock at the end of each reporting period.

Leases

At the inception of the arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present in the arrangement. Lease liabilities represent an obligation to make payments arising from a lease and are measured at the present value of the remaining future lease payments over the term of the lease. The present value of the lease payments is determined using an incremental borrowing rate (IBR), which reflects the fixed rate at which the Company could borrow the amount of the lease payments, on a collateralized basis, for a similar term and economic environment. The lease terms may include the impact of options to extend or terminate the lease when it is reasonably certain that the Company will exercise the option. Assumptions made by the Company at the commencement date are re-evaluated upon the occurrence of certain events, including a lease modification. When a lease modification results in a separate contract, it is accounted for in the same manner as a new lease. Right-of-use (ROU) assets represent the right to use the underlying asset identified in the lease for the term of the agreement. The calculation of the ROU asset incorporates the value of the lease liability and excludes any lease incentives received and initial direct costs incurred.

The Company’s lease portfolio consists of operating leases related to its facilities for office, laboratory, and manufacturing space. The Company does not have any financing leases. Leases with a term of 12 months or less are considered short-term and do not require recognition on the balance sheet, and payments associated with short-term leases are expensed as incurred. Rent expense for operating leases is recognized on a straight-line basis over the lease term.

Claims and contingencies

From time to time, the Company may become involved in litigation and proceedings relating to claims arising from the ordinary course of business. The Company accrues a liability if the likelihood of an adverse outcome is probable, and the amount can be reasonably estimated. If the likelihood of an adverse outcome is only reasonably possible, or if an adverse outcome is probable, but an estimate is not determinable, the Company provides disclosure of the material claim or contingency.

Convertible preferred stock

The carrying value of the Company’s Series A-1, Series A-2, and Series B convertible preferred stock was adjusted to reflect dividends if and when declared by the Company’s board of directors. No dividends have been declared by the board of directors since inception. The Company classified its convertible preferred stock outside of permanent equity, as the redemption of such stock was not solely under the control of the Company. The Company recorded its convertible preferred stock at the issuance price on the dates of issuance, net of issuance costs. Concurrent with the closing of the Company’s IPO in February 2021, all of the Company’s convertible preferred stock converted into common stock.

Stock-based compensation

The Company recognizes compensation costs related to restricted stock awards (RSAs), restricted stock units (RSUs), and stock options granted to employees and nonemployees based on the estimated fair value of the awards on the date of grant and recognizes expense on a straight-line basis over the requisite service period, which is generally the vesting period of the award. Forfeitures are recognized as they occur. For RSAs and RSUs, the fair value of the Company’s common stock is used to determine the resulting

stock-based compensation expense. The fair value of stock options is estimated on the date of grant using a Black-Scholes option pricing model which requires management to apply judgment and make estimates, including:

•

Fair Value of Common Stock—The fair value of common stock is based on the closing price as reported on The Nasdaq Global Select Market on the date of grant.

•

Expected Term—The expected term represents the period that a stock-based award is expected to be outstanding. The Company uses the simplified method to determine the expected term, which is based on the average of the time-to-vesting and the contractual life of the option.

•

Expected Volatility— Due to the Company’s limited operating history and lack of company-specific historical and implied volatility data, the expected volatility is estimated based on the average historical volatilities of common stock of comparable publicly traded entities over a period of time commensurate with the expected term of the stock option grants. The comparable companies are chosen based on their size, stage in the product development cycle, or area of specialty. The Company will continue to apply this process until sufficient historical information regarding the volatility of its own stock price becomes available.

•

Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for zero-coupon U.S. Treasury notes with maturities approximately equal to the expected term of the awards.

•

Expected Dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Research and development expense

The Company records expense for research and development costs as incurred. Nonrefundable, advance payments for goods or contracts for services are deferred, and expense is recognized in the period in which the goods are received or the services are rendered. Research and development expense consist of personnel-related costs, including salaries, benefits, and non-cash stock-based compensation, external research and development expenses incurred under arrangements with third parties, costs for laboratory supplies, costs to acquire and license technologies aligned with our goal of translating engineered cells to medicines, facility and other allocated expenses, including rent, depreciation, and allocated overhead costs, and other research and development expenses.

Research and development related success payment and contingent consideration

Research and development related success payments and contingent consideration include the change in the estimated fair value of the Cobalt Success Payment and Harvard Success Payment liabilities and Cobalt Contingent Consideration. Research and development expense related to the success payment liabilities and contingent consideration is unpredictable and may vary significantly from quarter-to-quarter and year-to-year due to changes in the assumptions used in the calculations.

General and administrative expenses

General and administrative expenses consist of personnel costs, including salaries, benefits, and non-cash stock-based compensation, for employees in finance, legal, executive, human resources, information technology, and other administrative functions, legal and consulting fees, recruiting costs, and facility costs not otherwise included in research and development expenses. Legal fees include those related to corporate and patent matters.

Income taxes

The Company determines its deferred tax assets and liabilities based on the differences between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded when it is more likely than not that the deferred tax asset will not be recovered. The Company applies judgment in the determination of the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The Company recognizes any material interest and penalties related to unrecognized tax benefits in income tax expense.

The Company is required to file income tax returns in the United States (U.S.) federal jurisdiction, and other state and local jurisdictions. The Company is generally subject to examination by U.S. federal and local income tax authorities for all tax years in which the loss carryforward is available. The Company is currently not under examination by the Internal Revenue Service or other jurisdictions for any tax years.

Segments

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment.

JOBS Act accounting election

The Company is an emerging growth company (EGC), as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act). Under the JOBS Act, an EGC can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies; however, the Company may adopt new or revised accounting standards early if the standard allows for early adoption.

In addition, the Company will utilize other exemptions and reduced reporting requirements provided to EGCs by the JOBS Act. Subject to certain conditions set forth in the JOBS Act, an EGC is not required to, among other things, (i) provide an auditor’s attestation report on the Company’s system of internal controls over financial reporting pursuant to Section 404(b) of the Sarbanes-Oxley Act of 2002, (ii) provide all of the compensation disclosure that may be required of non-emerging growth public companies under the Dodd-Frank Wall Street Reform and Consumer Protection Act, (iii) comply with any requirement that may be adopted by the Public Company Accounting Oversight Board regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements (auditor discussion and analysis), or (iv) disclose certain executive compensation-related items, such as the correlation between executive compensation and performance and comparisons of the chief executive officer’s compensation to median employee compensation.

Recent accounting pronouncements

Recently adopted

In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-13, Financial Instruments—Credit Losses (Topic 362): Measurement of Credit Losses on Financial Statements (ASU 2016-13). The new standard requires that expected credit losses relating to financial assets measured on an amortized cost basis and available-for-sale debt securities be recorded through an allowance for credit losses. It also limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which the carrying value exceeds fair value and also requires the reversal of previously recognized credit losses if fair value increases. The targeted transition relief standard allows companies an option to irrevocably elect the fair value option of ASC 825-10, Financial Instruments-Overall, applied on an instrument-by-instrument basis for eligible instruments. The Company adopted ASU 2016-13 effective January 1, 2021. The adoption of the guidance did not have a material impact on the Company’s consolidated financial statements and related disclosures, and no allowance for losses on available-for-sale debt securities attributable to credit risk has been recorded.

Not yet adopted

ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment

In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (ASU 2017-04). To address concerns over the cost and complexity of the two-step goodwill impairment test, the amendments in this ASU remove the second step of the test. An entity will instead apply a one-step quantitative test and record the amount of goodwill impairment as the excess of a reporting unit’s carrying amount over its fair value, not to exceed the total amount of goodwill allocated to the reporting unit. The new guidance does not amend the optional qualitative assessment of goodwill impairment. The new standard will be effective beginning January 1, 2023. The adoption of ASU 2017-04 is not expected to have a material impact on the Company’s consolidated financial statements.

Acquisitions

12 Months Ended

Dec. 31, 2021

Business Combinations [Abstract]

Acquisitions

3. Acquisitions

Oscine Corp.

In September 2020, the Company entered into a stock purchase agreement to acquire 100% of the outstanding equity of Oscine Corp. (Oscine), a privately-held early-stage biotechnology company whose primary asset was IPR&D related to its ex vivo glial progenitor cell technology focused on brain disorders. The Company acquired Oscine for a purchase price of $8.5 million, of which $7.6 million was an upfront cash payment, and $0.9 million was set aside to satisfy certain general representations and warranties set forth in the stock purchase agreement (Oscine Holdback Amount). The Oscine Holdback Amount was paid in full in December 2021.

The Company evaluated the acquisition and determined the screen test, as permitted under ASC 805, Business Combinations, was met, as the $8.5 million purchase price represented consideration for a single identifiable asset related to the technology. The Company concluded the asset acquired did not meet the definition of a business, and the asset had no alternative future use. The transaction was accounted for as an asset acquisition, and the purchase price of $8.5 million was recorded in research and development expense for the year ended December 31, 2020.

The Company is required to make up to an aggregate of $225.8 million in future milestone payments upon the achievement of certain development and commercial milestones.

Cytocardia, Inc.

In November 2019, the Company acquired 100% of the outstanding equity of Cytocardia, Inc. (Cytocardia), a privately-held early-stage biotechnology company whose primary asset was IPR&D related to its ex vivo cell engineering technology focused on replacement of damaged heart cells. The Company acquired Cytocardia for a purchase price of $8.0 million, of which $6.8 million was an upfront cash payment, and $1.2 million was set aside to satisfy certain general representations and warranties set forth in the stock purchase agreement (Cytocardia Holdback Amount). The Cytocardia Holdback Amount was paid in full in February 2021.

The Company evaluated the acquisition and determined the screen test, as permitted under ASC 805, Business Combinations, was met, as the $8.0 million purchase price represented consideration for a single identifiable asset related to the technology. The Company concluded the asset acquired did not meet the accounting definition of a business, and the asset had no alternative future use. The transaction was accounted for as an asset acquisition, and the purchase price of $8.0 million was recorded in research and development expense for the year ended December 31, 2019.

The Company is required to make future milestone payments of up to an aggregate of $140.0 million upon the achievement of certain pre-specified development and commercial milestones.

Cobalt Biomedicine, Inc.

In February 2019, the Company acquired 100% of the outstanding equity in Cobalt, a privately-held early-stage biotechnology company developing a platform technology using its fusogen technology to specifically and consistently deliver various biological payloads to cells. The Company issued 36.4 million shares of its Series A-2 convertible preferred stock, valued at $136.0 million, in consideration for this transaction. Of the 36.4 million shares of Series A-2 convertible preferred stock issued, 12.1 million shares were restricted based on the achievement of a pre-specified development milestone, which was achieved in July 2019. Additionally, 0.7 million RSAs and 0.3 million RSUs were granted to former employees of Cobalt. Upon the closing of the Company’s IPO in February 2021, the Series A-2 convertible preferred stock issued in connection with the acquisition of Cobalt converted into common stock.

The Company accounted for the Cobalt acquisition as a business combination using the acquisition method of accounting. Under this method, the assets acquired and liabilities assumed are measured at their fair values as of the acquisition date. The elements of the purchase consideration are as follows (in thousands):

Series A-2 convertible preferred stock issued⁽¹⁾	$	97,178
First milestone - restricted Series A-2 convertible preferred stock⁽²⁾		38,769
Success payment⁽³⁾		2,428
Fair value of contingent consideration⁽⁴⁾		51,248
Other		66
Total consideration	$	189,689

(1)

The purchase consideration included 24.3 million shares of the Company’s Series A-2 convertible preferred stock. The value of the stock issued was $4.00 per share, equivalent to the purchase price per share of the Series A-2 convertible preferred stock financing that occurred in February 2019.

(2)

The Company concluded the value of the first milestone, to be paid in restricted shares of Series A-2 convertible preferred stock, met the definition of being indexed to common stock. The restricted Series A-2 convertible preferred shares were recorded in convertible preferred stock valued at $38.8 million based on the estimated probability and timing of the milestone achievement on the date of acquisition and are not subject to remeasurement upon achievement of the milestone. In July 2019, the first milestone was achieved, and the Company issued a total of 12.1 million shares of its Series A-2 convertible preferred stock.

(3)

The fair value of the success payment was determined using a Monte Carlo simulation methodology, which models the estimated fair value of the liability based on several key assumptions including the term of the success payment, expected volatility, risk-free interest rate, estimated number and timing of valuation measurement dates on the basis of which payment may be triggered, and the estimated future value of the Company implied by the estimated future per share value of the Company’s Series B convertible preferred stock at issuance.

(4)

The fair value of the contingent consideration was determined by calculating the probability-weighted value of the milestone payments based on the assessment of the likelihood and estimated timing that certain milestones would be achieved and using estimated discount rates ranging from 15.3% to 17.6%. The discount rate captures the credit risk associated with the payment of the contingent consideration when earned and due.

The allocation of the purchase price is based on the estimated fair value of the assets acquired and liabilities assumed as of the date of acquisition. The components of the purchase price allocation are as follows (in thousands):

Net working capital	$	(3,275	)
Property and equipment		689
Net liabilities assumed		(2,586	)
Deferred tax liability		(7,547	)
Acquired in-process research and development		59,195
Goodwill		140,627
Total consideration	$	189,689

As part of the Cobalt acquisition, the Company recorded an intangible asset of $59.2 million, which consists of IPR&D that is classified as indefinite-lived until the successful completion of the associated research and development technology, at which point it becomes a finite-lived asset and will be amortized over its estimated useful life. If the research and development technology is abandoned, an impairment charge will be recorded. The Company is actively developing the fusogen technology and, accordingly, the intangible asset is not complete. Amortization will begin when regulatory approval is obtained in a major market, typically either the United States or the European Union.

The Company recognized $140.6 million of goodwill as a result of the Cobalt acquisition, which is primarily attributable to the value the acquisition provides the Company by complementing the Company’s ex vivo portfolio with in vivo cell engineering technology and furthering the Company’s research in using engineered cells as medicines. The goodwill is not deductible for income tax purposes.

Pursuant to the terms and conditions in the Cobalt acquisition agreement, the Company has an obligation to pay to certain former Cobalt stockholders up to an aggregate of $500.0 million in contingent consideration (Cobalt Contingent Consideration) upon the achievement of certain pre-specified development milestones, and a success payment (Cobalt Success Payment) of up to $500.0 million, payable in cash or stock. The Cobalt Success Payment is payable if, at pre-determined valuation measurement dates, including the closing of the Company’s IPO, the Company’s market capitalization equals or exceeds $8.1 billion, and the Company is advancing a program based on the fusogen technology in a clinical trial pursuant to an investigational new drug application (IND), or has filed for, or received approval for, a biologics license application (BLA) or new drug application (NDA). The Cobalt Success Payment can be achieved over a maximum of 20 years from the date of the Cobalt acquisition, but this period could be shorter upon the occurrence of certain events. As of December 31, 2021, a Cobalt Success Payment had not been triggered.

In addition to our IPO, a valuation measurement date would be triggered upon a change of control of the Company if at least one Company product based on the fusogen technology is the subject of an active research program at the time of such change of control. If there is a change of control and the Company’s market capitalization is below $8.1 billion as of the date of the change of control,

the amount of the potential Cobalt Success Payment will decrease, and the amount of potential Cobalt Contingent Consideration will increase.

The following table sets forth various thresholds for the Company’s market capitalizations as of the date of a change of control and the resulting potential Cobalt Success Payment and additional potential Cobalt Contingent Consideration:

Sana market capitalization upon a change of control and resulting impact to Cobalt Success Payment and additional potential Cobalt Contingent Consideration	Cobalt Success Payment		Additional potential Cobalt Contingent Consideration
	(in millions)
Equal to or exceeds $8.1 billion	$	500	$	-
Equal to or exceeds $7.4 billion, but less than $8.1 billion		150		350
Equal to or exceeds $6.8 billion, but less than $7.4 billion		100		400
Less than $6.8 billion		-		500

The Cobalt Success Payment and Cobalt Contingent Consideration liabilities are carried at fair value with changes in fair value recognized in research and development related success payments and contingent consideration. As of December 31, 2021 and 2020, the estimated fair value of the Cobalt Success Payment liability was $88.3 million and $64.7 million, respectively, and was recorded in long-term liabilities in the consolidated balance sheets. As of December 31, 2021, the estimated fair value of the Cobalt Contingent Consideration was $153.7 million, of which $51.4 million was recorded in short-term liabilities and $102.3 million was recorded in long-term liabilities in the consolidated balance sheet. As of December 31, 2020, the estimated fair value of the Cobalt Contingent Consideration was $121.9 million and was recorded in long-term liabilities in the consolidated balance sheet. For the years ended December 31, 2021, 2020, and 2019 the Company recognized $23.6 million, $62.3 million, and an immaterial amount, respectively, in connection with the change in fair value of the Cobalt Success Payment, and $31.8 million, $52.8 million, and $17.9 million, respectively, in connection with the change in fair value of the Cobalt Contingent Consideration.

License and collaboration agreements

12 Months Ended

Dec. 31, 2021

License And Collaboration Agreements [Abstract]

License and Collaboration Agreements

4. License and collaboration agreements

Beam Therapeutics Inc.

In October 2021, the Company entered into an option and license agreement with Beam Therapeutics Inc. (Beam), pursuant to which the Company was granted a non-exclusive license to use Beam’s proprietary CRISPR Cas12b nuclease editing technology to research, develop, and commercialize engineered cell therapy products that (i) are directed to certain antigen targets, with respect to the Company’s allogeneic T cell programs, or (ii) comprise certain human cell types, with respect to the Company’s stem cell-derived programs. The Company made an upfront payment of $50.0 million to Beam, which was recorded in research and development expense for the year ended December 31, 2021. Additionally, under the terms of the agreement, the Company may be obligated to pay up to $65.0 million for each licensed product in specified developmental and commercial milestone payments and royalties on licensed products. At the time of the entry into the option and license agreement, a member of the Company’s board of directors was a beneficial owner of greater than 10% of the outstanding shares of Beam and is affiliated with a member of the board of directors of Beam.

President and Fellows of Harvard College

In March 2019, the Company entered into an exclusive license agreement with Harvard to access certain intellectual property for the development of hypoimmune cells. Under this agreement, the Company paid $3.0 million in cash and issued 2.2 million shares of its Series A-2 convertible preferred stock, valued at $4.00 per share, for total consideration of $12.0 million. The Company determined the licensed technology had no alternative future use and the $12.0 million was therefore recorded in research and development expense for the year ended December 31, 2019. Upon the closing of the Company’s IPO in February 2021, the Series A-2 convertible preferred stock issued in connection with the license agreement with Harvard converted into common stock.

In connection with this agreement, the Company agreed to pay Harvard a license payment of $6.0 million in cash contingent upon the closing of the Company’s Series B convertible preferred stock financing. This contingent license payment was accounted for as a derivative under ASC 815, Derivatives and Hedging, carried at fair value, and was revalued each reporting period, with changes recognized in research and development expense. As of December 31, 2019, the estimated fair value of the contingent license payment to Harvard was $4.6 million, and the Company recorded research and development expense of $1.4 million and $4.6 million, respectively, for the years ended December 31, 2020 and 2019. The Series B convertible preferred stock financing closed in June 2020, and the Company paid Harvard $6.0 million in cash.

Under the terms of the agreement, the Company may be required to pay up to an aggregate of $175.0 million in success payments to Harvard, payable in cash, based on increases in the fair value of the Company’s common stock. The potential Harvard Success Payments are based on multiples of increased value ranging from 5x to 40x, based on a comparison of the fair market value of

the Company’s common stock relative to the original issuance price of $4.00 per share at pre-determined valuation measurement dates, which include: the one year anniversary of the IPO, the date of the consummation of a merger, an asset sale, or the sale of the majority of the shares held by the Company’s Series A convertible preferred stockholders, and the last day of the term of the Harvard Success Payments. The first Harvard valuation measurement date occurred in February 2022 on the one-year anniversary of the IPO. The threshold was not met, and therefore no payment was made as of measurement date.

The aggregate amount of the Harvard Success Payments will not exceed an aggregate of $175.0 million, which payment amount would only occur upon a 40x increase in the fair value of the Company’s common stock based on a comparison of the fair market value of the Company’s common stock relative to the original issuance price of $4.00 per share. If a higher success payment tier is first met at the same time a lower tier is first met, both tiers will be owed. Any previous success payments made to Harvard would be credited against the success payment owed as of any valuation measurement date so that Harvard does not receive multiple success payments in connection with the same threshold. The Harvard Success Payments can be achieved over a maximum of 12 years from the effective date of the agreement. The following table summarizes the potential success payments and common stock price required for payment:

Multiple of Equity Value at Issuance	5x		10x		20x		30x		40x
Per share common stock price required for payment	$	20.00	$	40.00	$	80.00	$	120.00	$	160.00
Success payment(s) (in millions)	$	5.0	$	15.0	$	30.0	$	50.0	$	75.0

The Harvard Success Payment liabilities are carried at fair value, with the initial value and changes in fair value recognized in the consolidated statements of operations in research and development related success payments and contingent consideration. As of December 31, 2021 and 2020, the estimated fair value of the Harvard Success Payment liability was $14.2 million and $11.8 million, respectively, of which $5.0 million and $0, respectively, were recorded in short-term liabilities, and $9.2 million and $11.8 million, respectively, were recorded in long-term liabilities in the consolidated balance sheet. In connection with the change in the estimated fair value of the Harvard Success Payment liability the Company recognized expenses of $2.4 million, $9.9 million, and $1.9 million, respectively, for the years ended December 31, 2021, 2020, and 2019.

Restricted Cash

12 Months Ended

Dec. 31, 2021

Restricted Cash And Cash Equivalents [Abstract]

Restricted Cash

5. Restricted cash

As of December 31, 2021 and 2020, the Company maintained standby letters of credit of $8.8 million and $2.1 million, respectively, which are collateralized with a bank account at a financial institution in accordance with the applicable lease agreements. The following table sets forth the standby letters of credit associated with the leases for each of the Company’s locations:

	December 31,
	2021		2020
	(in thousands)
Fremont, CA	$	6,676	$	-
Cambridge, MA		961		961
South San Francisco, CA		816		816
Seattle, WA		366		366
Total restricted cash	$	8,819	$	2,143

Fair Value Measurements

12 Months Ended

Dec. 31, 2021

Fair Value Disclosures [Abstract]

Fair Value Measurements

6. Fair value measurements

The following tables summarize the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy:

		December 31, 2021
	Valuation Hierarchy	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
		(in thousands)
Financial assets:
Cash equivalents:
Money market funds	Level 1	$	224,671	$	-	$	-		$	224,671
Corporate debt securities	Level 2		2,345		-		-			2,345
Total cash equivalents			227,016		-		-			227,016
Short-term marketable securities:
U.S. government and agency securities	Level 2		162,854		1		(195	)		162,660
Corporate debt securities	Level 2		135,441		-		(134	)		135,307
Total short-term marketable securities			298,295		1		(329	)		297,967
Long-term marketable securities:
U.S. government and agency securities	Level 2		176,492		-		(925	)		175,567
Corporate debt securities	Level 2		20,427		-		(113	)		20,314
Total long-term marketable securities			196,919		-		(1,038	)		195,881
Other assets	Level 3		426		-		-			426
Total financial assets		$	722,656	$	1	$	(1,367	)	$	721,290
Financial liabilities:
Short-term financial liabilities:
Contingent consideration	Level 3	$	51,382	$	-	$	-		$	51,382
Success payment liabilities	Level 3		5,000		-		-			5,000
Total short-term financial liabilities			56,382		-		-			56,382
Long-term financial liabilities:
Contingent consideration	Level 3		102,361		-		-			102,361
Success payment liabilities	Level 3		97,525		-		-			97,525
Total long-term financial liabilities			199,886		-		-			199,886
Total financial liabilities		$	256,268	$	-	$	-		$	256,268

		December 31, 2020
	Valuation Hierarchy	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
		(in thousands)
Financial assets:
Cash equivalents:
Money market funds	Level 1	$	48,359	$	-	$	-		$	48,359
U.S. government and agency securities	Level 2		40,727		1		(1	)		40,727
Corporate debt securities	Level 2		1,138		-		-			1,138
Total cash equivalents			90,224		1		(1	)		90,224
Short-term marketable securities:
U.S. government and agency securities	Level 2		244,637		30		(5	)		244,662
Corporate debt securities	Level 2		8,798		-		(2	)		8,796
Total short-term marketable securities			253,435		30		(7	)		253,458
Long-term marketable securities:
U.S. government and agency securities	Level 2		33,724		7		-			33,731
Total long-term marketable securities			33,724		7		-			33,731
Total financial assets		$	377,383	$	38	$	(8	)	$	377,413
Financial liabilities:
Long-term financial liabilities:
Contingent consideration	Level 3	$	121,901	$	-	$	-		$	121,901
Success payment liabilities	Level 3		76,494		-		-			76,494
Total financial liabilities		$	198,395	$	-	$	-		$	198,395

The Company measures the fair value of money market funds based on quoted prices in active markets for identical assets or liabilities. The Level 2 marketable securities include U.S. government, agency securities, and corporate debt securities and are valued based on either recent trades of securities in inactive markets or quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data. As of December 31, 2021, all marketable securities had an effective maturity date of two years or less.

Securities in an unrealized loss position have been in an unrealized loss position for less than one year. The Company determined that there was no material change in the credit risk of the above investments during the year ended December 31, 2021. As such, an allowance for credit losses has not been recognized. As of December 31, 2021, the Company does not intend to sell such securities, and it is not more-likely-than-not that the Company will be required to sell the securities prior to the recovery of the amortized cost basis.

As of December 31, 2021 and 2020, the balance in accumulated other comprehensive income (loss) included net unrealized gains (losses) related to the Company’s available-for-sale debt securities. There were no material realized gains or losses recognized on the sale or maturity of available-for-sale securities during the years ended December 31, 2021, 2020 and 2019.

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities:

	Contingent Consideration			Cobalt Success Payment Liability			Harvard Success Payment Liability
	(in thousands)
Balance as of December 31, 2020	$	121,901		$	64,694		$	11,800
Changes in fair value - expense (gain)		11,393			91,757			23,900
Balance as of March 31, 2021		133,294			156,451			35,700
Changes in fair value - expense (gain)		7,163			(66,632	)		(16,556	)
Balance as of June 30, 2021		140,457			89,819			19,144
Changes in fair value - expense (gain)		(8,476	)		21,790			3,439
Balance as of September 30, 2021		131,981			111,609			22,583
Changes in fair value - expense (gain)		21,762			(23,256	)		(8,411	)
Balance as of December 31, 2021	$	153,743		$	88,353		$	14,172

Contingent consideration

The Company utilizes significant estimates and assumptions it believes would be made by a market participant in determining the estimated fair value of the Cobalt Contingent Consideration at each balance sheet date. The fair value of the Cobalt Contingent Consideration was determined by calculating the probability-weighted estimated value of the pre-specified development milestone payments based on the assessment of the likelihood and estimated timing that the milestones would be achieved and the applicable discount rates. The discount rate captures the credit risk associated with the payment of the contingent consideration when earned and due. The Company assesses these estimates on an on-going basis as additional data impacting the assumptions are obtained.

The fair value of the Cobalt Contingent Consideration was calculated using the following unobservable inputs:

	December 31,
	2021		2020
Unobservable Input	Range	Weighted-Average	Range	Weighted-Average
Discount rates	10.9% - 11.6%	11.2%	10.5% - 10.8%	10.6%
Probability of milestone achievement	5.0% - 75.0%	33.8%	2.5% - 65.0%	27.6%

The weighted-average unobservable inputs were calculated based on the relative value of the pre-specified development milestones. The estimated fair value of the Cobalt Contingent Consideration may change significantly as development progresses and additional data are obtained, impacting the assumptions regarding probabilities of successful achievement of the milestones used to estimate the fair value of the liability and the timing in which they are expected to be achieved. In evaluating the fair value assumptions, judgment is required to interpret the market data used to develop the estimates. The estimates of fair value may not be indicative of the amounts that could be realized in a current market exchange. Accordingly, the use of different market assumptions, inputs, and/or different valuation techniques could result in materially different fair value estimates.

Success payments

The Company utilizes significant estimates and assumptions in determining the estimated fair value of the success payment liabilities and the associated expense or gain at each balance sheet date. The estimated fair value of the Cobalt and Harvard success payment liabilities was determined using a Monte Carlo simulation methodology, which models the estimated fair value of the liability based on several key assumptions, including the expected volatility, remaining term, risk-free interest rate, estimated number and timing of valuation measurement dates on the basis of which payment may be triggered, and for the Cobalt Success Payment, the Company’s market capitalization, and for the Harvard Success Payments, the per share fair value of the Company’s common stock.

Prior to the IPO, the calculation of the estimated fair value of the success payment liabilities incorporated the estimated future per share value of the Company’s Series A convertible preferred stock and the estimated future value of the Company implied by the estimated future per share value of the Company’s Series B convertible preferred stock at issuance. Concurrent with the closing of the Company’s IPO in February 2021, the Company’s Series A and Series B convertible preferred stock converted into common stock. As such, subsequent to the IPO, the computation of the estimated fair value of the Harvard Success Payment liabilities incorporates the per share fair market value of the Company’s common stock, and the estimated fair value of the Cobalt Success Payment liability incorporates the market capitalization of the Company.

The fair values of the Cobalt and Harvard success payments were calculated using the following unobservable inputs:

	December 31,
	2021		2020
Unobservable Input	Cobalt	Harvard	Cobalt	Harvard
Expected stock price volatility	70%	70%	70%	70%
Expected term (years)	17.1	9.2	18.1	10.2

- 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

Property and Equipment, Net

12 Months Ended

Dec. 31, 2021

Property Plant And Equipment [Abstract]

Property and Equipment, Net

7. Property and equipment, net

Property and equipment, net consists of the following:

	December 31,
	2021			2020
	(in thousands)
Laboratory equipment	$	47,684		$	29,665
Leasehold improvements		33,848			15,598
Construction in progress		1,388			8,323
Computer equipment, software, and other		1,318			926
Total property and equipment, at cost		84,238			54,512
Less: Accumulated depreciation		(18,774	)		(7,737	)
Property and equipment, net	$	65,464		$	46,775

Depreciation expense was $11.1 million, $5.9 million, and $1.8 million, respectively, for the years ended December 31, 2021, 2020, and 2019.

Accrued Liabilities

12 Months Ended

Dec. 31, 2021

Payables And Accruals [Abstract]

Accrued liabilities

8. Accrued liabilities

Accrued compensation and accrued expenses and other current liabilities consist of the following:

	December 31,
	2021		2020
	(in thousands)
Accrued compensation:
Accrued bonus	$	13,814	$	11,582
Accrued paid time off		4,429		2,441
Accrued payroll		2,888		1,997
Total accrued compensation	$	21,131	$	16,020
Accrued expenses and other current liabilities:
Accrued research and development expense services	$	3,419	$	1,197
Accrued property and equipment		2,566		2,892
Accrued professional fees		1,971		1,717
Other accrued current liabilities		2,388		3,660
Total accrued expenses and other current liabilities	$	10,344	$	9,466

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

9. Commitments and contingencies

Lease commitments

The Company’s lease portfolio is primarily composed of operating leases for office, laboratory, non-good manufacturing practices (GMP) pilot plant manufacturing, and industrial space located in Seattle, WA, Cambridge, MA, South San Francisco, CA, and Fremont, CA. Our operating leases have contractual periods expiring between April 2024 and November 2031. These leases contain various rent abatement periods, after which they require monthly lease payments that may be subject to annual increases throughout the lease term. The Seattle and South San Francisco lease agreements each provide the Company with the option to renew for an additional period of five years. The Company is not reasonably certain it will renew these leases, and the renewal options therefore are not considered in the remaining lease term for these leases. The industrial space located in Fremont, CA will be used for the construction of a GMP manufacturing facility. The lease agreement initial term is ten years and includes the option to extend for up to two additional five-year terms. The Company anticipates that it will exercise both options to extend. Certain leases provide the Company with the right to make tenant improvements, including the addition of laboratory space or build-out of manufacturing

capabilities, and include a lease incentive allowance. The following table contains additional information related to the Company’s operating leases:

Location	Approximate Square Footage	Commencement Dates	Expiration Dates
Seattle, WA	48,086	March 2019 to September 2020	December 2026 to April 2028
Cambridge, MA	59,639	March 2019 to May 2020	November 2025 to February 2028
South San Francisco, CA	66,075	December 2019 to November 2021	April 2024 to April 2030
Fremont, CA	163,193	July 2021	November 2031

Throughout the term of the lease agreements, the Company is responsible for paying certain operating costs in addition to rent, such as common area maintenance, taxes, utilities, and insurance. These additional charges are considered variable lease costs and are recognized in the period in which the costs are incurred.

The following table summarizes the Company’s lease costs:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Operating lease cost	$	16,425	$	10,757	$	4,898
Short-term lease cost		512		1,886		3,710
Variable lease cost		5,230		3,081		1,494
Total lease cost	$	22,167	$	15,724	$	10,102

As of December 31, 2021, the weighted-average remaining lease term was 9.88 years and the weighted-average IBR was 9.15%.

The following table reconciles the Company’s undiscounted operating lease cash flows by fiscal year to the present value of the operating lease liabilities as of December 31, 2021 (in thousands):

2022		19,954
2023		21,511
2024		20,601
2025		20,449
2026		17,701
2026 and thereafter		80,913
Total undiscounted lease payments		181,129
Less: imputed interest		(66,291	)
Less: tenant improvement allowances		(3,895	)
Present value of operating lease liabilities	$	110,943

Convertible Preferred Stock

12 Months Ended

Dec. 31, 2021

Stockholders Equity Note [Abstract]

Convertible preferred stock

10. Convertible preferred stock

Series A-1, A-2, and B convertible preferred stock financings

In 2018 and 2019, the Company issued 67.5 million shares of its Series A-1 and Series A-2 convertible preferred stock at a price of $4.00 per share, for gross proceeds of $269.9 million. In 2020, the Company issued 27.2 million shares of Series B convertible preferred stock at $16.00 per share for gross proceeds of $435.5 million.

In December 2020, the Company amended and restated its certificate of incorporation and amended the investors’ rights agreement and voting agreement with its stockholders. Under the Company’s amended and restated certificate of incorporation, the authorized capital stock of the Company increased to 707.0 million shares. The authorized shares consisted of 169.2 million shares designated as common stock and 537.8 million shares designated as convertible preferred stock, each with a par value of $0.0001 per share.

Stockholders' Equity

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Stockholders' Equity

11. Stockholders’ equity

Effective February 2021, the Company amended and restated its certificate of incorporation, increasing the number of shares of all classes of stock the Company has authority to issue to 800.0 million shares, of which 750.0 million shares are common stock and 50.0 million shares are preferred stock.

As of December 31, 2021, there were 184.9 million shares of the Company’s common stock outstanding, excluding 4.4 million shares of restricted common stock outstanding that are subject to vesting requirements. As of December 31, 2020, there were 16.2 million shares of the Company’s common stock outstanding, excluding 10.1 million shares of restricted common stock outstanding that are subject to vesting requirements.

- 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

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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stock-Based Compensation

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-based compensation

12. Stock-based compensation

2021 Incentive Award Plan

In February 2021, the Company adopted the 2021 Incentive Award Plan (2021 Plan), which became effective on the completion of the Company’s IPO. The 2021 Plan provides for a variety of stock-based compensation awards, including stock options, restricted stock awards (RSAs), and restricted stock units (RSUs). In conjunction with adopting the 2021 Plan, the Company discontinued the 2018 Equity Incentive Plan with respect to new equity awards.

The 2021 Plan provides for an annual increase in the shares available for issuance thereunder, to be added on the first day of each year, beginning in 2022 and ending in 2031, equal to the lesser of (i) 5% of the outstanding shares of the Company’s common stock on the last day of the immediately preceding year, or (ii) such smaller number of shares determined by the board of directors or an authorized committee of the board of directors. As of December 31, 2021, the total number of shares available for future issuance of awards under the 2021 Plan was 13.2 million. As a result of the operation of this provision, on January 1, 2022, an additional 9.5 million shares became available for issuance under the 2021 Plan.

2021 Employee Stock Purchase Plan

In February 2021, the Company adopted the 2021 Employee Stock Purchase Plan (2021 ESPP), which became effective on the completion of the Company’s IPO. The 2021 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their earnings, subject to plan limitations. Unless otherwise determined by the Company’s board of directors, employees may purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first date of an offering or on the purchase date. The Company may specify offerings with durations of not more than 27 months and may specify shorter purchase periods within each offering.

The 2021 ESPP also provides for an annual share increase, to be added on the first day of each year, beginning in 2022 and ending in 2031, equal to the lesser of (i) 1% of the outstanding shares of the Company’s common stock on the last day of the immediately preceding year and (ii) such number of shares determined by the board of directors or authorized committee of the board of directors, provided that no more than 27.9 million shares may be issued under the 2021 ESPP. As of December 31, 2021, the total number of shares available for future issuance pursuant to the 2021 ESPP was 1.9 million. As a result of the operation of this provision, on January 1, 2022, an additional 1.9 million shares became available for issuance under the 2021 ESPP.

Stock-based compensation expense

Stock-based compensation expense is recognized in the consolidated statements of operations as follows:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Research and development	$	15,239	$	4,888	$	1,246
General and administrative		7,123		940		251
Total stock-based compensation expense	$	22,362	$	5,828	$	1,497

Unrecognized stock-based compensation costs related to unvested awards and the weighted-average period over which the costs are expected to be recognized as of December 31, 2021 are as follows:

	Stock Options		RSAs		RSUs
Unrecognized stock-based compensation expense (in thousands)	$	81,140	$	1,892	$	1,220
Weighted-average period costs expected to be recognized (in years)		3.2		1.5		1.5

Stock options

A summary of the Company’s stock option activity is as follows:

	Stock Options (in thousands)			Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2020		15,677		$	4.52
Granted		4,165			22.57
Exercised		(1,586	)		2.00
Forfeited/Cancelled		(919	)		6.88
Outstanding as of December 31, 2021		17,337		$	8.96		8.7	$	141,718
Exercisable as of December 31, 2021		3,215		$	2.61		8.1	$	41,382

The fair value of stock options granted to employees, directors, and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:

	Year Ended December 31,
Assumptions	2021	2020	2019
Risk free interest rate	0.46% - 1.38%	0.36% - 1.51%	1.53% - 2.62%
Expected volatility	70%	70%	70%
Expected term (years)	5.50 - 6.40	6.25 - 6.75	6.02 - 6.25
Expected dividend	0%	0%	0%

The following table summarizes additional information related to stock option activity:

	Year Ended December 31,
	2021		2020		2019
Weighted average grant date fair value per share for options granted	$	14.22	$	3.52	$	0.92
Aggregate intrinsic value of stock options exercised (in thousands)	$	29,880	$	605	$	25

Restricted stock

A summary of the Company’s RSA and RSU activity is as follows:

	RSAs (in thousands)			RSAs Weighted-Average Grant Date Fair Value per Share		RSUs (in thousands)			RSUs Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2020		10,079		$	0.33		326		$	1.44
Granted		-			-		57			21.37
Vested		(5,691	)		0.25		(225	)		1.44
Forfeited		(23	)		1.00		(17	)		1.44
Unvested shares as of December 31, 2021		4,365		$	0.43		141		$	9.43

The fair value of vested RSAs was $1.5 million, $1.5 million and $1.0 million, respectively, for the years ended December 31, 2021, 2020 and 2019. The fair value of vested RSUs was $4.1 million for the year ended December 31, 2021 and immaterial for each of the years ended December 31, 2020 and 2019.

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Income Taxes

13. Income taxes

As of December 31, 2021, the Company had U.S. federal and state tax-effected net operating loss (NOL) carryforwards of $101.9 million and $12.4 million, respectively, which are available to reduce future taxable income. As of December 31, 2021, the Company also had federal and state research tax credits of $17.5 million and $6.5 million, respectively, which may be used to offset future liabilities. The federal NOL carries forward indefinitely, and the state NOL will begin to expire in 2038. The federal tax credit carryforward will begin to expire in 2038, and the state tax credit will carry forward indefinitely. The NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. Subsequent ownership changes may further affect the limitation in future years.

In connection with the 2019 Cobalt acquisition, the Company recorded a deferred tax liability of $7.5 million associated with the acquired intangible asset, and the Company recorded a tax benefit of $7.5 million for the year ended December 31, 2019 related to the release of valuation allowance on U.S. deferred tax assets as a result of this deferred tax liability.

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows:

	Year Ended December 31,
	2021			2020			2019
Federal statutory tax		21.00	%		21.00	%		21.00	%
State income tax, net of federal benefit		2.75			2.09			3.06
Valuation allowance		(24.06	)		(15.18	)		(16.32	)
Success payment liabilities		(1.40	)		(4.58	)		-
Contingent consideration		(1.88	)		(3.89	)		(2.71	)
Tax credits		2.58			1.88			1.93
Other		1.01			(1.32	)		(1.50	)
Effective income tax rate		0.00	%		0.00	%		5.46	%

The principal components of the Company’s net deferred tax assets are as follows:

	December 31,
	2021			2020
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	114,368		$	58,527
Lease liabilities		25,754			16,971
Tax credit carryforwards		24,008			11,908
Intangibles		5,986			-
Accrued liabilities and allowances		4,401			3,643
Success payment liabilities		3,290			2,785
Stock-based compensation		1,854			-
Other		-			25
Gross deferred tax assets		179,661			93,859
Valuation allowance		(156,622	)		(70,989	)
Deferred tax assets, net of valuation allowance		23,039			22,870
Deferred tax liabilities:
Right-of-use assets		(21,940	)		(14,577	)
Fixed assets		(1,050	)		(935	)
Intangibles		-			(6,870	)
Stock-based compensation		-			(488	)
Other		(49	)		-
Deferred tax liabilities		(23,039	)		(22,870	)
Net deferred taxes assets	$	-		$	-

The valuation allowance relates primarily to net U.S. deferred tax assets from operating losses, research tax credit carryforwards, and amounts paid and accrued to enter into various agreements for which the tax treatment requires capitalization and amortization.

The Company maintains a full valuation allowance on its net U.S. deferred tax assets. The assessment regarding whether a valuation allowance is required considers both positive and negative evidence when determining whether it is more likely than not that deferred tax assets are recoverable. In making this assessment, significant weight is given to evidence that can be objectively verified. In its evaluation, the Company considered its cumulative loss in the first year of operation and its forecasted losses in the near term as significant negative evidence. Based upon a review of the four sources of income identified within ASC 740, Accounting for Income Taxes, the Company determined that the negative evidence outweighed the positive evidence, and a full valuation allowance on its net deferred tax assets should be maintained. The Company will continue to assess the realizability of its deferred tax assets going forward and will adjust the valuation allowance as needed.

The Company determines its uncertain tax positions based on a determination of whether and how much of the tax benefit the Company takes in its tax filings or positions is more likely than not to be sustained upon examination by the relevant income tax

authorities. The Company is generally subject to examination by U.S. federal and local income tax authorities for all tax years in which the loss carryforward is available. The Company applies judgment in its determination of the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. As of December 31, 2021 and 2020, the Company’s uncertain tax positions were immaterial.

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

Net Loss Per Share

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Net Loss Per Share

14. Net loss per share

Basic and diluted net loss per common share are calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, without consideration for common stock equivalents. The Company was in a loss position for all periods presented, and basic net loss per share and diluted net loss per share are therefore the same for all periods, as the inclusion of all potential common securities outstanding would have been anti-dilutive.

The following table summarizes the calculation of basic and diluted net loss per share of common stock:

	Year Ended December 31,
	2021			2020			2019
	(in thousands, except per share amounts)
Net loss	$	(355,928	)	$	(285,305	)	$	(130,778	)
Weighted-average number of common shares - basic and diluted		166,433			13,014			4,903
Net loss per common share - basic and diluted	$	(2.14	)	$	(21.92	)	$	(26.68	)

The following securities were excluded from the computation of net loss per diluted share of common stock for periods presented as their effect would have been anti-dilutive:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Convertible preferred stock		-		134,113		106,890
Options to purchase common stock		17,337		15,677		3,549
Unvested restricted common stock		4,365		10,079		17,140
Unvested RSUs		141		326		345
Total		21,843		160,195		127,924

Employee Benefit Plan

12 Months Ended

Dec. 31, 2021

Compensation And Retirement Disclosure [Abstract]

Employee Benefit Plan

15. Employee benefit plan

In January 2019, the Company adopted a 401(k) retirement and savings plan (the 401(k) Plan) covering all employees. The 401(k) Plan allows employees to make pre- and post-tax contributions up to the maximum allowable amount set by the IRS. The Company has not made any matching contributions to the 401(k) Plan on behalf of participants.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Basis of presentation

Use of estimates

Cash and cash equivalents

Marketable securities

Concentrations of credit risk and off-balance sheet risk

Fair value measurement

Level 1 – Quoted prices in active markets for identical assets or liabilities.

Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability.

Property and equipment, net

resulting gain or loss is recorded in other income (expense), net in the period realized. Maintenance and repairs are expensed as incurred.

Impairment of long-lived assets

Acquisitions

Goodwill and intangible assets

Contingent consideration from business combinations

Success payments

Leases

Claims and contingencies

Convertible preferred stock

Stock-based compensation

•

Fair Value of Common Stock—The fair value of common stock is based on the closing price as reported on The Nasdaq Global Select Market on the date of grant.

•

Expected Dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Research and development expense

Research and development related success payment and contingent consideration

General and administrative expenses

Income taxes

Segments

JOBS Act accounting election

Recent accounting pronouncements

Recently adopted

Not yet adopted

ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment

Acquisitions - (Tables) - Cobalt Biomedicine Inc

12 Months Ended

Dec. 31, 2021

Business Acquisition [Line Items]

Schedule of Purchase Consideration

Series A-2 convertible preferred stock issued⁽¹⁾	$	97,178
First milestone - restricted Series A-2 convertible preferred stock⁽²⁾		38,769
Success payment⁽³⁾		2,428
Fair value of contingent consideration⁽⁴⁾		51,248
Other		66
Total consideration	$	189,689

(1)

(2)

(3)

(4)

Components of Purchase Price Allocation

Net working capital	$	(3,275	)
Property and equipment		689
Net liabilities assumed		(2,586	)
Deferred tax liability		(7,547	)
Acquired in-process research and development		59,195
Goodwill		140,627
Total consideration	$	189,689

Schedule of Various Thresholds for Market Capitalizations Resulting Potential Success Payment and Additional Potential Contingent Consideration

Sana market capitalization upon a change of control and resulting impact to Cobalt Success Payment and additional potential Cobalt Contingent Consideration	Cobalt Success Payment		Additional potential Cobalt Contingent Consideration
	(in millions)
Equal to or exceeds $8.1 billion	$	500	$	-
Equal to or exceeds $7.4 billion, but less than $8.1 billion		150		350
Equal to or exceeds $6.8 billion, but less than $7.4 billion		100		400
Less than $6.8 billion		-		500

License and collaboration agreements (Tables)

12 Months Ended

Dec. 31, 2021

License And Collaboration Agreements [Abstract]

Summary of Potential Success Payments

The following table summarizes the potential success payments and common stock price required for payment:

Multiple of Equity Value at Issuance	5x		10x		20x		30x		40x
Per share common stock price required for payment	$	20.00	$	40.00	$	80.00	$	120.00	$	160.00
Success payment(s) (in millions)	$	5.0	$	15.0	$	30.0	$	50.0	$	75.0

Restricted Cash (Tables)

12 Months Ended

Dec. 31, 2021

Restricted Cash And Cash Equivalents [Abstract]

Summary of Restricted Cash

The following table sets forth the standby letters of credit associated with the leases for each of the Company’s locations:

	December 31,
	2021		2020
	(in thousands)
Fremont, CA	$	6,676	$	-
Cambridge, MA		961		961
South San Francisco, CA		816		816
Seattle, WA		366		366
Total restricted cash	$	8,819	$	2,143

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value Assets and Liabilities Measured on Recurring Basis

The following tables summarize the Company’s financial assets and liabilities measured at fair value on a recurring basis based on the three-tier fair value hierarchy:

		December 31, 2021
	Valuation Hierarchy	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
		(in thousands)
Financial assets:
Cash equivalents:
Money market funds	Level 1	$	224,671	$	-	$	-		$	224,671
Corporate debt securities	Level 2		2,345		-		-			2,345
Total cash equivalents			227,016		-		-			227,016
Short-term marketable securities:
U.S. government and agency securities	Level 2		162,854		1		(195	)		162,660
Corporate debt securities	Level 2		135,441		-		(134	)		135,307
Total short-term marketable securities			298,295		1		(329	)		297,967
Long-term marketable securities:
U.S. government and agency securities	Level 2		176,492		-		(925	)		175,567
Corporate debt securities	Level 2		20,427		-		(113	)		20,314
Total long-term marketable securities			196,919		-		(1,038	)		195,881
Other assets	Level 3		426		-		-			426
Total financial assets		$	722,656	$	1	$	(1,367	)	$	721,290
Financial liabilities:
Short-term financial liabilities:
Contingent consideration	Level 3	$	51,382	$	-	$	-		$	51,382
Success payment liabilities	Level 3		5,000		-		-			5,000
Total short-term financial liabilities			56,382		-		-			56,382
Long-term financial liabilities:
Contingent consideration	Level 3		102,361		-		-			102,361
Success payment liabilities	Level 3		97,525		-		-			97,525
Total long-term financial liabilities			199,886		-		-			199,886
Total financial liabilities		$	256,268	$	-	$	-		$	256,268

		December 31, 2020
	Valuation Hierarchy	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
		(in thousands)
Financial assets:
Cash equivalents:
Money market funds	Level 1	$	48,359	$	-	$	-		$	48,359
U.S. government and agency securities	Level 2		40,727		1		(1	)		40,727
Corporate debt securities	Level 2		1,138		-		-			1,138
Total cash equivalents			90,224		1		(1	)		90,224
Short-term marketable securities:
U.S. government and agency securities	Level 2		244,637		30		(5	)		244,662
Corporate debt securities	Level 2		8,798		-		(2	)		8,796
Total short-term marketable securities			253,435		30		(7	)		253,458
Long-term marketable securities:
U.S. government and agency securities	Level 2		33,724		7		-			33,731
Total long-term marketable securities			33,724		7		-			33,731
Total financial assets		$	377,383	$	38	$	(8	)	$	377,413
Financial liabilities:
Long-term financial liabilities:
Contingent consideration	Level 3	$	121,901	$	-	$	-		$	121,901
Success payment liabilities	Level 3		76,494		-		-			76,494
Total financial liabilities		$	198,395	$	-	$	-		$	198,395

Changes in Estimated Fair Value of Level 3 Financial Liabilities

The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial liabilities:

	Contingent Consideration			Cobalt Success Payment Liability			Harvard Success Payment Liability
	(in thousands)
Balance as of December 31, 2020	$	121,901		$	64,694		$	11,800
Changes in fair value - expense (gain)		11,393			91,757			23,900
Balance as of March 31, 2021		133,294			156,451			35,700
Changes in fair value - expense (gain)		7,163			(66,632	)		(16,556	)
Balance as of June 30, 2021		140,457			89,819			19,144
Changes in fair value - expense (gain)		(8,476	)		21,790			3,439
Balance as of September 30, 2021		131,981			111,609			22,583
Changes in fair value - expense (gain)		21,762			(23,256	)		(8,411	)
Balance as of December 31, 2021	$	153,743		$	88,353		$	14,172

Cobalt Contingent Consideration Liability

Summary of Estimated Fair Value of Liabilities using Unobservable Inputs

The fair value of the Cobalt Contingent Consideration was calculated using the following unobservable inputs:

	December 31,
	2021		2020
Unobservable Input	Range	Weighted-Average	Range	Weighted-Average
Discount rates	10.9% - 11.6%	11.2%	10.5% - 10.8%	10.6%
Probability of milestone achievement	5.0% - 75.0%	33.8%	2.5% - 65.0%	27.6%

Success Payment Liabilities

Summary of Estimated Fair Value of Liabilities using Unobservable Inputs

The fair values of the Cobalt and Harvard success payments were calculated using the following unobservable inputs:

	December 31,
	2021		2020
Unobservable Input	Cobalt	Harvard	Cobalt	Harvard
Expected stock price volatility	70%	70%	70%	70%
Expected term (years)	17.1	9.2	18.1	10.2

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2021

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consists of the following:

	December 31,
	2021			2020
	(in thousands)
Laboratory equipment	$	47,684		$	29,665
Leasehold improvements		33,848			15,598
Construction in progress		1,388			8,323
Computer equipment, software, and other		1,318			926
Total property and equipment, at cost		84,238			54,512
Less: Accumulated depreciation		(18,774	)		(7,737	)
Property and equipment, net	$	65,464		$	46,775

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2021

Payables And Accruals [Abstract]

Schedule of Accrued Compensation and Accrued Expenses and Other Current Liabilities

Accrued compensation and accrued expenses and other current liabilities consist of the following:

	December 31,
	2021		2020
	(in thousands)
Accrued compensation:
Accrued bonus	$	13,814	$	11,582
Accrued paid time off		4,429		2,441
Accrued payroll		2,888		1,997
Total accrued compensation	$	21,131	$	16,020
Accrued expenses and other current liabilities:
Accrued research and development expense services	$	3,419	$	1,197
Accrued property and equipment		2,566		2,892
Accrued professional fees		1,971		1,717
Other accrued current liabilities		2,388		3,660
Total accrued expenses and other current liabilities	$	10,344	$	9,466

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Schedule of Additional Information Related to Operating Leases

The following table contains additional information related to the Company’s operating leases:

Location	Approximate Square Footage	Commencement Dates	Expiration Dates
Seattle, WA	48,086	March 2019 to September 2020	December 2026 to April 2028
Cambridge, MA	59,639	March 2019 to May 2020	November 2025 to February 2028
South San Francisco, CA	66,075	December 2019 to November 2021	April 2024 to April 2030
Fremont, CA	163,193	July 2021	November 2031

Summary of Lease Costs

The following table summarizes the Company’s lease costs:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Operating lease cost	$	16,425	$	10,757	$	4,898
Short-term lease cost		512		1,886		3,710
Variable lease cost		5,230		3,081		1,494
Total lease cost	$	22,167	$	15,724	$	10,102

Reconciliation of Undiscounted Operating Lease Cash Flows by Fiscal Year to Present Value of Operating Lease Liabilities

The following table reconciles the Company’s undiscounted operating lease cash flows by fiscal year to the present value of the operating lease liabilities as of December 31, 2021 (in thousands):

2022		19,954
2023		21,511
2024		20,601
2025		20,449
2026		17,701
2026 and thereafter		80,913
Total undiscounted lease payments		181,129
Less: imputed interest		(66,291	)
Less: tenant improvement allowances		(3,895	)
Present value of operating lease liabilities	$	110,943

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock Based Compensation Expense Recognized

Stock-based compensation expense is recognized in the consolidated statements of operations as follows:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Research and development	$	15,239	$	4,888	$	1,246
General and administrative		7,123		940		251
Total stock-based compensation expense	$	22,362	$	5,828	$	1,497

Schedule of Unrecognized Stock-Based Compensation Costs Related to Unvested Awards and Weighted-Average Period Over Which Costs are Expected to be Recognized

Unrecognized stock-based compensation costs related to unvested awards and the weighted-average period over which the costs are expected to be recognized as of December 31, 2021 are as follows:

	Stock Options		RSAs		RSUs
Unrecognized stock-based compensation expense (in thousands)	$	81,140	$	1,892	$	1,220
Weighted-average period costs expected to be recognized (in years)		3.2		1.5		1.5

Summary of Stock Option Activity

A summary of the Company’s stock option activity is as follows:

	Stock Options (in thousands)			Weighted-Average Exercise Price per Share		Weighted-Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2020		15,677		$	4.52
Granted		4,165			22.57
Exercised		(1,586	)		2.00
Forfeited/Cancelled		(919	)		6.88
Outstanding as of December 31, 2021		17,337		$	8.96		8.7	$	141,718
Exercisable as of December 31, 2021		3,215		$	2.61		8.1	$	41,382

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model for Estimating Fair Value of Stock Options Granted

The fair value of stock options granted to employees, directors, and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:

	Year Ended December 31,
Assumptions	2021	2020	2019
Risk free interest rate	0.46% - 1.38%	0.36% - 1.51%	1.53% - 2.62%
Expected volatility	70%	70%	70%
Expected term (years)	5.50 - 6.40	6.25 - 6.75	6.02 - 6.25
Expected dividend	0%	0%	0%

Summary of Additional Information Related to Stock Option Activity

The following table summarizes additional information related to stock option activity:

	Year Ended December 31,
	2021		2020		2019
Weighted average grant date fair value per share for options granted	$	14.22	$	3.52	$	0.92
Aggregate intrinsic value of stock options exercised (in thousands)	$	29,880	$	605	$	25

Summary of RSA Activity

A summary of the Company’s RSA and RSU activity is as follows:

	RSAs (in thousands)			RSAs Weighted-Average Grant Date Fair Value per Share		RSUs (in thousands)			RSUs Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2020		10,079		$	0.33		326		$	1.44
Granted		-			-		57			21.37
Vested		(5,691	)		0.25		(225	)		1.44
Forfeited		(23	)		1.00		(17	)		1.44
Unvested shares as of December 31, 2021		4,365		$	0.43		141		$	9.43

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Reconciliation of Income Taxes Computed Using U.S Federal Statutory Tax Rate

A reconciliation of income taxes computed using the U.S. federal statutory rate to that reflected in operations follows:

	Year Ended December 31,
	2021			2020			2019
Federal statutory tax		21.00	%		21.00	%		21.00	%
State income tax, net of federal benefit		2.75			2.09			3.06
Valuation allowance		(24.06	)		(15.18	)		(16.32	)
Success payment liabilities		(1.40	)		(4.58	)		-
Contingent consideration		(1.88	)		(3.89	)		(2.71	)
Tax credits		2.58			1.88			1.93
Other		1.01			(1.32	)		(1.50	)
Effective income tax rate		0.00	%		0.00	%		5.46	%

Components of Net Deferred Tax Assets

The principal components of the Company’s net deferred tax assets are as follows:

	December 31,
	2021			2020
	(in thousands)
Deferred tax assets:
Net operating loss carryforwards	$	114,368		$	58,527
Lease liabilities		25,754			16,971
Tax credit carryforwards		24,008			11,908
Intangibles		5,986			-
Accrued liabilities and allowances		4,401			3,643
Success payment liabilities		3,290			2,785
Stock-based compensation		1,854			-
Other		-			25
Gross deferred tax assets		179,661			93,859
Valuation allowance		(156,622	)		(70,989	)
Deferred tax assets, net of valuation allowance		23,039			22,870
Deferred tax liabilities:
Right-of-use assets		(21,940	)		(14,577	)
Fixed assets		(1,050	)		(935	)
Intangibles		-			(6,870	)
Stock-based compensation		-			(488	)
Other		(49	)		-
Deferred tax liabilities		(23,039	)		(22,870	)
Net deferred taxes assets	$	-		$	-

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

Summary of Calculation of Basic and Diluted Net Loss Per Share of Common Stock

The following table summarizes the calculation of basic and diluted net loss per share of common stock:

	Year Ended December 31,
	2021			2020			2019
	(in thousands, except per share amounts)
Net loss	$	(355,928	)	$	(285,305	)	$	(130,778	)
Weighted-average number of common shares - basic and diluted		166,433			13,014			4,903
Net loss per common share - basic and diluted	$	(2.14	)	$	(21.92	)	$	(26.68	)

Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share

The following securities were excluded from the computation of net loss per diluted share of common stock for periods presented as their effect would have been anti-dilutive:

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Convertible preferred stock		-		134,113		106,890
Options to purchase common stock		17,337		15,677		3,549
Unvested restricted common stock		4,365		10,079		17,140
Unvested RSUs		141		326		345
Total		21,843		160,195		127,924

Organization - Additional Information (Details) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended		12 Months Ended
	Feb. 28, 2021 USD ($) $ / shares shares	Jan. 31, 2021	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares	Dec. 31, 2018 shares
Description Of Organization [Line Items]
Reverse stock split, description			In January 2021, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-4 reverse stock split of shares of the Company’s common and convertible preferred stock, which was effected on January 27, 2021.
Reverse stock split, conversion ratio		0.25
Proceeds from public offering of common stock, net of offering costs			$ 626,405
Convertible preferred stock, shares outstanding \| shares			0	134,113
Accumulated deficit			$ 785,360	$ 429,432
Cash, cash equivalents and marketable securities			746,900
Success payment liabilities			100,100
Contingent consideration			$ 102,500
Convertible Preferred Stock
Description Of Organization [Line Items]
Convertible preferred stock, shares outstanding \| shares				134,113	106,890	11,463
Common Stock
Description Of Organization [Line Items]
Conversion of preferred stock into common stock (in shares) \| shares			134,113
IPO
Description Of Organization [Line Items]
Convertible preferred stock, shares outstanding \| shares	134,100
IPO \| Convertible Preferred Stock
Description Of Organization [Line Items]
Conversion of preferred stock into common stock (in shares) \| shares	134,100
Carrying value of converted preferred stock	$ 852,900
IPO \| Common Stock
Description Of Organization [Line Items]
Issuance of common stock in initial public offering, net of offering costs (in shares) \| shares	27,000		27,025
Common stock price per share \| $ / shares	$ 25.00
Proceeds from public offering of common stock, net of offering costs	$ 626,400
Payments of underwriting discounts and commissions	45,200
Offering expenses	$ 4,000
Underwriters' Option To Purchase Additional Shares \| Common Stock
Description Of Organization [Line Items]
Issuance of common stock in initial public offering, net of offering costs (in shares) \| shares	3,500

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($) Segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019	Feb. 28, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Off-balance sheet concentrations of credit risk, description	The Company has no off-balance sheet concentrations of credit risk, such as foreign currency exchange contracts, option contracts, or other hedging arrangements.
Goodwill	$ 140,627,000	$ 140,627,000
Amortization of intangible asset	0
Impairments of intangible asset	$ 0
Expected dividend yield	0.00%	0.00%	0.00%
Number of operating segment \| Segment	1
Allowance for losses on available-for-sale debt securities	$ 0
ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 01, 2021
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Dividends declared	$ 0
Cobalt Biomedicine Inc
Summary Of Significant Accounting Policies [Line Items]
Goodwill				$ 140,627,000
Acquisition Agreement \| Cobalt Biomedicine Inc
Summary Of Significant Accounting Policies [Line Items]
Goodwill	140,600,000			$ 140,600,000
Impairments of goodwill	$ 0
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	5 years

Acquisitions - Additional Information (Details) - USD ($) $ in Thousands, shares in Millions	1 Months Ended				12 Months Ended
	Feb. 28, 2021	Sep. 30, 2020	Nov. 30, 2019	Feb. 28, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill					$ 140,627	$ 140,627
Estimated fair value of contingent consideration, short term liabilities					51,382
Estimated fair value of contingent consideration, long-term liabilities					102,361	121,901
Change in the estimated fair value of contingent consideration					31,842	52,793	$ 17,860
Oscine Corp \| Stock Purchase Agreement
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired		100.00%
Business acquisition, consideration transferred		$ 8,500			8,500
Business acquisition, consideration transferred, cash		7,600
Business acquisition, consideration holdback amount		900
Oscine Corp \| Stock Purchase Agreement \| Maximum
Business Acquisition [Line Items]
Future milestone payments upon achievement of certain development and commercial milestones		$ 225,800
Cytocardia Inc.
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired			100.00%
Business acquisition, consideration transferred			$ 8,000				8,000
Business acquisition, consideration transferred, cash			6,800
Business acquisition, consideration holdback amount			1,200
Cytocardia Inc. \| Maximum
Business Acquisition [Line Items]
Future milestone payments upon achievement of certain development and commercial milestones			$ 140,000
Cobalt Biomedicine Inc
Business Acquisition [Line Items]
Business acquisition, consideration transferred				$ 189,689
Business combination, intangible assets				59,195
Goodwill				140,627
Cobalt Biomedicine Inc \| Acquisition Agreement
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%
Business acquisition, shares restricted based on achievement of prespecified development milestone	12.1
Goodwill				140,600	140,600
Maximum success payment upon achievement of certain pre-specified development milestones				$ 500,000
Maximum period for success payment to achieve				20 years
Cobalt Biomedicine Inc \| Acquisition Agreement \| Research and Development Expense
Business Acquisition [Line Items]
Estimated fair value of success payment liability					88,300	64,700
Estimated fair value of contingent consideration					153,700	121,900
Estimated fair value of contingent consideration, short term liabilities					51,400
Estimated fair value of contingent consideration, long-term liabilities					102,300
(Gain) expense in connection with change in estimated fair value of success payment					23,600	62,300
Change in the estimated fair value of contingent consideration					$ 31,800	$ 52,800	$ 17,900
Cobalt Biomedicine Inc \| Acquisition Agreement \| Market Capitalization Equal to or Exceeds $8.1 billion
Business Acquisition [Line Items]
Cobalt success payment				$ 500,000
Cobalt Biomedicine Inc \| Acquisition Agreement \| IPR&D
Business Acquisition [Line Items]
Business combination, intangible assets				59,200
Cobalt Biomedicine Inc \| Acquisition Agreement \| RSAs
Business Acquisition [Line Items]
Business acquisition, RSAs and RSUs issued	0.7
Cobalt Biomedicine Inc \| Acquisition Agreement \| RSUs
Business Acquisition [Line Items]
Business acquisition, RSAs and RSUs issued	0.3
Cobalt Biomedicine Inc \| Acquisition Agreement \| A-2 Convertible Preferred Stock
Business Acquisition [Line Items]
Business acquisition, shares issued	36.4
Business acquisition, value of shares issued	$ 136,000
Cobalt Biomedicine Inc \| Acquisition Agreement \| Minimum
Business Acquisition [Line Items]
Threshold market capitalization				$ 8,100,000

Acquisitions - Schedule of Purchase Consideration (Details) $ in Thousands	1 Months Ended
	Feb. 28, 2019 USD ($)
Business Acquisition [Line Items]
First milestone - restricted Series A-2 convertible preferred stock	$ 38,800
Cobalt Biomedicine Inc
Business Acquisition [Line Items]
Series A-2 convertible preferred stock issued	97,178
First milestone - restricted Series A-2 convertible preferred stock	38,769
Success payment	2,428
Fair value of contingent consideration	51,248
Other	66
Total consideration	$ 189,689

Acquisitions - Schedule of Purchase Consideration (Parenthetical) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended
	Jul. 31, 2019	Feb. 28, 2019
Business Acquisition [Line Items]
Business combination, shares included in purchase consideration	12.1
First milestone - restricted Series A-2 convertible preferred stock		$ 38.8
Minimum
Business Acquisition [Line Items]
Estimated discount rate		15.30%
Maximum
Business Acquisition [Line Items]
Estimated discount rate		17.60%
A-2 Convertible Preferred Stock
Business Acquisition [Line Items]
Business combination, shares included in purchase consideration		24.3
Stock issued, per share		$ 4.00

Acquisitions - Components of Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Feb. 28, 2019
Business Acquisition [Line Items]
Goodwill	$ 140,627	$ 140,627
Cobalt Biomedicine Inc
Business Acquisition [Line Items]
Net working capital			$ (3,275)
Property and equipment			689
Net liabilities assumed			(2,586)
Deferred tax liability			(7,547)
Acquired in-process research and development			59,195
Goodwill			140,627
Total consideration			$ 189,689

Acquisitions - Schedule of Various Thresholds for Market Capitalizations Resulting Potential Success Payment and Additional Potential Contingent Consideration (Details) - Cobalt Biomedicine Inc $ in Millions	1 Months Ended
	Feb. 28, 2019 USD ($)
Market Capitalization Equal to or Exceeds $8.1 billion
Business Acquisition [Line Items]
Cobalt Success Payment	$ 500
Market Capitalization Equal to or exceeds $7.4 billion, but less than $8.1 billion
Business Acquisition [Line Items]
Cobalt Success Payment	150
Additional potential Cobalt Contingent Consideration	350
Market Capitalization Equal to or exceeds $6.8 billion, but less than $7.4 billion
Business Acquisition [Line Items]
Cobalt Success Payment	100
Additional potential Cobalt Contingent Consideration	400
Market Capitalization Less than $6.8 billion
Business Acquisition [Line Items]
Additional potential Cobalt Contingent Consideration	$ 500

Acquisitions - Schedule of Various Thresholds for Market Capitalizations Resulting Potential Success Payment and Additional Potential Contingent Consideration (Parenthetical) (Details) - Sana $ in Billions	Feb. 28, 2019 USD ($)
Market Capitalization Equal to or Exceeds $8.1 billion
Business Acquisition [Line Items]
Threshold market capitalization	$ 8.1
Market Capitalization Equal to or exceeds $7.4 billion, but less than $8.1 billion
Business Acquisition [Line Items]
Threshold market capitalization	7.4
Market Capitalization Equal to or exceeds $6.8 billion, but less than $7.4 billion
Business Acquisition [Line Items]
Threshold market capitalization	6.8
Market Capitalization Less than $6.8 billion
Business Acquisition [Line Items]
Threshold market capitalization	$ 6.8

License and Collaboration Agreements - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands	1 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Oct. 31, 2021
Series A-2 Convertible Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Share issue price					$ 4.00
Series B Convertible Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Convertible preferred stock shares issued				27,223
Share issue price	$ 16.00
Beam Therapeutics Inc. (Beam) \| Research and Development
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment to collaborators			$ 50,000,000.0
Beam Therapeutics Inc. (Beam) \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Developmental and commercial milestone payments and royalties on licensed products payable						$ 65,000,000.0
Beam Therapeutics Inc. (Beam) \| Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Beneficial ownership percentage held by a member of board of directors						10.00%
Harvard College
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment to collaborators		$ 3,000,000.0
Share issue price		$ 4.00
Total consideration under license agreement		$ 12,000,000.0
Research and development expense					$ 12,000,000.0
Estimated fair value of contingent license payment					4,600,000
Research and development expense				$ 1,400,000	4,600,000
Maximum period expected to achieve for success payments		12 years
Estimated fair value of success payment liability			14,200,000	11,800,000
Harvard College \| Short-term Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated fair value of success payment liability			5,000,000.0	0
Harvard College \| Long-term Liabilities
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Estimated fair value of success payment liability			9,200,000	11,800,000
Harvard College \| Series A-2 Convertible Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Convertible preferred stock shares issued		2,200
Share issue price		$ 4.00
Harvard College \| Series B Convertible Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License payment upon closing of equity financing	$ 6,000,000.0
Harvard College \| Research and Development
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Expense in connection with change in estimated fair value of success payment liability			$ 2,400,000	$ 9,900,000	$ 1,900,000
Harvard College \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential success payment		$ 175,000,000.0

License and Collaboration Agreements - Summary of Potential Success Payments (Details) - Harvard College $ / shares in Units, $ in Millions	1 Months Ended
	Mar. 31, 2019 USD ($) $ / shares
Multiple of Equity Value at Issuance, 5x
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Per share common stock price required for payment \| $ / shares	$ 20.00
Success payment(s) \| $	$ 5.0
Multiple of Equity Value at Issuance, 10x
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Per share common stock price required for payment \| $ / shares	$ 40.00
Success payment(s) \| $	$ 15.0
Multiple of Equity Value at Issuance, 20x
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Per share common stock price required for payment \| $ / shares	$ 80.00
Success payment(s) \| $	$ 30.0
Multiple of Equity Value at Issuance, 30x
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Per share common stock price required for payment \| $ / shares	$ 120.00
Success payment(s) \| $	$ 50.0
Multiple of Equity Value at Issuance, 40x
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Per share common stock price required for payment \| $ / shares	$ 160.00
Success payment(s) \| $	$ 75.0

Restricted Cash - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Restricted Cash And Cash Equivalents [Abstract]
Standby letters of credit	$ 8,819	$ 2,143
Restricted cash and cash equivalents, noncurrent, nature of restriction, description	standby letters of credit

Restricted Cash - Summary of Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash	$ 8,819	$ 2,143
Fremont, CA
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash	6,676
Cambridge, MA
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash	961	961
South San Francisco, CA
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash	816	816
Seattle, WA
Restricted Cash And Cash Equivalents Items [Line Items]
Total restricted cash	$ 366	$ 366

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Cash Equivalents
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	$ 227,016	$ 90,224
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses		(1)
Estimated Fair Value	227,016	90,224
Cash Equivalents \| Money Market Funds \| Level 1
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	224,671	48,359
Estimated Fair Value	224,671	48,359
Cash Equivalents \| Corporate Debt Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	2,345	1,138
Estimated Fair Value	2,345	1,138
Cash Equivalents \| US Government and Agencies Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost		40,727
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses		(1)
Estimated Fair Value		40,727
Short-term Marketable Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	298,295	253,435
Gross Unrealized Holding Gains	1	30
Gross Unrealized Holding Losses	(329)	(7)
Estimated Fair Value	297,967	253,458
Short-term Marketable Securities \| Corporate Debt Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	135,441	8,798
Gross Unrealized Holding Losses	(134)	(2)
Estimated Fair Value	135,307	8,796
Short-term Marketable Securities \| US Government and Agencies Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	162,854	244,637
Gross Unrealized Holding Gains	1	30
Gross Unrealized Holding Losses	(195)	(5)
Estimated Fair Value	162,660	244,662
Long-term Marketable Securities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	196,919	33,724
Gross Unrealized Holding Gains		7
Gross Unrealized Holding Losses	(1,038)
Estimated Fair Value	195,881	33,731
Long-term Marketable Securities \| Corporate Debt Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	20,427
Gross Unrealized Holding Losses	(113)
Estimated Fair Value	20,314
Long-term Marketable Securities \| US Government and Agencies Securities \| Level 2
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	176,492	33,724
Gross Unrealized Holding Gains		7
Gross Unrealized Holding Losses	(925)
Estimated Fair Value	175,567	33,731
Other Assets \| Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	426
Estimated Fair Value	426
Financial Assets
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	722,656	377,383
Gross Unrealized Holding Gains	1	38
Gross Unrealized Holding Losses	(1,367)	(8)
Estimated Fair Value	721,290	377,413
Short-term Financial Liabilities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	56,382
Estimated Fair Value	56,382
Short-term Financial Liabilities \| Contingent consideration \| Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	51,382
Estimated Fair Value	51,382
Short-term Financial Liabilities \| Success Payment Liabilities \| Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	5,000
Estimated Fair Value	5,000
Long-term Financial Liabilities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	199,886
Estimated Fair Value	199,886
Long-term Financial Liabilities \| Contingent consideration \| Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	102,361	121,901
Estimated Fair Value	102,361	121,901
Long-term Financial Liabilities \| Success Payment Liabilities \| Level 3
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	97,525	76,494
Estimated Fair Value	97,525	76,494
Financial Liabilities
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Amortized Cost	256,268	198,395
Estimated Fair Value	$ 256,268	$ 198,395

Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Realized gains or losses recognized on sale or maturity of available-for-sale securities	$ 0
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities maturity period	2 years

Fair Value Measurements - Changes in Estimated Fair Value of Level 3 Financial Liabilities (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021
Contingent Consideration
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 131,981	$ 140,457	$ 133,294	$ 121,901
Changes in fair value - expense (gain)	21,762	(8,476)	7,163	11,393
Ending Balance	153,743	131,981	140,457	133,294
Cobalt Success Payment Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	111,609	89,819	156,451	64,694
Changes in fair value - expense (gain)	(23,256)	21,790	(66,632)	91,757
Ending Balance	88,353	111,609	89,819	156,451
Harvard Success Payment Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning Balance	22,583	19,144	35,700	11,800
Changes in fair value - expense (gain)	(8,411)	3,439	(16,556)	23,900
Ending Balance	$ 14,172	$ 22,583	$ 19,144	$ 35,700

Fair Value Measurements - Summary of Estimated Fair Value of Contingent Consideration Unobservable Inputs (Details)	Dec. 31, 2021	Dec. 31, 2020
Minimum \| Discount Rates
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.109	0.105
Minimum \| Probability of Milestone Achievement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.050	0.025
Maximum \| Discount Rates
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.1160	0.108
Maximum \| Probability of Milestone Achievement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.750	0.650
Weighted Average \| Discount Rates
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.112	0.106
Weighted Average \| Probability of Milestone Achievement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.338	0.276

Fair Value Measurements - Summary of Estimated Fair Value of Success Payment Liabilities Unobservable Inputs (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cobalt \| Expected Stock Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.70	0.70
Cobalt \| Expected Term (Years)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input expected term (years)	17 years 1 month 6 days	18 years 1 month 6 days
Harvard \| Expected Stock Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.70	0.70
Harvard \| Expected Term (Years)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input expected term (years)	9 years 2 months 12 days	10 years 2 months 12 days

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 84,238	$ 54,512
Less: Accumulated depreciation	(18,774)	(7,737)
Property and equipment, net	65,464	46,775
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, at cost	47,684	29,665
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, at cost	33,848	15,598
Construction In Progress
Property Plant And Equipment [Line Items]
Property and equipment, at cost	1,388	8,323
Computer Equipment, Software and Other
Property Plant And Equipment [Line Items]
Property and equipment, at cost	$ 1,318	$ 926

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 11,070	$ 5,921	$ 1,826

Accrued Liabilities - Schedule of Accrued Compensation and Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued compensation:
Accrued bonus	$ 13,814	$ 11,582
Accrued paid time off	4,429	2,441
Accrued payroll	2,888	1,997
Total accrued compensation	21,131	16,020
Accrued expenses and other current liabilities:
Accrued research and development expense services	3,419	1,197
Accrued property and equipment	2,566	2,892
Accrued professional fees	1,971	1,717
Other accrued current liabilities	2,388	3,660
Total accrued expenses and other current liabilities	$ 10,344	$ 9,466

Commitments and Contingencies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 Extension
Lessee Lease Description [Line Items]
Lease arrangement, contractual expiration period, beginning year	2024-04
Lease arrangement, contractual expiration period, ending year	2031-11
Weighted-average remaining lease term	9 years 10 months 17 days
Weighted-average incremental borrowing rate	9.15%
Seattle Operating Lease Agreement
Lessee Lease Description [Line Items]
Operating lease, renew period	5 years
Lessee, operating lease, existence of option to extend [true false]	true
Lessee, operating lease, option to extend	The Seattle and South San Francisco lease agreements each provide the Company with the option to renew for an additional period of five years.
South San Francisco Operating Lease Agreement
Lessee Lease Description [Line Items]
Operating lease, renew period	5 years
Lessee, operating lease, existence of option to extend [true false]	true
Lessee, operating lease, option to extend	The Seattle and South San Francisco lease agreements each provide the Company with the option to renew for an additional period of five years.
Fremont, CA
Lessee Lease Description [Line Items]
Operating lease, renew period	5 years
Lessee, operating lease, existence of option to extend [true false]	true
Lessee, operating lease, option to extend	option to extend for up to two additional five-year terms.
Lessee, operating lease, initial term	10 years
Fremont, CA \| Maximum
Lessee Lease Description [Line Items]
Number of additional extensions permitted	2

Commitments and Contingencies - Schedule of Additional Information Related to Operating Leases (Details)	12 Months Ended
	Dec. 31, 2021 ft²
Lessee Lease Description [Line Items]
Lease arrangement, contractual expiration period, beginning year	2024-04
Lease arrangement, contractual expiration period, ending year	2031-11
Seattle, WA
Lessee Lease Description [Line Items]
Approximate Square Footage	48,086
Commencement Dates, Beginning	2019-03
Commencement Dates, Ending	2020-09
Lease arrangement, contractual expiration period, beginning year	2026-12
Lease arrangement, contractual expiration period, ending year	2028-04
Cambridge, MA
Lessee Lease Description [Line Items]
Approximate Square Footage	59,639
Commencement Dates, Beginning	2019-03
Commencement Dates, Ending	2020-05
Lease arrangement, contractual expiration period, beginning year	2025-11
Lease arrangement, contractual expiration period, ending year	2028-02
South San Francisco, CA
Lessee Lease Description [Line Items]
Approximate Square Footage	66,075
Commencement Dates, Beginning	2019-12
Commencement Dates, Ending	2021-11
Lease arrangement, contractual expiration period, beginning year	2024-04
Lease arrangement, contractual expiration period, ending year	2030-04
Fremont, CA
Lessee Lease Description [Line Items]
Approximate Square Footage	163,193
Commencement Dates, Beginning	2021-07
Lease arrangement, contractual expiration period, ending year	2031-11

Commitments and Contingencies - Summary of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lease, Cost [Abstract]
Operating lease cost	$ 16,425	$ 10,757	$ 4,898
Short-term lease cost	512	1,886	3,710
Variable lease cost	5,230	3,081	1,494
Total lease cost	$ 22,167	$ 15,724	$ 10,102

Commitments and Contingencies - Reconciliation of Undiscounted Operating Lease Cash Flows by Fiscal Year to Present Value of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2022	$ 19,954
2023	21,511
2024	20,601
2025	20,449
2026	17,701
2026 and thereafter	80,913
Total undiscounted lease payments	181,129
Less: imputed interest	(66,291)
Less: tenant improvement allowances	(3,895)
Present value of operating lease liabilities	$ 110,943

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2021
Class Of Stock [Line Items]
Convertible preferred stock shares issued		134,113,000			0
Gross proceeds from issuance of convertible preferred stock		$ 435,538	$ 223,739
Capital stock, shares authorized		707,000,000.0
Capital stock par value		$ 0.0001
Convertible preferred stock, shares authorized		537,786,000			0
Common Stock
Class Of Stock [Line Items]
Common stock, shares authorized		169,200,000
Series A-1 Convertible Preferred Stock
Class Of Stock [Line Items]
Share issue price				$ 4.00
Convertible preferred stock shares issued				67,500,000
Gross proceeds from issuance of convertible preferred stock				$ 269,900
Series A-2 Convertible Preferred Stock
Class Of Stock [Line Items]
Share issue price			$ 4.00
Convertible preferred stock shares issued			67,500,000
Gross proceeds from issuance of convertible preferred stock			$ 269,900
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Share issue price	$ 16.00
Convertible preferred stock shares issued	27,200,000
Gross proceeds from issuance of convertible preferred stock	$ 435,500

Stockholders' Equity - Additional Information (Details) - shares	Dec. 31, 2021	Feb. 28, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Shares authorized		800,000,000.0
Common stock, shares authorized	750,000,000	750,000,000.0	707,000,000
Preferred stock, shares authorized	50,000,000	50,000,000.0	0
Common stock, shares outstanding	184,929,000		16,170,000
Restricted Stock
Class Of Stock [Line Items]
Common stock outstanding	4,365,000		10,079,000

Stock-Based Compensation - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Feb. 28, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2022
2021 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of shares of common stock reserved for issuance expressed as percentage of outstanding shares	5.00%
Number of shares available for future issuance	13.2
2021 Incentive Award Plan \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future issuance					9.5
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future issuance		1.9
Percentage related to employees able to purchase shares at lower of fair market value	85.00%
Percentage of annual increase in shares available for issuance	1.00%
Specify offering period	27 months
Number of shares determined by the board of directors	27.9
2021 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage allowed for eligible employees to purchase shares of common stock	15.00%
2021 Employee Stock Purchase Plan \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future issuance					1.9
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of vested		$ 1.5	$ 1.5	$ 1.0
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of vested		$ 4.1

Stock-Based Compensation - Schedule of Stock Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 22,362	$ 5,828	$ 1,497
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	15,239	4,888	1,246
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 7,123	$ 940	$ 251

Stock-Based Compensation - Schedule of Unrecognized Stock-Based Compensation Costs Related to Unvested Awards and Weighted-Average Period Over Which Costs are Expected to be Recognized (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense (in thousands)	$ 81,140
Weighted-average period costs expected to be recognized (in years)	3 years 2 months 12 days
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense (in thousands)	$ 1,892
Weighted-average period costs expected to be recognized (in years)	1 year 6 months
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense (in thousands)	$ 1,220
Weighted-average period costs expected to be recognized (in years)	1 year 6 months

Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Stock Options
Stock Options Outstanding, Beginning Balance \| shares	15,677
Stock Options, Granted \| shares	4,165
Stock Options, Exercised \| shares	(1,586)
Stock Options, Forfeited/Cancelled \| shares	(919)
Stock Options Outstanding, Ending Balance \| shares	17,337
Stock Options Exercisable \| shares	3,215
Weighted-Average Exercise Price per Share
Weighted-Average Exercise Price per Share Outstanding, Beginning Balance \| $ / shares	$ 4.52
Weighted-Average Exercise Price per Share, Granted \| $ / shares	22.57
Weighted-Average Exercise Price per Share, Exercised \| $ / shares	2.00
Weighted-Average Exercise Price per Share, Forfeited/Cancelled \| $ / shares	6.88
Weighted-Average Exercise Price per Share Outstanding, Ending Balance \| $ / shares	8.96
Weighted-Average Exercise Price Per Share Exercisable \| $ / shares	$ 2.61
Weighted-Average Remaining Contractual Life (years)
Weighted-Average Remaining Contractual Life (years), Outstanding	8 years 8 months 12 days
Weighted-Average Remaining Contractual Life (years), Exercisable	8 years 1 month 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding \| $	$ 141,718
Aggregate Intrinsic Value, Exercisable \| $	$ 41,382

Stock-Based Compensation - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model for Estimating Fair Value of Stock Options Granted (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk free interest rate, minimum	0.46%	0.36%	1.53%
Risk free interest rate, maximum	1.38%	1.51%	2.62%
Expected volatility	70.00%	70.00%	70.00%
Expected dividend	0.00%	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months	6 years 3 months	6 years 7 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 4 months 24 days	6 years 9 months	6 years 3 months

Stock-Based Compensation - Summary of Additional Information Related to Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Weighted average grant date fair value per share for options granted	$ 14.22	$ 3.52	$ 0.92
Aggregate intrinsic value of stock options exercised (in thousands)	$ 29,880	$ 605	$ 25

Stock-Based Compensation - Summary of RSA and RSU Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2021 $ / shares shares
RSAs
RSAs
Unvested shares as of December 31, 2020 \| shares	10,079
Vested \| shares	(5,691)
Forfeited \| shares	(23)
Unvested shares as of December 31, 2021 \| shares	4,365
Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2020 \| $ / shares	$ 0.33
Vested \| $ / shares	0.25
Forfeited \| $ / shares	1.00
Unvested shares as of December 31, 2021 \| $ / shares	$ 0.43
RSUs
RSAs
Unvested shares as of December 31, 2020 \| shares	326
Granted \| shares	57
Vested \| shares	(225)
Forfeited \| shares	(17)
Unvested shares as of December 31, 2021 \| shares	141
Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2020 \| $ / shares	$ 1.44
Granted \| $ / shares	21.37
Vested \| $ / shares	1.44
Forfeited \| $ / shares	1.44
Unvested shares as of December 31, 2021 \| $ / shares	$ 9.43

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2019	Dec. 31, 2020	Feb. 28, 2019
Income Taxes [Line Items]
Net operating loss carryforwards, federal	$ 101,900
Net operating loss carryforwards, state	12,400
Deferred tax liability	$ 23,039		$ 22,870
Deferred income tax		$ (7,547)
Cobalt Biomedicine Inc
Income Taxes [Line Items]
Deferred tax liability				$ 7,500
Deferred income tax		$ 7,500
State
Income Taxes [Line Items]
Net tax operating losses, expiration	begin to expire in 2038
Tax credit carryforward, expiration	begin to expire in 2038
Research tax credits	$ 6,500
Federal
Income Taxes [Line Items]
Research tax credits	$ 17,500

Income Taxes - Reconciliation of Income Taxes Computed Using U.S Federal Statutory Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Federal statutory tax	21.00%	21.00%	21.00%
State income tax, net of federal benefit	2.75%	2.09%	3.06%
Valuation allowance	(24.06%)	(15.18%)	(16.32%)
Success payment liabilities	(1.40%)	(4.58%)
Contingent consideration	(1.88%)	(3.89%)	(2.71%)
Tax credits	2.58%	1.88%	1.93%
Other	1.01%	(1.32%)	(1.50%)
Effective income tax rate	0.00%	0.00%	5.46%

Income Taxes - Components of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 114,368	$ 58,527
Lease liabilities	25,754	16,971
Tax credit carryforwards	24,008	11,908
Intangibles	5,986
Accrued liabilities and allowances	4,401	3,643
Success payment liabilities	3,290	2,785
Stock-based compensation	1,854
Other		25
Gross deferred tax assets	179,661	93,859
Valuation allowance	(156,622)	(70,989)
Deferred tax assets, net of valuation allowance	23,039	22,870
Deferred tax liabilities:
Right-of-use assets	(21,940)	(14,577)
Fixed assets	(1,050)	(935)
Intangibles		(6,870)
Stock-based compensation		(488)
Other	(49)
Deferred tax liabilities	$ (23,039)	$ (22,870)

Net Loss Per Share - Summary of Calculation of Basic and Diluted Net Loss Per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (355,928)	$ (285,305)	$ (130,778)
Weighted-average number of common shares - basic and diluted	166,433	13,014	4,903
Net loss per common share - basic and diluted	$ (2.14)	$ (21.92)	$ (26.68)

- Definition

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

+ References

+ Details

Net Loss Per Share - Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of dilutive net loss per share	21,843	160,195	127,924
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of dilutive net loss per share		134,113	106,890
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of dilutive net loss per share	17,337	15,677	3,549
Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of dilutive net loss per share	4,365	10,079	17,140
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of dilutive net loss per share	141	326	345

Employee Benefit Plan - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021 USD ($)
Compensation And Retirement Disclosure [Abstract]
Matching contribution by employer under retirement and savings plan	$ 0