Intellia Therapeutics (NTLA) 10-K 24 Feb 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Feb. 17, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Trading Symbol	NTLA
Entity Registrant Name	INTELLIA THERAPEUTICS, INC.
Entity Central Index Key	0001652130
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Interactive Data Current	Yes
Entity File Number	001-37766
Entity Tax Identification Number	36-4785571
Entity Address, Address Line One	40 Erie Street
Entity Address, Address Line Two	Suite 130
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	857
Local Phone Number	285-6200
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Document Annual Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		74,672,427
Entity Public Float			$ 10,925,830,738
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Part III of this Annual Report on Form 10-K incorporates by reference certain information from the registrant’s definitive Proxy Statement for its 2022 annual meeting of shareholders, which the registrant intends to file pursuant to Regulation 14A with the Securities and Exchange Commission not later than 120 days after the registrant’s fiscal year end of December 31, 2021. Except with respect to information specifically incorporated by reference in this Form 10-K, the Proxy Statement is not deemed to be filed as part of this Form 10-K.
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 123,406	$ 160,020
Marketable securities	625,282	437,351
Accounts receivable	2,031	2,130
Prepaid expenses and other current assets	18,584	17,016
Total current assets	769,303	616,517
Marketable securities - noncurrent	337,361	0
Property and equipment, net	20,968	15,943
Operating lease right-of-use assets	79,143	39,114
Equity method investment	58,131	0
Investments and other assets	29,558	4,748
Total Assets	1,294,464	676,322
Current Liabilities:
Accounts payable	9,653	10,460
Accrued expenses	43,309	25,554
Current portion of operating lease liability	9,112	5,696
Current portion of deferred revenue ($41.2 million and $0 million from related party)	63,759	22,544
Total current liabilities	125,833	64,254
Deferred revenue, net of current portion ($19.9 million and $0 million from related party)	63,476	51,387
Long-term operating lease liability	64,911	33,609
Commitments and contingencies (Note 8)
Stockholders’ Equity:
Common stock, $0.0001 par value; 120,000,000 shares authorized; 74,485,883 and 66,234,056 shares issued and outstanding at December 31, 2021 and 2020, respectively	7	7
Additional paid-in capital	1,745,870	962,173
Accumulated other comprehensive income	(2,632)	1
Accumulated deficit	(703,001)	(435,109)
Total stockholders’ equity	1,040,244	527,072
Total Liabilities and Stockholders’ Equity	$ 1,294,464	$ 676,322

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accounts receivable, related party	$ 0.1	$ 0
Investments and other assets, related party	10	0
Current portion of deferred revenue, related party	41.2	0
Deferred revenue, net of current portion, related party	$ 19.9	$ 0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	74,485,883	66,234,056
Common stock, shares outstanding	74,485,883	66,234,056

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Collaboration revenue	[1]	$ 33,053	$ 57,994	$ 43,103
Type of Revenue [Extensible List]		us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development		$ 229,807	$ 150,408	$ 108,413
General and administrative		71,096	44,169	41,058
Total operating expenses		300,903	194,577	149,471
Operating loss		(267,850)	(136,583)	(106,368)
Loss from equity method investments		1,325	0	0
Interest income		1,283	2,352	6,835
Total other (expense) income, net		42	2,352	6,835
Net loss		$ (267,892)	$ (134,231)	$ (99,533)
Net loss per share, basic and diluted		$ (3.78)	$ (2.40)	$ (2.11)
Weighted average shares outstanding, basic and diluted		70,894	55,987	47,247
Other comprehensive (loss) income:
Marketable Securities, Unrealized Gain (Loss), Total		$ (2,126)	$ (260)	$ 289
Other comprehensive loss from equity method investment		(507)	0	0
Comprehensive loss		$ (270,525)	$ (134,491)	$ (99,244)
[1]	(1) Including the following revenue from related party (see Notes 9 and 15): $ 6,072 $ - $ -

Consolidated Statements of Op_2

Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Revenue from Related Parties	$ 6,072	$ 0	$ 0

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
At The Market Offerings
Stock issuance cost	$ 52	$ 151	$ 36,300
Follow-on Offering [Member]
Stock issuance cost	$ 284	$ 669

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Follow On Public Offering	At The Market Offerings	Regeneron Pharmaceuticals Inc. [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Follow-on Offering [Member]	Follow-on Offering [Member]Follow On Public Offering	Follow-on Offering [Member]At The Market Offerings	Follow-on Offering [Member]Regeneron Pharmaceuticals Inc. [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]Follow On Public Offering	Additional Paid-In Capital [Member]At The Market Offerings	Additional Paid-In Capital [Member]Regeneron Pharmaceuticals Inc. [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning balance at Dec. 31, 2018	$ 277,920					$ 5				$ 478,968				$ (28)	$ (201,025)
Beginning balance (ASC 842 [Member]) at Dec. 31, 2018					$ (320)											$ (320)
Beginning balance, shares at Dec. 31, 2018						45,224,480
Issuance of common stock			$ 72,256									$ 72,256
Issuance of common stock, shares								4,518,579
Exercise of stock options	3,086									3,086
Exercise of stock options, shares						364,404
Issuance of shares under employee stock purchase plan	1,092									1,092
Issuance of shares under employee stock purchase plan, shares						90,581
Equity-based compensation	15,091									15,091
Equity-based compensation, shares						0
Other comprehensive income - unrealized gain (loss) on marketable securities	289													289
Net loss	(99,533)														(99,533)
Ending balance at Dec. 31, 2019	269,881					$ 5				570,493				261	(300,878)
Ending balance, shares at Dec. 31, 2019						50,198,044
Issuance of common stock		$ 296,607	49,461	$ 12,580			$ 2				$ 296,605	49,461	$ 12,580
Issuance of common stock, shares							11,815,069	2,270,161	925,218
Exercise of stock options	11,574									11,574
Exercise of stock options, shares						840,824
Vesting of restricted stock units, shares						82,829
Issuance of shares under employee stock purchase plan	1,557									1,557
Issuance of shares under employee stock purchase plan, shares						101,911
Equity-based compensation	19,903									19,903
Other comprehensive income - unrealized gain (loss) on marketable securities	(260)													(260)
Net loss	(134,231)														(134,231)
Ending balance at Dec. 31, 2020	$ 527,072					$ 7				962,173				1	(435,109)
Ending balance, shares at Dec. 31, 2020	66,234,056					66,234,056
Issuance of common stock		$ 648,315	$ 45,255								$ 648,315	$ 45,255
Issuance of common stock, shares							4,758,620	641,709
Exercise of stock options	$ 41,094									41,094
Exercise of stock options, shares	2,700,886					2,700,886
Vesting of restricted stock units, shares						119,715
Issuance of shares under employee stock purchase plan	$ 2,024									2,024
Issuance of shares under employee stock purchase plan, shares						30,897
Equity-based compensation	47,009									47,009
Other comprehensive income - unrealized gain (loss) on marketable securities	(2,126)													(2,126)
Other comprehensive loss - equity method investment	(507)													(507)
Net loss	(267,892)
Ending balance at Dec. 31, 2021	$ 1,040,244					$ 7				$ 1,745,870				$ (2,632)	$ (703,001)
Ending balance, shares at Dec. 31, 2021	74,485,883					74,485,883

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (267,892)	$ (134,231)	$ (99,533)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,891	6,311	5,587
Equity-based compensation	47,009	19,903	15,091
Amortization/(accretion) of investment premiums/(discounts)	7,604	538	3,725
Loss from equity method investments	1,325	0	0
Deferral of equity method investment intra-entity profit on sales	2,937	0	0
Loss on disposal of property and equipment	0	35	1
Changes in operating assets and liabilities:
Accounts receivable	99	2,490	2,927
Prepaid expenses and other current assets	(9,798)	(9,206)	(1,763)
Operating lease right-of-use assets	9,349	6,457	5,728
Other assets	117	83	153
Accounts payable	529	5,060	1,880
Accrued expenses	17,260	13,031	2,310
Deferred revenue	(31,355)	45,121	(27,122)
Operating lease liabilities	(9,105)	(5,504)	(4,774)
Net cash used in operating activities	(225,030)	(49,912)	(103,240)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(12,756)	(3,585)	(6,794)
Purchases of marketable securities	(1,020,620)	(473,702)	(297,030)
Maturities of marketable securities	485,598	262,800	329,000
Investment in Kyverna Therapeutics, Inc.	(3,000)	0	0
Net cash (used in) provided by investing activities	(550,778)	(214,487)	25,176
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	1,817,900
Proceeds from options exercised	41,094	11,574	3,086
Issuance of shares through employee stock purchase plan	2,024	1,557	1,092
Net cash provided by financing activities	736,688	371,779	76,434
Net (decrease) increase in cash and cash equivalents and restricted cash equivalents	(39,120)	107,380	(1,630)
Cash and cash equivalents and restricted cash equivalents, beginning of period	164,606	57,226	58,856
Cash and cash equivalents and restricted cash equivalents, end of period	125,486	164,606	57,226
Reconciliation of cash, cash equivalents and restricted cash equivalents to consolidated balance sheet:
Cash and cash equivalents	123,406	160,020	57,226
Restricted cash equivalents, included in investments and other assets	2,080	4,586	0
Cash and cash equivalents and restricted cash equivalents, end of period	125,486	164,606	57,226
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Purchases of property and equipment unpaid at period end	667	1,508	800
Right-of-use assets acquired under operating leases	49,378	26,432	2,554
Regeneron Pharmaceuticals Inc. [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	0	12,580	0
AvenCell Therapeutics, Inc [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Loss from equity method investments	2,900
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property	62,900	0	0
Sparing Vision SAS [Member]
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property	14,759	0	0
Kyverna Therapeutics, Inc. [Member]
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property	7,000	0	0
Follow On Public Offering
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	648,315	296,607	0
At The Market Offerings
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	$ 45,255	$ 49,461	$ 72,256

The Company

The Company	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	1. The Company Intellia Therapeutics, Inc. (“Intellia” or the “Company”) is a leading clinical-stage genome editing company, focused on developing novel, potentially curative CRISPR/Cas9-based therapeutics. CRISPR/Cas9, an acronym for C lustered, R egularly I nterspaced S hort P alindromic R epeats (“CRISPR”)/CRISPR associated 9 (“Cas9”), is a technology for genome editing, the process of altering selected sequences of genomic deoxyribonucleic acid (“DNA”). To realize the transformative potential of CRISPR/Cas9-based technologies, Intellia is building a full-spectrum genome editing company, by leveraging its modular platform, to advance in vivo and ex vivo therapies for diseases with high unmet need. For the Company's in vivo programs to address genetic diseases, intravenously administered CRISPR is used as the therapy, in which the Company's proprietary delivery technology enables highly precise editing of disease-causing genes directly within specific target tissues. For the Company's ex vivo programs to address immuno-oncology and autoimmune diseases, CRISPR is used to create the therapy by engineering cells outside of the body. The Company's deep scientific, technical and clinical development experience, along with its robust intellectual property (“IP”) portfolio, enables it to unlock broad therapeutic applications of CRISPR/Cas9 and related technologies to create new classes of genetic medicine. The Company was founded and commenced active operations in mid-2014. The Company will require substantial additional capital to fund its research and development. The Company is subject to risks and uncertainties common to early stage companies in the biotechnology industry, including, but not limited to, development by competitors of more advanced or effective therapies, dependence on key executives, protection of and dependence on proprietary technology, compliance with government regulations and ability to secure additional capital to fund operations. Programs currently in development or moving into development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Liquidity Since its inception through December 31, 2021, the Company has raised an aggregate of $ 1,817.9 million to fund its operations through its initial public offering (“IPO”) and concurrent private placements, follow-on public offerings, at-the-market offerings and the sale of convertible preferred stock, as well as through its collaboration agreements. The Company expects that its cash, cash equivalents and marketable securities as of December 31, 2021 will enable the Company to fund its ongoing operating expenses and capital expenditure requirements for at least the twelve-month period following the issuance of these consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements include the accounts of Intellia Therapeutics, Inc. and its wholly owned, controlled subsidiary, Intellia Securities Corp. All intercompany balances and transactions have been eliminated in consolidation. Comprehensive loss is comprised of net loss and gain/loss on marketable securities and equity method investments. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires management to make estimates, judgments and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates in these consolidated financial statements have been made in connection with the calculation of revenues, research and development expenses, valuation of equity and fair value method investments, and equity-based compensation expense. The Company bases its estimates on historical experience and various other assumptions that management believes to be reasonable under the circumstances at the time such estimates are made. Actual results could differ from those estimates. The Company periodically reviews its estimates in light of changes in circumstances, facts and experience. The extent of the impact of the coronavirus disease 19 (“COVID-19”) pandemic on the Company’s operational and financial performance will depend on certain developments, including the length and severity of this pandemic, as well as its effect on the Company's employees, collaborators and vendors, all of which are uncertain and cannot be predicted. The Company cannot reasonably estimate the extent to which the disruption may materially impact its consolidated results of operations or financial position. The effects of material revisions in estimates are reflected in the consolidated financial statements prospectively from the date of the change in estimate. Fair Value Measurements The Company’s financial instruments include cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. Certain of the Company’s financial assets, including cash equivalents and marketable securities, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third-party pricing services or other observable market data. The pricing services utilize industry standard valuation models and observable market inputs to determine value. Refer to Note 4 for further information regarding the Company’s fair value measurements. Other financial instruments, including accounts receivable, accounts payable and accrued expenses, are carried at cost, which approximate fair value due to the short duration and term to maturity. Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. As of December 31, 2021 and 2020, cash equivalents consisted of interest-bearing money market accounts. Restricted Cash Equivalents The Company has restricted cash equivalents made up of money market funds held in collateral accounts that are restricted to secure letters of credit in accordance with the leases for 281 Albany Street and 17 Tudor Street, which the Company entered into in March of 2020 and July of 2021, respectively (see Note 11). The letters of credit, in the amount of $ 1.9 million and $ 0.2 million, respectively, are required to be maintained throughout the term of the leases. These restricted cash equivalents are long-term in nature and are included in “Investments and other assets” in the Company’s consolidated balance sheets. The Company has also received funds from certain grants that were restricted as to their use and were therefore classified as restricted cash equivalents. These funds amounted to approximately $ 2.7 million as of December 31, 2020 and were used in full prior to December 31, 2021. Accordingly, these funds were included in “Prepaid expenses and other current assets” in the Company’s consolidated balance sheet for the period ended December 31, 2020. Marketable Securities The Company’s marketable securities are accounted for as available-for-sale and recorded at fair value with the related unrealized gains and losses included in accumulated other comprehensive (loss)/income, a component of stockholders’ equity. The Company reviews its investment portfolio to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. Refer to Note 3 for further information regarding the Company’s marketable securities. Non-Marketable Equity Securities The Company also invests in equity securities of companies whose securities are not publicly traded and where fair value is not readily available. These investments are accounted for using the measurement alternative at cost minus impairment adjusted for changes in observable prices. The Company monitors these investments to evaluate whether any increase or decline in their value has occurred, based on the implied value of recent company financings and general market conditions, or if the investment has a readily determinable fair value. These investments are included in “Investments and other assets” in the Company’s consolidated balance sheets. Refer to Note 10 for further information regarding the Company’s investments in non-marketable equity securities. Concentrations of Credit Risk The Company’s cash, cash equivalents and marketable securities may potentially be subject to concentrations of credit risk. The Company generally maintains balances in various accounts in excess of federally insured limits with financial institutions that management believes to be of high credit quality. Accounts receivable represents amounts due from collaboration partners and joint ventures. The Company monitors economic conditions to identify facts or circumstances that may indicate that any of its accounts receivable are at risk of collection. As of December 31, 2021, the Company’s accounts receivable were related to its collaborations with Regeneron Pharmaceuticals, Inc. (“Regeneron”) and AvenCell Therapeutics, Inc. (“AvenCell”), a new universal chimeric antigen receptor T (“CAR-T”) cell therapy joint venture and privately held company established by the Company, Cellex Cell Professionals GmbH (“Cellex”) and funds managed by Blackstone Life Sciences Advisors L.L.C. (“BXLS”) . As of December 31, 2020, Regeneron accounted for all of the Company’s accounts receivable. Property and Equipment The Company records property and equipment at cost and recognizes depreciation and amortization using the straight-line method over the following estimated useful lives of the respective assets: Asset Category Useful Life Laboratory equipment 5 years Office furniture and equipment 5 years Computer software 3 years Computer equipment 3 years Leasehold improvements 5 years or term of respective lease, if shorter Expenditures for repairs and maintenance of assets are expensed as incurred. Upon retirement or sale, the cost of assets disposed and the corresponding accumulated depreciation are removed from the related accounts and any resulting gain or loss is reflected in the results of operations. Impairment of Long-Lived Assets The Company tests long-lived assets to be held and used, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of assets or asset groups may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. Evaluation of recoverability of the asset or asset group is based on an estimate of undiscounted future cash flows resulting from the use of the asset or asset group and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the asset or asset group, the assets are written down to their estimated fair values. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. To date, the Company has not recorded any material impairment losses on long-lived assets. Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences attributable to differences between carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax reporting purposes and for operating loss and tax credit carryforwards. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company’s deferred tax assets and liabilities are measured using enacted tax rates expected to apply in the years in which these temporary differences are expected to be recovered or settled. A valuation allowance is recorded to reduce deferred tax assets if it is determined that it is more likely than not that all or a portion of the deferred tax asset will not be realized. The Company considers many factors when assessing the likelihood of future realization of deferred tax assets, including recent earnings results, expectations of future taxable income, carryforward periods available and other relevant factors. The Company records changes in the required valuation allowance in the period that the determination is made. The Company assesses its income tax positions and records tax benefits for all years subject to examination based upon management’s evaluation of the facts, circumstances and information available as of the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company records the largest amount of tax benefit with a greater than 50 % likelihood of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, the Company does not recognize a tax benefit in the financial statements. The Company records interest and penalties related to uncertain tax positions, if applicable, as a component of income tax expense. Revenue Recognition The Company recognizes revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) and its related amendments (collectively known as Accounting Standard Codification (“ASC”) 606 (“ASC 606”). At inception, the Company determines whether contracts are within the scope of ASC 606 or other topics. For contracts that are determined to be within the scope of ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these goods and services. To achieve this core principle, the Company applies the following five steps: (i) identify the contract with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when the Company determines that collection of substantially all consideration for goods and services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct and are distinct in the context of the contract. To the extent a contract includes multiple promised goods and services, the Company applies judgment to determine whether promised goods and services are both capable of being distinct and distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation. The transaction price is determined based on the consideration to which the Company will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method, depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. Determining the transaction price requires significant judgment, which is discussed in further detail for each of the Company’s collaboration agreements in Note 9. In addition, none of the Company’s contracts as of December 31, 2021 contained a significant financing component. If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation. The consideration to be received is allocated among the separate performance obligations based on relative standalone selling prices. The Company typically determines standalone selling prices using an adjusted market assessment approach model. The Company satisfies performance obligations either over time or at a point in time. Revenue is recognized over time if either (i) the customer simultaneously receives and consumes the benefits provided by the entity’s performance, (ii) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced, or (iii) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. If the entity does not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring the control of a promised good or service to a customer. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. As of December 31, 2021, the Company’s only revenue recognized is related to collaboration agreements with third parties which are either within the scope of ASC 606, under which the Company licenses certain rights to its product candidates to third parties, or within the scope of ASC 808, Collaborative Arrangements (“ASC 808”) if it involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards with respect to the arrangement. For the collaboration arrangements under the scope of ASC 606, as discussed in further detail in Note 9, the terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront fees; development, regulatory, and commercial milestone payments; research and development funding payments; and royalties on the net sales of licensed products. Additionally, the terms of certain arrangements may include an equity interest in the other company. Each of these payments results in collaboration revenues, except for revenues from royalties on the net sales of licensed products, which are classified as royalty revenues. For arrangements within the scope of ASC 808, the terms of these arrangements typically include payments received or made under the cost sharing provisions which are recognized as a component of revenues in the consolidated statements of operations and comprehensive loss. Licenses of intellectual property: If the license to the Company’s IP is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from consideration allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the licenses. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. Milestone payments: At the inception of each arrangement that includes development milestone payments, the Company evaluates the probability of reaching the milestones and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur in the future, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received and therefore revenue recognized is constrained as management is unable to assert that a reversal of revenue would not be probable. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenues and earnings in the period of adjustment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on levels of sales, if the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaboration agreements. The Company receives payments from its customers based on billing schedules or upon the achievement of milestones established in each contract. The Company’s contract liabilities consist of deferred revenue. Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company satisfies its obligations under these arrangements. The Company also considers the nature and contractual terms of an arrangement and assesses whether the arrangement involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards with respect to the arrangement. If the Company is an active participant and is exposed to the significant risks and rewards with respect to the arrangement, the Company accounts for the arrangement under ASC 808 . Based on this consideration, the Company accounts for its co-development and co-promotion (“Co/Co”) Agreements with Regeneron and AvenCell under ASC 808. Because ASC 808 does not provide recognition and measurement guidance for collaborative arrangements, the Company has analogized to ASC 606. Refer to Note 9 for additional information regarding the Company’s collaboration agreements. Research and Development Expenses Research and development costs are expensed as incurred. Research and development expenses consist of expenses incurred in performing research and development activities, such as salaries, equity-based compensation and benefits of employees, allocated facility-related expenses, overhead expenses, license, sublicense and milestone fees, contract research, clinical trial costs, development and manufacturing services, and other related costs. The Company records payments made for research and development services prior to the services being rendered as prepaid expenses on the consolidated balance sheet and expenses them as the services are provided. Contracts for multi-year research and development services are recorded on a straight-line basis over each annual contractual period based on the total contractual fee when the services rendered are expected to be substantially equivalent over the term of the arrangement. The cost of obtaining licenses for certain technology or IP is recorded to research and development expense when incurred if the licensed technology or IP has not yet reached technological feasibility and has no alternative future use. Equity-Based Compensation The Company measures employee equity-based compensation based on the grant date fair value of the equity awards using the Black-Scholes option pricing model. Equity-based compensation expense is recognized on a straight-line basis over the requisite service period of the awards and is adjusted for pre-vesting forfeitures in the period in which the forfeitures occur. For equity awards that have a performance condition, the Company recognizes stock-based compensation expense using the accelerated attribution method, based on its assessment of the probability that the performance condition will be achieved. The Company classifies equity-based compensation expense in its consolidated statement of operations and comprehensive loss in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified. (Loss) Earnings per Share The Company calculates basic (loss) earnings per share by dividing net (loss) income for each respective period by the weighted average number of common shares outstanding for each respective period. The Company computes diluted (loss) earnings per share after giving consideration to the dilutive effect of stock options and unvested restricted stock that are outstanding during the period, except where such securities would be anti-dilutive. Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s one business segment is the development of genome editing-based therapies. All of the Company’s assets are held in the U.S. and all of the Company’s revenue has been generated in the U.S. Variable Interest Entity The Company evaluates at the inception of each arrangement, and whenever a reconsideration event occurs, whether an entity in which the Company holds an investment or in which the Company has other variable interests is considered a variable interest entity (“VIE”) in accordance with FASB ASC Topic 810, Consolidation (“ASC 810”). If the entity meets the criteria to qualify as a VIE, the Company assesses whether or not the Company is the primary beneficiary of that VIE based on a number of factors, including (i) which party has the power to direct the activities that most significantly affect the VIE’s economic performance, (ii) the parties’ contractual rights and responsibilities pursuant to any contractual agreements and (iii) which party has the obligation to absorb losses or the right to receive benefits from the VIE. If the Company is deemed the primary beneficiary of a VIE, the Company consolidates such entity and reflects the non-controlling interest of other beneficiaries of that entity. If the Company is not the primary beneficiary, no consolidation is necessary, and the Company accounts for the investment or other variable interest in accordance with applicable U.S. GAAP. Equity Method of Accounting In circumstances where the Company has the ability to exercise significant influence, but not control, over the operating and financial policies of an entity in which the Company has a common stock or in-substance common stock investment, the Company utilizes the equity method of accounting for recording related investment activity. In assessing whether the Company exercises significant influence, the Company considers the nature and magnitude of the investment, the voting and protective rights the Company holds, any participation in the governance of the other entity and other relevant factors such as the presence of a collaborative or other business relationship. Under the equity method of accounting, the Company’s investments are initially recorded at cost on the consolidated balance sheets. Upon recording an equity method investment, the Company evaluates whether there are basis differences between the carrying value and fair value of the Company’s proportionate share of the investee’s underlying net assets. Typically, the Company amortizes basis differences identified on a straight-line basis over the underlying assets’ estimated useful lives when calculating the attributable earnings or losses, excluding the basis differences attributable to in-process research and development (“IPR&D”) that has no alternative future use. If the Company is unable to attribute all of the basis difference to specific assets or liabilities of the investee, the residual excess of the cost of the investment over the proportional fair value of the investee’s assets and liabilities is considered to be Equity Method Goodwill and is recognized within the equity investment balance, which is tracked separately within the Company’s memo accounts. The Company subsequently records in the consolidated statements of operations and comprehensive loss its share of income or loss of the other entity within other income/expense. If the share of losses exceeds the carrying value of the Company’s investment, the Company will suspend recognizing additional losses and will continue to do so unless it commits to providing additional funding; however, if there are intra-entity profits this can cause the investment balance to go negative. The Company evaluates its equity method investments for impairment whenever events or changes in circumstance indicate that the carrying amounts of such investments may be impaired and considers qualitative and quantitative factors including the investee's financial metrics, product and commercial outlook and cash usage. If a decline in the value of an equity method investment is determined to be other than temporary, a loss is recorded in earnings in the current period and the investment is written down to fair value. At December 31, 2021, the Company accounted for its investment in AvenCell under the equity method of accounting and no impairment charges were recognized during the year ended December 31, 2021. Refer to Note 10 for further details. Recent Accounting Pronouncements – Adopted In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes . ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The Company adopted ASU 2019-12 on January 1, 2021. The adoption did not have a material effect on the Company’s consolidated financial statements .

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	The following table summarizes the Company’s available-for-sale marketable securities as of December 31, 2021 and 2020 at net book value: December 31, 2021 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government securities $ 301,493 $ - $ ( 1,016 ) $ 300,477 Financial institution debt securities 441,068 - ( 652 ) 440,416 Corporate debt securities 62,500 - ( 151 ) 62,349 Other asset-backed securities 159,707 - ( 306 ) 159,401 Total $ 964,768 $ - $ ( 2,125 ) $ 962,643 December 31, 2020 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government securities $ 245,666 $ 13 $ ( 11 ) $ 245,668 Financial institution debt securities 138,445 6 ( 8 ) 138,443 Corporate debt securities 41,765 3 ( 2 ) 41,766 Other asset-backed securities 11,474 1 ( 1 ) 11,474 Total $ 437,350 $ 23 $ ( 22 ) $ 437,351 The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. At December 31, 2021 and 2020, the balance in the Company’s accumulated other comprehensive (loss)/income was composed of activity related to the Company’s available-for-sale marketable securities and equity method investment. There were no material realized gains or losses in the years ended December 31, 2021, 2020 or 2019. The Company did not reclassify any amounts out of accumulated other comprehensive income during these periods. T he Company generally does not intend to sell any investments prior to recovery of their amortized cost basis for any investment in an unrealized loss position. As such, the Company has classified these losses as temporary in nature . The Company's available-for-sale securities that are classified as short-term marketable securities in the consolidated balance sheet mature within one year or less as of the balance sheet date. Available-for-sale securities that are classified as noncurrent in the consolidated balance sheet are those that mature after one year but within five years from the balance sheet date and that the Company does not intend to dispose of within the next twelve months. At December 31, 2021 and 2020, the Company did no t hold any investments that matured beyond five years of the balance sheet date.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The Company classifies fair value-based measurements using a three-level hierarchy that prioritizes the inputs used to measure fair value. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1, quoted market prices in active markets for identical assets or liabilities; Level 2, observable inputs other than quoted market prices included in Level 1, such as quoted market prices for markets that are not active or other inputs that are observable or can be corroborated by observable market data; and Level 3, unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities, including certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. As of December 31, 2021 and 2020, the Company’s financial assets recognized at fair value on a recurring basis consisted of the following: Fair Value as of December 31, 2021 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents and restricted cash equivalents $ 124,636 $ 124,636 $ - $ - Marketable securities: U.S. Treasury and other government securities 300,477 280,085 20,392 - Financial institution debt securities 440,416 - 440,416 - Corporate debt securities 62,349 - 62,349 - Other asset-backed securities 159,401 - 159,401 - Total marketable securities 962,643 280,085 682,558 - Total $ 1,087,279 $ 404,721 $ 682,558 $ - Fair Value as of December 31, 2020 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents and restricted cash equivalents $ 163,805 $ 163,805 $ - $ - Marketable securities: U.S. Treasury and other government securities 245,668 241,664 4,004 - Financial institution debt securities 138,443 - 138,443 - Corporate debt securities 41,766 - 41,766 - Other asset-backed securities 11,474 - 11,474 - Total marketable securities 437,351 241,664 195,687 - Total $ 601,156 $ 405,469 $ 195,687 $ - Certain of the Company’s financial assets, including cash equivalents and marketable securities, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third-party pricing services or other observable market data. The pricing services utilize industry standard valuation models and observable market inputs to determine value. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of December 31, 2021 or 2020. The Company's investment in AvenCell was recorded at fair value, determined according to Level 3 inputs in the fair value hierarchy described above. Refer to Note 10 for further details. The Company's investment in SparingVision SAS (“SparingVision”) was recorded at fair value, determined according to Level 3 inputs in the fair value hierarchy described above. The Company's investment in Kyverna Therapeutics, Inc. (“Kyverna”) was recorded at cost, which is representative of fair value. Refer to Note 10 for further details. The SparingVision and Kyverna investments (the “investments”) are included in “Investments and other assets” on the consolidated balance sheet. There were no changes in observable prices of these investments as of December 31, 2021.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following: December 31, 2021 2020 (In thousands) Laboratory equipment $ 39,840 $ 30,438 Office furniture and equipment 2,186 1,181 Computer equipment 1,318 1,076 Leasehold improvements 2,188 1,520 Computer software 1,550 1,059 Total property and equipment 47,082 35,274 Less: accumulated depreciation and amortization ( 26,114 ) ( 19,331 ) Property and equipment, net $ 20,968 $ 15,943 Depreciation and amortization expense was $ 6.9 million, $ 6.3 million and $ 5.6 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consisted of the following: December 31, 2021 2020 (In thousands) Employee compensation and benefits $ 20,359 $ 10,920 Accrued research and development 16,979 11,008 Accrued legal and professional expenses 3,100 1,876 Accrued other 2,871 1,750 Total accrued expenses $ 43,309 $ 25,554

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	7. Income Taxes The Company did not record net income tax benefits for the operating losses incurred during the periods presented due to the uncertainty of realizing a tax benefit from those losses. Accordingly, any benefit recorded related to these deferred tax assets was offset by a valuation allowance reflecting management’s conclusion that realization of those assets was not more likely than not. A reconciliation of the federal statutory income tax rate and the Company’s effective income tax rate is as follows: Year Ended December 31, 2021 2020 2019 Federal statutory income tax rate ( 21.0 )% ( 21.0 )% ( 21.0 )% State income taxes ( 16.6 ) ( 7.4 ) ( 8.9 ) Research and development tax credits ( 8.7 ) ( 1.8 ) ( 5.1 ) Stock-based compensation ( 16.8 ) ( 1.3 ) 1.2 162m 0.2 - - Change in valuation allowance 62.9 31.5 33.8 Effective income tax rate — % — % — % The Company’s net deferred tax assets (liabilities) consisted of the following: December 31, 2021 2020 (in thousands) Deferred tax assets: Intangibles, including acquired in-process $ 1,010 $ 981 Capitalized start-up costs 334 378 Net operating loss carryforwards 216,629 101,807 Research and development credit carryforwards 61,698 23,166 Operating lease liability 20,055 10,713 Deferred revenue 13,922 4,680 Equity-based compensation 7,774 8,574 Accruals and allowances 3,718 2,200 Prepaid rent 1,393 - Equity investment adjustments 359 - Gross deferred tax assets 326,892 152,499 Deferred tax asset valuation allowance ( 304,781 ) ( 140,868 ) Total deferred tax assets 22,111 11,631 Deferred tax liabilities: Fixed assets ( 669 ) ( 970 ) Operating lease right-of-use assets ( 21,442 ) ( 10,661 ) Total deferred tax liabilities ( 22,111 ) ( 11,631 ) Net deferred tax asset (liability) $ - $ - As of December 31, 2021 and 2020, the Company had federal net operating loss carryforwards of $ 800.5 million and $ 372.5 million, respectively, which may be available to offset future income tax liabilities. Approximately $ 37.2 million of the federal net operating losses generated prior to 2018 will begin to expire in 2034 , unless previously utilized. Losses incurred prior to 2018 will generally be deductible to the extent of the lesser of a corporation’s net operating loss carryover or 100 % of a corporation’s taxable income and be available for twenty years from the period the loss was generated. The federal net operating losses generated after 2017 of approximately $ 763.3 million will be carried over indefinitely, but will generally limit the net operating loss deduction to the lesser of the net operating loss carryforward or 80 % of a corporation’s taxable income (subject to Section 382 of the Internal Revenue Code of 1986, as amended). Also, there will be no carryback for losses incurred after 2017. On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act, (the “CARES Act”) was enacted in the U.S. The CARES Act temporarily removes the 80 % limit for taxable years beginning before 2021 to allow an net operating loss carryforward to fully offset an organization’s income. The CARES Act allows a five-year carryback of any net operating loss generated in a taxable year beginning after December 31, 2017, and before January 1, 2021. The impact of the CARES Act was not material to the Company. As of December 31, 2021 and 2020, the Company also had state net operating loss carryforwards of $ 767.8 million and $ 373.1 million, respectively, which may be available to offset future income tax liabilities and begin to expire in 2034 . As of December 31, 2021 and 2020, the Company had federal tax credit carryforwards of approximately $ 37.9 million and $ 15.0 million, respectively, which begin to expire in 2034 . As of December 31, 2021 and 2020, the Company had state research and development and other credit carryforwards of approximately $ 30.2 million and $ 10.3 million, which begin to expire in 2029 . The Company evaluated the expected realizability of its net deferred tax assets and determined that there was significant negative evidence due to its net operating loss position and insufficient positive evidence to support the realizability of these net deferred tax assets. The Company concluded it is more likely than not that its net deferred tax assets would not be realized in the future; therefore, the Company has provided a full valuation allowance against its net deferred tax asset balance as of December 31, 2021 and 2020. The valuation allowance increased by $ 163.9 million in 2021, $ 42.4 million in 2020, $ 34.5 million in 2019. Utilization of the net operating loss and research and development credit carryforwards may be subject to a substantial annual limitation under Section 382 of the Internal Revenue Code of 1986, as amended, due to ownership changes that have occurred previously or that could occur in the future. These ownership changes may limit the amount of net operating loss and research and development credit carryforwards that can be utilized annually to offset future taxable income and tax expense, respectively. The Company has not yet conducted a study to assess whether a change of control, as defined in Section 382, has occurred or whether there have been multiple changes in control since inception, due to the significant cost and complexity associated with such a study. Any limitation may result in expiration of a portion of the net operating loss carryforward or research credit carryforward before utilization. A full valuation allowance has been provided against the Company’s net operating loss and tax credit carryforwards and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations if an adjustment is required. As of December 31, 2021 , the Company had no t identified any unrecognized tax benefits. The Company files income tax returns in the U.S. federal tax jurisdiction and Massachusetts and various other state tax jurisdictions. The Company is subject to examination by the Internal Revenue Service, Massachusetts taxing authorities and state taxing authorities for tax year 2018 through present. The returns in these jurisdictions since inception remain open for examination; however, there are currently no pending tax examinations. The Company will recognize interest and/or penalties related to uncertain tax benefits in income tax expense if they arise.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Caribou Arbitration On October 17, 2018, the Company initiated an arbitration proceeding against Caribou Biosciences, Inc. (“Caribou”) asserting that Caribou violated the terms and conditions of a license agreement the Company entered into with them in July 2014 related to certain IP (the “Caribou License”), as well as other contractual and legal obligations to the Company, by using and seeking to license to third parties two patent families relating to specific structural or chemical modifications of guide RNAs (“gRNAs”), that were purportedly invented or controlled by Caribou, in the Company’s exclusive human therapeutic field, before an agreed-upon cutoff date of January 30, 2018. On September 26, 2019, the Company announced that the arbitration panel issued an interim award concluding that both the structural and chemical gRNA modification technologies were exclusively licensed to the Company by Caribou pursuant to the Caribou License. Nevertheless, the arbitration panel, solely with respect to the clinically modified gRNAs, stated that it will declare that Caribou has an equitable “leaseback”, which it described as exclusive, perpetual and worldwide (the “Caribou Award”). The Caribou Award does not include the structural guide modifications IP also at issue in the arbitration, any other IP exclusively licensed or sublicensed by Caribou to the Company under the Caribou License (including but not limited to the foundational CRISPR/Cas9 IP co-owned by the Regents of the University of California, University of Vienna and Dr. Emmanuelle Charpentier), or any other of the Company’s IP. On February 6, 2020, the panel clarified that the Caribou Award is limited to a particular on-going Caribou program, which seeks to develop a CAR-T product directed at CD19. On June 16, 2021, the Company executed a Leaseback Agreement (“Leaseback”) with Caribou, which settled the ongoing arbitration. Under the Leaseback negotiated by the parties, in exchange for an upfront payment, potential future regulatory and sales milestones, and single-digit royalties payable by Caribou, the Company has agreed to leaseback or sublicense certain CRISPR/Cas9 IP, including the Company’s chemical gRNA modification technology and foundational CRISPR/Cas9 IP, to Caribou so that it can develop and commercialize CB-010. Caribou also will be responsible for any payments required in respect of the Company’s in-licensed IP. The Company recorded $ 1.0 million within “Collaboration Revenue” in the second quarter of 2021 on the condensed consolidated statements of operations and comprehensive loss for an upfront payment related to the Leaseback and received the payment in the third quarter of 2021 . License Agreements The Company is party to license agreements, which include contingent payments. These payments will become payable if and when certain development, regulatory and commercial milestones are achieved. As of December 31, 2021, the satisfaction and timing of the contingent payments is uncertain and not reasonably estimable.

Collaborations

Collaborations	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations	9. Collaborations and Other Arrangements To accelerate the development and commercialization of CRISPR/Cas9-based products in multiple therapeutic areas, the Company has formed, and intends to seek other opportunities to form, strategic alliances with collaborators who can augment its leadership in CRISPR/Cas9 therapeutic development. As of December 31, 2021, the Company’s accounts receivable were related to its collaborations with Regeneron and AvenCell . As of December 31, 2021 the Company's contract liabilities were related to its collaborations with Regeneron, AvenCell, SparingVision and Kyverna. As of December 31, 2020, the Company’s accounts receivable and contract liabilities were related to the Company’s collaboration with Regeneron. The following table presents changes in the Company’s accounts receivable and contract liabilities during the years ended December 31, 2021 and 2020 (in thousands): Balance at Additions Deductions Balance at End Year Ended December 31, 2021 Accounts receivable $ 2,130 $ 7,559 $ ( 7,658 ) $ 2,031 Contract liabilities: Deferred revenue $ 73,931 $ 84,659 $ ( 31,355 ) $ 127,235 Balance at Additions Deductions Balance at End Year Ended December 31, 2020 Accounts receivable $ 4,620 $ 103,116 $ ( 105,606 ) $ 2,130 Contract liabilities: Deferred revenue $ 28,810 $ 87,477 $ ( 42,356 ) $ 73,931 During the years ended December 31, 2021 and 2020, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Revenue recognized in the period from: Year Ended Year Ended Amounts included in the contract liability at the beginning of the period $ 22,544 $ 11,571 Costs to obtain and fulfill a contract The Company did no t incur any expenses to obtain collaboration agreements and costs to fulfill those contracts do not generate or enhance resources of the Company. As such, no costs to obtain or fulfill a contract have been capitalized in any period. Regeneron Pharmaceuticals, Inc. In April 2016, the Company entered into a license and collaboration agreement with Regeneron (the “2016 Regeneron Agreement”). The 2016 Regeneron Agreement has two principal components: i) a product development component under which the parties will research, develop and commercialize CRISPR/Cas-based therapeutic products primarily focused on genome editing in the liver, and ii) a technology collaboration component, pursuant to which the Company and Regeneron will engage in research-related activities aimed at discovering and developing novel technologies and improvements to CRISPR/Cas technology to enhance the Company’s genome editing platform. Under this agreement, the Company also may access the Regeneron Genetics Center and proprietary mouse models to be provided by Regeneron for a limited number of the Company’s liver programs. At the inception of the 2016 Regeneron Agreement, Regeneron selected the first of its 10 targets, transthyretin (“ATTR”) amyloidosis, which is subject to a co-development and co-promotion agreement between the Company and Regeneron (the “ATTR Co/Co”). On May 30, 2020, the Company entered into (i) amendment no. 1 (the “2020 Regeneron Amendment”) to the 2016 Regeneron Agreement, (ii) co-development and co-funding agreements for the treatment of hemophilia A and hemophilia B (the “Hemophilia Co/Co”) agreements and (iii) a stock purchase agreement. The collaboration expansion builds upon the jointly developed targeted transgene insertion capabilities designed to durably restore missing therapeutic protein, and to overcome the limitations of traditional gene therapy. The collaboration was extended until April 2024, at which point Regeneron has an option to renew for an additional two years. The 2020 Regeneron Amendment also grants Regeneron exclusive rights to develop products for five additional in vivo CRISPR/Cas-based therapeutic liver targets and non-exclusive rights to independently develop and commercialize up to 10 ex vivo gene edited products made using certain defined cell types. Since December 31, 2020, there have been no material changes to the key terms of the 2016 Regeneron Agreement and the 2020 Regeneron Amendment (the “Amended Agreements”). For further information on the terms and conditions of these agreements, please see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2020. Revenue Recognition: Collaboration Revenue. Through December 31, 2021, excluding amounts allocated to Regeneron’s purchase of the Company’s common stock, the Company recorded $ 145.0 million in upfront payments under the Amended Agreements and $ 37.9 million for research and development services, primarily under the ATTR Co/Co agreement. Through December 31, 2021 , the Company has recognized $ 149.0 million of collaboration revenue under all arrangements, including $ 25.7 million, $ 53.0 million and $ 24.6 million of collaboration revenue in the years ended December 31, 2021, 2020 and 2019, respectively, in the consolidated statements of operations and comprehensive loss. This includes $ 5.9 million, $ 10.7 million, and $ 12.0 million, respectively, primarily representing payments due from Regeneron pursuant to the ATTR Co/Co agreement. These revenues are offset in part by contra-revenue related to the Hemophilia Co/Co agreements amounting to $ 2.7 million in the year ended December 31, 2021 and $ 0 million in the years ended December 31, 2020 and 2019. As of December 31, 2021, there was approximately $ 51.4 million of the aggregate transaction price of the Amended Agreements remaining to be recognized, which the Company expects to be recognized during the research term through April 2024. As of December 31, 2021 and 2020, the Company had accounts receivable of $ 2.0 million and $ 2.1 million, respectively, and deferred revenue of $ 51.4 million and $ 73.9 million, respectively, related to the Amended Agreements. AvenCell Therapeutics, Inc. On July 30, 2021 (the “Effective Date”), the Company entered into two agreements with AvenCell, a privately held CAR-T cell therapy company formed on that date in a joint venture between the Company, Cellex and BXLS: (i) a license and collaboration agreement (the “LCA”), under which the Company will collaborate to develop allogeneic universal CAR-T cell therapies and which granted AvenCell a license to develop and commercialize genome edited universal CAR-T cell therapies (limited to its use with their switchable, universal CAR-T cell UniCAR and RevCAR platforms); and (ii) a co-development and co-funding agreement (the “AvenCell Co/Co”), under which the Company will co-develop and co-commercialize allogeneic universal CAR-T cell products for an immuno-oncology indication. Scope: The Company granted AvenCell an exclusive license to combine the Company’s CRISPR/Cas9 technology platform with AvenCell’s switchable, universal CAR-T cell technology platform and made available to AvenCell certain know-how and materials. For an eighteen-month period after the Effective Date, the Company will provide to AvenCell any improvements with respect to the underlying technology that are developed. For the two-year period immediately following the Effective Date, the Company will perform certain activities, at the Company’s cost and expense, including providing to AvenCell certain know-how and materials to enable AvenCell to use the Company's CRISPR/Cas9 technology platform, as well as making available employees with requisite knowledge and experience to provide advice and answer questions regarding such know-how and materials for a limited number of hours per year (the “Knowledge Transfer Period”). In addition, the Company and AvenCell will collaborate on at least seven universal CAR-T ce ll products that combine the Company's allogeneic T cell technology with AvenCell's switchable, universal CAR-T cell technology, referred to as the (“Allo Collaboration”). AvenCell will pay the Company to provide supply and manufacturing services for them, including supplying GMP CRISPR reagents to support the research and development of all CRISPR Products (as defined in the LCA) under the Allo Collaboration until the completion of the first Pivotal Trial (as defined in the LCA) of the first such CRISPR Product. Financial Terms: In exchange for the license, the Company received a 33.33 % equity interest in AvenCell at the time of the initial closing and AvenCell is, therefore, considered to be a related party of the Company. Governance: The parties formed a joint steering committee (“JSC”), which is responsible for setting research objectives and overseeing the general strategies and research and development activities undertaken by the parties under the LCA. The JSC will meet quarterly until the expiration or termination of the Allo Collaboration. Term and Termination: The term of the Allo Collaboration is from the Effective Date of the LCA until the completion of all activities under the then-current Allo Collaboration with respect to all relevant CRISPR Products. The LCA contains termination provisions, including termination for insolvency, material breach, patent challenge, convenience, and cessation. Co-Development and Co-Promotion Agreement: Under the AvenCell Co/Co the parties will co-develop and co-commercialize in the U.S. and key European countries certain allogeneic universal CAR-T products directed to an immuno-oncology target. The Company is the lead commercialization party in the U.S., and AvenCell is the lead commercialization party in the European countries. The parties will share equally in the profits and development costs. The Company will have one additional option to enter into a second co-development and co-funding agreement from selected allogeneic universal CAR-T cell therapy products that the parties intend to develop under the Allo Collaboration for a payment of $ 30.0 million to AvenCell. AvenCell LCA - Accounting Analysis: The Company concluded that the accounting treatment for the LCA is within the scope of ASC 606 . The Company evaluated the promised goods and services under the LCA and determined that it included one performance obligation: a combined performance obligation including the license to the allogeneic technology, initial know-how and ongoing support services, including participation in the JSC during the two-year Knowledge Transfer Period. The transaction price was determined to be $ 62.9 million, which represents the fair value of the Company's equity interest in AvenCell as of the Effective Date. The Company allocated the full transaction price to the combined performance obligation including the license to allogeneic technology, the JSC, initial-know-how and ongoing support services. The Company will recognize the $62.9 million using a time elapsed input method over the Knowledge Transfer Period, which in management’s judgement is the best measure of progress towards satisfying the performance obligation as this method provides the most faithful depiction of the entity’s performance in transferring control of the goods and services promised to AvenCell. This represents the Company’s best estimate of the obligation, as after this period AvenCell will be able to fully benefit from the licensed IP on its own or with readily available resources. Revenue recorded during each period will be eliminated in part by an amount representing the Company's 33.33 % ownership interest in AvenCell at that time, as this represents the intra-entity profit related to the transaction. The Company will re-evaluate the measure of progress in each reporting period and, if necessary, adjust the measure of performance and related revenue recognition. The Company completed the initial transfer of know-how in the third quarter of 2021. The Company recognized $ 5.9 million in revenue related to the LCA for the year ended December 31, 2021 after eliminating $ 2.9 million in intra-entity profits, which will be deferred and recognized if and when AvenCell commercializes a product with the Company's license or abandons the related project. Until such time, the $ 2.9 million of revenue is indefinitely deferred and excluded from the results of operations of the Company. As of December 31, 2021 the Company had deferred revenue of $ 54.1 million related to the AvenCell LCA, which the Company expects to recognize through July 2023 . The payments attributable to the supply and manufacturing services are variable and are commensurate with the standalone selling prices of the services, and as such, will be attributed to those services. The Company did not record any consideration related to the supply and manufacturing services in 2021. AvenCell Co/Co - Accounting Analysis: The Company concluded that the AvenCell Co/Co agreement meets the definition of a collaborative arrangement per ASC 808, which is outside of the scope of ASC 606. Since ASC 808 does not provide recognition and measurement guidance for collaborative arrangements, the Company has analogized to ASC 606. As such, the Company classifies cumulative amounts paid or received under the cost sharing provisions of the AvenCell Co/Co as a component of revenues in the consolidated statements of operations and comprehensive loss, to the extent that this does not result in a cumulative “negative revenue” amount, in which case the cumulative shortfall would be reclassified as an expense. The Company recognized $ 0.2 million in revenues related to the AvenCell Co/Co agreement for the year ended December 31, 2021. SparingVision SAS In October 2021, the Company and SparingVision, a genomic medicine company developing vision saving treatments for ocular diseases, entered into a license and collaboration agreement (the “SparingVision LCA”), to develop novel genomic medicines utilizing CRISPR/Cas9 technology for the treatment of ocular diseases. Scope: The Company granted SparingVision exclusive rights to its proprietary in vivo CRISPR/Cas9-based genome editing technology for up to three ocular targets addressing diseases with significant unmet medical need. In addition, the parties will research and develop novel self-inactivating adeno-associated virus (“AAV”) vectors and lipid nanoparticle-based approaches to address delivery of CRISPR/Cas9 genome editing reagents to the retina. SparingVision will lead and fund the preclinical and clinical development for the genome editing product candidates pursued under the collaboration. The Company will have an option to obtain exclusive U.S. commercialization rights for product candidates arising from two of three collaboration targets. For product candidates the Company chooses to option, it will pay an opt-in fee between $ 10.0 million and $ 20.0 million depending on the stage of development of the target, reimburse certain costs, share in 50 % of development costs and pay royalties to SparingVision on U.S. sales. Financial Terms: In exchange for the license, the Company received 83,316 shares of Series A2 Preferred Stock (“Series A2”) which represented an equity ownership of approximately 11 % at the time of closing. Attached to each share of Series A2, the Company received three warrants for the right to purchase additional Series A2 shares at designated prices that are subject to certain vesting conditions. The Company will also be eligible to receive certain research, development and commercial milestone payments (up to approximately $ 200 million per product) as well as royalties on potential future sales of products arising from the collaboration. Governance : The parties formed a JSC, which is responsible for monitoring and managing the collaboration prior to program completion. SparingVision LCA - Accounting Analysis: The Company determined that the accounting for the SparingVision LCA is within the scope of ASC 606. The Company evaluated the promised goods and services and determined that it included one performance obligation: a combined performance obligation including the license to the CRISPR technology as well as ongoing research and support services, including participation in the JSC . The transaction price was determined to be $ 14.8 million, which represents the fair value of the Company's equity interest in SparingVision at the time of closing. See Note 10 for the determination of the fair value of the Company’s investment. The Company allocated the full transaction price to the combined performance obligation. The Company will use a costs-incurred input method to recognize revenue, measuring the progress of the programs based on the costs incurred against budget, which in management's judgment is the best measure of progress towards satisfying the performance obligation. These costs will be recorded as revenue when the expenses are incurred. There was no revenue recognized in the year ended December 31, 2021 related to the SparingVision LCA. As of December 31, 2021, the Company had deferred revenue of $ 14.8 million, which is expected to be recognized over a three to five year period. Kyverna Therapeutics, Inc. In December 2021, the Company and Kyverna, a cell therapy company engineering a new class of therapies for autoimmune and inflammatory diseases, entered into a licensing and collaboration agreement (the “Kyverna LCA”), for the development of an allogeneic CD19 CAR-T cell therapy for the treatment of a variety of B cell-mediated autoimmune diseases. Scope: The Company granted Kyverna rights to its proprietary ex vivo CRISPR/Cas9-based allogeneic platform for the development of KYV-201, an allogeneic CD19 CAR-T cell investigational candidate for the treatment of select autoimmune diseases. This is a novel approach aimed at targeting CD19 for inflammatory diseases as compared to traditional oncology indications. Kyverna will lead and fund preclinical and clinical development for KYV-201. The Company will have an option to lead U.S. commercialization for KYV-201 under a co-development and co-commercialization agreement. If the Company chooses to co-develop and co-commercialize KYV-201, it will pay an opt-in fee of $ 5.0 million and share in 50 % of development costs and future net profit and/or loss arising from commercializing KYV-201 in the U.S. Kyverna retains all rights outside of the U.S. , and the Company will receive low-to-mid-single-digit royalties on net sales generated outside of the U.S. Kyverna is considered to be a related party, as they have a board member in common with the Company. Financial Terms: In exchange for the license, the Company received an equity ownership of approximately 7% in Kyverna at the time of closing. The Company will be eligible to receive certain development and commercial milestone payments, as well as low-to-mid-single-digit royalties on potential future sales of KYV-201. Kyverna LCA – Accounting Analysis: The Company determined that the accounting for the Kyverna LCA is within the scope of ASC 606. The Company evaluated the promised goods and services and determined that it included one performance obligation: a combined performance obligation related to the transfer of the license related to the allogeneic platform technology, a technology transfer, and other supply and research and development activities. The transaction price was determined to be $ 7.0 million, which represents the fair value of the Company's equity interest in Kyverna at the time of closing. See Note 10 for the determination of the fair value of the Company's investment. The Company allocated the full transaction price to the combined performance obligation. Revenue will be recognized under a time-elapsed input model starting at the completion of the technology transfer, which in management's judgment is the best measure of progress towards satisfying the performance obligation. Progress will be measured and reassessed quarterly. There was no revenue recognized in the year ended December 31, 2021 related to the Kyverna LCA. As of December 31, 2021, the Company had deferred revenue of $ 7.0 million which is expected to be recognized over a nine to twelve month period. Novartis Institutes for BioMedical Research, Inc. In December 2014, the Company entered into a strategic collaboration agreement with Novartis (the “2014 Novartis Agreement”), primarily focused on the research of new ex vivo CRISPR/Cas9-edited therapies using CAR-T cells and hematopoietic stem cells (“HSCs”). The agreement was amended in December 2018 (the “Novartis Amendment”) to also include research on ocular stem cells (“OSCs”). In December 2019, per the terms of the 2014 Novartis Agreement, the research term ended, although the 2014 Novartis Agreement remains in effect, for which the Company will be eligible to receive milestone and royalty payments in the future. In June 2021, the Company entered into Amendment No. 3 (the “Amendment”) to the 2014 Novartis Agreement. The Amendment amends Novartis’ rights with respect to all of the CAR-T Therapeutic Targets (as defined in the 2014 Novartis Agreement) that Novartis selected under the 2014 Novartis Agreement, including (a) making Novartis’ license non-exclusive for such CAR-T Therapeutic Targets, (b) removing Novartis’ diligence and related reporting obligations for such CAR-T Therapeutic Targets, and (c) refining the scope of Novartis’ sublicense rights for such CAR-T Therapeutic Targets. The Company made a one-time payment to Novartis of $ 10.0 million within 30 days after the effective date of the Amendment, which was recorded as research and development expense in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2021. Since December 31, 2020, there have been no other material changes to the key terms of the 2014 Novartis Agreement and the Novartis Amendment. For further information on the terms and conditions of these agreements, please see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2020. Revenue Recognition – Collaboration Revenue. Through December 31, 2021, excluding amounts allocated to Novartis’ purchase of the Company’s Class A-1 and Class A-2 Preferred Units, the Company had recorded a total of $62.4 million in cash under the 2014 Novartis Agreement and the Novartis Amendment. Through December 31, 2021, the Company recognized $ 62.4 million of collaboration revenue. No revenue was recognized during the years ended December 31, 2021 or 2020 related to the 2014 Novartis Agreement and the Novartis Amendment. The Company recognized $ 18.5 million during the year ended December 31, 2019, in the consolidated statement of operations and comprehensive loss, related to the 2014 Novartis Agreement and the Novartis Amendment. As of December 31, 2019, the aggregate transaction price had been recognized in full. Revenue Recognition – Milestone . In March 2020, the U.S. Food and Drug Administration (“FDA”) accepted the Investigational New Drug ( “ IND ” ) application submitted by Novartis for a CRISPR/Cas9-based engineered cell therapy for the treatment of sickle cell disease. As a result of meeting this milestone, the Company recognized $ 5.0 million as collaboration revenue within the consolidated statement of operations and comprehensive loss. In September 2021, an additional milestone was reached and, as a result, the Company recognized $ 0.3 million as collaboration revenue within the consolidated statement of operations and comprehensive loss. No other milestones under the 2014 Novartis Agreement and the Novartis Amendment were achieved during the years ended December 31, 2021, 2020 or 2019. The Company is eligible to receive additional downstream success-based milestones and royalties. As of December 31, 2021 and 2020, the Company had no accounts receivable or deferred revenue related to the 2014 Novartis Agreement and the Novartis Amendment.

Equity-Method Investment

Equity-Method Investment	12 Months Ended
	Dec. 31, 2021
Equity Method Investments and Joint Ventures [Abstract]
Equity-Method Investment	10. Equity-Method Investment and Other Investments AvenCell Therapeutics, Inc. On July 30, 2021, the Company finalized a transaction in which the Company, Cellex and BXLS established AvenCell, a joint venture and privately held company. In exchange for contributing an exclusive license to the joint venture, the Company entered into a Preferred Stock Purchase Agreement with AvenCell for a 33.33 % equity interest in AvenCell at the time of the initial closing. Cellex and BXLS each equally owned the remaining 66.67 % at that time. The Company has significant influence over, but does not control, AvenCell through its noncontrolling representation on AvenCell’s Board of Directors and the Company’s equity interest in AvenCell. The Company has determined that the preferred stock it owns is in-substance common stock. The Company is not the primary beneficiary as it does not have the power to direct the activities of AvenCell that most significantly impact AvenCell’s economic performance. Accordingly, the Company does not consolidate the financial statements of AvenCell and accounts for its investment using the equity method of accounting. As of the closing date, the fair value of the Company’s investment in AvenCell was $ 62.9 million which represents the fair value of the preferred stock received in exchange for the exclusive license to the Company’s CRISPR/Cas9 allogeneic platform (See Note 9). In determining the fair value of the Company’s investment, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants ( 76 %), the probability of AvenCell achieving certain milestones to obtain subsequent financings ( 75 %) and the discount for lack of marketability ( 11 %). The Company recorded the initial investment in AvenCell of $ 62.9 million in “ Equity method investments ” on its consolidated balance sheet. Due to the timing and availability of AvenCell's financial information, the Company will record its share of losses from AvenCell on a quarterly basis on a one-quarter lag from July 30, 2021. Therefore, the Company recorded its share of two months of AvenCell ’s losses generated in the third quarter of 2021 in the Company's operating results and other comprehensive loss in the fourth quarter of 2021, resulting in a reduction of the Company's investment by $ 1.8 million. The Company will record its share of three months of AvenCell 's losses generated in the fourth quarter of 2021 in the Company's operating results in the first quarter of 2022. The Company is not aware of any material events or transactions during this period. The elimination of the intra-entity profit component of $ 2.9 million (See Note 9) resulted in a further reduction in the balance of the investment in AvenCell , bringing the carrying value of the investment to $ 58.1 million as of December 31, 2021. At December 31, 2021, the maximum exposure to loss is limited to the Company’s equity investment in the joint venture. SparingVision SAS In connection with the SparingVision LCA (See Note 9), the Company received 83,316 shares of Series A2 Preferred Stock (“Series A2”). Attached to each share of Series A2, the Company received three warrants for the right to purchase additional Series A2 shares at designated prices that are subject to certain vesting conditions (collectively referred to as the “SparingVision investments”). The Company accounts for the SparingVision investments using the measurement alternative as SparingVision is a private company and there is no readily observable transaction price. In determining the fair value of the SparingVision investments, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants ( 90 %), and the rate of return ( 65 %). The Company recorded the initial investment in SparingVision of $ 14.8 million in “Investments and other assets” on its consolidated balance sheet. There was no change in the observable price of the SparingVision investments as of December 31, 2021. Kyverna Therapeutics, Inc. In connection with the Kyverna LCA (See Note 9), the Company received 3,739,515 shares of Series B Preferred Stock with a fair value of $ 7.0 million. The Company separately made an additional investment in Kyverna, purchasing 1,602,649 shares of Series B Preferred Stock in exchange for $ 3.0 million in cash (collectively referred to as the “Kyverna investments”). The Company accounts for the Kyverna investments using the measurement alternative as Kyverna is a private company and there is no readily observable transaction price. The Company recorded the initial investment in Kyverna of $ 10.0 million in “Investments and other assets” on its consolidated balance sheet. There was no change in the observable price of the Kyverna investment as of December 31, 2021.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	11. Leases In October 2014, the Company entered into an agreement to lease office and laboratory space at 130 Brookline Street (the “130 Brookline Lease”) in Cambridge, Massachusetts under an operating lease agreement with a term through January 2020 , with an option to extend the term of the lease for an additional five-year period. In April 2019, the lease was amended to extend the term for the additional five-year period, through January 2025 . Upon the execution of the original lease, the Company provided a $ 0.3 million security deposit which is recorded in “Investments and other assets” on the Company's consolidated balance sheets. In March 2020, the Company entered into a second amendment to the 130 Brookline Lease (the “130 Brookline Lease Second Amendment”). The 130 Brookline Lease Second Amendment extends the term of the 130 Brookline Lease by approximately six years through January 31, 2031 . This extended term is included as part of the lease liability and right-of-use asset at December 31, 2021. The 130 Brookline Lease Second Amendment also provides an option to extend the lease for two consecutive five-year terms. The option for these further extensions is not included as part of the lease liability and right-of-use asset at December 31, 2021, as it is not reasonably certain that it will be exercised. In the first quarter of 2020, the Company increased the right-of-use asset and liability related to this lease by approximately $ 7.3 million related to the 130 Brookline Lease Second Amendment. In March 2019, the Company entered into a separate agreement to sublease additional office and laboratory space at 130 Brookline Street in Cambridge, Massachusetts under an operating sublease agreement with a term through April 2021 , with two options to extend the agreement by one year each, for a total option period of up to two years . Upon commencement of the lease in April 2019, the Company recognized a right-of-use asset and lease liability of approximately $ 1.3 million. In September 2020, the Company amended the lease to extend the term until October 2021. An adjustment of $ 0.4 million to the right-of-use asset and lease liability was recorded upon the execution of the amendment. This sublease was terminated in September 2021. In January 2016, the Company entered into a ten-year agreement to lease office and laboratory space at 40 Erie Street (the “40 Erie Lease”) in Cambridge, Massachusetts under an operating lease agreement, with an option to terminate the lease at the end of the sixth year and an option to extend the term of the lease for an additional three years . Upon the execution of this lease, the Company provided a $ 2.2 million security deposit, which has been recorded in “Investments and other assets” on the consolidated balance sheets. In November 2020, the Company entered into a second amendment to the 40 Erie Lease (the “40 Erie Lease Second Amendment”) which provides the Company with a right of first offer with respect to any space that becomes available at the 40 Erie Street building, and in consideration for this right the Company agreed to nullify the option to terminate the lease at the end of the sixth year that was included in the 40 Erie Lease. In the fourth quarter of 2020, the Company increased the right-of-use asset and liability related to this lease by approximately $ 18.5 million related to the 40 Erie Lease Second Amendment. In March 2020, the Company entered into an agreement to lease approximately 39,000 square feet of office and laboratory spa ce at 281 Albany Street in Cambridge, Massachusetts under an operating lease agreement (the “281 Albany Lease”). The initial term of the 281 Albany Lease is ten years following the rent commencement date which was determined to be March 2021 in accordance with ASC 842, Leases (Topic 842) ( “ ASC 842 ” ), as that was when the facility was substantially complete and available for use. T he Company recognized a right-of-use asset and a lease liability of approximately $ 40.4 million and $ 34.8 million, respectively, in the first quarter of 2021 related to the 281 Albany Lease. In determining the lease liability, the Company used an incremental borrowing rate of 5.52 % based on a number of factors including the Company’s credit rating and the lease term. Included in the recognized right-of-use asset at the inception of the lease was approximately $ 5.6 million in lease payments that were prepaid under the terms of the lease. The Company modified the right-of-use asset in the second quarter of 2021 based on changes to the configuration of this space, resulting in an additional $ 1.4 million being added to the right-of-use asset. The base rent under the 281 Albany Lease is $ 99.00 per square foot per year during the first year of the term, which is subject to scheduled annual increases up to $ 128.87 per square foot per year during the last year of the initial term, plus certain operating expenses and taxes. In addition, the landlord contributed an aggregate of $ 4.4 million toward the cost of construction and tenant improvements for the premises. In a ccordance with the 281 Albany Lease, the Company is required to maintain a letter of credit in the amount of $ 1.9 million that is restricted for the term of the lease. These restricted cash equivalents are reported in “Investments and other assets” in the Company’s consolidated balance sheet. The Company has the option to extend the 281 Albany Lease for two successive five-year terms ; this option is not included as part of the lease liability and right-of-use asset at December 31, 2021, as it is not reasonably certain that it will be exercised . In July 2021, the Company entered into an agreement to lease 13,662 square feet of office space at 17 Tudor Street in Cambridge, Massachusetts under an operating lease agreement (the “17 Tudor Lease”). The Company’s obligation to pay rent began on November 1, 2021. The initial term of the 17 Tudor Lease is five years and the Company has an option to extend the 17 Tudor Lease for one three-year term. The option is not included as part of the lease liability and right-of-use asset at December 31, 2021, as it is not reasonably certain that it will be exercised. The base rent under the 17 Tudor Lease is $ 74.00 per square foot during the first year of the term, which is subject to scheduled annual increases throughout the term, resulting in a base rent of $ 83.29 per square foot during the last year of the initial term, plus certain operating expenses and taxes. In September 2021 the Company determined, in accordance with ASC 842, that the commencement date of the lease had been met as the Company had gained access to the facility in order to begin work on lessee-owned tenant improvements and, accordingly, the Company recognized a right-of-use asset and a lease liability of approximately $ 4.9 million in the third quarter of 2021 related to the 17 Tudor Lease. In determining the lease liability, the Company used an incremental borrowing rate of 4.15 % based on a number of factors including the Company’s credit rating and the lease term. In accordance with the 17 Tudor Lease, the Company is required to maintain a letter of credit in the amount of $ 0.2 million that is restricted for the term of the lease. These restricted cash equivalents are reported in “Investments and other assets” in the Company’s consolidated balance sheet. In July 2021, the Company entered into an agreement to extend an existing lease for a clean room located in Waltham, Massachusetts under an operating lease agreement (the “Waltham Lease”) for an additional two years. The Company determined, in accordance with ASC 842, that the extension should be accounted for as a lease modification and, accordingly, recorded an adjustment to the right-of-use asset and lease liability of approximately $ 2.5 million in the third quarter of 2021 related to the Waltham Lease. Throughout the term of its leases, the Company is responsible for paying certain costs and expenses, in addition to the rent, as specified in the lease, including a proportionate share of applicable taxes, operating expenses and utilities. The variable portion of these costs are expensed as incurred and are disclosed as variable lease cost. The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating leases for the years ended December 31, 2021 and 2020: Year Ended December 31, 2021 2020 (In thousands) Lease cost Operating lease cost $ 12,871 $ 8,447 Short-term lease cost 31 56 Variable lease cost 3,339 2,918 Total lease cost $ 16,241 $ 11,421 Year Ended December 31, 2021 2020 (In thousands) Other information Operating cash flows used for operating leases $ 12,641 $ 7,495 Operating lease liabilities arising from obtaining right-of-use 49,378 26,432 As Of December 31, 2021 2020 Lease term and discount rate Weighted average remaining lease term 7.2 years 6.7 years Weighted average discount rate 5.50 % 5.80 % The table below reconciles the undiscounted cash flows for each of the next five years and total of the remaining years to the operating lease liabilities recorded in the consolidated balance sheet as of December 31, 2021: Future Operating Lease Payments Year Ending December 31, (in thousands) 2022 $ 12,929 2023 13,398 2024 12,320 2025 12,838 2026 11,544 Thereafter 28,809 Total lease payments $ 91,838 Less: imputed interest ( 17,815 ) Total operating lease liabilities at December 31, 2021 $ 74,023

Equity-Based Compensation

Equity-Based Compensation	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Equity-Based Compensation	12. Equity-Based Compensation Equity-based compensation expense is classified in the consolidated statements of operations and comprehensive loss as follows: Year Ended December 31, 2021 2020 2019 (In thousands) Research and development $ 26,712 $ 10,202 $ 6,986 General and administrative 20,297 9,701 8,105 Total $ 47,009 $ 19,903 $ 15,091 Amended and Restated 2015 Stock Option and Incentive Plan In April 2016, the Company adopted the Amended and Restated 2015 Stock Option and Incentive Plan (the “2015 Plan”). The 2015 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards (“RSAs”), restricted stock units (“RSUs”) and other stock-based awards. Recipients of incentive stock options and non-qualified stock options are eligible to purchase shares of the Company’s common stock at an exercise price equal to the fair value of such stock on the grant date. Stock options granted under the 2015 Plan generally vest 25 % on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years , unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years . As of December 31, 2021, there were 2,241,278 shares available for future issuance under the 2015 Plan. The number of shares reserved for issuance under the 2015 Plan shall be cumulatively increased by four percent of the number of shares of stock issued and outstanding on the immediately preceding December 31 or such lesser number of shares of stock as determined by the board of directors . Restricted Stock Units RSUs are measured at fair value based on the quoted price of the Company’s common stock. The following table summarizes the Company’s RSU activity for the year ended December 31, 2021: Number of Weighted Unvested restricted stock units as of December 31, 2020 193,936 $ 23.98 Granted 451,272 73.81 Vested ( 119,715 ) 20.94 Cancelled ( 72,467 ) 45.14 Unvested restricted stock units as of December 31, 2021 453,026 $ 71.03 In January 2020, the Company granted 181,020 RSUs to certain non-executive employees that included a performance condition in addition to a service condition. These RSUs would vest over a period of three years and were subject to accelerated vesting based on the Company’s programs achieving certain development milestones before December 1, 2022. The fair value of the RSUs at date of grant was $ 15.05 . During the year ended December 31, 2020, the Company achieved one of its development milestones and 58,870 of these RSUs vested. During the year ended December 31, 2021, 26,235 of these RSUs vested based on the satisfaction of a service condition, and 64,290 vested due to the achievement of additional development milestones. At December 31, 2021, none of these RSUs are unvested. The weighted-average grant date fair value of RSUs granted for the years ended December 31, 2021, 2020 and 2019 was $ 73.81 , $ 21.70 and $ 0 . The total fair value of RSUs vested (measured on the date of vesting) for the years ended December 31, 2021 and 2020 was $ 14.1 million and $ 2.8 million, respectively. During the year ended December 31, 2019, RSAs that were granted prior to the Company's IPO vested with a total fair value (measured on the date of vesting) of $ 0.6 million. As of December 31, 2021, there was $ 27.1 million of unrecognized equity-based compensation expense related to RSUs that are expected to vest. These costs are expected to be recognized over a weighted average remaining vesting period of 2.8 years. Stock Options The weighted average grant date fair value of options, estimated as of the grant date using the Black-Scholes option pricing model, was $ 54.09 per option for options granted during the year ended December 31, 2021, $ 9.07 per option for options granted during the year ended December 31, 2020, and $ 9.21 per option for options granted during the year ended December 31, 2019. The total intrinsic value (the amount by which the fair market value exceeded the exercise price) of stock options exercised during the years ended December 31, 2021, 2020 and 2019 was $ 262.0 million, $ 20.3 million, and $ 2.3 million, respectively. Weighted average assumptions used to apply this pricing model were as follows: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 1.0 % 0.8 % 2.1 % Expected life of options 6.0 years 6.0 years 6.0 years Expected volatility of underlying stock 72.9 % 67.8 % 68.1 % Expected dividend yield 0.0 % 0.0 % 0.0 % Risk-free Interest Rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant with maturities approximately equal to the option’s expected term. Expected Dividend Yield. The expected dividend yield assumption is based on the fact that the Company has never paid cash dividends and has no present intention to pay cash dividends. Expected Volatility. The expected volatility was derived from a blend of the Company’s historical volatility and an average of the historical stock volatilities of several peer companies within the Company’s industry, both over a period equivalent to the expected term of the stock option grants. Expected Term. The expected term represents the period that stock option awards are expected to be outstanding. For option grants that are considered to be “plain vanilla,” the Company determines the expected term using the simplified method. The simplified method deems the term to be the average of the time-to-vesting and the contractual life of the options. The Company uses the simplified method because it does not have sufficient historical option exercise data to provide a reasonable basis upon which to estimate the expected term. The Company uses the market closing price of its common stock as reported on the Nasdaq Global Select Market to determine the fair value of the shares of common stock underlying stock options. The following is a summary of stock option activity for the year ended December 31, 2021: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding at December 31, 2020 6,977,440 $ 15.43 Granted 2,729,302 84.16 Exercised ( 2,700,886 ) 15.22 Forfeited ( 700,700 ) 30.74 Outstanding at December 31, 2021 6,305,156 $ 43.57 7.38 $ 492,968 Exercisable at December 31, 2021 2,227,760 $ 16.37 5.43 $ 226,941 As of December 31, 2021, there was $ 130.3 million of unrecognized compensation cost related to stock options that have not yet vested. These costs are expected to be recognized over a weighted average remaining vesting period of 3.1 years. 2016 Employee Stock Purchase Plan In May 2016, the Company adopted the 2016 Employee Stock Purchase Plan (the “2016 Plan”). The 2016 Plan allows eligible employees to purchase shares of the Company’s common stock on the last day of each predetermined six-month offering period at 85 % of the lower of the fair market value per share at the beginning or end of the applicable offering period . The 2016 Plan provides for six-month offering periods beginning in January and July of each year. As of December 31, 2021, there were 1,297,202 shares available for future issuance under the 2016 Plan. The number of shares reserved for issuance under the 2016 Plan shall be cumulatively increased by the lesser of a) one percent of the number of shares of common stock issued and outstanding on the immediately preceding December 31, b) 500,000 shares of common stock, or c) such lesser number of shares of common stock as determined by the board of directors. During the years ended December 31, 2021, 2020, and 2019, the Company issued 30,897 , 101,911 , and 90,581 shares of common stock under the 2016 Plan, respectively. The weighted-average purchase prices of shares issued under the 2016 Plan were $ 65.51 , $ 15.28 , and $ 12.05 per share for the years ended December 31, 2021, 2020, and 2019, respectively. The fair value of the awards issued under the 2016 Plan to employees was estimated at the beginning of the offering period using a Black-Scholes option-pricing model with the following assumptions: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.05 %- 0.09 % 0.17 %- 1.6 % 2.1 %- 2.5 % Expected term (in years) 0.5 years 0.5 years 0.5 years Expected volatility of underlying stock 77.5 %- 109.2 % 53.4 %- 98.3 % 62.9 %- 76.5 % Expected dividend yield 0.0 % 0.0 % 0.0 %

Loss Per Share

Loss Per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Loss Per Share	13. Loss Per Share Basic and diluted loss per share was calculated as follows: Year Ended December 31, 2021 2020 2019 (In thousands) Net loss $ ( 267,892 ) $ ( 134,231 ) $ ( 99,533 ) Weighted average shares outstanding, basic 70,894 55,987 47,247 Net loss per share, basic and diluted $ ( 3.78 ) $ ( 2.40 ) $ ( 2.11 ) The following common stock equivalents were excluded from the calculation of diluted loss per share in 2021, 2020 and 2019 because their inclusion would have been anti-dilutive: Year Ended December 31, 2021 2020 2019 (In thousands) Unvested restricted stock 453 194 72 Stock options 6,305 6,977 5,366 6,758 7,171 5,438

Stockholders_ Equity

Stockholders’ Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders’ Equity	14. Stockholders’ Equity Follow-on Offerings On June 1, 2020, the Company entered into an underwriting agreement related to a public offering of 6,301,370 shares of its common stock, par value $ 0.0001 per share, including the exercise in full by the underwriters of their option to purchase an additional 821,917 shares, at the public offering price of $ 18.25 per share. The offering closed on June 5, 2020 and the Company received net proceeds of $ 107.7 million, after deducting the underwriting discount, commissions and offering expenses. On December 1, 2020, the Company entered into an underwriting agreement related to a public offering of 5,513,699 shares of its common stock, par value $ 0.0001 per share, including the exercise in full by the underwriters of their option to purchase an additional 719,178 shares, at the public offering price of $ 36.50 per share. The offering closed on December 4, 2020 and the Company received net proceeds of $ 188.9 million, after deducting the underwriting discount, commissions and offering expenses. On June 29, 2021, the Company entered into an underwriting agreement related to a public offering of 4,758,620 shares of its common stock , par value $ 0.0001 per share, including the exercise in full by the underwriters of their option to purchase an additional 620,689 shares at a public offering price of $ 145.00 per share. The offering closed on July 2, 2021 and the Company received net proceeds of $ 648.3 million, after deducting the underwriting discount, commissions and offering expenses. At-the-Market Offering Programs In October 2018, the Company entered into an Open Market Sale Agreement (the “2018 Sale Agreement”) with Jefferies LLC (“Jefferies”), under which Jefferies was able to offer and sell, from time to time in “at-the-market” offerings, shares of its common stock having aggregate gross proceeds of up to $ 100.0 million. The Company paid to Jefferies cash commissions of 3.0 % of the gross proceeds of sales of common stock under the 2018 Sale Agreement. The Company issued 5,890,648 shares of its common stock at an average price of $ 16.98 per share in accordance with the 2018 Sale Agreement for aggregate net proceeds of $ 96.4 million, after payment of cash commissions to Jefferies and approximately $ 0.6 million related to legal, accounting and other fees in connection with the sales. All shares related to the 2018 Sale Agreement had been sold as of December 31, 2019. In August 2019, the Company entered into an Open Market Sale Agreement (the “2019 Sale Agreement”) with Jefferies, under which Jefferies was able to offer and sell, from time to time in “at-the-market” offerings, common stock having aggregate gross proceeds of up to $ 150.0 million. The Company agreed to pay Jefferies cash commissions of 3.0 % of the gross proceeds of sales of common stock under the 2019 Sale Agreement. During the year ended December 31, 2019, the Company issued 287,231 shares of its common stock, in a series of sales, at an average price of $ 16.48 per share, in accordance with the 2019 Sale Agreement for aggregate net proceeds of $ 4.4 million, after payment of cash commissions to Jefferies and approximately $ 0.2 million related to legal, accounting and other fees in connection with the sales. During the year ended December 31, 2020, the Company issued 2,270,161 shares of its common stock in a series of sales at an average price of $ 22.53 per share in accordance with the 2019 Sale Agreement, for aggregate net proceeds of $ 49.5 million after payment of cash commissions to Jefferies and approximately $ 0.2 million related to legal, accounting and other fees in connection with the sales. During the year ended December 31, 2021, the Company issued 641,709 shares of its common stock in a series of sales at an average price of $ 72.79 per share in accordance with the 2019 Sale Agreement, for aggregate net proceeds of $ 45.3 million after payment of cash commissions to Jefferies and approximately $ 0.1 million related to legal, accounting and other fees in connection with the sales. As of December 31, 2021, $ 47.4 million in shares of common stock remain eligible for sale under the 2019 Sale Agreement. Shares Issued in Private Placement to Regeneron As described in Note 9 above, in May 2020 the Company entered into an amendment to its collaboration agreement with Regeneron that was entered into in April 2016. Simultaneously, the Company and Regeneron entered into the 2020 Stock Purchase Agreement , under which the Company sold to Regeneron 925,218 shares of its common stock, par value $ 0.0001 per share, for aggregate cash consideration of $ 30.0 million, or $ 32.42 per share, representing a 100 % premium over the volume-weighted average trading price of the Company’s common stock during the 30-day period prior to the closing. Under the 2020 Stock Purchase Agreement, Regeneron will not dispose of any shares of common stock it beneficially owns in the Company until the termination of the Technology Collaboration Term (see Note 9). After applying equity accounting guidance to measure the issuance of the shares, $ 12.6 million was recorded as fair value in the consolidated statement of stockholders’ equity for the shares.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	15. Related Party Transactions In the ordinary course of business, the Company may purchase materials or supplies from entities that are associated with a party that meets the criteria of a related party of the Company. These transactions are reviewed quarterly and to date have not been material to the Company’s consolidated financial statements. The Company and AvenCell are parties to the AvenCell LCA and AvenCell Co/Co, as described in Note 9. The Company’s relationship with AvenCell is considered to be as a related party due to the Company’s 33.33 % investment in AvenCell being accounted for under the equity method. T he Company recognized $ 5.9 million and $ 0.2 million in revenue u nder the AvenCell LCA and AvenCell Co/Co, respectively, for the year ended December 31, 2021. As of December 31, 2021 the Company had deferred revenue of $ 54.1 million, comprised of $ 34.2 million in current deferred revenue and $ 19.9 million in non-current deferred revenue, related to the AvenCell LCA. The Company and Kyverna are parties to the Kyverna LCA and are considered to be related parties because they have a common board member (see Note 9). The Company owns preferred stock of Kyverna, the value of which is included in “Investments and other assets” in the consolidated balance sheet. The value of this investment was $ 10.0 million as of December 31, 2021. There was no revenue recognized in the year ended December 31, 2021 related to the Kyverna LCA. As of December 31, 2021, the Company had deferred revenue of $7.0 million related to the Kyverna LCA.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
401(k) Plan	16. 401(k) Plan In 2015, the Company established the Intellia Therapeutics, Inc. 401(k) Plan (the “401(k) Plan”) for its employees, which is designed to be qualified under Section 401(k) of the Internal Revenue Code. Eligible employees are permitted to contribute to the 401(k) Plan within statutory and 401(k) Plan limits. The Company makes matching contributions of 50 % of the first 6 % of employee contributions. The Company made matching contributions of $ 1.6 million, $ 1.1 million and $ 0.8 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	17. Subsequent Events In January 2022, the Company entered into a Lease Agreement (the “Lease”) with the Massachusetts Institute of Technology (the “Landlord”) for office and laboratory space located at 730 Main Street, Cambridge, Massachusetts (the “Premises”). Under the terms of the Lease, the Company will lease approximately 38,000 square feet at the Premises, which will supplement the Company’s current leased premises in Cambridge, Massachusetts. The Lease, including the obligation to pay rent, is expected to commence on October 22, 2022 (the “Commencement Date”). The initial term of the Lease is ten years following the Commencement Date. The base rent under the Lease is $ 130.00 per square foot per year during the first year of the term, which is subject to scheduled annual increases up to $ 169.62 per square foot per year during the last year of the initial term, plus certain operating expenses and taxes. The Company has the option to extend the Lease for one five-year term . On February 2, 2022, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with RW Acquisition Corp., a Delaware corporation and a wholly-owned direct subsidiary of the Company (“Merger Sub”), Rewrite Therapeutics, Inc., a Delaware corporation (“Rewrite”) and Shareholder Representative Services LLC, a Colorado limited liability company, solely in its capacity as the representative of the Rewrite Holders (as defined below). On the effective date of the Merger Agreement, Merger Sub merged with and into Rewrite, with Rewrite surviving as a wholly-owned direct subsidiary of the Company. Pursuant to the Merger Agreement, and subject to the terms and conditions thereof, the Company paid Rewrite’s former stockholders and optionholders (the “Rewrite Holders”) upfront consideration in an aggregate amount of approximately $ 45.0 million payable in cash, excluding customary purchase price adjustments. In addition, the Rewrite Holders will be eligible to receive up to an additional $ 155.0 million in milestone payments upon the achievement of certain pre-specified research and regulatory approval milestones, payable through a mixture of $ 130.0 million in cash and $ 25.0 million in shares of common stock, par value $ 0.0001 per share (“Common Stock”). The shares of Common Stock will be valued using the volume-weighted average price of Common Stock of the Company over the ten consecutive trading day period ending on and including the trading day that is two trading days immediately prior to the issuance of the consideration issued in connection with the applicable milestone. On February 12, 2022 the Company entered into a license, collaboration and option agreement with ONK Therapeutics, Ltd. (“ONK”), an innovative company dedicated to developing optimally engineered natural killer (“NK”) cell therapies to cure patients with cancer. The agreement grants ONK a non-exclusive license to the Company's proprietary ex vivo CRISPR/Cas9-based genome editing platform and its LNP-based delivery technologies for development of up to five allogeneic NK cell therapies, which license is exclusive with respect to certain gRNAs. ONK will be responsible for preclinical and clinical development for the engineered NK cell therapies enabled by the agreement. The Company will be eligible to receive up to $ 184 million per product in development and commercial milestone payments, as well as up to mid-single digit royalties on potential future sales. In addition, the agreement grants the Company options to co-develop and co-commercialize up to two products developed through the collaboration worldwide with rights to lead commercialization in the U.S. In February 2022, the Company entered into a Lease Agreement (the “Winter Street Lease”) with ARE-Winter Street Property, LLC (the “Landlord”) for manufacturing space located at 840 Winter Street, Waltham, Massachusetts (the “Premises”). Under the terms of the Winter Street Lease, the Company will lease approximately 140,000 square feet at the Premises, which will provide the Company with the ability to manufacture its own products in a GMP compliant facility as well as to supplement the Company’s current leased premises in Cambridge, Massachusetts. The Winter Street Lease, including the obligation to pay rent, is expected to commence on February 1, 2024 (the “Commencement Date”). The initial term of the Winter Street Lease is twelve years following the Commencement Date. The base rent under the Winter Street Lease is $ 73.50 per square foot per year during the first year of the term, which is subject to scheduled 3% annual increases, plus certain operating expenses and taxes. The Company has the option to extend the Winter Street Lease for two five-year terms.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of Intellia Therapeutics, Inc. and its wholly owned, controlled subsidiary, Intellia Securities Corp. All intercompany balances and transactions have been eliminated in consolidation. Comprehensive loss is comprised of net loss and gain/loss on marketable securities and equity method investments.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) requires management to make estimates, judgments and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates in these consolidated financial statements have been made in connection with the calculation of revenues, research and development expenses, valuation of equity and fair value method investments, and equity-based compensation expense. The Company bases its estimates on historical experience and various other assumptions that management believes to be reasonable under the circumstances at the time such estimates are made. Actual results could differ from those estimates. The Company periodically reviews its estimates in light of changes in circumstances, facts and experience. The extent of the impact of the coronavirus disease 19 (“COVID-19”) pandemic on the Company’s operational and financial performance will depend on certain developments, including the length and severity of this pandemic, as well as its effect on the Company's employees, collaborators and vendors, all of which are uncertain and cannot be predicted. The Company cannot reasonably estimate the extent to which the disruption may materially impact its consolidated results of operations or financial position. The effects of material revisions in estimates are reflected in the consolidated financial statements prospectively from the date of the change in estimate.
Fair Value Measurements	Fair Value Measurements The Company’s financial instruments include cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses. Certain of the Company’s financial assets, including cash equivalents and marketable securities, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third-party pricing services or other observable market data. The pricing services utilize industry standard valuation models and observable market inputs to determine value. Refer to Note 4 for further information regarding the Company’s fair value measurements. Other financial instruments, including accounts receivable, accounts payable and accrued expenses, are carried at cost, which approximate fair value due to the short duration and term to maturity.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. As of December 31, 2021 and 2020, cash equivalents consisted of interest-bearing money market accounts.
Restricted Cash Equivalents	Restricted Cash Equivalents The Company has restricted cash equivalents made up of money market funds held in collateral accounts that are restricted to secure letters of credit in accordance with the leases for 281 Albany Street and 17 Tudor Street, which the Company entered into in March of 2020 and July of 2021, respectively (see Note 11). The letters of credit, in the amount of $ 1.9 million and $ 0.2 million, respectively, are required to be maintained throughout the term of the leases. These restricted cash equivalents are long-term in nature and are included in “Investments and other assets” in the Company’s consolidated balance sheets. The Company has also received funds from certain grants that were restricted as to their use and were therefore classified as restricted cash equivalents. These funds amounted to approximately $ 2.7 million as of December 31, 2020 and were used in full prior to December 31, 2021. Accordingly, these funds were included in “Prepaid expenses and other current assets” in the Company’s consolidated balance sheet for the period ended December 31, 2020.
Marketable Securities	Marketable Securities The Company’s marketable securities are accounted for as available-for-sale and recorded at fair value with the related unrealized gains and losses included in accumulated other comprehensive (loss)/income, a component of stockholders’ equity. The Company reviews its investment portfolio to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. Refer to Note 3 for further information regarding the Company’s marketable securities.
Non-Marketable Equity Securities	Non-Marketable Equity Securities The Company also invests in equity securities of companies whose securities are not publicly traded and where fair value is not readily available. These investments are accounted for using the measurement alternative at cost minus impairment adjusted for changes in observable prices. The Company monitors these investments to evaluate whether any increase or decline in their value has occurred, based on the implied value of recent company financings and general market conditions, or if the investment has a readily determinable fair value. These investments are included in “Investments and other assets” in the Company’s consolidated balance sheets. Refer to Note 10 for further information regarding the Company’s investments in non-marketable equity securities.
Concentrations of Credit Risk	Concentrations of Credit Risk The Company’s cash, cash equivalents and marketable securities may potentially be subject to concentrations of credit risk. The Company generally maintains balances in various accounts in excess of federally insured limits with financial institutions that management believes to be of high credit quality. Accounts receivable represents amounts due from collaboration partners and joint ventures. The Company monitors economic conditions to identify facts or circumstances that may indicate that any of its accounts receivable are at risk of collection. As of December 31, 2021, the Company’s accounts receivable were related to its collaborations with Regeneron Pharmaceuticals, Inc. (“Regeneron”) and AvenCell Therapeutics, Inc. (“AvenCell”), a new universal chimeric antigen receptor T (“CAR-T”) cell therapy joint venture and privately held company established by the Company, Cellex Cell Professionals GmbH (“Cellex”) and funds managed by Blackstone Life Sciences Advisors L.L.C. (“BXLS”) . As of December 31, 2020, Regeneron accounted for all of the Company’s accounts receivable.
Property and Equipment	Property and Equipment The Company records property and equipment at cost and recognizes depreciation and amortization using the straight-line method over the following estimated useful lives of the respective assets: Asset Category Useful Life Laboratory equipment 5 years Office furniture and equipment 5 years Computer software 3 years Computer equipment 3 years Leasehold improvements 5 years or term of respective lease, if shorter Expenditures for repairs and maintenance of assets are expensed as incurred. Upon retirement or sale, the cost of assets disposed and the corresponding accumulated depreciation are removed from the related accounts and any resulting gain or loss is reflected in the results of operations.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company tests long-lived assets to be held and used, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of assets or asset groups may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. Evaluation of recoverability of the asset or asset group is based on an estimate of undiscounted future cash flows resulting from the use of the asset or asset group and its eventual disposition. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the asset or asset group, the assets are written down to their estimated fair values. The impairment loss would be based on the excess of the carrying value of the impaired asset over its fair value, determined based on discounted cash flows. To date, the Company has not recorded any material impairment losses on long-lived assets.
Income Taxes	Income Taxes The Company accounts for income taxes using the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences attributable to differences between carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax reporting purposes and for operating loss and tax credit carryforwards. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company’s deferred tax assets and liabilities are measured using enacted tax rates expected to apply in the years in which these temporary differences are expected to be recovered or settled. A valuation allowance is recorded to reduce deferred tax assets if it is determined that it is more likely than not that all or a portion of the deferred tax asset will not be realized. The Company considers many factors when assessing the likelihood of future realization of deferred tax assets, including recent earnings results, expectations of future taxable income, carryforward periods available and other relevant factors. The Company records changes in the required valuation allowance in the period that the determination is made. The Company assesses its income tax positions and records tax benefits for all years subject to examination based upon management’s evaluation of the facts, circumstances and information available as of the reporting date. For those tax positions where it is more likely than not that a tax benefit will be sustained, the Company records the largest amount of tax benefit with a greater than 50 % likelihood of being realized upon ultimate settlement with a taxing authority having full knowledge of all relevant information. For those income tax positions where it is not more likely than not that a tax benefit will be sustained, the Company does not recognize a tax benefit in the financial statements. The Company records interest and penalties related to uncertain tax positions, if applicable, as a component of income tax expense.
Revenue Recognition	Revenue Recognition The Company recognizes revenue in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) and its related amendments (collectively known as Accounting Standard Codification (“ASC”) 606 (“ASC 606”). At inception, the Company determines whether contracts are within the scope of ASC 606 or other topics. For contracts that are determined to be within the scope of ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these goods and services. To achieve this core principle, the Company applies the following five steps: (i) identify the contract with the customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as the Company satisfies a performance obligation. The Company only applies the five-step model to contracts when the Company determines that collection of substantially all consideration for goods and services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct and are distinct in the context of the contract. To the extent a contract includes multiple promised goods and services, the Company applies judgment to determine whether promised goods and services are both capable of being distinct and distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation. The transaction price is determined based on the consideration to which the Company will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method, depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. Determining the transaction price requires significant judgment, which is discussed in further detail for each of the Company’s collaboration agreements in Note 9. In addition, none of the Company’s contracts as of December 31, 2021 contained a significant financing component. If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation. The consideration to be received is allocated among the separate performance obligations based on relative standalone selling prices. The Company typically determines standalone selling prices using an adjusted market assessment approach model. The Company satisfies performance obligations either over time or at a point in time. Revenue is recognized over time if either (i) the customer simultaneously receives and consumes the benefits provided by the entity’s performance, (ii) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced, or (iii) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. If the entity does not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring the control of a promised good or service to a customer. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. As of December 31, 2021, the Company’s only revenue recognized is related to collaboration agreements with third parties which are either within the scope of ASC 606, under which the Company licenses certain rights to its product candidates to third parties, or within the scope of ASC 808, Collaborative Arrangements (“ASC 808”) if it involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards with respect to the arrangement. For the collaboration arrangements under the scope of ASC 606, as discussed in further detail in Note 9, the terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront fees; development, regulatory, and commercial milestone payments; research and development funding payments; and royalties on the net sales of licensed products. Additionally, the terms of certain arrangements may include an equity interest in the other company. Each of these payments results in collaboration revenues, except for revenues from royalties on the net sales of licensed products, which are classified as royalty revenues. For arrangements within the scope of ASC 808, the terms of these arrangements typically include payments received or made under the cost sharing provisions which are recognized as a component of revenues in the consolidated statements of operations and comprehensive loss. Licenses of intellectual property: If the license to the Company’s IP is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from consideration allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the licenses. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. Milestone payments: At the inception of each arrangement that includes development milestone payments, the Company evaluates the probability of reaching the milestones and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur in the future, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received and therefore revenue recognized is constrained as management is unable to assert that a reversal of revenue would not be probable. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenues and earnings in the period of adjustment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on levels of sales, if the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaboration agreements. The Company receives payments from its customers based on billing schedules or upon the achievement of milestones established in each contract. The Company’s contract liabilities consist of deferred revenue. Upfront payments and fees are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company satisfies its obligations under these arrangements. The Company also considers the nature and contractual terms of an arrangement and assesses whether the arrangement involves a joint operating activity pursuant to which the Company is an active participant and is exposed to significant risks and rewards with respect to the arrangement. If the Company is an active participant and is exposed to the significant risks and rewards with respect to the arrangement, the Company accounts for the arrangement under ASC 808 . Based on this consideration, the Company accounts for its co-development and co-promotion (“Co/Co”) Agreements with Regeneron and AvenCell under ASC 808. Because ASC 808 does not provide recognition and measurement guidance for collaborative arrangements, the Company has analogized to ASC 606. Refer to Note 9 for additional information regarding the Company’s collaboration agreements.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Research and development expenses consist of expenses incurred in performing research and development activities, such as salaries, equity-based compensation and benefits of employees, allocated facility-related expenses, overhead expenses, license, sublicense and milestone fees, contract research, clinical trial costs, development and manufacturing services, and other related costs. The Company records payments made for research and development services prior to the services being rendered as prepaid expenses on the consolidated balance sheet and expenses them as the services are provided. Contracts for multi-year research and development services are recorded on a straight-line basis over each annual contractual period based on the total contractual fee when the services rendered are expected to be substantially equivalent over the term of the arrangement. The cost of obtaining licenses for certain technology or IP is recorded to research and development expense when incurred if the licensed technology or IP has not yet reached technological feasibility and has no alternative future use.
Equity-Based Compensation	Equity-Based Compensation The Company measures employee equity-based compensation based on the grant date fair value of the equity awards using the Black-Scholes option pricing model. Equity-based compensation expense is recognized on a straight-line basis over the requisite service period of the awards and is adjusted for pre-vesting forfeitures in the period in which the forfeitures occur. For equity awards that have a performance condition, the Company recognizes stock-based compensation expense using the accelerated attribution method, based on its assessment of the probability that the performance condition will be achieved. The Company classifies equity-based compensation expense in its consolidated statement of operations and comprehensive loss in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified.
(Loss) Earnings per Share	(Loss) Earnings per Share The Company calculates basic (loss) earnings per share by dividing net (loss) income for each respective period by the weighted average number of common shares outstanding for each respective period. The Company computes diluted (loss) earnings per share after giving consideration to the dilutive effect of stock options and unvested restricted stock that are outstanding during the period, except where such securities would be anti-dilutive.
Segment Information	Segment Information The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s one business segment is the development of genome editing-based therapies. All of the Company’s assets are held in the U.S. and all of the Company’s revenue has been generated in the U.S.
Variable Interest Entity	Variable Interest Entity The Company evaluates at the inception of each arrangement, and whenever a reconsideration event occurs, whether an entity in which the Company holds an investment or in which the Company has other variable interests is considered a variable interest entity (“VIE”) in accordance with FASB ASC Topic 810, Consolidation (“ASC 810”). If the entity meets the criteria to qualify as a VIE, the Company assesses whether or not the Company is the primary beneficiary of that VIE based on a number of factors, including (i) which party has the power to direct the activities that most significantly affect the VIE’s economic performance, (ii) the parties’ contractual rights and responsibilities pursuant to any contractual agreements and (iii) which party has the obligation to absorb losses or the right to receive benefits from the VIE. If the Company is deemed the primary beneficiary of a VIE, the Company consolidates such entity and reflects the non-controlling interest of other beneficiaries of that entity. If the Company is not the primary beneficiary, no consolidation is necessary, and the Company accounts for the investment or other variable interest in accordance with applicable U.S. GAAP.
Equity Method of Accounting	Equity Method of Accounting In circumstances where the Company has the ability to exercise significant influence, but not control, over the operating and financial policies of an entity in which the Company has a common stock or in-substance common stock investment, the Company utilizes the equity method of accounting for recording related investment activity. In assessing whether the Company exercises significant influence, the Company considers the nature and magnitude of the investment, the voting and protective rights the Company holds, any participation in the governance of the other entity and other relevant factors such as the presence of a collaborative or other business relationship. Under the equity method of accounting, the Company’s investments are initially recorded at cost on the consolidated balance sheets. Upon recording an equity method investment, the Company evaluates whether there are basis differences between the carrying value and fair value of the Company’s proportionate share of the investee’s underlying net assets. Typically, the Company amortizes basis differences identified on a straight-line basis over the underlying assets’ estimated useful lives when calculating the attributable earnings or losses, excluding the basis differences attributable to in-process research and development (“IPR&D”) that has no alternative future use. If the Company is unable to attribute all of the basis difference to specific assets or liabilities of the investee, the residual excess of the cost of the investment over the proportional fair value of the investee’s assets and liabilities is considered to be Equity Method Goodwill and is recognized within the equity investment balance, which is tracked separately within the Company’s memo accounts. The Company subsequently records in the consolidated statements of operations and comprehensive loss its share of income or loss of the other entity within other income/expense. If the share of losses exceeds the carrying value of the Company’s investment, the Company will suspend recognizing additional losses and will continue to do so unless it commits to providing additional funding; however, if there are intra-entity profits this can cause the investment balance to go negative. The Company evaluates its equity method investments for impairment whenever events or changes in circumstance indicate that the carrying amounts of such investments may be impaired and considers qualitative and quantitative factors including the investee's financial metrics, product and commercial outlook and cash usage. If a decline in the value of an equity method investment is determined to be other than temporary, a loss is recorded in earnings in the current period and the investment is written down to fair value. At December 31, 2021, the Company accounted for its investment in AvenCell under the equity method of accounting and no impairment charges were recognized during the year ended December 31, 2021. Refer to Note 10 for further details.
Recent Accounting Pronouncements – Adopted	Recent Accounting Pronouncements – Adopted In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes . ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The Company adopted ASU 2019-12 on January 1, 2021. The adoption did not have a material effect on the Company’s consolidated financial statements .

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Property and Equipment at Cost and Recognizes Depreciation and Amortization Using the Straight-Line Method Over Estimated Useful Lives	The Company records property and equipment at cost and recognizes depreciation and amortization using the straight-line method over the following estimated useful lives of the respective assets: Asset Category Useful Life Laboratory equipment 5 years Office furniture and equipment 5 years Computer software 3 years Computer equipment 3 years Leasehold improvements 5 years or term of respective lease, if shorter

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-sale Marketable Securities	The following table summarizes the Company’s available-for-sale marketable securities as of December 31, 2021 and 2020 at net book value: December 31, 2021 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government securities $ 301,493 $ - $ ( 1,016 ) $ 300,477 Financial institution debt securities 441,068 - ( 652 ) 440,416 Corporate debt securities 62,500 - ( 151 ) 62,349 Other asset-backed securities 159,707 - ( 306 ) 159,401 Total $ 964,768 $ - $ ( 2,125 ) $ 962,643 December 31, 2020 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government securities $ 245,666 $ 13 $ ( 11 ) $ 245,668 Financial institution debt securities 138,445 6 ( 8 ) 138,443 Corporate debt securities 41,765 3 ( 2 ) 41,766 Other asset-backed securities 11,474 1 ( 1 ) 11,474 Total $ 437,350 $ 23 $ ( 22 ) $ 437,351

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Summary of Financial Assets Recognized at Fair Value on Recurring Basis	As of December 31, 2021 and 2020, the Company’s financial assets recognized at fair value on a recurring basis consisted of the following: Fair Value as of December 31, 2021 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents and restricted cash equivalents $ 124,636 $ 124,636 $ - $ - Marketable securities: U.S. Treasury and other government securities 300,477 280,085 20,392 - Financial institution debt securities 440,416 - 440,416 - Corporate debt securities 62,349 - 62,349 - Other asset-backed securities 159,401 - 159,401 - Total marketable securities 962,643 280,085 682,558 - Total $ 1,087,279 $ 404,721 $ 682,558 $ - Fair Value as of December 31, 2020 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents and restricted cash equivalents $ 163,805 $ 163,805 $ - $ - Marketable securities: U.S. Treasury and other government securities 245,668 241,664 4,004 - Financial institution debt securities 138,443 - 138,443 - Corporate debt securities 41,766 - 41,766 - Other asset-backed securities 11,474 - 11,474 - Total marketable securities 437,351 241,664 195,687 - Total $ 601,156 $ 405,469 $ 195,687 $ -

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment, net consisted of the following: December 31, 2021 2020 (In thousands) Laboratory equipment $ 39,840 $ 30,438 Office furniture and equipment 2,186 1,181 Computer equipment 1,318 1,076 Leasehold improvements 2,188 1,520 Computer software 1,550 1,059 Total property and equipment 47,082 35,274 Less: accumulated depreciation and amortization ( 26,114 ) ( 19,331 ) Property and equipment, net $ 20,968 $ 15,943

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: December 31, 2021 2020 (In thousands) Employee compensation and benefits $ 20,359 $ 10,920 Accrued research and development 16,979 11,008 Accrued legal and professional expenses 3,100 1,876 Accrued other 2,871 1,750 Total accrued expenses $ 43,309 $ 25,554

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of the Federal Statutory Income Tax Rate and the Company's Effective Income Tax Rate	A reconciliation of the federal statutory income tax rate and the Company’s effective income tax rate is as follows: Year Ended December 31, 2021 2020 2019 Federal statutory income tax rate ( 21.0 )% ( 21.0 )% ( 21.0 )% State income taxes ( 16.6 ) ( 7.4 ) ( 8.9 ) Research and development tax credits ( 8.7 ) ( 1.8 ) ( 5.1 ) Stock-based compensation ( 16.8 ) ( 1.3 ) 1.2 162m 0.2 - - Change in valuation allowance 62.9 31.5 33.8 Effective income tax rate — % — % — %
Summary of Company's Net Deferred Tax Assets (Liabilities)	The Company’s net deferred tax assets (liabilities) consisted of the following: December 31, 2021 2020 (in thousands) Deferred tax assets: Intangibles, including acquired in-process $ 1,010 $ 981 Capitalized start-up costs 334 378 Net operating loss carryforwards 216,629 101,807 Research and development credit carryforwards 61,698 23,166 Operating lease liability 20,055 10,713 Deferred revenue 13,922 4,680 Equity-based compensation 7,774 8,574 Accruals and allowances 3,718 2,200 Prepaid rent 1,393 - Equity investment adjustments 359 - Gross deferred tax assets 326,892 152,499 Deferred tax asset valuation allowance ( 304,781 ) ( 140,868 ) Total deferred tax assets 22,111 11,631 Deferred tax liabilities: Fixed assets ( 669 ) ( 970 ) Operating lease right-of-use assets ( 21,442 ) ( 10,661 ) Total deferred tax liabilities ( 22,111 ) ( 11,631 ) Net deferred tax asset (liability) $ - $ -

Collaborations (Tables)

Collaborations (Tables)	12 Months Ended
	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Changes in Accounts Receivable and Contract Liabilities	The following table presents changes in the Company’s accounts receivable and contract liabilities during the years ended December 31, 2021 and 2020 (in thousands): Balance at Additions Deductions Balance at End Year Ended December 31, 2021 Accounts receivable $ 2,130 $ 7,559 $ ( 7,658 ) $ 2,031 Contract liabilities: Deferred revenue $ 73,931 $ 84,659 $ ( 31,355 ) $ 127,235 Balance at Additions Deductions Balance at End Year Ended December 31, 2020 Accounts receivable $ 4,620 $ 103,116 $ ( 105,606 ) $ 2,130 Contract liabilities: Deferred revenue $ 28,810 $ 87,477 $ ( 42,356 ) $ 73,931
Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance	During the years ended December 31, 2021 and 2020, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Revenue recognized in the period from: Year Ended Year Ended Amounts included in the contract liability at the beginning of the period $ 22,544 $ 11,571

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Summary of Lease Costs and Other Information	The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating leases for the years ended December 31, 2021 and 2020: Year Ended December 31, 2021 2020 (In thousands) Lease cost Operating lease cost $ 12,871 $ 8,447 Short-term lease cost 31 56 Variable lease cost 3,339 2,918 Total lease cost $ 16,241 $ 11,421 Year Ended December 31, 2021 2020 (In thousands) Other information Operating cash flows used for operating leases $ 12,641 $ 7,495 Operating lease liabilities arising from obtaining right-of-use 49,378 26,432 As Of December 31, 2021 2020 Lease term and discount rate Weighted average remaining lease term 7.2 years 6.7 years Weighted average discount rate 5.50 % 5.80 %
Schedule of Reconciliation of Undiscounted Cash Flows for Operating Lease Liabilities / Future Minimum Lease Payments	The table below reconciles the undiscounted cash flows for each of the next five years and total of the remaining years to the operating lease liabilities recorded in the consolidated balance sheet as of December 31, 2021: Future Operating Lease Payments Year Ending December 31, (in thousands) 2022 $ 12,929 2023 13,398 2024 12,320 2025 12,838 2026 11,544 Thereafter 28,809 Total lease payments $ 91,838 Less: imputed interest ( 17,815 ) Total operating lease liabilities at December 31, 2021 $ 74,023

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Equity-Based Compensation Expense	Equity-based compensation expense is classified in the consolidated statements of operations and comprehensive loss as follows: Year Ended December 31, 2021 2020 2019 (In thousands) Research and development $ 26,712 $ 10,202 $ 6,986 General and administrative 20,297 9,701 8,105 Total $ 47,009 $ 19,903 $ 15,091
Summary of Restricted Stock Activity	The following table summarizes the Company’s RSU activity for the year ended December 31, 2021: Number of Weighted Unvested restricted stock units as of December 31, 2020 193,936 $ 23.98 Granted 451,272 73.81 Vested ( 119,715 ) 20.94 Cancelled ( 72,467 ) 45.14 Unvested restricted stock units as of December 31, 2021 453,026 $ 71.03
Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted	Weighted average assumptions used to apply this pricing model were as follows: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 1.0 % 0.8 % 2.1 % Expected life of options 6.0 years 6.0 years 6.0 years Expected volatility of underlying stock 72.9 % 67.8 % 68.1 % Expected dividend yield 0.0 % 0.0 % 0.0 %
Summary of Stock Option Activity	The following is a summary of stock option activity for the year ended December 31, 2021: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding at December 31, 2020 6,977,440 $ 15.43 Granted 2,729,302 84.16 Exercised ( 2,700,886 ) 15.22 Forfeited ( 700,700 ) 30.74 Outstanding at December 31, 2021 6,305,156 $ 43.57 7.38 $ 492,968 Exercisable at December 31, 2021 2,227,760 $ 16.37 5.43 $ 226,941
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted	The fair value of the awards issued under the 2016 Plan to employees was estimated at the beginning of the offering period using a Black-Scholes option-pricing model with the following assumptions: Year Ended December 31, 2021 2020 2019 Risk-free interest rate 0.05 %- 0.09 % 0.17 %- 1.6 % 2.1 %- 2.5 % Expected term (in years) 0.5 years 0.5 years 0.5 years Expected volatility of underlying stock 77.5 %- 109.2 % 53.4 %- 98.3 % 62.9 %- 76.5 % Expected dividend yield 0.0 % 0.0 % 0.0 %

Loss Per Share (Tables)

Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	Basic and diluted loss per share was calculated as follows: Year Ended December 31, 2021 2020 2019 (In thousands) Net loss $ ( 267,892 ) $ ( 134,231 ) $ ( 99,533 ) Weighted average shares outstanding, basic 70,894 55,987 47,247 Net loss per share, basic and diluted $ ( 3.78 ) $ ( 2.40 ) $ ( 2.11 )
Potential Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share	The following common stock equivalents were excluded from the calculation of diluted loss per share in 2021, 2020 and 2019 because their inclusion would have been anti-dilutive: Year Ended December 31, 2021 2020 2019 (In thousands) Unvested restricted stock 453 194 72 Stock options 6,305 6,977 5,366 6,758 7,171 5,438

The Company - Additional Inform

The Company - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering	$ 1,817,900
Follow-on public Offerings [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering	648,315	$ 296,607	$ 0
At The Market Offerings
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering	$ 45,255	$ 49,461	$ 72,256

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)Segment	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Summary Of Significant Accounting Policies [Line Items]
Restricted cash equivalents	$ 2,080	$ 4,586	$ 0
Percentage of likelihood of realization required to record tax benefit	50.00%
Number of reportable segment | Segment	1
Albany Lease [Member]
Summary Of Significant Accounting Policies [Line Items]
Term of lease	10 years
Albany Lease [Member] | Other Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash equivalents	$ 1,900
Tudor Lease [Member]
Summary Of Significant Accounting Policies [Line Items]
Term of lease	5 years
Tudor Lease [Member] | Other Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash equivalents	$ 200
Albany and Tudor Lease | Prepaid Expense and Other Current Assets [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash equivalents		$ 2,700

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Property and Equipment at Cost and Recognizes Depreciation and Amortization Using the Straight-Line Method Over Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2021
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years or term of respective lease, if shorter

Marketable Securities - Summary

Marketable Securities - Summary of Available -for-sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Amortized Cost	$ 964,768	$ 437,350
Gross Unrealized Gains		23
Gross Unrealized Losses	(2,125)	(22)
Estimated Fair Value	962,643	437,351
U.S. Treasury and Other Government Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	301,493
Gross Unrealized Losses	(1,016)
Estimated Fair Value	300,477
Financial Institution Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	441,068	138,445
Gross Unrealized Gains		6
Gross Unrealized Losses	(652)	(8)
Estimated Fair Value	440,416	138,443
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	62,500	41,765
Gross Unrealized Gains		3
Gross Unrealized Losses	(151)	(2)
Estimated Fair Value	62,349	41,766
Other Asset Backed Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	159,707	11,474
Gross Unrealized Gains		1
Gross Unrealized Losses	(306)	(1)
Estimated Fair Value	$ 159,401	11,474
U.S. Treasury Securities [Member]
Marketable Securities [Line Items]
Amortized Cost		245,666
Gross Unrealized Gains		13
Gross Unrealized Losses		(11)
Estimated Fair Value		$ 245,668

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Realized gains or losses on marketable securities	$ 0	$ 0	$ 0
Investments that matured beyond five years	$ 0	$ 0
Minimum [Member]
Marketable Securities [Line Items]
Available-for-sales Securities, non-current, maturity period	1 year
Maximum [Member]
Marketable Securities [Line Items]
Available-for-sales Securities, non-current, maturity period	5 years

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Recognized at Fair Value on Recurring Basis (Detail) - Fair Value on Recurring Basis [Member] - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and restricted cash equivalents	$ 124,636	$ 163,805
Marketable securities:
Marketable securities	962,643	437,351
Total	1,087,279	601,156
U.S. Treasury and Other Government Securities [Member]
Marketable securities:
Marketable securities	300,477	245,668
Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	440,416	138,443
Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	62,349	41,766
Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	159,401	11,474
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and restricted cash equivalents	124,636	163,805
Marketable securities:
Marketable securities	280,085	241,664
Total	404,721	405,469
Level 1 [Member] | U.S. Treasury and Other Government Securities [Member]
Marketable securities:
Marketable securities	280,085	241,664
Level 2 [Member]
Marketable securities:
Marketable securities	682,558	195,687
Total	682,558	195,687
Level 2 [Member] | U.S. Treasury and Other Government Securities [Member]
Marketable securities:
Marketable securities	20,392	4,004
Level 2 [Member] | Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	440,416	138,443
Level 2 [Member] | Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	62,349	41,766
Level 2 [Member] | Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	$ 159,401	$ 11,474

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 47,082	$ 35,274
Less: accumulated depreciation and amortization	(26,114)	(19,331)
Property and equipment, net	20,968	15,943
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	39,840	30,438
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	2,186	1,181
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,318	1,076
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	2,188	1,520
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 1,550	$ 1,059

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 6,891	$ 6,311	$ 5,587

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Employee compensation and benefits	$ 20,359	$ 10,920
Accrued research and development	16,979	11,008
Accrued legal and professional expenses	3,100	1,876
Accrued other	2,871	1,750
Total accrued expenses	$ 43,309	$ 25,554

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of the Federal Statutory Income Tax Rate and the Company's Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)	(21.00%)
State income taxes	16.60%	(7.40%)	(8.90%)
Research and development tax credits	8.70%	(1.80%)	(5.10%)
Stock-based compensation	(16.80%)	(1.30%)	1.20%
162m	0.002
Change in valuation allowance	62.90%	31.50%	33.80%

Income Taxes - Summary of Compa

Income Taxes - Summary of Company's Net Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Intangibles, including acquired in-process research and development	$ 1,010	$ 981
Capitalized start-up costs	334	378
Net operating loss carryforwards	216,629	101,807
Research and development credit carryforwards	61,698	23,166
Operating lease liability	20,055	10,713
Deferred revenue	13,922	4,680
Equity-based compensation	7,774	8,574
Accruals and allowances	3,718	2,200
Prepaid Rent	1,393
Equity investment adjustments	359
Gross deferred tax assets	326,892	152,499
Deferred tax asset valuation allowance	(304,781)	(140,868)
Total deferred tax assets	22,111	11,631
Deferred tax liabilities:
Fixed assets	(669)	(970)
Operating lease right-of-use assets	21,442	(10,661)
Total deferred tax liabilities	(22,111)	(11,631)
Net deferred tax asset (liability)	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 27, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Tax Benefit [Line Items]
Net operating loss carryforwards, federal		$ 800,500	$ 372,500
Taxable Income available for the period the loss was generated		20 years
Percentage of Coronavirus Aid Relief and Economic Security Act removes the limit for taxable years	80.00%
Coronavirus Aid Relief and Economic Security Act allows net operating losses carryback period	5 years
Increase in valuation allowance		$ 163,900	42,400	$ 34,500
Research and development and other credit		61,698	23,166
Unrecognized tax benefits		$ 0
Operating Loss Carryforward Indefinitely Begins to Expire in 2034 [Member]
Income Tax Benefit [Line Items]
Net operating loss carryover, percentage of taxable income		100.00%
Operating Loss Carryforward Indefinitely [Member]
Income Tax Benefit [Line Items]
Net operating loss carryover, percentage of taxable income		80.00%
Federal [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards, expiration date description		begin to expire in 2034
Net operating loss carryforwards, begins to expiring year		2034
Tax credit carryforwards, expiration date description		begin to expire in 2034
Tax credit carryforwards, begins to expiring year		2034
Federal [Member] | Operating Loss Carryforward Indefinitely Begins to Expire in 2034 [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards, with expiration date		$ 37,200
Federal [Member] | Operating Loss Carryforward Indefinitely [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards with no expiration date		763,300
Federal [Member] | Tax Carryforwards Begin to Expire in 2034 [Member]
Income Tax Benefit [Line Items]
Tax credit carryforwards, with expiration date		$ 37,900	15,000
State [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards, expiration date description		begin to expire in 2034.
Net operating loss carryforwards, begins to expiring year		2034
Research and development and other credit		$ 30,200	10,300
Research and development tax credits, expiration year		2029
Research and development tax credits, expiration date description		begin to expire in 2029
State [Member] | Operating Loss Carryforward Begin to Expire In 2034 [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards, with expiration date		$ 767,800	$ 373,100

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Millions	Jun. 16, 2021USD ($)
Caribou Leaseback Agreement [Member]
Commitments And Contingencies [Line Items]
Deferred revenue additions	$ 1

Collaborations and Other Arrang

Collaborations and Other Arrangements - Summary of Changes in Accounts Receivable and Contract Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Accounts receivable:
Accounts receivable, Balance at Beginning of Period	$ 2,130	$ 4,620
Accounts receivable, Additions	7,559	103,116
Accounts receivable, Deductions	(7,658)	(105,606)
Accounts receivable, Balance at End of Period	2,031	2,130
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	73,931	28,810
Deferred revenue, Additions	84,659	87,477
Deferred revenue, Deductions	(31,355)	(42,356)
Deferred revenue, Balance at End of Period	$ 127,235	$ 73,931

Collaborations and Other Arra_2

Collaborations and Other Arrangements- Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Amounts included in the contract liability at the beginning of the period	$ 22,544	$ 11,571

Collaborations and Other Arra_3

Collaborations and Other Arrangements - Additional Information (Detail) - USD ($)		1 Months Ended				12 Months Ended			69 Months Ended
		Oct. 31, 2021	Sep. 30, 2021	Jul. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021	Jul. 30, 2021
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Expenses incurred to obtain collaboration agreements and costs to fulfill contracts						$ 0
Costs to obtain or fulfill contract capitalized						$ 0			$ 0
Common stock, par value						$ 0.0001	$ 0.0001		$ 0.0001
Collaboration revenue	[1]					$ 33,053,000	$ 57,994,000	$ 43,103,000
Deferred revenue						$ 127,235,000	73,931,000	28,810,000	$ 127,235,000
Development costs and pay royalties						50.00%
Shares of Series A2 Preferred Stock						83,316			83,316
Equity Ownership						11.00%			11.00%
Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
opt-in fee						$ 20,000
Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
opt-in fee						10,000
Second CoDevelopment and CoPromotion Agreement [Member] | New CAR T-Cell Therapy [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration Payment				$ 30,000,000
AvenCell Member
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions						2,900,000
Collaboration revenue						5,900,000
Deferred revenue						$ 54,100,000			$ 54,100,000
Equity Method Investment, Ownership Percentage						33.33%			33.33%
AvenCell Member | New CAR T-Cell Therapy [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity Method Investment, Ownership Percentage										33.33%
AvenCell Member | NewCo Co/Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration transaction price						$ 62,900,000
AvenCell Member | AvenCell Co/Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						200,000
Deferred revenue						2,900,000			$ 2,900,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate transaction price remaining to be recognized						51,400,000			51,400,000
Accounts receivable						2,000,000	2,100,000		2,000,000
Deferred revenue						51,400,000	73,900,000		51,400,000
Regeneron Pharmaceuticals Inc. [Member] | Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						2,700,000	0	0
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions									145,000,000
Collaboration revenue						$ 25,700,000	53,000,000	24,600,000	149,000,000
Aggregate transaction price remaining to be recognized, period						Through December 31, 2021
Payments due						$ 5,900,000	10,700,000	12,000,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member] | Research and Development Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue									37,900,000
Novartis [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Strategic collaboration agreement amended date						2018-12
One Time Payment To Novartis						$ 10,000,000
Novartis [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			$ 300,000		$ 5,000	62,400,000		$ 18,500,000
Deferred revenue						0	$ 0		0
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue						14,800,000			14,800,000
Collaboration transaction price		$ 14,800,000
Collaboration description		For product candidates the Company chooses to option, it will pay an opt-in fee between $10.0 million and $20.0 million depending on the stage of development of the target, reimburse certain costs, share in 50% of development costs and pay royalties to SparingVision on U.S. sales.
Development and commercial milestone payment to be received		$ 200,000,000
Kyverna [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration Payment						5,000,000
Deferred revenue						7,000,000			$ 7,000,000
Collaboration transaction price						7,000,000
Development Costs and Future Net Profit						$ 50,000
[1]	(1) Including the following revenue from related party (see Notes 9 and 15): $ 6,072 $ - $ -

Equity-Method Investment - Addi

Equity-Method Investment - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Oct. 31, 2021	Jul. 30, 2021	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity method investment			$ 58,131,000	$ 58,131,000	$ 0
Loss from equity method investments				1,325,000	$ 0	$ 0
AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment			$ 58,100,000	$ 58,100,000
Equity Method Investment, Ownership Percentage			33.33%	33.33%
Investment Owned, at Fair Value		$ 62,900,000
Loss from equity method investments				$ 2,900,000
Investments in and Advances to Affiliates, at Fair Value, Gross Reductions			$ 1,800,000
AvenCell [Member] | Measurement Input, Option Volatility [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage		76.00%
AvenCell [Member] | Measurement Input Option Subsequent Financing [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage		75.00%
AvenCell [Member] | Measurement Input, Discount for Lack of Marketability [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage		11.00%
Sparing Vision [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, at Fair Value	$ 14,800,000
Sparing Vision [Member] | Series A2 Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Number of preferred stock received	83,316
Sparing Vision [Member] | Measurement Input, Option Volatility [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage	90.00%
Sparing Vision [Member] | Measurement Input Option, Rate of Return [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage	65.00%
Kyverna Therapeutics Inc [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, at Fair Value			$ 10,000,000	$ 10,000,000
Kyverna Therapeutics Inc [Member] | Series B Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Number of preferred stock received				3,739,515
Fair value of stock received				$ 7,000
Number of stock additionally invested				1,602,649
Cash consideration received on sale of common stock				$ 3,000,000
Preferred Stock Purchase Agreement [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		33.33%
Preferred Stock Purchase Agreement [Member] | Cellex and BXLS [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		66.67%

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Mar. 31, 2021USD ($)USD_per_sqft

Nov. 30, 2020

Sep. 30, 2020USD ($)

Apr. 30, 2019USD ($)

Mar. 31, 2019

Jan. 31, 2016USD ($)

Oct. 31, 2014USD ($)

Dec. 31, 2020USD ($)

Mar. 31, 2020USD ($)

Mar. 31, 2019

Dec. 31, 2021USD ($)ft²USD_per_sqft

Dec. 31, 2020USD ($)

Dec. 31, 2019USD ($)

Sep. 30, 2021USD ($)

Jun. 30, 2021USD ($)

Lessee Lease Description [Line Items]

Increase in operating lease right-of-use assets

$ 400

$ (9,349)

$ (6,457)

$ (5,728)

Increase in operating lease, liability

$ 400

Operating lease right-of-use assets

$ 39,114

79,143

$ 39,114

$ 1,400

Operating lease, liability

$ 74,023

Operating lease, existence of option to extend

true

130 Brookline Street [Member]

Lessee Lease Description [Line Items]

Operating lease, description

In October 2014, the Company entered into an agreement to lease office and laboratory space at 130 Brookline Street (the “130 Brookline Lease”) in Cambridge, Massachusetts under an operating lease agreement with a term through January 2020, with an option to extend the term of the lease for an additional five-year period. In April 2019, the lease was amended to extend the term for the additional five-year period, through January 2025.

Operating lease expiration

2020-01

Lessee operating lease extended expiration date

Jan. 31, 2025

Operating lease, options to extend

option to extend the term of the lease for an additional five-year period. In April 2019, the lease was amended to extend the term for the additional five-year period, through January 2025

Operating lease, renewal term

5 years

Lessee operating sublease option to extend

two options to extend the agreement by one year each, for a total option period of up to two years.

Operating sublease expiration

2021-04

Operating sublease, existence of option to extend

true

Operating lease right-of-use assets

$ 1,300

Operating lease, liability

$ 1,300

Operating lease, existence of option to terminate

true

130 Brookline Street [Member] | Maximum [Member]

Lessee Lease Description [Line Items]

Operating sublease, renewal term

2 years

130 Brookline Street [Member] | Second Amendment [Member]

Lessee Lease Description [Line Items]

Operating lease, description

In March 2020, the Company entered into a second amendment to the 130 Brookline Lease (the “130 Brookline Lease Second Amendment”). The 130 Brookline Lease Second Amendment extends the term of the 130 Brookline Lease by approximately six years through January 31, 2031.

Lessee operating lease extended expiration date

Jan. 31, 2031

Operating lease, existence of option to extend

true

Operating lease, options to extend

an option to extend the lease for two consecutive five-year terms.

Operating lease, renewal term

6 years

Increase in operating lease right-of-use assets

$ 7,300

Increase in operating lease, liability

$ 7,300

130 Brookline Street [Member] | Other Assets [Member]

Lessee Lease Description [Line Items]

Lease security deposit

$ 300

40 Erie Street [Member]

Lessee Lease Description [Line Items]

Operating lease, description

In January 2016, the Company entered into a ten-year agreement to lease office and laboratory space at 40 Erie Street (the “40 Erie Lease”) in Cambridge, Massachusetts under an operating lease agreement, with an option to terminate the lease at the end of the sixth year and an option to extend the term of the lease for an additional three years.

Operating lease, existence of option to extend

true

Operating lease, options to extend

an option to extend the term of the lease for an additional three years.

Operating lease, renewal term

3 years

Operating lease, term of contract

10 years

Operating lease, existence of option to terminate

true

Operating lease, option to terminate

option to terminate the lease at the end of the sixth year

Operating lease, terminate term

6 years

40 Erie Street [Member] | Second Amendment [Member]

Lessee Lease Description [Line Items]

Operating lease, description

In November 2020, the Company entered into a second amendment to the 40 Erie Lease (the “40 Erie Lease Second Amendment”) which provides the Company with a right of first offer with respect to any space that becomes available at the 40 Erie Street building, and in consideration for this right the Company agreed to nullify the option to terminate the lease at the end of the sixth year that was included in the 40 Erie Lease.

Operating lease, existence of option to extend

true

Increase in operating lease right-of-use assets

18,500

Increase in operating lease, liability

$ 18,500

Operating lease, option to terminate

option to terminate the lease at the end of the sixth year

Operating lease, terminate term

6 years

40 Erie Street [Member] | Other Assets [Member]

Lessee Lease Description [Line Items]

Lease security deposit

$ 2,200

Albany Lease [Member]

Lessee Lease Description [Line Items]

Operating lease right-of-use assets

$ 40,400

Operating lease, liability

$ 34,800

Area of space leased | ft²

39,000

Operating lease, description

In March 2020, the Company entered into an agreement to lease approximately 39,000 square feet of office and laboratory space at 281 Albany Street in Cambridge, Massachusetts under an operating lease agreement (the “281 Albany Lease”).

Term of lease

10 years

Base rent per square foot for first year | USD_per_sqft

99

Base rent per square foot for last year | USD_per_sqft

128.87

Amount receivable on cost of construction and tenant improvement

$ 4,400

Operating lease, existence of option to extend

true

Operating lease, options to extend

The Company has the option to extend the 281 Albany Lease for two successive five-year terms

Incremental borrowing rate

5.52%

Prepaid lease payments

$ 5,600

Albany Lease [Member] | Other Assets [Member]

Lessee Lease Description [Line Items]

Letter of credit

$ 1,900

Tudor Lease Member

Lessee Lease Description [Line Items]

Operating lease right-of-use assets

$ 4,900

Operating lease, liability

$ 4,900

Area of space leased | ft²

13,662

Operating lease, description

In July 2021, the Company entered into an agreement to lease 13,662 square feet of office space at 17 Tudor Street in Cambridge, Massachusetts under an operating lease agreement (the “17 Tudor Lease”). The Company’s obligation to pay rent began on November 1, 2021.

Term of lease

5 years

Base rent per square foot for first year | USD_per_sqft

74

Base rent per square foot for last year | USD_per_sqft

83.29

Operating lease, options to extend

The initial term of the 17 Tudor Lease is five years and the Company has an option to extend the 17 Tudor Lease for one three-year term.

Incremental borrowing rate

4.15%

Tudor Lease Member | Other Assets [Member]

Lessee Lease Description [Line Items]

Letter of credit

$ 200

Waltham Lease [Member]

Lessee Lease Description [Line Items]

Operating lease right-of-use assets

$ 2,500

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs and Other Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lease cost
Operating lease cost	$ 12,871	$ 8,447
Short-term lease cost	31	56
Variable lease cost	3,339	2,918
Total lease cost	16,241	11,421
Other information
Operating cash flows used for operating leases	12,641	7,495
Operating lease liabilities arising from obtaining right-of-use assets	$ 49,378	$ 26,432
Weighted average remaining lease term	7 years 2 months 12 days	6 years 8 months 12 days
Weighted average discount rate	5.50%	5.80%

Leases - Schedule of Reconcilia

Leases - Schedule of Reconciliation of Undiscounted Cash Flows for Operating Lease Liabilities / Future Minimum Lease Payments (Detail) $ in Thousands	Dec. 31, 2021USD ($)
Leases [Abstract]
2022	$ 12,929
2023	13,398
2024	12,320
2025	12,838
2026	11,544
Thereafter	28,809
Total lease payments	91,838
Less: imputed interest	(17,815)
Operating lease, liability	$ 74,023

Equity-Based Compensation - Add

Equity-Based Compensation - Additional Information (Detail) - USD ($)	1 Months Ended			12 Months Ended
	Jan. 31, 2020	May 31, 2016	May 30, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number				453,026	193,936
Weighted Average Grant Date Fair Value per Share, Granted				$ 73.81	$ 21.70	$ 0
Number of shares, cancelled				72,467
Total fair value amount, Vested				$ 14,100,000	$ 2,800,000	$ 600
Number of shares vested				119,715
Unrecognized equity-based compensation expense related to restricted stock				$ 27,100,000
Number of Shares, Granted				451,272
Acceleration resulted in additional expense				$ 47,009,000	$ 19,903,000	$ 15,091,000
Weighted average grant date fair value per share				$ 54.09	$ 9.07	$ 9.21
Total intrinsic value of stock options exercised				$ 262,000,000	$ 20,300,000	$ 2,300,000
Unrecognized compensation cost related to stock options				$ 130,300,000
Stock options outstanding				6,305,156	6,977,440
Potential dilutive securities excluded from computation of diluted net loss per common share				6,758,000	7,171,000	5,438,000
Performance-based options forfeited				700,700
Common stock, shares issued				74,485,883	66,234,056
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of unrecognized compensation costs				2 years 9 months 18 days
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period	3 years
Weighted Average Grant Date Fair Value per Share, Granted	$ 15.05
Number of Shares, Granted	181,020
RSUs vested number					58,870
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of unrecognized compensation costs				3 years 1 month 6 days
Satisfaction Of a Service Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vested				26,235
Development milestones | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vested				64,290
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period				3 years
Description of stock options granted under the Plan				Stock options granted under the 2015 Plan generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years, unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years.
Shares available for future issuance				2,241,278
Percentage of cumulative increase in number of shares for future issuance				4.00%
2015 Plan [Member] | First Anniversary of Original Vesting Date [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vest percentage on the first anniversary				25.00%
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of stock options granted under the Plan			The 2016 Plan allows eligible employees to purchase shares of the Company’s common stock on the last day of each predetermined six-month offering period at 85% of the lower of the fair market value per share at the beginning or end of the applicable offering period.
Shares available for future issuance				1,297,202
Weighted Average Grant Date Fair Value per Share, Granted				$ 65.51	$ 15.28	$ 12.05
Common stock, shares issued				30,897	101,911	90,581
Percentage of fair market value of common stock		85.00%
Maximum [Member] | 2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options granted				10 years
Maximum [Member] | 2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued				500,000

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Equity-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 47,009	$ 19,903	$ 15,091
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	26,712	10,202	6,986
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 20,297	$ 9,701	$ 8,105

Equity-Based Compensation - Sum

Equity-Based Compensation - Summary of Restricted Stock Activity (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Number of Shares, Unvested, Beginning balance	193,936
Number of Shares, Granted	451,272
Number of Shares, Vested	(119,715)
Number of Shares, Cancelled	(72,467)
Number of Shares, Unvested, Ending balance	453,026	193,936
Weighted Average Grant Date Fair Value per Share, Unvested, Beginning balance	$ 23.98
Weighted Average Grant Date Fair Value per Share, Granted	73.81	$ 21.70	$ 0
Weighted Average Grant Date Fair Value per Share, Vested	20.94
Weighted Average Grant Date Fair Value per Share, Cancelled	45.14
Weighted Average Grant Date Fair Value per Share, Unvested, Ending balance	$ 71.03	$ 23.98

Equity-Based Compensation - S_2

Equity-Based Compensation - Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted (Detail)	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	1.00%	0.80%	2.10%
Expected life of options	6 years	6 years	6 years
Expected volatility of underlying stock	72.90%	67.80%	68.10%
Expected dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate			2.10%
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of options	6 months	6 months	6 months
Expected dividend yield	0.00%	0.00%	0.00%
2016 Employee Stock Purchase Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.09%	1.60%	2.50%
Expected volatility of underlying stock	109.20%	98.30%	76.50%
2016 Employee Stock Purchase Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.05%	0.17%
Expected volatility of underlying stock	77.50%	53.40%	62.90%

Equity-Based Compensation - S_3

Equity-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)$ / sharesshares
Share-based Payment Arrangement [Abstract]
Number of Options, Outstanding, Beginning Balance | shares	6,977,440
Number of options, Granted | shares	2,729,302
Number of options, Exercised | shares	(2,700,886)
Number of options, Forfeited | shares	(700,700)
Number of Options, Outstanding, Ending Balance | shares	6,305,156
Number of Options, Exercisable | shares	2,227,760
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance | $ / shares	$ 15.43
Weighted Average Exercise Price per Share, Granted | $ / shares	84.16
Weighted Average Exercise Price per Share, Exercised | $ / shares	15.22
Weighted Average Exercise Price per Share, Forfeited | $ / shares	30.74
Weighted Average Exercise Price per Share, Outstanding, Ending Balance | $ / shares	43.57
Weighted Average Exercise Price per Share, Exercisable | $ / shares	$ 16.37
Weighted Average Remaining Contractual Term, Outstanding	7 years 4 months 17 days
Weighted Average Remaining Contractual Term, Exercisable	5 years 5 months 4 days
Aggregate Intrinsic Value, Outstanding | $	$ 492,968
Aggregate Intrinsic Value, Exercisable | $	$ 226,941

Loss Per Share - Schedule of Ba

Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net loss	$ (267,892)	$ (134,231)	$ (99,533)
Weighted average shares outstanding, basic and diluted	70,894	55,987	47,247
Net loss per share, basic and diluted	$ (3.78)	$ (2.40)	$ (2.11)

Loss Per Share - Potential Dilu

Loss Per Share - Potential Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share (Detail) - 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]
Potential dilutive securities excluded from computation of diluted net loss per common share	6,758	7,171	5,438
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	453	194	72
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	6,305	6,977	5,366

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Jul. 02, 2021	Jun. 29, 2021	Dec. 04, 2020	Dec. 01, 2020	Jun. 05, 2020	Jun. 01, 2020	May 31, 2020	Aug. 31, 2019	Oct. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Common stock, par value										$ 0.0001	$ 0.0001
Proceeds from common stock offering										$ 1,817,900,000
Common Stock, Par or Stated Value Per Share										$ 0.0001	$ 0.0001
Regeneron Pharmaceuticals Inc. [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering										$ 0	$ 12,580,000	$ 0
Issuance of common stock											$ 12,580,000
2018 Sales Agreement [Member]
Class Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues									5,890,648
Common stock price per share									$ 16.98
Proceeds from common stock offering									$ 96,400,000
Percentage of gross proceeds from common stock as sales agent cash commission										3.00%
Shares Issued, Price Per Share									$ 16.98
2018 Sales Agreement [Member] | General and Administrative Expenses [Member]
Class Of Stock [Line Items]
Legal accounting and other fees									$ 600,000
2018 Sales Agreement [Member] | Maximum [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering									$ 100,000,000
2019 Sales Agreement [Member]
Class Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues										641,709	2,270,161	287,231
Common stock price per share										$ 72.79	$ 22.53	$ 16.48
Proceeds from common stock offering										$ 45,300,000	$ 49,500	$ 4,400,000
Percentage of gross proceeds from common stock as sales agent cash commission									3.00%
Proceeds from common stock offering										$ 47,400,000
Shares Issued, Price Per Share										$ 72.79	$ 22.53	$ 16.48
2019 Sales Agreement [Member] | General and Administrative Expenses [Member]
Class Of Stock [Line Items]
Legal accounting and other fees										$ 100	$ 200,000	$ 200,000
2019 Sales Agreement [Member] | Maximum [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering								$ 150,000
Follow On Public Offering
Class Of Stock [Line Items]
Proceeds from common stock offering										648,315,000	296,607,000	$ 0
Issuance of common stock										$ 648,315,000	$ 296,607,000
Follow On Public Offering | Underwriting Agreement [Member]
Class Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues		4,758,620		5,513,699		6,301,370
Common stock, par value		$ 0.0001		$ 0.0001		$ 0.0001
Shares available for future issuance		620,689		719,178		821,917
Common stock price per share		$ 145		$ 36.50		$ 18.25
Proceeds from common stock offering	$ 648,300,000		$ 188,900,000		$ 107,700,000
Shares Issued, Price Per Share		145		36.50		18.25
Common Stock, Par or Stated Value Per Share		$ 0.0001		$ 0.0001		$ 0.0001
Private Placement [Member] | 2020 Stock Purchase Agreement [Member] | Regeneron Pharmaceuticals Inc. [Member]
Class Of Stock [Line Items]
Stock Issued During Period, Shares, New Issues							925,218
Common stock, par value							$ 0.0001
Cash consideration received on sale of common stock							$ 30,000,000
Sale of stock, price per share							$ 32.42
Percentage of premium over volume-weighted average trading price of common stock during 30-day period prior to closing of equity transaction							100.00%
Issuance of common stock							$ 12,600,000
Sale of Stock, Consideration Received on Transaction							$ 30,000,000
Common Stock, Par or Stated Value Per Share							$ 0.0001

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Deferred revenue	$ 127,235,000	$ 73,931,000	$ 28,810,000
Deferred revenue current	63,759,000	22,544,000
Deferred revenue non-current	63,476,000	51,387,000
Investments and Other Noncurrent Assets	$ 29,558,000	$ 4,748,000
AvencellLca
Related Party Transaction [Line Items]
Investment Percentage	33.33%
Deferred revenue	$ 54,100
Deferred revenue current	34,200
Deferred revenue non-current	19,900
Revenue	5,900
AvencellCoCo
Related Party Transaction [Line Items]
Revenue	200
KyvernaLca
Related Party Transaction [Line Items]
Investments and Other Noncurrent Assets	$ 10,000

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Detail) - 401(k) plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution of employee contribution, percent	50.00%
Employer matching contribution, percent	6.00%
Employer discretionary contribution amount	$ 1.6	$ 1.1	$ 0.8

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) $ / shares in Units, $ in Millions	Feb. 18, 2022ft²USD_per_sqft	Feb. 12, 2022USD ($)	Feb. 02, 2022USD ($)$ / sharesshares	Jan. 01, 2022USD_per_sqft	Oct. 31, 2021USD ($)	Jan. 31, 2022ft²USD_per_sqft	Dec. 31, 2021$ / sharesshares	Dec. 31, 2022	Dec. 31, 2020$ / sharesshares
Subsequent Event [Line Items]
Operating lease, existence of option to extend							true
Common stock, par value | $ / shares							$ 0.0001		$ 0.0001
Common stock, shares issued | shares							74,485,883		66,234,056
Sparing Vision [Member]
Subsequent Event [Line Items]
Development and commercial milestone payment to be received					$ 200
Lease [Member]
Subsequent Event [Line Items]
Operating lease, description							In January 2022, the Company entered into a Lease Agreement (the “Lease”) with the Massachusetts Institute of Technology (the “Landlord”) for office and laboratory space located at 730 Main Street, Cambridge, Massachusetts (the “Premises”). Under the terms of the Lease, the Company will lease approximately 38,000 square feet at the Premises, which will supplement the Company’s current leased premises in Cambridge, Massachusetts. The Lease, including the obligation to pay rent, is expected to commence on October 22, 2022 (the “Commencement Date”).
Operating lease, options to extend							The Company has the option to extend the Lease for one five-year term
Subsequent Event [Member] | Sparing Vision [Member]
Subsequent Event [Line Items]
Development and commercial milestone payment to be received		$ 184
Subsequent Event [Member] | Lease [Member]
Subsequent Event [Line Items]
Area Of Space Leased | ft²	140,000					38,000
Term of lease								10 years
Base rent per square foot for first year | USD_per_sqft	73.50			130
Base rent per square foot for last year | USD_per_sqft						169.62
Subsequent Event [Member] | Rewrite Holders
Subsequent Event [Line Items]
Upfront Consideration Payable In Cash			$ 45
milestone payments			$ 155
Common stock, par value | $ / shares			$ 0.0001
Common stock, shares issued | shares			25
Cash			$ 130