Intellia Therapeutics (NTLA) 10-K 22 Feb 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 16, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
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		96,106,405
Entity Public Float			$ 3,565,071,688
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 2024 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, 2023. 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
Document Financial Statement Error Correction [Flag]	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 226,748	$ 523,506
Marketable securities	685,475	669,116
Accounts receivable ($0.2 million and $0.3 million, respectively,from related party)	36,456	3,768
Prepaid expenses and other current assets	49,651	20,407
Total current assets	998,330	1,216,797
Marketable securities - noncurrent	99,864	69,338
Property and equipment, net	32,760	27,921
Operating lease right-of-use assets	115,375	133,076
Equity method investment	11,765	32,455
Investments and other assets	42,883	40,527
Total Assets	1,300,977	1,520,114
Current Liabilities:
Accounts payable	7,452	5,154
Accrued expenses ($1.0 million and $1.6 million, respectively, from related party)	67,017	60,876
Current portion of operating lease liability	18,599	16,685
Current portion of deferred revenue ($0 and $19.9 million, respectively,from related party)	22,140	43,839
Total current liabilities	115,208	126,554
Deferred revenue, net of current portion	38,853	19,932
Long-term operating lease liability	96,747	114,018
Contingent consideration liability	0	24,026
Total liabilities	250,808	284,530
Commitments and contingencies (Note 8)
Stockholders’ Equity:
Common stock, $0.0001 par value; 240,000,000 and 120,000,000 shares authorized at December 31, 2023 and December 31, 2022, respectively;92,997,158 and 87,103,007 shares issued and outstanding at December 31, 2023 and December 31, 2022, respectively	9	9
Additional paid-in capital	2,710,797	2,420,223
Accumulated other comprehensive loss	(2,258)	(7,461)
Accumulated deficit	(1,658,379)	(1,177,187)
Total stockholders’ equity	1,050,169	1,235,584
Total Liabilities and Stockholders’ Equity	$ 1,300,977	$ 1,520,114

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accounts receivable, related party	$ 36,456	$ 3,768
Current portion of deferred revenue, related party	$ 0	$ 19,900
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	240,000,000	120,000,000
Common stock, shares issued	92,997,158	87,103,007
Common stock, shares outstanding	92,997,158	87,103,007
Related Party [Member]
Accounts receivable, related party	$ 200	$ 300
Accrued expenses, related party	$ 1,000	$ 1,600

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Collaboration revenue	$ 36,275	$ 52,121	$ 33,053
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 435,069	$ 419,979	$ 229,807
General and administrative	116,497	90,306	71,096
Total operating expenses	551,566	510,285	300,903
Operating loss	(515,291)	(458,164)	(267,850)
Other income (expense), net:
Interest income	49,832	8,542	1,283
Loss from equity method investments	(15,633)	(11,079)	(1,325)
Change in fair value of contingent consideration	(100)	(13,485)	0
Total other income (expense), net	34,099	(16,022)	(42)
Net loss	$ (481,192)	$ (474,186)	$ (267,892)
Net Loss Per Share, Basic	$ (5.42)	$ (6.16)	$ (3.78)
Net Loss Per Share, Diluted	$ (5.42)	$ (6.16)	$ (3.78)
Weighted average shares outstanding, basic	88,770	76,972	70,894
Weighted average shares outstanding, diluted	88,770	76,972	70,894
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	$ 3,635	$ (1,637)	$ (2,126)
Other comprehensive gain (loss) from equity method investment	1,568	(3,192)	(507)
Comprehensive loss	$ (475,989)	$ (479,015)	$ (270,525)

Consolidated Statements of Op_2

Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenue from related party	$ 12,832	$ 21,134	$ 6,072

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	2022 Sales Agreement [Member]	Follow On Public Offering	At The Market Offerings	At The Market Offerings 2019 Sales Agreement [Member]	At The Market Offerings 2022 Sales Agreement [Member]	Common Stock	Common Stock Follow On Public Offering	Common Stock At The Market Offerings	Common Stock At The Market Offerings 2019 Sales Agreement [Member]	Common Stock At The Market Offerings 2022 Sales Agreement [Member]	Additional Paid-In Capital	Additional Paid-In Capital Follow On Public Offering	Additional Paid-In Capital At The Market Offerings	Additional Paid-In Capital At The Market Offerings 2019 Sales Agreement [Member]	Additional Paid-In Capital At The Market Offerings 2022 Sales Agreement [Member]	Accumulated Other Comprehensive Income	Retained Earnings
Beginning balance at Dec. 31, 2020	$ 527,072						$ 7					$ 962,173					$ 1	$ (435,109)
Beginning balance, shares at Dec. 31, 2020							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
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
Stock-based compensation	47,009											47,009
Other comprehensive loss - unrealized gain (loss) on marketable securities	(2,126)																(2,126)
Other comprehensive loss - equity method investment	(507)																(507)
Net Income (Loss)	(267,892)																	(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
Issuance of common stock			$ 337,892		$ 38,886	$ 189,011		$ 1		$ 1			$ 337,891		$ 38,885	$ 189,011
Issuance of common stock, shares		3,395,339						7,532,751		579,788	3,395,339
Exercise of stock options	14,517											14,517
Exercise of stock options, shares							883,954
Vesting of restricted stock units, shares							147,674
Issuance of shares under employee stock purchase plan	2,649											2,649
Issuance of shares under employee stock purchase plan, shares							77,618
Stock-based compensation	91,400											91,400
Other comprehensive loss - unrealized gain (loss) on marketable securities	(1,637)																(1,637)
Other comprehensive loss - equity method investment	(3,192)																(3,192)
Net Income (Loss)	(474,186)																	(474,186)
Ending balance at Dec. 31, 2022	$ 1,235,584						$ 9					2,420,223					(7,461)	(1,177,187)
Ending balance, shares at Dec. 31, 2022	87,103,007						87,103,007
Issuance of common stock						$ 121,870										$ 121,870
Issuance of common stock, shares		4,122,824									4,122,824
Contingent consideration paid, shares							567,045
Contingent consideration paid	$ 24,126											24,126
Exercise of stock options	$ 6,599											6,599
Exercise of stock options, shares	385,130						385,130
Vesting of restricted stock units, shares							677,055
Issuance of shares under employee stock purchase plan	$ 3,929											3,929
Issuance of shares under employee stock purchase plan, shares							142,097
Stock-based compensation	134,050											134,050
Other comprehensive loss - unrealized gain (loss) on marketable securities	3,635																3,635
Other comprehensive loss - equity method investment	1,568																1,568
Net Income (Loss)	(481,192)																	(481,192)
Ending balance at Dec. 31, 2023	$ 1,050,169						$ 9					$ 2,710,797					$ (2,258)	$ (1,658,379)
Ending balance, shares at Dec. 31, 2023	92,997,158						92,997,158

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
At The Market Offerings
Stock issuance cost			$ 52
At The Market Offerings | 2019 Sales Agreement [Member]
Stock issuance cost		$ 164
At The Market Offerings | 2022 Sales Agreement [Member]
Stock issuance cost	$ 376	12,500
Follow On Public Offering
Stock issuance cost		$ 253	$ 284

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (481,192)	$ (474,186)	$ (267,892)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	8,976	7,572	6,891
Loss (gain) on disposal of property and equipment	72	(162)	0
Stock-based compensation	134,050	91,400	47,009
(Accretion) amortization of investment discounts and premiums	(25,897)	4,003	7,604
Loss from equity method investment	15,633	11,079	1,325
Deferral of equity method investment intra-entity profit on sales	6,624	11,405	2,937
Change in fair value of contingent consideration	100	13,485	0
In-process research and development expense	0	55,990	0
Changes in operating assets and liabilities:
Accounts receivable	(32,688)	(1,737)	99
Prepaid expenses and other current assets	(27,168)	(2,160)	(9,798)
Operating lease right-of-use assets	19,011	13,121	9,349
Other assets	(707)	(1,091)	117
Accounts payable	2,522	(4,584)	529
Accrued expenses	6,024	15,924	17,260
Deferred revenue	(2,778)	(63,464)	(31,355)
Operating lease liabilities	(16,668)	(9,882)	(9,105)
Net cash used in operating activities	(394,086)	(333,287)	(225,030)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(13,985)	(13,558)	(12,756)
Purchases of marketable securities	(904,464)	(429,032)	(1,020,620)
Maturities of marketable securities	887,102	647,581	485,598
Proceeds from sale of property and equipment	0	150	0
Acquired in-process research and development, net of cash acquired of $287	0	(44,832)	0
Investment in Kyverna Therapeutics, Inc.	0	0	(3,000)
Net cash (used in) provided by investing activities	(31,347)	160,309	(550,778)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from options exercised	6,599	14,517	41,094
Issuance of shares through employee stock purchase plan	3,929	2,649	2,024
Net cash provided by financing activities	130,323	582,955	736,688
Net (decrease) increase in cash and cash equivalents and restricted cash equivalents	(295,110)	409,977	(39,120)
Cash, cash equivalents and restricted cash equivalents, beginning of period	535,463	125,486	164,606
Cash, cash equivalents and restricted cash equivalents, end of period	240,353	535,463	125,486
Reconciliation of cash, cash equivalents and restricted cash equivalents to consolidated balance sheet:
Cash and cash equivalents	226,748	523,506	123,406
Restricted cash equivalents, included in investments and other assets	13,605	11,957	2,080
Total cash, cash equivalents and restricted cash equivalents	240,353	535,463	125,486
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Purchases of property and equipment unpaid at period end	1,525	1,623	667
Shares issued for Rewrite contingent consideration	24,126	0	0
Right-of-use assets acquired under operating leases	1,311	67,053	49,378
Proceeds from at-the-market offerings unpaid at period end	2,075	0	0
Contingent consideration liability assumed in asset acquisition	0	10,541	0
Non-cash trade-in of property and equipment	0	200	0
AvenCell Therapeutics, Inc [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Loss from equity method investment	(6,600)	(11,400)	(2,900)
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property	0	0	62,900
Sparing Vision SAS [Member]
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property	0	0	14,759
Kyverna Therapeutics, Inc. [Member]
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property	0	0	7,000
Follow On Public Offering
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common stock	0	337,892	648,315
At The Market Offerings
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common stock	$ 119,795	$ 227,897	$ 45,255

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Net of cash acquired	$ 287

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (481,192)	$ (474,186)	$ (267,892)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Rule 10b5-1 Arrangement Modified	false
Non-Rule 10b5-1 Arrangement Modified	false

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Organization Intellia Therapeutics, Inc. (“Intellia” or the “Company”) is a leading clinical-stage gene editing company, focused on developing potentially curative therapeutics using CRISPR/Cas9-based technologies. CRISPR/Cas9, an acronym for C lustered, R egularly I nterspaced S hort P alindromic R epeats (“CRISPR”)/ C RISPR a ssociated 9 (“Cas9”), is a technology for genome editing, the process of altering selected sequences of genomic deoxyribonucleic acid (“DNA”). To fully realize the transformative potential of CRISPR/Cas9-based technologies, the Company is building a full-spectrum gene editing company, by leveraging its modular platform, to advance in vivo and ex vivo therapies for diseases with high unmet need by pursuing two primary approaches. For in vivo applications to address genetic diseases, the Company deploys CRISPR/Cas9 as the therapy. The Company’s in vivo programs use CRISPR to enable precise editing of disease-causing genes directly inside the human body. In addition, the Company is advancing ex vivo applications to address immuno-oncology and autoimmune diseases, where it uses CRISPR/Cas9 as the tool to create the engineered cell therapy. For its ex vivo programs, CRISPR/Cas9 is used to engineer human cells outside the body. The Company’s deep scientific, technical and clinical development experience, along with its robust intellectual property (“IP”) portfolio, have enabled 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 2014. The Company will require substantial additional capital to fund its research and development. The Company is subject to risks and uncertainties common to clinical-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, 2023, the Company has raised an aggregate of $ 2,534.1 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, 2023 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, 2023
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. In February 2022, the Company entered into an agreement to acquire Rewrite Therapeutics, Inc., a Delaware corporation (“Rewrite”). On the effective date of the agreement, Rewrite became a wholly owned subsidiary of the Company. In September 2022, Rewrite merged into Intellia, with Intellia the surviving entity. 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 and determination of impairment of equity and fair value method investments, contingent consideration and stock-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 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, restricted cash equivalents, marketable securities, accounts receivable, non-marketable securities, accounts payable and accrued expenses. Certain of the Company’s financial assets, including cash equivalents, restricted 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. Investments in non-marketable securities are accounted for using the measurement alternative at cost minus impairment, adjusted for changes in observable prices. 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, 2023, cash equivalents consisted of interest-bearing money market accounts, U.S. Treasury bills and other government securities. As of December 31, 2022, cash equivalents consisted of interest-bearing money market accounts and reverse purchase agreements. 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 certain of its leases. As of December 31, 2023, these restricted cash equivalents amounted to $ 13.6 million. As of December 31, 2022, these restricted cash equivalents amounted to $ 12.0 million. The letters of credit are required to be maintained throughout the term of the leases; in some cases, the Company is able to reduce the amounts held over time. These restricted cash equivalents are long-term in nature and are included in “Investments and other assets” in the Company’s consolidated balance sheets. 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. Asset Acquisitions At the time of acquisition, the Company determines if a transaction should be accounted for as a business combination or acquisition of assets. The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs, and the consideration is allocated to the items acquired based on a relative fair value methodology. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire in-process research and development with no alternative future use is charged to research and development expense at the acquisition date. Non-Marketable Equity Securities The Company periodically 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 there are any indicators of impairment, and if so determines the fair value of the investment and compares to the recorded balance, to determine if there is an impairment, 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, restricted 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, 2023, the Company’s accounts receivable were related to its collaborations with Regeneron Pharmaceuticals, Inc. (“Regeneron”), SparingVision SAS (“SparingVision”), AvenCell Therapeutics, Inc. (“AvenCell”), and Kyverna Therapeutics, Inc. (“Kyverna”). As of December 31, 2022, the Company’s accounts receivable were related to its collaborations with Regeneron, AvenCell, SparingVision and ONK Therapeutics, Ltd. (“ONK”) . 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 Shorter of useful life or remaining lease term 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. Contingent Consideration The Company accounts for contingent consideration identified in an asset acquisition, that is payable in cash and does not meet the definition of a derivative under Accounting Standard Codification (“ASC”) 815, Derivatives and Hedging , when the contingency is resolved and the consideration is paid or becomes payable. The Company accounts for contingent consideration identified in an asset acquisition that is settled in shares of common stock under ASC 480, Distinguishing Liabilities from Equity (“ASC 480”). The contingent consideration liability will be recorded at fair value at the end of each reporting period with changes in estimated fair values recorded in other (expense) income in the consolidated statements of operations and comprehensive loss. 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 “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, 2023 or 2022 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, 2023, the Company’s revenue recognized is solely 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 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 costs consist of expenses incurred in performing research and development activities, such as salaries, stock-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. Stock-Based Compensation The Company’s stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as an expense over the requisite service period. The fair value of stock option grants is estimated using the Black-Scholes option pricing model. Use of the valuation model requires management to make certain assumptions with respect to selected model inputs. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for a term consistent with the expected life of the stock options. Volatility assumptions are calculated based on historical volatility of the Company’s stock. The Company estimates the expected term of options using the simplified method. In addition, an expected dividend yield of zero is used in the option valuation model because the Company does not pay cash dividends and does not expect to pay any cash dividends in the foreseeable future. Forfeitures are recorded as they occur. The fair value of market-based restricted stock units is determined using a Monte Carlo simulation model, which uses multiple input variables to determine the probability of satisfying the market condition requirements. For awards with service conditions only, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period. For awards with service and performance-based conditions, the Company recognizes stock-based compensation expense using the graded vesting method over the requisite service period. For awards with market-based conditions, the Company recognizes stock-based compensation expense using the accelerated attribution method over the requisite service period. Estimates of stock-based compensation expense for an award with performance conditions are based on the probable outcome of the performance conditions and the cumulative effect of any changes in the probability outcomes are recorded in the period in which the changes occur. The Company classifies stock-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’s chief executive officer, its chief operating decision maker, manages the Company’ s operations as a single segment for the purpose 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, 2023 and 2022, the Company accounted for its investment in AvenCell under the equity method of accounting and no impairment charges were recognized during the years ended December 31, 2023 or 2022. Refer to Note 10 for further details. Recently Adopted Accounting Pronouncements There were no accounting pronouncements adopted by the Company in 2023. Recent Issued Accounting Pronouncements Not Yet Effective In November 2023, the FASB issued ASU No. 2023-07, “Segment Reporting - Improvements to Reportable Segment Disclosures.” The amendments require disclosure of incremental segment information on an annual and interim basis. The amendments also require companies with a single reportable segment to provide all disclosures required by this amendment and all existing segment disclosures in ASC 280, “Segment Reporting.” The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods beginning after December 15, 2024. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures. In December 2023, the FASB issued ASU No. 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” This ASU updates income tax disclosure requirements primarily by requiring specific categories and greater disaggregation within the rate reconciliation and disaggregation of income taxes paid by jurisdiction. This ASU is effective for annual periods beginning after December 15, 2024 and is applicable to the Company’s fiscal year beginning January 1, 2025, with early application permitted. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures.

Marketable Securities

Marketable Securities	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	3. Marketable Securities The following table summarizes the Company’s available-for-sale marketable securities: December 31, 2023 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 382,260 $ 302 $ ( 254 ) $ 382,308 Financial institution debt securities 246,270 92 ( 243 ) 246,119 Corporate debt securities 97,490 53 ( 135 ) 97,408 Other asset-backed securities 59,453 75 ( 24 ) 59,504 Total $ 785,473 $ 522 $ ( 656 ) $ 785,339 December 31, 2022 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 244,562 $ 62 $ ( 1,938 ) $ 242,686 Financial institution debt securities 380,891 - ( 1,030 ) 379,861 Corporate debt securities 102,059 - ( 509 ) 101,550 Other asset-backed securities 14,703 - ( 346 ) 14,357 Total $ 742,215 $ 62 $ ( 3,823 ) $ 738,454 The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. At December 31, 2023 and 2022, the balance in the Company’s accumulated other comprehensive loss 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, 2023, 2022 or 2021. The Company did not reclassify any amounts out of accumulated other comprehensive loss 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 unrealized losses as temporary in nature. The Company’ s available-for-sale securities that are classified as current 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 marketable securities 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, 2023 and 2022, the Company did no t hold any investments that matured beyond five years of the balance sheet date. Accrued interest on marketable securities is included in “Prepaid expenses and other current assets” on the Company's consolidated balance sheets.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
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. The Company’s financial assets and liabilities recognized at fair value on a recurring basis consisted of the following: Fair Value as of December 31, 2023 Total Level 1 Level 2 Level 3 Assets (In thousands) Cash equivalents and restricted cash equivalents $ 136,254 $ 136,254 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 382,308 120,556 261,752 - Financial institution debt securities 246,119 - 246,119 - Corporate debt securities 97,408 - 97,408 - Other asset-backed securities 59,504 - 59,504 - Total marketable securities 785,339 120,556 664,783 - Total $ 921,593 $ 256,810 $ 664,783 $ - Fair Value as of December 31, 2022 Total Level 1 Level 2 Level 3 Assets (In thousands) Cash equivalents and restricted cash equivalents $ 534,581 $ 534,581 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 242,686 172,939 69,747 - Financial institution debt securities 379,861 - 379,861 - Corporate debt securities 101,550 - 101,550 - Other asset-backed securities 14,357 - 14,357 - Total marketable securities 738,454 172,939 565,515 - Total $ 1,273,035 $ 707,520 $ 565,515 $ - Liabilities Contingent consideration $ 24,026 $ - $ - $ 24,026 Certain of the Company’s financial assets, including cash equivalents, restricted 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. Other financial instruments, including accounts receivable, accounts payable and accrued expense, are carried at cost, which approximates fair value due to the short duration and term to maturity. Level 3 Assets and Liabilities Equity-Method Investments The Company’s equity-method investment in AvenCell is classified as a Level 3 asset and is not included in the fair value table above as it is not valued at fair value on a recurring basis. Refer to Note 10 for further details. The carrying value of the Company’s equity-method investment as of December 31, 2023 and 2022 was $ 11.8 million and $ 32.5 million, respectively. Other Investments The Company’s other investments are classified as Level 3 assets and are not included in the fair value table above as they are not valued at fair value on a recurring basis . The Company’s investment in SparingVision was initially recorded at fair value, determined according to Level 3 inputs in the fair value hierarchy described above. The SparingVision investment is included in “Investments and other assets” on the consolidated balance sheets. This investment is accounted for using the measurement alternative at cost minus impairment adjusted for changes in observable prices. There were no changes in observable prices or impairment of this investment as of December 31, 2023 or 2022. The carrying value of the SparingVision investment was $ 14.8 million as of December 31, 2023 and 2022. Refer to Note 10 for further details. The Company’s investment in Kyverna was initially recorded at cost, which is representative of fair value. The Kyverna investment is included in “Investments and other assets” on the consolidated balance sheets. This investment is accounted for using the measurement alternative at cost minus impairment adjusted for changes in observable prices. There were no changes in observable prices or impairment of this investment as of December 31, 2023 or 2022. The carrying value of the Kyverna investment was $ 10.0 million as of December 31, 2023 and 2022. Refer to Note 10 for further details. Contingent Consideration As discussed further in Note 11, as part of its acquisition of Rewrite, the Company made a $ 25.0 million research milestone payment in February of 2023, payable in a combination of $ 0.9 million in cash and the remainder in the Company’s common stock. The milestone payable in the Company’s common stock resulted in liability classification under ASC 480. This contingent consideration liability was carried at fair value which was estimated by applying a probability-based model, which utilized inputs based on timing of achievements that were unobservable in the market. The contingent consideration liability was classified within Level 3 of the fair value hierarchy until it was settled in February of 2023. The following table reconciles the change in fair value of the contingent consideration liability based on the level 3 inputs listed below for the years ended December 31, 2023 and 2022 (in thousands): Balance at February 2, 2022 (at inception) $ 10,541 Change in fair value 13,485 Balance at December 31, 2022 24,026 Change in fair value 100 Payment of contingent consideration ( 24,126 ) Balance at December 31, 2023 $ - As of inception (February 2, 2022) As of December 31, 2022 Discount rate 7 % 10.1 % Probability of achievement 50 % 100 % Projected year of achievement 2024 2023

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following: December 31, 2023 2022 (In thousands) Laboratory equipment $ 63,970 $ 51,911 Office furniture and equipment 2,633 2,633 Computer equipment 982 1,785 Leasehold improvements 3,134 3,066 Computer software 1,902 1,725 Total property and equipment 72,621 61,120 Less: accumulated depreciation and amortization ( 39,861 ) ( 33,199 ) Property and equipment, net $ 32,760 $ 27,921 Depreciation and amortization expense was $ 9.0 million, $ 7.6 million and $ 6.9 million for the years ended December 31, 2023, 2022 and 2021, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses Accrued expenses consisted of the following: December 31, 2023 2022 (In thousands) Accrued research and development $ 27,411 $ 32,684 Employee compensation and benefits 26,615 21,778 Accrued legal and professional expenses 2,063 1,457 Accrued construction costs 6,891 - Accrued other 4,037 4,957 Total accrued expenses $ 67,017 $ 60,876

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
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, 2023 2022 2021 Federal statutory income tax rate ( 21.0 )% ( 21.0 )% ( 21.0 )% State income taxes ( 8.6 ) ( 8.3 ) ( 16.6 ) Research and development tax credits ( 6.9 ) ( 5.3 ) ( 8.7 ) Stock-based compensation 1.6 ( 0.1 ) ( 16.8 ) Non-deductible officers' compensation - 0.1 0.2 In-process research and development - 2.5 - Change in valuation allowance 34.9 32.1 62.9 Effective income tax rate — % — % — % The Company’s net deferred tax assets (liabilities) consisted of the following: December 31, 2023 2022 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 258,664 $ 229,375 Research and development credit carryforwards 151,333 101,326 Section 174 capitalized research 150,993 78,873 Operating lease liability 31,183 35,386 Deferred revenue 9,633 13,189 Stock-based compensation 30,408 22,512 Accruals and allowances 6,244 4,968 Prepaid rent 1,190 1,367 Equity investment adjustments 7,580 3,358 Intangibles, including in-process research and development 1,017 930 Capitalized start-up costs 249 296 Gross deferred tax assets 648,494 491,580 Deferred tax asset valuation allowance ( 616,082 ) ( 454,793 ) Total deferred tax assets 32,412 36,787 Deferred tax liabilities: Fixed assets ( 1,221 ) ( 759 ) Operating lease right-of-use assets ( 31,191 ) ( 36,028 ) Total deferred tax liabilities ( 32,412 ) ( 36,787 ) Net deferred tax asset (liability) $ - $ - The Tax Cuts and Jobs Act (“TCJA” ) requires taxpayers to capitalize and amortize, rather than deduct, research and development expenditures under section 174 for tax years beginning after December 31, 2021. These rules became effective for the Company during the year ended December 31, 2022. As a result, the Company has capitalized research and development costs of $ 322.6 million and $ 365.8 million for the years ended December 31, 2022 and December 31, 2023, respectively. The Company will amortize these costs for tax purposes over 5 years if the research and development was performed in the U.S. and over 15 years if the research and development was performed outside the U.S. As of December 31, 2023 and 2022, the Company had federal net operating loss carryforwards of $ 954.0 million and $ 852.1 million, respectively, which may be available to offset future income tax liabilities. Approximately $ 36.9 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 $ 917.1 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. As of December 31, 2023 and 2022, the Company also had state net operating loss carryforwards of $ 922.8 million and $ 797.8 million, respectively, which may be available to offset future income tax liabilities and begin to expire in 2034 . As of December 31, 2023 and 2022, the Company had federal tax credit carryforwards of approximately $ 100.7 million and $ 63.4 million, respectively, which begin to expire in 2034 . As of December 31, 2023 and 2022, the Company had state research and development and other credit carryforwards of approximately $ 64.1 million and $ 48.0 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, 2023 and 2022. The valuation allowance increased by $ 161.3 million in 2023, $ 150.0 million in 2022, and $ 163.9 million in 2021. Ownership changes may limit the amount of net operating loss carryforwards or research and development tax credit carryforwards that can be utilized to offset future taxable income or tax liability. In general, an ownership change, as defined by Sections 382 and 383 of the Internal Revenue Code of 1986, as amended (the “Code”), results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50% over a three-year period. If the Company has experienced a change of control, utilization of the net operating loss carryforwards or research and development tax credit carryforwards would be subject to an annual limitation under Section 382 and 383 of the Code. Any limitation may result in expiration of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization. During 2022, the Company completed an assessment of the available net operating loss carryforwards and other tax attributes under Section 382 that covered the period from inception through December 31, 2022. The analysis did not result in a material limitation to the Company’s tax attributes and the results of this analysis are reflected herein. The Company has not completed an analysis through December 31, 2023. To the extent there was a change in control during 2023, the Company's tax attributes could be subject to limitation. However, a full valuation allowance has been provided against the deferred tax assets related to 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. As of December 31, 2023 , the Company had no t identified any unrecognized tax benefits. The Company will recognize interest and/or penalties related to uncertain tax benefits in income tax expense if they arise. 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 2020 through present. To the extent that the Company has tax attribute carryforwards, the tax year in which the attributes were generated may still be adjusted upon examination by the Internal Revenue Service or State taxing authorities to the extent utilized in a future period. The returns in these jurisdictions since inception remain open for examination; however, there are currently no pending tax examinations.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Litigation From time to time, the Company is involved in legal and administrative proceedings and claims of various types. In some actions, the claimants seek damages, as well as other relief, which, if granted, would require significant expenditures. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability to the Company and the amount of the loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in its consolidated financial statements. During the year ended December 31, 2023, there have been no material changes to any outstanding litigation, nor is the Company a party to any significant new litigation. 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, 2023, the satisfaction and timing of the contingent payments is uncertain and not reasonably estimable.

Collaborations and Other Arrang

Collaborations and Other Arrangements	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations and Other Arrangements	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, 2023, the Company’s accounts receivable were related to its collaborations with Regeneron, SparingVision, AvenCell and Kyverna and the Company’s contract liabilities were related to its collaborations with Regeneron and SparingVision. As of December 31, 2022, the Company’s accounts receivable were related to its collaborations with Regeneron, AvenCell, SparingVision and ONK and the Company’s contract liabilities were related to its collaborations with Regeneron, AvenCell, SparingVision and Kyverna. The following table presents changes in the Company’s accounts receivable and contract liabilities (in thousands): Balance at Additions Deductions Balance at End Year Ended December 31, 2023 Accounts receivable $ 3,768 $ 51,421 $ ( 18,733 ) $ 36,456 Contract liabilities - deferred revenue $ 63,771 $ 40,312 $ ( 43,090 ) $ 60,993 Balance at Additions Deductions Balance at End Year Ended December 31, 2022 Accounts receivable $ 2,031 $ 12,453 $ ( 10,716 ) $ 3,768 Contract liabilities - deferred revenue $ 127,235 $ - $ ( 63,464 ) $ 63,771 T he 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 Year Ended Amounts included in the contract liability at the beginning of the period $ 23,462 $ 52,060 $ 22,544 Costs to obtain and fulfill a contract The Company has not incurred significant 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 (as amended from time to time, 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”). In connection with the 2016 Regeneron Agreement, the Company received a nonrefundable upfront payment of $ 75.0 million. In addition, on Regeneron programs that are not subject to Co/Co agreements, the Company may be eligible to earn, on a per-licensed target basis, (i) up to $ 25.0 million in development milestones, including for the dosing of the first patient in each of Phase I, Phase II and Phase III clinical trials, (ii) up to $ 110.0 million in regulatory milestones, including for the acceptance of a regulatory filing in the U.S., and for obtaining regulatory approval in the U.S. and in certain other identified countries, and (iii) up to $ 185.0 million in sales-based milestone payments. The Company is also eligible to earn royalties ranging from the high-single digits to low teens, in each case, on a per-product basis, which royalties are potentially subject to various reductions and offsets and incorporate the Company’s existing low- to mid-single-digit royalty obligations under a license agreement with Caribou. In connection with the 2016 Regeneron Agreement, Regeneron purchased $ 50.0 million of the Company’s common stock in a private placement under a stock purchase agreement concurrent with the Company’s IPO. In May 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 technology collaboration was extended until April 2024, at which point Regeneron would have an option to renew for an additional two years. The 2020 Regeneron Amendment also granted 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. As part of the consideration for the 2020 Regeneron Amendment, Regeneron paid the Company an upfront payment of $ 70.0 million, which included the $ 25.0 million fee to extend the Technology Collaboration Term, as defined in the 2016 Regeneron Agreement, to April 2024 . The potential future milestones and royalties remain unchanged from the 2016 Regeneron Agreement. In addition, on May 30, 2020 , the Company and Regeneron entered into the 2020 Stock Purchase Agreement. Under the 2020 Stock Purchase Agreement, 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 (the “Equity Transaction”), 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 of the Equity Transaction. 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. In October 2023, Regeneron notified the Company that it was exercising its one-time option to extend the Technology Collaboration Term for an additional two years (the “2024 Technology Collaboration Extension”) , until April 2026 , in exchange for a nonrefundable payment of $ 30.0 million due in April 2024. 2024 Technology Collaboration Extension: Accounting Analysis. The 2024 Technology Collaboration Extension was accounted for as a contract modification. The promised goods and services under the 2024 Technology Collaboration Extension are not distinct from the combined performance obligations identified in the 2020 Regeneron Amendment, which was only partially satisfied at the date of option exercise. A cumulative catch-up adjustment was recorded during the fourth quarter of 2023 resulting in a charge of $ 10.3 million against revenue previously recognized. The transaction price of the 2024 Technology Collaboration Extension was determined to be $ 51.7 million, which is comprised of the $ 11.4 million remaining consideration under the 2020 Regeneron Amendment as of the modification date, the $ 30.0 million extension fee and the $ 10.3 million cumulative catch-up adjustment. The $ 51.7 million transaction price was allocated to the performance obligations including the licenses to targets and associated research activities and evaluation plans and the combined performance obligation including the technology collaboration and associated research activities, on a relative standalone selling price basis. As a result of this evaluation, the Company allocated $ 48.3 million to the combined performance obligation including the licenses to targets and associated research activities and evaluation plans and $ 3.4 million to the combined performance obligation including the technology collaboration and associated research activities, which are being recognized using a time elapsed inputs method from the October 2023 extension date through April 2026, the remaining period of the collaboration. ATTR and Hemophilia Co/Co Agreements: Accounting Analysis. The Company concluded that the ATTR Co/Co and Hemophilia Co/Co agreements meet 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 ATTR Co/Co and the Hemophilia Co/Co agreements 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. In September 2023, Regeneron and Intellia further expanded the research collaboration (the “2023 Regeneron Amendment”) to develop additional in vivo CRISPR-based gene editing therapies focused on neurological and muscular diseases. The collaboration will leverage Intellia’s proprietary Nme2 CRISPR/Cas9 genome editing systems adapted for viral vector delivery and designed to precisely modify a target gene and Regeneron’s proprietary antibody-targeted adeno-associated virus vectors and delivery systems. Under the terms of the expanded research collaboration, the companies will initially research two in vivo non-liver targets. Intellia will lead the design of the editing methodology and Regeneron will lead the design of the targeted viral vector delivery approach and the parties will share research costs equally. Each party will have the opportunity to lead potential development and commercialization for one product candidate, and the party that is not leading development and commercialization will have the option to enter into a co-development and co-promotion agreement for the target. 2023 Regeneron Amendment: Accounting Analysis . The Company concluded that the accounting for the 2023 Regeneron Amendment is within the scope of ASC 606. The Company identified one performance obligation, the transfer of the license and performance of collaborative research and development activities. There is no upfront consideration related to the 2023 Regeneron Amendment. As the 2023 Regeneron Amendment progresses, the Company and Regeneron will share research costs equally. Any cost reimbursements received from Regeneron will be recorded as a component of revenue and any payments made to Regeneron will be recorded as a reduction of revenue. Since December 31, 2022, there have been no material changes to the key terms of the 2016 Regeneron Agreement, ATTR Co/Co or Hemophilia Co/Co (the “Regeneron Agreements”), other than as described above. For further information on the terms and conditions of these agreements, see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2022. Revenue Recognition: Collaboration Revenue. The Company recognized $ 21.0 million, $ 24.1 million and $ 25.7 million of collaboration revenue in the years ended December 31, 2023, 2022 and 2021, respectively, in the consolidated statements of operations and comprehensive loss. This includes $ 19.6 million, $ 11.9 million, and $ 5.9 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 approximately $ 10.7 million in the year ended December 31, 2023, $ 10.4 million in the year ended December 31, 2022 and $ 2.7 million in the year ended December 31, 2021. As of December 31, 2023, there was approximately $ 47.1 million of the aggregate transaction price remaining to be recognized that will be recognized through April 2026, the remaining period of the collaboration. As of December 31, 2023 and 2022, the Company had accounts receivable of $ 35.7 million and $ 3.2 million, respectively, and deferred revenue of $ 47.1 million and $ 28.8 million, respectively, related to the Regeneron Agreements. AvenCell Therapeutics, Inc. In July 2021, the Company entered into two agreements with AvenCell, a privately held chimeric antigen receptor T (“CAR-T”) cell therapy company formed on that date in a joint venture between the Company, Cellex Cell Professionals GmbH (“Cellex”) and funds managed by Blackstone Life Sciences Advisors L.L.C. (“BXLS”): (i) a license and collaboration agreement (the “AvenCell 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. In November 2022, the Company decided to re-prioritize its ex vivo programs and terminated the AvenCell Co/Co, effectively turning over control of the program to AvenCell. The Company’s obligations under the terminated agreement were completed in the second quarter of 2023. Since December 31, 2022, there have been no other material changes to the key terms of the AvenCell LCA and AvenCell Co/Co agreements. Revenue Recognition – Collaboration Revenue. The Company recognized $ 13.2 million, $ 22.8 million and $ 5.9 million in revenue related to the AvenCell LCA for the years ended December 31, 2023, 2022 and 2021, respectively, after eliminating $ 6.6 million, $ 11.4 million and $ 2.9 million in intra-entity profits during those respective periods, 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, this revenue is indefinitely deferred and excluded from the results of operations of the Company. The Company also recognized $ 0.2 million and $ 0.3 million related to materials shipped in accordance with the AvenCell LCA in the years ended December 31, 2023 and 2022, respectively. The Company recognized $ 0.6 million and $ 2.0 million in contra-revenue in the years ended December 31, 2023 and 2022, respectively, related to the AvenCell Co/Co agreement. The Company recognized $ 0.2 million in revenues related to the AvenCell Co/Co agreement for the year ended December 31, 2021. As of December 31, 2023, there was no remaining transaction price of the AvenCell LCA to be recognized. The Company had $ 0.2 million in accounts receivable and no deferred revenue related to the AvenCell agreements as of December 31, 2023. As of December 31, 2022 , the Company had $ 0.3 million in accounts receivable and deferred revenue of $ 19.9 million related to the AvenCell agreements. 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. Since December 31, 2022, there have been no material changes to the key terms of the SparingVision LCA. For further information on the terms and conditions of these agreements, see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2022. Revenue Recognition: Collaboration Revenue. The Company recognized $ 1.8 million and $ 0.2 million in revenue related to the SparingVision LCA for the years ended December 31, 2023 and 2022, respectively. The Company did no t recognize collaboration revenue in the year ended December 31, 2021 related to the SparingVision LCA. As of December 31, 2023 and 2022, the Company had $ 0.5 million and $ 0.1 million in accounts receivable, respectively, related to the SparingVision LCA. As of December 31, 2023 and 2022, the Company had deferred revenue of $ 13.9 million and $ 14.7 million related to the SparingVision LCA, respectively, which is expected to be recognized over a six to nine year period from the signing of the agreement. 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. Since December 31, 2022, there have been no material changes to the key terms of the Kyverna LCA. For further information on the terms and conditions of this agreement, see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2022. Revenue Recognition: Collaboration Revenue. The Company had recognized revenue from the Kyverna LCA in full as of March 31, 2023, including $ 0.4 million and $ 6.6 million in revenue for the years ended December 31, 2023 and 2022, respectively . The Company recognized approximately $ 0.1 million in revenue in the year ended December 31, 2023 related to materials shipped to Kyverna. The Company did no t recognize any revenue for the year ended December 31, 2021 re lated to the Kyverna LCA. As of December 31, 2023, the Company had $ 0.1 million in accounts receivable related to the Kyverna LCA. As of December 31, 2022, the Company did no t have accounts receivable related to the Kyverna LCA. As of December 31, 2023, the Company did no t have deferred revenue related to the Kyverna LCA. As of December 31, 2022 the Company had deferred revenue of $ 0.4 million related to the Kyverna LCA. ONK Therapeutics, Ltd. On February 12, 2022 the Company entered into a license, collaboration and option agreement (the “ONK LCA”) with ONK, an innovative company dedicated to developing optimally engineered natural killer (“NK”) cell therapies to cure patients with cancer. Since December 31, 2022, there have been no material changes to the key terms of the ONK LCA. Revenue Recognition: Collaboration Revenue. The Company recognized $ 0.2 million and $ 0.1 million in revenue for the years ended December 31, 2023 and 2022, respectively, related to materials shipped in accordance with the ONK LCA. As of December 31, 2023, the Company did no t have accounts receivable related to the ONK LCA. As of December 31, 2022, the Company had $ 0.1 million in accounts receivable related to the ONK LCA.

Equity-Method Investment and Ot

Equity-Method Investment and Other Investments	12 Months Ended
	Dec. 31, 2023
Equity Method Investments and Joint Ventures [Abstract]
Equity-Method Investment and Other Investments	10. Equity-Method Investment and Other Investments AvenCell Therapeutics, Inc. In July 2021, 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. 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 records its share of losses from AvenCell on a quarterly basis on a one-quarter lag. The Company evaluates material events occurring during the quarter lag to determine whether the effects of any such events should be disclosed in the financial statements. The Company’s share of AvenCell ’s losses were $ 14.1 million, $ 14.3 million and $ 1.8 million for the years ended December 31, 2023, 2022 and 2021, respectively, and are reflected in its operating results and comprehensive loss. The Company eliminated intra-entity profit of $ 6.6 million, $ 11.4 million and $ 2.9 million for the years ended December 31, 2023, 2022 and 2021, respectively (see Note 9). The carrying value of the Company ’ s investment in AvenCell was $ 11.8 million and $ 32.5 million as of December 31, 2023 and 2022, respectively. In February 2024, AvenCell notified the Company that it is evaluating the valuation of its intangible assets for potential impairment which may result in the reduction of the Company’s equity method investment. AvenCell’s financial statements for the three months ended December 31, 2023, had not been finalized at the time the Company’s financial statements were issued. At December 31, 2023, the maximum exposure to loss is limited to the Company’s equity investment in the joint venture as adjusted for intra-entity profits that have been deferred to date. 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. The Company recorded the initial investment in SparingVision of $ 14.8 million in “Investments and other assets” on its consolidated balance sheet. There have been no changes in the valuation of the investment in SparingVision as of December 31, 2023. 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”). As of December 31, 2023, t he Company accounted for the Kyverna investments using the measurement alternative as Kyverna was a private company with no readily observable transaction price. The Company recorded the initial investment in Kyverna of $ 10.0 million in “Investments and other assets” on its condensed consolidated balance sheet. There have been no changes in the valuation of the investment in Kyverna as of December 31, 2023. In February 2024, Kyverna announced the completion of its IPO and its common stock began trading on the Nasdaq Global Select Market under the ticker symbol “KYTX” .

Rewrite Acquisition

Rewrite Acquisition	12 Months Ended
	Dec. 31, 2023
Business Combinations [Abstract]
Rewrite Acquisition	In February 2022, the Company entered into an Agreement and Plan of Merger by and among the Company, Rewrite, RW Acquisition Corp. and Shareholder Representative Services, LLC as Securityholder representative (the “Rewrite Merger Agreement”). Under the Rewrite Merger Agreement, the Company paid Company Securityholders (as defined in the Rewrite Merger Agreement) (the “Rewrite Holders”) upfront consideration in an aggregate amount of $ 45.0 million, excluding customary purchase price adjustments and closing costs, payable in cash. Pursuant to the Rewrite Merger Agreement, the Company acquired all of the issued and outstanding shares of Rewrite. The Rewrite transaction resulted in the acquisition of certain know-how and IP assets related to Rewrite’s proprietary DNA writing technology. The Company’s management determined that the acquired assets do not meet the definition of a business pursuant to ASC 805, Business Combinations , as substantially all of the fair value of the acquired assets is concentrated into one identifiable asset, the DNA writing technology. As of the date of closing of the transactions contemplated by the Rewrite Merger Agreement (the “Rewrite Merger Agreement Date”), the asset acquired had no alternative future use and had not reached a stage of technological feasibility. As a result, all payment obligations were recorded as research and development expense in the condensed consolidated statements of operations and other comprehensive loss in the amount of $ 56.0 million. The total transaction price was allocated to the assets acquired and liabilities assumed on a relative fair value basis. In addition, the Rewrite Holders are eligible to receive up to an additional $ 155.0 million, including $ 55.0 million upon the achievement of pre-specified research milestones and $ 100.0 million upon the achievement of a regulatory approval milestone, payable through a mixture of $ 130.0 million in cash and $ 25.0 million in a combination of cash and the Company’s common stock which would be valued using the volume-weighted average price of the Company’s Common Stock 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. In September 2022, Rewrite merged into Intellia, with Intellia the surviving entity. In January 2023, the $ 25.0 million research milestone noted above was achieved and, in February 2023, the Company paid the Rewrite Holders $ 0.9 million in cash and issued 567,045 shares of Intellia common stock in order to fulfill its obligation under the Rewrite Merger Agreement. The cash obligation was recorded as research and development expense in the consolidated statement of operations and other comprehensive loss in the first quarter of 2023. The Company had determined that the research milestone settled in the Company’s common stock would be classified as a contingent consideration liability under ASC 480 and, therefore, the Company initially recorded a liability for this milestone payment as of the Rewrite Merger Agreement Date at its original fair value of $ 10.5 million. The contingent consideration liability was remeasured at fair value each financial reporting period, with the resulting impact reflected in the Company’s consolidated statements of operations and other comprehensive loss, presented within other income (expense). The remaining milestones to be settled in cash would be recorded when the contingency is resolved and the consideration is paid or becomes payable. The transaction price on the Rewrite Merger Agreement Date was determined and allocated as follows (in thousands): Transaction Price Upfront cash consideration $ 43,730 Research contingent consideration liabilities 10,541 Transaction costs 1,838 Total transaction price $ 56,109 Transaction Price Allocated In-process research and development $ 55,990 Cash acquired 287 Other current assets acquired 153 Other liabilities assumed ( 321 ) Total transaction price $ 56,109

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	12. Leases Property Leases - Commenced The Company leases approximately 230,000 square feet of real estate, including laboratory and office space in Cambridge, Massachusetts, and the surrounding areas. The Company’s leases have remaining terms ranging from one to approximately nine years. Certain leases include options to renew, exercised at the Company’s sole discretion, with varying renewal terms that can extend the lease term for an additional three to five years. All of the Company’s leases qualify as operating leases. In January 2023, the Company executed a sublease for approximately 13,000 square feet of space of laboratory and office space in Cambridge, Massachusetts for a term of approximately three years. The sublease agreement grants an option to renew the term for one additional year. Property Leases – Not Yet Commenced In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of office, general laboratory and planned good manufacturing practice (“GMP”) manufacturing space at 840 Winter Street in Waltham , Massachusetts (the “840 Winter Lease”). The Company has committed to making at least $ 146.0 million in rental payments over a lease term of 144 months estimated to begin in the second half of 2024. The Company has the option to extend the 840 Winter Lease for two five-year terms. In June 2023, the Company executed an amendment to the 840 Winter Lease, which outlines the Company’s and the landlord’s responsibilities regarding the construction of the leased space. The Company will be responsible for the oversight of the construction of the tenant improvements, which will be primarily funded by a tenant improvement allowance of up to $ 400 per rentable square foot, a portion of which would be repaid over the term of the lease with interest. The Company will also be responsible for certain future construction costs to the extent that they exceed the tenant improvement allowance. The Company anticipates a phased move-in process during the second half of 2024. As of December 31, 2023, the Company had not taken control of the premises and therefore there are no right of use assets or liabilities recorded related to the 840 Winter Lease under ASC 842, Leases (Topic 842) ( “ ASC 842 ” ). 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 costs. The following table contains a summary of the lease costs recognized under ASC 842 and other information pertaining to the Company’s operating leases: Year Ended December 31, 2023 2022 (In thousands) Lease cost Operating lease cost $ 27,849 $ 18,031 Variable lease cost 6,991 4,443 Sublease income ( 1,439 ) - Net lease cost $ 33,401 $ 22,474 Year Ended December 31, 2023 2022 (In thousands) Other information Operating cash flows used for operating leases $ 25,456 $ 14,656 Operating lease liabilities arising from obtaining right-of-use assets 1,311 67,053 As Of December 31, 2023 2022 Lease term and discount rate Weighted average remaining lease term 6.2 years 6.9 years Weighted average discount rate 7.37 % 7.20 % 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, 2023: Future Operating Lease Payments Year Ending December 31, (in thousands) 2024 $ 26,395 2025 25,933 2026 25,110 2027 17,548 2028 12,300 Thereafter 39,260 Total lease payments $ 146,546 Less: imputed interest ( 31,200 ) Total operating lease liabilities at December 31, 2023 $ 115,346

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	13. Stock-Based Compensation Stock-based compensation expense is classified in the consolidated statements of operations and comprehensive loss as follows: Year Ended December 31, 2023 2022 2021 (In thousands) Research and development $ 82,211 $ 56,279 $ 26,712 General and administrative 51,839 35,121 20,297 Total $ 134,050 $ 91,400 $ 47,009 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. The Company maintains a retirement policy for equity awards granted to all employees (the “Retirement Policy”), which applies to all equity awards granted after July 1, 2022 to employees who meet certain retirement eligibility criteria set forth in the Retirement Policy (the “Retirees”). Pursuant to the terms of the Retirement Policy, upon a Retiree’s eligible retirement: (i) all stock options held by the Retiree will continue to vest following the Retiree’s retirement date according to the original vesting schedule of the option until fully vested and all vested stock options held by such Retiree will remain exercisable until the earlier of the five-year anniversary of the Retiree’s retirement date or the original expiration date of the option, (ii) all unvested time-based RSUs held by the Retiree will vest in full on the Retiree’s retirement date and (iii) all unvested performance-based awards held by the Retiree will remain outstanding following the Retiree’s retirement date and the Retiree will remain eligible to earn a pro-rated portion of such performance-based awards at the end of the performance period based on actual performance during the performance period. As of December 31, 2023, there were 3,875,539 shares available for future issuance under the 2015 Plan. The number of shares reserved for issuance under the 2015 Plan will be cumulatively increased on each January 1 st by four percent of the number of shares of stock issued and outstanding on the immediately preceding December 31 st or such lesser number of shares of stock as determined by the board of directors. Restricted Stock Units The following table summarizes the Company’s RSU activity for the year ended December 31, 2023: Number of Weighted Unvested restricted stock units as of December 31, 2022 1,941,379 $ 70.70 Granted 3,047,544 41.30 Vested ( 677,055 ) 68.04 Cancelled ( 270,115 ) 49.41 Unvested restricted stock units as of December 31, 2023 4,041,753 $ 50.40 In March 2023, the Company granted 2,195,135 RSUs with a service condition to employees as part of their annual grant, which have the potential to vest over a period of three years . The weighted average grant date fair value of these RSUs was $ 40.75 and the vesting start date for these RSUs was January 1, 2023. Also in March 2023, 181,743 market-based RSUs were granted to senior executives as part of their annual grant. These RSUs have the potential to vest after a period of three years , with a vesting start date of January 1, 2023, and the number of shares to be delivered will depend on the Company’s Total Shareholder Return (“TSR”), a market condition, over that period relative to a defined group of biotechnology companies. The grant date fair value for these RSUs, calculated using a Monte Carlo valuation model, was $ 68.55 . The following assumptions were used to determine the grant date fair value: risk free interest rate: 4.60 %; expected dividend yield: 0.0 %; expected volatility: 84.34 %; expected term (in years): 2.84 . In March 2022, the Company granted 794,424 RSUs with a service condition to employees as part of their annual grant, which have the potential to vest over a period of three years . The weighted average grant date fair value of these RSUs was $ 79.85 and the vesting start date for these RSUs was January 1, 2022. Also in March 2022, 55,144 RSUs were granted to senior executives as part of their annual grant. These RSUs have the potential to vest after a period of 3 years , with a vesting start date of January 1, 2022, and the number of shares to be delivered will depend on the Company’s TSR, a market condition, over that period relative to a defined group of biotechnology companies. The grant date fair value for these RSUs, calculated using a Monte Carlo valuation model, was $ 126.49 . The following assumptions were used to determine the grant date fair value: risk free interest rate: 1.44 %; expected dividend yield: 0.0 %; expected volatility: 82.53 %; expected term (in years): 2.84 . The Company also granted 66,296 performance-based RSUs in March 2022 to certain non-executive employees that would vest upon obtaining certain scientific milestones. There were two separate tranches, each attached to a different set of milestones. The milestone related to the first tranche, made up of 21,878 RSUs, was achieved in the first quarter of 2023 and these RSUs vested. The remaining performance milestones were considered not probable of achievement as of December 31, 2023 and, therefore, no related stock-based compensation was recorded during the period then ending for those RSUs. RSUs granted under the 2015 Plan in 2023 generally vest as to one-third on the first anniversary of the original vesting date, with the balance vesting annually over the remaining two years. The weighted-average grant date fair value of RSUs granted for the years ended December 31, 2023, 2022 and 2021 was $ 41.30 , $ 70.90 and $ 73.81 , respectively. The total fair value of RSUs vested (measured on the date of vesting) for the years ended December 31, 2023, 2022 and 2021 was $ 24.9 million, $ 10.4 million and $ 14.1 million, respectively. As of December 31, 2023, there was $ 125.2 million of unrecognized stock-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 1.7 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 $ 28.92 , $ 57.23 and $ 54.09 per option for options granted during the years ended December 31, 2023, 2022 and 2021, respectively. Weighted average assumptions used to apply this pricing model were as follows: Year Ended December 31, 2023 2022 2021 Risk-free interest rate 4.4 % 1.9 % 1.0 % Expected life of options 6.0 years 5.9 years 6.0 years Expected volatility of underlying stock 78.7 % 76.2 % 72.9 % 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 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. Expected Volatility. Beginning in the first quarter of 2023, expected volatility is estimated based on actual movements in the Company’s stock price over the most recent historical periods, over the expected term of their stock option grants. Prior to 2023, 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 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. Stock options granted under the 2015 Plan in 2023 generally vest as to one-third on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining two years, unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years. 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, 2023: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding at December 31, 2022 5,471,675 $ 49.86 Granted 569,821 41.00 Exercised ( 385,130 ) 17.13 Forfeited ( 197,367 ) 73.90 Outstanding at December 31, 2023 5,458,999 $ 50.38 6.65 $ 35,922 Exercisable at December 31, 2023 4,017,227 $ 43.63 6.14 $ 34,790 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, 2023, 2022 and 2021 was $ 7.6 million, $ 42.8 million, and $ 262.0 million, respectively. As of December 31, 2023, there was $ 56.1 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 1.4 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, 2023, there were 1,077,487 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, 2023, 2022, and 2021, the Company issued 142,079 , 77,618 , and 30,897 shares of common stock under the 2016 Plan, respectively. The weighted-average purchase prices of shares issued under the 2016 Plan were $ 27.65 , $ 34.15 and $ 65.51 per share for the years ended December 31, 2023, 2022, and 2021, 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, 2023 2022 2021 Risk-free interest rate 4.7 %- 5.53 % 0.22 %- 2.52 % 0.05 %- 0.09 % Expected term (in years) 0.5 years 0.5 years 0.5 years Expected volatility of underlying stock 60.4 %- 69.2 % 63.6 %- 95.3 % 77.5 %- 109.2 % Expected dividend yield 0.0 % 0.0 % 0.0 %

Loss Per Share

Loss Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Loss Per Share	14. Loss Per Share Basic and diluted loss per share was calculated as follows: Year Ended December 31, 2023 2022 2021 (In thousands) Net loss $ ( 481,192 ) $ ( 474,186 ) $ ( 267,892 ) Weighted average shares outstanding, basic 88,770 76,972 70,894 Net loss per share, basic and diluted $ ( 5.42 ) $ ( 6.16 ) $ ( 3.78 ) The following common stock equivalents were excluded from the calculation of diluted loss per share because their inclusion would have been anti-dilutive: Year Ended December 31, 2023 2022 2021 (In thousands) Unvested restricted stock units 4,042 1,941 453 Stock options 5,459 5,472 6,305 9,501 7,413 6,758

Stockholders_ Equity

Stockholders’ Equity	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Stockholders’ Equity	15. Stockholders’ Equity At-the-Market Offering Programs 2019 Sale Agreement In August 2019, the Company entered into an Open Market Sale Agreement (the “2019 Sale Agreement”) with Jefferies LLC (“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 cash commissions of 3.0 % of the gross proceeds of sales of common stock under the 2019 Sale Agreement. Under the 2019 Sale Agreement, the Company issued 3,778,889 shares of its common stock. During the first quarter of 2022, the Company issued 579,788 shares of its common stock, in a series of sales, at an average price of $ 69.43 per share, in accordance with the 2019 Sale Agreement for aggregate net proceeds of $ 38.9 million, after payment of cash commissions and legal, accounting and other fees in connection with the sales. The 2019 Sale Agreement expired in the third quarter of 2022. 2022 Sale Agreement In March 2022, the Company entered into an Open Market Sale Agreement (the “2022 Sale Agreement”) with Jefferies, under which Jefferies is able to offer and sell, from time to time in “at-the-market” offerings, shares of the Company’s common stock having aggregate gross proceeds of up to $ 400.0 million. The Company agreed to pay cash commissions of 3.0 % of the gross proceeds of sales of common stock under the 2022 Sale Agreement. Through December 31, 2023, the Company issued 7,518,163 shares of its common stock under the 2022 Sale Agreement. During the year ended December 31, 2023, the Company issued 4,122,824 shares of its common stock, in a series of sales, at an average price of $ 30.57 per share, in accordance with the 2022 Sale Agreement for aggregate net proceeds of $ 121.9 million, after payment of cash commissions and legal, accounting and other fees in connection with the sales. During the year ended December 31, 2022, the Company issued 3,395,339 shares of its common stock, in a series of sales, at an average price of $ 57.43 per share, in accordance with the 2022 Sale Agreement for aggregate net proceeds of $ 189.0 million, after payment of cash commissions and legal, accounting and other fees in connection with the sales. As of December 31, 2023, $ 2.1 million of these proceeds are included in “Prepaid expenses and other current assets” on the Company’s consolidated balance sheet, representing offerings with trade dates in December 2023 that were settled in January 2024. As of December 31, 2023, $ 79.0 million in shares of common stock remain eligible for sale under the 2022 Sale Agreement. Follow-on Offerings 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. In November 2022, the Company entered into an underwriting agreement related to a public offering of 6,550,219 shares of its common stock, par value $ 0.0001 per share, at a public offering price of $ 45.80 per share. In addition, the Company granted the underwriter an option exercisable for 30 days from the date of the agreement to purchase, at the public offering price less any underwriting discounts and commissions, up to an additional 982,532 shares. The offering closed on December 2, 2022 and the Company received net proceeds of $ 337.9 million, including the exercise in full of the underwriters' option to purchase additional shares, after deducting the underwriting discount, commissions and offering expenses. Approval of Additional Authorized Shares In June 2023, the Company filed a Certificate of Amendment to the Company’s Second Amended and Restated Certificate of Incorporation to increase the number of authorized shares of common stock from 120,000,000 to 240,000,000 . The increase in the number of authorized shares was approved by the holders of a majority of the outstanding shares of the Company’s common stock at its Annual Meeting of Stockholders held on June 14, 2023.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions	16. 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, 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. The Company recognized $ 13.2 million, $ 22.8 million and $ 5.9 million in revenue related to the AvenCell LCA for the years ended December 31, 2023, 2022 and 2021, respectively, after eliminating $ 6.6 million, $ 11.4 million and $ 2.9 million in intra-entity profits during those respective periods. The elimination of intra-entity profits results in the deferral of revenue that will be recognized if and when AvenCell commercializes a product with the Company ’ s license or abandons the related project. Until such time, this revenue is indefinitely deferred and excluded from the results of operations of the Company. The Company also recognized $ 0.2 million and $ 0.3 million related to materials shipped in accordance with the AvenCell LCA in the years ended December 31, 2023 and 2022, respectively. The Company and AvenCell were also parties to the AvenCell Co/Co, under which the Company would co-develop and co-commercialize allogeneic universal CAR-T cell products for an immuno-oncology indication. This agreement was terminated by the Company, and all obligations under the terminated agreement were completed in the second quarter of 2023. The Company recognized $ 0.6 million and $ 2.0 million in contra-revenue in the years ended December 31, 2023 and 2022, respectively, related to the AvenCell Co/Co agreement. The Company recognized $ 0.2 million in revenues related to the AvenCell Co/Co agreement for the year ended December 31, 2021. As of December 31, 2023 , there was no remaining transaction price of the AvenCell LCA to be recognized.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
401(k) Plan	17. 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 $ 3.3 million, $ 2.7 million and $ 1.6 million for the years ended December 31, 2023, 2022 and 2021, respectively.

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Event	18. Subsequent Event On February 15, 2024, the Company announced a strategic collaboration with ReCode Therapeutics, Inc. (“ReCode”), a clinical-stage genetic medicines company, to develop novel genomic medicines for the treatment of cystic fibrosis (“CF”). CF is a genetic disease caused by mutations in the CFTR gene, leading to the accumulation of thick mucus in the lungs, digestive systems and other organs. CF can result in life-threatening infections, respiratory failure and other serious complications. The collaboration will leverage the Company’s proprietary CRISPR-based gene editing platform, including its DNA writing technology, and ReCode’s proprietary Selective Organ Targeting (“SORT” ) lipid nanoparticle delivery platform to precisely correct one or more CF disease-causing gene mutations. As part of the agreement, the companies will focus initial research efforts on therapeutic approaches that address CF for patients who have limited or no treatment options available, with the opportunity to expand the scope of the collaboration in later phases. The Company will be responsible for the design of the editing strategy and research-grade components for the investigational therapies. ReCode will lead the subsequent preclinical and clinical development. ReCode will also lead worldwide commercialization for certain programs arising from the collaboration. The Company will be eligible to receive pre-specified development and commercial milestone payments, as well as royalties on potential sales. The Company may also exercise an option to lead commercialization in the U.S. for certain programs.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
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. In February 2022, the Company entered into an agreement to acquire Rewrite Therapeutics, Inc., a Delaware corporation (“Rewrite”). On the effective date of the agreement, Rewrite became a wholly owned subsidiary of the Company. In September 2022, Rewrite merged into Intellia, with Intellia the surviving entity.
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 and determination of impairment of equity and fair value method investments, contingent consideration and stock-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 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, restricted cash equivalents, marketable securities, accounts receivable, non-marketable securities, accounts payable and accrued expenses. Certain of the Company’s financial assets, including cash equivalents, restricted 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. Investments in non-marketable securities are accounted for using the measurement alternative at cost minus impairment, adjusted for changes in observable prices. 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, 2023, cash equivalents consisted of interest-bearing money market accounts, U.S. Treasury bills and other government securities. As of December 31, 2022, cash equivalents consisted of interest-bearing money market accounts and reverse purchase agreements.
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 certain of its leases. As of December 31, 2023, these restricted cash equivalents amounted to $ 13.6 million. As of December 31, 2022, these restricted cash equivalents amounted to $ 12.0 million. The letters of credit are required to be maintained throughout the term of the leases; in some cases, the Company is able to reduce the amounts held over time. These restricted cash equivalents are long-term in nature and are included in “Investments and other assets” in the Company’s consolidated balance sheets.
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.
Asset acquisitions	Asset Acquisitions At the time of acquisition, the Company determines if a transaction should be accounted for as a business combination or acquisition of assets. The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs, and the consideration is allocated to the items acquired based on a relative fair value methodology. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire in-process research and development with no alternative future use is charged to research and development expense at the acquisition date.
Non-Marketable Equity Securities	Non-Marketable Equity Securities The Company periodically 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 there are any indicators of impairment, and if so determines the fair value of the investment and compares to the recorded balance, to determine if there is an impairment, 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, restricted 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, 2023, the Company’s accounts receivable were related to its collaborations with Regeneron Pharmaceuticals, Inc. (“Regeneron”), SparingVision SAS (“SparingVision”), AvenCell Therapeutics, Inc. (“AvenCell”), and Kyverna Therapeutics, Inc. (“Kyverna”). As of December 31, 2022, the Company’s accounts receivable were related to its collaborations with Regeneron, AvenCell, SparingVision and ONK Therapeutics, Ltd. (“ONK”) .
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 Shorter of useful life or remaining lease term 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.
Contingent Consideration	Contingent Consideration The Company accounts for contingent consideration identified in an asset acquisition, that is payable in cash and does not meet the definition of a derivative under Accounting Standard Codification (“ASC”) 815, Derivatives and Hedging , when the contingency is resolved and the consideration is paid or becomes payable. The Company accounts for contingent consideration identified in an asset acquisition that is settled in shares of common stock under ASC 480, Distinguishing Liabilities from Equity (“ASC 480”). The contingent consideration liability will be recorded at fair value at the end of each reporting period with changes in estimated fair values recorded in other (expense) income in the consolidated statements of operations and comprehensive loss.
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 “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, 2023 or 2022 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, 2023, the Company’s revenue recognized is solely 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 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 costs consist of expenses incurred in performing research and development activities, such as salaries, stock-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.
Stock-Based Compensation	Stock-Based Compensation The Company’s stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as an expense over the requisite service period. The fair value of stock option grants is estimated using the Black-Scholes option pricing model. Use of the valuation model requires management to make certain assumptions with respect to selected model inputs. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for a term consistent with the expected life of the stock options. Volatility assumptions are calculated based on historical volatility of the Company’s stock. The Company estimates the expected term of options using the simplified method. In addition, an expected dividend yield of zero is used in the option valuation model because the Company does not pay cash dividends and does not expect to pay any cash dividends in the foreseeable future. Forfeitures are recorded as they occur. The fair value of market-based restricted stock units is determined using a Monte Carlo simulation model, which uses multiple input variables to determine the probability of satisfying the market condition requirements. For awards with service conditions only, the Company recognizes stock-based compensation expense on a straight-line basis over the requisite service period. For awards with service and performance-based conditions, the Company recognizes stock-based compensation expense using the graded vesting method over the requisite service period. For awards with market-based conditions, the Company recognizes stock-based compensation expense using the accelerated attribution method over the requisite service period. Estimates of stock-based compensation expense for an award with performance conditions are based on the probable outcome of the performance conditions and the cumulative effect of any changes in the probability outcomes are recorded in the period in which the changes occur. The Company classifies stock-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’s chief executive officer, its chief operating decision maker, manages the Company’ s operations as a single segment for the purpose 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, 2023 and 2022, the Company accounted for its investment in AvenCell under the equity method of accounting and no impairment charges were recognized during the years ended December 31, 2023 or 2022. Refer to Note 10 for further details.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements There were no accounting pronouncements adopted by the Company in 2023. Recent Issued Accounting Pronouncements Not Yet Effective In November 2023, the FASB issued ASU No. 2023-07, “Segment Reporting - Improvements to Reportable Segment Disclosures.” The amendments require disclosure of incremental segment information on an annual and interim basis. The amendments also require companies with a single reportable segment to provide all disclosures required by this amendment and all existing segment disclosures in ASC 280, “Segment Reporting.” The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods beginning after December 15, 2024. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures. In December 2023, the FASB issued ASU No. 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures.” This ASU updates income tax disclosure requirements primarily by requiring specific categories and greater disaggregation within the rate reconciliation and disaggregation of income taxes paid by jurisdiction. This ASU is effective for annual periods beginning after December 15, 2024 and is applicable to the Company’s fiscal year beginning January 1, 2025, with early application permitted. The Company is currently evaluating the impact of adopting this ASU on its consolidated financial statements and disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
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 Shorter of useful life or remaining lease term

Marketable Securities (Tables)

Marketable Securities (Tables)	12 Months Ended
	Dec. 31, 2023
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: December 31, 2023 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 382,260 $ 302 $ ( 254 ) $ 382,308 Financial institution debt securities 246,270 92 ( 243 ) 246,119 Corporate debt securities 97,490 53 ( 135 ) 97,408 Other asset-backed securities 59,453 75 ( 24 ) 59,504 Total $ 785,473 $ 522 $ ( 656 ) $ 785,339 December 31, 2022 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 244,562 $ 62 $ ( 1,938 ) $ 242,686 Financial institution debt securities 380,891 - ( 1,030 ) 379,861 Corporate debt securities 102,059 - ( 509 ) 101,550 Other asset-backed securities 14,703 - ( 346 ) 14,357 Total $ 742,215 $ 62 $ ( 3,823 ) $ 738,454

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liablilities Recognized at Fair Value on Recurring Basis	The Company’s financial assets and liabilities recognized at fair value on a recurring basis consisted of the following: Fair Value as of December 31, 2023 Total Level 1 Level 2 Level 3 Assets (In thousands) Cash equivalents and restricted cash equivalents $ 136,254 $ 136,254 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 382,308 120,556 261,752 - Financial institution debt securities 246,119 - 246,119 - Corporate debt securities 97,408 - 97,408 - Other asset-backed securities 59,504 - 59,504 - Total marketable securities 785,339 120,556 664,783 - Total $ 921,593 $ 256,810 $ 664,783 $ - Fair Value as of December 31, 2022 Total Level 1 Level 2 Level 3 Assets (In thousands) Cash equivalents and restricted cash equivalents $ 534,581 $ 534,581 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 242,686 172,939 69,747 - Financial institution debt securities 379,861 - 379,861 - Corporate debt securities 101,550 - 101,550 - Other asset-backed securities 14,357 - 14,357 - Total marketable securities 738,454 172,939 565,515 - Total $ 1,273,035 $ 707,520 $ 565,515 $ - Liabilities Contingent consideration $ 24,026 $ - $ - $ 24,026
Schedule of Change in Fair Value of the Contingent Consideration Liabilities	The following table reconciles the change in fair value of the contingent consideration liability based on the level 3 inputs listed below for the years ended December 31, 2023 and 2022 (in thousands): Balance at February 2, 2022 (at inception) $ 10,541 Change in fair value 13,485 Balance at December 31, 2022 24,026 Change in fair value 100 Payment of contingent consideration ( 24,126 ) Balance at December 31, 2023 $ - As of inception (February 2, 2022) As of December 31, 2022 Discount rate 7 % 10.1 % Probability of achievement 50 % 100 % Projected year of achievement 2024 2023

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment, net consisted of the following: December 31, 2023 2022 (In thousands) Laboratory equipment $ 63,970 $ 51,911 Office furniture and equipment 2,633 2,633 Computer equipment 982 1,785 Leasehold improvements 3,134 3,066 Computer software 1,902 1,725 Total property and equipment 72,621 61,120 Less: accumulated depreciation and amortization ( 39,861 ) ( 33,199 ) Property and equipment, net $ 32,760 $ 27,921

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: December 31, 2023 2022 (In thousands) Accrued research and development $ 27,411 $ 32,684 Employee compensation and benefits 26,615 21,778 Accrued legal and professional expenses 2,063 1,457 Accrued construction costs 6,891 - Accrued other 4,037 4,957 Total accrued expenses $ 67,017 $ 60,876

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023 2022 2021 Federal statutory income tax rate ( 21.0 )% ( 21.0 )% ( 21.0 )% State income taxes ( 8.6 ) ( 8.3 ) ( 16.6 ) Research and development tax credits ( 6.9 ) ( 5.3 ) ( 8.7 ) Stock-based compensation 1.6 ( 0.1 ) ( 16.8 ) Non-deductible officers' compensation - 0.1 0.2 In-process research and development - 2.5 - Change in valuation allowance 34.9 32.1 62.9 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, 2023 2022 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 258,664 $ 229,375 Research and development credit carryforwards 151,333 101,326 Section 174 capitalized research 150,993 78,873 Operating lease liability 31,183 35,386 Deferred revenue 9,633 13,189 Stock-based compensation 30,408 22,512 Accruals and allowances 6,244 4,968 Prepaid rent 1,190 1,367 Equity investment adjustments 7,580 3,358 Intangibles, including in-process research and development 1,017 930 Capitalized start-up costs 249 296 Gross deferred tax assets 648,494 491,580 Deferred tax asset valuation allowance ( 616,082 ) ( 454,793 ) Total deferred tax assets 32,412 36,787 Deferred tax liabilities: Fixed assets ( 1,221 ) ( 759 ) Operating lease right-of-use assets ( 31,191 ) ( 36,028 ) Total deferred tax liabilities ( 32,412 ) ( 36,787 ) Net deferred tax asset (liability) $ - $ - The Tax Cuts and Jobs Act (“TCJA” ) requires taxpayers to capitalize and amortize, rather than deduct, research and development expenditures under section 174 for tax years beginning after December 31, 2021. These rules became effective for the Company during the year ended December 31, 2022. As a result, the Company has capitalized research and development costs of $ 322.6 million and $ 365.8 million for the years ended December 31, 2022 and December 31, 2023, respectively. The Company will amortize these costs for tax purposes over 5 years if the research and development was performed in the U.S. and over 15 years if the research and development was performed outside the U.S.

Collaborations and Other Arra_2

Collaborations and Other Arrangements (Tables)	12 Months Ended
	Dec. 31, 2023
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 (in thousands): Balance at Additions Deductions Balance at End Year Ended December 31, 2023 Accounts receivable $ 3,768 $ 51,421 $ ( 18,733 ) $ 36,456 Contract liabilities - deferred revenue $ 63,771 $ 40,312 $ ( 43,090 ) $ 60,993 Balance at Additions Deductions Balance at End Year Ended December 31, 2022 Accounts receivable $ 2,031 $ 12,453 $ ( 10,716 ) $ 3,768 Contract liabilities - deferred revenue $ 127,235 $ - $ ( 63,464 ) $ 63,771 T
Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance	he 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 Year Ended Amounts included in the contract liability at the beginning of the period $ 23,462 $ 52,060 $ 22,544

Rewrite Acquisition (Tables)

Rewrite Acquisition (Tables)	12 Months Ended
	Dec. 31, 2023
Business Combinations [Abstract]
Summary of Transaction Price on Rewrite Merger Agreement Date Determined and Allocated	The transaction price on the Rewrite Merger Agreement Date was determined and allocated as follows (in thousands): Transaction Price Upfront cash consideration $ 43,730 Research contingent consideration liabilities 10,541 Transaction costs 1,838 Total transaction price $ 56,109 Transaction Price Allocated In-process research and development $ 55,990 Cash acquired 287 Other current assets acquired 153 Other liabilities assumed ( 321 ) Total transaction price $ 56,109

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
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: Year Ended December 31, 2023 2022 (In thousands) Lease cost Operating lease cost $ 27,849 $ 18,031 Variable lease cost 6,991 4,443 Sublease income ( 1,439 ) - Net lease cost $ 33,401 $ 22,474 Year Ended December 31, 2023 2022 (In thousands) Other information Operating cash flows used for operating leases $ 25,456 $ 14,656 Operating lease liabilities arising from obtaining right-of-use assets 1,311 67,053 As Of December 31, 2023 2022 Lease term and discount rate Weighted average remaining lease term 6.2 years 6.9 years Weighted average discount rate 7.37 % 7.20 %
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, 2023: Future Operating Lease Payments Year Ending December 31, (in thousands) 2024 $ 26,395 2025 25,933 2026 25,110 2027 17,548 2028 12,300 Thereafter 39,260 Total lease payments $ 146,546 Less: imputed interest ( 31,200 ) Total operating lease liabilities at December 31, 2023 $ 115,346

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Schedule of Stock-Based Compensation Expense	Stock-based compensation expense is classified in the consolidated statements of operations and comprehensive loss as follows: Year Ended December 31, 2023 2022 2021 (In thousands) Research and development $ 82,211 $ 56,279 $ 26,712 General and administrative 51,839 35,121 20,297 Total $ 134,050 $ 91,400 $ 47,009
Summary of Restricted Stock Activity	The following table summarizes the Company’s RSU activity for the year ended December 31, 2023: Number of Weighted Unvested restricted stock units as of December 31, 2022 1,941,379 $ 70.70 Granted 3,047,544 41.30 Vested ( 677,055 ) 68.04 Cancelled ( 270,115 ) 49.41 Unvested restricted stock units as of December 31, 2023 4,041,753 $ 50.40
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, 2023 2022 2021 Risk-free interest rate 4.4 % 1.9 % 1.0 % Expected life of options 6.0 years 5.9 years 6.0 years Expected volatility of underlying stock 78.7 % 76.2 % 72.9 % 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, 2023: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding at December 31, 2022 5,471,675 $ 49.86 Granted 569,821 41.00 Exercised ( 385,130 ) 17.13 Forfeited ( 197,367 ) 73.90 Outstanding at December 31, 2023 5,458,999 $ 50.38 6.65 $ 35,922 Exercisable at December 31, 2023 4,017,227 $ 43.63 6.14 $ 34,790
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, 2023 2022 2021 Risk-free interest rate 4.7 %- 5.53 % 0.22 %- 2.52 % 0.05 %- 0.09 % Expected term (in years) 0.5 years 0.5 years 0.5 years Expected volatility of underlying stock 60.4 %- 69.2 % 63.6 %- 95.3 % 77.5 %- 109.2 % Expected dividend yield 0.0 % 0.0 % 0.0 %

Loss Per Share (Tables)

Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
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, 2023 2022 2021 (In thousands) Net loss $ ( 481,192 ) $ ( 474,186 ) $ ( 267,892 ) Weighted average shares outstanding, basic 88,770 76,972 70,894 Net loss per share, basic and diluted $ ( 5.42 ) $ ( 6.16 ) $ ( 3.78 )
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 because their inclusion would have been anti-dilutive: Year Ended December 31, 2023 2022 2021 (In thousands) Unvested restricted stock units 4,042 1,941 453 Stock options 5,459 5,472 6,305 9,501 7,413 6,758

Nature of Operations - Addition

Nature of Operations - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
IPO [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering	$ 2,534.1

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Restricted cash equivalents | $	$ 13,605	$ 11,957	$ 2,080
Restricted Cash Equivalents, Statement of Financial Position [Extensible Enumeration]	Assets, Current	Assets, Current
Percentage of likelihood of realization required to record tax benefit	50%
Number of reportable segment | Segment	1

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)	Dec. 31, 2023
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	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember

Marketable Securities - Summary

Marketable Securities - Summary of Available -for-sale Marketable Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 785,473	$ 742,215
Gross Unrealized Gains	522	62
Gross Unrealized Losses	(656)	(3,823)
Estimated Fair Value	785,339	738,454
U S Treasury And Other Government Backed Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	382,260	244,562
Gross Unrealized Gains	302	62
Gross Unrealized Losses	(254)	(1,938)
Estimated Fair Value	382,308	242,686
Financial Institution Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	246,270	380,891
Gross Unrealized Gains	92	0
Gross Unrealized Losses	(243)	(1,030)
Estimated Fair Value	246,119	379,861
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	97,490	102,059
Gross Unrealized Gains	53	0
Gross Unrealized Losses	(135)	(509)
Estimated Fair Value	97,408	101,550
Other Asset Backed Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	59,453	14,703
Gross Unrealized Gains	75	0
Gross Unrealized Losses	(24)	(346)
Estimated Fair Value	$ 59,504	$ 14,357

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
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 and Liabilities Recognized at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Marketable securities:
Contingent consideration	$ 0	$ 10,541	$ 0
Fair Value on Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and restricted cash equivalents	136,254	534,581
Marketable securities:
Marketable securities	785,339	738,454
Total	921,593	1,273,035
Contingent consideration		24,026
Fair Value on Recurring Basis [Member] | U S Treasury And Other Government Backed Securities [Member]
Marketable securities:
Marketable securities	382,308	242,686
Fair Value on Recurring Basis [Member] | Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	246,119	379,861
Fair Value on Recurring Basis [Member] | Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	97,408	101,550
Fair Value on Recurring Basis [Member] | Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	59,504	14,357
Fair Value on Recurring Basis [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents and restricted cash equivalents	136,254	534,581
Marketable securities:
Marketable securities	120,556	172,939
Total	256,810	707,520
Fair Value on Recurring Basis [Member] | Level 1 [Member] | U S Treasury And Other Government Backed Securities [Member]
Marketable securities:
Marketable securities	120,556	172,939
Fair Value on Recurring Basis [Member] | Level 2 [Member]
Marketable securities:
Marketable securities	664,783	565,515
Total	664,783	565,515
Fair Value on Recurring Basis [Member] | Level 2 [Member] | U S Treasury And Other Government Backed Securities [Member]
Marketable securities:
Marketable securities	261,752	69,747
Fair Value on Recurring Basis [Member] | Level 2 [Member] | Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	246,119	379,861
Fair Value on Recurring Basis [Member] | Level 2 [Member] | Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	97,408	101,550
Fair Value on Recurring Basis [Member] | Level 2 [Member] | Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	$ 59,504	14,357
Fair Value on Recurring Basis [Member] | Level 3 [Member]
Marketable securities:
Contingent consideration		$ 24,026

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Oct. 31, 2021	Jul. 30, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investment	$ 11,765	$ 32,455
Research milestone payments	25,000
Cash [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Research milestone payments	900
AvenCell Member
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investment	11,800	32,500
Investment Owned, Fair Value				$ 62,900
Sparing Vision SAS [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Fair Value	14,800	14,800	$ 14,800
Kyverna [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Owned, Fair Value	$ 10,000	$ 10,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Change in Fair Value of the Contingent Consideration Liabilities (Detail) - USD ($) $ in Thousands		12 Months Ended
	Feb. 02, 2022	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Balance		$ 24,026
Change in fair value		100	$ 13,485
Payment of contingent consideration		(24,126)
Balance	$ 10,541	$ 0	$ 24,026
Discount rate	7%		10.10%
Probability of achievement	50%		100%
Projected year of achievement	2024		2023

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 72,621	$ 61,120
Less: accumulated depreciation and amortization	(39,861)	(33,199)
Property and equipment, net	32,760	27,921
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	63,970	51,911
Office Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	2,633	2,633
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	982	1,785
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	3,134	3,066
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 1,902	$ 1,725

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 8,976	$ 7,572	$ 6,891

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued research and development	$ 27,411	$ 32,684
Employee compensation and benefits	26,615	21,778
Accrued legal and professional expenses	2,063	1,457
Accrued construction costs	6,891	0
Accrued other	4,037	4,957
Total accrued expenses	$ 67,017	$ 60,876

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, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Federal statutory income tax rate	(21.00%)	(21.00%)	(21.00%)
State income taxes	(8.60%)	(8.30%)	(16.60%)
Research and development tax credits	(6.90%)	(5.30%)	(8.70%)
Stock-based compensation	1.60%	(0.10%)	(16.80%)
Non-deductible officers' compensation	0%	0.10%	0.20%
In-process research and development	0%	2.50%	0%
Change in valuation allowance	34.90%	32.10%	62.90%
Effective income tax rate	0%	0%	0%

Income Taxes - Summary of Compa

Income Taxes - Summary of Company's Net Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 258,664	$ 229,375
Research and development credit carryforwards	151,333	101,326
Section 174 capitalized research	150,993	78,873
Operating lease liability	31,183	35,386
Deferred revenue	9,633	13,189
Equity-based compensation	30,408	22,512
Accruals and allowances	6,244	4,968
Prepaid Rent	1,190	1,367
Equity investment adjustments	7,580	3,358
Intangibles, including acquired in-process research and development	1,017	930
Capitalized start-up costs	249	296
Gross deferred tax assets	648,494	491,580
Deferred tax asset valuation allowance	(616,082)	(454,793)
Total deferred tax assets	32,412	36,787
Deferred tax liabilities:
Fixed assets	(1,221)	(759)
Operating lease right-of-use assets	(31,191)	(36,028)
Total deferred tax liabilities	(32,412)	(36,787)
Net deferred tax asset (liability)	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Benefit [Line Items]
Net operating loss carryforwards, federal	$ 954,000	$ 852,100
Capitalized research and development costs	$ 365,800	322,600
Amortization of costs for tax purpose description	The Company will amortize these costs for tax purposes over 5 years if the research and development was performed in the U.S. and over 15 years if the research and development was performed outside the U.S.
Taxable Income available for the period the loss was generated	20 years
Increase in valuation allowance	$ 161,300	150,000	$ 163,900
Research and development and other credit	151,333	101,326
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%
Operating Loss Carryforward Indefinitely [Member]
Income Tax Benefit [Line Items]
Net operating loss carryover, percentage of taxable income	80%
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	$ 36,900
Federal [Member] | Operating Loss Carryforward Indefinitely [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards with no expiration date	917,100
Federal [Member] | Tax Carryforwards Begin to Expire in 2034 [Member]
Income Tax Benefit [Line Items]
Tax credit carryforwards, with expiration date	$ 100,700	63,400
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	$ 64,100	48,000
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	$ 922,800	$ 797,800

Collaborations and Other Arra_3

Collaborations and Other Arrangements - Summary of Changes in Accounts Receivable and Contract Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounts receivable:
Accounts receivable, Balance at Beginning of Period	$ 3,768	$ 2,031
Accounts receivable, Additions	51,421	12,453
Accounts receivable, Deductions	(18,733)	(10,716)
Accounts receivable, Balance at End of Period	36,456	3,768
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	63,771	127,235
Deferred revenue, Additions	40,312	0
Deferred revenue, Deductions	(43,090)	(63,464)
Deferred revenue, Balance at End of Period	$ 60,993	$ 63,771

Collaborations and Other Arra_4

Collaborations and Other Arrangements- Summary of Revenues Recognized Resulting from Changes in Contract Liability Balance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Amounts included in the contract liability at the beginning of the period	$ 23,462	$ 52,060	$ 22,544

Collaborations and Other Arra_5

Collaborations and Other Arrangements - Additional Information (Detail)		1 Months Ended			3 Months Ended	12 Months Ended
	May 30, 2020 USD ($) $ / shares shares	Oct. 31, 2023 USD ($)	May 31, 2020 Product Targetcap	Apr. 30, 2016 USD ($)	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill contract capitalized					$ 0	$ 0
Common stock, par value | $ / shares					$ 0.0001	$ 0.0001	$ 0.0001
Collaboration revenue						$ 36,275,000	$ 52,121,000	$ 33,053,000
Deferred revenue					$ 60,993,000	60,993,000	63,771,000	127,235,000
Revenue						6,600,000	11,400,000	2,900,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Extension fee						30,000,000
Stock purchase agreement date	May 30, 2020
Transaction price						51,700,000
Remaining transaction price transferred at inception of arrangement						11,400,000
Transaction price allocated to combined performance obligation						51,700,000
Aggregate transaction price remaining to be recognized					47,100,000	47,100,000
Deferred revenue					47,100,000	47,100,000	28,800,000
Regeneron Pharmaceuticals Inc. [Member] | Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						10,700,000	10,400,000	2,700,000
Regeneron Pharmaceuticals Inc. [Member] | 2016 Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions						75,000,000
Regeneron Pharmaceuticals Inc. [Member] | 2016 Regeneron Agreement [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestone payments				$ 25,000,000
Regulatory based milestone payments under agreement				110,000,000
Sales based milestone payments under agreement				185,000,000
Regeneron Pharmaceuticals Inc. [Member] | Stock Purchase Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Purchase of common stock through private placement				$ 50,000,000
Regeneron Pharmaceuticals Inc. [Member] | 2020 Regeneron Amendment [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions	$ 70,000,000
Fee to extend collaboration arrangement	$ 25,000,000
Collaboration term extension period	2024-04
Regeneron Pharmaceuticals Inc. [Member] | 2020 Stock Purchase Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Common stock shares sold | shares	925,218
Common stock, par value | $ / shares	$ 0.0001
Cash consideration received on sale of common stock	$ 30,000,000
Sale of stock, price per share | $ / shares	$ 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%
Regeneron Pharmaceuticals Inc. [Member] | 2024 Technology Collaboration Extension [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amount allocated to licenses to targets and associated research activities and evaluation plans						48,300,000
Amount allocated to technology collaboration and associated research activities						3,400,000
Cumulative catch up adjustment					10,300,000	10,300,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement further option extension period		two years
Additional regeneron target cap | Targetcap			5
Number of unique ex vivo products commercialized | Product			10
Collaboration term extension period		2026-04
Collaboration revenue						21,000,000	24,100,000	25,700,000
Payments due						19,600,000	11,900,000	5,900,000
Deferred revenue		$ 30,000,000
Regeneron Pharmaceuticals Inc. [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable					35,700,000	35,700,000	3,200,000
ONK Therapeutics [Member] | Research Materials Shippmet Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						200,000	100,000
ONK Therapeutics [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable					0	0	100,000
Kyverna [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue					0	0	400,000
Revenue						400,000	6,600,000	0
Kyverna [Member] | Research Materials Shippmet Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue						100,000
Kyverna [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable					100,000	100,000	0
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						1,800,000	200,000	0
Deferred revenue					13,900,000	13,900,000	14,700,000
Sparing Vision [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable					500,000	500,000	100,000
AvenCell Member
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions						6,600,000	11,400,000	2,900,000
Collaboration revenue						13,200,000	22,800,000	5,900,000
Deferred revenue					0	0	19,900,000
AvenCell Member | Research Materials Shippmet Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						200,000	300,000
AvenCell Member | AvenCell Co/Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						600,000	2,000,000	$ 200,000
AvenCell Member | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable					$ 200,000	$ 200,000	$ 300,000

Equity-Method Investment and _2

Equity-Method Investment and Other Investments - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jul. 30, 2021
Schedule of Equity Method Investments [Line Items]
Equity method investment		$ 11,765	$ 32,455
Loss from equity method investments		(15,633)	(11,079)	$ (1,325)
AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment		11,800	32,500
Investment Owned, Fair Value					$ 62,900
Loss from equity method investments		6,600	11,400	2,900
Investments in and Advances to Affiliates, at Fair Value, Gross Reductions		14,100	14,300	$ 1,800
Sparing Vision [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, Fair Value	$ 14,800	14,800	14,800
Sparing Vision [Member] | Series A2 Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Number of preferred stock received	83,316
Kyverna Therapeutics Inc [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, Fair Value		$ 10,000	$ 10,000
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
Joint Venture AvenCell [Member] | AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		33.33%
Preferred Stock Purchase Agreement [Member] | Joint Venture AvenCell [Member] | AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage					33.33%
Preferred Stock Purchase Agreement [Member] | Joint Venture AvenCell [Member] | Cellex and BXLS [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage					66.67%

Rewrite Acquisition - Additiona

Rewrite Acquisition - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2023	Feb. 28, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Feb. 28, 2023
Business Acquisition [Line Items]
Research and development			$ 435,069	$ 419,979	$ 229,807
Common stock, shares issued			92,997,158	87,103,007
Rewrite Therapeutics Delaware Corporation [Member]
Business Acquisition [Line Items]
Upfront consideration payable in cash		$ 45,000
Research and development		56,000
Milestone payments		155,000
Cash		$ 130,000
Common stock, shares issued		25,000,000
Liability for milestone payment	$ 25,000	$ 10,500
Rewrite Therapeutics Delaware Corporation [Member] | Pre-specified Research Milestones [Member]
Business Acquisition [Line Items]
Milestone payments		55,000
Rewrite Therapeutics Delaware Corporation [Member] | Regulatory Approval Milestone [Member]
Business Acquisition [Line Items]
Milestone payments		$ 100,000
Rewrite Therapeutics Delaware Corporation [Member] | Rewrite Acquisition [Member]
Business Acquisition [Line Items]
Cash						$ 900
Common stock, shares issued in connection with research milestone	567,045

Rewrite Acquisition - Summary o

Rewrite Acquisition - Summary of Transaction Price Determined and Allocated (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Transaction Price
Upfront cash consideration	$ 43,730
Research contingent consideration liabilities	10,541
Transaction costs	1,838
Total transaction price	56,109
Transaction Price Allocated
In-process research and development	55,990
Cash acquired	287
Other current assets acquired	153
Other liabilities assumed	(321)
Total transaction price	$ 56,109

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	1 Months Ended							12 Months Ended
	Jun. 30, 2023 ft²	Jan. 31, 2023 ft²	Feb. 28, 2022 USD ($) ft²	Nov. 30, 2020	Mar. 31, 2019	Jan. 31, 2016	Oct. 31, 2014	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2021	Dec. 31, 2022 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets | $								$ 115,375		$ 133,076
Total operating lease liabilities at December 31, 2023 | $								$ 115,346
130 Brookline Street [Member]
Lessee Lease Description [Line Items]
Operating sublease, existence of option to extend					true
Operating lease, existence of option to terminate							true
130 Brookline Street [Member] | Second Amendment [Member]
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend									true
40 Erie Street [Member]
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend						true
Operating lease, existence of option to terminate						true
Operating lease, terminate term						6 years
40 Erie Street [Member] | Second Amendment [Member]
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend				true
Operating lease, terminate term				6 years
Albany Lease [Member]
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend									true
840 Winter Street Lease [Member]
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend			true
Operating lease, options to extend			The Company has the option to extend the 840 Winter Lease for two five-year terms.
Operating lease, term of contract			144 months
Area of space leased | ft²			140,000
Payments for rent | $			$ 146,000
Lease term			144 months
Operating lease, description			In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of office, general laboratory and planned good manufacturing practice (“GMP”) manufacturing space at 840 Winter Street in Waltham
Tenant improvement allowance per rentable square foot | ft²	400
Cambridge [Member]
Lessee Lease Description [Line Items]
Area of space leased | ft²		13,000						230,000

Leases - Summary of Lease Costs

Leases - Summary of Lease Costs and Other Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Lease cost
Operating lease cost	$ 27,849	$ 18,031
Variable lease cost	6,991	4,443
Sublease income	(1,439)	0
Net lease cost	33,401	22,474
Other information
Operating cash flows used for operating leases	25,456	14,656
Operating lease liabilities arising from obtaining right-of-use assets	$ 1,311	$ 67,053
Weighted average remaining lease term	6 years 2 months 12 days	6 years 10 months 24 days
Weighted average discount rate	7.37%	7.20%

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, 2023 USD ($)
Leases [Abstract]
2024	$ 26,395
2025	25,933
2026	25,110
2027	17,548
2028	12,300
Thereafter	39,260
Total lease payments	146,546
Less: imputed interest	(31,200)
Total operating lease liabilities at December 31, 2023	$ 115,346

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Equity-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 134,050	$ 91,400	$ 47,009
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	82,211	56,279	26,712
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 51,839	$ 35,121	$ 20,297

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Mar. 31, 2023 $ / shares shares	Mar. 31, 2022 Tranche $ / shares shares	May 31, 2016	May 30, 2016	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period					1 year 4 months 24 days
Common stock, shares issued					92,997,158	87,103,007
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares	$ 40.75				$ 41.3	$ 70.9	$ 73.81
Total fair value amount, Vested | $					$ 24,900	$ 10,400	$ 14,100
Number of Shares, Granted					3,047,544
Number of shares vested					677,055
Risk-free interest rate					4.40%	1.90%	1%
Number of tranches | Tranche		2
Expected dividend yield					0%	0%	0%
Expected volatility					78.70%	76.20%	72.90%
Expected term					6 years	5 years 10 months 24 days	6 years
Equity-based compensation expense | $					$ 134,050	$ 91,400	$ 47,009
Weighted average grant date fair value per share | $ / shares					$ 28.92	$ 57.23	$ 54.09
Total intrinsic value of stock options exercised | $					$ 7,600	$ 42,800	$ 262,000
Unrecognized compensation cost related to stock options | $					56,100
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized equity-based compensation expense related to restricted stock | $					$ 125,200
Weighted average period of unrecognized compensation costs					1 year 8 months 12 days
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period	3 years	3 years
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares		$ 79.85
Number of Shares, Granted	2,195,135	794,424
PSUs [Member] | Senior Executives [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period	3 years	3 years
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares	$ 68.55	$ 126.49
Number of Shares, Granted	181,743	55,144
Risk-free interest rate	4.60%	1.44%
Expected dividend yield	0%	0%
Expected volatility	84.34%	82.53%
Expected term	2 years 10 months 2 days	2 years 10 months 2 days
PSUs [Member] | Non-executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		66,296
First Anniversary of Original Vesting Date [Member] | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		21,878
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of stock options granted under the Plan					Stock options granted under the 2015 Plan in 2023 generally vest as to one-third on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining two 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					3,875,539
Percentage of cumulative increase in number of shares for future issuance					4%
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.
Percentage of fair market value of common stock			85%
Shares available for future issuance					1,077,487
Common stock, shares issued					142,079	77,618	30,897
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares					$ 27.65	$ 34.15	$ 65.51
Expected dividend yield					0%	0%	0%
Expected term					6 months	6 months	6 months
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

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) - $ / shares	1 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Number of Shares, Unvested, Beginning balance		1,941,379
Number of Shares, Granted		3,047,544
Number of Shares, Vested		(677,055)
Number of Shares, Cancelled		(270,115)
Number of Shares, Unvested, Ending balance		4,041,753	1,941,379
Weighted Average Grant Date Fair Value per Share, Unvested, Beginning balance		$ 70.7
Weighted Average Grant Date Fair Value per Share, Granted	$ 40.75	41.3	$ 70.9	$ 73.81
Weighted Average Grant Date Fair Value per Share, Vested		68.04
Weighted Average Grant Date Fair Value per Share, Cancelled		49.41
Weighted Average Grant Date Fair Value per Share, Unvested, Ending balance		$ 50.4	$ 70.7

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate	4.40%	1.90%	1%
Expected term	6 years	5 years 10 months 24 days	6 years
Expected volatility of underlying stock	78.70%	76.20%	72.90%
Expected dividend yield	0%	0%	0%
2016 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate, Minimum	4.70%	0.22%	0.05%
Risk-free interest rate , Maximum	5.53%	2.52%	0.09%
Expected term	6 months	6 months	6 months
Expected volatility of underlying stock, Minimum	60.40%	63.60%	77.50%
Expected volatility of underlying stock, Maximum	69.20%	95.30%	109.20%
Expected dividend yield	0%	0%	0%

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding, Beginning Balance | shares	5,471,675
Number of options, Granted | shares	569,821
Number of options, Exercised | shares	(385,130)
Number of options, Forfeited | shares	(197,367)
Number of Options, Outstanding, Ending Balance | shares	5,458,999
Number of Options, Exercisable | shares	4,017,227
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance | $ / shares	$ 49.86
Weighted Average Exercise Price per Share, Granted | $ / shares	41
Weighted Average Exercise Price per Share, Exercised | $ / shares	17.13
Weighted Average Exercise Price per Share, Forfeited | $ / shares	73.9
Weighted Average Exercise Price per Share, Outstanding, Ending Balance | $ / shares	50.38
Weighted Average Exercise Price per Share, Exercisable | $ / shares	$ 43.63
Weighted Average Remaining Contractual Term, Outstanding	6 years 7 months 24 days
Weighted Average Remaining Contractual Term, Exercisable	6 years 1 month 20 days
Aggregate Intrinsic Value, Outstanding | $	$ 35,922
Aggregate Intrinsic Value, Exercisable | $	$ 34,790

Loss Per Share - Schedule of Ba

Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Income (Loss)	$ (481,192)	$ (474,186)	$ (267,892)
Weighted average shares outstanding, basic	88,770	76,972	70,894
Weighted average shares outstanding, diluted	88,770	76,972	70,894
Net Loss Per Share, Basic	$ (5.42)	$ (6.16)	$ (3.78)
Net Loss Per Share, Diluted	$ (5.42)	$ (6.16)	$ (3.78)

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, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	9,501	7,413	6,758
Unvested Restricted Stock Units [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	4,042	1,941	453
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	5,459	5,472	6,305

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended				3 Months Ended	12 Months Ended
	Dec. 02, 2022	Jul. 02, 2021	Jun. 29, 2021	Dec. 31, 2023	Nov. 30, 2022	Mar. 31, 2022	Aug. 31, 2019	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock, shares authorized				240,000,000					240,000,000	120,000,000
Common stock, par value				$ 0.0001					$ 0.0001	$ 0.0001
Weighted Average Remaining Contractual Term, Exercisable									6 years 1 month 20 days
Follow On Public Offering
Class Of Stock [Line Items]
Proceeds from common stock offering									$ 0	$ 337,892	$ 648,315
Prepaid Expenses and Other Current Assets [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering									2,100
2019 Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering								$ 38,900
Percentage of gross proceeds from common stock as sales agent cash commission							3%
Stock Issued During Period, Shares, New Issues							3,778,889	579,788
Common stock price per share						$ 69.43		$ 69.43
2019 Sales Agreement [Member] | Maximum [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering							$ 150,000
2022 Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering									$ 121,900	$ 189,000
Percentage of gross proceeds from common stock as sales agent cash commission						3%
Stock Issued During Period, Shares, New Issues				7,518,163					4,122,824	3,395,339
Common stock price per share				$ 30.57					$ 30.57	$ 57.43
Proceeds from common stock offering				$ 79,000					$ 79,000
2022 Sales Agreement [Member] | Maximum [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering						$ 400,000
Underwriting Agreement [Member] | Follow On Public Offering
Class Of Stock [Line Items]
Proceeds from common stock offering	$ 337,900	$ 648,300
Stock Issued During Period, Shares, New Issues			4,758,620		6,550,219
Common stock price per share			$ 145		$ 45.8
Common stock, par value			$ 0.0001		$ 0.0001
Shares available for future issuance			620,689		982,532
Weighted Average Remaining Contractual Term, Exercisable					30 days

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Deferred revenue current	$ 22,140	$ 43,839
Collaboration revenue	36,275	52,121	$ 33,053
Revenue	6,600	11,400	2,900
AvenCell Member
Related Party Transaction [Line Items]
Collaboration revenue	$ 13,200	22,800	5,900
Joint Venture AvenCell [Member] | AvenCell Member
Related Party Transaction [Line Items]
Equity method investment, ownership percentage	33.33%
AvencellLca
Related Party Transaction [Line Items]
Revenue	$ 13,200	22,800	5,900
AvencellCoCo
Related Party Transaction [Line Items]
Collaboration revenue			$ 200
Revenue	600
Contra Revenue		2,000
Aggregate transaction price remaining to be recognized	0
Materials Shipped
Related Party Transaction [Line Items]
Revenue	$ 200	$ 300

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Detail) - 401(k) plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Employer matching contribution of employee contribution, percent	50%
Employer matching contribution, percent	6%
Employer discretionary contribution amount	$ 3.3	$ 2.7	$ 1.6