bluebird bio (BLUE) 10-Q 9 May 23 2023 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2023	May 05, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	001-35966
Entity Registrant Name	bluebird bio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3680878
Entity Address, Address Line One	455 Grand Union Boulevard
Entity Address, City or Town	Somerville
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02145
City Area Code	339
Local Phone Number	499-9300
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	BLUE
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		106,412,001
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001293971
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 239,045	$ 113,006
Marketable securities	79,212	67,321
Prepaid expenses	13,466	8,374
Inventory	3,809	0
Receivables and other current assets	15,539	10,787
Total current assets	351,071	199,488
Marketable securities	0	1,414
Property, plant and equipment, net	8,718	9,362
Goodwill	5,646	5,646
Intangible Assets	5,613	4,868
Operating lease right-of-use assets	270,153	281,996
Restricted cash and other non-current assets	51,535	52,128
Total assets	692,736	554,902
Current liabilities:
Accounts payable	19,235	25,092
Accrued expenses and other current liabilities	45,294	51,985
Operating lease liability, current portion	51,404	51,160
Total current liabilities	115,933	128,237
Operating lease liability, net of current portion	221,971	230,230
Other non-current liabilities	92	92
Total liabilities	337,996	358,559
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.01 par value, 5,000 shares authorized; 0 shares issued and outstanding at March 31, 2023 and December 31, 2022	0	0
Common stock, $0.01 par value, 125,000 shares authorized; 106,370 and 82,923 shares issued and outstanding at March 31, 2023 and December 31, 2022, respectively	1,064	830
Additional paid-in capital	4,322,025	4,186,086
Accumulated other comprehensive loss	(3,086)	(4,070)
Accumulated deficit	(3,965,263)	(3,986,503)
Total stockholders’ equity	354,740	196,343
Total liabilities and stockholders’ equity	$ 692,736	$ 554,902

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Stockholders’ equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issued (in shares)	106,370,000	82,923,000
Common stock, shares outstanding (in shares)	106,370,000	82,923,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) shares in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue:
Total revenues	$ 2,381,000	$ 1,945,000
Cost of product revenue	3,376,000	8,310,000
Gross margin	(995,000)	(6,365,000)
Operating expenses:
Selling, general and administrative	37,354,000	36,106,000
Research and development	46,144,000	77,875,000
Total operating expenses	83,498,000	113,981,000
Gain from sale of priority review voucher, net	92,930,000	0
Income (loss) from operations	8,437,000	(120,346,000)
Interest income, net	2,825,000	106,000
Other income (expense), net	9,978,000	(1,912,000)
Income (loss) before income taxes	21,240,000	(122,152,000)
Income tax (expense) benefit	0	0
Net income (loss)	$ 21,240,000	$ (122,152,000)
Net income (loss) per share - basic (in dollars per share)	$ 0.21	$ (1.66)
Net income (loss) per share - diluted (in dollars per share)	$ 0.21	$ 0
Weighted-average number of common shares used in computing net income (loss) per share - basic (in shares)	102,920	73,688
Weighted-average number of common shares used in computing net income (loss) per share - diluted (in shares)	103,303	0
Other comprehensive income (loss):
Total other comprehensive income (loss)	$ 984,000	$ (1,548,000)
Comprehensive income (loss)	22,224,000	(123,700,000)
Product revenue, net
Revenue:
Revenue	2,296,000	1,408,000
Other revenue
Revenue:
Revenue	$ 85,000	$ 537,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Other comprehensive income (loss), tax	$ 0	$ 0

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated other comprehensive income (loss)	Accumulated deficit
Beginning balance (in shares) at Dec. 31, 2021		71,115
Beginning balance at Dec. 31, 2021	$ 374,277	$ 711	$ 4,096,402	$ (2,911)	$ (3,719,925)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		310
Vesting of restricted stock units	0	$ 3	(3)
Exercise of stock options (in shares)		1
Exercise of stock options	1		1
Stock-based compensation	12,681		12,681
Issuance of stock awards (in shares)		12
Other comprehensive income (loss)	(1,548)			(1,548)
Net income (loss)	(122,152)				(122,152)
Ending balance, shares (in shares) at Mar. 31, 2022		71,438
Ending balance at Mar. 31, 2022	$ 263,259	$ 714	4,109,081	(4,459)	(3,842,077)
Beginning balance (in shares) at Dec. 31, 2022	82,923	82,923
Beginning balance at Dec. 31, 2022	$ 196,343	$ 830	4,186,086	(4,070)	(3,986,503)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted stock units (in shares)		382
Vesting of restricted stock units	$ (195)	$ 3	(198)
Exercise of stock options (in shares)	3	3
Exercise of stock options	$ 7		7
Purchase of common stock under ESPP (in shares)		62
Purchase of common stock under ESPP	227	$ 1	226
Issuance of common stock (in shares)		23,000
Issuance of common stock	130,291	$ 230	130,061
Stock-based compensation	5,843		5,843
Other comprehensive income (loss)	984			984
Net income (loss)	$ 21,240				21,240
Ending balance, shares (in shares) at Mar. 31, 2023	106,370	106,370
Ending balance at Mar. 31, 2023	$ 354,740	$ 1,064	$ 4,322,025	$ (3,086)	$ (3,965,263)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net income (loss)	$ 21,240	$ (122,152)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	1,082	1,014
Stock-based compensation expense	5,391	12,390
Gain from sale of priority review voucher	(92,930)	0
Loss (gain) on equity securities	0	2,508
Excess inventory reserve	228	7,519
Other non-cash items	237	189
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(9,335)	(4,303)
Inventory	(3,586)	(8,756)
Operating lease right-of-use assets	11,829	6,517
Accounts payable	(6,443)	2,467
Accrued expenses and other liabilities	(9,065)	(16,561)
Operating lease liabilities	(8,001)	(6,128)
Deferred revenue	2,715	0
Net cash used in operating activities	(86,638)	(125,296)
Cash flows from investing activities:
Purchase of property, plant and equipment	(232)	(857)
Purchases of marketable securities	(19,610)	0
Proceeds from maturities of marketable securities	4,021	70,783
Proceeds from sales of marketable securities	5,853	0
Purchase of intangible assets	(868)	0
Proceeds from sale of priority review voucher	92,972	0
Net cash provided by investing activities	82,136	69,926
Cash flows from financing activities:
Proceeds from exercise of stock options and ESPP contributions	7	9
Net cash provided by financing activities	130,456	9
(Decrease) increase in cash, cash equivalents and restricted cash	125,954	(55,361)
Cash, cash equivalents and restricted cash at beginning of period	158,445	206,693
Cash, cash equivalents and restricted cash at end of period	284,399	151,332
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	239,045	106,260
Restricted cash included in receivables and other current assets	1,417	1,822
Restricted cash included in restricted cash and other non-current assets	43,937	43,250
Total cash, cash equivalents and restricted cash	284,399	151,332
Supplemental cash flow disclosures from investing and financing activities:
Purchases of property, plant and equipment included in accounts payable and accrued expenses	189	2,134
Offering expenses accrued or in AP	523	0
Priority review voucher expenses accrued or in AP	43	0
Right-of-use assets obtained in exchange for operating lease liabilities	0	26,882
Cash paid during the period for income taxes	2	0
Private Placement
Cash flows from financing activities:
Proceeds from issuance of common stock	(196)	0
Public Offering
Cash flows from financing activities:
Proceeds from issuance of common stock	$ 130,645	$ 0

Equity (Details)

Equity (Details) - USD ($) shares in Millions, $ in Millions		3 Months Ended
	Jan. 18, 2023	Mar. 31, 2023
Statement of Stockholders' Equity [Abstract]
Issuance of common stock (in shares)	20
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Shares issued, price per share (in dollars per share)	$ 6
Option to purchase additional shares, exercise period	30 days
Option to purchase additional shares (in shares)	3
Shares of common stock sold (in shares)		23
Gross proceeds		$ 138
Offering costs		$ 130.5

Description of the business

Description of the business	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the business	Description of the business bluebird bio, Inc. (the “Company” or “bluebird”) was incorporated in Delaware on April 16, 1992, and is headquartered in Somerville, Massachusetts. The Company is a biotechnology company committed to researching, developing, and commercializing potentially curative transformative gene therapies for severe genetic diseases based on our lentiviral vector (“LVV”) gene addition platform. In 2022, following more than a decade of leadership in research and clinical development, the Company received approval from the U.S. Food and Drug Administration (the “FDA”) for two gene therapies, both of which were recently launched. On August 17, 2022, ZYNTEGLO (betibeglogene autotemcel, also known as beti-cel), was approved by the FDA for the treatment of adult and pediatric patients with ß-thalassemia who require regular red blood cell transfusions. On September 16, 2022, the FDA granted Accelerated Approval of SKYSONA (elivaldogene autotemcel, also known as eli-cel), to slow the progression of neurologic dysfunction in boys 4-17 years of age with early active cerebral adrenoleukodystrophy (“CALD”). On April 24, 2023, the Company announced that it had submitted a biologics licensing application (“BLA”) to the FDA for its third gene therapy candidate -- lovotibeglogene autotemcel – also known as lovo-cel – requesting priority review of the treatment for patients 12 and older with sickle cell disease (“SCD”) with a history of vaso-occlusive-events. The Company is focusing its development and commercialization efforts in the U.S. market. The Company has obtained the withdrawal of the marketing authorization for beti-cel in the European Union, which became effective on March 24, 2022. On November 18, 2021, the Company obtained the withdrawal of the marketing authorization for eli-cel in the European Union. The Company withdrew its marketing applications for beti-cel and eli-cel from the MHRA in the United Kingdom. The Company is continuing the long-term follow-up of patients previously enrolled within the clinical trial programs in Europe as planned but do not intend to initiate any new clinical trials in Europe for β- thalassemia, CALD or SCD. Since its inception in 1992, the Company has devoted substantially all of its resources to its development and commercialization efforts relating to its products and product candidates, including activities to manufacture product candidates in compliance with good manufacturing practices ("GMP") to conduct clinical studies of its product candidates, to provide selling, general and administrative support for these operations, to market, commercially manufacture and distribute its approved products and to protect its intellectual property. The Company has not generated material revenue from product sales. The Company has funded its operations primarily through the sale of common stock in its public offerings, private placements of preferred stock and warrants, the sale of two Rare Pediatric Disease Priority Review Vouchers ("PRVs") and through collaborations. In August 2022 and September 2022 the Company received the two PRVs under a U.S. Food and Drug Administration program intended to encourage the development of treatments for rare pediatric diseases. In January 2023, the Company sold its second PRV for aggregate net proceeds of $92.9 million. In January 2023, the Company sold 23.0 million shares of common stock (inclusive of shares sold pursuant to an option to the underwriters in connection with the offering) through an underwritten public offering at a price of $6.00 per share for aggregate net proceeds of $130.5 million. In April 2022, the Board of Directors of the Company approved a comprehensive restructuring plan intended to reduce operating expenses and enhance the Company’s focus on achieving FDA approval for its programs in the U.S. As part of the restructuring, the Company reduced its workforce by approximately 30% across the second and third quarters of 2022. Refer to Note 14, Restructuring, for more information on this restructuring. In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. As of March 31, 2023, the Company had an accumulated deficit of $3.97 billion. During the three months ended March 31, 2023, the Company had net income of $21.2 million and used $86.6 million of cash in operations. As of March 31, 2023, the Company had cash, cash equivalents and marketable securities of $318.3 million. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that these consolidated financial statements are issued. In performing its analysis, management excluded certain elements of its operating plan that cannot be considered probable. Under ASC 205-40, the future receipt of potential funding from future equity or debt issuances and the release of restricted cash related to the Company’s 50 Binney Street sublease cannot be considered probable at this time because these plans are not entirely within the Company’s control nor have been approved by the Board of Directors as of the date of these consolidated financial statements. The Company's expectation to generate operating losses and negative operating cash flows in the future and the need for additional funding to support its planned operations raise substantial doubt regarding the Company’s ability to continue as a going concern for a period of one year after the date that these consolidated financial statements are issued. Management's plans to alleviate the conditions that raise substantial doubt include evaluating 2023 spending, including realized savings through the move of the Company's headquarters to Assembly Row in Somerville, Massachusetts, and the pursuit of additional cash resources through public or private equity or debt financings. Management has concluded the likelihood that its plan to successfully obtain sufficient funding from one or more of these sources, or adequately reduce expenditures, while reasonably possible, is less than probable. Accordingly, the Company has concluded that substantial doubt exists about the Company’s ability to continue as a going concern for a period of at least 12 months from the date of issuance of these consolidated financial statements. The Company will assess on a quarterly basis whether the determination for estimates remain appropriate based on actual data observed. However, the Company has based this estimate on assumptions that may prove to be wrong, and its operating plan may change as a result of many factors currently unknown to it. As a result, the Company could deplete its capital resources sooner than it currently expects. The Company expects to finance its future cash needs through the issuance of equity, or debt, or other alternative means. If the Company is unable to obtain funding on a timely basis, or if revenues from collaboration arrangements or product sales are less than it has projected, the Company may be required to further revise its business plan and strategy, which may result in the Company significantly curtailing, delaying or discontinuing one or more of our research or development programs or the commercialization of any product candidates or may result in the Company being unable to expand its operations or otherwise capitalize on its business opportunities. As a result, the Company's business, financial condition and results of operations could be materially affected. The accompanying financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of the uncertainties described above.

Basis of presentation, principl

Basis of presentation, principles of consolidation and significant accounting policies	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of presentation, principles of consolidation and significant accounting policies	Basis of presentation, principles of consolidation and significant accounting policies Basis of presentation The accompanying condensed consolidated financial statements are unaudited and have been prepared by the Company in accordance with accounting principles generally accepted in the United States (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States GAAP as included in the ASC and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended March 31, 2023 and 2022. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2022, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022, filed with the Securities and Exchange Commission (the “SEC”) on March 29, 2023 (the "2022 Annual Report on Form 10-K"). Amounts reported are computed based on thousands, except percentages, per share amounts or as otherwise noted. As a result, certain totals may not sum due to rounding. The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The Company views its operations and manages its business in one operating segment. Significant accounting policies The significant accounting policies used in preparation of these condensed consolidated financial statements for the three months ended March 31, 2023 are consistent with those discussed in Note 2 to the consolidated financial statements included in the Company’s 2022 Annual Report on Form 10-K. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements. Estimates and judgments are used in the following areas, among others: future undiscounted cash flows and subsequent fair value estimates used to assess potential and measure any impairment of long-lived assets, including goodwill and intangible assets, and the measurement of right-of-use assets and lease liabilities, stock-based compensation expense, accrued expenses, income taxes, gross to net revenue reserves, inventory reserved, and the assessment of the Company's ability to fund its operations for at least the next twelve months from the date of issuance of these financial statements. Inventory Inventories are stated at the lower of cost or net realizable value under the first-expired, first-out ("FEFO") methodology. Given human gene therapy products are a new and novel category of therapeutics and future economic benefit is not probable until regulatory approval for the product has been obtained, the Company has only considered inventory for capitalization upon and after regulatory approval. Manufacturing costs incurred prior to regulatory approval for pre-launch inventory that did not qualify for capitalization and clinical manufacturing costs were charged to research and development expense in the Company’s consolidated statements of operations and comprehensive loss as costs were incurred. Additionally, inventory that initially qualifies for capitalization but that may ultimately be used for the production of clinical drug product is expensed as research and development expense when it has been designated for the manufacture of clinical drug product. Inventory consists of cell banks, plasmids, lentiviral vector ("LVV"), other materials and compounds sourced from third party suppliers and utilized in the manufacturing process, and drug product, which has been produced for the treatment of specific patients, that are owned by the Company. Management periodically reviews inventories for excess or obsolescence, considering factors such as sales forecasts compared to quantities on hand and firm purchase commitments as well as remaining shelf life of on hand inventories. The Company writes-down its inventory that is obsolete or otherwise unmarketable to its estimated net realizable value in the period in which the impairment is first identified. Any such adjustments are included as a component of cost of goods sold within cost of product revenue on the Company’s consolidated statements of operations and comprehensive loss. Revenue recognition Under ASC Topic 606, Revenue from Contracts with Customers (“Topic 606”), an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer. Once a contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (“SSP”) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price 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 in the period of adjustment. If a license arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached 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, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company assessed each of its revenue generating arrangements in order to determine whether a significant financing component exists and concluded that a significant financing component does not exist in any of its arrangements. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, at a point in time. The Company recognizes revenue within the following financial statement captions: Product revenue, net The Company recognizes product revenue, net in accordance with Topic 606. Product revenue, net represents sales of ZYNTEGLO and SKYSONA. In 2022, the Company received approval of ZYNTEGLO and SKYSONA from the FDA. The amount of revenue recognized by the Company is equal to the amount of consideration that is expected to be received from the sale of product to its customers. The Company has Specialty Distributors ("SD") and Specialty Pharmacies ("SP") that deliver product to the Qualified Treatment Centers ("QTC"). Revenue is only recognized when the performance obligation is satisfied. The Company will recognize revenue upon infusion to the patient. To determine whether a significant reversal will occur in future periods, the Company will assess both the likelihood and magnitude of any such potential reversal of revenue. Other revenue In 2021, the Company entered into a grant agreement with the Bill and Melinda Gates Foundation. The Company recognizes grant revenue in accordance with ASC 958-605, Revenue Recognition Not-for-Profit Entities , when qualifying costs are incurred and barriers to restriction have been overcome. When grant funds are received after costs have been incurred, the Company records revenue and a corresponding grant receivable. Cash received from grants in advance of incurring qualifying costs is recorded as deferred revenue and recognized as revenue when qualifying costs are incurred. In 2023, the Company ceased further research work and is in the process of winding down such collaboration. Recent accounting pronouncements During the periods presented, the Company was not required to adopt any recently issued accounting standards. The Company does not expect any recently issued accounting standards to have a material impact on its financial statements.

Marketable securities

Marketable securities	3 Months Ended
	Mar. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable securities	Marketable securities The following table summarizes the marketable securities held at March 31, 2023 and December 31, 2022 (in thousands): Description Amortized cost / Cost Unrealized gains Unrealized losses Fair value March 31, 2023 U.S. government agency securities and treasuries $ 79,600 $ 4 $ (883) $ 78,721 Corporate bonds 500 — (9) 491 Total $ 80,100 $ 4 $ (892) $ 79,212 December 31, 2022 U.S. government agency securities and treasuries $ 67,970 $ — $ (1,733) $ 66,237 Corporate bonds 2,524 — (26) 2,498 Total $ 70,494 $ — $ (1,759) $ 68,735 No available-for-sale debt securities held as of March 31, 2023 or December 31, 2022 had remaining maturities greater than five years.

Fair value measurements

Fair value measurements	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Fair value measurements	Fair value measurements The following table sets forth the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2023 and December 31, 2022 (in thousands): Description Total Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) March 31, 2023 Assets: Cash and cash equivalents $ 239,045 $ 239,045 $ — $ — Marketable securities: U.S. government agency securities and treasuries 78,721 — 78,721 — Corporate bonds 491 — 491 — Total $ 318,257 $ 239,045 $ 79,212 $ — December 31, 2022 Assets: Cash and cash equivalents $ 113,006 $ 113,006 $ — $ — Marketable securities: U.S. government agency securities and treasuries 66,237 — 66,237 — Corporate bonds 2,498 — 2,498 — Total $ 181,741 $ 113,006 $ 68,735 $ — Cash and cash equivalents The Company considers all highly liquid securities with original final maturities of 90 days or less from the date of purchase to be cash equivalents. As of March 31, 2023 and December 31, 2022, cash and cash equivalents comprise funds in cash and money market accounts held at multiple banking and asset management institutions. Marketable securities Marketable securities classified as Level 2 within the valuation hierarchy generally consist of U.S. government agency securities and treasuries, corporate bonds, and commercial paper. The Company estimates the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for the same or similar securities, issuer credit spreads, benchmark yields, and other observable inputs. The Company validates the prices provided by its third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances. The amortized cost of available-for-sale debt securities is adjusted for amortization of premiums and accretion of discounts to the earliest call date for premiums or to maturity for discounts. At March 31, 2023 and December 31, 2022, the balance in the Company’s accumulated other comprehensive loss was composed primarily of activity related to the Company’s available-for-sale debt securities. There were $0.1 million and no realized loss recognized on the sale or maturity of available-for-sale debt securities during the three months ended March 31, 2023 and 2022, respectively. Accrued interest receivable on the Company's available-for-sale debt securities totaled $0.6 million and $0.1 million as of March 31, 2023 and December 31, 2022, respectively. No accrued interest receivable was written off during the three months ended March 31, 2023 or 2022. The following table summarizes available-for-sale debt securities in a continuous unrealized loss position for less than and greater than twelve months, and for which an allowance for credit losses has not been recorded at March 31, 2023 and December 31, 2022 (in thousands): Less than 12 months 12 months or greater Total Description Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses March 31, 2023 U.S. government agency securities $ 9,767 $ — $ 59,099 $ (883) $ 68,866 $ (883) Corporate bonds — — 491 (9) 491 (9) Total $ 9,767 $ — $ 59,590 $ (892) $ 69,357 $ (892) December 31, 2022 U.S. government agency securities $ — $ — $ 66,237 $ (1,733) $ 66,237 $ (1,733) Corporate bonds — — 2,498 (26) 2,498 (26) Total $ — $ — $ 68,735 $ (1,759) $ 68,735 $ (1,759)

Inventory

Inventory	3 Months Ended
	Mar. 31, 2023
Inventory Disclosure [Abstract]
Inventory	Inventory Inventory, net, consists of the following (in thousands): As of March 31, 2023 As of December 31, 2022 Raw materials $ — $ — Work in progress 3,029 — Finished goods 780 — Inventory $ 3,809 $ — Raw materials inventory consists of completed materials meeting quality acceptance standards to be used in the manufacture of drug product. Materials may include small molecules, plasmids, or vector products. Work in progress inventory consists of materials that are either partially completed or fully manufactured but are pending quality acceptance. Finished goods are completed drug product having full quality acceptance that may be shipped to a qualified treatment center, but has not yet been infused in the patient. As of December 31, 2022, the Company did not have any manufactured inventory that was in progress or had received final quality acceptance after the FDA approval of ZYNTEGLO or SKYSONA. Prior to FDA approval, the existing inventory was expensed to R&D expense.

Property, plant and equipment,

Property, plant and equipment, net	3 Months Ended
	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Property, plant and equipment, net	Property, plant and equipment, net Property, plant and equipment, net, consists of the following (in thousands): As of March 31, 2023 As of December 31, 2022 Laboratory equipment $ 22,835 $ 25,092 Computer equipment and software 1,861 1,854 Office equipment 4,510 4,348 Construction-in-progress 80 — Total property, plant and equipment 29,286 31,294 Less accumulated depreciation and amortization (20,568) (21,932) Property, plant and equipment, net $ 8,718 $ 9,362

Accrued expenses and other curr

Accrued expenses and other current liabilities	3 Months Ended
	Mar. 31, 2023
Payables and Accruals [Abstract]
Accrued expenses and other current liabilities	Accrued expenses and other current liabilities Accrued expenses and other current liabilities consist of the following (in thousands): As of March 31, 2023 As of December 31, 2022 Accrued manufacturing costs $ 5,586 $ 7,199 Accrued goods and services 9,655 8,134 Accrued clinical and contract research organization costs 14,005 12,368 Accrued employee compensation 9,291 20,095 Accrued professional fees 1,599 1,939 Deferred revenue, current portion 4,217 1,502 Other 941 748 Total accrued expenses and other current liabilities $ 45,294 $ 51,985

Leases

Leases	3 Months Ended
	Mar. 31, 2023
Leases [Abstract]
Leases	LeasesThe Company leases certain office and laboratory space, primarily located in Somerville, Massachusetts. Additionally, the Company has embedded leases through its agreements with contract manufacturing organizations in both the United States and internationally. There have been no material changes in lease obligations from those disclosed in Note 10 to the consolidated financial statements included in the Company's 2022 Annual Report on Form 10-K.

Commitments and contingencies

Commitments and contingencies	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Other funding commitments The Company is party to various agreements, principally relating to licensed technology, that require future payments relating to milestones that may be met in subsequent periods or royalties on future sales of specified products. The Company may be obligated to make future development, regulatory, and commercial milestone payments, and royalty payments on future sales of specified products associated with its collaboration and license agreements. Payments under these agreements generally become due and payable upon achievement of such milestones or sales. When the achievement of these milestones or sales have occurred, the corresponding amounts are recognized in the Company’s financial statements. Additionally, the Company is party to various contracts with contract research organizations and contract manufacturers that generally provide for termination on notice, with the exact amounts in the event of termination to be based on the timing of the termination and the terms of the agreement. As compared to the contractual obligations and commitments as disclosed in the Company's 2022 Annual Report on Form 10-K, the Company's future minimum purchase commitments as of the three months ended March 31, 2023 increased by $3.3 million. While there are no material legal proceedings the Company is aware of, the Company may become party to various claims and complaints arising in the ordinary course of business, including securities class action litigation. The Company enters into standard indemnification agreements in the ordinary course of business. Pursuant to the agreements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally the Company’s business partners. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is generally unlimited. Management does not believe that any ultimate liability resulting from any of these claims will have a material adverse effect on its results of operations, financial position, or liquidity. However, management cannot give any assurance regarding the ultimate outcome of any claims, and their resolution could be material to operating results for any particular period. The Company also indemnifies each of its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company's request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and by-laws. The term of the indemnification period lasts as long as such officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity. The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with the Company's exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, it has not recognized any liabilities relating to these obligations.

Equity

Equity	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Equity	EquityOn January 18, 2023, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Goldman Sachs & Co. LLC and J.P. Morgan Securities LLC in connection with the public offering, issuance and sale by the Company of 20.0 million shares of the Company’s common stock, $0.01 par value per share, at a public offering price of $6.00 per share, less underwriting discounts and commissions. Under the terms of the Underwriting Agreement, the Company also granted the underwriters an option exercisable for 30 days to purchase up to an additional 3.0 million shares of Common Stock at the public offering price, less underwriting discounts and commissions, which the underwriters exercised in full. The offering closed on January 23, 2023.For the three months ended March 31, 2023 the Company sold 23.0 million shares of common stock for gross proceeds of $138.0 million ($130.5 million net of offering costs), pursuant to the Underwriting Agreement.

Stock-based compensation

Stock-based compensation	3 Months Ended
	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-based compensation	Stock-based compensation In January 2023 and 2022, the number of shares of common stock available for issuance under the 2013 Stock Option and Incentive Plan (“2013 Plan”) was increased by approximately 3.3 million and 2.8 million shares, respectively, as a result of the automatic increase provision of the 2013 Plan. As of March 31, 2023, the total number of shares of common stock available for issuance under the 2013 Plan was approximately $5.9 million. Stock-based compensation expense The Company recognized stock-based compensation expense totaling $5.4 million and $12.4 million during the three months ended March 31, 2023 and 2022, respectively. Stock-based compensation expense recognized by award type is included within the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): For the three months ended March 31, 2023 2022 Stock options $ 1,723 $ 5,260 Restricted stock units 3,668 7,034 Employee stock purchase plan and other — 96 $ 5,391 $ 12,390 Stock-based compensation expense by classification included within the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): For the three months ended March 31, 2023 2022 Cost of Product Revenue $ 103 $ — Selling, general and administrative 2,361 5,835 Research and development 2,927 6,555 $ 5,391 $ 12,390 As of March 31, 2023, the Company had $0.5 million of stock compensation expense that was capitalized into inventory. Stock options The following table summarizes the stock option activity under the Company’s equity award plans and have been adjusted to reflect the effects of the November 2021 separation of our severe genetic disease and oncology programs into two separate, publicly traded companies: Shares (in thousands) Weighted- average exercise price per share Outstanding at December 31, 2022 2,668 $ 24.38 Granted 1,642 $ 5.26 Exercised (3) $ 2.74 Canceled or forfeited (73) $ 36.23 Outstanding at March 31, 2023 4,234 $ 16.77 Exercisable at March 31, 2023 1,313 $ 36.51 Vested and expected to vest at March 31, 2023 4,234 $ 16.77 During the three months ended March 31, 2023, less than 0.1 million stock options were exercised, resulting in total proceeds to the Company of less than $0.1 million. Restricted stock units The following table summarizes the restricted stock unit activity under the Company’s equity award plans: Shares Weighted- Unvested at December 31, 2022 2,415 $ 11.44 Granted 2,503 $ 5.20 Vested (326) $ 20.01 Forfeited (107) $ 7.56 Unvested at March 31, 2023 4,485 $ 7.70 Employee stock purchase plan In June 2013, the Company adopted its 2013 Employee Stock Purchase Plan (“2013 ESPP”), which authorized the initial issuance of up to a total of 0.2 million shares of the Company’s common stock to participating employees. In June 2021, the Company amended the 2013 ESPP to authorize an additional 1.4 million shares of the Company’s common stock available to participating employees. During the three months ended March 31, 2023 and 2022, less than 0.1 million shares and no shares, respectively, of common stock were issued under the 2013 ESPP.

Income taxes

Income taxes	3 Months Ended
	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Income taxes	Income taxes Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax basis of assets and liabilities using statutory rates. A valuation allowance is recorded against deferred tax assets if it is more likely than not that some or all of the deferred tax assets will not be realized. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company’s otherwise recognizable net deferred tax assets. The tax expense recognized during the three months ended March 31, 2023 is $0 due to the wind down of our operations in Europe and the full valuation allowance. On August 16, 2022, the Inflation Reduction Act (“IRA”) was enacted and introduced a 15% corporate alternative minimum tax (”CAMT”) for corporations with average annual adjusted financial statement income for any three-year tax period ending after December 31, 2021 and preceding tax year exceeding $1 billion, effective for tax years beginning after December 31, 2021, as well as a 1% excise tax on stock repurchases made by public companies. The Company has concluded that the provisions in the IRA have an immaterial impact on the Company’s income tax expense due to its cumulative losses and full valuation allowance position.

Net loss per share

Net loss per share	3 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
Net loss per share	Net loss per share The computation of basic earnings per share (EPS) is based on the weighted-average number of outstanding shares of the Company's common stock. The computation of diluted EPS is based on the weighted-average number of outstanding shares of the Company's common stock and potential dilutive shares during the period as determined by using the treasury stock method. Basic and diluted EPS for the three months ended March 31, 2023 and 2022 were calculated as follows (in thousands except per share data): For the three months ended 2023 2022 Numerator: Net Income 21,240 (122,152) (1) Denominator: Basic weighted-average common shares outstanding 102,920 Effect of dilutive securities 383 Diluted weighted-average common shares outstanding 103,303 Basic EPS $ 0.21 Diluted EPS $ 0.21

Restructuring

Restructuring	3 Months Ended
	Mar. 31, 2023
Restructuring and Related Activities [Abstract]
Restructuring	RestructuringIn April 2022, the Board of Directors of the Company approved a comprehensive restructuring plan intended to reduce operating expenses. As part of the restructuring, the Company reduced its workforce by nearly 30% across the second and third quarters of 2022. The Company incurred approximately $4.9 million in costs to implement the restructuring, comprised primarily of severance payments and continuing health care coverage over the severance period. The restructuring actions associated with these charges commenced in April 2022, and were completed by September 30, 2022.

Basis of presentation, princi_2

Basis of presentation, principles of consolidation and significant accounting policies (Policies)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying condensed consolidated financial statements are unaudited and have been prepared by the Company in accordance with accounting principles generally accepted in the United States (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States GAAP as included in the ASC and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended March 31, 2023 and 2022.
Consolidation	The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The Company views its operations and manages its business in one operating segment.
Discontinued operations
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. This process may result in actual results differing materially from those estimated amounts used in the preparation of the financial statements. Estimates and judgments are used in the following areas, among others: future undiscounted cash flows and subsequent fair value estimates used to assess potential and measure any impairment of long-lived assets, including goodwill and intangible assets, and the measurement of right-of-use assets and lease liabilities, stock-based compensation expense, accrued expenses, income taxes, gross to net revenue reserves, inventory reserved, and the assessment of the Company's ability to fund its operations for at least the next twelve months from the date of issuance of these financial statements.
Inventory	Inventory Inventories are stated at the lower of cost or net realizable value under the first-expired, first-out ("FEFO") methodology. Given human gene therapy products are a new and novel category of therapeutics and future economic benefit is not probable until regulatory approval for the product has been obtained, the Company has only considered inventory for capitalization upon and after regulatory approval. Manufacturing costs incurred prior to regulatory approval for pre-launch inventory that did not qualify for capitalization and clinical manufacturing costs were charged to research and development expense in the Company’s consolidated statements of operations and comprehensive loss as costs were incurred. Additionally, inventory that initially qualifies for capitalization but that may ultimately be used for the production of clinical drug product is expensed as research and development expense when it has been designated for the manufacture of clinical drug product. Inventory consists of cell banks, plasmids, lentiviral vector ("LVV"), other materials and compounds sourced from third party suppliers and utilized in the manufacturing process, and drug product, which has been produced for the treatment of specific patients, that are owned by the Company. Management periodically reviews inventories for excess or obsolescence, considering factors such as sales forecasts compared to quantities on hand and firm purchase commitments as well as remaining shelf life of on hand inventories. The Company writes-down its inventory that is obsolete or otherwise unmarketable to its estimated net realizable value in the period in which the impairment is first identified. Any such adjustments are included as a component of cost of goods sold within cost of product revenue on the Company’s consolidated statements of operations and comprehensive loss.
Revenue recognition	Revenue recognition Under ASC Topic 606, Revenue from Contracts with Customers (“Topic 606”), an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer. Once a contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The Company assesses whether each promised good or service is distinct for the purpose of identifying the performance obligations in the contract. This assessment involves subjective determinations and requires management to make judgments about the individual promised goods or services and whether such are separable from the other aspects of the contractual relationship. Promised goods and services are considered distinct provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (that is, the good or service is capable of being distinct) and (ii) the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (that is, the promise to transfer the good or service is distinct within the context of the contract). The transaction price is then determined and allocated to the identified performance obligations in proportion to their standalone selling prices (“SSP”) on a relative SSP basis. SSP is determined at contract inception and is not updated to reflect changes between contract inception and when the performance obligations are satisfied. If the consideration promised in a contract includes a variable amount, the Company estimates the amount of consideration to which it will be entitled in exchange for transferring the promised goods or services to a customer. The Company determines the amount of variable consideration by using the expected value method or the most likely amount method. The Company includes the unconstrained amount of estimated variable consideration in the transaction price. The amount included in the transaction price is constrained to the amount for which it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates the estimated variable consideration included in the transaction price 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 in the period of adjustment. If a license arrangement includes development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached 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, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. In determining the transaction price, the Company adjusts consideration for the effects of the time value of money if the timing of payments provides the Company with a significant benefit of financing. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The Company assessed each of its revenue generating arrangements in order to determine whether a significant financing component exists and concluded that a significant financing component does not exist in any of its arrangements. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) each performance obligation is satisfied, at a point in time. The Company recognizes revenue within the following financial statement captions: Product revenue, net The Company recognizes product revenue, net in accordance with Topic 606. Product revenue, net represents sales of ZYNTEGLO and SKYSONA. In 2022, the Company received approval of ZYNTEGLO and SKYSONA from the FDA. The amount of revenue recognized by the Company is equal to the amount of consideration that is expected to be received from the sale of product to its customers. The Company has Specialty Distributors ("SD") and Specialty Pharmacies ("SP") that deliver product to the Qualified Treatment Centers ("QTC"). Revenue is only recognized when the performance obligation is satisfied. The Company will recognize revenue upon infusion to the patient. To determine whether a significant reversal will occur in future periods, the Company will assess both the likelihood and magnitude of any such potential reversal of revenue. Other revenue In 2021, the Company entered into a grant agreement with the Bill and Melinda Gates Foundation. The Company recognizes grant revenue in accordance with ASC 958-605, Revenue Recognition Not-for-Profit Entities , when qualifying costs are incurred and barriers to restriction have been overcome. When grant funds are received after costs have been incurred, the Company records revenue and a corresponding grant receivable. Cash received from grants in advance of incurring qualifying costs is recorded as deferred revenue and recognized as revenue when qualifying costs are incurred. In 2023, the Company ceased further research work and is in the process of winding down such collaboration.
Recent accounting pronouncements	Recent accounting pronouncements During the periods presented, the Company was not required to adopt any recently issued accounting standards. The Company does not expect any recently issued accounting standards to have a material impact on its financial statements.

Marketable securities (Tables)

Marketable securities (Tables)	3 Months Ended
	Mar. 31, 2023
Investments, Debt and Equity Securities [Abstract]
Summary of Marketable Securities Held	The following table summarizes the marketable securities held at March 31, 2023 and December 31, 2022 (in thousands): Description Amortized cost / Cost Unrealized gains Unrealized losses Fair value March 31, 2023 U.S. government agency securities and treasuries $ 79,600 $ 4 $ (883) $ 78,721 Corporate bonds 500 — (9) 491 Total $ 80,100 $ 4 $ (892) $ 79,212 December 31, 2022 U.S. government agency securities and treasuries $ 67,970 $ — $ (1,733) $ 66,237 Corporate bonds 2,524 — (26) 2,498 Total $ 70,494 $ — $ (1,759) $ 68,735

Fair value measurements (Tables

Fair value measurements (Tables)	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Recorded Amount of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table sets forth the Company’s assets and liabilities that are measured at fair value on a recurring basis as of March 31, 2023 and December 31, 2022 (in thousands): Description Total Quoted prices in active markets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) March 31, 2023 Assets: Cash and cash equivalents $ 239,045 $ 239,045 $ — $ — Marketable securities: U.S. government agency securities and treasuries 78,721 — 78,721 — Corporate bonds 491 — 491 — Total $ 318,257 $ 239,045 $ 79,212 $ — December 31, 2022 Assets: Cash and cash equivalents $ 113,006 $ 113,006 $ — $ — Marketable securities: U.S. government agency securities and treasuries 66,237 — 66,237 — Corporate bonds 2,498 — 2,498 — Total $ 181,741 $ 113,006 $ 68,735 $ —
Summary of Available-for-sale Debt Securities in Continuous Unrealized Loss Position	The following table summarizes available-for-sale debt securities in a continuous unrealized loss position for less than and greater than twelve months, and for which an allowance for credit losses has not been recorded at March 31, 2023 and December 31, 2022 (in thousands): Less than 12 months 12 months or greater Total Description Fair value Unrealized losses Fair value Unrealized losses Fair value Unrealized losses March 31, 2023 U.S. government agency securities $ 9,767 $ — $ 59,099 $ (883) $ 68,866 $ (883) Corporate bonds — — 491 (9) 491 (9) Total $ 9,767 $ — $ 59,590 $ (892) $ 69,357 $ (892) December 31, 2022 U.S. government agency securities $ — $ — $ 66,237 $ (1,733) $ 66,237 $ (1,733) Corporate bonds — — 2,498 (26) 2,498 (26) Total $ — $ — $ 68,735 $ (1,759) $ 68,735 $ (1,759)

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2023
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	Inventory, net, consists of the following (in thousands): As of March 31, 2023 As of December 31, 2022 Raw materials $ — $ — Work in progress 3,029 — Finished goods 780 — Inventory $ 3,809 $ —

Property, plant and equipment_2

Property, plant and equipment, net (Tables)	3 Months Ended
	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment Net	Property, plant and equipment, net, consists of the following (in thousands): As of March 31, 2023 As of December 31, 2022 Laboratory equipment $ 22,835 $ 25,092 Computer equipment and software 1,861 1,854 Office equipment 4,510 4,348 Construction-in-progress 80 — Total property, plant and equipment 29,286 31,294 Less accumulated depreciation and amortization (20,568) (21,932) Property, plant and equipment, net $ 8,718 $ 9,362

Accrued expenses and other cu_2

Accrued expenses and other current liabilities (Tables)	3 Months Ended
	Mar. 31, 2023
Payables and Accruals [Abstract]
Summary of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): As of March 31, 2023 As of December 31, 2022 Accrued manufacturing costs $ 5,586 $ 7,199 Accrued goods and services 9,655 8,134 Accrued clinical and contract research organization costs 14,005 12,368 Accrued employee compensation 9,291 20,095 Accrued professional fees 1,599 1,939 Deferred revenue, current portion 4,217 1,502 Other 941 748 Total accrued expenses and other current liabilities $ 45,294 $ 51,985

Stock-based compensation (Table

Stock-based compensation (Tables)	3 Months Ended
	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Stock-Based Compensation Expense by Award Type	Stock-based compensation expense recognized by award type is included within the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): For the three months ended March 31, 2023 2022 Stock options $ 1,723 $ 5,260 Restricted stock units 3,668 7,034 Employee stock purchase plan and other — 96 $ 5,391 $ 12,390
Schedule of Stock-Based Compensation Expense by Classification	Stock-based compensation expense by classification included within the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): For the three months ended March 31, 2023 2022 Cost of Product Revenue $ 103 $ — Selling, general and administrative 2,361 5,835 Research and development 2,927 6,555 $ 5,391 $ 12,390
Summary of Stock Option Activity Under Plan	The following table summarizes the stock option activity under the Company’s equity award plans and have been adjusted to reflect the effects of the November 2021 separation of our severe genetic disease and oncology programs into two separate, publicly traded companies: Shares (in thousands) Weighted- average exercise price per share Outstanding at December 31, 2022 2,668 $ 24.38 Granted 1,642 $ 5.26 Exercised (3) $ 2.74 Canceled or forfeited (73) $ 36.23 Outstanding at March 31, 2023 4,234 $ 16.77 Exercisable at March 31, 2023 1,313 $ 36.51 Vested and expected to vest at March 31, 2023 4,234 $ 16.77
Summary of Restricted Common Stock Awards	The following table summarizes the restricted stock unit activity under the Company’s equity award plans: Shares Weighted- Unvested at December 31, 2022 2,415 $ 11.44 Granted 2,503 $ 5.20 Vested (326) $ 20.01 Forfeited (107) $ 7.56 Unvested at March 31, 2023 4,485 $ 7.70

Net loss per share (Tables)

Net loss per share (Tables)	3 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
Basic and diluted EPS	Basic and diluted EPS for the three months ended March 31, 2023 and 2022 were calculated as follows (in thousands except per share data): For the three months ended 2023 2022 Numerator: Net Income 21,240 (122,152) (1) Denominator: Basic weighted-average common shares outstanding 102,920 Effect of dilutive securities 383 Diluted weighted-average common shares outstanding 103,303 Basic EPS $ 0.21 Diluted EPS $ 0.21

Description of the business (De

Description of the business (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	Jan. 31, 2023	Apr. 30, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022	Dec. 31, 2022
Subsequent Event [Line Items]
Gain from sale of priority review voucher, net	$ 92,900		$ 92,930	$ 0
Shares of common stock sold (in shares)			23
Offering costs			$ 130,500
Cash, cash equivalents and marketable securities			318,300
Accumulated deficit			3,965,263			$ 3,986,503
Net income (loss)			(21,240)	122,152
Net cash used in operating activities			$ 86,638	$ 125,296
Public Stock Offering
Subsequent Event [Line Items]
Shares of common stock sold (in shares)	23
Common stock price per share (in dollars per share)	$ 6
Proceeds from stock offering	$ 130,500
April 2022 Reduction
Subsequent Event [Line Items]
Plans to reduce workforce, as a percent		30%			30%

Basis of presentation, princi_3

Basis of presentation, principles of consolidation and significant accounting policies (Detail)	3 Months Ended
	Mar. 31, 2023 segment
Accounting Policies [Abstract]
Number of operating segments	1

Marketable securities (Detail)

Marketable securities (Detail) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Amortized cost / Cost
Marketable securities	$ 80,100,000	$ 70,494,000
Unrealized gains
Marketable securities	4,000	0
Unrealized losses
Marketable securities	(892,000)	(1,759,000)
Fair value
Marketable securities	79,212,000	68,735,000
Debt securities, available-for-sale, noncurrent	0	0
U.S. government agency securities and treasuries
Amortized cost / Cost
Debt securities	79,600,000	67,970,000
Unrealized gains
Debt securities	4,000	0
Unrealized losses
Debt securities	(883,000)	(1,733,000)
Fair value
Debt securities	78,721,000	66,237,000
Corporate bonds
Amortized cost / Cost
Debt securities	500,000	2,524,000
Unrealized gains
Debt securities	0	0
Unrealized losses
Debt securities	(9,000)	(26,000)
Fair value
Debt securities	$ 491,000	$ 2,498,000

Fair value measurements - Recor

Fair value measurements - Recorded Amount of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Marketable securities:	$ 79,212	$ 68,735
Fair Value, Measurements, Recurring
Assets:
Cash and cash equivalents	239,045	113,006
Total	318,257	181,741
Fair Value, Measurements, Recurring | U.S. government agency securities and treasuries
Assets:
Marketable securities:	78,721	66,237
Fair Value, Measurements, Recurring | Corporate bonds
Assets:
Marketable securities:	491	2,498
Fair Value, Measurements, Recurring | Quoted prices in active markets (Level 1)
Assets:
Cash and cash equivalents	239,045	113,006
Total	239,045	113,006
Fair Value, Measurements, Recurring | Quoted prices in active markets (Level 1) | U.S. government agency securities and treasuries
Assets:
Marketable securities:	0	0
Fair Value, Measurements, Recurring | Quoted prices in active markets (Level 1) | Corporate bonds
Assets:
Marketable securities:	0	0
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2)
Assets:
Cash and cash equivalents	0	0
Total	79,212	68,735
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) | U.S. government agency securities and treasuries
Assets:
Marketable securities:	78,721	66,237
Fair Value, Measurements, Recurring | Significant other observable inputs (Level 2) | Corporate bonds
Assets:
Marketable securities:	491	2,498
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3)
Assets:
Cash and cash equivalents	0	0
Total	0	0
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) | U.S. government agency securities and treasuries
Assets:
Marketable securities:	0	0
Fair Value, Measurements, Recurring | Significant unobservable inputs (Level 3) | Corporate bonds
Assets:
Marketable securities:	$ 0	$ 0

Fair value measurements - Narra

Fair value measurements - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Realized gain (loss) on available-for-sale securities	$ 0.1	$ 0
Interest receivable	0.6		$ 0.1
Interest receivable, write-offs	$ 0	$ 0

Fair value measurements - Sched

Fair value measurements - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair value
Less than 12 months	$ 9,767	$ 0
12 months or greater	59,590	68,735
Total	69,357	68,735
Unrealized losses
Less than 12 months	0	0
12 months or greater	(892)	(1,759)
Total	(892)	(1,759)
U.S. government agency securities and treasuries
Fair value
Less than 12 months	9,767	0
12 months or greater	59,099	66,237
Total	68,866	66,237
Unrealized losses
Less than 12 months	0	0
12 months or greater	(883)	(1,733)
Total	(883)	(1,733)
Corporate bonds
Fair value
Less than 12 months	0	0
12 months or greater	491	2,498
Total	491	2,498
Unrealized losses
Less than 12 months	0	0
12 months or greater	(9)	(26)
Total	$ (9)	$ (26)

Inventory (Details)

Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Raw materials	$ 0	$ 0
Work in progress	3,029	0
Finished goods	780	0
Inventory	$ 3,809	$ 0

Inventory - Narrative (Details)

Inventory - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Inventory Disclosure [Abstract]
Excess inventory reserve	$ 228	$ 7,519

Property, plant and equipment_3

Property, plant and equipment, net - Summary of Property, Plant and Equipment Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 29,286	$ 31,294
Less accumulated depreciation and amortization	(20,568)	(21,932)
Property, plant and equipment, net	8,718	9,362
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	22,835	25,092
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	1,861	1,854
Office equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	4,510	4,348
Construction-in-progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 80	$ 0

Accrued expenses and other cu_3

Accrued expenses and other current liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued manufacturing costs	$ 5,586	$ 7,199
Accrued goods and services	9,655	8,134
Accrued clinical and contract research organization costs	14,005	12,368
Accrued employee compensation	9,291	20,095
Accrued professional fees	1,599	1,939
Deferred revenue, current portion	4,217	1,502
Other	941	748
Total accrued expenses and other current liabilities	$ 45,294	$ 51,985

Commitments and contingencies (

Commitments and contingencies (Detail) $ in Millions	Mar. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Decrease in purchase commitments	$ 3.3

Stock-based compensation - Narr

Stock-based compensation - Narrative (Detail) - USD ($) shares in Thousands, $ in Thousands	1 Months Ended		3 Months Ended
	Jan. 31, 2023	Jan. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increased number of issuance of awards under the 2013 Plan (in shares)	3,300	2,800
Number of shares available for issuance (in shares)			5,900
Stock-based compensation expense			$ 5,391	$ 12,390
Amount capitalized			$ 500
Stock option share exercised (in shares)			3
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option share exercised (in shares)			100
Proceeds from exercise of stock options and ESPP contributions			$ 100
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			1,723	5,260
Employee stock purchase plan and other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 0	$ 96
Common shares reserved for future issuance (in shares)						200
Increase in shares authorized (in shares)					1,400
Employee stock purchase plan and other | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock issued under plan (in shares)			100	0

Stock-based compensation - Summ

Stock-based compensation - Summary of Stock-Based Compensation Expense by Award Type (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 5,391	$ 12,390
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,723	5,260
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3,668	7,034
Employee stock purchase plan and other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0	$ 96

Stock-based compensation - Sche

Stock-based compensation - Schedule of Stock-Based Compensation Expense by Classification (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 5,391	$ 12,390
Cost of Product Revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	103	0
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2,361	5,835
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,927	$ 6,555

Stock-based compensation - Su_2

Stock-based compensation - Summary of Stock Option Activity Under Plan (Detail) shares in Thousands	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Shares (in thousands)
Outstanding at beginning of period (in shares) | shares	2,668
Granted (in shares) | shares	1,642
Exercised (in shares) | shares	(3)
Canceled or forfeited (in shares) | shares	(73)
Outstanding at end of period (in shares) | shares	4,234
Exercisable at end of period (in shares) | shares	1,313
Vested and expected to vest at end of period (in shares) | shares	4,234
Weighted- average exercise price per share
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 24.38
Granted (in dollars per share) | $ / shares	5.26
Exercised (in dollars per share) | $ / shares	2.74
Canceled or forfeited (in dollars per share) | $ / shares	36.23
Outstanding at end of period (in dollars per share) | $ / shares	16.77
Exercisable at end of period (in dollars per share) | $ / shares	36.51
Vested and expected to vest at end of period (in dollars per share) | $ / shares	$ 16.77

Stock-based compensation - Su_3

Stock-based compensation - Summary of Restricted Stock Units (Detail) - Restricted stock units shares in Thousands	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Shares (in thousands)
Unvested balance at beginning of period (in shares) | shares	2,415
Granted (in shares) | shares	2,503
Vested (in shares) | shares	(326)
Forfeited (in shares) | shares	(107)
Unvested balance at end of period (in shares) | shares	4,485
Weighted- average grant date fair value
Unvested balance at beginning of period (in dollars per share) | $ / shares	$ 11.44
Granted (in dollars per share) | $ / shares	5.20
Vested (in dollars per share) | $ / shares	20.01
Forfeited (in dollars per share) | $ / shares	7.56
Unvested balance at end of period (in dollars per share) | $ / shares	$ 7.70

Income taxes (Details)

Income taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 0	$ 0

Net loss per share (Details)

Net loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net Income	$ 21,240	$ (122,152)
Denominator:
Basic weighted-average common shares outstanding (in shares)	102,920	73,688
Effect of dilutive securities (in shares)	383
Diluted weighted-average common shares outstanding (in shares)	103,303	0
Earnings Per Share, Basic And Diluted EPS
Basic EPS (In dollars per share)	$ 0.21	$ (1.66)
Diluted EPS (in dollars per share)	$ 0.21	$ 0
Outstanding stock options
Earnings Per Share, Basic And Diluted EPS
Common stock equivalents excluded from the calculation of diluted net loss per share (in shares)		5,600
Restricted stock units
Earnings Per Share, Basic And Diluted EPS
Common stock equivalents excluded from the calculation of diluted net loss per share (in shares)		4,100
Employee stock purchase plan and other
Earnings Per Share, Basic And Diluted EPS
Common stock equivalents excluded from the calculation of diluted net loss per share (in shares)		300

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) - April 2022 Reduction - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Apr. 30, 2022	Sep. 30, 2022
Restructuring Cost and Reserve [Line Items]
Plans to reduce workforce, as a percent	30%	30%
Payments for restructuring		$ 4.9