Scholar Rock Holding (SRRK) 10-Q7 May 242024 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 02, 2024
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-38501
Entity Registrant Name	SCHOLAR ROCK HOLDING CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-3750435
Entity Address, Address Line One	301 Binney Street, 3rd Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	857
Local Phone Number	259 3860
Title of 12(b) Security	Common Stock
Trading Symbol	SRRK
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		79,754,065
Entity Central Index Key	0001727196
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 91,979	$ 101,855
Marketable securities	146,453	178,083
Prepaid expenses and other current assets	8,501	8,256
Total current assets	246,933	288,194
Property and equipment, net	4,038	4,600
Operating lease right-of-use asset	9,805	11,417
Restricted cash	2,407	2,407
Other long-term assets	4,102	4,417
Total assets	267,285	311,035
Current liabilities:
Accounts payable	2,868	3,465
Accrued expenses	21,411	20,449
Operating lease liability	7,619	7,408
Short-term debt	5,501	1,334
Other current liabilities	107	85
Total current liabilities	37,506	32,741
Long-term portion of operating lease liability	2,412	4,392
Long-term debt	44,594	48,684
Total liabilities	84,512	85,817
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at March 31, 2024 and December 31, 2023; no shares issued and outstanding at March 31, 2024 and December 31, 2023
Common stock, $0.001 par value; 150,000,000 shares authorized; 79,744,654 and 75,979,495 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively	80	76
Additional paid-in capital	916,017	901,471
Accumulated other comprehensive income (loss)	(50)	92
Accumulated deficit	(733,274)	(676,421)
Total stockholders' equity	182,773	225,218
Total liabilities and stockholders' equity	$ 267,285	$ 311,035

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	79,744,654	75,979,495
Common stock, shares outstanding	79,744,654	75,979,495

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 43,094	$ 29,735
General and administrative	15,325	10,774
Total operating expenses	58,419	40,509
Loss from operations	(58,419)	(40,509)
Other income (expense), net	1,566	1,130
Net loss	$ (56,853)	$ (39,379)
Net loss per share, basic (in dollars per share)	$ (0.59)	$ (0.49)
Net loss per share, diluted (in dollars per share)	$ (0.59)	$ (0.49)
Weighted average common shares outstanding, basic (in shares)	95,892,601	79,610,059
Weighted average common shares outstanding, diluted (in shares)	95,892,601	79,610,059
Comprehensive loss:
Net loss	$ (56,853)	$ (39,379)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities	(142)	555
Total other comprehensive income (loss)	(142)	555
Comprehensive loss	$ (56,995)	$ (38,824)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at beginning at Dec. 31, 2022	$ 52	$ 771,699	$ (884)	$ (510,632)	$ 260,235
Balance at beginning (in shares) at Dec. 31, 2022	51,672,579
Increase (decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities			555		555
Sale of common shares, net of issuance costs		827			827
Sale of common shares, net of issuance costs (in shares)	68,696
Exercise of stock options		243			243
Exercise of stock options (in shares)	28,706
Issuance of common shares upon RSU vesting (in shares)	219,378
Equity-based compensation expense		6,170			6,170
Other		2			2
Net Income (Loss)				(39,379)	(39,379)
Balance at end at Mar. 31, 2023	$ 52	778,941	(329)	(550,011)	228,653
Balance at end (in shares) at Mar. 31, 2023	51,989,359
Balance at beginning at Dec. 31, 2023	$ 76	901,471	92	(676,421)	225,218
Balance at beginning (in shares) at Dec. 31, 2023	75,979,495
Increase (decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities			(142)		(142)
Exercise of stock options		280			280
Exercise of stock options (in shares)	47,293
Issuance of common shares upon RSU vesting (in shares)	360,373
Exercise of warrants	$ 4	6,102			6,106
Exercise of warrants (in shares)	3,357,493
Equity-based compensation expense		8,164			8,164
Net Income (Loss)				(56,853)	(56,853)
Balance at end at Mar. 31, 2024	$ 80	$ 916,017	$ (50)	$ (733,274)	$ 182,773
Balance at end (in shares) at Mar. 31, 2024	79,744,654

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (56,853)	$ (39,379)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	598	733
Amortization of debt discount and debt issuance costs	77	85
Equity-based compensation	8,164	6,170
Amortization/accretion of investment securities	(1,919)	(1,363)
Non-cash operating lease expense	1,612	1,812
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(384)	773
Other assets	315	66
Accounts payable	(610)	(274)
Accrued expenses	963	(9,591)
Operating lease liabilities	(1,769)	(1,984)
Other liabilities	21	(102)
Net cash used in operating activities	(49,785)	(43,054)
Cash flows from investing activities:
Purchases of property and equipment	(23)	(30)
Proceeds from sale of property and equipment		13
Purchases of marketable securities	(34,993)
Maturities of marketable securities	68,400	90,000
Net cash provided by (used in) investing activities	33,384	89,983
Cash flows from financing activities:
Proceeds from sale of common shares, net of issuance costs		827
Proceeds from pre-funded and common warrant exercises	6,106
Proceeds from stock option exercises	419	247
Other		2
Net cash provided by financing activities	6,525	1,076
Net (decrease)/increase in cash, cash equivalents and restricted cash	(9,876)	48,005
Cash, cash equivalents and restricted cash, beginning of period	104,262	105,773
Cash, cash equivalents and restricted cash, end of period	94,386	153,778
Supplemental disclosure of non-cash items:
Property and equipment purchases in accounts payable and accrued expenses	13
Supplemental cash flow information:
Cash paid for interest	$ 1,656	$ 1,491

Nature of the Business

Nature of the Business	3 Months Ended
Nature of the Business	Mar. 31, 2024
Nature of the Business and Basis of Presentation
Nature of the Business	1. Nature of the Business Scholar Rock Holding Corporation (the “Company”) is a late-stage biopharmaceutical company focused on the discovery, development, and delivery of innovative medicines for the treatment of serious diseases in which signaling by protein growth factors plays a fundamental role. As a global leader in transforming growth factor beta (“TGFβ”) superfamily biology, the Company’s novel understanding of the molecular mechanisms of growth factor activation enabled the development of a proprietary platform for the discovery and development of monoclonal antibodies that locally and selectively target the precursor, or latent, forms of growth factors. By targeting the signaling proteins at the cellular level and acting in the disease microenvironment, the Company believes that it may avoid the historical dose-limiting safety challenges associated with inhibiting growth factors for therapeutic effect. The Company’s first product candidate, apitegromab, is a highly selective, fully human, monoclonal antibody, with a unique mechanism of action that results in inhibition of the activation of the growth factor, myostatin, in skeletal muscle. Apitegromab is being developed as a potential first muscle-targeted therapy for the treatment of spinal muscular atrophy (“SMA”). The Company is conducting SAPPHIRE, a pivotal Phase 3 clinical trial to evaluate the efficacy and safety of apitegromab in patients with nonambulatory Type 2 and Type 3 SMA. In 2023, the Company completed enrollment for the Phase 3 SAPPHIRE trial and announced data from the Phase 2 TOPAZ trial extension period evaluating patient outcomes at 36 months of treatment with apitegromab. The U.S. Food and Drug Administration (“FDA”) granted Fast Track designation, Rare Pediatric Disease designation and Orphan Drug designation to apitegromab for the treatment of SMA in May 2021, August 2020 and March 2018, respectively. The European Medicines Agency (“EMA”) granted Priority Medicine (“PRIME”) designation in March 2021 and the European Commission (“EC”) granted Orphan Medicinal Product designation in December 2018 to apitegromab for the treatment of SMA. In October 2023, the Company announced plans to expand into cardiometabolic disorders and advance its anti-myostatin program with SRK-439, a novel, fully human anti-myostatin monoclonal antibody, for evaluation in cardiometabolic disorders, including obesity, towards a potential investigational new drug (“IND”) submission in 2025. To inform the development of SRK-439, the Company plans to initiate a Phase 2 proof-of-concept trial of apitegromab in combination with a GLP-1-receptor agonist in 2024. The Company’s second product candidate, SRK-181, a highly selective inhibitor of the activation of latent transforming growth factor beta (“TGFβ”), is being developed for the treatment of cancers that are resistant to checkpoint inhibitor (“CPI”) therapies, such as anti-PD-1 or anti-PD-L1 antibody therapies (referred to together as anti-PD-(L)1 antibody therapies). SRK-181 is being evaluated in the Company’s Phase 1 DRAGON proof-of-concept clinical trial in patients with locally advanced or metastatic solid tumors that exhibit resistance to anti-PD-(L)1 antibody therapies. The Phase 1 DRAGON trial completed enrollment in December 2023 and continues to treat patients who remain on study. This two-part clinical trial consists of a dose escalation portion (Part A) and a dose expansion evaluating SRK-181 in combination with an approved anti-PD- (L)1 antibody therapy (Part B). Part B includes the following active cohorts: urothelial carcinoma, cutaneous melanoma, non-small cell lung cancer, clear cell renal cell carcinoma, and head and neck squamous cell carcinoma. Safety, efficacy and biomarker data were presented in November 2023 at the Society for Immunotherapy of Cancer 38th Annual Meeting. Additionally, the Company continues to create a pipeline of product candidates to deliver novel therapies to underserved patients suffering from a wide range of serious diseases, including neuromuscular disorders, cardiometabolic disorders, cancer, fibrosis, and iron-restricted anemia. The Company was originally formed in May 2012. Its principal offices are in Cambridge, Massachusetts. Since its inception, the Company’s operations have focused on research and development of monoclonal antibodies that selectively inhibit activation of growth factors for therapeutic effect, as well as establishing the Company’s intellectual property portfolio and performing research and development activities. The Company has primarily financed its operations through various equity financings, as well as research and development collaboration agreements and the Company’s debt facility (Note 10). Revenue generation activities have been limited to two collaborations, both containing research services and the issuance of a license. The first agreement, executed in 2013, was with Janssen Biotech, Inc. (“Janssen”), a subsidiary of Johnson & Johnson and was terminated in July 2022. The second agreement, the Gilead Collaboration Agreement with Gilead Sciences, Inc. (“Gilead”), was in effect between December 2018 and January 2022. No revenues have been recorded from the sale of any commercial product. The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology and regulatory approval and market acceptance of the Company’s product candidates. The Company anticipates that it will continue to incur significant operating losses for the next several years as it continues to develop its product candidates. The Company believes that its existing cash, cash equivalents, and marketable securities at March 31, 2024 will be sufficient to allow the Company to fund its current operations through at least a period of one year after the date these financial statements are issued.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2024
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Summary of Significant Accounting Policies The significant accounting policies used in preparation of the unaudited consolidated financial statements are described in the Company’s audited consolidated financial statements as of and for the year ended December 31, 2023, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K. There have been no material changes to the significant accounting policies previously disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023. Cash, Cash Equivalents and Restricted Cash The following table reconciles cash, cash equivalents and restricted cash per the balance sheet to the statement of cash flows (in thousands): As of March 31, 2024 2023 Cash and cash equivalents $ 91,979 $ 151,280 Restricted cash 2,407 2,498 $ 94,386 $ 153,778 Unaudited Interim Financial Information The consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The unaudited consolidated financial statements include the accounts of Scholar Rock Holding Corporation and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and judgments that may affect the reported amounts of assets and liabilities and related disclosures of contingent assets and liabilities at the date of the financial statements and the related reporting of revenues and expenses during the reporting period. Management bases its estimates on historical experience and on various assumptions that are believed to be reasonable under the circumstances. Actual results could differ from those estimates. Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. The standard requires disclosure of incremental segment information on an annual and interim basis and allows for multiple measures of a segment’s profit or loss provided that one of those measures is consistent with GAAP. The amendments in this update do not change how a public company identifies its operating segments, aggregates those operating segments, or applies the quantitative thresholds to determine its reportable segments, but rather requires public entities to provide in interim periods all disclosures about a reporting segment’s profit or loss and assets that are currently required annually. ASU 2023-07 becomes effective for the annual period starting on January 1, 2024, and for interim periods starting on January 1, 2025. The option for early adoption is permitted, however, the Company has decided not to early adopt, does not anticipate a material impact to its net financial position, and is still evaluating the impact on its disclosures in future years as a result of the adoption of ASU 2023-07. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the transparency of income tax disclosures to provide information to investors to better assess how a company’s operations and related tax risks, tax planning and operational opportunities affect its tax rate and prospects for future cash flows. This requires public entities to disclose additional categories in the rate reconciliation regarding federal and state income taxes, and provide more details surrounding reconciling items if a quantitative threshold is met. The effective date for public companies is for annual periods starting on January 1, 2025. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance, however, the Company has decided not to early adopt, does not anticipate a material impact to its net financial position, and is still evaluating the impact on its disclosures will be in future years as a result of the adoption of ASU 2023-09.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	3 Months Ended
Fair Value of Financial Assets and Liabilities	Mar. 31, 2024
Fair Value of Financial Assets and Liabilities
Fair Value of Financial Assets and Liabilities	3. Fair Value of Financial Assets and Liabilities The following tables summarize the assets and liabilities measured at fair value on a recurring basis at March 31, 2024 and December 31, 2023 (in thousands): Fair Value Measurements at March 31, 2024 Total Level 1 Level 2 Level 3 Assets: Money market funds, included in cash and cash equivalents $ 70,144 $ 70,144 $ — $ — U.S. treasury obligations, included in cash and cash equivalents 14,976 14,976 — — Marketable securities: U.S. treasury obligations and government agency securities 146,453 146,453 — — Total assets $ 231,573 $ 231,573 $ — $ — Fair Value Measurements at December 31, 2023 Total Level 1 Level 2 Level 3 Assets: Money market funds, included in cash and cash equivalents $ 61,764 $ 61,764 $ — $ — U.S. treasury obligations, included in cash and cash equivalents 30,765 30,765 — — Marketable securities: U.S. treasury obligations and government agency securities 178,083 178,083 — — Total assets $ 270,612 $ 270,612 $ — $ — Cash, cash equivalents and marketable securities are Level 1 assets and include investments in money market funds and U.S. treasury obligations and government agency securities that are valued using quoted market prices. Accordingly, money market funds and government funds are categorized as Level 1 as of March 31, 2024 and December 31, 2023. There were no transfers of assets between fair value measurement levels during the three months ended March 31, 2024 or 2023. The carrying amounts reflected in the balance sheets for prepaid expenses and other current assets, accounts payable, and accrued expenses approximate their fair values at March 31, 2024 and December 31, 2023, due to their short-term nature. The Company believes the terms of its debt reflect current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company's debt approximates its fair value based on Level 3 of the fair value hierarchy.

Marketable Securities

Marketable Securities	3 Months Ended
Marketable Securities	Mar. 31, 2024
Marketable Securities
Marketable Securities	4. Marketable Securities The following table summarizes the Company’s investments as of March 31, 2024 (in thousands): Gross Amortized Unrealized Estimated Cost Gains Losses Fair Value Marketable securities available-for-sale: U.S. treasury obligations and government agency securities $ 146,503 $ 6 $ (56) $ 146,453 Total available-for-sale securities $ 146,503 $ 6 $ (56) $ 146,453 The following table summarizes the Company’s investments as of December 31, 2023 (in thousands): Gross Amortized Unrealized Estimated Cost Gains Losses Fair Value Marketable securities available-for-sale: U.S. treasury obligations and government agency securities $ 177,991 $ 93 $ (1) $ 178,083 Total available-for-sale securities $ 177,991 $ 93 $ (1) $ 178,083 The aggregate fair value of marketable securities with unrealized losses was $113.2 million and $11.9 million at March 31, 2024 and December 31, 2023, respectively. The Company believes that U.S. treasury obligations and government agency securities are subject to minimal credit risk. As a result, the Company did not record any charges for credit-related impairments for its available-for-sale securities for the three months ended March 31, 2024.

Prepaid Expenses and Other Asse

Prepaid Expenses and Other Assets	3 Months Ended
Prepaid Expenses and Other Assets	Mar. 31, 2024
Prepaid Expense and Other Assets
Prepaid Expenses and Other Assets	5. Prepaid Expenses and other Assets As of March 31, 2024 and December 31, 2023, prepaid expenses and other assets consist of the following (in thousands): As of March 31, December 31, 2024 2023 Prepaid external research and development expenses $ 4,471 $ 4,059 Prepaid other 2,607 2,486 Receivables 1,122 1,076 Prepaid insurance 301 635 $ 8,501 $ 8,256 As of March 31, 2024 and December 31, 2023, other long-term assets consist of the following (in thousands): As of March 31, December 31, 2024 2023 Prepaid external research and development expenses $ 3,701 $ 4,074 Prepaid other 374 312 Prepaid insurance 27 31 $ 4,102 $ 4,417

Accrued Expenses

Accrued Expenses	3 Months Ended
Accrued Expenses	Mar. 31, 2024
Accrued Expenses
Accrued Expenses	6. Accrued Expenses As of March 31, 2024 and December 31, 2023, accrued expenses consist of the following (in thousands): As of March 31, December 31, 2024 2023 Accrued external research and development expense $ 10,473 $ 6,825 Accrued payroll and related expenses 6,109 10,591 Accrued professional and consulting expense 3,915 2,267 Accrued other 914 766 $ 21,411 $ 20,449

Common Stock

Common Stock	3 Months Ended
Common Stock	Mar. 31, 2024
Common Stock.
Common Stock	7. Common Stock The Company has had a sales agreement in place during various time periods with Jefferies LLC (“Jefferies”) with respect to an at-the-market (“ATM”) offering program. Under this program, the Company is able to offer and sell, from time to time at its sole discretion, shares of its common stock through Jefferies as its sales agent. In an ATM offering, exchange-listed companies incrementally sell newly issued shares into the secondary trading market through a designated broker-dealer at prevailing market prices. The current ATM agreement, established in November 2022, allows for the sale of shares of common stock having an aggregate offering price of up to $100 million. As of March 31, 2024, the Company has sold 619,290 shares, generating net proceeds of $5.2 million, under the ATM program. No sales were made under the ATM program during the three months ended March 31, 2024. The Company has issued pre-funded warrants, as well as warrants as part of its financing activities. Both the pre-funded warrants and warrants meet the conditions for equity classification and are recorded as a component of stockholders’ equity within additional paid-in capital. In June 2022 and November 2020, the Company issued 25,510,205 and 2,179,487 pre-funded warrants, respectively. During the three months ended March 31, 2024, 2,526,833 of the Company’s pre-funded warrants were exercised. As of March 31, 2024, the Company has 17,008,164 pre-funded warrants outstanding. In June 2022, the Company also issued 10,459,181 warrants with an exercise price of $7.35 . During the three months ended March 31, 2024, 830,660 of the Company’s warrants were exercised. As of March 31, 2024, the Company has 9,157,496 warrants outstanding.

Equity-Based Compensation

Equity-Based Compensation	3 Months Ended
Equity-Based Compensation	Mar. 31, 2024
Equity-Based Compensation
Equity-Based Compensation	8. Equity-Based Compensation The Company recorded equity-based compensation expense related to all equity-based awards, which was allocated as follows in the consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023 (in thousands): Three Months Ended March 31, 2024 2023 Research and development expense $ 3,531 $ 2,645 General and administrative expense 4,633 3,525 $ 8,164 $ 6,170 The following table summarizes the Company’s unrecognized equity-based compensation expense as of March 31, 2024: As of March 31, 2024 Unrecognized Expense (in thousands) Weighted Average Remaining Period of Recognition (years) Restricted Stock Units $ 37,202 3.0 Stock Options 47,173 2.6 $ 84,375 Restricted Stock Units The following table summarizes the Company’s restricted stock unit activity for the current year: Weighted Average Grant Number of Units Date Fair Value Restricted stock units as of December 31, 2023 2,089,552 $ 11.92 Granted 1,392,076 $ 15.78 Vested (360,373) $ 16.54 Forfeited (31,566) $ 14.74 Restricted stock units as of March 31, 2024 3,089,689 $ 13.09 The total fair value of restricted stock units vested during the three months ended March 31, 2024 was $5.8 million. Stock Options The following table summarizes the Company’s stock option activity for the current year: Weighted Weighted Average Number of Average Remaining Aggregate Shares Exercise Price Contractual Term Intrinsic Value (in years) (in thousands) Outstanding as of December 31, 2023 7,300,953 $ 15.00 7.90 $ 52,299 Granted 1,856,108 $ 15.78 Exercised (47,293) $ 5.94 Cancelled (61,630) $ 20.97 Outstanding as of March 31, 2024 9,048,138 $ 15.17 8.12 $ 49,129 Options exercisable as of March 31, 2024 3,774,189 $ 17.79 6.83 $ 19,499 Using the Black-Scholes option pricing model, the weighted average fair value of options granted during the three months ended March 31, 2024 was $12.13. The following weighted average assumptions were used in determining the fair value of options granted in the three months ended March 31, 2024 and 2023: Three Months Ended March 31, 2024 2023 Risk-free interest rate 4.14 % 3.86 % Expected dividend yield 0.0 % 0.0 % Expected term (years to liquidity) 6.02 6.25 Expected volatility 91.39 % 90.17 %

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2024
Commitments and Contingencies
Commitments and Contingencies	9. Commitments and Contingencies Operating Lease In November 2019, the Company entered into a lease of office and laboratory space at 301 Binney Street in Cambridge, Massachusetts to be used as its new corporate headquarters. The expiration date of the lease is in August 2025 and the Company has the option to extend the term by two years. The base rent is $6.9 million per year, subject to an annual increase of 3.5%, and the Company was subject to a free-rent period through mid-August 2020. Variable lease payments include the Company’s allocated share of costs incurred and expenditures made by the landlord in the operation and management of the building. The lease included incentives of $14.1 million in the form of an allowance for tenant improvements related to the design and build out of the space. In connection with the lease, the Company has secured a letter of credit for $2.3 million which renews automatically each year. The lease commencement date, for accounting purposes, was reached in September 2020. Other information related to the Company’s lease is as follows (in thousands, except lease term and discount rate): For Three Months Ended March 31, 2024 Lease Cost: Operating lease cost $ 1,825 Variable lease cost 360 Total lease cost $ 2,185 For Three Months Ended March 31, 2024 Other information: Operating cash flows used for operating leases $ 1,981 Weighted average remaining lease term 1.4 Weighted average incremental borrowing rate 7.6 % Legal Proceedings The Company, from time to time, may be party to litigation arising in the ordinary course of its business. The Company was not subject to any material legal proceedings during the three months ended March 31, 2024 and 2023.

Debt

Debt	3 Months Ended
Debt	Mar. 31, 2024
Debt
Debt	10. Debt On October 16, 2020 (the “Closing Date”) the Company entered into a Loan and Security Agreement with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB”) for $50.0 million (the “Loan and Security Agreement”). Tranche 1 of $25.0 million was funded on the Closing Date. The Company had an additional $25.0 million in loan proceeds available under Tranche 2 which was funded in December 2021, in conjunction with the Company entering into the First Amendment to Loan and Security Agreement with Oxford and SVB. The Loan and Security Agreement was to mature on May 1, 2025 and required interest-only payments through November 2022, with principal payments to commence in December 2022. Pursuant to the Loan and Security Agreement, the Company was required to maintain cash in an SVB account equal to the lesser of 100% of the Company’s consolidated cash or 105% of the dollar amount of the outstanding debt. On November 10, 2022, the Company entered into the Second Amendment to Loan and Security Agreement (the “Amendment 2”) to increase the Company’s borrowing capacity under the Loan and Security Agreement to an amount up to $100.0 million, comprised of the original $50.0 million loan which remains outstanding and two additional $25.0 million tranches. The first $25.0 million tranche available under Amendment 2, was available at the Company’s discretion through December 2023 upon achievement of certain development and business performance milestones. The Company did not exercise this tranche. The second $25.0 million tranche available under Amendment 2, may be available upon the Company’s request, at Oxford and SVB’s discretion. Amendment 2 also extended the interest-only payment period for an additional 24 months through November 2024, with principal payments to commence in December 2024. The maturity of the loan was extended to November 2027. Effective upon Amendment 2, the interest rate on the unpaid principal is the greater of the Wall Street Journal prime rate plus 4.60% or 9.35% per annum. Prepayment is permitted and may include a pre-payment fee ranging from 0% - 3% (of the principal amount being prepaid), depending on when the prepayment is made. The Company is also required to make a final payment equal to 2% of the original principal amount. In conjunction with Amendment 2, the Company was required to pay $0.9 million for the accrued portion of the final payment on the previous outstanding balance. On March 10, 2023, SVB was closed by the California Department of Financial Protection and Innovation, which appointed the Federal Deposit Insurance Corporation (“FDIC”) as receiver. Afterward, the FDIC transferred all deposits of the former Silicon Valley Bank to Silicon Valley Bridge Bank, N.A., as operated by the FDIC. On March 27, 2023, Silicon Valley Bridge Bank was closed by the Office of the Comptroller of the Currency, and the FDIC was appointed as receiver. First Citizens Bank then entered into an agreement with the FDIC to purchase out of FDIC receivership substantially all loans and certain other assets and assume all customer deposits and certain other liabilities of Silicon Valley Bridge Bank. On March 27, 2023, Silicon Valley Bridge Bank and its U.S. branches began operating as Silicon Valley Bank, a division of First Citizens Bank. On April 18, 2023, the Company entered into Amendment 3 to the Loan and Security Agreement to amend certain provisions relating to the Company’s operating accounts.

Net Loss per Share

Net Loss per Share	3 Months Ended
Net Loss per Share	Mar. 31, 2024
Net Loss per Share
Net Loss per Share	11. Net Loss per Share The Company calculates basic net loss per share by dividing net loss by the weighted average number of common shares outstanding, excluding restricted common stock. The weighted average number of common shares used in the basic and diluted net loss per share calculation includes the pre-funded warrants issued in connection with the Company’s November 2020 and June 2022 follow-on offerings as the pre-funded warrants are exercisable at any time for nominal cash consideration. As of March 31, 2024, 10,681,528 pre-funded warrants have been exercised and 17,008,164 pre-funded warrants remain outstanding. The Company has generated a net loss in all periods presented, so the basic and diluted net loss per share are the same, as the inclusion of the potentially dilutive securities would be anti-dilutive. The following table sets forth the outstanding common stock equivalents, presented based on amounts outstanding at each period end, that have been excluded from the calculation of diluted net loss per share for the periods indicated because their inclusion would have been anti-dilutive: Three Months Ended March 31, 2024 2023 Restricted stock units 3,089,689 2,325,346 Stock options 9,048,138 7,539,205 Warrants 9,157,496 10,459,181 21,295,323 20,323,732

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2024
Summary of Significant Accounting Policies
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The following table reconciles cash, cash equivalents and restricted cash per the balance sheet to the statement of cash flows (in thousands): As of March 31, 2024 2023 Cash and cash equivalents $ 91,979 $ 151,280 Restricted cash 2,407 2,498 $ 94,386 $ 153,778
Unaudited Interim Financial Information	Unaudited Interim Financial Information The consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). The unaudited consolidated financial statements include the accounts of Scholar Rock Holding Corporation and its wholly owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and judgments that may affect the reported amounts of assets and liabilities and related disclosures of contingent assets and liabilities at the date of the financial statements and the related reporting of revenues and expenses during the reporting period. Management bases its estimates on historical experience and on various assumptions that are believed to be reasonable under the circumstances. Actual results could differ from those estimates.
Recently Adopted and Recently Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. The standard requires disclosure of incremental segment information on an annual and interim basis and allows for multiple measures of a segment’s profit or loss provided that one of those measures is consistent with GAAP. The amendments in this update do not change how a public company identifies its operating segments, aggregates those operating segments, or applies the quantitative thresholds to determine its reportable segments, but rather requires public entities to provide in interim periods all disclosures about a reporting segment’s profit or loss and assets that are currently required annually. ASU 2023-07 becomes effective for the annual period starting on January 1, 2024, and for interim periods starting on January 1, 2025. The option for early adoption is permitted, however, the Company has decided not to early adopt, does not anticipate a material impact to its net financial position, and is still evaluating the impact on its disclosures in future years as a result of the adoption of ASU 2023-07. In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which enhances the transparency of income tax disclosures to provide information to investors to better assess how a company’s operations and related tax risks, tax planning and operational opportunities affect its tax rate and prospects for future cash flows. This requires public entities to disclose additional categories in the rate reconciliation regarding federal and state income taxes, and provide more details surrounding reconciling items if a quantitative threshold is met. The effective date for public companies is for annual periods starting on January 1, 2025. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance, however, the Company has decided not to early adopt, does not anticipate a material impact to its net financial position, and is still evaluating the impact on its disclosures will be in future years as a result of the adoption of ASU 2023-09.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2024
Summary of Significant Accounting Policies
Schedule of reconciles of cash, cash equivalents and restricted cash	The following table reconciles cash, cash equivalents and restricted cash per the balance sheet to the statement of cash flows (in thousands): As of March 31, 2024 2023 Cash and cash equivalents $ 91,979 $ 151,280 Restricted cash 2,407 2,498 $ 94,386 $ 153,778

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	3 Months Ended
Fair Value of Financial Assets and Liabilities (Tables)	Mar. 31, 2024
Fair Value of Financial Assets and Liabilities
Schedule of summary of the assets and liabilities measured at fair value on a recurring basis	The following tables summarize the assets and liabilities measured at fair value on a recurring basis at March 31, 2024 and December 31, 2023 (in thousands): Fair Value Measurements at March 31, 2024 Total Level 1 Level 2 Level 3 Assets: Money market funds, included in cash and cash equivalents $ 70,144 $ 70,144 $ — $ — U.S. treasury obligations, included in cash and cash equivalents 14,976 14,976 — — Marketable securities: U.S. treasury obligations and government agency securities 146,453 146,453 — — Total assets $ 231,573 $ 231,573 $ — $ — Fair Value Measurements at December 31, 2023 Total Level 1 Level 2 Level 3 Assets: Money market funds, included in cash and cash equivalents $ 61,764 $ 61,764 $ — $ — U.S. treasury obligations, included in cash and cash equivalents 30,765 30,765 — — Marketable securities: U.S. treasury obligations and government agency securities 178,083 178,083 — — Total assets $ 270,612 $ 270,612 $ — $ —

Marketable Securities (Tables)

Marketable Securities (Tables)	3 Months Ended
Marketable Securities (Tables)	Mar. 31, 2024
Marketable Securities
Summary of investments	The following table summarizes the Company’s investments as of March 31, 2024 (in thousands): Gross Amortized Unrealized Estimated Cost Gains Losses Fair Value Marketable securities available-for-sale: U.S. treasury obligations and government agency securities $ 146,503 $ 6 $ (56) $ 146,453 Total available-for-sale securities $ 146,503 $ 6 $ (56) $ 146,453 The following table summarizes the Company’s investments as of December 31, 2023 (in thousands): Gross Amortized Unrealized Estimated Cost Gains Losses Fair Value Marketable securities available-for-sale: U.S. treasury obligations and government agency securities $ 177,991 $ 93 $ (1) $ 178,083 Total available-for-sale securities $ 177,991 $ 93 $ (1) $ 178,083

Prepaid Expenses and Other As_2

Prepaid Expenses and Other Assets (Tables)	3 Months Ended
Prepaid Expenses and Other Assets (Tables)	Mar. 31, 2024
Prepaid Expense and Other Assets
Schedule of prepaid expenses and other current assets	As of March 31, December 31, 2024 2023 Prepaid external research and development expenses $ 4,471 $ 4,059 Prepaid other 2,607 2,486 Receivables 1,122 1,076 Prepaid insurance 301 635 $ 8,501 $ 8,256
Schedule of other long-term assets	As of March 31, December 31, 2024 2023 Prepaid external research and development expenses $ 3,701 $ 4,074 Prepaid other 374 312 Prepaid insurance 27 31 $ 4,102 $ 4,417

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
Accrued Expenses (Tables)	Mar. 31, 2024
Accrued Expenses
Summary of accrued expenses	As of March 31, 2024 and December 31, 2023, accrued expenses consist of the following (in thousands): As of March 31, December 31, 2024 2023 Accrued external research and development expense $ 10,473 $ 6,825 Accrued payroll and related expenses 6,109 10,591 Accrued professional and consulting expense 3,915 2,267 Accrued other 914 766 $ 21,411 $ 20,449

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	3 Months Ended
Equity-Based Compensation (Tables)	Mar. 31, 2024
Equity-Based Compensation
Summary of allocation of equity-based compensation	The Company recorded equity-based compensation expense related to all equity-based awards, which was allocated as follows in the consolidated statements of operations and comprehensive loss for the three months ended March 31, 2024 and 2023 (in thousands): Three Months Ended March 31, 2024 2023 Research and development expense $ 3,531 $ 2,645 General and administrative expense 4,633 3,525 $ 8,164 $ 6,170
Summary of unrecognized equity-based compensation expense	As of March 31, 2024 Unrecognized Expense (in thousands) Weighted Average Remaining Period of Recognition (years) Restricted Stock Units $ 37,202 3.0 Stock Options 47,173 2.6 $ 84,375
Summary of stock activity	Weighted Average Grant Number of Units Date Fair Value Restricted stock units as of December 31, 2023 2,089,552 $ 11.92 Granted 1,392,076 $ 15.78 Vested (360,373) $ 16.54 Forfeited (31,566) $ 14.74 Restricted stock units as of March 31, 2024 3,089,689 $ 13.09
Summary of stock option activity	Weighted Weighted Average Number of Average Remaining Aggregate Shares Exercise Price Contractual Term Intrinsic Value (in years) (in thousands) Outstanding as of December 31, 2023 7,300,953 $ 15.00 7.90 $ 52,299 Granted 1,856,108 $ 15.78 Exercised (47,293) $ 5.94 Cancelled (61,630) $ 20.97 Outstanding as of March 31, 2024 9,048,138 $ 15.17 8.12 $ 49,129 Options exercisable as of March 31, 2024 3,774,189 $ 17.79 6.83 $ 19,499
Schedule of weighted average assumptions in fair value	Three Months Ended March 31, 2024 2023 Risk-free interest rate 4.14 % 3.86 % Expected dividend yield 0.0 % 0.0 % Expected term (years to liquidity) 6.02 6.25 Expected volatility 91.39 % 90.17 %

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
Commitments and Contingencies (Tables)	Mar. 31, 2024
Commitments and Contingencies
Summary of lease costs	Other information related to the Company’s lease is as follows (in thousands, except lease term and discount rate): For Three Months Ended March 31, 2024 Lease Cost: Operating lease cost $ 1,825 Variable lease cost 360 Total lease cost $ 2,185 For Three Months Ended March 31, 2024 Other information: Operating cash flows used for operating leases $ 1,981 Weighted average remaining lease term 1.4 Weighted average incremental borrowing rate 7.6 %

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
Net Loss per Share (Tables)	Mar. 31, 2024
Net Loss per Share
Summary of anti-dilutive securities	Three Months Ended March 31, 2024 2023 Restricted stock units 3,089,689 2,325,346 Stock options 9,048,138 7,539,205 Warrants 9,157,496 10,459,181 21,295,323 20,323,732

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Cash and cash equivalents and restricted cash
Cash and cash equivalents	$ 91,979	$ 101,855	$ 151,280
Restricted cash	2,407	2,407	2,498
Total	$ 94,386	$ 104,262	$ 153,778	$ 105,773

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Marketable securities:
U.S. Treasury obligations and government agency securities	$ 146,453	$ 178,083
Total assets	231,573	270,612
Money market funds
Assets:
Cash and cash equivalents	70,144	61,764
U.S. Treasury obligations
Assets:
Cash and cash equivalents	14,976	30,765
Level 1
Marketable securities:
U.S. Treasury obligations and government agency securities	146,453	178,083
Total assets	231,573	270,612
Level 1 \| Money market funds
Assets:
Cash and cash equivalents	70,144	61,764
Level 1 \| U.S. Treasury obligations
Assets:
Cash and cash equivalents	$ 14,976	$ 30,765

Marketable Securities - Summary

Marketable Securities - Summary of Investments (Details) $ in Thousands	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Marketable securities available-for-sale
Amortized Cost	$ 146,503	$ 177,991
Gross Unrealized Gains	6	93
Gross Unrealized Losses	(56)	(1)
Estimated Fair Value	146,453	178,083
Aggregate fair value of marketable securities with unrealized gains (losses) position for less than a year	$ 113,200	$ 11,900
Number of investments in an unrealized loss position for less than a year \| security	38	3
U.S. Treasury obligations
Marketable securities available-for-sale
Amortized Cost	$ 146,503	$ 177,991
Gross Unrealized Gains	6	93
Gross Unrealized Losses	(56)	(1)
Estimated Fair Value	$ 146,453	$ 178,083

Prepaid Expenses and Other As_3

Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Prepaid expenses and other current assets
Prepaid external research and development expense	$ 4,471	$ 4,059
Prepaid other	2,607	2,486
Receivables	1,122	1,076
Prepaid insurance	301	635
Total prepaid expenses and other current assets	8,501	8,256
Other long-term assets
Prepaid external research and development expense	3,701	4,074
Prepaid other	374	312
Prepaid insurance	27	31
Total other long-term assets	$ 4,102	$ 4,417

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accrued Expenses
Accrued external research and development expense	$ 10,473	$ 6,825
Accrued payroll and related expenses	6,109	10,591
Accrued professional and consulting expense	3,915	2,267
Accrued other	914	766
Accrued expenses	$ 21,411	$ 20,449

Common Stock - (Details)

Common Stock - (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024	Nov. 30, 2022	Jun. 30, 2022	Nov. 30, 2020
Pre-Funded Warrant
Equity
Warrant to purchase (in shares)			25,510,205	2,179,487
Exercise of warrants (in shares)	2,526,833
Outstanding warrants (in shares)	17,008,164
Pre-Funded Warrant \| Aggregate
Equity
Exercise of warrants (in shares)	10,681,528
Warrants
Equity
Warrant to purchase (in shares)			10,459,181
Exercise of warrants (in shares)	830,660
Outstanding warrants (in shares)	9,157,496
Warrant exercise price (in dollars per share)			$ 7.35
ATM Offering
Equity
Maximum aggregate offering price		$ 100
Sale of common shares, net of issuance costs (in shares)	0
ATM Offering \| Aggregate
Equity
Sale of shares	$ 5.2
Sale of common shares, net of issuance costs (in shares)	619,290

Equity-Based Compensation - Exp

Equity-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Equity-based compensation
Equity-based compensation expense	$ 8,164	$ 6,170
Research and development expense
Equity-based compensation
Equity-based compensation expense	3,531	2,645
General and administrative expense
Equity-based compensation
Equity-based compensation expense	$ 4,633	$ 3,525

Equity-Based Compensation - Unr

Equity-Based Compensation - Unrecognized Expense (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Equity-based compensation
Unrecognized Expense	$ 84,375
Restricted stock units
Equity-based compensation
Unrecognized Expense	$ 37,202
Weighted Average Remaining Period of Recognition	3 years
Employee Stock Option [Member]
Equity-based compensation
Unrecognized Expense	$ 47,173
Weighted Average Remaining Period of Recognition	2 years 7 months 6 days

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted stock (Details) - Restricted stock units $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares
Number of Shares/Units
Outstanding, beginning (in shares) \| shares	2,089,552
Granted (in shares) \| shares	1,392,076
Vested (in shares) \| shares	(360,373)
Forfeited (in shares) \| shares	(31,566)
Outstanding, end (in shares) \| shares	3,089,689
Weighted Average Grant Date Fair Value
Outstanding, beginning (in dollars per share) \| $ / shares	$ 11.92
Granted (in dollars per share) \| $ / shares	15.78
Vested (in dollars per share) \| $ / shares	16.54
Forfeited (in dollars per share) \| $ / shares	14.74
Outstanding, end (in dollars per share) \| $ / shares	$ 13.09
Fair value of non-option awards vested \| $	$ 5.8

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock Options (Details) - Employee Stock Option [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Number of Units
Outstanding, beginning (in shares)	7,300,953
Granted (in shares)	1,856,108
Exercised (in shares)	(47,293)
Cancelled (in shares)	(61,630)
Outstanding, end (in shares)	9,048,138	7,300,953
Options exercisable, end (in shares)	3,774,189
Weighted Average Exercise Price
Outstanding, beginning (in dollars per share)	$ 15
Granted (in dollars per share)	15.78
Exercised (in dollars per share)	5.94
Cancelled (in dollars per share)	20.97
Outstanding, end (in dollars per share)	15.17	$ 15
Options exercisable, end (in dollars per share)	$ 17.79
Stock options
Weighted average remaining contractual term	8 years 1 month 13 days	7 years 10 months 24 days
Weighted average remaining contractual term, exercisable	6 years 9 months 29 days
Aggregate intrinsic value, beginning	$ 52,299
Aggregate intrinsic value, end	49,129	$ 52,299
Aggregate intrinsic value, exercisable	$ 19,499
Weighted average grant date fair value (in dollars per share)	$ 12.13

Equity-Based Compensation - Ass

Equity-Based Compensation - Assumptions (Details) - Employee Stock Option [Member]	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Assumptions used in determining the fair value of options
Risk-free interest rate	4.14%	3.86%
Expected dividend yield	0%	0%
Expected term (years to liquidity)	6 years 7 days	6 years 3 months
Expected volatility	91.39%	90.17%

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Nov. 30, 2019	Mar. 31, 2024
Lease Cost:
Operating lease cost		$ 1,825
Variable lease cost		360
Total lease cost		2,185
Operating cash flows used for operating leases		$ 1,981
Weighted average remaining lease term		1 year 4 months 24 days
Weighted average incremental borrowing rate		7.60%
301 Binney St, Cambridge MA
Leased assets
Option to extend the term	true
Renewal term	2 years
Base rent	$ 6,900
Annual upward adjustment (as a percent)	3.50%
Incentive to lease	$ 14,100
Letter of credit	$ 2,300

Debt (Details)

Debt (Details) - Loan and Security Agreement - USD ($) $ in Millions			1 Months Ended
	Nov. 10, 2022	Oct. 16, 2020	Dec. 31, 2021
Debt
Line of credit maximum	$ 100	$ 50
Proceeds from credit facility		$ 25	$ 25
Interest only period	24 months
Final payment fee (as a percent)	2%
Repayments of debt	$ 0.9
Percentage of dollar value of company's consolidated cash		100%
Amount of cash required in a lender's account as a percentage of outstanding obligation (as a percent)		105%
Minimum
Debt
Prepayment penalty (as a percent)	0%
Maximum
Debt
Prepayment penalty (as a percent)	3%
Tranche One
Debt
Line of credit maximum	$ 25
Tranche Two
Debt
Line of credit maximum	$ 25
Wall Street Journal prime rate \| Minimum
Debt
Variable rate (as a percent)	4.60%
Wall Street Journal prime rate \| Maximum
Debt
Debt instrument, effective interest rate (as a percent)	9.35%

Net Loss per Share - Antidiluti

Net Loss per Share - Antidilutive (Details) - shares	3 Months Ended
Net Loss per Share - Antidilutive (Details) - shares	Mar. 31, 2024	Mar. 31, 2023
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	21,295,323	20,323,732
Pre-funded warrant
Anti-dilutive securities
Exercise of warrants (in shares)	2,526,833
Outstanding warrants (in shares)	17,008,164
Pre-funded warrant \| Aggregate
Anti-dilutive securities
Exercise of warrants (in shares)	10,681,528
Restricted stock units
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	3,089,689	2,325,346
Employee Stock Option [Member]
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	9,048,138	7,539,205
Warrants
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	9,157,496	10,459,181

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (56,853)	$ (39,379)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Trading Plans During the three months ended March 31, 2024, certain of our officers adopted contracts, instructions or written plans for the purchase or sale of our securities as noted below: Name and Title Type of Trading Arrangement Action Taken (Date of Action) Duration or End Date Aggregate Number of Securities to be Sold Description of Trading Arrangement Ted Myles, Chief Operating Officer and Chief Financial Officer Trading plan intended to satisfy the affirmative defense conditions of Securities Exchange Act Rule 10b5-1(c) Adoption (March 7, 2024) April 30, 2025 252,885(1) Sale of the Company's common stock pursuant to the terms of the plan Tracey Sacco, Chief Commercial Officer Trading plan intended to satisfy the affirmative defense conditions of Securities Exchange Act Rule 10b5-1(c) Adoption (March 19, 2024) June 18, 2025 30,000 Sale of the Company's common stock pursuant to the terms of the plan (1) These shares reflect the aggregate maximum number of Restricted Stock Units (“RSU”) prior to any non-discretionary sell-to-cover transactions in addition to other shares eligible to be sold pursuant to the plan. The Company has a non-discretionary sell-to-cover requirement to satisfy tax withholding obligations associated with RSU vesting for employees .
Ted Myles [Member]
Trading Arrangements, by Individual
Name	Ted Myles
Title	Chief Operating Officer and Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 7, 2024
Aggregate Available	252,885
Tracey Sacco [Member]
Trading Arrangements, by Individual
Name	Tracey Sacco
Title	Chief Commercial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 19, 2024