Scholar Rock Holding Corporation (SRRK)

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similar data prepared by market research firms and other third parties, industry, medical and general publications, government data, and similar sources, in some cases applying our own assumptions and analysis that may, in the future, prove not to have been accurate.

PART I

Item 1. Business

I. Overview

We are a global biopharmaceutical company dedicated to improving the lives of children and adults with spinal muscular atrophy (“SMA”) and additional rare, severe and debilitating neuromuscular diseases. As a leader in the biology of the transforming growth factor beta (“TGFβ”) superfamily, our 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. Based on our innovative, proprietary, and scalable technology platform, we are building a world-leading anti-myostatin pipeline. During 2025, we made significant progress in advancing our product candidates. We believe 2026 could be a transformational year for Scholar Rock as we anticipate the potential to become a commercial-stage biotech company.

Our lead pipeline product candidates include apitegromab, a subcutaneous formulation of apitegromab, and SRK-439.

Apitegromab is a novel, investigational, fully human monoclonal antibody that inhibits myostatin activation by selectively binding the pro- and latent forms of myostatin in skeletal muscle. Myostatin is a catabolic agent that functions as a negative regulator of muscle mass, therefore inhibition of myostatin results in increased muscle mass and strength. Apitegromab is in development for the treatment of people with SMA and for the treatment of people with facioscapulohumeral muscular dystrophy (“FSHD”).

Positive data from the successful Phase 3 SAPPHIRE study evaluating apitegromab in children and adults with SMA were reported in October 2024, and regulatory approvals are anticipated in the U.S. and Europe in 2026. Beyond SMA, a Phase 2 study evaluating apitegromab in patients with FSHD is expected to initiate in mid-2026. We see potential for apitegromab broadly in additional rare, severe, and debilitating neuromuscular diseases where muscle atrophy is a key component of disease pathogenesis, and we are actively exploring indications beyond SMA and FSHD.

In addition to the current intravenous (“IV”) formulation, we are developing a subcutaneous formulation of apitegromab. A Phase 1 study in healthy volunteers has been completed, demonstrating that subcutaneous (“SC”) apitegromab has favorable bioavailability and a comparable pharmacodynamic profile relative to IV administered apitegromab. Further development activities are ongoing, including planned FDA and EMA regulatory engagements.

Our clinical-stage pipeline also includes SRK-439, a novel, investigational, subcutaneously administered fully human anti-pro/latent myostatin antibody that has high inhibitory potency while maintaining selectivity towards myostatin. SRK-439 is being developed for the treatment of patients with rare, severe, and debilitating neuromuscular diseases. A Phase 1 study of SRK-439 in healthy volunteers is currently underway, with topline data anticipated in the second half of 2026.

Beyond our clinical-stage product candidates, our early-stage pipeline includes additional programs for the treatment of patients with rare, severe, and debilitating neuromuscular diseases.

As we focus our strategy on rare neuromuscular diseases, we are currently seeking partnerships for our additional programs. These programs include: SRK-181, a Phase 2-ready investigational inhibitor of latent TGFβ1 in development for the treatment of patients with solid tumors that are resistant to anti-PD-(L)1 antibody therapies; SRK-373, an investigational, highly selective inhibitor of the latent TGFβ1 isoform with selective activity in the fibrotic extracellular matrix, in preclinical development for the treatment of fibrotic diseases; and SRK-256, an investigational inhibitor of RGMc, or hemojuvelin, in preclinical development for the treatment of iron-restricted anemias. We are also seeking partners to further evaluate the potential for myostatin inhibition in combination with GLP-1 weight loss approaches

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following our positive Phase 2 EMBRAZE study, which demonstrated proof-of-concept in the ability of apitegromab to drive statistically significant preservation of lean mass during tirzepatide-induced weight loss.

During 2025, we made considerable progress advancing our pipeline and positioning Scholar Rock to become a global commercial-stage biotech company.

Key 2025 Highlights and Accomplishments:

●

Progressed U.S. and European regulatory activities for apitegromab for the treatment of children and adults with SMA. Scholar Rock submitted a BLA to the FDA in January 2025, received Priority Review designation in March 2025, and achieved acceptance of the EMA MAA in March 2025, representing significant regulatory milestones toward commercialization. The Company completed a constructive and collaborative in-person Type A meeting with the FDA in November 2025, following the receipt of a Complete Response Letter (CRL) from the FDA on September 22, 2025.

●

Transformed leadership team. Appointed eight-year Board Chairman, David Hallal, as Chief Executive Officer; Akshay Vaishnaw, M.D., Ph.D. as President of R&D; R. Keith Woods as Chief Operating Officer; Vikas Sinha as Chief Financial Officer; and Rebecca McLeod as Chief Brand Officer and U.S. General Manager, strengthening the Company’s leadership as it transitions toward a global commercial-stage organization.

●

Initiated U.S. and European build-out of commercial organization. Established a lean, experienced U.S. customer-facing team of approximately 50 professionals with deep expertise in neurology and rare disease. Commenced commercial build-out in Europe to support the planned European launch, starting with Germany.

●	Advanced industry-leading anti-myostatin pipeline. Progressed our strategic plan to build a robust pipeline of therapies for the treatment of people living with rare, severe, and debilitating neuromuscular diseases.

o	Initiated dosing in the Phase 2 OPAL study evaluating apitegromab in infants and toddlers under 2 years of age with SMA

o	Advanced preclinical development of apitegromab for FSHD and filed an Investigational New Drug (“IND”) application to support the initiation of a Phase 2 study

o	Completed a Phase 1 study of subcutaneous apitegromab in healthy volunteers

o	Initiated dosing in a Phase 1 study evaluating SRK-439 study in healthy volunteers

o	Continued the ongoing ONYX open-label extension study evaluating the long-term safety and efficacy of apitegromab in patients with SMA who participated in the TOPAZ and SAPPHIRE clinical trials

o	Completed the Phase 2 EMBRAZE study, demonstrating proof-of-concept in the ability of apitegromab to drive statistically significant preservation of lean mass during tirzepatide-induced weight loss

To achieve our mission to improve the lives of children and adults with SMA and additional rare, severe and debilitating neuromuscular diseases, we have assembled an experienced management team, board of directors, scientific founders, and technical leaders with extensive experience across drug discovery, development, and commercialization. Members of our team have held leadership roles across the biotechnology and pharmaceutical industry, including at Acceleron Pharma, Inc.; Alexion Pharmaceuticals; Alnylam Pharmaceuticals, Inc.; argenx US, Inc.; Celgene Corporation; Foundation Medicine, Inc.; and Novartis Pharmaceuticals. We were founded by internationally respected scientists, Drs. Timothy A. Springer and Leonard I. Zon of Harvard Medical School and Boston Children’s Hospital, whose foundational discoveries underpin our platform.

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II.Our Approach and Proprietary Platform

Scholar Rock’s innovative approach is rooted in our novel understanding of the molecular mechanisms of growth factor activation and signaling, and in our ability to discover and develop monoclonal antibodies that can inhibit the activation of a growth factor with an unprecedented degree of selectivity. Our proprietary platform is designed to generate highly selective antibodies that target a growth factor’s latent form, prior to its activation within the disease microenvironment, or tissue where it is localized.

Our approach of targeting the latent, precursor forms of growth factors is based on the breakthrough discovery by the laboratory of our cofounder, Timothy A. Springer, Ph.D. of Harvard Medical School and Boston Children’s Hospital.

Unlike many other proteins that are produced and secreted by cells in a mature, or active form, many growth factors are expressed by cells in a latent form. For example, TGFβ1 is produced by cells as a single protein that is enzymatically processed into two distinct and physically separated domains, the mature growth factor and the remaining portion of the original protein, referred to as the prodomain, which remain associated as part of a complex. This secreted complex is latent, or inactive, and must first be activated to carry out its normal function in a localized tissue or disease microenvironment. In a seminal peer-reviewed publication in 2011, Dr. Springer elucidated a new understanding of the mechanism of activation of the latent growth factor complex among members of the TGFβ superfamily by solving a high-resolution x-ray crystal structure of this latent form of TGFβ1 (as illustrated in the graphic below).

Structural representation of the latent form of TGFβ1 wherein the prodomain wraps around the growth factor domain

This research explained, at a molecular level, why the secreted form of TGFβ1 is inactive: the prodomain, though physically separated from the mature growth factor domain, forms a “cage” around the active form of TGFβ1, preventing receptor signaling until activation occurs. Only when the cage is “unlocked” by a precursor activation event can the growth factor be released and mediate its effects in the local microenvironment. Dr. Springer further hypothesized that this phenomenon likely holds true for most members of the TGFβ superfamily, though the exact nature of the activation event, such as integrin binding or enzymatic cleavage, may differ among members of the superfamily.

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Carrying this research forward, we confirmed the applicability of this approach in other members of the TGFβ superfamily, including myostatin. Similar to TGFβ, myostatin is initially expressed in an inactive precursor form known as promyostatin (as illustrated in the graphic below). Release of the active growth factor is regulated by two discrete protease cleavage events: promyostatin is converted to an inactive latent complex, then latent myostatin is cleaved to release active myostatin.

Importantly, while myostatin, as well as many other growth factors, are structurally similar, their cages are structurally diverse, and this provides the basis for our approach to improved selectivity.

We believe that there are several important advantages to our approach of targeting the latent forms of growth factors over conventional therapeutic approaches, which inhibit mature growth factors or their receptors systemically throughout the body:

●

Targeting the latent precursor enables intervention at the site of action within the diseased tissue microenvironment. Given that many growth factors act primarily within the microenvironment where they are activated, as opposed to exerting their effects systemically, we believe that prevention of activation is a preferred mode of action for achieving improved outcomes. In contrast, traditional approaches to targeting growth factor signaling are focused on inhibiting the growth factor after it has been activated and released systemically; and

●

Targeting the latent precursor allows heightened selectivity among structurally related growth factors, potentially limiting off-target effects. For example, two members of the TGFβ superfamily, myostatin and GDF11, are 90% identical in their growth factor domains. Therefore, many of the traditional inhibitors that target myostatin also inadvertently inhibit GDF11. Similarly, most of the known inhibitors of TGFβ are pan inhibitors, meaning that they do not distinguish among the three isoforms of TGFβ, namely, TGFβ1, TGFβ 2 and TGFβ3. Despite the sequence similarities of the active forms of these growth factors, their cages are structurally diverse. We have been able to harness this diversity to generate antibodies that specifically bind the inactive growth factor precursors and inhibit activation of a particular growth factor of interest, but not others that are closely related.

By selectively targeting precursor forms in the disease microenvironment, we believe we can interfere with the disease processes while minimizing the effects on the normal physiological processes potentially conferring a safety advantage.

We integrate these insights with sophisticated capabilities for protein expression, monoclonal antibody discovery and assay development to discover, design, optimize, and evaluate the characteristics of our monoclonal antibodies. Our proprietary platform is covered by a robust IP portfolio projected to expire well into the 2030s, excluding any patent term adjustments or extensions.

Using our innovative approach and proprietary platform, we are creating a pipeline of novel product candidates that selectively modulate growth factor activation implicated in rare, severe, and devastating neuromuscular diseases.

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III.Our Strategy

Our mission is to discover, develop, and deliver novel, life-transforming therapies to people suffering from rare, severe, and devastating neuromuscular diseases. To achieve our mission, our key long-term priorities include:

●	Maximize our opportunity to serve the rare neuromuscular disease community with our innovative anti-myostatin antibodies;

Loading financial statements...

Financial statements

data from SEC XBRL filings. Values are as-reported; restatements supersede originals. Values reported in .

From 10-Q filed 2026-05-07 (period ending 2026-03-31).

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our unaudited condensed consolidated financial statements and related notes appearing elsewhere in this Quarterly Report, and the audited financial information and the notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2025.

Our actual results and timing of certain events may differ materially from the results discussed, projected, anticipated, or indicated in any forward-looking statements. We caution you that forward-looking statements are not guarantees of future performance and that our actual results of operations, financial condition and liquidity, and the development of the industry in which we operate may differ materially from the forward-looking statements contained in this Quarterly Report. In addition, even if our results of operations, financial condition and liquidity, and the development of the industry in which we operate are consistent with the forward-looking statements contained in this Quarterly Report, they may not be predictive of results or developments in future periods.

The following information and any forward-looking statements should be considered in light of factors discussed elsewhere in this Quarterly Report, including those risks identified under Part II, Item 1A. Risk Factors.

We caution readers against placing undue reliance upon any such forward-looking statements, which speak only as of the date they are made. We disclaim any obligation, except as specifically required by law and the rules of the SEC, to publicly update or revise any such statements to reflect any change in our expectations or in events, conditions or circumstances on which any such statements may be based, or that may affect the likelihood that actual results will differ from those set forth in the forward-looking statements.

Overview

We are a global biopharmaceutical company dedicated to improving the lives of children and adults with spinal muscular atrophy (“SMA”) and additional rare, severe and debilitating neuromuscular diseases. As a leader in the biology of transforming growth factor beta (“TGFβ”) superfamily, our 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. Based on our innovative, proprietary, and scalable technology platform, we are building a world-leading anti-myostatin pipeline.

Our lead product candidates include apitegromab, a subcutaneous formulation of apitegromab, and SRK-439.

In October 2024, we announced positive top-line results in SAPPHIRE, a pivotal Phase 3 clinical trial to evaluate the efficacy and safety of apitegromab in patients with non-ambulatory Type 2 and Type 3 SMA (which is estimated to represent the majority of the current prevalent SMA patient population in the U.S. and Europe). The study achieved its primary endpoint. At the March 2025 Muscular Dystrophy Association Clinical & Scientific Conference, we presented additional data from secondary endpoint analyses in which apitegromab demonstrated a clinically meaningful and consistent benefit in motor function across pre-specified patient subgroups. We submitted a BLA to the FDA in January 2025 and the BLA was granted priority review designation. Priority review designation conveys that the FDA has determined that if apitegromab is approved, it could offer significant improvement in the safety or effectiveness of treatment of the serious condition of SMA. In September 2025, we received a CRL from the FDA related to observations identified during an FDA site inspection of a third-party fill-finish facility. The facility was issued a Form 483 by the FDA in July 2025 and the inspection classification of this facility is official action indicated (“OAI”). The observations were related to the facility and were not specific to apitegromab. The CRL did not cite any other approvability concerns, including apitegromab’s efficacy and safety data or the third-party drug substance manufacturer. In November 2025, we completed an in-person Type A meeting with the FDA that included participation of representatives from the third-party

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fill-finish facility. Also in November 2025, the third-party fill-finish facility received a Warning Letter from the FDA. We resubmitted the apitegromab BLA in March 2026 with two third-party fill-finish facilities included, which was accepted by the Agency with a September 30, 2026 Prescription Drug User Fee Act (“PDUFA”) action date. In March 2025 we submitted to the European Medicines Agency (“EMA”) and received validation of our marketing authorisation application (“MAA”) for apitegromab for the treatment of SMA. If apitegromab is approved by the FDA and/or the EC, we expect to initiate a commercial product launch in the applicable jurisdictions upon approval.

A Phase 2 study evaluating apitegromab in patients with FSHD is expected to initiate in mid-2026. We see potential for apitegromab broadly in additional rare, severe, and debilitating neuromuscular diseases where muscle atrophy is a key component of disease pathogenesis, and we are actively exploring indications beyond SMA and FSHD.

In addition to the current intravenous (“IV”) formulation, we are developing a subcutaneous (“SC”) formulation of apitegromab. A Phase 1 study in healthy volunteers has been completed and demonstrated that SC apitegromab has favorable bioavailability and a comparable pharmacodynamic profile relative to IV apitegromab. Further development activities are ongoing, including planned FDA and EMA regulatory engagements.

Beyond these clinical-stage product candidates, our early-stage pipeline includes additional preclinical programs intended for the treatment of patients with rare, severe, and debilitating neuromuscular diseases.

We have incurred significant operating losses since inception. Our net losses were $105.5 million for the three months ended March 31, 2026. As of March 31, 2026, we had an accumulated deficit of $1.4 billion. We expect to continue to incur significant expenses and operating losses for the foreseeable future in performing our ongoing activities, as we:

●	develop our commercialization capabilities to support product sales, marketing and distribution activities;

●	continue development activities for apitegromab in SMA, including the ONYX study, our Phase 2 OPAL study for SMA patients under two years of age and the associated drug supply;

●	explore and continue development activities for apitegromab in other neuromuscular disorders, including our planned Phase 2 FORGE clinical trial for apitegromab in FSHD;

●	continue research and development activities for our anti-myostatin program, including our Phase 1 clinical trial for SRK-439;

●	continue to discover, validate and develop additional product candidates through the use of our proprietary platform;

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●	maintain, expand and protect our intellectual property portfolio;

●	hire additional research, development, commercial and other business personnel; and

●	continue to build the global infrastructure to support our operations as a global public company.

To date, we have not generated any revenue from product sales. If we successfully obtain regulatory approval for apitegromab we may generate revenue in the future from product sales. In addition, if we obtain regulatory approval for apitegromab we have and expect to incur significant expenses related to developing our commercialization capabilities to support product sales, marketing and distribution activities.

Financial Operations Overview

Operating Expenses

Research and Development

Research and development expenses consist primarily of costs incurred for our research and development activities, including our product candidate discovery efforts, preclinical studies, manufacturing, and clinical trials under our research programs, which include:

●	employee-related expenses, including salaries, benefits and equity-based compensation expense for our research and development personnel;

●	expenses incurred under agreements with third parties that conduct research and development and preclinical activities on our behalf;

●	expenses incurred under agreements related to our clinical trials, including the costs for investigative sites and contract research organizations (“CROs”), that conduct our clinical trials;

●	manufacturing process development, manufacturing of clinical supplies, commercial drug supply prior to FDA approval and technology transfer expenses;

●	consulting and professional fees related to research and development activities;

●	costs of purchasing laboratory supplies and non-capital equipment used in our internal research and development activities;

●	costs related to compliance with clinical regulatory requirements; and

●	facility costs and other allocated expenses, which include expenses for rent and maintenance of facilities, insurance, depreciation and other supplies.

Research and development costs are expensed as incurred. Costs for certain activities are recognized based on an evaluation of the progress to completion of specific tasks. Nonrefundable advance payments for research and development goods and services to be received in the future from third parties are deferred and capitalized. The capitalized amounts are expensed as the related services are performed.

A significant portion of our research and development costs have been external costs, which we track on a program-by-program basis after a clinical product candidate has been identified. However, we do not allocate our internal research and development expenses, consisting primarily of employee-related costs, depreciation and other indirect costs, on a program-by-program basis as they are deployed across multiple projects.

Research and development activities are central to our business model. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials, as well as the associated clinical trial material requirements. We expect research and development costs for our product candidates to continue to be substantial for the foreseeable future as the development programs progress. However, we do not believe that it is possible at this time to accurately project total program-specific expenses through commercialization. There are numerous factors associated with the successful commercialization of any of our product candidates, including future trial design and various regulatory requirements, many of which cannot be determined with accuracy at this time based on our stage of

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development. Additionally, future commercial and regulatory factors beyond our control will impact our clinical development programs and plans.

The successful development of apitegromab, SRK-181, SRK-439, SRK-373, SRK-256 and any future product candidates is uncertain. Accordingly, at this time, we cannot reasonably estimate or know the nature, timing and estimated costs of the efforts that will be necessary to complete the remainder of the development of apitegromab, SRK-181, SRK-439, SRK-373, SRK-256 and any future product candidates. We are also unable to predict when, if ever, material net cash inflows will commence from the sale of our product candidates, if approved. This is due to the numerous risks and uncertainties associated with developing product candidates, including the uncertainty of:

●	the scope, progress, outcome and costs of our preclinical development activities, clinical trials and other research and development activities;

●	establishing an appropriate safety profile;

●	successful enrollment in and completion of clinical trials;

●	whether our product candidates show safety and efficacy in our clinical trials;

●	receipt of marketing approvals, if any, from applicable regulatory authorities;

●	establishing commercial manufacturing capabilities or making arrangements with third-party manufacturers;

●	obtaining and maintaining patent and trade secret protection and regulatory exclusivity for our product candidates;

●	significant and changing government regulation;

●	commercializing product candidates, if and when approved, whether alone or in collaboration with others; and

●	continued acceptable safety profile of the products following any regulatory approval.

Any of these variables, or other factors, with respect to the development of apitegromab, SRK-181, SRK-439, SRK-373, SRK-256 or any of our future product candidates could significantly change the costs and timing associated with the development of that product candidate.

General and Administrative

General and administrative expenses consist primarily of employee-related expenses, including salaries, benefits and equity-based compensation expenses for personnel in executive, finance, business development, investor relations, legal, information technology, human resources and commercial functions. Other significant general and administrative expenses include facility costs not otherwise included in research and development expenses, legal fees relating to patent and corporate matters and fees for accounting, consulting services, professional services and corporate expenses. We expect general and administrative expense to continue to be substantial as we continue to invest in building the infrastructure to support the commercialization of apitegromab.

Other Income (Expense), Net

Other income (expense), net consists primarily of interest income earned on our cash, cash equivalents and marketable securities, partially offset by interest expense incurred on our debt facility, including amortization of debt discount and debt issuance costs.

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Results of Operations

Comparison of the Three Months Ended March 31, 2026 and 2025

The following table summarizes our results of operations for the three months ended March 31, 2026 and 2025 (in thousands, except percentages):


		Three Months Ended March 31,					Change
		2026			2025		$		%
Operating expenses:
Research and development		$	51,814		$	48,678	$	3,136	6.4	%
General and administrative			50,202			28,412		21,790	76.7	%
Total operating expenses			102,016			77,090		24,926	32.3	%
Loss from operations			(102,016)			(77,090)		(24,926)	32.3	%
Other income (expense), net			(3,494)			2,367		(5,861)	(247.6)	%
Net loss		$	(105,510)		$	(74,723)	$	(30,787)	41.2	%

Operating Expenses

Research and Development

Research and development expense was $51.8 million and $48.7 million for the three months ended March 31, 2026 and 2025, respectively, an increase of $3.1 million or 6.4%. The following table summarizes our research and development expense for the three months ended March 31, 2026 and 2025 (in thousands, except percentages):


	Three Months Ended March 31,				Change
	2026		2025		$		%
External costs by program
Apitegromab	$	20,261	$	19,301	$	960	5.0	%
SRK-181		36		1,110		(1,074)	(96.8)	%
SRK-439		1,759		4,279		(2,520)	(58.9)	%
Other early programs and unallocated costs		1,210		1,455		(245)	(16.8)	%
Total external costs		23,266		26,145		(2,879)	(11.0)	%
Internal costs:
Employee compensation and benefits		23,682		18,110		5,572	30.8	%
Facility and other		4,866		4,423		443	10.0	%
Total internal costs		28,548		22,533		6,015	26.7	%
Total research and development expense	$	51,814	$	48,678	$	3,136	6.4	%

The increase in research and development expense was primarily attributable to the following:

●	A decrease in our external research and development costs of $2.9 million, which primarily consisted of:

$1.0 million increase in costs associated with apitegromab primarily due to an increase in drug supply manufacturing and the initiation of our Phase 2 OPAL trial in SMA patients under two years of age, partially offset by a decrease in clinical trial costs as our Phase 3 SAPPHIRE clinical trial is completed;

o	$1.1 million decrease in costs associated with SRK-181, as our Phase 1 DRAGON trial is completed; and

o	$2.5 million decrease in preclinical costs and manufacturing development for SRK-439.

●

A $6.0 million increase in internal research and development costs, which was primarily driven by an increase of $2.3 million in employee related costs, including salaries, bonus, benefits and payroll taxes, an increase of $2.5 million in non-cash equity-based compensation expense related to increased headcount and severance related costs of $0.8 million.

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Total research and development expenses are expected to continue to be substantial, driven by employee compensation costs and development costs associated with our manufacture of drug supply, as well as development of our clinical stage programs as we continue development activities for apitegromab in SMA, the conduct of ONYX, the conduct of our Phase 2 OPAL trial in SMA patients under the age of two, the conduct of our planned Phase 2 FORGE trial in FSHD patients, as well as costs associated with supporting our anti-myostatin program, including SRK-439. Additionally, we will continue to invest in our pipeline. We expect costs of our SRK-181 program to continue to decrease, as we completed the Phase 1 DRAGON clinical trial in June 2025.

General and Administrative

General and administrative expense was $50.2 million and $28.4 million for the three months ended March 31, 2026 and 2025, respectively, an increase of $21.8 million or 76.7%. The total increase was primarily driven by investments in infrastructure to support launch readiness for apitegromab, including an increase of approximately $11.5 million in employee-related costs including salaries, bonus, benefits and payroll taxes related to increased headcount, an increase of $2.3 million in non-cash equity-based compensation expense related to increased headcount, an increase of approximately $7.2 million in professional service fees and an increase of approximately $0.8 million in facility and other costs. The increase in headcount is partially associated with the hiring of our commercial and field-facing teams. We expect general and administrative expenses to continue to be substantial as we continue to invest in building the infrastructure to support the commercialization of apitegromab.

Other Income (Expense), Net

The change in other income (expense), net was primarily attributable to our loss on extinguishment of debt, partially offset by an increase in interest income earned due to higher average balances in our cash, cash equivalents and marketable securities.

Liquidity and Capital Resources

Sources of Liquidity

Since our inception, we have not generated any product revenue and have incurred significant operating losses and negative cash flows from our operations. We have funded our operations to date primarily with proceeds from the sale of our convertible preferred stock and units in private placements before our initial public offering (“IPO”), and issuance of our common stock through our IPO in 2018, to Gilead in an exempt private placement, through multiple secondary public offerings and through “at-the-market offerings” (“ATM”) sales, as well as payments from our research collaborations and the 2026 Loan Agreement (as defined below) entered into in February 2026 (see Note 11).

The following table provides information regarding our total cash, cash equivalents and marketable securities at March 31, 2026 and December 31, 2025 (in thousands):


		March 31,			December 31,
		2026			2025
Cash and cash equivalents		$	430,543		$	323,527
Marketable securities			49,401			44,036
Total cash, cash equivalents and marketable securities		$	479,944		$	367,563

During the three months ended March 31, 2026, our cash, cash equivalents and marketable securities balance increased by $112.4 million. The change was primarily due to proceeds from our debt facility, sales under our ATM program and the exercises of stock options, partially offset by cash used to operate our business, including payments related to, among other things, research and development and general and administrative expenses as we continued to invest in our product candidates and supported our internal research and development efforts and made interest payments on our debt.

Our current sales agreement with Jefferies, entered into in November 2022, allows for the sale of shares of our common stock from time to time in ATM offerings through Jefferies as the Company’s sales agent. During the three months ended March 31, 2026, we sold 2,576,299 shares of our common stock under the ATM program, generating net proceeds

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of $111.8 million. Of this amount, $13.8 million was received in April 2026 and was classified as a receivable and included in “Prepaid expenses and other current assets” in our consolidated balance sheets as of March 31, 2026.

In February 2025, we entered into an Amended and Restated Loan and Security Agreement with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB”) (such agreement, as amended, the “Existing Loan Agreement”) for up to $200 million of which $25.0 million from Tranche 1 was received in October 2020, $25.0 million from Tranche 2 was received in December 2021 and $50.0 million from Tranche 3 was received in September 2025, bringing the total outstanding balance under the Term Loans to $100.0 million. This debt facility was paid off in February 2026 (see Note 11).

In February 2026, we entered into a Financing Agreement (the “Financing Agreement”) and a Pledge and Security Agreement (the “Security Agreement,” together with the Financing Agreement, the “2026 Loan Agreement”) with certain funds managed by Blue Owl Capital Corporation (“Blue Owl”) for up to $350.0 million, of which $100.0 million of the initial term loan (the “Initial Term Loan”) was received in February 2026. In addition, the Financing Agreement includes an uncommitted incremental term loan facility that requires the consent of Blue Owl in an aggregate principal amount not to exceed $200.0 million. We used the proceeds of the Initial Term Loan upon the closing under the 2026 Loan Agreement to repay all outstanding obligations, totaling $103.7 million, under the Existing Loan Agreement with Oxford and upon such repayment, terminated the Existing Loan Agreement. The amount repaid by the Company included $100.0 million of outstanding indebtedness plus accrued and unpaid interest as of February 27, 2026 and fees. We recognized a loss on extinguishment of debt of $3.3 million in connection with the termination of the Existing Loan Agreement. As a result of the termination, all credit commitments under the Existing Loan Agreement were terminated and all security interests and guarantees executed in connection with the Existing Loan Agreement were released. On March 31, 2026, the Company received $100.0 million from the next available tranche under the 2026 Loan Agreement, bringing the outstanding balance to $200.0 million (see Note 11).

During the three months ended March 31, 2026, 6,804,082 of the Company’s pre-funded warrants were exercised. As of March 31, 2026, the Company had 10,558,065 pre-funded warrants outstanding.

During the three months ended March 31, 2026, none of the Company’s common warrants were exercised. As of March 31, 2026, the Company had 250,000 common warrants outstanding.

Cash Flows

The following table provides information regarding our cash flows for the three months ended March 31, 2026 and 2025 (in thousands):


	Three Months Ended March 31,
	2026		2025
Net cash used in operating activities	$	(82,101)	$	(78,675)
Net cash provided by (used in) investing activities		(5,335)		34,554
Net cash provided by financing activities		193,786		4,169
Net increase (decrease) in cash, cash equivalents and restricted cash	$	106,350	$	(39,952)

Net Cash Used in Operating Activities

Net cash used in operating activities was $82.1 million for the three months ended March 31, 2026, and consisted of our net loss of $105.5 million, partially offset by changes in our assets and liabilities of $0.1 million and non-cash adjustments of $23.3 million. The non-cash adjustments are primarily from equity-based compensation.

Net cash used in operating activities was $78.7 million for the three months ended March 31, 2025, and consisted of our net loss of $74.7 million and changes in our assets and liabilities of $17.6 million, partially offset by non-cash adjustments of $13.6 million. The non-cash adjustments are primarily from equity-based compensation.

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Net Cash Provided by Investing Activities

Net cash used in investing activities was $5.3 million for the three months ended March 31, 2026 compared to net cash provided by investing activities of $34.6 million for the three months ended March 31, 2025. Net cash provided by and used in investing activities for both periods was primarily associated with transactions involving our marketable securities.

Net Cash Provided by Financing Activities

Net cash provided by financing activities was $193.8 million for the three months ended March 31, 2026 compared to $4.2 million for the three months ended March 31, 2025. Net cash provided by financing activities for the three months ended March 31, 2026 was primarily attributable to $98.0 million in proceeds from the sale of common shares under our ATM program, $196.7 million in proceeds from our debt facility and $3.5 million from the exercise of stock options, partially offset by $103.1 million from the repayment of our Existing Loan Agreement with Oxford and $1.3 million of debt issuance costs related to our Financing Agreement with Blue Owl. Net cash provided by financing activities for the three months ended March 31, 2025 was primarily attributable to proceeds from the exercise of stock options and the proceeds from our debt refinancing, partially offset by the long-term debt extinguishment.

Funding Requirements

We expect our expenses to be substantial as we continue the research and development of apitegromab in SMA. In addition, we are seeking marketing approval for apitegromab, and we expect to incur significant commercialization expenses related to product sales, marketing, global manufacturing and distribution. We expect to continue to incur apitegromab development costs as we invest in trials to support other SMA patient populations, such as our Phase 2 OPAL clinical trial, and for programs in multiple other diseases beyond SMA where selective inhibition of myostatin activation may offer therapeutic benefit, such as our planned Phase 2 FORGE trial. We expect to incur costs to support our anti-myostatin program, including the close out activities for our Phase 2 EMBRAZE proof-of-concept trial of apitegromab and our Phase 1 trial for SRK-439. Additionally, we will support the development of our pipeline and any other preclinical programs. Furthermore, we expect to continue to incur costs associated with operating as a public company.

Based on our current operating model, we expect that our existing cash, cash equivalents and marketable securities will enable us to fund our operating expenses and capital expenditure requirements into 2027. However, we will require additional capital in order to complete clinical development and commercialization for each of our current programs. We have based this estimate on assumptions that may prove to be wrong, and we may use our available capital resources sooner than we currently expect. Our future capital requirements will depend on many factors, including:

●

the costs and timing of developing our product candidates and future product candidates, including costs associated with apitegromab in ONYX, our long-term extension study in SMA for patients from both the TOPAZ and SAPPHIRE studies, our Phase 2 OPAL trial in SMA patients under the age of two, our planned Phase 2 FORGE trial in FSHD patients, our Phase 1 trial of SRK-439 in healthy volunteers and the costs and timing of conducting future preclinical studies and clinical trials for SRK-373, SRK-256 or any other product candidates;

●	the costs of future manufacturing of apitegromab, SRK-181, SRK-439, SRK-373, SRK-256 and any other future product candidates;

●	the scope, progress, results and costs of discovery, preclinical development, laboratory testing and clinical trials for other potential product candidates we may develop, if any;

●	the costs of identifying and developing, or in-licensing or acquiring, additional product candidates and technologies;

●	the costs, timing and outcome of regulatory review of our product candidates;

●	our ability to establish and maintain collaborations on favorable terms, if at all;

●	the achievement of milestones or occurrence of other developments that trigger payments under any collaboration agreements, license agreements, or other agreements we might have at such time;

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●	the costs of seeking marketing approvals for apitegromab;

●	the costs and timing of future commercialization activities, including product sales, marketing, manufacturing and distribution for apitegromab, if approved;

●	the amount of revenue, if any, received from commercial sales of apitegromab, if approved;

●	the costs of preparing, filing and prosecuting patent applications, obtaining, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims;

●	our headcount growth and associated costs as we expand our global business operations and research and development activities;

●	the costs of supporting our global infrastructure and facilities, including equipment and physical infrastructure to support our research and development;

●	the costs of operating as a global public company; and

●	the impact of adverse global economic conditions on our business, including increased costs associated with global tariff policies, which may exacerbate the magnitude of the factors discussed above.

Identifying potential product candidates and conducting preclinical studies and clinical trials is a time-consuming, expensive and uncertain process that takes years to complete, and we may never generate the necessary data or results required to obtain marketing approval and achieve product sales. In addition, our product candidates, if approved, may not achieve commercial success. Accordingly, we will need to continue to rely on additional financing to achieve our business objectives. Adequate additional financing may not be available to us on acceptable terms, or at all.

Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. To the extent that we raise additional capital through the sale of equity or convertible debt securities, common stockholder ownership interests may be diluted, and the terms of these securities may include liquidation or other preferences that could adversely affect the rights of a common stockholder. Additional debt financing, if available, may involve agreements that include restrictive covenants that limit our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends, that could adversely impact our ability to conduct our business.

If we raise funds through collaborations, strategic alliances or licensing arrangements with third parties, we may have to relinquish valuable rights to our technologies, future revenue streams, research programs or product candidates or to grant licenses on terms that may not be favorable to us. Market volatility or other factors could also adversely impact our ability to access capital as and when needed. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Critical Accounting Estimates

This management’s discussion and analysis is based on our condensed consolidated financial statements, which have been prepared in accordance with U.S. generally accepted accounting principles. The preparation of these condensed consolidated financial statements requires us to make judgments and estimates that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in our condensed consolidated financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe to be reasonable under the circumstances, the results of which form the basis for making judgements about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions. On an ongoing basis, we evaluate our judgments and estimates in light of changes in circumstances, facts and experience. The effects of material revisions in estimates, if any, will be reflected in the condensed consolidated financial statements prospectively from the date of change in estimates. Our actual results may differ from these estimates under different assumptions or conditions.

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Held by

holders ( registered funds via N-PORT, institutional investors via 13F). Showing top by dollar value.

Holder	Type	ETF	MF	Position ($)	% of holder	Δ % of holder	Holder AUM

Recent insider activity

Last 90 days. Open-market trades (purchases & sales) by directors, officers, and 10%+ owners. 4 transactions across 4 insiders. Net: -63,491 shares, -$3,147,535.

Date	Insider	Role	Action	Shares	Price	Value
2026-04-16	Hallal David	Chief Executive Officer	Sell	-30,615	$49.57	-$1,517,723
2026-04-16	Sinha Vikas	Chief Financial Officer	Sell	-10,410	$49.57	-$516,071
2026-04-16	Vaishnaw Akshay	President of R&D	Sell	-12,246	$49.57	-$607,089
2026-04-16	Woods Keith	Chief Operating Officer	Sell	-10,220	$49.57	-$506,651

Source: SEC Form 4 filings.

Next expected filings

~2026-08-06 10-Q expected by 2026-08-07 (in 50 days)
~2026-11-14 10-Q expected by 2026-11-15 (in 150 days)
~2027-03-01 10-K expected by 2027-03-09 (in 257 days)
~2027-05-07 10-Q expected by 2027-05-08 (in 324 days)

Predicted from historical filing cadence; not an SEC commitment.

Recent SEC filings

2026-05-07 8-K Earnings Release; Regulation FD Disclosure; Financial Statements and Exhibits
2026-05-07 10-Q Quarterly Report
2026-04-22 DEF 14A Proxy Statement
2026-03-31 8-K Regulation FD Disclosure; Other Events; Financial Statements and Exhibits
2026-03-03 10-K Annual Report
2026-03-03 8-K/A Earnings Release; Regulation FD Disclosure; Financial Statements and Exhibits
2026-03-03 8-K Earnings Release; Regulation FD Disclosure; Financial Statements and Exhibits
2026-01-12 8-K Earnings Release; Regulation FD Disclosure; Other Events; Financial Statements and Exhibits
2025-12-02 8-K Other Events
2025-11-14 10-Q Quarterly Report
2025-11-14 8-K Other Events; Financial Statements and Exhibits
2025-11-14 8-K Earnings Release; Regulation FD Disclosure; Financial Statements and Exhibits
2025-10-14 8-K Other Events
2025-09-23 8-K Regulation FD Disclosure; Other Events; Financial Statements and Exhibits
2025-08-06 10-Q Quarterly Report

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