SRRK 10-K & 10-Q changes, risk factors and insider trading

Risks Related to Our Intellectual Property

The regulatory approval process for our product candidatesapitegromab in the U.S., EU and other jurisdictions will be lengthy, time-consuming and inherently unpredictable and we may fail to receive or be delayed in receiving regulatory approval of apitegromab, SRK-181,or SRK-439we may receive regulatory approval for only a subset of SMA patients. The CRL received from the FDA in September 2025 will require us to resubmit the apitegromab BLA and futureour productprogress candidates.toward potential commercialization of apitegromab has been delayed. The CRL could impact the current review process of our MAA with the EMA, which could result in a delay or a resubmission of the MAA to the EMA.

The research, testing, manufacturing, labeling, approval, sale, import, export, marketing, promotion and distribution of drug products, including biologics, are subject to extensive regulation by the FDA in the U.S. and other regulatory authorities outside the U.S. We are not permitted to market any biological product in the U.S. until we receive a biologics license from the FDA. Prior to filingsubmitting the Biologics License Application (“BLA”) to the U.S. FDA in January 2025 and submitting the MAA to the EMA in March 2025 for apitegromab as a treatment for patients with SMA in January 2025,SMA, we havehad not submitted a BLA to the FDA or MAA to the EMA or similar marketing application to comparable foreign authorities. A BLA must include extensive preclinical and clinical data and supporting information to establish that the product candidate is safe, pure and potent for each desired indication. FDAFDA, EMA or comparable foreign regulatory authorities’ approval of a new biologic or drug generally requires dispositive data from twoone (andor in some cases, one)more adequate and well-controlled pivotal Phase 3 clinical trials of the biologic or drug in the relevant patient population. The FDA, EMA or comparable foreign regulatory authorities may disagree with the design or implementation of our clinical trials or our analysis or interpretation of data from preclinical studies or clinical trials, the results of our clinical trials may not meet the level of statistical significance or amount of data required for approval, regulatory authorities may not agree with the statistical methods we used to evaluate our clinical data, or we may be unable to demonstrate that our product candidates’apitegromab’s clinical and other benefits outweigh theirits safety risks. Even if the FDA, EMA, or other regulatory authorities were to grant approval for apitegromab in SMA, one or more of these regulatory authorities may determine that the approval should be limited to a subset b of SMA patients, which could restrict the commercial potential of apitegromab in SMA. A BLA to the FDA or MAA to the EMA must also include significant information regarding the chemistry, manufacturing, and controls for the product, and the manufacturing facilities must complete a successful pre-license inspection as well as certain key clinical sites conducting our clinical trials. The FDA, EMA or comparable foreign regulatory authorities may fail to approve the manufacturing processes or facilities of third-party manufacturers with which we contract for clinical and commercial supplies.

Although we are preparing our commercialization capabilities in anticipation of a potential approval and commercial launch of apitegromab,apitegromab in the United States and Europe, we have no prior sales or distribution experience and limited capabilities for marketing and market access. We expect to invest significant financial and management resources over time to establish compliance, medical affairs and commercial organizations for the marketing, sales and distribution of apitegromab in the United States as well asand Europe, if approved in each jurisdiction, and other capabilities and infrastructure to support commercial operations. If we are unable to establish these commercial capabilities and infrastructure in a timely manner or to enter into agreements with third parties to market, sell, and/or distribute apitegromab if approved, we may be unable to complete a successful commercial launch. To the extent we enter into agreements with third parties, the revenue we receive may depend upon the efforts of such third parties, over which we may have limited or no control, and our revenue from product sales may be lower than if we had commercialized the products ourselves. We also face competition in our search for third parties to assist us with the distribution, sales and marketing of our products.

Furthermore, we intend to commercialize apitegromab in the United States and Europe initially, and globally, if approved. In order to do so, we must build, on a territory-by-territory basis, marketing, sales, distribution, managerial and other capabilities or make arrangements with third parties to perform these services, and we may not be successful in doing so.

Changes or disruptions at the FDA and other government agencies caused by funding cuts, government shutdowns, personnel reductions, substantial changes in leadership and policy, or other changes or disruptions to these agencies’ operations could prevent these agencies from performing functions on which the operation of our business relies, including the timely review and potential approval of our BLABLA, application,when resubmitted, and any such disruptions and changes could negatively impact our business.

The ability of the FDA and foreign regulatory authorities to review and or approve new products can be affected by a variety of factors, including government budget and funding levels, staffing levels, and statutory, regulatory, and policy changes, the FDA’s and foreign regulatory authorities' ability to hire and retain key personnel and accept the payment of user fees, and other events that may otherwise affect the FDA’s ability to perform routine functions. Average review times at the FDA and foreign regulatory authorities have fluctuated in recent years as a result. Disruptions at the FDA and other agencies, including substantial leadership, personnel, and policy changes, may also slow the time necessary for new drugs to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. ForIn example, over the last few months,2025, the U.S. government hashas, among other measures, issued executive orders and undertaken reductions in force that couldhave adversely impactimpacted FDA staffing and resources. Such changes could significantly impact the ability of the FDA to timely review and take action on our regulatory submissions, which could have a material adverse effect on our business. Further, in our operations as a public company, future government shutdowns or substantial leadership, personnel, and policy changes could impact our ability to access the public markets and obtain necessary capital in order to properly capitalize and continue our operations.

In addition, changes in the requirements and policies of the FDA and other regulatory agencies with jurisdiction over our products, including applicable pricing and reimbursement frameworkframeworks under federal healthcare programsprograms, could affect the commercial viability of our products, create revenue uncertainty, and impact our ability to achieve profitability. Additionally, regulatory changes may introduce new challenges in obtaining FDA approval or navigating commercialization, and any delay in securing applicable regulatory approvals would adversely affect our business and prospects. These uncertainties could also present new challenges and/or opportunities as we navigate the submissionresubmission of our BLA to the FDA and make other preparations for potential commercialization. Any delay in obtaining, or our inability to obtain, applicable regulatory approvals would delay or prevent commercialization of apitegromab and could materially adversely impact our business and prospects.

Many of the factors that cause, or lead to, a delay in the initiation or completion of clinical trials may also ultimately lead to the denial of regulatory approval or limit market acceptance of our product candidates. For example, we anticipate some of our future trials to, in part, utilize an open-label trial design, and our ongoing Phase 1 DRAGON clinical trial for SRK-181 in cancer immunotherapy and our ongoing ONYX long-term extension study for apitegromab in patients from both the TOPAZ and SAPPHIRE trials,trials utilizeutilizes an open-label trial design. An open-label trial is one where both the patient and investigator know whether the patient is receiving the test article or either an existing approved drug or placebo. Open-label trials are subject to various limitations that may exaggerate any therapeutic effect as patients in open-label studies are aware that they are receiving treatment. Open-label trials may be subject to a patient bias, for example, if patients perceive their symptoms to have improved merely due to their awareness of receiving an experimental treatment. Open-label trials also may be subject to an investigator bias where those assessing and reviewing the physiological outcomes of the clinical trials are aware of which patients have received treatment and may interpret the information of the treated group more favorably given this knowledge. The potential sources of bias in clinical trials as a result of open-label design may not be adequately mitigated and may cause any of our trials that utilize such design to fail and additional trials may be necessary to support future marketing applications. In addition, other types of trials (including randomized, double-blind, parallel arm studies), particularly if smaller in size or if limited to one study, are also subject to potential sources of bias and limitations that may exaggerate any therapeutic effect or falsely identify a positive efficacy signal, or conversely, fail to detect an efficacy signal when in fact there may actually be a positive therapeutic effect. Furthermore, we are conducting clinical trials with apitegromab in SMA, but by using apitegromab in a Phase 2 obesity clinical trial, we may become aware of safety information associated with apitegromab that we did not observe when we used apitegromab in our clinical trials in SMA. We, the FDA, the competent authorities and/or ethics committees of the EU Member States or other applicable regulatory authorities for their jurisdictions, or an IRB for their site(s) may suspend clinical trials of a product candidate at any time for various reasons, including a belief that subjects or patients in such trials are being exposed to unacceptable health risks or adverse side effects.

Our product development costs will increase if we experience delays in clinical testing or marketing approvals. We do not know whether any of our clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Significant clinical trial delays could also shorten any periods during which we may have the exclusive right to commercialize our product candidates and may allow our competitors to bring products to market before we do, potentially impairing our ability to successfully commercialize our product candidates and harming our business and results of operations.candidates. Any delays in our clinical development programs may harm our business, financial condition and results of operations significantly.

Apitegromab and SRK-181 are our two clinical-stage product candidates. Patients in ONYX, our long-term extension study for patients from both the TOPAZ and SAPPHIRE studies, and OPAL, our Phase 2 clinical trial of apitegromab in children under the age of two living with SMA, are receiving apitegromab in conjunction with an approved SMN therapy.targeted treatment. These patients are reliant on the continued use and availability of such therapies.treatments. If access to an approved SMN therapytargeted treatment such as nusinersen or risdiplam becomes limited or is unavailable, we may be forced to pause or stop our ONYX long-termor extensionOPAL clinical trials, or the medical condition of patients may be affected which could negatively affect the efficacy and safety results for apitegromab in the trialstrial or reduce the amount of data or confound the data from this trial. In May 2024, we initiated the Phase 2 EMBRAZE proof-of-concept trial of apitegromab in combination with approved GLP-1 RAs in obesity. This study relies upon the continued availability of such GLP-1 RA. Access to approved GLP-1 RAs are limited for use in clinical trials and may continue to be limited for such use. If GLP-1 RAs become more limited or unavailable, we may be unable to enroll, or may be delayed in enrolling patients, or may be forced to stop our Phase 2 study. While we have obtained substantial supply of an approved GLP-1 RA for use in this Phase 2 study, we cannot assure you that we will be able to obtain adequate supply for future studies of our product candidate in obesity. Patients in Part B of our ongoing Phase 1 DRAGON clinical trial of SRK-181 in patients with locally advanced or metastatic solid tumors that exhibit resistance to anti-PD-(L)1 antibody therapies are receiving SRK-181 in conjunction with an approved anti-PD-(L)1 therapy such as pembrolizumab. If access to the approved anti-PD-(L)1 therapy becomes limited or is unavailable, we may be forced to pause or stop our Phase 1 DRAGON clinical trial, or the medical condition of patients may be affected which could negatively affect the efficacy and safety results for SRK-181 in the trial. Any delay or suspension of our clinical trials would significantly and delay our clinical development programs and harm our business, financial condition and results of operations.

The results or success of preclinical studies and early-stage clinical trials of our product candidates may not be predictive of future results or replicated in later preclinical studies or later-stage clinical trials. Preclinical studies and early-stage clinical trials are primarily designed to study PK and PD, understand the side effects of product candidates, and evaluate various doses and dosing schedules. Our current or future product candidates may demonstrate different chemical, biological and pharmacological properties in patients than they do in laboratory studies or may interact with human biological systems in unforeseen or harmful ways. Product candidates in later-stages of clinical trials may fail to show desired pharmacological properties or produce positive safety and efficacy results despite having progressed through preclinical studies and early-stage clinical trials. We completed a Phase 1 clinical trial for apitegromab in healthy adult volunteers and our Phase 2 TOPAZ clinical trial for the treatment of patients with Type 2 and Type 3 SMA. In 2024, we announced data from the Phase 2 TOPAZ trial extension period which showed patient outcomes at 48 months of treatment with apitegromab. These data show that continued treatment with apitegromab over the extended period was associated with sustained clinical benefit, a continued favorable safety profile with no new safety findings, and a retention rate of over 90% in patients with nonambulatory Types 2 and 3 SMA receiving SMN therapy. In January 2022, we initiated our Phase 3 SAPPHIRE clinical trial of apitegromab for the treatment of patients with Type 2 and Type 3 SMA and in October 2024, we announced positive top-line data from our Phase 3 SAPPHIRE clinical trial evaluating the efficacy and safety of apitegromab. We also announced in October 2023 our plans to expand into cardiometabolic disorders based on preclinical data with SRK-439, and we initiated the Phase 2 EMBRAZE proof-of-concept trial of apitegromab in combination with a GLP-1 RA in obesity in May 2024 with top-line results expected in the second quarter of 2025. We cannot assure you that any future clinical trials of apitegromab, such as our Phase 2 clinical trial in obesity, or of SRK-439 will show positive results. Additionally, product candidates evaluated in one disease indication may interact in unforeseen or harmful ways in a patient population with a different disease indication than was previously studied. For example, weapitegromab havewas initiatedevaluated ain our Phase 3 SAPPHIRE clinical trial for the treatment of patients with Type 2 and Type 3 SMA and apitegromab was evaluated in our Phase 2 clinicalEMBRAZE proof-of-concept trial ofin apitegromabcombination with tirzepatide in obesity. ApitegromabTop-line maydata from each clinical trial have been released and apitegromab did not interact in unforeseenany new ways despite the different patient population and disease indications studied in each trial. We cannot assure you that any future clinical trials of apitegromab, such as our Phase 2 FORGE clinical trial in patients with FSHD, or differentany of our other anti-myostatin antibodies will show positive results or interact in ways insimilarly theto obesitythat populationwhich thanwas previously studied in thea SMAdifferent patientdisease population.indication. There can be no assurance that any of our current or planned clinical trials will ultimately be successful or support further clinical development of any of our product candidates. There can also be no assurance that any of our future clinical trials will show similar results to our earlier clinical trials or support further development or registration of any of our product candidates.

From time to time, we may publish interim, initial, or preliminary data, including interim top-line results or initial or preliminary results from our clinical trials. Any interim, initial or preliminary data or results from clinical trials, including interim top-line results and other results published from our clinical trials may materially change as more patient data become available. Preliminary, initial, interim or top-line results also remain subject to audit, validation and verification procedures that may result in the final data being materially different from the interim, initial or preliminary data we previously published. As a result, interim, initial or preliminary data may not be predictive of final results and should be viewed with caution until the final data are available. We may also arrive at different conclusions, or considerations may qualify such results, once we have received and fully evaluated additional data. For example, clinical data from our Phase 1 DRAGON trial in cancer immunotherapy, including preliminary safety, efficacy and biomarker data were presented in June 2024 at the ASCO 2024 annual meeting and in November 2024 at the SITC 39th Annual Meeting, and we will continue to present data from our Phase 1 DRAGON trial while the trial is ongoing. Tumor response data is based on assessments by site investigators. Central reads for the tumor responses are also being conducted, with a comprehensive review of the central reads to be performed once completed within and/or across the cohorts. Differences between preliminary, initial or interim data and final data could adversely affect our business.

There is a high failure rate for drugs and biologics proceeding through clinical trials. A number of companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical development even after achieving promising results in earlier studies, and we cannot be certain that we will not face similar setbacks. Many drugs have failed to replicate efficacy and safety results in larger or more complex later stage trials. Moreover, preclinical and clinical data are often susceptible to varying interpretations and analyses, and many companies that believed their product candidates performed satisfactorily in preclinical studies and clinical trials nonetheless failed to obtain regulatory approval. If we fail to produce positive results in our ongoing and planned preclinical studies and clinical trials inwith apitegromab, SRK-181, or SRK-439 or if a regulatory authority interprets and analyzes the results as not positive, the development timeline and regulatory approval and commercialization prospects for our product candidates, and, correspondingly, our business and financial prospects, may be materially adversely affected.

For example, we are initially developing apitegromab for the treatment of SMA,people with FSHD, a rare disease, affecting an estimated 20,00030,000 patientspeople in the U.S. and Europe. As a result, we may encounter difficulties enrolling patients in our clinical trials for apitegromab in FSHD due, in part, to the small size of this patient population. In addition, our clinical trials will compete with other clinical trials for product candidates that are in the same therapeutic areas as our product candidates, and this competition will reduce the number and types of patients available to us, because some patients who might have opted to enroll in our trials may instead opt to enroll in a trial being conducted by one of our competitors. Since the number of qualified clinical investigators is limited, we expect to conduct some of our clinical trials at the same clinical trial sites that some of our competitors use, which will reduce the number of patients who are available for our clinical trials in such clinical trial site. Additionally, patients may opt out of participation in clinical trials in favor of treatment with FDA-approvedFDA approved therapies, or therapies approved in the EU or other foreign jurisdictions.

We rely especially heavily on third parties over the course of our clinical trials, and, as a result, have limited control over the clinical investigators and limited visibility into their day-to-day activities, including with respect to their individual employment policies or compliance with the approved clinical protocol. Nevertheless, we are responsible for ensuring that each of our trials is conducted in accordance with the applicable protocol, legal and regulatory requirements and scientific standards, and our reliance on third parties does not relieve us of our regulatory responsibilities. We and these third parties are required to comply with Good Clinical Practice (“GCP”) requirements, which are regulations and guidelines enforced by the FDA and comparable foreign regulatory authorities for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. Regulatory authorities enforce these GCP requirements through periodic inspections of trial sponsors, clinical investigators and trial sites. If we or any of these third parties fail to comply with applicable GCP requirements, the clinical data generated in our clinical trials may be deemed unreliable and the FDA or comparable foreign regulatory authorities may require us to suspend or terminate these trials or perform additional preclinical studies or clinical trials before approving our marketing applications. We cannot be certain that, upon inspection, such regulatory authorities will determine that any of our clinical trials comply with the GCP requirements. We also are required to register certain ongoing clinical trials and post the results of completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within specified timeframes. Failure to do so can result in civil monetary penalties, adverse publicity and civil and criminal sanctions. The FDA and National Institutes of Health have signaled the government’s willingness to begin enforcing these registration and reporting requirements against non-compliant clinical trial sponsors. As a result, our financial results and the commercial prospects for our product candidates would be harmed, our costs could increase and our ability to generate revenue could be delayed.

Any third parties conducting aspects of our preclinical studies or clinical trials will not be our employees and, except for remedies that may be available to us under our agreements with such third parties, we cannot control whether they devote sufficient time and resources to our preclinical studies and clinical trials. The third party CROs and clinical trial sites that conduct our clinical trials havemay experiencedexperience staffing shortages and the inability of a CRO or clinical trial site to maintain appropriate levels of competent staffing to support the demands of our clinical trials could negatively impact the execution of our clinical trials. These third parties may also have relationships with other commercial entities, including our competitors, for whom they may also be conducting clinical trials or other product development activities, which could affect their performance on our behalf. If these third parties do not successfully carry out their contractual duties or obligations or meet expected deadlines if they need to be replaced or if the quality or accuracy of the preclinical or clinical data they obtain is compromised due to the failure to adhere to our protocols or regulatory requirements or for other reasons, our development timelines, including clinical development timelines, may be extended, delayed or terminated and we may not be able to complete development of, receive regulatory approval of or successfully commercialize our product candidates. As a result, our financial results and the commercial prospects for our product candidates would be harmed, our costs could increase and our ability to generate revenue could be delayed.

We have received Orphan Drug designation from the FDA for apitegromab for the treatment of SMA and the EC granted Orphan Medicinal Product designation to apitegromab for the treatment of SMA. We may seek Orphan Drug designation from regulatory authorities in other jurisdictions for apitegromabapitegromab. and Orphan Drug designation from the FDA, EC or regulatory authorities in other jurisdictions for our other product candidates. In any of these instances, weWe may not receive the requested designation or we may be unable to realize the benefits associated with Orphan Drug designation, including the potential for market exclusivity.

We have received Rare Pediatric Disease designation for apitegromab for the treatment of SMA. Designation of a biologic as a product for a rare pediatric disease does not guarantee that a BLA for such biologic will meet the eligibility criteria for a rare pediatric disease priority review voucher at the time the application is approved. UnderPursuant to the Federal Food, Drug, and Cosmetic Act, in January 2025 we will need to requestrequested a rare pediatric disease priority review voucher in our originalBLA BLAsubmission for apitegromab.apitegromab for the treatment of SMA and in March 2025 the FDA granted priority review of this BLA. The FDA may determine that athe resubmitted BLA for apitegromab, if approved, does not meet the eligibility criteria for a rare pediatric disease priority review voucher, including for the following reasons:

Receiving and maintaining regulatory approval of our product candidatesapitegromab in one jurisdiction does not mean that we will be successful in receiving or maintaining regulatory approval of our product candidatesapitegromab in other jurisdictions.

Receiving and maintaining regulatory approval of our product candidatesapitegromab in one jurisdiction does not guarantee that we will be able to receive or maintain regulatory approval in any other jurisdiction, but a failure or delay in receiving regulatory approval in one jurisdiction may have a negative effect on the regulatory approval process in other jurisdictions. Even if the FDA grants marketing approval of a product candidate,apitegromab, the EC, the competent authorities of EU Member States or comparable regulatory authorities in foreign jurisdictions may not approve the manufacturing, marketing and promotion of the product candidateapitegromab in other countries. Approval procedures vary among jurisdictions and can involve requirements and administrative review periods different from, and greater than, those in the U.S., including additional preclinical studies or clinical trials, as clinical trials conducted in one jurisdiction may not be accepted by regulatory authorities in other jurisdictions. In many jurisdictions outside the U.S., a product candidateapitegromab must be approved for reimbursement before it can be approved for sale in that jurisdiction. In some cases, the price that we intend to charge for our products is also subject to approval.

We may also submit marketing applications in other countries. Regulatory authorities in jurisdictions outside of the U.S. have requirements for approval of product candidatesapitegromab with which we must comply prior to marketing in those jurisdictions. Receiving foreign regulatory approvals and compliance with foreign regulatory requirements could result in significant delays, difficulties and costs for us and could delay or prevent the introduction of our productsapitegromab in certain countries. If we fail to comply with the regulatory requirements in international markets and/or receive applicable marketing approvals, our target market will be reduced and our ability to realize the full market potential of our product candidatesapitegromab will be harmed.

Even if we receive regulatory approval of any product candidates,apitegromab, we will be subject to ongoing regulatory obligations and continued regulatory review, which may result in significant additional expense and we may be subject to penalties if we fail to comply with regulatory requirements or experience unanticipated problems with our product candidates.apitegromab.

If anyapitegromab of our product candidates areis approved, theywe will be subject to ongoing regulatory requirements, including requirements related to manufacturing, labeling, packaging, storage, advertising, promotion, sampling, record-keeping, import, export, conduct of post-marketing studies and submission of safety, efficacy and other post-marketing information. The safety and efficacy profile of any productapitegromab will continue to be closely monitored by the FDA and comparable foreign regulatory authorities. In addition, we will be subject to continued compliance with current Good Manufacturing Practice (“cGMP”) and GCP requirements for any clinical trials that we conduct post-approval.

Any regulatory approvals that we receive for our product candidatesapitegromab may be subject to limitations on the approved uses for which the product may be marketed or contain requirements for potentially costly post-market testing, including Phase 4 clinical trials and surveillance to monitor the safety and efficacy of the product candidate. The FDA may also require a REMS program as a condition of approval of our product candidates, which could entail requirements for long-term patient follow-up, a medication guide, physician communication plans or additional elements to ensure safe use, such as restricted distribution methods, patient registries and other risk minimization tools.apitegromab.

Later discovery of previously unknown problems with our product candidates,apitegromab, including adverse events of unanticipated severity or frequency, or with our third-party manufacturers or manufacturing processes, or failure to comply with regulatory requirements may result in revisions to the approved labeling to add new safety information; imposition of post-market studies or clinical trials to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program. Other potential consequences include, among other things:

Even if a product candidate we developapitegromab receives marketing approval, it may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success.

If apitegromab, SRK-181, SRK-439 or any future product candidate we developapitegromab receives marketing approval, whether as a single agent or in conjunction with other therapies,approval it may nonetheless fail to gain sufficient market acceptance by physicians, patients, third-party payors, and others in the medical community. There may be delays in getting our product candidates,apitegromab, if approved, on hospital or insurance formulariesformularies, or there may be limitations on coverage that may be available in the early stages of commercialization for newly approved drugs. If anyapitegromab of our product candidates areis approved but failfails to achieve market acceptance among hospitals, physicians, patients or health care payors, we will not be able to generate significant revenues,revenues and we may not become profitable, which would have a material adverse effect on our business, prospects, financial condition and results of operations. For example, doctors may deem it sufficient to treat patients with SMA with an SMNSMN-targeted therapytreatment such as nusinersen or risdiplam, and therefore will not be willing to utilize apitegromab in conjunction with such SMNSMN-targeted therapy. If the product candidates we develop do not achieve an adequate level of acceptance, we may not generate significant product revenues and we may not become profitable.treatment. The degree of market acceptance of any product candidate,apitegromab, if approved for commercial sale, will depend on a number of factors, including:

If we are unable to establish sales and marketing capabilities or enter into agreements with third parties to sell and market apitegromab,apitegromab in the EU, we may not be successful in commercializing apitegromab if and when it is approved.

We anticipate a decision from the EMA in mid-2026 and we have recently begun to build our sales or marketing infrastructure andin Europe. We have limited experience in the sale, marketing or distribution of pharmaceutical products. To achieve commercial success for anyapitegromab, approvedif productapproved, for which we retain sales and marketing responsibilities, we must continue to develop a sales and marketing organization and/or outsource certain functions to third parties.parties, including third party distributors.

There are risks involved both with establishing our own sales and marketing capabilities and with entering into arrangements with third parties to perform these services. For example, recruiting and training a sales force is expensive and time consuming and could delay any product launch. If the commercial launch of a product candidate for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

Factors that may inhibit our efforts to commercialize our product candidatesapitegromab on our own in Europe include:

If we enter into arrangements with third parties to perform sales, marketing, third-party logistics providers, specialty distributors, specialty pharmacies, patient service providerssales and distributionmarketing services, our product revenue or the profitability of these product revenue to us may be lower than if we were to market and sell any products that we developapitegromab ourselves. In addition, we may not be successful in entering into arrangements with third parties to sell and market our product candidatesapitegromab or may be unable to do so on terms that are favorable to us. We may have little control over such third parties, and any of them may fail to devote the necessary resources and attention to sell and market our productsapitegromab effectively. If we do not establish sales and marketing capabilities successfully, either on our own or in collaboration with third parties, we will not be successful in commercializing our product candidates.apitegromab.

Preclinical development is uncertain. Our preclinical programs, such as SRK-439,programs may experience delays or may never advance to clinical trials, which would adversely affect our ability to develop our product pipeline and receive regulatory approvals or commercialize these programs on a timely basis or at all, which would have an adverse effect on our business.

Before we can commence clinical trials for any product candidate, we must complete extensive preclinical studies that support our planned INDs in the U.S., or similar applications in other jurisdictions. We cannot be certain of the timely completion or outcome of our preclinical studies or of the timing of any planned IND submission to the FDA or similar applications in other jurisdictions, and cannot predict if the FDA, EMA or other regulatory authorities will accept our proposed clinical programs or if the outcome of our preclinical studies will ultimately support the further development of our programs. As a result, we cannot be sure that we will be able to submit INDs or similar applications for the clinical development of our preclinical programs, such as our potential IND for SRK-439,programs on the timelines we expect, if at all, and we cannot be sure that submission of INDs or similar applications will result in the FDA, the competent authorities and/or ethics committees in the EU Member States or other regulatory authorities allowing clinical trials to begin.

We have nolimited experience manufacturing our product candidates on a commercial scale. We rely on a limited number of third-party contract manufacturers to manufacture all of our clinical trial product supplies and, if approved, all of our commercial product supplies, including all of our drug substance, drug product,fill-finish, labeling, and packaging. We do not own our own manufacturing facilities for producing any clinical trial or commercial product supplies. Our supply chain also depends on a limited number of suppliers for critical raw materials and components (including container closure systems), and any disruption, quality issue, or shortage could delay manufacturing or regulatory approvals. There can be no assurance that our preclinical, clinical development, and, if approved, commercial product supplies will not be limited or interrupted due to impacts to our third-party contract manufacturers. For example, we rely on a single source supplier for the drug substance and fill-finish manufacture of apitegromabapitegromab, SRK-181 and SRK-181.SRK-439. We are advancing activities at a second US-based fill-finish facility to strengthen supply continuity and support future commercial demand of apitegromab. Any replacement of our current drug substance contract manufacturer or drug productfill-finish contract manufacturer would require significant resources, lead time and expertise because there may be a limited number of qualified replacements. In addition, our ability to procure sufficient supplies for the development of apitegromab, SRK-181, SRK-439 or future product candidates could be impacted by factors outside of our control such as current macroeconomic and geopolitical events andevents, the changing rates of inflation and interest rates.rates and tariff policies. We have no direct control over our contract manufacturers’ ability to maintain adequate quality control, quality assurance and qualified personnel. Furthermore, all of our third-party contract manufacturers supply and/or manufacture materials or products for other companies, which exposes our third-party contract manufacturers to regulatory risks for the production of such materials and products. As a result, failure to satisfy the regulatory requirements for the production of those materials and products may affect the regulatory clearance of our contract manufacturers’ facilities generally.

The manufacturing process for a product candidate is subject to FDA and foreign regulatory authority review. Suppliers and manufacturers must meet applicable manufacturing requirements and undergo rigorous facility and process validation tests required by regulatory authorities in order to comply with regulatory standards, such as cGMP. In the event that any of our manufacturers fails to comply with such requirements or to perform its obligations to us in relation to quality, timing or otherwise, or if our supply of components or other materials becomes limited or interrupted for other reasons, we may be forced to manufactureinternalize thecertain materialsactivities ourselves,or rapidly onboard alternative third-party manufacturing capacity, for which we currently do not have the capabilities or resources, or enter into an agreement with another third-party, which we may not be able to do on reasonable terms, if at all. In some cases, the technical skills or technology required to manufacture our product candidates may be unique or proprietary to the original manufacturer and we may have difficulty transferring such skills or technology to another third-party and a feasible alternative may not exist. These factors would increase our reliance on the original manufacturer or require us to obtain a license from such manufacturer in order to have another third-party manufacture our product candidates. If we must change manufacturers for any reason, we willmay be required to verifyqualify thatand thevalidate a new manufacturermanufacturer’s maintainsfacilities, facilitiesprocesses and proceduresquality thatsystems complyfor compliance with quality standards and with all applicable regulationsregulatory andrequirements, guidelines.including cGMP. We willmay also need to verify, such as through aconduct manufacturing comparability study,studies to demonstrate that any new manufacturing process will produce ourproduces product candidateconsistent according to thewith specifications previously submitted to the FDA or anotherother regulatory authority.authorities. TheThese activities could result in delays associatedand withincreased thecosts verification of a new manufacturerand could negatively affect our ability to develop and commercialize our product candidates in a timely manner or within budget.

We expect to continue to rely on third-party manufacturers for commercial supplies of drug substance, drug product, fill-finish, and packaged and labeled product for apitegromab, if we receive regulatory approval. We will also rely on our contract manufacturers to manufacture sufficient quantities of apitegromab to produce validation batches. We do not have long-term supply agreements in place with many of our contract manufacturers, and each batch of our drug product for our product candidates is individually contracted through a purchase order governed by master service and quality agreements. If ourany existingof drugthese manufacturers are unwilling to or unable to supply adequate quantities of product contracton manufacturersacceptable for our product candidates are not willing to enter into long-term supply agreements,terms or are not willingtimelines, or are unable to supplycomply productwith candidatecGMP suppliesor toother us,applicable requirements, we couldmay be required to engagequalify newand contractonboard manufacturersalternative who would need to scale up the manufacturing process before we would be able to use the product candidate supplies they manufacture,suppliers, which could result in delays to our clinical trialsdevelopment, regulatory submissions or futureapprovals, commercializationor plans, if we are successful and gain approval.commercialization.

In addition, we contract with fill and finishing providers which we believe have the appropriate expertise, facilities and scale to meet our needs. Failure to maintain compliance with cGMP can result in aregulatory contractoraction receivingagainst our third-party manufacturers, including FDA sanctions, which cancould impactdisrupt our abilitymanufacturing toand operatesupply orchain and lead to delays in anyour clinical development programsprograms, regulatory submissions or approvals, or commercial supply.supply, Weif believe that our current fill and finish contractors are operating in accordance with cGMP, but we can give no assurance that the FDA, EMA, competent authorities of the EU Member States or other regulatory agencies will not conclude that a lack of compliance exists.approved. In addition, any delaydelays in contractingsecuring or maintaining manufacturing capacity for filldrug substance, fill-finish, labeling and finish services,packaging, or failurefailures ofby theour contract manufacturermanufacturers or suppliers to perform the services as needed,required, maycould delay any clinical trials, registrationregulatory andfilings, or commercial launches, which could negatively affect our business.

Our reliance on third parties, such as manufacturers, third-party logistics providers, specialty distributors, specialty pharmacies, and patient service providers, may subject us to risks relating to manufacturing scale-up and may cause us to undertake substantial obligations, including financial obligations.

In order toTo conduct later-stage clinical trials,trials or,and, if approved, produce commercial product, we will need to manufacture suchour product candidatecandidates in largelarger quantities.quantities Inand particular,at weappropriate expectquality tostandards. We rely on ourthird-party contract manufacturers to scale our manufacturing processes for futureour clinical trials of apitegromab,programs, and if our development efforts are successful and if apitegromab is approved, for commercial supplysupply. ofWe apitegromab.and We, or anyour manufacturing partners,partners may be unable to successfully increase the manufacturing capacity for apitegromab in a timely or cost-effective manner to meet our supply requirements. If we successfully commercialize any of our product candidates, we may be required to establish large-scale commercial manufacturing capabilities. As our drug development pipeline increasesmanner, and matures,quality we will have a greater need for clinical study and commercial manufacturing capacity. In addition, quality-controlcontrol issues may arise during scale-upprocess activities.scale-up, technology transfer, or commercial production. If we, or any manufacturing partners, are unable to successfullyscale scale-up the manufacturemanufacturing of our product candidates in sufficient qualityquantity andor quantity,quality, thedevelopment development, testing,activities, clinical trials, andregulatory if approved, commercial supply, of that product candidate may be delayedsubmissions, or infeasible,approvals, and regulatory approval,or commercial launch or commercialand supply of any resulting product maycould be delayeddelayed, disrupted, or notbecome received,infeasible, which could significantlymaterially harmaffect our business. In September 2025, we received a CRL from the FDA for the apitegromab BLA citing observations identified during an FDA inspection of a third-party fill-finish facility. The facility received a Form 483 in July 2025, the facility was classified as OAI and in November 2025 received a warning letter from the FDA. The observations were related to the facility and were not specific to apitegromab.

Our reliance on third-party logistics providers, specialty distributors, specialty pharmacies, and patient services providers may subject us to risks that could impact the commercialization and patient access to apitegromab. If apitegromab is approved, we expect to use limited distribution agreements, which could concentrate supply with a small number of specialty pharmacies, increasing the risk of distribution disruptions, capacity constraints, and gaps in patient access if these partners fail to perform. Additionally, third parties manage high-touch patient support, reimbursement processing, and copay assistance, and any failures in these areas could lead to delays in initiation of treatment, coverage denials, and financial barriers for patients. Additionally, challenges such as disruptions in logistics, product-handling or quality-control issues, non-compliancecybersecurity withor privacy incidents, licensing or other regulatory requirements,non-compliance, or delays in onboarding key distribution partners may arise.arise and may cause us to undertake substantial obligations, including financial obligations. If we or our third-party distribution service providers fail to scale and manage commercial distribution operations efficiently, the launch, commercialization, or continued supply of apitegromab may be delayed or compromised, which could significantly harm our business, reputation, and financial results.

As our clinical development plans and commercialization strategies continue to develop and expand, we expect we will need to hire additional managerial, clinical development, scientific, regulatory, commercial, and administrative personnel. Our ability to compete in the highly competitive biotechnology industry depends upon our ability to attract and retain highly qualified specialized personnel. As apitegromab approaches commercialization,commercialization globally, we will also need to hire sales, marketing and other commercial personnel.personnel in the new markets we plan to enter. Future growth would impose significant added responsibilities on members of management, including:

Our future financial performance and our ability to commercialize apitegromab, SRK-181, SRK-439 and future product candidates, if approved, will depend, in part, on our ability to effectively manage any future growth, and our management may also have to divert a disproportionate amount of its attention away from day-to-day activities in order to devote a substantial amount of time to managing these growth activities.

We may not be able to attract or retain qualified management and scientific personnel in the future due to the intense competition for a limited number of qualified personnel in the biopharmaceutical space, especially those engaged in oncology and immuno-oncology and cardiometabolic fields.space. In this highly competitive market, there may be increased costs to attract and retain qualified personnel. Many of the other pharmaceutical companies that we compete against for qualified personnel have greater financial resources, different risk profiles and a longer history in the industry than we do. They also may provide more diverse opportunities and better chances for career advancement. Some of these characteristics may be more appealing to high quality candidates than what we have to offer. If we are not able to offer competitive compensation or appealing opportunities for high quality candidates, we may not be able to attract or retain qualified candidates and personnel. If we are not able to effectively expand our organization by hiring new employees and expanding our groups of consultants and contractors, we may not be able to successfully implement the tasks necessary to further develop and commercialize apitegromab, SRK-181, SRK-439 or any future product candidatesapitegromab and, accordingly, may not achieve our research, development and commercialization goals.

We are a late-stageglobal biopharmaceutical company focuseddedicated onto improving the discovery,lives developmentof children and deliveryadults ofwith innovativeSMA medicinesand foradditional therare, treatmentsevere ofand seriousdebilitating diseasesneuromuscular in which signaling by protein growth factors plays a fundamental role.diseases. As a global leader in transformingthe growthbiology factorof beta (“TGFβ”) superfamily biology,superfamily, our novel understanding of the molecular mechanisms of growth factor activation enabled usthe todevelopment developof a proprietary platform for the discovery and development of monoclonal antibodies that locally and selectively target the precursor, or latent, forms of growth factors. ByBased targetingon theour signalinginnovative, proteins at the cellular levelproprietary, and actingscalable intechnology the disease microenvironment,platform, we believeare we may avoid the historical dose-limiting safety challenges associated with inhibiting growth factors for therapeutic effect. We believe our focus on biologically validated growth factors may facilitatebuilding a moreworld-leading efficientanti-myostatin development path.pipeline.

We have incurred significant operating losses since inception. Our net losses were $246.3$377.9 million for the year ended December 31, 2024.2025. As of December 31, 2024,2025, we had an accumulated deficit of $922.7$1.3 million.billion. We expect to continue to incur significant expenses and operating losses for the foreseeable future in performing our ongoing activities, as we:

To date, we have not generated any revenue from product sales. If we successfully complete clinical development and obtain regulatory approval for apitegromab, SRK-181, SRK-439 or any of our future product candidates,apitegromab we may generate revenue in the future from product sales. In addition, if we obtain regulatory approval for apitegromab, SRK-181, SRK-439 or any of our future product candidates,apitegromab we have and expect to incur significant expenses related to developing our commercialization capabilities to support product sales, marketing and distribution activities.

A change in the outcome of anyAny of these variablesvariables, 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 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 feesservices and corporate expenses. We expect general and administrative expense to increasecontinue to be substantial as we continue to invest in building the infrastructure to support the commercialization of apitegromab.

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, including the completion of our Phase 3 SAPPHIRE pivotal clinical trial in SMA, the conduct of ONYX, the conduct of our long-termPhase extension2 studyOPAL fortrial in SMA patients from bothunder the TOPAZage andof SAPPHIRE studies andtwo, the associatedconduct drugof supply,our planned Phase 2 FORGE trial in FSHD patients, as well as costs associated with supporting our cardiometabolicanti-myostatin program, including our Phase 2 EMBRAZE proof-of-concept trial of apitegromab and our preclinical program, SRK-439. Additionally, we will continue to invest in our pipeline. We expect costs of our SRK-181 program to decrease, as we completed enrollment of the Phase 1 DRAGON clinical trial in DecemberJune 2023.2025.

General and administrative expense was $176.2 million and $67.5 million for the yearyears ended December 31, 20242025 comparedand to2024, $49.4 million for the year ended December 31, 2023,respectively, an increase of $18.1$108.7 million or 36.7%.161.0%. The total increase was primarily associateddriven withby investments in infrastructure to support launch readiness for apitegromab, including an increase of approximately $32.3 million in employee-related costs including salaries, bonus, benefits and payroll taxes related to increased headcount, an increase of $6.0 million in severance and other costs associated with our leadership change, an increase of $21.7 million in non-cash equity-based compensation expense related to increased headcount, an increase in additioncharges in non-cash equity-based compensation expense of $12.6 million related to the modification of certain equity awards and an increase of approximately $33.6 million in professional service fees. The increase in headcount is partially associated with the hiring of our commercial and field-facing teams. We expect general and administrative expenseexpense, excluding the $18.6 million in charges associated with the leadership change, to increasecontinue to be substantial as we continue to invest in building the infrastructure to support the commercialization of apitegromab.

The change in other income (expense), net was primarily attributable to an increase in interest income earned due to higher interest rates and higher average balances in our cash, cash equivalents and marketable securities, partially offset by an increase in interest expense related to the Loan and Security Agreement, also due to higher interest rates.securities.

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 IPO, and issuance of our common stock through our IPO in 2018, to Gilead in an exempt private placement, through multiple secondary public offerings, including our recent follow-on offering in October 2024 (see Note 9)offerings and through “at-the-market offerings” (“ATM”) sales, as well as payments from our research collaborations and the Loan and Security Agreement entered into in October 2020 and subsequently amended (see Note 1314).

During the year ended December 31, 2024,2025, our cash, cash equivalents and marketable securities balance increaseddecreased by $157.3$69.7 million. The change was primarily thedue result of proceeds from our equity offering completed in October 2024 and exercises of stock options and warrants, partially offset byto 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.debt, partially offset by proceeds from our debt facility, sales under our ATM program and the exercises of stock options and common warrants.

Our current ATM program,program with Jefferies, established in November 2022, allows for the sale of shares of our common stock havingfrom an aggregate offering price of uptime to $100time million.in “at-the-market offerings” through Jefferies as the Company’s sales agent. As of December 31, 2024,2025, we sold 619,2903,386,290 shares of our common stock, generating net proceeds of $5.2$96.9 million, under the ATM program. NoOf salesthis wereamount, madewe sold 2,767,000 shares of our common stock under the ATM program during the year ended December 31, 2024.2025, Ingenerating Octobernet 2021, we sold 500,000 sharesproceeds of our$91.7 common stock through a sale in our prior ATM program (in place between March 2021 and June 2022) and received $13.1 million in net proceeds, after deducting commissions and fees.million.

OnIn February 10, 2025, we entered into the Amended and RestatedExisting Loan and Security Agreement with Oxford for up to $200 millionmillion, of which $25.0 million from Tranche 1 was received in October 2020 and2020, $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 (see Note 1314). The Amended and Restated Loan and Security Agreement consolidates the existing outstanding loan tranches solely with Oxford.

During the year ended December 31, 2024,2025, 2,526,833none of the Company’s pre-funded warrants were exercised. As of December 31, 2024,2025, the Company had 17,362,147 pre-funded warrants outstanding.

During the year ended December 31, 2024,2025, 1,309,4928,678,664 of the Company’s common warrants were exercised.exercised, generating net proceeds of $63.8 million. In October 2025, the Company issued 250,000 common warrants in exchange for non-employee services. As of December 31, 2024,2025, the Company had 8,678,664250,000 common warrants outstanding.

Net cash usedprovided inby investing activities was $76.1$218.7 million for the year ended December 31, 2024,2025, compared to net cash provided by investing activities of $41.1$76.1 million for the year ended December 31, 2023.2024. Net cash used in and provided by investing activities for both periods was primarily associated with transactions involved in the routine management ofinvolving our marketable securities.

Net cash provided by financing activities was $228.4 million for the year ended December 31, 2025, compared to $353.0 million for the year ended December 31, 2024,2024. comparedNet tocash $102.6provided millionby financing activities for the year ended December 31, 2023.2025 was primarily attributable to $91.7 million in net proceeds from the sale of common shares under our ATM program, $50.0 million in proceeds from our debt facility, $63.8 million from the exercise of common warrants and $23.8 million from the exercise of stock options, partially offset by the net impact of our debt refinancing. Net cash provided by financing activities for the year ended December 31, 2024 was primarily attributable to net proceeds from an equity offering completed in October 2024, in addition to stock option and warrant exercises. Net cash provided by financing activities for the year ended December 31, 2023 was primarily attributable to net proceeds from an equity offering completed in October 2023.

We expect our expenses to be substantial as we continue the research and development of apitegromab in SMA. In addition, we willare seekseeking marketing approval for apitegromab, and if we seek marketing approval for any of our future product candidates, 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 related to SRK-181 as we continueinvest in trials to treatsupport patientsother whoSMA remainpatient onpopulations, thesuch as our Phase 12 DRAGONOPAL clinical trial, and 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 cardiometabolicanti-myostatin program, including the close out activities for our Phase 2 EMBRAZE proof-of-concept trial of apitegromab and our preclinicalPhase program,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.

WeBased on our current operating model, we expect that our existing cash, cash equivalents, marketable securities and cash available (see Note 18) to us will enable us to fund our operating expenses and capital expenditure requirements into the fourth quarter of 2026.2027. 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 research, testing, manufacturing, labeling, approval, sale, import, export, marketing, promotion and distribution of drug products, including biologics, are subject to extensive regulation by the FDA in the U.S. and other regulatory authorities outside the U.S. We are not permitted to market any biological product in the U.S. until we receive a biologics license from the FDA. Prior to submitting the BLA to the U.S. FDA in January 2025 and submitting the MAA to the EMA in March 2025 for apitegromab as a treatment for patients with SMA, we had not submitted a BLA to the FDA or MAA to the EMA or similar marketing application to comparable foreign authorities. A BLA must include extensive preclinical and clinical data and supporting information to establish that the product candidate is safe, pure and potent for each desired indication. FDA, EC or comparable foreign regulatory authorities’ approval of a new biologic or drug generally requires data from one or more adequate and well-controlled pivotal Phase 3 clinical trials of the biologic or drug in the relevant patient population. The FDA, EMA or comparable foreign regulatory authorities may disagree with the design or implementation of our clinical trials or our analysis or interpretation of data from preclinical studies or clinical trials, the results of our clinical trials may not meet the level of statistical significance or amount of data required for approval, regulatory authorities may not agree with the statistical methods we used to evaluate our clinical data, or we may be unable to demonstrate that apitegromab’s clinical and other benefits outweigh its safety risks. Even if the FDA, EMA, or other regulatory authorities were to grant approval for apitegromab in SMA, one or more of these regulatory authorities may determine that the approval should be limited to a subset b of SMA patients, which could restrict the commercial potential of apitegromab in SMA. A BLA to the FDA or MAA to the EMA must also include significant information regarding the chemistry, manufacturing, and controls for the product, and the manufacturing facilities must complete a successful pre-license inspection as well as certain key clinical sites conducting our clinical trials. The FDA, EMA or comparable foreign regulatory authorities may fail to approve the manufacturing processes or facilities of third-party manufacturers with which we contract for clinical and commercial supplies.

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 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 AgencyFDA 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 iswas expected to initiateinitiated in mid-2026.the second quarter of 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.

We have incurred significant operating losses since inception. Our net losses were $105.5$215.4 million for the threesix months ended MarchJune 31,30, 2026. As of MarchJune 31,30, 2026, we had an accumulated deficit of $1.4$1.5 billion. We expect to continue to incur significant expenses and operating losses for the foreseeable future in performing our ongoing activities, as we:

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.

Comparison of the Three Months Ended MarchJune 31,30, 2026 and 2025

The following table summarizes our results of operations for the three months ended MarchJune 31,30, 2026 and 2025 (in thousands, except percentages):

Research and development expense was $51.8$58.2 million and $48.7$62.4 million for the three months ended MarchJune 31,30, 2026 and 2025, respectively, ana increasedecrease of $3.1$4.2 million or 6.4%.6.7%. The following table summarizes our research and development expense for the three months ended MarchJune 31,30, 2026 and 2025 (in thousands, except percentages):

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

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 expense was $50.2$50.7 million and $28.4$49.7 million for the three months ended MarchJune 31,30, 2026 and 2025, respectively, an increase of $21.8$1.0 million or 76.7%.1.9%. The total increase was primarily driven by investments in infrastructure to support commercial launch readiness for apitegromab, including an increase of approximately $11.5$9.3 million in employee-related costs including salaries, bonus, benefits and payroll taxes related to increased headcount, an increase of $2.3$2.2 million in non-cash equity-basedequity based compensation expense related to increased headcount,expense, an increase of approximately $7.2$1.7 million in professional service fees and an increase of approximately $0.8$0.3 million in facility and other costs. The increase in headcount is partially associated with the hiring of our commercial and field-facing teams. These increases were partially offset by a decrease in costs associated with our leadership transition in 2025, including $8.6 million in non-cash equity-based compensation expense and $2.0 million in bonuses, as well as an overall decrease of $1.9 million in severance related costs. 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.

The change in other income (expense), net was primarily attributable to ourinterest lossexpense incurred on extinguishmentour debt facility, including amortization of debt,debt discount and debt issuance costs, partially offset by an increase in interest income earned due to higher average balances in our cash, cash equivalents and marketable securities.

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 prior research collaborationscollaborations, prior issuances of debt 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 MarchJune 31,30, 2026 and December 31, 2025 (in thousands):

During the threesix months ended MarchJune 31,30, 2026, our cash, cash equivalents and marketable securities balance increased by $112.4$124.5 million. The change was primarily due to proceeds from our debt facility, sales under our ATM program and the exercises of stock options,options and warrants, 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 effortsefforts, invested in building the infrastructure to support the commercialization of apitegromab 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 threesix months ended MarchJune 31,30, 2026, we sold 2,576,2993,543,692 shares of our common stock under the ATM program, generating net proceeds of $111.8$160.8 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 “ExistingOxford 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 ExistingOxford Loan Agreement with Oxford and upon such repayment, terminated the ExistingOxford 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 ExistingOxford Loan Agreement. As a result of the termination, all credit commitments under the ExistingOxford Loan Agreement were terminated and all security interests and guarantees executed in connection with the ExistingOxford 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 threesix months ended MarchJune 31,30, 2026, 6,804,082 of the Company’s pre-funded warrants were exercised. As of MarchJune 31,30, 2026, the Company had 10,558,065 pre-funded warrants outstanding.