SLDB

- Duchenne (SGT-003): SGT-003 has been generally well tolerated in the Phase 1/2 INSPIRE DUCHENNE clinical trial, with 53 participants dosed as of August 4, 2026 - - Solid expects to meet with the FDA in late Q4 2026 to discuss the SGT-003 data package and to seek guidance on a potential accelerated approval pathway for SGT-003 - - Initiation of dosing in the Phase 3 IMPACT DUCHENNE placebo-controlled, randomized, double-blind clinical trial commenced in Q2 2026 - - Friedreich’s Ataxia (SGT-212): Continued participant screening and enrollment is underway in the Phase 1b FALCON clinical trial; SGT-212 has been well tolerated in the two participants dosed as of August 4, 2026 - - Capital Position: Cash, cash equivalents and available-for-sale securities of $377.7 million at June 30, 2026; the Company’s cash runway is anticipated to support late-stage development and early pipeline opportunities into mid-2028 - CHARLESTOWN, Mass., Aug. 06, 2026 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. (Nasdaq: SLDB) (the “Company” or “Solid”), a life sciences company developing precision genetic medicines for neuromuscular and cardiac diseases, today reported financial results for the second quarter ended June 30, 2026, and provided a business update. Bo Cumbo, President and CEO of Solid Biosciences, stated: “Our progress in the first half of 2026 positions us for continued momentum as we approach multiple key clinical and regulatory milestones across our Duchenne, Friedreich’s ataxia and broader precision genetic medicine platform over the next several quarters. In Duchenne, we continue to have confidence in SGT-003’s safety profile, which is achieved using a low-burden, steroid-only immunomodulation regimen. We are also highly encouraged by the strength of the biomarker data we have generated to date, which demonstrates promising biologic activity. As we prepare to analyze 12-month clinical data from initial participants in the INSPIRE DUCHENNE trial, we gain an important opportunity to evaluate the relationship between these biologic signals and clinical outcomes. We look forward to continued engagement with the FDA as we work with urgency to evaluate a potential accelerated approval pathway for SGT-003.” Mr. Cumbo continued, “In FA, we continue to progress SGT-212 with two participants dosed in the FALCON clinical trial, and we look forward to sharing initial data in the first quarter of 2027, which will help inform future development pathways as we aim to bring SGT-212 rapidly to the FA patient community.” Company Updates Neuromuscular PipelineSGT-003 Next-Generation Duchenne Muscular Dystrophy (Duchenne) Program SGT-003 has been well tolerated in the 53 participants dosed in the Phase 1/2 INSPIRE DUCHENNE clinical trial as of August 4, 2026. Solid plans to meet with the FDA late in the fourth quarter of 2026 to discuss the INSPIRE DUCHENNE SGT-003 data package and to seek guidance on a potential accelerated approval pathway for SGT-003; the Company expects to provide an update as discussions progress. As announced on May 7, 2026, the Company reported that the first participant was dosed in the Phase 3 IMPACT DUCHENNE placebo-controlled, randomized, double-blind clinical trial. Clinical sites are currently active in Australia and Canada, with additional clinical site activations expected in the second half of 2026, subject to site initiation activities and regulatory clearances. SGT-212 for Friedreich’s ataxia (FA) SGT-212 has been well tolerated, with no treatment-related serious adverse events (TRSAEs) observed in the two participants dosed in the Phase 1b FALCON clinical trial as of August 4, 2026. Participant screening and enrollment remains ongoing, and the Company expects to report initial data in the first quarter of 2027, subject to participant enrollment. Cardiac PipelineSGT-501 for catecholaminergic polymorphic ventricular tachycardia (CPVT) Solid has activated clinical trial sites and commenced participant screening for the Phase 1b ARTEMIS clinical trial. Solid expects to dose the first participant in the second half of 2026, with initial safety data anticipated in the first half of 2027, subject to participant enrollment. Platform Technologies Solid has executed more than 50 agreements, including licenses, with corporations, institutions and academic labs for the use of POLARIS-101™, the Company’s next-generation, muscle-tropic capsid used in SGT-003. In July, Solid executed a license agreement with Addgene for POLARIS-101™. Addgene is one of the largest global plasmid repositories and has been a pioneer in accelerating research and discovery by improving access to high-quality scientific research materials. Under the terms of the agreement, the Company has granted Addgene a non-exclusive worldwide license to provide access to POLARIS-101™ through Addgene’s curated online catalog of materials. Second Quarter 2026 Financial Highlights Cash Position: Solid had $377.7 million in cash, cash equivalents and available-for-sale securities as of June 30, 2026, compared to $187.9 million as of December 31, 2025. The Company expects that its existing cash, cash equivalents, and available-for-sale securities will be sufficient to fund its operational runway into mid-2028. At-the-Market (ATM) Proceeds: The $377.7 million cash position at June 30, 2026, is inclusive of $60.8 million in net proceeds generated from ATM sales during the six months ended June 30, 2026. The Company generated an additional $15.7 million in net proceeds from ATM sales after June 30, 2026. Research and Development (R&D) Expenses: R&D expenses for the second quarter of 2026 were $44.3 million, compared to $32.4 million for the second quarter of 2025. The increase of $11.9 million in research and development expenses was primarily due to a $12.2 million increase in costs for SGT-003 primarily related to manufacturing and clinical costs, a $3.2 million increase in personnel related expenses, and a $1.2 million increase in costs for SGT-212 primarily related to clinical and research costs, partially offset by a $2.2 million decrease in costs for SGT-601 related to lower manufacturing and research costs, a $1.4 million decrease in external expenses primarily related to laboratory supplies, and a $1.3 million decrease in costs for SGT-501 primarily related to lower license payments and research costs. General and Administrative (G&A) Expenses: G&A expenses for the second quarter of 2026 were $13.1 million, compared to $9.3 million for the second quarter of 2025. The increase of $3.8 million was primarily due to a $2.6 million increase in personnel related costs, a $0.5 million increase in business development costs, a $0.4 million increase in equipment costs, and a $0.3 million increase in consulting services. Net Loss: Net loss for the second quarter of 2026 was $54.8 million, compared to a net loss of $39.5 million for the second quarter of 2025. About SGT-003 SGT-003 is an investigational gene therapy containing a novel microdystrophin construct and a proprietary, next-generation capsid, POLARIS-101™ (formerly known as AAV-SLB101), which was rationally designed to target integrin receptors, and has shown enhanced cardiac and skeletal muscle transduction with decreased liver targeting in data from the Phase 1/2 INSPIRE DUCHENNE clinical trial and in nonclinical studies. SGT-003’s microdystrophin construct uniquely includes the R16/17 domains, which localize nNOS to the muscle. Nonclinical studies have shown that nNOS can improve blood flow to the muscle thereby reducing muscle breakdown from ischemia and muscle fatigue. Together, these design features suggest that SGT-003 could be a potential best-in-class investigational gene therapy for the treatment of Duchenne. About the SGT-003 Development Program The SGT-003 clinical development program consists of two multinational clinical trials – the Phase 1/2 INSPIRE DUCHENNE trial and the Phase 3 IMPACT DUCHENNE trial – which together were designed to generate a comprehensive data package to support potential global regulatory authorizations. INSPIRE DUCHENNE is a first-in-human, open-label, single-dose, multicenter Phase 1/2 clinical trial evaluating the safety, tolerability and efficacy of a single dose of SGT-003 in pediatric participants with a genetically confirmed Duchenne diagnosis. The trial is being conducted at clinical sites in the United States, Canada, the United Kingdom and Italy. IMPACT DUCHENNE is a Phase 3 placebo-controlled, randomized, double-blind clinical trial evaluating the efficacy of a single dose of SGT-003 in ambulatory participants with a genetically confirmed Duchenne diagnosis. Clinical trial sites are currently active in Australia and Canada, with additional clinical site activations expected in the second half of 2026, subject to site initiation activities and regulatory clearances. About SGT-212 SGT-212 is a recombinant AAV-based gene replacement therapy for Friedreich’s ataxia (FA) designed to deliver full-length human frataxin (FXN) via a dual route of administration: intradentate nucleus (IDN) infusion, using an FDA-approved neurosurgical device in a stereotactic, precision MRI-guided technique, followed by an intravenous (IV) infusion, with the intent to increase therapeutic FXN levels in the cerebellar dentate nuclei, cardiomyocytes and other systemic tissues. Targeted delivery to the dentate nuclei will be confirmed in real time via MRI. Restoration of FXN levels is expected to repair the underlying mitochondrial dysfunction in neurons and cardiomyocytes to address neurologic, cardiac and systemic manifestations of the disease. About the FALCON Clinical Trial FALCON is a first-in-human, open-label, multi-center Phase 1b clinical trial designed to evaluate the safety and tolerability of SGT-212 in participants aged 18-40 who have been diagnosed with FA. FALCON is being conducted in the United States. About Solid Biosciences Solid Biosciences is a precision genetic medicine company focused on advancing a portfolio of gene therapy candidates targeting rare neuromuscular and cardiac diseases, including SGT-003 for Duchenne muscular dystrophy (Duchenne), SGT-212 for Friedreich’s ataxia (FA), SGT-501 for catecholaminergic polymorphic ventricular tachycardia (CPVT), SGT-601 for TNNT2-mediated dilated cardiomyopathy and additional fatal, genetic cardiac diseases. The Company is also focused on developing innovative libraries of genetic regulators and other enabling technologies with promising potential to significantly impact gene therapy delivery cross-industry. Solid is advancing its diverse pipeline and delivery platform in the pursuit of uniting experts in science, technology, disease management, and care. Patient-focused and founded by those directly impacted by Duchenne, Solid’s mission is to improve the daily lives of patients living with devastating rare diseases. For more information, please visit www.solidbio.com and follow us on LinkedIn at Solid Biosciences and X at @Solid_Bio. Cautionary Note Regarding Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding future expectations, plans and prospects for the company; the ability to successfully achieve and execute on the company’s goals; anticipated benefits of SGT-003, SGT-212, SGT-501 and other pre-clinical programs and technologies; strategies and expectations for the company’s SGT-003, SGT-212, SGT-501, SGT-601 and other pre-clinical programs and technologies; expectations for planned site activation, planned enrollment, planned regulatory interactions and the potential approval pathways for SGT-003, SGT-212 and SGT-501; the cash runway of the company and the sufficiency of the Company’s cash, cash equivalents, and available-for-sale securities to fund its operations; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “working” and similar expressions. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the company’s ability to advance SGT-003, SGT-212, SGT-501, SGT-601 and other preclinical programs, capsid libraries and other enabling technologies on the timelines expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; replicate in clinical trials positive results found in preclinical studies and early-stage clinical trials of the company’s product candidates; manufacture sufficient quantities of our drug product in a timely manner and maintain adequate supply to support our clinical development and potential commercialization; obtain, maintain or protect intellectual property rights related to its product candidates; replicate preliminary or interim data from clinicals trials in the final data of such trials; compete successfully with other companies that are seeking to develop Duchenne, FA, CPVT and other neuromuscular and cardiac treatments and gene therapies; manage expenses; and raise the substantial additional capital needed, on the timeline necessary, to continue development of SGT-003, SGT-212, SGT-501, SGT-601 and other candidates; achieve its other business objectives and continue as a going concern. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in the company’s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the company’s views as of the date hereof and should not be relied upon as representing the company’s views as of any date subsequent to the date hereof. The company anticipates that subsequent events and developments will cause the company's views to change. However, while the company may elect to update these forward-looking statements at some point in the future, the company specifically disclaims any obligation to do so. Solid Biosciences Investor Contact:Nicole AndersonSenior Director, Investor Relations and Corporate CommunicationsSolid Biosciences [email protected]

- Duchenne (SGT-003): First participant dosed in the Phase 3 IMPACT DUCHENNE clinical trial, receipt of positive opinion on the Company’s Pediatric Investigation Plan from the European Medicines Agency and Orphan drug designation from the European Commission mark important advancements in the program’s global development - - Continued progress achieved across the SGT-003 development program, including dosing of 47 participants in Phase 1/2 INSPIRE DUCHENNE clinical trial, and ongoing engagement with the FDA for guidance on a potential accelerated approval pathway for SGT-003 - - Friedreich’s Ataxia (SGT-212): Second participant dosed in the Phase 1b FALCON clinical trial; SGT-212 has been well tolerated with no serious adverse events observed - - CPVT (SGT-501): Company anticipates dosing the first participant in the Phase 1b ARTEMIS clinical trial evaluating SGT-501 for the treatment of catecholaminergic polymorphic ventricular tachycardia (CPVT) in H2 2026 - - Capital Position: Cash, cash equivalents and available-for-sale securities of $380.7 million at March 31, 2026; the Company’s cash runway is anticipated to extend into H1 2028 - CHARLESTOWN, Mass., May 12, 2026 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. (Nasdaq: SLDB) (the “Company” or “Solid”), a life sciences company developing precision genetic medicines for neuromuscular and cardiac diseases, today reported financial results for the first quarter ended March 31, 2026, and provided a business update. Bo Cumbo, President and CEO of Solid Biosciences, stated: “The beginning of 2026 has seen Solid make meaningful strides as we continue to execute across our pipeline and platform development efforts. In Duchenne, we dosed the first participant in our Phase 3 IMPACT DUCHENNE clinical trial for SGT-003 and received Orphan drug designation from the European Commission, representing important milestones in the program’s global advancement. We also continue to enroll and dose participants in the Phase 1/2 INSPIRE DUCHENNE clinical trial, which has maintained a consistent and encouraging safety and tolerability profile. “As we progress through the year, we look forward to ongoing engagement with the FDA, focusing on our thoughtful approach to generating rigorous, well-controlled clinical data through our integrated, multi-country, multi-trial development program. We recognize the significant unmet need in Duchenne and see the potential for our novel therapy to offer a differentiated treatment option for families living with this unrelenting disease. “In parallel, we are working closely with the UK Medicines and Healthcare products Regulatory Agency (MHRA) under our ILAP Innovation Passport and recently received a positive opinion from the European Medicines Agency (EMA) on our Pediatric Investigation Plan, reflecting our efforts to inform potential development and regulatory pathways outside of the United States. We continue to build the organizational and geographic foundations to support future global development and have made the decision to establish dedicated ex-U.S. leadership with the planned addition of a Head of Europe. “Beyond Duchenne, we have now dosed two participants in the Phase 1b FALCON clinical trial of our Friedreich’s ataxia gene therapy program, SGT-212, which has been well tolerated by both participants. While still early, we are encouraged by initial clinical observations and remain focused on advancing the program thoughtfully as data emerge. Across our company, we continue to execute our plan and advance our programs with the fiscal discipline and operational rapidity required to deliver meaningful outcomes to patients and our shareholders,” Mr. Cumbo concluded. Company Updates Neuromuscular Pipeline SGT-003 Next-Generation Duchenne Muscular Dystrophy (Duchenne) Program As announced on May 7, 2026, the Company reported that the first participant was dosed in IMPACT DUCHENNE, the Phase 3 multi-country, placebo-controlled, randomized, double-blind, clinical trial. Solid has received a positive opinion from the European Medicines Agency’s Paediatric Committee on its Pediatric Investigation Plan (PIP), establishing alignment on its pediatric development framework for SGT-003 in Europe. The Company announced on April 28, 2026, that SGT-003 had been granted Orphan drug designation by the European Commission (EC). SGT-003 has received numerous regulatory designations from global health authorities, including the Innovation Passport designation under the new U.K. Innovation License and Access Pathway program and Fast Track, Orphan Drug and Rare Pediatric Disease designations from the U.S. Food and Drug Administration. SGT-003 continued to be generally well tolerated in the 47 participants dosed in the INSPIRE DUCHENNE trial as of May 11, 2026. The 47th participant was dosed on May 8, 2026. The Company reported positive interim data from the ongoing Phase 1/2 INSPIRE DUCHENNE clinical trial on March 11, 2026, which continued to suggest differentiated clinical, safety and tolerability profiles. The Company announced on February 9, 2026, that it had reached alignment with the U.S. Food and Drug Administration (FDA) on the overall study design for IMPACT DUCHENNE. Solid expects to continue discussions with the FDA to receive guidance on a potential accelerated approval pathway for SGT-003 and expects to provide an update as discussions progress. SGT-212 for Friedreich’s ataxia (FA) Two participants have been dosed in the Phase 1b FALCON clinical trial, and SGT-212 has been well tolerated as of May 11, 2026, with no serious adverse events observed. Participant dosing remains ongoing with initial data expected by year-end 2026, subject to participant enrollment. Cardiac Pipeline SGT-501 for catecholaminergic polymorphic ventricular tachycardia (CPVT) Clinical trial sites have been activated and participant screening is underway for the Phase 1b ARTEMIS trial. The first participant is anticipated to be dosed in the second half of 2026, with initial safety data anticipated in the first half of 2027, subject to participant enrollment. Platform Technologies – Capsids In March 2026, AAV-SLB101, the Company’s next-generation, muscle-tropic capsid used in SGT-003, was renamed POLARIS-101™. Solid has executed more than 50 agreements, including licenses, with corporations, institutions and academic labs for the use of POLARIS-101™. First Quarter 2026 Financial Highlights Cash Position: Solid had $380.7 million in cash, cash equivalents, and available-for-sale securities as of March 31, 2026, compared to $187.9 million as of December 31, 2025. The Company expects that its existing cash, cash equivalents, and available-for-sale securities will be sufficient to fund its operational runway into the first half of 2028. Research and Development (R&D) Expenses: R&D expenses for the first quarter of 2026 were $46.1 million, compared to $30.9 million for the first quarter of 2025. The increase of $15.2 million in research and development expenses was primarily due to a $13.6 million increase in costs for SGT-003 primarily related to manufacturing and clinical costs, a $3.3 million increase in personnel related expenses, a $2.5 million increase in costs for SGT-212 primarily related to clinical costs and license and milestone payments, and a $0.4 million increase in external expenses primarily related to consulting and professional services, partially offset by a $3.1 million decrease in costs for SGT-501 primarily related to lower manufacturing and research costs, and a $1.7 million decrease in costs for SGT-601 related to lower manufacturing and research costs. General and Administrative (G&A) Expenses: G&A expenses for the first quarter of 2026 were $11.2 million, compared to $9.1 million for the first quarter of 2025. The increase of $2.0 million was primarily related to a $1.5 million increase in personnel related costs, a $0.5 million increase in consulting services, and a $0.4 million increase in equipment costs, partially offset by a $0.5 million decrease in legal fees. Net Loss: Net loss for the first quarter of 2026 was $56.7 million, compared to a net loss of $39.3 million for the first quarter of 2025. About SGT-003 SGT-003 is an investigational gene therapy containing a novel microdystrophin construct and a proprietary, next-generation capsid, POLARIS-101™ (formerly known as AAV-SLB101), which was rationally designed to target integrin receptors, and has shown enhanced cardiac and skeletal muscle transduction with decreased liver targeting in data from the Phase 1/2 INSPIRE DUCHENNE clinical trial and in nonclinical studies. SGT-003’s microdystrophin construct uniquely includes the R16/17 domains, which localize nNOS to the muscle. Nonclinical studies have shown that nNOS can improve blood flow to the muscle thereby reducing muscle breakdown from ischemia and muscle fatigue. Together, these design features suggest that SGT-003 could be a potential best-in-class investigational gene therapy for the treatment of Duchenne. About the SGT-003 Development Program The SGT-003 clinical development program consists of two multinational clinical trials – the Phase 1/2 INSPIRE DUCHENNE trial and the Phase 3 IMPACT DUCHENNE trial – which together were designed to generate a comprehensive data package to support potential global regulatory authorizations. INSPIRE DUCHENNE is a first-in-human, open-label, single-dose, multicenter Phase 1/2 clinical trial evaluating the safety, tolerability and efficacy of a single dose of SGT-003 in pediatric participants with a genetically confirmed Duchenne diagnosis. The trial is being conducted at clinical sites in the United States, Canada, the United Kingdom and Italy. IMPACT DUCHENNE is a Phase 3 placebo-controlled, randomized, double-blind clinical trial evaluating the efficacy of a single dose of SGT-003 in ambulatory participants with a genetically confirmed Duchenne diagnosis. Clinical trial sites are currently active in Australia and Canada and additional clinical site activations in the UK and US are expected in the second half of 2026, with sites in the EU anticipated to follow, subject to regulatory clearances. About SGT-212 SGT-212 is a recombinant AAV-based gene replacement therapy for Friedreich’s ataxia (FA) designed to deliver full-length human frataxin (FXN) via a dual route of administration: intradentate nucleus (IDN) infusion, using an FDA-approved neurosurgical device in a stereotactic, precision MRI-guided technique, followed by an intravenous (IV) infusion, with the intent to increase therapeutic FXN levels in the cerebellar dentate nuclei, cardiomyocytes and other systemic tissues. Targeted delivery to the dentate nuclei will be confirmed in real time via MRI. Restoration of FXN levels is expected to repair the underlying mitochondrial dysfunction in neurons and cardiomyocytes to address neurologic, cardiac and systemic manifestations of the disease. About the FALCON Clinical Trial FALCON is a first-in-human, open-label, multi-center Phase 1b clinical trial designed to evaluate the safety and tolerability of SGT-212 in participants aged 18-40 who have been diagnosed with FA. FALCON is being conducted in the United States. About Solid Biosciences Solid Biosciences is a precision genetic medicine company focused on advancing a portfolio of gene therapy candidates targeting rare neuromuscular and cardiac diseases, including SGT-003 for Duchenne muscular dystrophy (Duchenne), SGT-212 for Friedreich’s ataxia (FA), SGT-501 for catecholaminergic polymorphic ventricular tachycardia (CPVT), SGT-601 for TNNT2-mediated dilated cardiomyopathy and additional fatal, genetic cardiac diseases. The Company is also focused on developing innovative libraries of genetic regulators and other enabling technologies with promising potential to significantly impact gene therapy delivery cross-industry. Solid is advancing its diverse pipeline and delivery platform in the pursuit of uniting experts in science, technology, disease management, and care. Patient-focused and founded by those directly impacted by Duchenne, Solid’s mission is to improve the daily lives of patients living with devastating rare diseases. For more information, please visit www.solidbio.com. Cautionary Note Regarding Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding future expectations, plans and prospects for the company; the ability to successfully achieve and execute on the company’s goals; anticipated benefits of SGT-003, SGT-212, SGT-501and other pre-clinical programs and technologies; strategies and expectations for the company’s SGT-003, SGT-212, SGT-501, SGT-601 and other pre-clinical programs and technologies; expectations for planned site activation, planned enrollment, planned regulatory interactions and the potential approval pathways for SGT-003, SGT-212 and SGT-501; the cash runway of the company and the sufficiency of the Company’s cash, cash equivalents, and available-for-sale securities to fund its operations; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “working” and similar expressions. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the company’s ability to advance SGT-003, SGT-212, SGT-501, SGT-601 and other preclinical programs, capsid libraries and other enabling technologies on the timelines expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; replicate in clinical trials positive results found in preclinical studies and early-stage clinical trials of the company’s product candidates; manufacture sufficient quantities of our drug product in a timely manner and maintain adequate supply to support our clinical development and potential commercialization; obtain, maintain or protect intellectual property rights related to its product candidates; replicate preliminary or interim data from clinicals trials in the final data of such trials; compete successfully with other companies that are seeking to develop Duchenne, FA, CPVT and other neuromuscular and cardiac treatments and gene therapies; manage expenses; and raise the substantial additional capital needed, on the timeline necessary, to continue development of SGT-003, SGT-212, SGT-501, SGT-601 and other candidates; achieve its other business objectives and continue as a going concern. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in the company’s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the company’s views as of the date hereof and should not be relied upon as representing the company’s views as of any date subsequent to the date hereof. The company anticipates that subsequent events and developments will cause the company's views to change. However, while the company may elect to update these forward-looking statements at some point in the future, the company specifically disclaims any obligation to do so. Solid Biosciences Investor Contact: Nicole Anderson Senior Director, Investor Relations and Corporate Communications Solid Biosciences Inc. [email protected]

- Duchenne (SGT-003): Positive interim Phase 1/2 INSPIRE DUCHENNE data reported at the 2026 MDA Annual Meeting continued to suggest differentiated clinical, safety and tolerability profiles; SGT-003 has been generally well tolerated in the 41 participants dosed as of March 18, 2026 - - Company anticipates dosing the first participant in the Phase 3 IMPACT DUCHENNE trial in April 2026; additional meetings planned with FDA in H1 2026 for guidance on a potential accelerated approval pathway for SGT-003 - - Friedreich’s Ataxia (SGT-212): First participant dosed in the Phase 1b FALCON trial; SGT-212 has been well tolerated with no treatment-related adverse events - - CPVT (SGT-501): Clinical sites activated for Phase 1b ARTEMIS first-in-human clinical trial evaluating SGT-501 for the treatment of catecholaminergic polymorphic ventricular tachycardia (CPVT); first participant dosing expected in Q2 2026 - - Strong Capital Position: Cash, cash equivalents and available-for-sale securities of $187.9 million at December 31, 2025; in March 2026, the Company completed a $240 million private placement; the Company’s cash runway is anticipated to extend into H1 2028 - CHARLESTOWN, Mass., March 19, 2026 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. (Nasdaq: SLDB) (the “Company” or “Solid”), a life sciences company developing precision genetic medicines for neuromuscular and cardiac diseases, today reported financial results for the fourth quarter and full year ended December 31, 2025, and provided a business update. Bo Cumbo, President and CEO of Solid Biosciences, commented, “We continue to build momentum across our portfolio, highlighted by updated interim INSPIRE DUCHENNE data presented at MDA, positive feedback from our FDA Type C meeting on the Phase 3 IMPACT DUCHENNE trial design for SGT-003, the dosing of our first participant in the FALCON trial for SGT-212 and the completion of an oversubscribed $240 million private placement. Together, these achievements strengthen our operational and financial foundation and position Solid to deliver on the promise of our science and improve the daily lives of people living with devastating rare diseases. “Looking to the year ahead, we expect several important milestones, including continued engagement with the FDA to seek guidance on a potential accelerated approval pathway for SGT-003 for the treatment of Duchenne, dosing the first participant in the Phase 3 IMPACT DUCHENNE trial for SGT-003 and the Phase 1b ARTEMIS trial for SGT-501, and further progressing each of our clinical stage programs. With multiple anticipated regulatory and clinical milestones ahead, we believe 2026 will be a transformational year for Solid.” Company Updates Neuromuscular Pipeline SGT-003 Next-Generation Duchenne Muscular Dystrophy (Duchenne) Program SGT-003 continued to be generally well tolerated in the 41 participants dosed as of March 18, 2026; SGT-003 is administered using a lower-burden, steroid-only prophylactic immunomodulation regimen. As announced on March 11, 2026, the Company reported positive interim data from the ongoing Phase 1/2 INSPIRE DUCHENNE clinical trial. Updated interim data provided continuing evidence suggesting a disease-relevant treatment effect. Observed robust microdystrophin expression and restoration of key components of the dystrophin-associated protein complex (DAPC), including beta-sarcoglycan and neuronal nitric oxide synthase (nNOS). Observed improvements across an extensive panel of muscle integrity biomarkers. Observed stabilization and improvement in cardiac function as measured by left ventricular ejection fraction (LVEF). Participant dosing remains ongoing in the INSPIRE DUCHENNE trial. The Company announced on February 9, 2026, that it had reached alignment with the FDA on the overall study design for IMPACT DUCHENNE, Solid’s randomized, double-blind, placebo-controlled Phase 3 clinical trial of SGT-003. Participant screening is underway and the Company anticipates dosing the first participant in the IMPACT DUCHENNE trial in April 2026. In the first half of 2026, the Company plans to have additional meetings with the FDA to receive guidance on a potential accelerated approval pathway for SGT-003. SGT-212 for Friedreich’s ataxia (FA) As announced on January 12, 2026, the first participant was dosed in the Phase 1b FALCON clinical trial evaluating SGT-212 for the treatment of FA. SGT-212 was well tolerated with no treatment-related adverse events as of March 18, 2026. Participant dosing remains ongoing with initial data expected in the second half of 2026, subject to participant enrollment. Cardiac Pipeline SGT-501 for Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) Clinical trial sites have been activated and participant screening is underway for the Phase 1b ARTEMIS trial. The first participant is expected to be dosed in the second quarter of 2026, with initial safety data anticipated in the second half of 2026, subject to participant enrollment. Platform Technologies – Capsids In March 2026, AAV-SLB101, the Company’s next-generation, muscle-tropic capsid used in SGT-003, was renamed POLARIS-101™. Solid has executed 50+ agreements, including licenses, with corporations, institutions and academic labs for the use of POLARIS-101™. Oversubscribed $240 Million Private Placement On March 6, 2026, the Company announced that it had entered into a securities purchase agreement with a select group of institutional accredited investors for a private placement of approximately $240 million in gross proceeds. Solid expects to use net proceeds from the private placement to fund ongoing pipeline development programs, business development activities, and for working capital and other general corporate purposes. Fourth Quarter and Full-Year 2025 Financial Highlights Cash Position: Solid had $187.9 million in cash, cash equivalents, and available-for-sale securities as of December 31, 2025, compared to $148.9 million as of December 31, 2024. Including the net proceeds from the $240 million private placement, the Company expects that its existing cash, cash equivalents, and available-for-sale securities will be sufficient to fund its operational runway into the first half of 2028. Research and Development (R&D) Expenses: R&D expenses for the fourth quarter of 2025 were $38.1 million, compared to $30.8 million for the fourth quarter of 2024. Research and development expenses for the full year ended December 31, 2025, were $140.3 million, compared to $96.4 million for the full year ended December 31, 2024. The increase of $43.9 million in research and development expenses was primarily due to a $43.8 million increase in costs for SGT-003 related to manufacturing and clinical costs, a $10.3 million increase in personnel related expenses, a $5.0 million increase in costs for SGT-601 primarily related to manufacturing and research costs, partially offset by a net decrease of $7.6 million in costs for SGT-501 related to lower manufacturing and study costs partially offset by an increase in clinical, regulatory and licensing fees, and a $6.0 million decrease in costs for other development programs. General and Administrative (G&A) Expenses: G&A expenses for the fourth quarter of 2025 were $11.3 million, compared to $9.1 million for the fourth quarter of 2024. General and administrative expenses for the full year ended December 31, 2025, were $38.9 million, compared to $33.3 million for the full year ended December 31, 2024. The increase of $5.6 million was primarily related to a $6.1 million increase in personnel related costs and a $0.6 million increase in information technology support and services, partially offset by a $1.1 million decrease in general legal fees. Net Loss: Net loss for the fourth quarter of 2025 was $49.8 million, compared to a net loss of $42.6 million for the fourth quarter of 2024. Net loss for the full year ended December 31, 2025, was $174.3 million, compared to a net loss $124.7 million for the full year ended December 31, 2024. About SGT-003 SGT-003 is an investigational gene therapy containing a differentiated microdystrophin construct and a proprietary, next-generation capsid, POLARIS-101™ (formerly known as AAV-SLB101), which was rationally designed to target integrin receptors, and has shown enhanced cardiac and skeletal muscle transduction with decreased liver targeting in data from the Phase 1/2 INSPIRE DUCHENNE clinical trial and in nonclinical studies. SGT-003’s microdystrophin construct uniquely includes the R16/17 domains, which localize nNOS to the muscle. Nonclinical studies have shown that nNOS can improve blood flow to the muscle thereby reducing muscle breakdown from ischemia and muscle fatigue. Together, these design features suggest that SGT-003 could be a potential best-in-class investigational gene therapy for the treatment of Duchenne. About the INSPIRE DUCHENNE Clinical Trial INSPIRE DUCHENNE is a first-in-human, open-label, single-dose, multicenter Phase 1/2 clinical trial to evaluate the safety, tolerability and efficacy of SGT-003 in pediatric participants with a genetically confirmed Duchenne diagnosis with a documented dystrophin gene mutation. INSPIRE DUCHENNE is a multinational trial designed to enroll participants in the United States, Canada, the United Kingdom and Italy. About the IMPACT DUCHENNE Clinical Trial IMPACT DUCHENNE is a Phase 3 randomized, double-blind, placebo-controlled trial to evaluate the efficacy of a single dose of SGT-003 in ambulatory participants aged 7 to less than 12 with a genetically confirmed Duchenne diagnosis. IMPACT DUCHENNE is a multinational trial intended to support potential regulatory authorizations. About SGT-212 SGT-212 is a recombinant AAV-based gene replacement therapy for Friedreich’s ataxia (FA) designed to deliver full-length human frataxin (FXN) via a dual route of administration: intradentate nucleus (IDN) infusion, using an FDA-approved neurosurgical device in a stereotactic, precision MRI-guided technique, followed by an intravenous (IV) infusion, with the intent to increase therapeutic FXN levels in the cerebellar dentate nuclei, cardiomyocytes and other systemic tissues. Targeted delivery to the dentate nuclei will be confirmed in real time via MRI. Restoration of FXN levels is expected to repair the underlying mitochondrial dysfunction in neurons and cardiomyocytes to address neurologic, cardiac and systemic manifestations of the disease. About the FALCON Clinical Trial FALCON is a first-in-human, open-label, multi-center Phase 1b clinical trial designed to evaluate the safety and tolerability of SGT-212 in participants aged 18-40 who have been diagnosed with FA. FALCON is being conducted in the United States. About Solid Biosciences Solid Biosciences is a precision genetic medicine company focused on advancing a portfolio of gene therapy candidates targeting rare neuromuscular and cardiac diseases, including SGT-003 for Duchenne muscular dystrophy (Duchenne), SGT-212 for Friedreich’s ataxia (FA), SGT-501 for catecholaminergic polymorphic ventricular tachycardia (CPVT), SGT-601 for TNNT2-mediated dilated cardiomyopathy and additional fatal, genetic cardiac diseases. The Company is also focused on developing innovative libraries of genetic regulators and other enabling technologies with promising potential to significantly impact gene therapy delivery cross-industry. Solid is advancing its diverse pipeline and delivery platform in the pursuit of uniting experts in science, technology, disease management, and care. Patient-focused and founded by those directly impacted by Duchenne, Solid’s mission is to improve the daily lives of patients living with devastating rare diseases. For more information, please visit www.solidbio.com. Cautionary Note Regarding Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding future expectations, plans and prospects for the company; the ability to successfully achieve and execute on the company’s goals; anticipated benefits of SGT-003, SGT-212, SGT-501and other pre-clinical programs and technologies; strategies and expectations for the company’s SGT-003 program, SGT-212, SGT-501, SGT-601 and other pre-clinical programs and technologies; expectations for planned enrollment, planned regulatory interactions and the potential approval pathways for SGT-003, SGT-212 and SGT-501; the cash runway of the company and the sufficiency of the Company’s cash, cash equivalents, and available-for-sale securities to fund its operations; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “working” and similar expressions. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the company’s ability to advance SGT-003, SGT-212, SGT-501, SGT-601 and other preclinical programs, capsid libraries and other enabling technologies on the timelines expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; replicate in clinical trials positive results found in preclinical studies and early-stage clinical trials of the company’s product candidates; manufacture sufficient quantities of our drug product in a timely manner and maintain adequate supply to support our clinical development and potential commercialization; obtain, maintain or protect intellectual property rights related to its product candidates; replicate preliminary or interim data from clinicals trials in the final data of such trials; compete successfully with other companies that are seeking to develop Duchenne, FA, CPVT and other neuromuscular and cardiac treatments and gene therapies; manage expenses; and raise the substantial additional capital needed, on the timeline necessary, to continue development of SGT-003, SGT-212, SGT-501, SGT-601 and other candidates; achieve its other business objectives and continue as a going concern. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in the company’s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the company’s views as of the date hereof and should not be relied upon as representing the company’s views as of any date subsequent to the date hereof. The company anticipates that subsequent events and developments will cause the company's views to change. However, while the company may elect to update these forward-looking statements at some point in the future, the company specifically disclaims any obligation to do so. Solid Biosciences Investor Contact: Nicole Anderson Senior Director, Investor Relations and Corporate Communications Solid Biosciences Inc. [email protected] Media Contact: Glenn Silver FINN Partners [email protected]

Solid Biosciences (SLDB) reported updated “positive” interim data from the ongoing Phase 1/2 INSPIRE DUCHENNE clinical trial of SGT-003. The new data, including additional muscle biopsy, serum biomarker, cardiac function, and safety analyses, “add to a growing dataset that suggests the potential of the biological activity of SGT-003 microdystrophin therapy,” the company stated. The interim update was delivered in an oral presentation at the 2026 MDA Annual Meeting on March 11. “SGT-003 has been generally well tolerated in the 40 participants dosed as of March 11, 2026. The safety and tolerability profile observed in the INSPIRE DUCHENNE trial continued to be promising; SGT-003 is administered using a low-burden, steroid-only prophylactic immunomodulation regimen. The trial is being conducted at 15 clinical sites across the US, Canada, Italy and the United Kingdom and participant dosing remains ongoing. Microdystrophin transduction and expression levels, beta-sarcoglycan localization and nNOS activity were evaluated by biopsy in 20 participants (ages 1-10 years) at Day 90 and in 3 participants at Day 360. Results demonstrated robust mean vector copies per nucleus and microdystrophin expression as well as properly localized and restored beta-sarcoglycan-positive fibers and nNOS activity-positive fibers,” the company stated. Bo Cumbo, President and CEO of Solid Biosciences commented, “These data continue to suggest that SGT-003 may be having a disease-relevant treatment effect, with observed robust microdystrophin expression, restoration of key components of the dystrophin-associated protein complex suggesting a direct biologic correlate of dystrophin activity, and improvements across multiple biomarkers of muscle integrity. Together with the promising safety and tolerability profile, these interim results reinforce our confidence in the potential of SGT-003 to meaningfully impact the disease course of Duchenne. Duchenne continues to have an unmet medical need. We are pursuing guidance on a potential accelerated approval pathway for SGT-003 and look forward to continued engagement with the FDA as we work toward that goal. Our focus remains on urgently advancing SGT-003 to provide the Duchenne community with an additional therapeutic choice.” Unlock hedge fund-level data and powerful investing tools for smarter, sharper decisions Stay ahead of the market with the latest news and analysis and maximize your portfolio's potential Published first on TheFly – the ultimate source for real-time, market-moving breaking financial news. Try Now>> See Insiders’ Hot Stocks on TipRanks >> Read More on SLDB: Disclaimer & DisclosureReport an Issue Solid Biosciences trading halted, news pending Solid Biosciences Announces $240 Million Private Placement Financing Solid Biosciences prices 14.97M shares at $5.61 in private placement Solid Biosciences reaches FDA alignment on IMPACT DUCHENNE study design Reiterating Buy on Solid Biosciences: Conviction in Next‑Generation DMD Gene Therapy and Favorable Risk‑Reward

- Duchenne (SGT-003): 23 participants have been dosed in the INSPIRE DUCHENNE trial as of October 31, 2025; Solid expects to have dosed 30 participants in total by early 2026, then plans to meet with the FDA to discuss potential registrational pathways in H1 2026 - - SGT-003 has been generally well tolerated using a steroid-only prophylactic immunomodulation regimen; cardiac safety monitoring continued to show reduction in cardiac injury and early signals of cardiac function normalization - - Day 90 biopsy data from 10 treated participants (ages 5-10) showed all participants responded to treatment with mean microdystrophin expression of 58% by western blot, 58% by mass spectrometry, mean microdystrophin positive fibers of 51% by immunofluorescence, and mean beta-sarcoglycan positive fibers of 50% by immunofluorescence - - Strong statistical correlations observed between Day 90 microdystrophin expression levels and key components of the dystrophin-associated protein complex (DAPC), beta-sarcoglycan (r = 0.95) and nNOS (r = 0.95), demonstrated evidence of SGT-003-mediated DAPC restoration and concordant signals of muscle protection via reductions in CK levels (r = -0.78) - - Solid has activated the first clinical trial site and is currently screening participants for IMPACT DUCHENNE, a Phase 3 randomized, double-blind, placebo-controlled ex-U.S. clinical trial of SGT-003 - - FA (SGT-212): Solid has activated the first clinical trial site and is currently screening participants for FALCON, a Phase 1b first-in-human clinical trial evaluating SGT-212 for the treatment of Friedreich’s ataxia - - CPVT (SGT-501): Clinical trial site activation for ARTEMIS, a Phase 1b first-in-human clinical trial evaluating SGT-501 for the treatment of catecholaminergic polymorphic ventricular tachycardia expected in Q4 2025 - - Capsids (AAV-SLB101): Over 30 agreements including licenses executed with corporations, institutions, and academic labs for the use of AAV-SLB101 - - Cash: Company ended Q3 2025 with $236.1 million in cash, cash equivalents and available-for-sale securities; Solid has anticipated cash runway into H1 2027 - CHARLESTOWN, MA, Nov. 03, 2025 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. (Nasdaq: SLDB) (the “Company” or “Solid”), a life sciences company developing precision genetic medicines for neuromuscular and cardiac diseases, today reported financial results for the third quarter ended September 30, 2025, and announced positive new interim data from the Phase 1/2 INSPIRE DUCHENNE clinical trial. The Company also provided an update to the planned timing of its meeting with the U.S. Food and Drug Administration (FDA) to discuss potential registrational pathways, including accelerated approval pathways, for SGT-003. Bo Cumbo, President and CEO of Solid Biosciences commented, “The interim INSPIRE DUCHENNE data reported today strengthens our confidence in SGT-003’s therapeutic potential. From strong observed biological correlations of SGT-003 microdystrophin expression levels with properly localized restoration of key components of the dystrophin-associated protein complex to early evidence of cardiac function normalization, we are observing a clear and cascading effect in the human body, suggesting a coordinated, systemic response to treatment. We believe these interim data represent one of the most thorough early analyses of any Duchenne gene therapy to date. The quality and concurrence of these interim findings reinforce our conviction in SGT-003’s potential to translate molecular impact into meaningful clinical outcomes.” Gabriel Brooks, MD, Chief Medical Officer of Solid Biosciences commented, “We are gratified and encouraged by the interim data observed to date. SGT-003 has been generally well tolerated with a minimally burdensome, prophylactic immunomodulatory regimen consisting of steroids alone. Importantly, early data suggests stabilization and improvement in cardiac function, as evidenced by both reductions in elevated baseline serum cardiac troponin I levels and a normalization in left ventricular ejection fraction (LVEF). We look forward to monitoring these cardiac markers closely as potential key differentiators of SGT-003.” Mr. Cumbo continued, “In light of the evolving regulatory landscape and the rapid pace of enrollment in INSPIRE DUCHENNE, we have made the proactive decision to move our planned meeting with the FDA to the first half of 2026. The additional time will enable us to 1) generate a more fulsome data set for discussion with the FDA, 2) work towards a comprehensive external comparator based on high-quality, well-matched natural history data, 3) begin our process performance qualification (PPQ) manufacturing runs with our CDMO partner in preparation for a potential biologics license application (BLA) submission, and 4) initiate dosing in IMPACT DUCHENNE, our Phase 3 randomized, double-blind, placebo-controlled clinical trial that will be conducted outside of the United States. We believe these activities put Solid in the best position to deliver the most compelling package to regulators. “Our priority now is to rapidly build a robust data set to support a potential accelerated regulatory pathway for SGT-003, and we are committed to executing with urgency to deliver on SGT-003’s potential as quickly as possible. Beyond SGT-003, our lead pipeline programs continue to progress. We are excited to announce that we have recently activated the first clinical trial site for FALCON, a first-in-human Phase 1b clinical trial evaluating our novel dual route Friedreich’s ataxia gene therapy candidate, SGT-212. Later in the fourth quarter of 2025, we also expect to activate our first clinical trial site for ARTEMIS, a first-in-human Phase 1b clinical trial evaluating SGT-501, our gene therapy candidate intended to treat catecholaminergic polymorphic ventricular tachycardia. We look forward to continued advancement across our suite of therapeutics and delivery technologies in the quarters to come,” Mr. Cumbo concluded. INSPIRE DUCHENNE – Interim Clinical Data Update INSPIRE DUCHENNE is a Phase 1/2 first-in-human, open-label, single-dose, multicenter trial designed to evaluate the safety, tolerability and efficacy of SGT-003 in pediatric participants with Duchenne at a dose level of 1E14vg/kg. SGT-003 is administered as a one-time intravenous infusion. The interim clinical data reported in this release are as of a September 29, 2025, data cutoff date, with additional safety data reported as of October 31, 2025. As of October 31, 2025, 23 participants have been dosed in the trial. Enrollment in INSPIRE DUCHENNE is ongoing at 15 clinical trial sites across the United States, Canada, Italy and the United Kingdom. The Company expects to dose a total of 30 participants by early 2026. Statistical correlations, as measured by the Pearson correlation coefficient, were observed between Day 90 SGT-003 microdystrophin therapy and reconstitution of key components of the dystrophin-associated protein complex (DAPC), including beta-sarcoglycan and neuronal nitric oxide synthase (nNOS). Beta-sarcoglycan is a critical component of the dystrophin associated / sarcoglycan complex that is highly expressed in cardiac and skeletal muscle and plays a crucial role in maintaining muscle integrity. Myopathy and cardiomyopathy are observed in diseases in which the sarcoglycan complex is absent. nNOS plays an important role in protecting cardiac and skeletal muscle by improving vasodilation and reducing functional ischemia and muscle breakdown. Solid’s microdystrophin construct is the only microdystrophin gene therapy, approved or investigational, that contains the R16/R17 binding domain, which localizes nNOS to the muscle membrane. Strong correlations were also observed between SGT-003 microdystrophin therapy and improvements in several biomarkers of muscle integrity, including serum creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and embryonic myosin heavy chain (eMHC), suggesting a coordinated downstream effect of treatment with SGT-003. SGT-003, utilizing the Company’s proprietary, rationally designed capsid, AAV-SLB101, has demonstrated strong transduction, achieving a mean of 13 vector copies per nucleus (N=10) at Day 90, along with meaningful restoration of biologic correlates across several measures of microdystrophin, components of the DAPC, and multiple biomarkers of muscle integrity and preservation. In the 10 participants (aged 5-10) whose Day 90 biopsies were evaluated as of the September 29, 2025, data cutoff date, the Company observed mean microdystrophin expression of 58%, as measured by both western blot and mass spectrometry, and mean microdystrophin positive fibers of 51%, as measured by immunofluorescence. Furthermore, in each of those 10 participants, the Company observed properly localized and restored beta-sarcoglycan positive fibers at the mean 50% level as measured by immunofluorescence and nNOS activity-positive fibers (a less sensitive activity assay) at the mean 26% level. Available Day 360 biopsy data from 2 participants (aged 5) as of September 29, 2025, demonstrated encouraging and durable transduction, achieving a mean of 12 vector copies per nucleus, as well as robust mean microdystrophin expression of 107%, as measured by western blot, and 100%, as measured by mass spectrometry, mean microdystrophin positive fibers of 67% and mean beta-sarcoglycan positive fibers of 70%, both measured by immunofluorescence, and mean nNOS activity-positive fibers of 36%. Additionally, a mean 49% reduction in percent eMHC positive fibers, a histologic marker of muscle regeneration and disease progression, was observed at Day 90 (N=10). As muscle fibers deteriorate, muscle stem cells are activated to repair and replace damaged muscle fibers; during this process, new muscle fibers transiently express eMHC. In Duchenne, this stem cell-mediated repair process is futile because muscle fibers that are developed from stem cells lack dystrophin and therefore will be dystrophic. Consequently, the presence of eMHC positive fibers is an informative biomarker of disease progression, signaling constant muscle injury, breakdown and deterioration. A treatment-mediated decrease in eMHC is a favorable observation, and in combination with other markers of reduced muscle injury, suggests overall muscle preservation. Favorable reductions across a range of biomarkers of muscle injury and breakdown were observed through both Day 90 and Day 360: INSPIRE DUCHENNE – Interim Cardiac Monitoring Cardiomyopathy is a leading cause of death in Duchenne, with 25% of individuals displaying evidence of cardiomyopathy by six years of age, increasing to 59% by 10 years of age.1 Mean cardiac function trended into normal LVEF ranges (60-69%)2 for all SGT-003-treated participants who reached the Day 180 follow-up timepoint (N=8) as of the September 29, 2025, data cutoff date. Though cardiac injury biomarkers and cardiac imaging were collected primarily for safety analysis, early data may indicate a potential for benefit through reduction in troponin I (cTnI) and increased systolic function as measured by LVEF by echocardiography. Observed increases in systolic function as measured by LVEF appeared to have been driven largely by participants with low to low-normal systolic function at baseline. Mean reductions from baseline in serum cTnI of 31% at Day 90 (N=14) and 70% at Day 360 (N=3) were observed with reductions driven by participants who entered the trial with elevated baseline cTnI levels. cTnI is an important marker that can be predictive of severe cardiac disease in neuromuscular diagnoses. INSPIRE DUCHENNE – Interim Safety Update SGT-003 has been generally well tolerated in the 23 participants dosed as of October 31, 2025. Steroids alone were utilized as the prophylactic immunomodulation regimen. Signals of asymptomatic and self-resolving platelet declines and thrombocytopenia observed in early participants in the trial have been ameliorated in subsequent participants. As of October 31, 2025, there was one treatment-related serious adverse event (SAE) reported in the INSPIRE DUCHENNE trial. This SAE was identified as a Grade 3 immune-mediated myositis which, importantly, was not associated with muscle pain or weakness, and occurred in a participant who had a large deletion in a region coded for by SGT-003’s microdystrophin. The participant promptly responded to steroid treatment with all clinical symptoms noted at presentation resolving and with muscle biomarkers, including CK, declining well below baseline levels. This SAE was reviewed by the trial data and safety monitoring board (DSMB) with the recommendation to continue dosing without interruption. In Duchenne muscular dystrophy, transaminase elevations are the result of ongoing muscle injury as opposed to liver injury. Therapeutic interventions that lead to reductions in transaminases therefore indicate muscle protection in the setting of an avoidance of demonstrable liver injury, especially when more specific liver injury markers remain stable. As of the September 29, 2025, data cutoff date, we observed a mean alanine transaminase (ALT) reduction of 41% (N=14), a mean aspartate transaminase (AST) reduction of 25% (N=14) and stable mean gamma-glutamyl transferase (GGT) levels through Day 90 (N=14). Mean reductions of 40% AST and 29% ALT were observed in the three participants who reached the Day 360 follow-up. There have been no cases of drug-induced liver injury (DILI) observed as of October 31, 2025 (N=23). A presentation summarizing the interim data update can be accessed on the Presentations page of the Investors section of the Company’s website. SGT-003 Regulatory Update Solid plans to meet with the FDA in the first half of 2026 to discuss potential registrational pathways, including accelerated approval pathways, for SGT-003. Solid continues to dose participants in the INSPIRE DUCHENNE trial in the interim, with additional participant safety, clinical activity and functional data expected to enable a more robust discussion with the FDA. Critically, Solid has aligned with the FDA on SGT-003’s potency assay strategy and will continue additional commercial-readiness CMC activities, with PPQ manufacturing batches expected to be completed in 2026. In October 2025, Solid activated the first clinical trial site and began participant screening for IMPACT DUCHENNE, a Phase 3 randomized, double-blind, placebo-controlled clinical trial assessing SGT-003. IMPACT DUCHENNE will be conducted in pediatric participants outside of the United States (U.S.) and was designed to support potential ex-U.S. regulatory authorizations. We have received regulatory approvals to conduct IMPACT DUCHENNE in both Canada and Australia, and we plan to expand the trial into additional countries, subject to receipt of regulatory approvals. SGT-212 for Friedreich’s Ataxia (FA) In October 2025, the Company activated the first clinical trial site and began participant screening for FALCON, a first-in-human, open-label, Phase 1b clinical trial of SGT-212. The trial is expected to enroll non-ambulatory and ambulatory adult participants living with FA in up to three cohorts and is designed to evaluate the safety and tolerability of systemic and bilateral intradentate nucleus (IDN) administration of SGT-212. SGT-212 is the first investigational gene therapy for FA to utilize a dual route of administration and is intended to promote restoration of therapeutic levels of the frataxin protein to address the neurologic, cardiac and systemic clinical manifestations of FA. SGT-501 for Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) In the fourth quarter of 2025, Solid expects to activate the first clinical trial site for ARTEMIS, a first-in-human, open-label, Phase 1b clinical trial of SGT-501. The trial is expected to enroll adult participants with CPVT and is designed to evaluate the safety, tolerability and efficacy of SGT-501. SGT-501 is a novel gene therapy candidate intended to promote excess levels of the cardiac CASQ2 protein to address the underlying ryanodine receptor (RYR2) instability and calcium dysregulation seen in CPVT. There are currently no approved treatments that address the underlying mechanisms of CPVT. Platform Technologies – Capsids AAV-SLB101, the Company’s proprietary, next-generation capsid used in SGT-003, has been generally well tolerated in the 23 participants dosed in the INSPIRE DUCHENNE trial as of October 31, 2025, and has shown compelling levels of vector transduction, protein expression, and reduced liver targeting. Solid has executed over 30 agreements, including licenses, with corporations, institutions and academic labs for the use of AAV-SLB101, with additional agreements and licenses expected to be executed by year end. Additionally, the Company is building multiple cardiac and neuromuscular next-generation capsid and promoter libraries with final capsid selection from the first cardiac capsid library anticipated in the first half of 2026. Third Quarter 2025 Financial Highlights Cash Position: Solid had $236.1 million in cash, cash equivalents, and available-for-sale securities as of September 30, 2025, compared to $148.9 million as of December 31, 2024. The Company expects that its cash, cash equivalents, and available-for-sale securities as of September 30, 2025, will enable it to fund its operational runway into the first half of 2027. Research and Development (R&D) Expenses: R&D expenses for the third quarter of 2025 were $38.9 million, compared to $27.3 million for the third quarter of 2024. The increase of $11.5 million in research and development expenses was primarily due to a $12.8 million increase in costs for SGT-003 primarily related to manufacturing, regulatory, and clinical costs, a $2.7 million increase in personnel related expenses, a $0.9 million increase in costs for SGT-601 primarily related to manufacturing costs and research costs, partially offset by a $3.3 million decrease in costs for SGT-212 primarily related to lower license and milestone related costs partially offset by an increase in clinical costs, and a $1.8 million decrease in costs for SGT-501 primarily related to lower research and manufacturing costs. General and Administrative (G&A) Expenses: G&A expenses for the third quarter of 2025 were $9.2 million, compared to $7.9 million for the third quarter of 2024. The increase of $1.3 million was primarily related to a $0.9 million increase in personnel-related costs and a $0.4 million increase in legal and consulting fees. Net Loss: Net loss for the third quarter of 2025 was $45.8 million, compared to $32.7 million for the third quarter of 2024. References: 1. Gandhi S, et al. Cells. 2024;13(14):1168. 2. Romanowicz J, et al. J Am Soc Echocardiogr. 2023;36(3):310-323. About Duchenne Duchenne is a genetic muscle-wasting disease predominantly affecting boys, with symptoms usually appearing between three and five years of age. Duchenne is a progressive, irreversible, and ultimately fatal disease that affects approximately one in every 3,500 to 5,000 live male births and has an estimated prevalence of 5,000 to 15,000 cases in the United States alone. About SGT-003 SGT-003 is an investigational gene therapy containing a differentiated microdystrophin construct and a proprietary, next-generation capsid, AAV-SLB101, which was rationally designed to target integrin receptors, and has shown enhanced cardiac and skeletal muscle transduction with decreased liver targeting in nonclinical studies. SGT-003’s microdystrophin construct uniquely includes the R16/17 binding domain, which localizes nNOS to the muscle membrane. Nonclinical studies have shown that nNOS can improve blood flow to the muscle thereby reducing muscle breakdown from ischemia and muscle fatigue. Together, these design features suggest that SGT-003 could be a potential best-in-class investigational gene therapy for the treatment of Duchenne. About INSPIRE DUCHENNE INSPIRE DUCHENNE is a first-in-human, open-label, single-dose, multicenter Phase 1/2 clinical trial to evaluate the safety, tolerability and efficacy of SGT-003 in pediatric participants with a genetically confirmed Duchenne diagnosis with a documented dystrophin gene mutation. INSPIRE DUCHENNE is a multinational trial designed to enroll participants in the United States, Canada, the United Kingdom and Italy. About IMPACT DUCHENNE IMPACT DUCHENNE is a Phase 3 randomized, double-blind, placebo-controlled trial to evaluate the efficacy of a single dose of SGT-003 in pediatric participants with a genetically confirmed Duchenne diagnosis with a documented dystrophin gene mutation. IMPACT DUCHENNE is a multinational trial designed to enroll participants outside of the United States with the aim of supporting potential ex-U.S. regulatory authorizations. About Solid Biosciences Solid Biosciences is a precision genetic medicine company focused on advancing a portfolio of gene therapy candidates targeting rare neuromuscular and cardiac diseases, including SGT-003 for Duchenne muscular dystrophy (Duchenne), SGT-212 for Friedreich’s ataxia (FA), SGT-501 for catecholaminergic polymorphic ventricular tachycardia (CPVT), SGT-601 for TNNT2-mediated dilated cardiomyopathy and additional fatal, genetic cardiac diseases. The Company is also focused on developing innovative libraries of genetic regulators and other enabling technologies with promising potential to significantly impact gene therapy delivery cross-industry. Solid is advancing its diverse pipeline and delivery platform in the pursuit of uniting experts in science, technology, disease management, and care. Patient-focused and founded by those directly impacted by Duchenne, Solid’s mission is to improve the daily lives of patients living with devastating rare diseases. For more information, please visit www.solidbio.com. Cautionary Note Regarding Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding future expectations, plans and prospects for the company; the ability to successfully achieve and execute on the company’s goals, priorities and key clinical and preclinical milestones; strategies and expectations for the company’s SGT-003, SGT-212, SGT-501 and SGT-601 programs; expectations for additional site activations, planned enrollment, planned regulatory interactions and the potential approval pathways for SGT-003; plans for enrollment in the clinical trial of SGT-212; timing of planned clinical trial of SGT-501; the cash runway of the company and the sufficiency of the Company’s cash, cash equivalents, and available-for-sale securities to fund its operations; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “working” and similar expressions. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the company’s ability to advance SGT-003, SGT-212, SGT-501, SGT-601 and other preclinical programs, capsid libraries and other enabling technologies on the timelines expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; replicate in clinical trials positive results found in preclinical studies and early-stage clinical trials of the company’s product candidates; obtain, maintain or protect intellectual property rights related to its product candidates; replicate preliminary or interim data from clinicals trials in the final data of such trials; compete successfully with other companies that are seeking to develop Duchenne, FA, CPVT and other neuromuscular and cardiac treatments and gene therapies; manage expenses; and raise the substantial additional capital needed, on the timeline necessary, to continue development of SGT-003, SGT-212, SGT-501, SGT-601 and other candidates, achieve its other business objectives and continue as a going concern. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in the company’s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the company’s views as of the date hereof and should not be relied upon as representing the company’s views as of any date subsequent to the date hereof. The company anticipates that subsequent events and developments will cause the company's views to change. However, while the company may elect to update these forward-looking statements at some point in the future, the company specifically disclaims any obligation to do so. Solid Biosciences Investor Contact: Nicole Anderson Director, Investor Relations and Corporate Communications Solid Biosciences Inc. [email protected] Media Contact: Glenn Silver FINN Partners [email protected] Photos accompanying this announcement are available at https://www.globenewswire.com/NewsRoom/AttachmentNg/94c6aa47-2b3e-44d4-a9ec-a39f1d384aa3 https://www.globenewswire.com/NewsRoom/AttachmentNg/6b4661b4-2096-4207-a367-91c11b64f4aa This press release was published by a CLEAR® Verified individual.

- Duchenne (SGT-003): 15 participants dosed in the Phase 1/2 INSPIRE DUCHENNE trial and dosing remains ongoing; On track to discuss regulatory pathways with U.S. FDA in Q4 2025 - - FA (SGT-212): Phase 1b trial initiation expected in Q4 2025 - - CPVT (SGT-501): Phase 1b trial initiation expected in Q4 2025 - - Capsids (AAV-SLB101): Over 25 agreements or licenses with academic labs, institutions and corporations for the use of AAV-SLB101 have been executed - - Cash: Company ended Q2 2025 with $268.1 million in cash, cash equivalents and available-for-sale securities; Solid has anticipated cash runway into H1 2027 - CHARLESTOWN, Mass., Aug. 12, 2025 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. (Nasdaq: SLDB) (the “Company” or “Solid”), a life sciences company developing precision, next generation, genetic medicines for neuromuscular and cardiac diseases, today reported financial results for the second quarter ended June 30, 2025, and provided a business update. Bo Cumbo, President and CEO of Solid, commented: “With three clinical-stage programs for neuromuscular and cardiac diseases, Solid now stands at the forefront of innovation in genetic medicine. The strategic expansion of our pipeline beyond Duchenne to include differentiated therapies for both FA and CPVT marks a meaningful stride forward that reflects both our disciplined execution and steadfast dedication to the patient communities we serve. “We continue to receive overwhelming interest in the INSPIRE DUCHENNE trial from families and the clinical community and now have 10 active clinical sites and more than 20 additional participants identified to potentially enter the INSPIRE DUCHENNE trial. As of August 12, 2025, we have dosed 15 participants and SGT-003 continues to be well tolerated, with no treatment emergent SAEs observed, and we continue to recruit and dose patients. We look forward to FDA discussions later this year and will continue to work diligently to advance a new gene therapy option for the Duchenne community,” Mr. Cumbo concluded. Company Updates Neuromuscular Pipeline SGT-003 for Duchenne Muscular Dystrophy (Duchenne) As of August 12, 2025, 15 participants have been dosed in the INSPIRE DUCHENNE trial with participant dosing ongoing across multiple cohorts; SGT-003 continues to be well tolerated with no treatment emergent SAEs observed and an immune suppression regimen that consists of steroids alone. As of August 12, 2025, we have observed only one (N=1/15), Grade 1, Adverse Event of Special Interest (AESI) of elevated liver enzymes post treatment that occurred during the steroid taper period; this patient has shown no clinical manifestations. The Company expects to dose a minimum of 20 participants by year-end. In addition to the 15 participants dosed as of August 12, 2025, more than 20 additional patients have been screened, pre-screened or identified by clinical trial sites as potential participants in the INSPIRE DUCHENNE trial. The INSPIRE DUCHENNE trial now has 10 active sites across the U.S., Canada, Italy and the United Kingdom, with additional sites expected to be activated by year-end. The Company expects to initiate a separate randomized, double-blind, placebo-controlled trial evaluating SGT-003 outside of the United States in the fourth quarter of 2025, with the aim of supporting potential global regulatory authorizations. The Company expects to meet with the U.S. Food and Drug Administration (FDA) in the fourth quarter of this year to discuss regulatory pathways for SGT-003. SGT-212 for Friedreich’s Ataxia (FA) The Company expects to initiate a first-in-human, open-label, Phase 1b clinical trial of SGT-212 in the fourth quarter of 2025. The trial is expected to enroll non-ambulatory and ambulatory adult participants living with FA in up to three cohorts and is designed to evaluate the safety and tolerability of systemic and bilateral IDN administration of SGT-212. SGT-212 is the first investigational gene therapy for FA to utilize a dual route of administration and is intended to promote restoration of therapeutic levels of the frataxin protein to address the neurologic, cardiac and systemic clinical manifestations of FA. Cardiac Pipeline SGT-501 for Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) As announced on July 8, 2025, the U.S. FDA cleared the Investigational New Drug (IND) application and Health Canada approved the Clinical Trial Application (CTA) for SGT-501, a first-in-class, investigational gene therapy for the treatment of CPVT, a life-threatening, genetic arrhythmogenic disease with no approved therapies. As announced on July 23, 2025, SGT-501 received Fast Track designation from the FDA. SGT-501 previously received Orphan Drug and Rare Pediatric Disease designations from the FDA. SGT-501 is a novel gene therapy intended to promote excess levels of the cardiac CASQ2 protein to address the underlying ryanodine receptor (RYR2) instability and calcium dysregulation seen in CPVT. The Company expects to initiate a Phase 1b clinical trial in adult participants with CPVT to evaluate the safety, tolerability and efficacy of SGT-501 in the fourth quarter of 2025. SGT-601 for TNNT2 Thin Filament Cardiomyopathy SGT-601 is a novel gene therapy designed to treat cardiomyopathy caused by pathogenic variants in the TNNT2 gene, which codes for the cardiac troponin T protein. SGT-601 leverages AAV-SLB101 capsid delivery of the full-length, wild type TNNT2 transgene, with the aim of regulating cardiac muscle contraction and relaxation. IND-enabling preclinical work is underway, with proof-of-concept efficacy studies demonstrating that SGT-601 treatment elicited robust, cardiac-selective expression of TNNT2, resulting in improvements in survival, cardiac structure and function at multiple dose levels in a translationally relevant mouse model. There are no FDA-approved therapies that address the underlying cause of TNNT2-related cardiomyopathy. Platform Technologies – Capsids & Other Capsids & Promoters AAV-SLB101 is the Company’s proprietary capsid used in SGT-003, which has been well tolerated as of August 12, 2025 (N=15), in the Phase 1/2 INSPIRE DUCHENNE trial. In the first three participants dosed, for which 90-day biopsy biomarker data were initially reported in February 2025, rapid and robust levels of vector transduction, microdystrophin expression, and reduced liver targeting were observed. Solid currently has agreements and licenses with over 25 academic labs, institutions and corporations for the use of AAV-SLB101, with additional agreements and licenses expected to be executed over the coming quarters. The Company is building multiple cardiac and neuromuscular next-generation capsid and promoter libraries with final capsid selection from the first cardiac capsid library anticipated in the fourth quarter of 2025. Second Quarter 2025 Financial Highlights Cash Position: Solid had $268.1 million in cash, cash equivalents, and available-for-sale securities as of June 30, 2025, compared to $148.9 million as of December 31, 2024. The Company expects that its cash, cash equivalents, and available-for-sale securities as of June 30, 2025, will enable it to fund its operational runway into the first half of 2027. Research and Development (R&D) Expenses: R&D expenses for the second quarter of 2025 were $32.4 million, compared to $19.5 million for the second quarter of 2024. The increase of $13.0 million in research and development expenses was primarily due to a $9.9 million increase in costs for SGT-003 primarily related to manufacturing, regulatory, and clinical costs, a $2.3 million increase in personnel related expenses, a $2.1 million increase in costs for SGT-601 primarily related to manufacturing costs, a $1.0 million increase in costs for SGT-212 primarily related to clinical and research costs, partially offset by a $1.5 million decrease in costs for other development programs primarily related to lower research costs, and a $1.2 million decrease in costs for SGT-501 primarily related to lower research and manufacturing costs. General and Administrative (G&A) Expenses: G&A expenses for the second quarter of 2025 were $9.3 million, compared to $8.3 million for the second quarter of 2024. The increase of $1.0 million was primarily related to a $1.2 million increase in personnel related costs, partially offset by a $0.3 million decrease in consulting fees. Net Loss: Net loss for the second quarter of 2025 was $39.5 million, compared to $25.1 million for the second quarter of 2024. About Solid Biosciences Solid Biosciences is a precision genetic medicine company focused on advancing a portfolio of gene therapy candidates targeting rare neuromuscular and cardiac diseases, including Duchenne muscular dystrophy (Duchenne), Friedreich’s ataxia (FA), catecholaminergic polymorphic ventricular tachycardia (CPVT), TNNT2-mediated dilated cardiomyopathy, BAG3-mediated dilated cardiomyopathy, and additional fatal, genetic cardiac diseases. The Company is also focused on developing innovative libraries of genetic regulators and other enabling technologies with promising potential to significantly impact gene therapy delivery cross-industry. Solid is advancing its diverse pipeline and delivery platform in the pursuit of uniting experts in science, technology, disease management, and care. Patient-focused and founded by those directly impacted by Duchenne, Solid’s mission is to improve the daily lives of patients living with devastating rare diseases. For more information, please visit www.solidbio.com. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding future expectations, plans and prospects for the company; the ability to successfully achieve and execute on the company’s goals, priorities and key clinical and preclinical milestones; strategies and expectations for the company’s SGT-003, SGT-212, SGT-501 and SGT-601 programs; expectations for additional CTA filings, site activations, planned enrollment, planned regulatory interactions and the potential approval pathways for SGT-003; timing of planned clinical trials of SGT-212 and SGT-501; the cash runway of the company and the sufficiency of the Company’s cash, cash equivalents, and available-for-sale securities to fund its operations; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “working” and similar expressions. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the company’s ability to advance SGT-003, SGT-212, SGT-501, SGT-601 and other preclinical programs, capsid libraries and other enabling technologies on the timelines expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; replicate in clinical trials positive results found in preclinical studies and early-stage clinical trials of the company’s product candidates; obtain, maintain or protect intellectual property rights related to its product candidates; replicate preliminary or interim data from early-stage clinicals trials in the final data of such trials; compete successfully with other companies that are seeking to develop Duchenne, FA, CPVT and other neuromuscular and cardiac treatments and gene therapies; manage expenses; and raise the substantial additional capital needed, on the timeline necessary, to continue development of SGT-003, SGT-212, SGT-501, SGT-601 and other candidates, achieve its other business objectives and continue as a going concern. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in the company’s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the company’s views as of the date hereof and should not be relied upon as representing the company’s views as of any date subsequent to the date hereof. The company anticipates that subsequent events and developments will cause the company's views to change. However, while the company may elect to update these forward-looking statements at some point in the future, the company specifically disclaims any obligation to do so. Solid Biosciences Investor Contact: Nicole Anderson Director, Investor Relations and Corporate Communications Solid Biosciences Inc. [email protected] Media Contact: Glenn Silver FINN Partners [email protected]

- Duchenne (SGT-003): Participant dosing ongoing in the Phase 1/2 INSPIRE DUCHENNE trial; Solid on track to discuss accelerated pathways with U.S. FDA later in 2025 - - FA (SGT-212): Dosing of first participant anticipated in the second half of 2025 - - CPVT (SGT-501): FDA IND on track for submission first half of 2025 - - Cash: Company ended first quarter 2025 with $306.9 million in cash, cash equivalents, investments and available-for-sale securities; Solid has anticipated cash runway into the first half of 2027 - CHARLESTOWN, Mass., May 15, 2025 (GLOBE NEWSWIRE) -- Solid Biosciences Inc. (Nasdaq: SLDB) (the “Company” or “Solid”), a life sciences company developing precision, next generation, genetic medicines for neuromuscular and cardiac diseases, today reported financial results for the first quarter ended March 31, 2025, and provided a business update. Bo Cumbo, President and CEO of Solid, commented: “The positive initial three patient, 90-day data in the INSPIRE DUCHENNE trial of SGT-003, our next-generation, investigational gene therapy to treat Duchenne muscular dystrophy, were a milestone in the development of a meaningful treatment candidate for this terrible disease. With the initial data demonstrating robust microdystrophin expression and improvements across biomarkers of muscle integrity and, excitingly, encouraging biomarkers of cardiac and liver health, we continue to dose participants as we prepare to engage with the FDA later this year on the potential for accelerated pathways. “To our patient communities, we know that safety is a critical factor in choosing any medical therapy. SGT-003, utilizing our proprietary, rationally designed capsid, AAV-SLB101, contains the lowest dose of any Duchenne gene therapy currently marketed or in clinical development, and to date, has demonstrated an encouraging safety and tolerability profile. We look forward to the 28th Annual Meeting of the American Society of Gene and Cell Therapy (ASGCT) where, on Saturday, we will provide an interim safety update from the INSPIRE DUCHENNE trial during our late-breaking oral presentation. “As an organization, we are intensely focused on driving innovation and advancing the C&GT field with the aspiration to make gene therapies safer, more effective, and truly accessible. These efforts originate with our differentiated and thoughtfully designed neuromuscular and cardiac therapeutic pipeline and expand to the development and broad out-licensing of next-generation delivery technologies, beginning with AAV-SLB101. We look forward to executing across these objectives over the coming quarters to drive meaningful value for all of our stakeholders,” Mr. Cumbo concluded. Company Updates Neuromuscular Pipeline SGT-003 for Duchenne Muscular Dystrophy (Duchenne) As announced on February 18, 2025, the Company reported positive initial clinical data from the first three participants dosed in the Phase 1/2 INSPIRE DUCHENNE trial. SGT-003 has been well tolerated in all participants dosed to date, with no treatment emergent serious adverse events (SAEs) or AEs of acute liver injury observed. The INSPIRE DUCHENNE trial continues dosing participants across multiple cohorts, and the Company expects to dose approximately 20 total participants by year-end. The INSPIRE DUCHENNE trial now has eight active sites in the U.S., Canada and Italy, with additional sites expected to be activated by year-end. The Company plans to meet with the FDA later this year to share safety and efficacy results from additional treated participants in the INSPIRE DUCHENNE study and to discuss accelerated regulatory pathways. The Company expects the meeting to occur in the fourth quarter of 2025. SGT-212 for Friedreich’s Ataxia (FA) As announced on January 7, 2025, the FDA has cleared the IND for SGT-212 for the treatment of FA. SGT-212 is the first gene therapy candidate for FA to utilize a dual route of administration that was designed to promote restoration of therapeutic levels of the frataxin protein to address neurologic, cardiac and systemic clinical manifestations of FA. The Company expects to initiate a first-in-human, open-label, Phase 1b clinical trial of SGT-212 in the second half of 2025. The trial is expected to enroll non-ambulatory and ambulatory adult participants living with FA across up to three cohorts and is designed to evaluate the safety and tolerability of systemic and bilateral IDN administration of SGT-212. Cardiac Pipeline SGT-501 for Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) IND-enabling Good Laboratory Practice (GLP) toxicology studies of SGT-501 in non-human primates were completed in the first quarter of 2025. The Company anticipates submitting an IND for SGT-501 for the treatment of CPVT in 1H 2025. Platform Technologies – Capsids & Other Capsids & Promoters The Company is building multiple cardiac and neuromuscular next-generation capsid and promoter libraries with final capsid selection from the first cardiac capsid library anticipated in the fourth quarter of 2025. AAV-SLB101 is the Company’s proprietary capsid used in SGT-003, which in the initial three participants dosed in the INSPIRE DUCHENNE study demonstrated rapid and robust levels of vector transduction, microdystrophin expression, and reduced liver targeting. Solid currently has partnership agreements with 19 academic labs, institutions and corporations for the use of AAV-SLB101, with additional partnerships expected to be executed over the coming quarters. First Quarter 2025 Financial Highlights Cash Position: Solid had $306.9 million in cash, cash equivalents, and available-for-sale securities as of March 31, 2025, compared to $148.9 million as of December 31, 2024. The Company expects that its cash, cash equivalents, and available-for-sale securities as of March 31, 2025, will enable it to fund its operational runway into the first half of 2027. Research and Development (R&D) Expenses: R&D expenses for the first quarter of 2025 were $30.9 million, compared to $18.9 million for the first quarter of 2024. The increase of $12.0 million was primarily due to a $7.4 million increase in costs for SGT-003 primarily related to manufacturing, regulatory, and clinical costs, a $1.9 million increase in personnel-related expenses, a $1.3 million increase in other development program expenses primarily due to manufacturing costs, a $0.8 million increase in costs for SGT-212 primarily related to regulatory and clinical costs, and a $0.7 million increase in costs for SGT-501 primarily related to research, regulatory, and clinical costs. General and Administrative (G&A) Expenses: G&A expenses for the first quarter of 2025 were $9.1 million, compared to $8.0 million for the first quarter of 2024. The increase of $1.1 million was primarily due to a $1.7 million increase in personnel-related costs, partially offset by a $0.4 million decrease in other G&A expenses. Net Loss: Net loss for the first quarter of 2025 was $39.3 million, compared to $24.3 million for the first quarter of 2024. About Solid Biosciences Solid Biosciences is a precision genetic medicine company focused on advancing a portfolio of gene therapy candidates targeting rare neuromuscular and cardiac diseases, including Duchenne muscular dystrophy (Duchenne), Friedreich’s ataxia (FA), catecholaminergic polymorphic ventricular tachycardia (CPVT), TNNT2-mediated dilated cardiomyopathy, BAG3-mediated dilated cardiomyopathy, and additional fatal, genetic cardiac diseases. The Company is also focused on developing innovative libraries of genetic regulators and other enabling technologies with promising potential to significantly impact gene therapy delivery cross-industry. Solid is advancing its diverse pipeline and delivery platform in the pursuit of uniting experts in science, technology, disease management, and care. Patient-focused and founded by those directly impacted by Duchenne, Solid’s mission is to improve the daily lives of patients living with devastating rare diseases. For more information, please visit www.solidbio.com. Forward-Looking Statements This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding future expectations, plans and prospects for the company; the ability to successfully achieve and execute on the company’s goals, priorities and key clinical milestones; the company’s SGT-003 and SGT-212 programs, including expectations for additional CTA filings, site activations, planned enrollment, planned regulatory interactions and the potential accelerated approval pathway for SGT-003; the company’s expectations for submission of INDs; the cash runway of the company and the sufficiency of the Company’s cash, cash equivalents, and available-for-sale securities to fund its operations; and other statements containing the words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” “working” and similar expressions. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in, or implied by, such forward-looking statements. These risks and uncertainties include, but are not limited to, risks associated with the company’s ability to advance SGT-003, SGT-212, SGT-501, SGT-601 and other preclinical programs, capsid libraries and other enabling technologies on the timelines expected or at all; obtain and maintain necessary approvals from the FDA and other regulatory authorities; replicate in clinical trials positive results found in preclinical studies and early-stage clinical trials of the company’s product candidates; obtain, maintain or protect intellectual property rights related to its product candidates; replicate preliminary or interim data from early-stage clinicals trials in the final data of such trials; compete successfully with other companies that are seeking to develop Duchenne, FA, CPVT and other neuromuscular and cardiac treatments and gene therapies; manage expenses; and raise the substantial additional capital needed, on the timeline necessary, to continue development of SGT-003, SGT-212, SGT-501, SGT-601 and other candidates, achieve its other business objectives and continue as a going concern. For a discussion of other risks and uncertainties, and other important factors, any of which could cause the company’s actual results to differ from those contained in the forward-looking statements, see the “Risk Factors” section, as well as discussions of potential risks, uncertainties and other important factors, in the company’s most recent filings with the Securities and Exchange Commission. In addition, the forward-looking statements included in this press release represent the company’s views as of the date hereof and should not be relied upon as representing the company’s views as of any date subsequent to the date hereof. The company anticipates that subsequent events and developments will cause the company's views to change. However, while the company may elect to update these forward-looking statements at some point in the future, the company specifically disclaims any obligation to do so. Solid Biosciences Investor Contact: Nicole Anderson Director, Investor Relations and Corporate Communications Solid Biosciences Inc. [email protected] Media Contact: Glenn Silver FINN Partners [email protected] This press release was published by a CLEAR® Verified individual.