Solid Biosciences Inc. (SLDB)

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

The following discussion and analysis of our financial condition and results of operations should be read in conjunction with our unaudited condensed consolidated financial statements and related notes appearing elsewhere in this quarterly report on Form 10-Q and our audited financial statements and related notes for the year ended December 31, 2025 included in our annual report on Form 10-K filed on March 19, 2026.

Some of the statements contained in this discussion and analysis or set forth elsewhere in this quarterly report on Form 10-Q, including information with respect to our plans and strategy for our business, constitute forward looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). We have based these forward-looking statements on our current expectations and projections about future events. The following information and any forward-looking statements should be considered in light of factors discussed elsewhere in this quarterly report on Form 10-Q particularly including those risks identified in Part II, Item 1A “Risk Factors” and our other filings with the Securities and Exchange Commission (the “SEC”).

Our actual results and timing of certain events may differ materially from the results discussed, projected, anticipated, or indicated in any forward-looking statements. We caution you that forward-looking statements are not guarantees of future performance and that our actual results of operations, financial condition and liquidity, and the development of the industry in which we operate may differ materially from the forward-looking statements contained in this quarterly report on Form 10-Q. Statements made herein are made as of the date of the filing of this Form 10-Q with the SEC and should not be relied upon as of any subsequent date. Even if our results of operations, financial condition and liquidity, and the development of the industry in which we operate are consistent with the forward‑looking statements contained in this quarterly report on Form 10-Q, they may not be predictive of results or developments in future periods. We disclaim any obligation, except as specifically required by law and the rules of the SEC, to publicly update or revise any such statements to reflect any change in our expectations or in events, conditions or circumstances on which any such statements may be based or that may affect the likelihood that actual results will differ from those set forth in the forward-looking statements.

We caution readers not to place undue reliance on any forward-looking statements made by us, which speak only as of the date they are made.

Overview

We are a life sciences company focused on advancing a portfolio of current and future gene therapy candidates, which we refer to collectively as our Candidates, including SGT-003 for the treatment of Duchenne muscular dystrophy (“Duchenne”), SGT-212 for the treatment of Friedreich’s ataxia (“FA”), SGT-501 for the treatment of catecholaminergic polymorphic ventricular tachycardia (“CPVT”), SGT-601 for the treatment of TNNT2-mediated dilated cardiomyopathy (“TNNT2 DCM”), and additional assets for the treatment of genetic cardiac and neuromuscular diseases, at different stages of development, with varying levels of investment. 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. We are advancing our diverse pipeline across rare neuromuscular and cardiac diseases, bringing together experts in science, technology, disease management and care. Patient-focused and founded by those directly impacted by Duchenne, our mission is to improve the daily lives of patients living with these devastating diseases.

Solid was purpose-built to advance the best science and accelerate the discovery and development of treatments that may benefit all patients with Duchenne. As we expand to bring meaningful treatments to patients living with other neuromuscular and cardiac diseases, the values and guiding principles that drive us continue. Our corporate vision is to build an innovation platform enabling the discovery and development of high-value genetic medicines for neuromuscular and cardiac diseases by integrating internal capabilities, including a vector core, use of validated animal models, optimized expression cassettes, novel platform technologies including capsids and regulatory expertise, and collaborations with leaders in related clinical and research fields. Our mission, which guides our operations, is to treat and change the course of neuromuscular and cardiac diseases at all stages. Underscoring this mission, our disease-focused business model is founded on the following fundamental principles:

•
identify and develop meaningful therapies for underserved patients with sometimes fatal neuromuscular and cardiac diseases;

•
build innovative libraries of delivery capsids and other enabling technologies with the potential to have broad impact on the gene therapy field at large;

•
bring together the leading experts in neuromuscular and cardiac diseases, science, technology, disease management and care; and

•
be guided by the needs of these patients.

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We are continuing to advance our pipeline of Candidates. The U.S. Food and Drug Administration (the “FDA”) has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations for SGT-003 for Duchenne, and SGT-003 has also been awarded Orphan Drug designation from the European Commission for the treatment of Duchenne, in addition to an Innovation Passport by the new UK Innovative Licensing and Access Pathway, which aims to accelerate time to market and facilitate patient access to new medicines in the United Kingdom. The FDA has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations to SGT-212 for the treatment of FA and SGT-501 for the treatment of CPVT.

As we continue to pursue opportunities in both the U.S. and international markets, we remain attentive to evolving global economic conditions, including uncertainties related to international trade policies, tariffs, and supply chain dynamics. Although these factors have not had a material impact on our operations to date, future changes in trade regulations, tariff structures, or logistical constraints could influence the cost, availability, or timing of materials and components used in our manufacturing processes. We continue to monitor these developments closely.

SGT-003

Participant dosing in the Phase 1/2 INSPIRE DUCHENNE trial of SGT-003 began in the second quarter of 2024. The INSPIRE DUCHENNE trial 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 patients with Duchenne at a dose of 1E14vg/kg. SGT-003 is administered as a one-time intravenous infusion. Since initiation of the INSPIRE DUCHENNE clinical trial, we amended the clinical trial protocol to increase the anticipated participant enrollment size, expand the participant cohort age groups and extend the time points of certain secondary objective measurements.

On March 11, 2026, we announced positive new interim data from the Phase 1/2 INSPIRE DUCHENNE clinical trial as of a February 23, 2026 data cutoff date. For a full description of the initial results from the INSPIRE DUCHENNE trial, see Part I, Item I, “Business” in our Annual Report on Form 10-K filed on March 19, 2026.

SGT-003 has been generally well tolerated in the 53 participants dosed in the Phase 1/2 INSPIRE DUCHENNE clinical trial as of August 4, 2026. One study participant withdrew consent after the Day 60 follow-up visit. No treatment-related adverse events were seen in this participant. 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. As of August 4, 2026, there were two previously disclosed treatment-related serious adverse events reported in the INSPIRE DUCHENNE trial.

The INSPIRE DUCHENNE trial is ongoing and being conducted at clinical sites across the United States, Canada, Italy and the United Kingdom. We believe we have aligned with the FDA on SGT-003's potency assay strategy and will continue commercial-readiness CMC activities, with our process performance qualification manufacturing batches to be completed in 2026.

In October 2025, we activated the first clinical trial site and began screening participants for IMPACT DUCHENNE, a Phase 3 randomized, double-blind, placebo-controlled trial evaluating SGT-003. In February 2026, we announced positive feedback from a Type C meeting with the FDA where we reached alignment on the IMPACT DUCHENNE trial design, including: the patient population of ambulant participants 7 to 12 years of age, the primary endpoint of change from baseline in Time to Rise (TTR) velocity from supine position evaluated at 18 months and other key secondary endpoints. Clinical trial sites for IMPACT DUCHENNE 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. Participant screening is underway and we dosed our first participant in the IMPACT DUCHENNE trial in April 2026.

We plan 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; we expect to provide an update as discussions progress.

The FDA has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations for SGT-003 and the European Commission has granted Orphan drug designation for SGT-003 for the treatment of Duchenne. SGT-003 has been awarded an Innovation Passport by the new UK Innovative Licensing and Access Pathway, which aims to accelerate time to market and facilitate patient access to new medicines in the United Kingdom.

Additionally, 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.

SGT-212

In January 2025, we announced that the FDA cleared our IND for SGT-212 for the treatment of FA. In October 2025, we activated the first clinical trial site and began screening participants for FALCON, an open-label, multi-center Phase 1b clinical trial of SGT-212, and in January 2026, we dosed the first participant in the trial. Two participants have been dosed in the FALCON clinical trial and SGT-212 has been well tolerated with no treatment related serious adverse events observed as of August 4, 2026.

The trial is expected to enroll approximately 10 non-ambulatory and ambulatory adult participants (aged 18-40) living with FA in up

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to three cohorts and is designed to evaluate the safety and tolerability of contemporaneous IDN and systemic IV infusion of SGT-212, with initial data anticipated in the first quarter of 2027, subject to participant enrollment. The FDA has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations to SGT-212 for the treatment of FA.

SGT-501

In July 2025, we announced that the FDA cleared our IND and that Health Canada approved our clinical trial application for SGT-501 for the treatment of CPVT. In January 2026, we announced that clinical trial sites have been activated and participant screening is underway in the ARTEMIS clinical trial, an open-label, multi-center Phase 1b clinical trial evaluating SGT-501 in adult participants with CPVT

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Overview

We are a life sciences company focused on advancing a portfolio of current and future gene therapy candidates, which we refer to collectively as our Candidates, including SGT-003 for the treatment of Duchenne muscular dystrophy (“Duchenne”), SGT-212 for the treatment of Friedreich’s ataxia (“FA”), SGT-501 for the treatment of catecholaminergic polymorphic ventricular tachycardia (“CPVT”), SGT-601 for the treatment of TNNT2-mediated dilated cardiomyopathy (“TNNT2 DCM”), and additional assets for the treatment of genetic cardiac and neuromuscular diseases, at different stages of development, with varying levels of investment. We are advancing our diverse pipeline across rare neuromuscular and cardiac diseases, bringing together experts in science, technology, disease management and care. Patient-focused and founded by those directly impacted by Duchenne, our mission is to improve the daily lives of patients living with these devastating diseases.

Solid was purpose-built to advance the best science and accelerate the discovery and development of treatments that may benefit all patients with Duchenne. As we expand to bring meaningful treatments to patients living with other neuromuscular and cardiac diseases, the values and guiding principles that drive us continue. Our corporate vision is to build an innovation platform enabling the discovery and development of high-value genetic medicines for neuromuscular and cardiac diseases by integrating internal capabilities, including a vector core, use of validated animal models, optimized expression cassettes, novel capsids and regulatory expertise, and collaborations with leaders in related clinical and research fields. Our mission, which guides our operations, is to treat and change the course of neuromuscular and cardiac diseases at all stages. Underscoring this mission, our disease-focused business model is founded on the following fundamental principles:

•
identify and develop meaningful therapies for underserved patients with sometimes fatal neuromuscular and cardiac diseases;

•
build innovative libraries of delivery capsids and other enabling technologies with the potential to have broad impact on the gene therapy field at large;

•
bring together the leading experts in neuromuscular and cardiac diseases, science, technology, disease management and care; and

•
be guided by the needs of these patients.

We are continuing to advance our pipeline of Candidates. The U.S. Food and Drug Administration (the “FDA”) has granted Fast Track, Orphan Drug, and Rare Pediatric Disease designations for SGT-003 for Duchenne and SGT-003 has also been awarded an Innovation Passport by the new UK Innovative Licensing and Access Pathway. The FDA has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations to SGT-212 for the treatment of FA and SGT-501 for the treatment of CPVT.

As we continue to pursue opportunities in both the U.S. and international markets, we remain attentive to evolving global economic conditions, including uncertainties related to international trade policies, tariffs, and supply chain dynamics. Although these factors have not had a material impact on our operations to date, future changes in trade regulations, tariff structures, or logistical constraints could influence the cost, availability, or timing of materials and components used in our manufacturing processes. We continue to monitor these developments closely.

SGT-003

Participant dosing in the Phase 1/2 INSPIRE DUCHENNE trial of SGT-003 began in the second quarter of 2024. The INSPIRE DUCHENNE trial 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 patients with Duchenne at a dose of 1E14vg/kg. SGT-003 is administered as a one-time intravenous infusion. Since initiation of the INSPIRE DUCHENNE clinical trial, we amended the clinical trial protocol to increase the anticipated participant enrollment size, expand the participant cohort age groups, and extend the time points of certain secondary objective measurements. In connection with the expanded clinical trial, we have initiated work for additional Good Manufacturing Practices (“GMP”) batches of SGT‑003.

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On March 11, 2026, we announced positive new interim data from the Phase 1/2 INSPIRE DUCHENNE clinical trial.

The interim clinical data reported is as of a February 23, 2026, data cutoff date. SGT-003 has been generally well tolerated in the 41 participants dosed as of March 18, 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. As of March 18, 2026, there has been one treatment-related serious adverse event reported in the INSPIRE DUCHENNE trial. This serious adverse event 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 trial participant promptly responded to steroid treatment and the event has resolved. This serious adverse event was reviewed by the data and safety monitoring board (DSMB) with the recommendation to continue dosing without interruption.

For a full description of the initial results from the INSPIRE DUCHENNE trial, see Part I, Item I, “Business” appearing in this Annual Report on Form 10-K.

Enrollment and dosing in the INSPIRE DUCHENNE trial is ongoing and being conducted at 15 clinical sites across the United States, Canada, Italy and the United Kingdom. We believe we have aligned with the FDA on SGT-003's potency assay strategy and will continue commercial-readiness CMC activities, with our process performance qualification manufacturing batches to be completed in 2026.

In October 2025, we activated the first clinical trial site and began screening participants for IMPACT DUCHENNE, a Phase 3 randomized, double-blind, placebo-controlled trial evaluating SGT-003. In February 2026, we announced positive feedback from a Type C meeting with the FDA where we reached alignment on the IMPACT DUCHENNE trial design, including: the patient population of ambulant participants 7 to 12 years of age, the primary endpoint of change from baseline in Time to Rise (TTR) velocity from supine position evaluated at 18 months and other key secondary endpoints. The IMPACT DUCHENNE trial is currently planned to be conducted at sites in Australia, Canada, the European Union and the United Kingdom, and due to strong key opinion leader and community demand, we are also evaluating the potential to open clinical trial sites in the United States. Participant screening is underway and we anticipate dosing the first participant in the Phase 3 IMPACT DUCHENNE trial in April 2026.

In the first half of 2026, we plan to have additional meetings with the FDA to receive guidance on a potential accelerated approval pathway for SGT-003 and we expect to provide regulatory and clinical updates in mid-2026.

The FDA has granted Fast Track, Orphan Drug, and Rare Pediatric Disease designations for SGT-003 for the treatment of Duchenne. SGT-003 has been awarded an Innovation Passport by the new UK Innovative Licensing and Access Pathway, which aims to accelerate time to market and facilitate patient access to new medicines in the United Kingdom.

SGT-212

In January 2025, we announced that the FDA cleared our IND for SGT-212 for the treatment of FA. In October 2025, we activated the first clinical trial site and began screening participants for FALCON, an open-label, multi-center Phase 1b clinical trial of SGT-212, and in January 2026, we dosed the first participant in the trial. As of March 18, 2026, there have been no serious adverse events and no treatment-related adverse events reported in the FALCON trial. Intra-procedural MRI imaging demonstrated promising IDN targeting and coverage. The trial is expected to enroll approximately 10 non-ambulatory and ambulatory adult participants (aged 18-40) living with FA in up to three cohorts and is designed to evaluate the safety and tolerability of contemporaneous IDN and systemic IV infusion of SGT-212 with initial data anticipated in the second half of 2026, subject to participant enrollment. The FDA has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations to SGT-212 for the treatment of FA.

SGT-501

In July 2025, we announced that the FDA cleared our IND and that Health Canada approved our clinical trial application for SGT-501 for the treatment of CPVT. In January 2026, we announced that clinical trial sites have been activated and participant screening is underway in the ARTEMIS clinical trial, an open-label, multi-center Phase 1b clinical trial evaluating SGT-501 in adult participants with CPVT. The ARTEMIS trial is designed to evaluate the safety and tolerability of a single IV infusion of SGT-501. We anticipate dosing our first participant in the second quarter of 2026 with initial safety data anticipated in the second half of 2026, subject to participant enrollment.

The FDA has granted Fast Track, Orphan Drug and Rare Pediatric Disease designations to SGT-501 for the treatment of CPVT.

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Other Cardiac Programs

We are currently developing a preclinical product candidate, SGT-601, for the treatment of TNNT2 DCM. Efficacy studies in mice suggest that SGT-601 treatment resulted in a restoration of ejection fraction function and a stabilization in cardiac function over time.

Capsids

In March of 2026, we began using the mark POLARIS-101TM to represent our AAV-SLB101 capsid (“POLARIS-101TM”). POLARIS-101TM is our rationally designed, proprietary capsid used in SGT-003 for Duchenne, which has been generally well tolerated as of March 18, 2026 (N=41) in the INSPIRE DUCHENNE clinical trial, and was also well tolerated in nonclinical NHP and mouse models. We aim to license POLARIS-101TM broadly to corporations, institutions and academic labs pursuing neuromuscular and cardiac rare disease research, with more than 50 agreements including licenses executed.

We are focused on developing transformative treatments to improve the lives of patients with rare neuromuscular and cardiac diseases. The majority of our current programs are designed to treat these diseases with gene transfer products. Gene transfer, a type of gene therapy, is designed to address diseases caused by mutated genes through the delivery of functional versions of genes, called transgenes. The transgenes are then utilized by the body to produce desired proteins that act therapeutically to treat the condition. In addition to a transgene, our gene transfer Candidates include a viral capsid or vector (a protein shell utilized as a vehicle to deliver a transgene to cells in the body) and a promoter (a specialized DNA sequence that directs cells to produce the protein in specific tissues). The capsid is modified to no longer self-replicate yet still retains its ability to introduce new genetic material directly into patients’ cells. Adeno-associated virus (“AAV”) capsids have been approved for use to deliver transgenes to patients, including via systemic delivery as well as stereotactic neurosurgical administration to the brain. The use of AAV capsids to deliver gene therapies has also been extensively studied by third parties in human clinical trials for multiple disease indications, and in certain of these trials AAV was delivered systemically to the participant.

We are building cardiac and neuromuscular next-generation capsid and promoter libraries with capsid selection from the first library anticipated in the second half of 2026.

Our Operations

Due to our significant research and development expenditure, licensing and patent investment, and general and administrative costs associated with our operations, we have generated subs

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