Solid Biosciences Inc.

Previous wording

Since inception, we have incurred significant net losses. Our net losses were $56.7 million and $39.3 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, we had an accumulated deficit of $1.0 billion. Prior to our acquisition of AavantiBio, Inc. in December 2022 (the “Acquisition”) we devoted substantially all of our efforts to research and development, including clinical development of SGT-001, which we are no longer developing, and preclinical development of SGT‑003, as well as to building out our management team and infrastructure. Following the Acquisition, we have devoted our efforts to the research and development of our other Candidates, including clinical development of SGT‑003, SGT‑212 and SGT-501, as well as building out our management team. We expect that it could be several years before we have a commercialized product, and we may never have a commercialized product. We expect to incur significant expenses and operating losses for the foreseeable future. We anticipate that our expenses will increase substantially if, and as, we:

Current wording

Since inception, we have incurred significant net losses. Our net losses were $111.5 million and $78.8 million for the six months ended June 30, 2026 and 2025, respectively. As of June 30, 2026, we had an accumulated deficit of $1.1 billion. Prior to our acquisition of AavantiBio, Inc. in December 2022 (the “Acquisition”) we devoted substantially all of our efforts to research and development, including clinical development of SGT-001, which we are no longer developing, and preclinical development of SGT‑003, as well as to building out our management team and infrastructure. Following the Acquisition, we have devoted our efforts to the research and development of our other Candidates, including clinical development of SGT‑003, SGT‑212 and SGT-501, as well as building out our management team. We expect that it could be several years before we have a commercialized product, and we may never have a commercialized product. We expect to incur significant expenses and operating losses for the foreseeable future. We anticipate that our expenses will increase substantially if, and as, we:

Previous wording

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the research and development of, conduct clinical trials of, and seek marketing approval for our Candidates. In addition, if we obtain marketing approval for our Candidates, we expect to incur significant expenses related to product sales, marketing, manufacturing and distribution. We also expect to continue to incur additional costs associated with operating as a public company. While we believe that our cash, cash equivalents and available-for-sale securities as of March 31, 2026 will be sufficient to fund our operating expenses and capital requirements into the first half of 2028, we have based this estimate on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently anticipate. In order to continue to operate our business beyond that time, we will need to raise additional funds. However, there can be no assurance that we will be able to generate funds on terms acceptable to us, on a timely basis, or at all. In addition, we anticipate that we will need additional funding to complete the development of our Candidates.

Current wording

We expect our expenses to increase in connection with our ongoing activities, particularly as we continue the research and development of, conduct clinical trials of, and seek marketing approval for our Candidates. In addition, if we obtain marketing approval for our Candidates, we expect to incur significant expenses related to product sales, marketing, manufacturing and distribution. We also expect to continue to incur additional costs associated with operating as a public company. While we believe that our cash, cash equivalents and available-for-sale securities as of June 30, 2026 will be sufficient to fund our operating expenses and capital requirements into mid-2028, we have based this estimate on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently anticipate. In order to continue to operate our business beyond that time, we will need to raise additional funds. However, there can be no assurance that we will be able to generate funds on terms acceptable to us, on a timely basis, or at all. In addition, we anticipate that we will need additional funding to complete the development of our Candidates.

Previous wording

In addition, our ability to conduct and complete our preclinical development testing and studies is contingent on our ability to source animals and other supplies required for the conduct of such testing and studies and the performance of animal models. If we are unable to obtain all necessary animals and other supplies required for the conduct of our preclinical testing and studies, or the animal models do not perform as expected, we may be unable to complete such preclinical development testing and studies in a timely manner or at all. For example, some of our IND-enabling toxicology and other studies require certain NHPs that may be imported from countries in which trade relation with the U.S. are or may become challenging or through vendors who may not be able to timely source certain NHPs or at all, which may impair our ability to complete preclinical development testing and studies to support IND or similar applications or delay submission of such applications. Additionally, we may fail to demonstrate adequate Candidate efficacy and/or safety as required by regulatory authorities. We may fail to access relevant, adequate, or necessary animal models, including genetic models of disease and non-human primates in particular, for use in such studies as requested by regulatory authorities. We may also experience substantial delays as a result of our reliance on contract research organizations (“CROs”) to conduct all animal model experimentation necessary to assess the efficacy and safety of our Candidates. Any of these factors may result in delays to Candidate progression, inability to obtain regulatory approval, and/or substantial increases in Candidate development costs.

Current wording

In addition, our ability to conduct and complete our preclinical development testing and studies is contingent on our ability to source animals and other supplies required for the conduct of such testing and studies and the performance of animal models. If we are unable to obtain all necessary animals and other supplies required for the conduct of our preclinical testing and studies, or the animal models do not perform as expected, we may be unable to complete such preclinical development testing and studies in a timely manner or at all. For example, some of our IND-enabling toxicology and other studies require certain non-human primates ("NHPs") that may be imported from countries in which trade relation with the U.S. are or may become challenging or through vendors who may not be able to timely source certain NHPs or at all, which may impair our ability to complete preclinical development testing and studies to support IND or similar applications or delay submission of such applications. Additionally, we may fail to demonstrate adequate Candidate efficacy and/or safety as required by regulatory authorities. We may fail to access relevant, adequate, or necessary animal models, including genetic models of disease and NHPs in particular, for use in such studies as requested by regulatory authorities. We may also experience substantial delays as a result of our reliance on contract research organizations (“CROs”) to conduct all animal model experimentation necessary to assess the efficacy and safety of our Candidates. Any of these factors may result in delays to Candidate progression, inability to obtain regulatory approval, and/or substantial increases in Candidate development costs.

Previous wording

During the conduct of clinical trials, participants may experience changes in their health, including illnesses, injuries, discomforts or a fatal outcome. Often, it is not possible to determine whether the Candidate being studied caused these conditions. For instance, we reported a serious adverse event in IGNITE DMD, which resulted in a clinical hold in November 2019, which has since been resolved. In April 2021, a participant treated with SGT-001 in IGNITE DMD experienced a systemic inflammatory response classified as a serious adverse event and considered by the investigator to be drug related. In addition, there has been one previously disclosed treatment-related serious adverse event in the INSPIRE DUCHENNE trial as of May 11, 2026, identified as a Grade 3 immune‑mediated myositis.

Current wording

During the conduct of clinical trials, participants may experience changes in their health, including illnesses, injuries, discomforts or a fatal outcome. Often, it is not possible to determine whether the Candidate being studied caused these conditions. For instance, we reported a serious adverse event in IGNITE DMD, which resulted in a clinical hold in November 2019, which has since been resolved. In April 2021, a participant treated with SGT-001 in IGNITE DMD experienced a systemic inflammatory response classified as a serious adverse event and considered by the investigator to be drug related. In addition, there have been two previously disclosed treatment-related serious adverse events in the INSPIRE DUCHENNE trial. Both events were reviewed by the data and safety monitoring board with the recommendation to continue dosing without interruption, and both events have resolved; however, we cannot guarantee that similar events will not happen in ongoing and future clinical trials of SGT-003.

Previous wording

There have been several significant adverse side effects in gene therapy treatments in the past, including reported cases of leukemia and death seen in other clinical trials. The FDA convened the Cellular, Tissue, and Gene Therapies Advisory Committee in September 2021 to discuss toxicity risks of AAV based gene therapy products and discussed risks including oncogenicity risks due to capsid genome integration, hepatotoxicity, thrombotic microangiopathy, and neurotoxicity (especially related to dorsal root ganglion toxicity). While new recombinant capsids have been developed with the intent to reduce these side effects, gene therapy is still a relatively new approach to disease treatment and additional adverse side effects could develop. There have been reports of significant adverse side effects, including muscle weakness, myocarditis, and acute liver injury, in clinical trials of other gene therapy treatments for Duchenne that may be related to the type and location of the specific gene mutation causing the disease. In another gene therapy treatment, there have been reports of AAV mediated acute liver failure leading to death in non-ambulatory boys with Duchenne in the setting of commercially available product. There also is the potential risk of delayed adverse events following exposure to gene therapy products due to persistent biologic activity of the genetic material or other components of products used to carry the genetic material. Possible adverse side effects that may occur with treatment with gene therapy products include an immunologic reaction early after administration that could substantially limit the effectiveness of the treatment or represent safety risks for patients. Additionally, in previous clinical trials involving AAV capsids for gene therapy, some subjects experienced the development of a positive ELISPOT test associated with T‑cell responses, which is of unclear clinical translatability. If T-cells are activated, the cellular immune response system may trigger the removal of transduced cells. If our gene transfer Candidates demonstrate a similar effect or other undesirable side effects, we may decide or be required to halt or delay further clinical development of our Candidates involving AAV capsids for gene therapy.

Current wording

2021 to discuss toxicity risks of AAV based gene therapy products and discussed risks including oncogenicity risks due to capsid genome integration, hepatotoxicity, thrombotic microangiopathy, and neurotoxicity (especially related to dorsal root ganglion toxicity). While new recombinant capsids have been developed with the intent to reduce these side effects, gene therapy is still a relatively new approach to disease treatment and additional adverse side effects could develop. There have been reports of significant adverse side effects, including muscle weakness, myocarditis, and acute liver injury, in clinical trials of other gene therapy treatments for Duchenne that may be related to the type and location of the specific gene mutation causing the disease. In another gene therapy treatment, there have been reports of AAV mediated acute liver failure leading to death in non-ambulatory boys with Duchenne in the setting of commercially available product. There also is the potential risk of delayed adverse events following exposure to gene therapy products due to persistent biologic activity of the genetic material or other components of products used to carry the genetic material. Possible adverse side effects that may occur with treatment with gene therapy products include an immunologic reaction early after administration that could substantially limit the effectiveness of the treatment or represent safety risks for patients. Additionally, in previous clinical trials involving AAV capsids for gene therapy, some subjects experienced the development of a positive ELISPOT test associated with T‑cell responses, which is of unclear clinical translatability. If T-cells are activated, the cellular immune response system may trigger the removal of transduced cells. If our gene transfer Candidates demonstrate a similar effect or other undesirable side effects, we may decide or be required to halt or delay further clinical development of our Candidates involving AAV capsids for gene therapy.

Previous wording

clinical trial sites or subjects dropping out of a trial;

Current wording

clinical trial sites or subjects dropping out of a trial or withdrawing from a trial, including withdrawals of consent that limit our ability to collect follow-up safety or efficacy data, which could compromise the completeness and integrity of our clinical data, delay development, or reduce the likelihood or timing of applicable regulatory approvals;

Previous wording

The EU Clinical Trials Regulation (“CTR”) which was adopted in April 2014 and repeals the EU Clinical Trials Directive, became applicable on January 31, 2022. The CTR aims to simplify and streamline the authorization, conduct and transparency of clinical trials in the European Union. We have only recently secured authorization to conduct clinical trials in the European Union pursuant to the

Current wording

The EU Clinical Trials Regulation (“CTR”) which was adopted in April 2014 and repeals the EU Clinical Trials Directive, became applicable on January 31, 2022. The CTR aims to simplify and streamline the authorization, conduct and transparency of clinical trials in the European Union. We have only recently secured authorization to conduct clinical trials in the European Union pursuant to the CTR and, accordingly, there is a risk that we may be delayed in commencing any such studies. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies governing clinical trials, our development plans may be impacted.

Previous wording

Even if we receive FDA approval of one or more of our Candidates in the United States, approval of a Candidate in the United States by the FDA does not ensure approval of such Candidate by regulatory authorities in other countries or jurisdictions, and approval by one foreign regulatory authority does not ensure approval by regulatory authorities in other foreign countries or by the FDA. Future sales of our Candidates outside of the United States will be subject to foreign regulatory requirements governing clinical trials, manufacturing and marketing approval. Approval procedures vary among jurisdictions and can involve requirements and administrative review periods different from, and more onerous than, those in the United States, including additional preclinical studies or clinical trials. In many countries outside the United States, a product candidate must be approved for reimbursement before it can be approved for sale in that country. If we submit a marketing authorization application (“MAA”) to the EMA for approval of

Current wording

Even if we receive FDA approval of one or more of our Candidates in the United States, approval of a Candidate in the United States by the FDA does not ensure approval of such Candidate by regulatory authorities in other countries or jurisdictions, and approval by one foreign regulatory authority does not ensure approval by regulatory authorities in other foreign countries or by the FDA. Future sales of our Candidates outside of the United States will be subject to foreign regulatory requirements governing clinical trials, manufacturing and marketing approval. Approval procedures vary among jurisdictions and can involve requirements and administrative review periods different from, and more onerous than, those in the United States, including additional preclinical studies or clinical trials. In many countries outside the United States, a product candidate must be approved for reimbursement before it can be approved for sale in that country. If we submit a marketing authorization application (“MAA”) to the EMA for approval of SGT-003, SGT-212, SGT-501 or other Candidates in the European Union, obtaining such approval from the European Commission following the opinion of the EMA is a lengthy and expensive process. Regulatory authorities in countries outside of the United States and the European Union also have requirements for approval of product candidates with which we must comply prior to marketing in those countries. Obtaining foreign regulatory approvals and compliance with foreign regulatory requirements could result in significant delays, difficulties and costs for us and could delay or prevent the introduction of our Candidates in certain countries.

Previous wording

Additionally, we could face heightened risks with respect to obtaining marketing authorization in the United Kingdom as a result of the withdrawal of the United Kingdom from the European Union, commonly referred to as Brexit. The United Kingdom is no longer part of the European Single Market and EU Customs Union. As of January 1, 2025, the MHRA is responsible for approving all medicinal products destined for the UK market (i.e., Great Britain and Northern Ireland), and the EMA will no longer have any role in approving medicinal products destined for Northern Ireland. On April 28, 2025, the United Kingdom Parliament adopted amendments to improve and strengthen the United Kingdom’s clinical trials regulatory regime, which are scheduled to take effect on April 28, 2026. Any delay in obtaining, or an inability to obtain, any marketing authorizations, as a result of Brexit or otherwise, may force us to restrict or delay efforts to seek regulatory approval in the United Kingdom for our Candidates, which could significantly and materially harm our business.

Current wording

Additionally, we could face heightened risks with respect to obtaining marketing authorization in the United Kingdom as a result of the withdrawal of the United Kingdom from the European Union, commonly referred to as Brexit. The United Kingdom is no longer part of the European Single Market and EU Customs Union. As of January 1, 2025, the MHRA is responsible for approving all medicinal products destined for the UK market (i.e., Great Britain and Northern Ireland), and the EMA will no longer have any role in approving medicinal products destined for Northern Ireland. On April 28, 2025, the United Kingdom Parliament adopted amendments to improve and strengthen the United Kingdom’s clinical trials regulatory regime, which took effect on April 28, 2026. Any delay in obtaining, or an inability to obtain, any marketing authorizations, as a result of Brexit or otherwise, may force us to restrict or delay efforts to seek regulatory approval in the United Kingdom for our Candidates, which could significantly and materially harm our business.

Previous wording

In addition, foreign regulatory authorities may change their approval policies and new regulations may be enacted. For instance, the EU pharmaceutical legislation is currently undergoing a complete review process, in the context of the Pharmaceutical Strategy for Europe initiative, launched by the European Commission in November 2020. The European Commission’s proposal for revision of several legislative instruments related to medicinal products (including potentially reducing the duration of regulatory data protection, revising the eligibility for expedited pathways, etc.) was published on April 26, 2023, with several amendments requested in April 2024. In December 2025, the European Parliament and European Council reached a provisional political agreement on the revision of EU pharmaceutical legislation, which is expected to be adopted by mid-2026. Key changes include updating regulatory data exclusivity to a new system with a regulatory data protection period of eight years and a reduced market exclusivity period of one year (which can be extended if specific conditions are fulfilled), adding launch/supply obligations, incentivizing antibiotic innovation with transferable vouchers, and streamlining approval procedures in the EU. If the legislation is finalized in line with the provisional political agreement, it will have a significant impact on the pharmaceutical industry.

Current wording

In addition, foreign regulatory authorities may change their approval policies and new regulations may be enacted. For instance, the EU pharmaceutical legislation is currently undergoing a complete review process, in the context of the Pharmaceutical Strategy for Europe initiative, launched by the European Commission in November 2020. The European Commission’s proposal for revision of several legislative instruments related to medicinal products (including potentially reducing the duration of regulatory data protection, revising the eligibility for expedited pathways, etc.) was published on April 26, 2023, with several amendments requested in April 2024. In December 2025, the European Parliament and European Council reached a provisional political agreement on the revision of EU pharmaceutical legislation, which is expected to be adopted by late-2026. Key changes include updating regulatory data exclusivity to a new system with a regulatory data protection period of eight years and a reduced market exclusivity period of one year (which can be extended if specific conditions are fulfilled), adding launch/supply obligations, incentivizing antibiotic innovation with transferable vouchers, and streamlining approval procedures in the EU. If the legislation is finalized in line with the provisional political agreement, it will have a significant impact on the pharmaceutical industry.

Previous wording

In 2025, the Trump Administration imposed a series of tariffs against U.S. trading partners pursuant to the International Emergency Economic Powers Act. On February 20, 2026, the U.S. Supreme Court ruled these tariffs unlawful. The Trump Administration immediately imposed new global tariffs pursuant to Section 122 of the Trade Act of 1974, which allows for tariffs of up to 15% for a period of up to 150 days.

Current wording

In 2025, the Trump Administration imposed a series of tariffs against U.S. trading partners pursuant to the International Emergency Economic Powers Act. On February 20, 2026, the U.S. Supreme Court ruled these tariffs unlawful. The Trump Administration immediately imposed new global tariffs pursuant to Section 122 of the Trade Act of 1974, which allows for tariffs of up to 15% for a period of up to 150 days. Pursuant to the statute, these tariffs expired on July 24, 2026. However, on July 23, 2026, the Office of the U.S. Trade Representative announced final action under Section 301 of the Trade Act of 1974 imposing new tariffs on imports from 60 trading partners based on findings that those countries had failed to adopt and effectively enforce prohibitions on imports of goods produced with forced labor. The new tariffs, set at either 10% or 12.5% depending on the country’s level of commitment to forced-labor import restrictions, took effect on July 24, 2026, and replaced the tariffs that had been imposed under Section 122.

Previous wording

Separately, in April 2025, the Department of Commerce announced an investigation under Section 232 of the Trade Expansion Act of 1962 into imports of pharmaceuticals and pharmaceutical ingredients, including finished products, medical countermeasures, critical inputs such as active pharmaceutical ingredients, and key starting materials, and derivative products of those items. On September 25, 2025, via a post on Truth Social, President Trump announced that, beginning October 1, 2025, all branded or patented drugs imported in the United States would face a 100% tariff. At the same time, President Trump indicated that these tariffs could be avoided by building pharmaceutical manufacturing facilities in the United States. Thereafter, President Trump delayed the October 1, 2025 effective date of the tariffs on branded or patented pharmaceutical products announcing that the Trump Administration had now “begun preparing” tariffs on manufacturers that do not build in the United States or enter into a most-favored-nation drug pricing agreement with the Trump Administration. A host of other U.S. tariff actions remain possible, including additional 25% tariffs on products from countries that do certain business with Iran or Cuba.

Current wording

Separately, in April 2025, the Department of Commerce announced an investigation under Section 232 of the Trade Expansion Act of 1962 into imports of pharmaceuticals and pharmaceutical ingredients, including finished products, medical countermeasures, critical inputs such as active pharmaceutical ingredients, and key starting materials, and derivative products of those items. U.S. trade policy remains subject to uncertainty and, accordingly, a host of other U.S. tariff actions remain possible.

Previous wording

Except as set forth below, we did not sell any securities during the three months ended March 31, 2026 that were not registered under the Securities Act of 1933, as amended (the "Securities Act"), and that have not otherwise been described in a Current Report on Form 8-K.

Current wording

We did not sell any securities during the three months ended June 30, 2026 that were not registered under the Securities Act of 1933, as amended, and that have not otherwise been described in a Current Report on Form 8-K.

Previous wording

(c) None of our directors or officers adopted orterminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K) during the first quarter of 2026.

Current wording

(c) None of our directors or officers adopted orterminated a Rule 10b5-1 trading arrangement or a non-Rule 10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K) during the second quarter of 2026.