Solid Biosciences Inc. Q3 FY2020 earnings call

• FDA lifted the clinical hold on the Phase I/II IGNITE DMD trial of SGT-001, with plans to resume dosing in Q1 2021.
• Entered into a strategic collaboration with Ultragenyx, which included a $40 million investment and potential for milestone and royalty-based value creation.
• Implemented manufacturing process changes reducing empty viral capsids from approximately 50% to 10%, averaging 90% full capsids.
• Amended the IGNITE DMD protocol to include prophylactic complement inhibitors (eculizumab and C1 esterase inhibitor), increased prednisone dose, and adjusted patient weight limits to reduce viral load.
• Continues to collect data from the six patients dosed in the IGNITE DMD trial and plans to share functional efficacy results (e.g., six-minute walk test, North Star Ambulatory Assessment) at an appropriate time.

No product segment financial performance reported as the company focuses on a single therapeutic area for Duchenne muscular dystrophy.

• Plan to resume dosing in the IGNITE DMD trial in the first quarter of 2021.
• Intend to actively dose patients in the IGNITE DMD trial throughout 2021 while prioritizing patient safety.
• Collaboration with Ultragenyx provides capital to advance SGT-001 development and potential for future value through milestones and royalties from programs under the collaboration.

• Uncertainty inherent in the clinical development and regulatory process for gene therapies.
• Impact of the COVID-19 pandemic on operations and clinical trials.
• Risks associated with complement activation and patient safety in clinical trials.

Q: Joseph Schwartz from SVB Leerink asked for details on manufacturing change improving product quality, scaling up the process, and timeline for IGNITE DMD trial disclosures.

A: Joel Schneider explained manufacturing change reduced empty capsids from ~50% to 10%, averaging 90% full capsids, and they are confident in scaling but will continue improving. Cathryn Clary mentioned resuming dosing in Q1, dosing patients one by one with DSMB review, and ongoing data collection from dosed patients.

Q: Joseph Schwartz followed up on microdystrophin quantification methods and exploration of other vectors post-Ultragenyx deal.

A: Joel Schneider said they use immunofluorescence, western blot, mass spec, and an in vitro expression assay for quantification. Ilan Ganot stated they are open to exploring other vectors and partnerships while retaining full rights to SGT-001.