Insights:Letter to the Duchenne Community: IGNITE DMD Phase I/II Clinical Trial and 2022 Priorities

Dear Duchenne Community,

As we embark on a new year, we are pleased to share an update on IGNITE DMD, our ongoing Phase I/II clinical trial, as well as progress in expanding our pipeline of Duchenne treatments. Earlier this week we shared this announcement and provided a business update at the Annual JP Morgan Healthcare Conference this morning.

IGNITE DMD Phase I/II Clinical Trial for SGT-001

We continue to work with urgency and scientific rigor to advance SGT-001. We are pleased to share that we successfully dosed the ninth patient in the IGNITE DMD study in November 2021 utilizing our updated risk mitigation strategy and second-generation manufacturing process. We plan to continue dosing in 2022, employing these strategies to enhance patient safety. We look forward to sharing additional expression via immunofluorescence and Western blot, functional, pulmonary and patient reported outcomes data from the clinical trial in the first half of this year.

SGT-003

We also shared pre-clinical data on SGT-003, next-generation Duchenne microdystrophin gene transfer program that utilizes a rationally designed AAV-based vector to deliver the same proprietary and differentiated nNOS containing microdystrophin construct that is incorporated into SGT-001.

The additional data on SGT-003 demonstrates increased protein expression and more targeted biodistribution compared to AAV9 in DMD mdx mice. The data reflected multiple-fold increases in skeletal and cardiac muscle biodistribution with decreased levels in the liver to ultimately improve safety.

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We expect to initiate IND-enabling studies and work closely with our manufacturing partner in 2022 to support an IND submission in early 2023.

Platform Technologies

Additionally, we are pleased to announce encouraging data from two Platform Technologies, Novel Capsids and Dual Gene Expression (DGE). These programs are part of the company’s ongoing research efforts to develop innovative technologies that Solid believes may hold potential to translate into meaningful treatments and drive the company’s future pipeline expansion.

We are truly grateful for the community’s continued support and remain dedicated to improving the lives of all those living with Duchenne. We look forward to sharing future updates.

Best regards,

Solid Biosciences Team

Upcoming Conferences and Presentations:

Parent Project Italy, February 17-20, 2022

Muscular Dystrophy Association Clinical and Scientific Conference, March 13-16, 2022