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Taysha Gene Therapies Halts Giant Axonal Neuropathy Drug Development on FDA Feedback

NEW YORK – Taysha Gene Therapies on Tuesday said it is discontinuing development of TSHA-120, its gene therapy candidate for giant axonal neuropathy (GAN), following feedback from the US Food and Drug Administration on the company's intended registrational path.

"Following FDA feedback, we have made the decision to discontinue further development of the program due to challenges related to the feasibility of the study designs to support a potential [biologics license application] submission in this ultra-rare neurodegenerative disease," said Taysha Chairman and CEO Sean Nolan in a statement.

Dallas-based Taysha last year submitted a subset of available evidence from a Phase I/II trial of TSHA-120 and reviewed the data with the FDA in a type B end-of-Phase II meeting. In that meeting the FDA provided feedback that the company would need to address patient heterogeneity in terms of disease progression in GAN, an extremely rare genetic neurodegenerative disorder, and concerns about using motor function measure 32 (MFM32) as an endpoint. Taysha subsequently submitted another analysis of data from a natural history and interventional trial comparing functional and biological measurements against a disease progression model.

However, in the latest type C meeting, the FDA continued to recommend a randomized, double-blind, placebo-controlled trial to demonstrate efficacy, the company said. The agency also suggested a potential path for a single-arm trial with an external control group and recommended longer-term follow-up.

However, Taysha said it has determined that discontinuing development of the gene therapy will reduce operating expenses and is expected to extend its cash runway into the end of 2025, which will support continued development of TSHA-102, its gene therapy being assessed in a Phase I/II trial for Rett syndrome.

Taysha on Tuesday also said that Astellas Gene Therapies, which last year invested $50 million into Taysha, has elected not to exercise its option to obtain an exclusive license to TSHA-120. Taysha will continue to pursue external strategic options for the TSHA-120 program, according to the company.