Taysha halts gene therapy for rare nerve disease after FDA and Astellas feedback

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Astellas has declined the opportunity to exercise an option for an asset from Taysha Gene Therapies. Taysha, facing study design feasibility challenges after discussions with the FDA, has consequently halted internal development of the candidate and added it to a growing list of deprioritized programs. Taysha had granted Astellas an option to license its gene therapy candidate TSHA-120 for the treatment of giant axonal neuropathy (GAN) as part of a two-asset agreement, with Astellas paying $20 million upfront and investing $30 million in Taysha. The decision regarding the GAN program was contingent on the outcome of the end-of-phase 2 meeting with the FDA.

Following the meeting, the situation rapidly deteriorated. The FDA stressed the importance of addressing the variability in disease progression in GAN and expressed concerns about the primary endpoint. Taysha submitted a new analysis, but it failed to change the FDA’s perspective. After a second meeting, the FDA continued to recommend a randomized, double-blind, placebo-controlled trial as the preferred approach to demonstrate TSHA-120’s efficacy. The agency also suggested a single-arm trial with an external control group matched with treated patients, along with longer-term follow-up. However, none of these options were deemed favorable by Taysha due to study design feasibility challenges. Consequently, the biotech has ceased the development of TSHA-120 in GAN and is exploring external strategic options for the program.

“We believe we have made significant progress in demonstrating the therapeutic potential of TSHA-120 and identifying a potential 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 BLA submission in this ultra-rare neurodegenerative disease. I want to express our gratitude to the patients and families who participated in the trial, the GAN community, and the National Institutes of Health (NIH) for their partnership in establishing the foundation for a potential treatment option in GAN. We plan to pursue external strategic options for TSHA-120 that may enable further development of TSHA-120 and help patients with this devastating disease.”

– Sean P. Nolan, Chairman and Chief Executive Officer of Taysha

Taysha will need to identify a partner willing to address the challenges that led both Astellas and Taysha to abandon the asset if it seeks to find a collaborator for the program.

This decision marks another step in the downsizing of Taysha’s once-extensive pipeline. When the biotech went public in September 2020, it had listed 18 programs in its portfolio, many of which were in the discovery stage and targeted undisclosed indications. However, the company’s publicly disclosed pipeline now primarily consists of one priority candidate, TSHA-102 for Rett syndrome, and three deprioritized assets, including TSHA-120.

The discontinuation of TSHA-120 has extended Taysha’s cash runway into the fourth quarter of 2025 compared to the previous plan, positioning the company to generate data on TSHA-102 in Rett syndrome.

“This strategic program prioritization is expected to extend our cash runway into the fourth quarter of 2025 to support the continued clinical development of TSHA-102 in Rett syndrome, a rare neurodevelopmental disorder with no approved treatments that target the genetic root cause of the disease. We remain focused on continuing to evaluate the therapeutic potential of TSHA-102 in our ongoing REVEAL Phase 1/2 trial in adults and our planned pediatric trial.” 

– Sean P. Nolan, Chairman and Chief Executive Officer of Taysha

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