Taysha Gene Therapies, Inc. (NASDAQ:TSHA) has announced pivotal progress in its TSHA-102 gene therapy program for Rett syndrome, following written alignment with the FDA on a single-arm, open-label pivotal trial targeting patients aged six and older.
This population, shown by natural history data to have virtually zero chance of regaining developmental milestones, saw a 100% responder rate in the REVEAL Part A trial: all 10 treated patients gained or regained at least one developmental milestone post-TSHA-102, with high-dose recipients showing faster and deeper improvements. No serious adverse events or dose-limiting toxicities were reported.
A scientist holding a Petri dish filled with a gene therapy sample.
Taysha Gene Therapies, Inc.’s pivotal Part B trial, expected to launch in Q3 2025, will enroll 15 females in the developmental plateau stage, using each patient as their own control and video-based, blinded milestone assessment as the primary endpoint. The FDA’s support, based on robust longitudinal data from over 1,100 Rett patients, marks a major regulatory milestone.
TSHA-102, a one-time AAV9 gene therapy delivering functional MECP2, is designed to address the genetic root cause of Rett syndrome, a devastating disorder with no current disease-modifying treatments. Taysha Gene Therapies, Inc. will present further details at the IRSF Rett Syndrome Scientific Meeting in June.
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