Taysha Gene Therapies Announces Pivotal Part B Trial Design Details for TSHA-102 in Rett Syndrome Enabled by IRSF Natural History Data and Positive Clinical Data from Part A of the REVEAL Adult/Adolescent and Pediatric Trials Evaluating TSHA-102

Core Insights - Taysha Gene Therapies announced positive clinical data for TSHA-102, a gene therapy for Rett syndrome, showing a 100% responder rate in patients aged 6-21 years, with all patients gaining or regaining at least one developmental milestone post-treatment [1][2][5] - The FDA has provided written alignment on the pivotal Part B trial design for TSHA-102, which is expected to begin in Q3 2025 [1][4][12] - The analysis of natural history data indicates that patients aged six years and older are in a developmental plateau, with a likelihood of gaining new milestones being exceedingly low without treatment [1][6] Company Overview - Taysha Gene Therapies is a clinical-stage biotechnology company focused on AAV-based gene therapies for severe monogenic diseases of the CNS, with TSHA-102 as its lead program targeting Rett syndrome [8][10] - TSHA-102 is designed as a one-time treatment that delivers a functional form of the MECP2 gene to address the genetic root cause of Rett syndrome [8][9] Clinical Trial Details - The pivotal Part B trial will be a single-arm, open-label study with an intended enrollment of 15 patients, assessing developmental milestone gain/regain [1][6] - The primary endpoint of the trial is the gain or regain of at least one defined developmental milestone, with independent central raters evaluating outcomes based on video evidence [6] - Safety data from the ongoing REVEAL Phase 1/2 trials indicated no treatment-related serious adverse events or dose-limiting toxicities [1][5][6] Efficacy and Safety Findings - In the REVEAL Part A trial, 100% of patients treated with TSHA-102 achieved developmental milestones, with high-dose cohorts showing faster and more pronounced improvements compared to low-dose cohorts [1][5][6] - Improvements were observed across multiple clinician-assessed outcome measures, including the Revised Motor Behavior Assessment and Clinician Global Impression – Improvement [6] Future Plans - The company plans to submit the pivotal trial protocol and statistical analysis plan as an amendment to the IND application within the current quarter [2][12] - Taysha anticipates initiating pivotal trial activities in Q3 2025, following FDA guidance [1][12]