Commenced site activation for REVEAL pivotal trial in accordance with previously aligned upon key design elements, following receipt of No Objection Letter (NOL) from Health Canada and feedback from the FDA; patient enrollment anticipated to begin in Q4 2025 High dose and low dose TSHA-102 continue to be generally well tolerated with no treatment-related SAEs or DLTs in the 12 patients treated in Part A of REVEAL Phase 1/2 trials as of August 2025 data cutoff Part A data from REVEAL Phase 1/2 trials present ...

Core Insights - Taysha Gene Therapies is advancing its TSHA-102 program for Rett syndrome, focusing on the potential to improve developmental milestones and quality of life for patients [2][3] - The company will present recent updates on TSHA-102 at the 2025 International Rett Syndrome Foundation Scientific Meeting in Boston [2][4] - TSHA-102 is a gene therapy designed to address the genetic root cause of Rett syndrome by delivering a functional form of the MECP2 gene [5] Company Overview - Taysha Gene Therapies is a clinical-stage biotechnology company specializing in AAV-based gene therapies for severe monogenic diseases of the central nervous system [7] - The company has received multiple designations from the FDA for TSHA-102, including Regenerative Medicine Advanced Therapy and Fast Track designations [5] - Taysha aims to address significant unmet medical needs in the field of gene therapy, leveraging its experienced management team and proven AAV9 capsid technology [7] Disease Context - Rett syndrome is a rare neurodevelopmental disorder primarily affecting females, characterized by loss of communication, motor function, and intellectual disabilities [6] - The disorder is caused by mutations in the MECP2 gene, with an estimated 15,000 to 20,000 patients affected in the U.S., EU, and U.K. [6] - Currently, there are no approved therapies that modify the disease's genetic root cause, highlighting the importance of TSHA-102 [6]

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]

Core Insights - Taysha Gene Therapies has made significant regulatory and clinical progress with its TSHA-102 program for Rett syndrome, having reached alignment with the FDA on key elements of the pivotal Part B trial design [3][4] - The FDA has advised the company to submit the pivotal Part B trial protocol and statistical analysis plan as an amendment to the IND application, which is expected to expedite study initiation and registration [3][4] - TSHA-102 has shown to be generally well tolerated in patients, with no treatment-related serious adverse events or dose-limiting toxicities reported in the initial cohorts [4] Regulatory Progress - The company achieved alignment with the FDA on the pivotal Part B trial design for TSHA-102, following discussions under the Regenerative Medicine Advanced Therapy (RMAT) pathway [4] - The FDA's guidance allows Taysha to submit the trial protocol directly as an IND amendment, eliminating the need for a formal end-of-phase meeting, which may accelerate the process [3][4] Clinical Data - As of April 10, 2025, TSHA-102 has been administered to 10 patients (6 in the high dose cohort and 4 in the low dose cohort) across two REVEAL Phase 1/2 trials, with no serious adverse events or dose-limiting toxicities reported [4] - A comprehensive update on the pivotal trial design, natural history data analysis, and clinical data from the REVEAL trials is anticipated in Q2 2025 [4][13] Financial Highlights - For Q1 2025, research and development expenses were $15.6 million, down from $20.7 million in Q1 2024, primarily due to reduced manufacturing activities [7] - General and administrative expenses increased to $8.2 million in Q1 2025 from $7.1 million in Q1 2024, attributed to higher compensation and legal fees [8] - The net loss for Q1 2025 was $21.5 million, or $0.08 per share, compared to a net loss of $24.1 million, or $0.10 per share, in Q1 2024 [9][17] Cash Position - As of March 31, 2025, Taysha had $116.6 million in cash and cash equivalents, which is expected to support operations into Q4 2026 [9][19] Upcoming Events - Taysha will present three abstracts related to TSHA-102 at the 2025 International Rett Syndrome Foundation Scientific Meeting scheduled for June 9-11, 2025 [4][5]