Taysha Gene Therapies regains full rights to TSHA-102 program

Taysha Gene Therapies (TSHA) announced that the company has regained full rights to its lead TSHA-102 program in clinical evaluation for Rett syndrome. The 2022 option agreement between Astellas (ALPMY) and Taysha, which had granted Astellas the exclusive option to enter a negotiation period to obtain an exclusive license to TSHA-102 in Rett syndrome and certain rights with respect to change in control transactions involving Taysha, has expired. In accordance with the 2022 option agreement, Taysha delivered a TSHA-102 data package to Astellas in mid-2025 that contained the previously disclosed Part A REVEAL clinical data, initiating a 90-day review period for Astellas to elect to exercise an option to trigger exclusive negotiations for a transaction. These data were shared with the FDA as part of the application for, and subsequent receipt of, Breakthrough Therapy designation for TSHA-102. Following the expiration of the option agreement, Taysha now holds unencumbered rights to the TSHA-102 program. Taysha has finalized FDA alignment on the REVEAL pivotal trial protocol and statistical analysis plan, which includes a 6-month interim analysis that may serve as the basis for BLA submission. The REVEAL pivotal trial is a single-arm, open-label trial with each patient serving as their own control. A single intrathecal administration of high dose TSHA-102 will be evaluated in 15 females between the ages of 6 and less than 22 years in the developmental plateau population of Rett syndrome. The primary endpoint will assess response rate, defined as the percentage of patients who gain or regain one or more defined developmental milestone from a list of 28 across the core functional domains of communication, fine motor and gross motor, following dosing with TSHA-102. Selected milestones have a 0% to less than 6.7% likelihood of spontaneous gain/regain in the untreated Rett syndrome population aged greater than or equal to 6 years based on natural history data. Standardized milestone assessments will be administered and captured on video at pre- and post-treatment timepoints, with determination of milestone gain/regain by video-evidence review by independent, blinded central raters based on prespecified definitions of achievement for each milestone. Dosing of the first patient in the REVEAL pivotal trial has been scheduled for the current quarter.