Taysha Gene Therapies Inc (NASDAQ:TSHA) shares rose 3.6% in premarket trading Monday after the company announced completion of dosing in its pivotal study for Rett syndrome and published longer-term clinical follow-up findings.
The company said it has completed dosing of 17 patients in the REVEAL pivotal trial evaluating TSHA-102. Management outlined a timetable that expects topline results from a 6-month interim analysis, along with FDA feedback on the Biologics License Application pathway, in the first half of 2027.
Safety across the program remains a visible focus. Taysha reported that TSHA-102 was generally well tolerated with no treatment-related serious adverse events or dose-limiting toxicities recorded as of the June 2026 data cutoff. That safety assessment covers REVEAL Phase 1/2 and pivotal trials and represents a total of 29 patients.
Clinical efficacy signals were highlighted from REVEAL Part A. In that cohort, 100% of patients aged 6 to 21 years either gained or regained at least one developmental milestone by 12 months after treatment. The 12 patients in that analysis collectively showed 310 functional gains at 12 months or longer post-treatment - an average of roughly 26 gains per patient. Those gains include 31 developmental milestones and 279 additional skill gains or improvements.
Longer-term follow-up data, the company said, indicate a durable and deepening treatment effect at 12 months or more after dosing, with functional improvements accumulating across core disease domains. Taysha reported that developmental milestone gains rose by 69% from month 6 to month 12, and by 94% from month 6 to month 12 or longer after TSHA-102 administration.
Separately, Taysha noted progress in its ASPIRE program. Dosing was completed in an overenrolled ASPIRE trial that included four patients aged 2 to 5 years. The company expects to finish dosing in ASPIRE in July 2026. On the manufacturing side, Taysha anticipates completing its BLA-enabling Process Performance Qualification campaign for TSHA-102 in the fourth quarter of 2026.
Context for investors and markets
The updates affect multiple market and sector considerations. Clinical readouts and regulatory interactions shape near-term valuation drivers for the company, while safety and durability signals influence clinical de-risking. Manufacturing campaign timelines are relevant to commercialization readiness and regulatory filing preparations.
While the company disclosed positive signals and clearly defined near-term milestones, the path to a regulatory filing and final approval remains dependent on upcoming analyses and agency feedback.