Taysha completes dosing in pivotal Rett syndrome trials, raises $230 million
The company said topline results from a six-month interim analysis and FDA feedback on the BLA path for TSHA-102 are expected in the first half of 2027.
Taysha Gene Therapies reported on August 11, 2026 that it has finished dosing all patients in the REVEAL pivotal trial, enrolling a total of 17 individuals in the developmental plateau population of Rett syndrome treated with TSHA-1021. The trial is a single-arm, open-label study testing a single intrathecal high dose of TSHA-102 (1x10^15 total vector genomes) in females aged 6 to under 22, with a primary endpoint measuring the percentage of patients who gain or regain at least one of 28 natural history-defined developmental milestones1. Taysha said the study includes a six-month interim analysis, expected once all 17 patients complete six months of follow-up, that may support a Biologics License Application submission1.
The company also completed dosing in the ASPIRE trial, treating four Rett syndrome patients aged 2 to under 4 with a dose scaled for lower brain volume in that age group1. Taysha said ASPIRE is meant to support a BLA covering patients aged 2 and older, with at least three months of ASPIRE safety data included and efficacy for the 2 to under 6 age group extrapolated from REVEAL pivotal data1. Across all trials, TSHA-102 has shown no severe treatment-related serious adverse events or dose-limiting toxicities in 33 patients as of the August 2026 data cutoff1.
Taysha said it plans to discuss the interim data and BLA pathway next steps with the FDA, targeting topline results and regulatory feedback in the first half of 20271. It also expects to complete a BLA-enabling process performance qualification manufacturing campaign in the fourth quarter of 20261.
On manufacturing, Taysha said it expanded its agreement with Catalent, under which Catalent will handle GMP manufacturing and commercial supply of TSHA-102 at its licensed gene therapy site in Harmans, Maryland, and is set to be Taysha's lead commercial manufacturing partner if the therapy is approved1.
On financing, the company reported $455.4 million in cash and equivalents as of June 30, 2026, reflecting $230.0 million in gross proceeds from a June 2026 follow-on offering that included full exercise of the underwriters' overallotment option1. Taysha said its current cash is expected to fund planned operating expenses into the second half of 20281.
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