On 22 June 2026, Taysha Gene Therapies provided an update on TSHA-102, an investigational gene therapy designed to address the root cause of Rett syndrome by delivering a functional copy of the MECP2 gene to cells in the brain and central nervous system.
Study progress
Dosing has been completed in the REVEAL Pivotal Study, which enrolled 17 participants aged 6 to 21 years. Once all participants have completed six months of follow-up, Taysha plans to review the interim results with the U.S. Food and Drug Administration (FDA) to discuss the next steps needed for potential approval. Initial pivotal study results and feedback from the FDA are expected in the first half of 2027.
Dosing in the ASPIRE Study, which is enrolling four participants aged 2 to under 4 years, is expected to be complete in July 2026.
Safety and tolerability
Across all 29 participants in the REVEAL Part A and Part B studies as of the June 2026 data cutoff, TSHA-102 was generally well-tolerated with no treatment-related serious adverse events. Side effects were generally mild to moderate, with the most common being elevated liver enzymes, an increase in protein in spinal fluid, and fever.
Functional gains observed
Taysha shared longer-term interim data from REVEAL Part A, in which 12 participants aged 6 to 21 years have now been followed for at least 12 months. While the data is interim and conclusions cannot yet be drawn, the early improvements seen across participants have been sustained, with additional functional gains achieved over time.
At 12 months or more after receiving TSHA-102, a total of 310 functional gains were observed across the 12 participants — an average of around 26 per person. These included:
- 31 developmental milestones across communication, hand use and mobility. All participants (100%) gained or regained at least one developmental milestone, as assessed by multiple independent experts using video evidence. Examples included speaking in phrases with meaning, using utensils to eat without assistance, and walking with support.
- 279 additional skill gains and improvements across communication, hand use, mobility, autonomic function and other Rett-related symptoms. Examples included improved motor skills and hand use, understanding and responding to questions, reduced or eliminated hand stereotypies, and decreased or eliminated breath-holding.
Functional gains were seen regardless of the participant’s age, severity or genotype.
How TSHA-102 works
TSHA-102 is administered as a one-time treatment through an intrathecal injection in the lower back — a minimally invasive procedure that delivers the therapy directly into the cerebrospinal fluid surrounding the brain and spinal cord. The therapy includes a built-in control mechanism designed to ensure that each cell receives the right amount of MeCP2 protein.
Looking ahead
Taysha has stated that its goal is to ensure TSHA-102 will be available to the broad Rett community, regardless of age, sex or clinical presentation, if it is approved. Final approval and labelling will be determined by regulatory authorities.
The company extended its gratitude to the individuals and families participating in the clinical studies and to the broader Rett syndrome community for their support.
More information is available on the Taysha Gene Therapies website. Details about the REVEAL and ASPIRE studies can be found on ClinicalTrials.gov (NCT05606614 and NCT07480564).
