First Patient dosed in final phase of Taysha’s TSHA-102 trial
Taysha Gene Therapies announced this week that they have dosed the first patient of their REVEAL Pivotal (phase three) trial. The patient was dosed in the fourth quarter of 2025.
What does this mean?
The REVEAL trial tests TSHA-102 (A one-off gene therapy treatment given via an injection in the spinal canal) on patients aged between six and twenty two.
This ‘Pivotal’ phase is the final test of a new treatment to make sure it really works and is safe. If the results are positive, this is the trial that can lead to the treatment being approved for patients.
We’re at this stage earlier than expected because, in October, the FDA granted TSHA-102 “Breakthrough Therapy Status,” which allows trials to go ahead faster, and more efficiently. The FDA only grants this status to trials where early results show a treatment could be much better than anything we have now.
In the earlier trial, All 12 children and young people who got TSHA-102 gained or regained at least one skill or milestone
Additionally, Taysha is conducting an ASPIRE trial, testing the treatment on girls with rett aged two to four. Taysha will submit at least three months of safety and efficacy data from this trial, which they hope will support approval for the treatment for all patients with Rett aged two and over.
Sean P. Nolan, Chairman and Chief Executive Officer of Taysha said: “With an estimated 15,000 to 20,000 patients affected by Rett syndrome across the U.S., EU and U.K. and compelling REVEAL Part A clinical data, we see a significant opportunity to redefine the treatment paradigm for this devastating disease with high unmet need.”
What happens next?
- Taysha expects to finish dosing all patients in the REVEAL and ASPIRE trials in the second quarter of 2026.
- Taysha expects to release longer-term safety and efficacy data from Part A of the REVEAL Phase ½ trials in the first half of 2026.
Our message to families
Whilst TSHA-102 is still in clinical trials, this is another positive step. It shows the programme is moving forward and that treatments are getting closer.
At Reverse Rett, we will keep:
Sharing updates in clear language
Supporting families to understand what’s happening
Pushing for faster, fairer access to treatments once they are proven to work