Today, Taysha Gene Therapies announced positive clinical data from Part A of its REVEAL Phase 1/2 clinical trial of TSHA-102, an investigational gene therapy for Rett syndrome. In addition, the company shared details about the design of the trial’s next pivotal study phase, highlighting the essential role of our Rett community in shaping the path forward for treatment development.
KEY FACTS:
- Positive Clinical Data from Part A:
- 100% of patients in REVEAL Part A (N=10, 6-21 years) gained/regained ≥ one developmental milestone post TSHA-102
- High dose consistently outperformed low dose, with dose-dependent effects deepening over time
- No treatment-related SAEs or DLTs following low dose and high dose of TSHA-102
- Longitudinal Rett Syndrome Natural History Study Data Supported Taysha’s Pivotal Trial Design for TSHA-102
- Established patients ≥ six years of age are in a developmental plateau, with a ~0% likelihood of gaining/regaining developmental milestones across the core functional domains of Rett syndrome
- FDA supports single-arm, open-label pivotal trial with a primary endpoint of developmental milestone gain/regain with each patient serving as their own control
A Milestone Rooted in Community-Driven Data
The Rett Syndrome Natural History Study (NHS), launched in 2006 with support from the National Institutes of Health (NIH) and key contributions from IRSF, remains the most comprehensive effort ever undertaken to understand the progression of Rett syndrome. With 15 years of clinical data from more than 1,000 participants, the NHS provides critical insights into how Rett changes over time.
This study represents more than a research milestone—it is a testament to the families and clinicians who participated and contributed over many years to deepen our collective understanding of Rett syndrome. We extend our heartfelt thanks to each of them. IRSF is proud to serve as stewards of this data, working closely with researchers and clinicians, including the original team who now serve as the IRSF NHS Governance committee, to ensure this resource continues to drive progress. The use of NHS data to help design outcome measures for this pivotal clinical trial signals a new era of patient-informed treatment development.
The Ongoing Importance of the IRSF Rett Syndrome Registry
The progress reflected in Taysha’s announcement is rooted in years of foundational research and in the participation of families who made that research possible. Today, families can continue to drive progress through the IRSF Rett Syndrome Registry.
Built to extend the impact of the Natural History Study, the Registry is a longitudinal study that collects both clinician- and caregiver-reported data. This kind of rigorous, real-world information is essential for informing clinical trial design, validating outcome measures, and meeting the standards regulators require for treatment approval.
Looking Ahead: What’s Next for the REVEAL Study
What comes next is exciting. The FDA has advised Taysha to submit the pivotal Part B trial protocol as an amendment to their IND application, expected by the end of Q2, and to begin trial initiation activities in the pivotal portion of the REVEAL trial in Q3. As part of their continued collaboration with the research community, Taysha will present data related to TSHA-102 at IRSF’s Rett Syndrome Scientific Meeting in Boston this June.
At the same time, it’s important to recognize that TSHA-102 is still an investigational treatment. Further study is needed, and FDA approval is not guaranteed. As with all clinical development, rigorous data and continued participation will be essential to moving this work forward.
The results shared today underscore what’s possible when research is informed by families and built on the kind of scientific infrastructure IRSF has long championed. From the Natural History Study to the IRSF Rett Syndrome Registry, this community has helped make progress like this possible. IRSF remains committed to advancing trailblazing research and ensuring that every step toward new treatments reflects the real needs of those living with Rett syndrome.