Full Press Release Details
Taysha Gene Therapies Presents Preclinical Data on TSHA-102 for Rett Syndrome Demonstrating Cellular
Regulation of MeCP2 Expression in Key Mouse Models at the American Society of Gene and Cell Therapy 26th Annual Meeting
New preclinical data after neonatal administration in wild-type mice showed no detectable impact on survival, neurobehavioral functions and
overall health, suggesting TSHA-102, engineered with novel miRARE technology, avoided toxic overexpression of MeCP2 within cells already expressing MeCP2
Data reinforce previous findings in Mecp2 /Y knockout mice demonstrating TSHA-102 regulated cellular MeCP2 levels and significantly improved survival, overall neurobehavioral function and growth
Data in neonatal mouse models highlight the potential of the miRARE technology to enable safe expression levels of MeCP2, which may address
the risks associated with both under and overexpression of MeCP2 resulting from the mosaic pattern of MECP2 silencing in females with Rett syndrome
Dosing of the first adult patient with TSHA-102 in the Phase 1/2 REVEAL trial in Rett syndrome is
DALLAS May 19, 2023 Taysha Gene Therapies, Inc. (Nasdaq: TSHA), a clinical-stage gene therapy company focused
on developing and commercializing AAV-based gene therapies for the treatment of monogenic diseases of the central nervous system (CNS), today presents preclinical data from neonatal mouse models on TSHA-102 for Rett syndrome, including new data in wild-type mice, at the American Society of Gene and Cell Therapy (ASGCT) 26th Annual Meeting. TSHA-102 utilizes a miniMECP2 gene and a novel miRNA-Responsive Auto-Regulatory Element (miRARE) technology designed to regulate cellular MECP2 expression. In a Taysha-sponsored study, the safety and
efficacy of TSHA-102 were explored in both neonatal wild-type and Mecp2 /Y knockout mice, respectively. Preclinical in-life data on early intervention of TSHA-102 in neonatal mice suggest miRARE enables the expression of the MeCP2 protein in deficient CNS cells while preventing toxic
overexpression within cells expressing normal levels of MeCP2.
These encouraging new preclinical data in wild-type mice indicate that TSHA-102, engineered with our miRARE technology, avoided overexpression of MeCP2 within cells already expressing MeCP2, while maintaining normal survival, neurobehavioral function and overall health,
said Sukumar Nagendran, M.D., President, and Head of R&D. These new data augment previous findings in the Mecp2 /Y knockout mouse model, suggesting that THSA-102 regulated expression of MECP2 in both normal and MECP2 deficient cells, which is critical given that Rett syndrome represents such a challenging case for human gene therapy because the
therapeutic window for MECP2 transgene expression is narrow. Either MECP2 deficiency or duplication can lead to serious neurodevelopmental disease. We believe these new data from neonatal wild-type mice support the potential of miRARE
to enable the optimal amount of MeCP2. This would be critical to modulating the cellular expression of MeCP2 in an appropriate, clinically relevant manner, given the mosaic pattern of MECP2 silencing characteristic of female patients with
Sarah Sinnett, Ph.D., University of Texas Southwestern Medical Center, Co-Inventor of miRARE
technology, added, TSHA-102 pairs a therapeutic gene with miRARE, all within a single vector genome. The miRARE technology was designed to mitigate the risk of MeCP2 overexpression through a
post-transcriptional feedback repression mechanism. We are pleased that miRARE permitted efficacy in Mecp2 /Y mice without compromising safety in wild-type mice. Importantly, these
findings could translate into clinical benefits for treating patients with Rett syndrome.
Preclinical data in neonatal wild-type mice suggest miRARE suppressed toxic overexpression after early
intervention with TSHA-102:
This builds on prior preclinical data in neonatal
Mecp2 /Y knockout mice showing miRARE regulated MECP2 expression levels in deficient CNS cells with early intervention of TSHA-102:
TSHA-102 is a self-complementary intrathecally delivered AAV9 investigational gene transfer therapy in
clinical evaluation for Rett syndrome, a rare genetic neurodevelopmental disorder caused by mutations in the X-linked MECP2 gene. TSHA-102 is currently being
evaluated in the Phase 1/2 REVEAL trial in adult patients with Rett syndrome. The dosing of the first adult patient with TSHA-102 is expected in Q2 2023, with initial available clinical data, primarily on
safety, anticipated thereafter in Q2 2023. TSHA-102 has received Orphan Drug and Rare Pediatric Disease designations from the U.S. Food and Drug Administration (FDA) and has been granted Orphan Drug
designation from the European Commission for the treatment of Rett syndrome.
About Taysha Gene Therapies
Taysha Gene Therapies (Nasdaq: TSHA) is on a mission to eradicate monogenic CNS disease. With a singular focus on developing curative medicines, we aim to
rapidly translate our treatments from bench to bedside. We have combined our team s proven experience in gene therapy drug development and commercialization with the world-class UT Southwestern Gene Therapy Program. Together, we leverage our
fully integrated platform with a goal of dramatically improving patients lives. More information is available at www.tayshagtx.com.
Forward-Looking Statements
This press release contains
forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as anticipates, believes, expects, intends, projects,
plans, and future or similar expressions are intended to identify forward-looking statements. Forward-looking statements include statements concerning the potential of our
product candidates, including TSHA-102, to positively impact quality of life and alter the course of disease in the patients we seek to treat, our research, development and regulatory plans for our product
candidates, the potential for these product candidates to receive regulatory approval from the FDA or equivalent foreign regulatory agencies, and whether, if approved, these product candidates will be successfully distributed and marketed and the
potential market opportunity for these product candidates. Forward-looking statements are based on management s current expectations and are subject to various risks and uncertainties that could cause actual results to differ materially and
adversely from those expressed or implied by such forward-looking statements. Accordingly, these forward-looking statements do not constitute guarantees of future performance, and you are cautioned not to place undue reliance on these
forward-looking statements. Risks regarding our business are described in detail in our Securities and Exchange Commission ( SEC ) filings, including in our Annual Report on Form 10-K for the
full-year ended December 31, 2022, which is available on the SEC s website at www.sec.gov. Additional information will be made available in other filings that we make from time to time with the SEC. Such risks may be amplified by the
impacts of the COVID-19 pandemic. These forward-looking statements speak only as of the date hereof, and we disclaim any obligation to update these statements except as may be required by law.
Director, Head of Corporate Communications
Canale Communications