The first in-human, open-label, randomized dose-escalation and dose-expansion REVEAL Phase 1/2 trials by Taysha Gene Therapies demonstrated sustained and new improvements in adults and children who were administered TSHA-102. In a follow-up for 52 weeks, one adult participant showed improved hand function, social interest, vocalization, and normalized sleep quality/duration. Another adult patient also improved posture and stability at 25 weeks post-treatment. Additionally, after 12 weeks of follow-up, one child participant was noticed to have gained the ability to identify an object from memory and follow commands. TSHA-102 was generally well-tolerated with no serious adverse events related to dose-limiting toxicities at follow-up.
Physician’s Perspective
Rett syndrome is caused by a pathogenic MECP2 mutation and is estimated to affect between 15,000 and 20,000 patients in the US, EU, and UK. The disorder commonly presents with a loss of communication and hand function, slowing or regressional development, motor and respiratory impairments, seizures, intellectual disabilities, and shortened life expectancies. Rett syndrome is one of the most common causes of severe intellectual disability. Currently, there is no approved disease-modifying therapy that treats the root genetic cause of the disease. A gene therapy such as TSHA-102 could target the genetic cause directly and result in definitive treatment.
Molecular Targets
Rett syndrome is caused by a mutation with the MECP2 gene encoding methyl CpG-binding protein (MeCP2) which is essential for regular synaptic function of the brain. TSHA-102 is a one-time lumbar intrathecal treatment that delivers a functional form of the MECP2 gene to cells in the CNS. The gene therapy uses novel miRNA-responsive auto-regulatory element (miRARE) technology to mediate levels of expression of MECP2 in CNS cells while lowering the risk of overexpression.