Taysha Raises $75 Million in Public Offering to Advance Gene Therapy for Rett Syndrome

Rare Daily Staff

One week after reporting positive data from phase 1/2 studies of its experimental gene therapy to treat Rett syndrome, Taysha Gene Therapies raised $75 million in an underwritten public offering to advance its pipeline of gene therapies targeting monogenic central nervous system disorders.

The company priced 14.4 million shares of its common stock at $2.25 per share and, in lieu of common stock to certain investors, pre-funded warrants to purchase 19 million shares of its common stock at $2.249 per pre-funded warrant, in each case before underwriting discounts and commissions. In addition, Taysha granted the underwriters a 30-day option to purchase up to an additional 15 percent of the shares of its common stock offered in the public offering at the public offering price, less the underwriting discount.

Taysha’s lead clinical program TSHA-102 is a self-complementary intrathecally delivered AAV9 investigational gene transfer therapy in development for Rett syndrome, a rare neurodevelopmental disorder with no approved disease-modifying therapies that address the genetic root cause of the disease.

Rett syndrome is caused by mutations in the X-linked MECP2 gene encoding methyl CpG-binding protein 2 (MeCP2), which is essential for regulating neuronal and synaptic function in the brain. The disorder is characterized by loss of communication and hand function, slowing and/or regression of development, motor and respiratory impairment, seizures, intellectual disabilities and shortened life expectancy.

On June 18, Taysha reported positive longer-term clinical data from the ongoing REVEAL phase 1/2 adolescent and adult trial and initial clinical data from the REVEAL phase 1/2 pediatric trial evaluating TSHA-102 in Rett syndrome, which showed durable improvements across consistent clinical domains in both adult and pediatric patients, including motor skills, communication/socialization, autonomic function, seizures, and an encouraging safety profile seen across adult (up to 52 weeks) and pediatric (up to 22 weeks) patients with different genetic mutation severity.

Longer-term data from two adult patients showed sustained and new improvements across multiple efficacy measures and clinical domains following the completion of steroid taper (patient one: sat unassisted for first time in over a decade, normalized sleep, stabilized seizures; patient two: improved hand stereotypies and breathing, seizure-free for 8.5 months at 25 percent lower anti-seizure medication).

Initial data from first two pediatric patients showed improvements across multiple efficacy measures and clinical domains, with early evidence of developmental gains (patient one: improved hand function, grasp and gross motor coordination, gained visual reception and receptive language skills; patient two: gained ability to stand up from chair and walk up a stair, increase in seizure-free days).