Taysha Gene Therapies shares fall on gene therapy trial update

Taysha Gene Therapies Inc. shares fell sharply on Tuesday after the company disclosed a partial clinical hold on its gene therapy trial for Rett syndrome by U.S. regulators.

The Dallas-based biotech said the U.S. Food and Drug Administration (FDA) imposed the hold on its IND application for TSHA-102, a potential treatment for Rett syndrome, a rare neurological disorder. The agency requested additional preclinical data before allowing further human trials to proceed.

Taysha did not specify a timeline for resolving the hold but noted it is working with the FDA to address the agency’s concerns. The company said it expects to provide an update once more information is available.

Shares of Taysha were down 15% at $3.20 in premarket trading, extending losses from Monday’s close of $3.76. The decline reflects investor concerns over regulatory delays, which could impact the timeline for commercializing the therapy.

Rett syndrome primarily affects girls and has no approved treatments. Taysha’s gene therapy aims to address the underlying genetic cause of the condition by delivering a functional copy of the MECP2 gene. The FDA’s partial hold does not affect ongoing preclinical studies or other pipeline programs.

Analysts tracking the stock cited the regulatory uncertainty as a key risk factor. The partial hold follows previous setbacks for Taysha, including a prior clinical hold in 2023 that was later lifted after additional data was submitted.

The company has not provided revised guidance for the trial’s progress but emphasized its commitment to advancing the program despite the current challenges.