Why the sharp drop in share price of both Taysha and Neurogene...

Why the sharp drop in share price of both Taysha and Neurogene in response to their trial updates?

I expect that it is more related to Taysha reporting “significant challenges with AEs due to immunosuppressive regimen” rather than the the very early-stage efficacy results.

Both Taysha and Neurogene use Adeno-associated virus (AAV-9) vectors to deliver their gene therapies to where they need to go.

But the body can mount an immune response to the AAV vector which can potentially reduce the effectiveness of therapy and/or seriously impact the patient’s health and, in some cases, even cause death.

To counter this, gene therapy clinical trials now incorporate prophylactic immunosuppression regimens. Typically corticosteroids are used and sometimes a combination of drugs. Both Taysha and Neurogene have incorporated immunosuppression regimens in their clinical trials.

However, as mentioned in the Taysha announcement, there were significant, challenging side effects in response to the immunosuppression treatment experienced by both patients dosed in the paediatric trial.

Below is a link to a discussion of gene therapy which I posted early last year.

https://hotcopper.com.au/threads/neurogene-for-rett.7195113/page-7?post_id=65892502