Safety-boosting drug may weaken gene therapy efficacy in Dravet syndrome trial

Encoded Therapeutics studied a drug meant to improve the safety of gene therapy in children with Dravet syndrome, a severe genetic epilepsy.

In the trial of 21 participants, most received steroids as the standard immune suppressant, while a subset - including those on the highest dose - also received sirolimus, known as rapamycin, which is used to prevent organ transplant rejection.

The data showed that adding sirolimus may reduce immune reactions but also appeared to blunt the therapeutic effect of the gene therapy, raising concerns about its overall benefit.

The findings could have implications for other developers of neurological gene therapies, such as Sarepta and Regenxbio, who may need to weigh safety against efficacy.