A new early-stage clinical trial reported in the New England Journal of Medicine found that three drug-resistant epilepsy patients experienced more than 90% seizure reduction per month after receiving gene-laden viruses infused directly into seizure-source brain tissue. The approach combines targeted gene therapy with a medication switch, described as chemogenetics, allowing clinicians to modulate treatment potency. The patients had hippocampal sclerosis on one side and were treated with a system designed so neurons respond to clozapine, acting like a dimmer rather than an on-or-off gene therapy effect. Investigators reported no serious side effects in the small cohort. Neurology teams will focus on scalability, long-term safety, and whether improved outcomes extend beyond the small number of participants and follow-up duration reported so far.