Brain cell therapy to reduce seizures in hard-to-treat temporal lobe epilepsy

Plain-English translation of NCT05135091 on ClinicalTrials.gov ↗ · Source last updated March 2026 · Translation generated June 2026 · How we translate trials

Phase 3 — Testing in thousands of people, comparing the treatment against what doctors currently use. This is the last big step before approval.

What is this trial?

This study is testing a new treatment called , which involves transplanting special brain cells directly into the area where seizures start. These cells naturally produce a calming chemical in the brain that helps prevent seizures from happening. The treatment is designed for people with mesial temporal lobe epilepsy—a specific type of epilepsy focused in one part of the brain—who haven't gotten relief from two or more anti-seizure medications.

For many people with this type of epilepsy, standard medications don't work well enough, and seizures continue to disrupt their lives. This medication offers a completely new approach by using the body's own cellular biology to calm the brain region where seizures happen, rather than relying only on pills.

Do you qualify?

You likely qualify if…

you are between 18 and 75 years old
you have been diagnosed with mesial temporal lobe epilepsy caused by a single location in one hippocampus
you have tried at least two anti-seizure medications at adequate doses without good control
you currently have at least 2 disabling seizures per month, despite being on stable medication
you have been on a stable dose of anti-seizure medication for at least one month before screening

You likely don't qualify if…

you have a history of status epilepticus (prolonged, life-threatening seizures) in the past 3 years
you have evidence that seizures are coming from multiple areas of the brain or outside the hippocampus
you have a weakened immune system or primary immunodeficiency disorder
you have had a previous brain surgery for epilepsy (lobectomy or LITT procedure)
you are pregnant, breastfeeding, or have had suicide attempts in the past 3 years

What participation looks like

If you qualify and are enrolled, you will undergo a one-time procedure where the treatment cells are guided into your brain using imaging (CT or MRI). You'll then take immunosuppressant medication for one year to help the new cells survive. Over the next 2 years, you'll have regular visits to check on safety and how many seizures you're having. After that, you'll continue with phone calls and annual visits through year 15, so researchers can track how well the treatment is working over time.

AI-generated summary from trial data · Jun 1, 2026 · Not medical advice

Trial locations(33 sites)

United States

Mayo Clinic Arizona Epilepsy Center, Phoenix, Arizona

Banner-University of Arizona Medical Center Tucson Comprehensive Epilepsy Program, Tucson, Arizona

University of Arkansas for Medical Sciences, Little Rock, Arkansas

University of Southern California Keck Hospital, Los Angeles, California

University of California Los Angeles, Los Angeles, California