To evaluate seizure control in transplanted epilepsy patients on calcineurin inhibitors (CNI).

One-third of people with epilepsy are drug-resistant, making them potential candidates for epilepsy surgery. Concerns about side effects and complications make surgery underutilized. An emerging alternative is transplantation of stem-cell-derived inhibitory interneurons, currently in human clinical trials. Transplantation is anticipated to require immunosuppression. CNIs are commonly used for post-transplant immunosuppression in other fields but can cause neurologic side effects including seizures. Understanding seizure control in people with epilepsy on CNIs is crucial in understanding possible impacts of novel stem cell therapies.

Patients with epilepsy who underwent transplantation and took CNIs were identified through chart review. Patients with provoked seizures, post-transplant first-time seizure onset, or those who did not survive one-year past transplant were excluded. Data collected included transplant type, seizure characteristics, ASMs, ASM levels, breakthrough seizures, and epilepsy management changes within a year of transplant. Descriptive statistics were used to analyze clinical characteristics of patients.

Out of 265 patients identified, 49 met inclusion criteria. Of these, 33% (16/49) of patients had breakthrough seizures after transplant, and 20% (10/49) of patients had an increase in seizure frequency after transplant. Of patients with breakthroughs seizures, 43% (7/16) were previously seizure-free and 56% (9/16) had therapeutic ASM levels when checked. Additionally, 90% (9/10) of patients with increased seizures had adjustments in their ASMs as a result, 50% (5/10) started an additional ASM, and only 1 patient discontinued CNIs. 

A clinically relevant proportion of epilepsy patients had breakthrough seizures and increased seizure frequency after transplantation. Most breakthrough patients were managed with ASM dose adjustments despite a majority not having subreference ASM levels. Comparison with transplanted epilepsy patients not on CNIs could help explore if CNIs impact seizure control.