Bemdaneprocel is an investigational therapy currently under development for Parkinson’s disease (PD) comprising human embryonic stem cell-derived midbrain dopaminergic neuron progenitors; preclinical studies supported proof of concept and safety. At 12 months post transplantation, predefined safety and tolerability criteria were met, and trends towards clinical benefit were observed.

To report the safety of bemdaneprocel and its impact on clinical outcomes in participants with PD through 24 months post transplantation.

In this Phase 1, open-label, 24-month, non-controlled study (exPDite, NCT04802733), 12 participants with PD received a low dose (n=5; 0.9 million cells/putamen) or high dose (n=7; 2.7 million cells/putamen) of bemdaneprocel injected using a cannula bilaterally into the postcommissural putamen during a single surgical session under general anesthesia. A 12-month immunosuppression regimen began intraoperatively.

Participants (N=12) were median 67.0 years of age, 75% male, and 67% White. Median time since PD diagnosis was 9.0 years. At 24 months post transplantation, 12 participants experienced 89 treatment-emergent adverse events (low dose, 43; high dose, 46); most were mild or moderate in severity. Three treatment-emergent serious adverse events, all unrelated to bemdaneprocel, were reported: hospitalizations due to COVID-19 (low dose), gastrointestinal hemorrhage (high dose), and a hospitalization due to seizure 1 day after surgery (high dose) considered possibly related to surgery. No deaths, discontinuations, or graft-induced dyskinesias occurred. In the high-dose cohort, MDS-UPDRS Part III OFF scores, and patient-reported ON times without troublesome dyskinesia and OFF times, indicated a continuing trend toward improved clinical assessments. Results in the low-dose cohort indicated stability or mild improvement.

Bemdaneprocel demonstrated a favorable safety profile and trended toward clinical benefit or stability through 24 months post transplantation. All participants have enrolled in a continued-evaluation study (NCT05897957). These results support the ongoing development of bemdaneprocel in a Phase 3 trial to evaluate efficacy and safety in people with PD.