A stem cell derived cell therapy for Parkinson's disease, bemdaneprocel, continued to ease motor symptoms and shorten daily off time two years after a single surgical implant, according to peer reviewed results from a 12 person Phase 1 trial published in the journal Neurology. The finding lands as a much larger, sham surgery controlled Phase 3 trial testing the same cells, exPDite-2, has begun dosing participants at sites in the United States, Canada and Australia, the first late stage test of a cell replacement approach in Parkinson's.
In the completed Phase 1 study, exPDite (NCT04802733), five participants received a low dose of 0.9 million cells per side of the putamen and seven received a high dose of 2.7 million cells per side, delivered in a single operation followed by 12 months of immunosuppression. At the 24 month mark, the high dose group had a mean reduction of 21.9 points on the MDS-UPDRS Part III motor score measured in the medication off state, compared with 8.3 points in the low dose group, and reported roughly 1.8 more hours a day of well controlled on time and 1.9 fewer hours of off time on patient diaries, Bayer and BlueRock Therapeutics reported alongside the published data. Twelve participants experienced 89 treatment emergent adverse events through 24 months, mostly mild or moderate; three serious events, including a seizure the day after surgery, were not attributed to the cell therapy itself, and no deaths, discontinuations or dyskinesias caused by the graft were recorded.
What the Phase 1 data cannot show is whether those improvements came from the transplanted cells rather than from the surgery itself, natural fluctuation in symptoms, or participants and raters knowing treatment had been given: the study had no placebo or sham surgery comparison group and enrolled only 12 people. That gap is the explicit purpose of exPDite-2 (NCT06944522), a randomized, double blind, sham surgery controlled trial enrolling about 102 adults with Parkinson's, assigned two to one to bemdaneprocel or a simulated procedure. Participants must be 45 to 75 years old, four to twelve years past diagnosis, still responsive to levodopa, and experiencing at least 2.5 hours of daily off time; the primary endpoint is change in on time without troublesome dyskinesia after 18 months.