Human embryonic stem cell-derived dopaminergic cells for Parkinson's disease: a phase 1/2 open-label trial

Parkinson's disease (PD) is characterized by progressive loss of nigral dopaminergic neurons, resulting in disabling motor symptoms. Intracerebral transplantation of stem cell-derived dopaminergic progenitors to replace lost endogenous dopaminergic neurons offers a new potentially restorative therapeutic approach for PD. Here we report the 12-month primary safety end point and interim efficacy outcomes from a phase 1/2, open-label, multicenter trial evaluating STEM-PD, a cryopreserved, off-the-shelf dopaminergic progenitor product derived from human pluripotent stem cells. Eight individuals with moderate PD underwent bilateral intraputaminal transplantation at two escalating doses (n = 4 per cohort), followed by 12 months of immunosuppression. Seven participants completed 12-month follow-up; one participant died from a pulmonary infection. No serious adverse events were attributed to the cell product, no graft-induced dyskinesias were observed and serial magnetic resonance imaging showed no evidence of tumor formation. These findings support the feasibility and favorable safety profile of human pluripotent stem cell-derived dopaminergic progenitor transplantation in this early-phase study, with risks primarily associated with the immunosuppression regimen. Ongoing follow-up to 36 months will further evaluate durability, clinical outcomes and graft function. ClinicalTrials.gov identifier: NCT05635409 .