Bemdaneprocel embryonic stem-cell dopamine neurons

The research record

This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".

Who

Viviane Tabar and Lorenz Studer (Memorial Sloan Kettering) with BlueRock/Bayer (bemdaneprocel). Published in Nature, April 2025.

What happened

Phase 1 (NCT04802733), open-label: 12 patients with cryopreserved bemdaneprocel cells grafted into both putamens, in two cohorts: low dose (0.9 million cells, n = 5) and high dose (2.7 million cells, n = 7). All had one year of immunosuppression. The trial met its safety aims at one year, with no adverse events related to the cell product. At 18 months, putamen F-DOPA PET uptake had risen, indicating graft survival. The motor exam off medication (MDS-UPDRS Part III) improved by an average of 23 points in the high-dose cohort, with no control group. There were no graft-induced dyskinesias. In July 2026 the European STEM-PD trial (landmark 74) reported similar early results. The Kyoto iPSC trial, published in the same month, has its own file: landmark 300.

Why it moved us toward a cure

This is the first standardised, scalable source of replacement neurons, built on the recipe in landmark 17 and a successor to the fetal grafts of landmark 3: a route to restoring what was lost, not just slowing further loss. Bemdaneprocel is now in a sham-controlled Phase 3 (exPDite-2, 102 people planned; landmark 158).

Outcome

Advanced, with a pivotal trial underway. Caveat: the grafts restore dopamine but do not stop the underlying disease, and landmark 8 shows grafts can eventually be invaded.

Sources

• Tabar et al., Nature 2025;641:978–983, DOI 10.1038/s41586-025-08845-y (DOI link; PMID 40240592; abstract read via Europe PMC)
• Bayer: Phase 3 first patient
• STEM-PD, Nat Med 2026
• ClinicalTrials.gov NCT06944522 (exPDite-2; API checked 19 Oct 2026: Phase 3, 102 planned, recruiting)
• Not yet verified: the Phase 3 first-patient date (the Bayer release is dated 22 Sep 2025 per search results, and an AAN abstract puts the first surgery in August 2025; the registry start is 17 Jun 2025; the Bayer page itself would not load); the Nature full text beyond the abstract (so the 23-point figure has no confidence interval here).