STEM-PD trial

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

Region Skåne is the registered sponsor, with Lund University and Cambridge as collaborators (NCT05635409). Malin Parmar led the project, Gesine Paul (Paul-Visse) was principal investigator, Hjálmar Bjartmarz and Irina Grubor did the surgery, and Roger Barker (Cambridge) was clinical lead. The paper lists support from Novo Nordisk A/S, Lund's Multipark and StemTherapy, Swedish government and regional grants and the Swedish Research Council.

What happened

The first patient was grafted at Skåne University Hospital in February 2023 (reported 13 Feb). The product, STEM-PD, is made from the clinical-grade embryonic stem-cell line RC17. Four patients got 3.54 million cells per putamen and four got 7.08 million per putamen, each side injected along five tracts. All were followed for 36 months. The primary measures were adverse events in the first 12 months and absence of space-occupying masses on MRI; efficacy is judged at three years. Registry: Phase 1, non-randomised, enrolment 8, status active not recruiting.

The results paper (Paul et al., Nature Medicine 2026;32:3449–3457, published 9 July 2026) reports eight patients with moderate disease (median age 63, median duration 14.5 years), enrolled between 3 January 2023 and 13 September 2024. Seven completed 12 months. One high-dose patient died 10 weeks after surgery of disseminated fungal (aspergillus) lung infection that spread to the brain while on immunosuppression; the authors treat this as a risk of the immunosuppression, not of the cells. Three serious adverse events occurred in all, none attributed to the cell product. No graft-induced dyskinesias, and MRI showed no tumours. Dopamine PET (F-DOPA) showed focal uptake increases at 6 and 12 months. Six of seven substantially cut their dopamine medication: levodopa-equivalent dose fell 15.6% (low dose) and 27.5% (high dose) against baseline. There was no control group and no formal statistics. All received 12 months of immunosuppression (tacrolimus, azathioprine and steroids).

Why it moved us toward a cure

It is the European test of the cell recipe in landmark 72, and the second independent embryonic-stem-cell product in patients after the US trial in landmark 10. It also avoids the dyskinesia problem of fetal grafts (landmark 3).

Outcome

Open: the 12-month safety readout is in; the 36-month efficacy follow-up is expected near the registry's estimated study completion of November 2027 (the last patient was enrolled in September 2024). This is a small open-label safety study; whether the cells slow or reverse anything is unknown. Medication reduction needs controlled trials to interpret.

Sources

• Lund University, first patient (Feb 2023)
• Lund University, trial update (6 May 2024, updated 22 May 2025)
• Lund University, first results (9 Jul 2026)
• Paul et al., Nat Med 2026;32:3449–3457, DOI 10.1038/s41591-026-04525-0, PMID 42426223 (open-access full text, PMC13577911, read via Europe PMC 19 Oct 2026)
• ClinicalTrials.gov NCT05635409 (API checked 19 Oct 2026; last update 17 Dec 2025; start 30 Nov 2022, primary completion estimated Jan 2027, study completion Nov 2027)
• Not yet verified: exact graft dates for each patient (the paper gives enrolment dates); the paper's exact PET and motor-score numbers (only the medication figures were read in detail); the pending date is the registry's estimate.