STEM-PD trial protocol - A multi-centre, single-arm, first-in-human, dose-escalation trial

Sep 29, 2026

STEM-PD is a multi-centre, single-arm, dose-escalation, first-in-human ATIMP trial in Europe evaluating the safety, tolerability, and feasibility of intraputamenal transplantation of RC17 human embryonic stem cell-derived dopaminergic neural progenitors for moderately advanced Parkinson’s disease. Eight participants from two sites in Sweden and the UK will be recruited. Primary outcomes assess adverse and serious adverse events plus absence of space-occupying cranial MRI lesions over the first 12 months. Secondary and exploratory outcomes include clinical measures, anti-Parkinson’s medication changes, and graft survival using positron emission tomography at 12 and 36 months.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages12

Reading Time30 min

AccessFree to download

Abstract

Introduction

Methods and analysis

Strengths and limitations of this study

Ethics and dissemination

Open access Protocol STEM-PD trial protocol: a multi-centre, single-arm, first-in-human, doseescalation trial, investigating the safety and tolerability of intraputamenal transplantation of human embryonic stem cell-derived dopaminergic cells for Parkinson’s disease Gesine Paul,1,2 Hjalmar Bjartmarz,3 Anders Björklund,4 Emma Cutting,5,6 Amy Evans,6 Bronwen Harry,5,6 Oskar Hansson,7 Saeed Kayhanian ,6,8 Agnete Kirkeby,9,10 Nicholas Lao-Kim,11 Olle Lindvall,12 Jenny Nelander,4 Paola Piccini,13 Ruben Smith,4 Susann Ullén,14 Trinette Van Vliet,14 Hakan Widner,1 Malin Parmar,4 Roger A Barker6,8 To cite: Paul G, Bjartmarz H, Björklund A, et al. STEM-PD trial protocol: a multi-centre, singlearm, first-in-human, doseescalation trial, investigating the safety and tolerability of intraputamenal transplantation of human embryonic stem cellderived dopaminergic cells for Parkinson’s disease. BMJ Open 2025;15:e107597 . doi:10 . 1136/ bmjopen-2025-107597 ► Prepublication history and additional supplemental material for this paper are available online. To view these files, please visit the journal online ([https://doi.org/10.1136/](https://doi.org/10.1136/)[ ](https://doi.org/10.1136/)[bmjopen-2025-107597](bmjopen-2025-107597)) . Received 07 July 2025 Accepted 24 November 2025 © Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY. Published by BMJ Group. For numbered affiliations see end of article. Correspondence to Professor Roger A Barker; [rab46@cam.ac.uk and](rab46@cam.ac.uk and)[ ](rab46@cam.ac.uk and)Professor Gesine Paul; [gesine.paul-visse@med.lu.se](gesine.paul-visse@med.lu.se) ABSTRACT Introduction Parkinson’s disease (PD) is a common neurodegenerative disease, which has extensive pathology that critically includes the loss of midbrain dopaminergic neurons. This loss leads to debilitating motor features such as bradykinesia and rigidity, as well as some nonmotor symptoms. Intracerebral dopamine cell transplants have been explored for many years as a new approach to treating PD and initially used human fetal ventral mesencephalic tissue with inconsistent results, related in part to major logistical challenges in sourcing enough tissue of the right quality and the limited possibilities for quality control and standardisation. Dopaminergic neurons can now be derived reliably from human stem cell sources, which may overcome some of the challenges associated with fetal tissue transplantations. Methods and analysis STEM-PD is a multi-centre, single-arm, dose-escalation, first-in-human advanced therapy investigational medicinal product (ATIMP) trial in Europe using a cell product that consists of dopaminergic neural progenitors derived from the RC17 human embryonic stem cell line. The aim of the study is to assess the safety, tolerability and feasibility of intraputamenal transplantation of this cell product inpatients with moderately advanced PD. Eight participants will be recruited from two sites, Skånes University Hospital (Lund, Sweden) and Cambridge University Hospital (Cambridge, UK) . The primary outcome of the trial is safety and tolerability, assessed by the number and nature of adverse events and serious adverse events, and the absence of space-occupying lesions on cranial MRI, in the first 12 months following transplantation. Secondary and exploratory outcomes, including clinical measures, changes in anti-Parkinson’s medication and measures of graft survival using positron emission tomography STRENGTHS AND LIMITATIONS OF THIS STUDY ⇒ First-in-human study to investigate the safety and tolerability of transplanting RC17 human embryonic stem cell-derived dopaminergic precursor cells into the brains of patients with Parkinson’s disease. ⇒ A trial working across two centres in different countries to show feasibility across sites. ⇒ The trial involves a single dose escalation after assessment of 6 months post-transplant safety data from a lower-dose cohort of four patients. ⇒

FAQs

What does the STEM-PD trial investigate in Parkinson’s disease?

It investigates the safety and tolerability of intraputamenal transplantation of human embryonic stem cell-derived dopaminergic neural progenitors (RC17 line) in patients with moderately advanced Parkinson’s disease.

How is the trial designed and how many participants will be recruited?

The trial is a multi-centre, single-arm, dose-escalation, first-in-human study. Eight participants will be recruited from two sites in Sweden and the UK.

What are the primary and key secondary outcomes?

Primary outcomes are safety and tolerability based on adverse and serious adverse events and the absence of space-occupying cranial MRI lesions in the first 12 months. Secondary and exploratory outcomes include clinical measures, changes in anti-Parkinson’s medication, and graft survival assessed using positron emission tomography.

Sep 29, 2026

Uploaded by Maya Linwood