On 21 April, at the 2026 American Academy of Neurology (AAN) meeting, BlueRock Therapeutics, a wholly owned, independently operated subsidiary of Bayer AG, announced positive results from its Phase I open-label two-year study (NCT04802733) evaluating bemdaneprocel, an investigational stem cell-derived therapy, in Parkinson’s disease (PD). The study aimed to assess predefined safety, tolerability, and feasibility criteria at one year, with trends towards improvement or stability in clinical assessments observed through two years post transplantation. The trial met its primary endpoint, with bemdaneprocel proving to be generally well-tolerated, with treatment-emergent adverse events (TEAEs) being mild or moderate in severity and unrelated to the cell transplant.
Bemdaneprocel is an investigational cell therapy composed of human embryonic stem cell-derived midbrain dopaminergic neuron progenitor cells. In the trial, bemdaneprocel was injected bilaterally into the postcommissural putamen in a single surgical session. Prior to the procedure, participants were subject to a one-year immunosuppression regimen. Following study completion, all participants enrolled in a continued-evaluation study for assessment through five years post transplantation. There were 12 participants enrolled in the study, which had a median age of 67 years and the median time since PD diagnosis was nine years. The safety data displayed was positive. Through three years post-transplantation, 12 participants experienced 112 TEAEs, although they were mostly mild or moderate in severity and none were related to the transplanted cells. There were eight treatment-emergent serious adverse events reported, but all were unrelated to the transplanted cells or the prior immunosuppression. Furthermore, there were no deaths or graft-induced dyskinesias and no intracerebral hemorrhages or mass lesions were observed by magnetic resonance imaging (MRI). Secondary endpoints exploring efficacy included evidence of cell survival, and mean (SD) changes from baseline in patient-reported ON times without troublesome dyskinesia (+2.1 hours (3.2)), and OFF times were (−2.0 hours (3.2)), and MDS-UPDRS Part III ON scores (−5.7 points (7.5)) and OFF scores (−17.9 points (8.5)), all showing trends towards improvement.
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This clinical data indicates that bemdaneprocel may have a place in the PD treatment landscape and could potentially be the first ever disease-modifying cell therapy to enter the market. However, bemdaneprocel is not alone as a cell therapy in clinical development for PD and is likely to face competition from other cell therapies such as Aspen Neuroscience’s sasineprocel, which is in Phase II development. In a challenging clinical landscape where many have failed to show disease modification, both bemdaneprocel and sasineprocel are likely to face similar challenges to predecessors in demonstrating longer term disease halting or reversal effects. BlueRock will have to establish that its stem-cell derived therapy is a safe and viable long-term treatment throughout its development program. By doing so, it would be able to ensure bemdaneprocel is in the race to become the disease-modifying therapy of choice in the future PD landscape. Competitors such as Aspen Neuroscience’s sasineprocel, an autologous induced pluripotent stem cell (iPSC)-derived dopaminergic neuron precursor cell (DANPC) therapy, have also exhibited promising safety data, as well as early cell survival. The challenge for both these therapies, is that they must address immunogenicity issues to reach the latter stages of development.
In summary, the longer-term trial results suggest that bemdaneprocel demonstrates a promising safety profile and early clinical benefits in patients with PD, supported by both functional and imaging evidence. While these findings highlight its potential as a novel, first‑in‑class stem cell‑derived therapy, its ultimate success will depend on proving disease modifying effects in larger Phase III trials, as well as differentiation from other cell therapies in development, which will determine its positioning in the PD treatment paradigm.
