BlueRock Therapeutics presented 36-month follow-up data from its Phase I Parkinson’s disease trial at the American Academy of Neurology annual meeting in April 2026, showing that a single transplant of bemdaneprocel — a cell therapy product derived from human embryonic stem cells — produced durable improvements in motor function sustained through three years of follow-up.
The open-label Phase I study (NCT04802733) enrolled patients with moderately advanced Parkinson’s disease and evaluated bemdaneprocel across low- and high-dose cohorts. In the high-dose cohort (n=7), patients demonstrated a mean reduction of 17.9 points on the MDS-Unified Parkinson’s Disease Rating Scale Part III at 36 months — a clinically meaningful change in a scale that measures motor signs such as tremor, rigidity, bradykinesia, and postural instability. The low-dose cohort showed more modest improvements.
Bemdaneprocel consists of dopaminergic progenitor cells — neurons committed to producing dopamine — manufactured from a master cell bank of human embryonic stem cells. The fundamental hypothesis of cell replacement therapy in Parkinson’s is that transplanting these progenitors into the putamen will restore dopamine signalling in the striatum, compensating for the progressive loss of dopaminergic neurons in the substantia nigra that underlies the disease’s motor manifestations.
Critically, the Phase I data show that transplanted cells are surviving and functioning at three years — a prerequisite for the cell replacement strategy to be clinically viable. Earlier foetal cell transplantation studies in the 1990s demonstrated proof-of-concept for dopamine cell survival but were limited by inconsistent outcomes and the practical constraints of foetal tissue sourcing. A standardised, stem cell-derived product addresses the consistency problem and is amenable to pharmaceutical-scale manufacturing.
The safety profile at 36 months remained acceptable. Treatment-emergent adverse events were mild to moderate in severity and were not attributed to the cell transplant itself. Immunosuppression was required in the trial period, as is standard for allogeneic cell transplantation, and management of this regimen is an ongoing area of clinical attention.
BlueRock, a subsidiary of Bayer, is now enrolling the Phase III exPDite-2 trial (NCT06944522), which will evaluate the high-dose bemdaneprocel regimen in a larger, randomised controlled design. A positive Phase III readout would represent a transformative moment for Parkinson’s therapeutics — the first disease-modifying treatment to demonstrably restore, rather than merely compensate for, lost neuronal function.
For researchers working on the neuroscience of glutamate and GABA systems, the bemdaneprocel results are a reminder that neurological disease can be addressed through multiple mechanistic paths. While cell replacement addresses the downstream deficit, upstream modulation of excitatory and inhibitory signalling remains a parallel and complementary therapeutic strategy across neurodegenerative and epileptic conditions.
