BlueRock's Stem-Cell Therapy for Parkinson's Holds Up Three Years After a Single Dose

A single dose of an experimental stem-cell therapy has produced sustained motor improvements in patients with advanced Parkinson's disease three years after treatment, according to follow-up data presented at the American Academy of Neurology's 2026 Annual Meeting in Chicago. The therapy, called bemdaneprocel and developed by BlueRock Therapeutics, a Bayer subsidiary, transplants laboratory-grown dopamine-producing nerve-cell progenitors directly into the patient's brain — a long-pursued strategy aimed at replacing the dopamine neurons that Parkinson's slowly destroys.

In the open-label Phase 1 trial, twelve patients received either a low or a high dose of the cells, surgically implanted into the putamen, a region of the brain heavily affected by the disease. Three years on, the high-dose group showed a "trend towards improvement" in scores on the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) in both medicated and unmedicated states, BlueRock reported. Patients in that group spent less time each day in "off" periods — when their symptomatic medication has worn off — and more time in "on" periods without the troublesome involuntary movements known as dyskinesia. The low-dose group held steady, a notable result in a degenerative disease in which decline is the expected course.

No serious adverse events related to the therapy were reported. "What we are most interested in is the durability," said BlueRock chief medical officer Dr. Amit Rakhit. "You have a one-time procedure, and three years later patients are not just stable — many are functioning better than before. In Parkinson's, that is what success would look like." A pivotal Phase 3 trial of bemdaneprocel began enrolling patients in March in the United States, Canada, the United Kingdom and Japan, with the first interim results expected in 2028.

The BlueRock data arrive against a backdrop of accelerating progress in cell therapy for Parkinson's. Sumitomo Pharma's competing therapy, developed in partnership with Dr. Jun Takahashi at Kyoto University and using a similar dopamine-progenitor approach, won regulatory approval in Japan last year — the first cell therapy ever approved for any neurological disease. A handful of academic groups, including teams at Memorial Sloan Kettering Cancer Center and the University of Wisconsin, have additional approaches in or approaching the clinic.

Independent neurologists struck a cautious but optimistic note. "The honest answer is that twelve patients is twelve patients," said Dr. Caroline Tanner of UCSF, who chairs the Parkinson Study Group. "What is meaningful is that we now have multiple programs converging on the same idea — restore the cells, not just the chemistry — and they are showing durability we would not have predicted ten years ago." Patients enrolled in the Phase 3 study will be followed for a minimum of five years post-implantation, and BlueRock has committed to releasing yearly interim safety summaries.