Bayer starts pivotal Parkinson's cell therapy trial

Bayer's much-anticipated stem cell therapy for Parkinson's disease is gathering momentum, with dosing in phase 3 trials now underway.

The first patient has already been treated with bemdaneprocel, a one-shot treatment designed to replace the dopamine-producing neurons that degenerate in Parkinson's, which is being developed by Bayer's BlueRock Therapeutics subsidiary.

Meanwhile, Bayer is also making progress with a gene therapy for Parkinson's developed by its AskBio unit, with the first European patients now entering a phase 2 trial of the AB-1005 candidate. The therapy delivers a gene into the putamen region of the brain that expresses a growth factor called GDNF, which is thought to promote the survival of dopaminergic neurons.

According to Bayer, the exPDite-2 study of bemdaneprocel is the first phase 3, pivotal study to test an allogeneic pluripotent stem cell-derived therapy in Parkinson's patients. Other groups are looking at cell therapy approaches to the disease, including two academic groups – in Japan and the US/Canada – that published encouraging initial data from human tests in the journal Nature earlier this year.

Other companies working in this area include Aspen Neurosciences, Sumitomo Pharma, TreeFrog Therapeutics, and Cellino. Initial cell therapies using foetal tissues showed promise, but had complications and ethical concerns, so most developers are now focusing on using induced pluripotent stem (iPS) or isolated human embryonic stem (hES) cells.

Bayer's move into phase 3 follows positive 24-month data from the phase 1 exPDite study in 12 patients, which backed up the safety and tolerability of the therapy and showed that the transplanted cells were surviving and growing in the brain. Moreover, there were trends towards improvements in measures of motor function two years after the surgery to implant the stem cells.

exPDite-2 has a target enrolment of 102 patients with moderate Parkinson's symptoms, measuring the change from baseline to week 78 in Hauser PD Diary measure of 'on' time without dyskinesia – i.e., the period where muscle symptoms associated with Parkinson's are controlled without involuntary, uncontrolled movements – adjusted for a 16-hour waking day.

"The initiation of the expDite-2 phase 3 trial marks a significant milestone in our commitment to transform the treatment landscape for Parkinson's disease through innovative therapies," said Christian Rommel, head of pharma R&D at Bayer.

"Our dual approach […] through both cell and gene therapies exemplifies our strategic vision and maximises our chances of offering renewed hope for Parkinson's patients who have been waiting for new therapies for too long."

Bayer has set up a $250 million manufacturing facility in Berkeley, California, to supply bemdaneprocel for the exPDite-2 trial and support its cell therapy aspirations.

It is estimated that more than 10 million worldwide are living with Parkinson's, making it the world's second most prevalent neurodegenerative disease and the most frequent movement disorder. At present, there is no cure, and current treatment options cannot wholly control symptoms.