Japan grants conditional approval to Amchepry cell therapy for Parkinson’s
Approval follows early trial showing dopamine-producing cells survive
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- Japan conditionally approved Amchepry, a stem cell therapy for Parkinson's disease.
- It is designed for patients unresponsive to levodopa and aims to replace dopamine-producing brain cells.
- Early trials showed increased dopamine levels and motor improvements with mostly mild side effects.
Japan’s Ministry of Health, Labour and Welfare has granted conditional approval to Amchepry, Sumitomo Pharma’s stem cell-derived therapy designed to replace dopamine-producing nerve cells, for people with Parkinson’s disease who do not respond adequately to existing treatments such as levodopa.
The approval was based on results from a Phase 1/2 study (jRCT2090220384), which showed that transplanted dopaminergic progenitor cells survived and produced dopamine in the brain — findings that suggest the therapy may be safe and could provide clinical benefit for people with Parkinson’s disease.
After the therapy receives a National Health Insurance price listing, Sumitomo Pharma will begin marketing the treatment in Japan, according to a company press release.
Post-marketing study planned to support full approval
The company will conduct a post-marketing clinical study and ongoing safety monitoring to seek full approval for the therapy within the designated period. The treatment is also being tested in a Phase 1/2 trial (NCT06482268) at the University of California, San Diego, which is expected to be completed in 2028. The study is evaluating the therapy’s safety and efficacy in seven people with Parkinson’s disease ages 40 to 75.
Parkinson’s disease is caused by the progressive loss of dopaminergic neurons — the nerve cells that produce dopamine, a signaling chemical that helps control movement. As these neurons die, people develop motor symptoms such as tremors, muscle stiffness, and slowed movements, as well as a range of nonmotor symptoms.
The most widely used treatment, levodopa (L-DOPA), works by boosting dopamine levels, helping ease symptoms. However, it does not stop or reverse the underlying loss of nerve cells. Over time, long-term use may lead to complications such as off episodes — when the medication’s effects wear off before the next dose — or dyskinesia, involuntary movements that occur when the medication is active.
Amchepry is an off-the-shelf cell therapy made from induced pluripotent stem cells (iPSCs) obtained from healthy donors. iPSCs are created by reprogramming adult cells, typically from the skin or blood, into a stem cell state that can be guided to develop into many different cell types, including dopamine-producing neurons.
For this therapy, the iPSCs are guided to develop into dopaminergic neuron progenitor cells. These cells are surgically implanted into the striatum, a brain region involved in movement, where they can mature into dopamine-producing neurons. The goal is to replace lost nerve cells and help restore dopamine signaling.
Early trial suggests stem cell therapy is safe and may help symptoms
The investigator-initiated Phase 1/2 trial, conducted at Kyoto University Hospital, enrolled seven patients ages 50 to 69 who received either a low or high dose of Amchepry.
The study reported 73 adverse events in total — 72 mild and one moderate case of dyskinesia. The most common issue was itching at the procedure site. No serious adverse events requiring hospitalization or resulting in death were reported, and imaging showed no signs of tumor-like cell growth.
Brain imaging showed a 44.7% increase in dopamine levels in the striatum, the brain region that controls movement. The effect appeared dose-dependent: dopamine levels rose by about 7% in the low-dose group and 63.5% in the high-dose group.
Efficacy data from six patients evaluated two years after transplantation showed meaningful improvements in motor function. During off periods, when medication effects wear off, patients had an average 20.4% reduction in MDS Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Part III motor scores. During on periods, when symptoms are better controlled with medication, motor scores improved by 35.7%.
Four patients also showed reduced disease severity during off periods, based on improvements in their Hoehn–Yahr stage.
Results also suggested that a relatively mild immunosuppressant regimen was sufficient to prevent rejection in the study participants.
The treatment has received the SAKIGAKE designation in Japan, a program designed to accelerate development and approval of innovative regenerative medical products for serious diseases. It was also granted orphan regenerative medical product status, which supports treatments intended for fewer than 50,000 patients in Japan with high unmet medical need.
