Phase I/II trial of iPS-cell-derived dopaminergic cells for Parkinson’s disease, 2025, Sawamoto et al

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Phase I/II trial of iPS-cell-derived dopaminergic cells for Parkinson’s disease

Sawamoto, Nobukatsu; Doi, Daisuke; Nakanishi, Etsuro; Sawamura, Masanori; Kikuchi, Takayuki; Yamakado, Hodaka; Taruno, Yosuke; Shima, Atsushi; Fushimi, Yasutaka; Okada, Tomohisa; Kikuchi, Tetsuhiro; Morizane, Asuka; Hiramatsu, Satoe; Anazawa, Takayuki; Shindo, Takero; Ueno, Kentaro; Morita, Satoshi; Arakawa, Yoshiki; Nakamoto, Yuji; Miyamoto, Susumu; Takahashi, Ryosuke; Takahashi, Jun

Abstract
Parkinson’s disease is caused by the loss of dopamine neurons, causing motor symptoms. Initial cell therapies using fetal tissues showed promise but had complications and ethical concerns1,2,3,4,5. Pluripotent stem (PS) cells emerged as a promising alternative for developing safe and effective treatments6.

In this phase I/II trial at Kyoto University Hospital, seven patients (ages 50–69) received bilateral transplantation of dopaminergic progenitors derived from induced PS (iPS) cells. Primary outcomes focused on safety and adverse events, while secondary outcomes assessed motor symptom changes and dopamine production for 24 months.

There were no serious adverse events, with 73 mild to moderate events. Patients’ anti-parkinsonian medication doses were maintained unless therapeutic adjustments were required, resulting in increased dyskinesia. Magnetic resonance imaging showed no graft overgrowth.

Among six patients subjected to efficacy evaluation, four showed improvements in the Movement Disorder Society Unified Parkinson’s Disease Rating Scale part III OFF score, and five showed improvements in the ON scores. The average changes of all six patients were 9.5 (20.4%) and 4.3 points (35.7%) for the OFF and ON scores, respectively. Hoehn–Yahr stages improved in four patients.

Fluorine-18-l-dihydroxyphenylalanine (18F-DOPA) influx rate constant (Ki) values in the putamen increased by 44.7%, with higher increases in the high-dose group. Other measures showed minimal changes.

This trial (jRCT2090220384) demonstrated that allogeneic iPS-cell-derived dopaminergic progenitors survived, produced dopamine and did not form tumours, therefore suggesting safety and potential clinical benefits for Parkinson’s disease.

Web | DOI | PMC | PDF | Nature
 
Nature News: "First-of-a-kind stem-cell therapies set for approval in Japan"

23 February 2026

Japan’s health ministry has endorsed issuing conditional approval for two first-of-a-kind medicines.

Amchepry, made by Sumitomo Pharma and Racthera, both in Tokyo, for the treatment of Parkinson’s disease, has been tested in seven people. ReHeart, made by Cuorips in Tokyo for severe heart failure, has been tested in eight people. But bigger trials are needed to ensure that these drugs are safe and effective, Knoepfler says.

The treatment involves collecting blood cells from volunteers, reprogramming them into iPS cells and then coaxing the reprogrammed cells into becoming dopamine-making progenitor cells. Neurosurgeons then tested the technique by transplanting these cells into the brains of people with Parkinson’s disease.

For Hiroshi Kawaguchi, an orthopaedic surgeon at Nadogaya Hospital in Chiba, Japan, the clinical data for both drugs are “very weak”. Neither trial was big enough to assess the risks of these therapies, he says. The trials also lacked control groups, precluding firm conclusions about how much benefit they provide — if any.



MedicalXpress: "Japan approves stem-cell treatment for Parkinson's in world first"

6 March 2026

Japan has approved ground-breaking stem-cell treatments for Parkinson's and severe heart failure, one of the manufacturers and media reports said Friday, with the therapies expected to reach patients within months.
 
Interesting news. Seems pretty wild that they’ve approved it after only testing safety not efficacy. I know levodopa is the main PD ‘treatment’ and it seems dopamine producing neurons do decay, but there’s a lot of questions still on what the mechanisms of PD are AFAIK. Maybe we’ll find more from usage rather than from studies. Can imagine there being plenty desperate enough to try.
 
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