Kyoto iPSC dopamine-cell trial

The research record

This is the project's file for this landmark, as written and checked. Sources are listed at the end; anything not yet confirmed is marked "Not yet verified".

Who

Nobukatsu Sawamoto and Ryosuke Takahashi (Kyoto University Hospital) with Jun Takahashi, Daisuke Doi and colleagues (CiRA, Kyoto's iPS cell centre). Cells for the last four patients were made by Sumitomo Pharma. Published in Nature, 16 April 2025 online (2025;641:971–977). Registered as jRCT2090220384 (a Japanese registry).

What happened

Investigator-initiated, open-label, single-centre trial. Patients aged 50 to 69 were recruited between August 2018 and January 2019. Cells came from an iPSC line made from the blood of a healthy donor whose immune-type genes (HLA haplotype) match about 17% of Japanese people, which lowers the chance of rejection. The cells were sorted for a dopamine-progenitor marker (CORIN). Three patients got a low dose (2.1 to 2.6 million cells per side) and four a high dose (5.3 to 5.5 million). The first patient had the two sides operated eight months apart as a safety check, and was assessed for safety only; the other six had both sides done at once and make up the efficacy group. (A further patient registered earlier was excluded before surgery after COVID-19 infection.) All took the immune suppressant tacrolimus, halved at 12 months and stopped at 15.

Results at 24 months: no serious adverse events and 73 mild to moderate events; MRI showed no graft overgrowth. Of six patients assessed for efficacy, four improved on the motor exam off medication (average 9.5 points, 20.4%) and five on medication (average 4.3 points, 35.7%). Hoehn-Yahr stage improved in four. Putamen F-DOPA uptake rose 44.7%, more in the high-dose group. Dyskinesia (involuntary movement) increased in some when drug doses were not cut.

Why it moved us toward a cure

It is a published human test of iPSC-derived dopamine cells from a donor, following the monkey work in landmark 30 and relying on cell reprogramming (landmark 32). A second route beside embryonic cells (landmark 10).

Outcome

Advanced. Sumitomo Pharma applied on 5 August 2025. On 19 February 2026 the health ministry's regenerative-medicine committee found the product approvable under conditional, time-limited approval, with a 7-year duration. Conditions: surveillance of all treated patients, and training so that only experienced centres use it. The approval of Amchepry (raguneprocel) on 6 March 2026 is confirmed by Sumitomo Pharma's release and has its own file, landmark 356. Caveats: seven people, no control group, and mixed manufacturing sites.

Sources

• Sawamoto et al., Nature 2025, DOI 10.1038/s41586-025-08700-0; Europe PMC full text
• CiRA release, 17 Apr 2025
• Ministry/PMDA deliberation report, 19 Feb 2026 (English translation): application date, committee finding, conditions, 7-year duration
• Sumitomo Pharma release, 6 March 2026
• PMLiVE on the approval; Parkinson's Canada
• Not yet verified: the ministry's own approval notice (the ministry notice itself was not reached; the 6 March date is from Sumitomo Pharma's release, the PMDA document gives the 19 Feb committee date); post-24-month outcomes; the post-marketing study's design (Sumitomo's 15 July 2026 release says it is under way).