Bosutinib

The trials are run by doctors, not a company: Professor Haruhisa Inoue's team at Kyoto University's Center for iPS Cell Research and Application (CiRA), with Japanese government research funding. Pfizer Japan, which sells bosutinib for leukaemia, supplied the drug and advice for Phase 2. For Phase 3, Japanese trade press reports that generic maker Towa Pharmaceutical will supply the study drug.

In nerve cells made from ALS patients' stem cells, two enzymes called Src and c-Abl are overactive. This blocks autophagy, the cell's system for clearing out damaged proteins, so misfolded proteins build up and the cells die. Bosutinib blocks these enzymes, and in lab and mouse tests it helped nerve cells survive.

A small Phase 1 study ran from 2019 to 2021. The Phase 2 trial started in 2022 at 7 Japanese hospitals and is listed as completed in July 2024. Preliminary results were announced in June 2024, but we could not find a full peer-reviewed report. In October 2026 Japanese trade press reported that an investigator-initiated Phase 3 trial should begin in Japan in 2027.

All 26 participants took bosutinib (13 at 200 mg, 13 at 300 mg) for 24 weeks; there was no placebo group. Their ALS functional score (ALSFRS-R) fell significantly less than in the placebo group of an earlier edaravone trial, which met both main goals the researchers had set in advance. But the lead researcher said they could not show a clear advantage over the edaravone-treated group of that trial, results varied a lot between people, and one of two secondary goals was missed. Comparisons with other trials' patients are much weaker evidence than a placebo group, and the full Phase 2 results have not been published in a journal.

This is the most favourable result reported. See all key studies for the full picture.

Phase 2 included people whose ALS began within the previous 2 years and who lost 1 to 4 points on the ALSFRS-R during a 12-week observation period. The researchers saw hints that people with lower neurofilament light (NfL, a blood marker of nerve damage) did better. Side effects included diarrhoea and liver problems, which sometimes needed dose changes or extra treatment.

Japanese pharmaceutical trade press reported on 1 October 2026 that the doctor-led Phase 3 is expected to start in Japan in 2027, with Towa Pharmaceutical supplying the drug. No trial has been registered yet, and design details have not been published.

No bosutinib trial for ALS is enrolling now. Bosutinib is approved for leukaemia, but it is not approved for ALS and has real side effects, so it should not be used for ALS outside a trial.

• iDReAM Phase 1 and Phase 2 (NCT04744532) completed · Japan