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Otsuka, Ionis’ experimental ALS drug meets main goal in late-stage study

By Thomson Reuters Sep 22, 2026 | 7:37 AM

Sept 22 (Reuters) – Otsuka Pharmaceutical and Ionis Pharmaceuticals said on Tuesday their experimental drug met the main goal of ​a late-stage study in patients with ‌a rare inherited form of amyotrophic lateral sclerosis, or ALS.

Here are more details:

• Otsuka’s ulefnersen improved function and survival compared with placebo in patients with ‌FUS-ALS, ​a rare inherited form ⁠of the disease that ⁠damages nerve cells controlling movement.

• There are currently no approved treatments specifically targeting the genetic cause of FUS-ALS.

• The drug ​also reduced markers linked to nerve cell damage and delayed disease progression.

• Most ⁠side effects were mild ⁠or moderate, and the companies said ​the drug showed a favorable safety profile.

• Otsuka ​and Ionis plan to discuss the ‌results with the US FDA and other health authorities globally as they pursue potential accelerated approval pathways.

• FUS-ALS causes progressive muscle ⁠weakness that can leave patients unable to move, speak, swallow or breathe independently.

• Otsuka’s ulefnersen is an ⁠experimental medicine ‌designed to reduce production of ⁠the FUS protein linked to ​the ‌disease.

• Separately, Otsuka launched a global ​early access ⁠program for eligible FUS-ALS patients who cannot participate in clinical trials, allowing physicians to request access to ulefnersen before any potential approval.

(Reporting by Sahil Pandey in Bengaluru; Editing by ​Leroy Leo)