Amylyx Ends AMX0035 Development in Progressive Supranuclear Palsy After Phase IIb Failure

Amylyx Pharmaceuticals has discontinued development of its experimental therapy AMX0035 in progressive supranuclear palsy (PSP) after the drug failed in the Phase IIb ORION trial (NCT06122662). The oral combination of sodium phenylbutyrate and taurursodiol showed no difference versus placebo at 24 weeks on the PSP Rating Scale, prompting the cancellation of both the Phase IIb and planned Phase III stages.

PSP is a rare neurodegenerative disorder within the atypical parkinsonism spectrum, causing balance, vision, and speech difficulties. Despite the setback, Amylyx will continue developing AMX0035 in Wolfram syndrome, a rare genetic disease.

Previously, AMX0035 was marketed as Relyvrio/Albrioza for ALS following conditional approvals in North America, but was withdrawn in 2024 after Phase III data failed to confirm efficacy. Unlike that episode, Amylyx has not announced layoffs following ORION’s discontinuation and maintains a cash runway through 2026, with focus shifting to its Phase III avexitide trial in PBH.

29-08-2025