Acumen Pharmaceuticals halts sabirnetug development after Phase 2 Alzheimer's trial fails on all key measures

Acumen Pharmaceuticals announced on October 30 that its Phase 2 ALTITUDE-AD clinical trial of sabirnetug (ACU193) failed to meet its primary endpoint, sending shares of ABOS down roughly 79% in premarket trading. The trial measured change from baseline in cognitive and functional decline using the Integrated Alzheimer's Disease Rating Scale at 18 months, and neither the 35 mg/kg nor the 50 mg/kg intravenous dose showed a statistically significant benefit over placebo.

The drug also failed to achieve statistical significance on key secondary efficacy endpoints, including the Clinical Dementia Rating Sum of Boxes, with no meaningful difference observed between either sabirnetug treatment arm and the placebo arm. ALTITUDE-AD was a randomized, double-blind, placebo-controlled trial that enrolled 542 participants with mild cognitive impairment or mild dementia due to early Alzheimer's disease across sites in the United States, Canada, the European Union and the United Kingdom.

Sabirnetug was generally well tolerated, with amyloid-related imaging abnormalities involving edema observed in approximately 10% of sabirnetug-treated participants. Based on the topline results, Acumen said it will cease all development of sabirnetug, including the open-label extension portion of the trial, and will evaluate strategic options including its Enhanced Brain Delivery program developed in partnership with JCR Pharmaceuticals.