Acumen Pharmaceuticals, Inc. (NASDAQ: ABOS), a clinical-stage biopharmaceutical company based in Newton, Massachusetts, on Friday said that initial topline results from its Phase 2 ALTITUDE-AD trial showed sabirnetug (ACU193) failed to meet the primary endpoint of slowing cognitive and functional decline versus placebo after 18 months at either the 35 mg/kg or 50 mg/kg dose.

The trial also did not achieve statistical significance on key secondary efficacy endpoints, including the Clinical Dementia Rating – Sum of Boxes, and showed no meaningful difference between either treatment arm and placebo.

Sabirnetug was generally well tolerated, with amyloid-related imaging abnormalities with oedema observed in about 10% of treated participants. Analyses showed statistically significant reductions in amyloid plaque load at both dose levels at weeks 36 and 76.

Acumen expects to analyse additional biomarker and imaging data in the coming weeks but does not expect those results to alter the trial's efficacy conclusions.

Following the outcome, the company plans to discontinue development of sabirnetug, including the open-label extension of ALTITUDE-AD, while evaluating strategic options, including its Enhanced Brain Delivery programme.

ALTITUDE-AD, launched in 2024, enrolled 542 patients with early Alzheimer's disease across sites in the United States, Canada, the European Union and the United Kingdom.