Acumen Pharmaceuticals, Inc. (NASDAQ: ABOS) announced on October 30, 2026, that its Phase 2 ALTITUDE-AD clinical trial for sabirnetug (ACU193) did not meet its primary endpoint. The trial evaluated the drug in participants with early Alzheimer’s disease and failed to show a statistically significant difference in cognitive and functional decline compared to placebo at either the 35 mg/kg or 50 mg/kg dose.
The primary endpoint measured change from baseline in the Integrated Alzheimer’s Disease Rating Scale (iADRS) at 18 months. Additionally, the trial did not achieve statistical significance on key secondary efficacy endpoints, including the Clinical Dementia Rating – Sum of Boxes (CDR-SB).
Sabirnetug was generally well tolerated during the trial. However, amyloid-related imaging abnormalities - edema (ARIA-E) was observed in approximately 10% of sabirnetug-treated participants. Despite the lack of efficacy results, an analysis of amyloid plaque load, measured by positron emission tomography (PET) SUVr, demonstrated statistically significant reduction in amyloid plaques for both dose levels at week 36 and week 76.
Based on these initial topline results, Acumen plans to cease clinical development of sabirnetug, including the open-label extension portion of the ALTITUDE-AD trial. The company stated it expects to receive additional data in the coming weeks, including fluid biomarker and imaging data, but does not anticipate these results will change the efficacy conclusions. Acumen intends to evaluate strategic options for its Enhanced Brain Delivery (EBD) program and implement cash conservation measures.
