Acumen Pharmaceuticals NASDAQ: ABOS said its Phase 2 ALTITUDE-AD trial of sabirnetug remains on track, with top-line results expected late in 2026, as the company continues to advance its broader Alzheimer’s disease pipeline.
On the company’s first-quarter 2026 earnings call, Chief Executive Officer Daniel O’Connell said Acumen continued to build on clinical momentum for sabirnetug, an investigational antibody designed to selectively target synaptotoxic amyloid beta oligomers rather than amyloid plaques.
“Execution has stayed on track,” O’Connell said, adding that participants have been transitioning smoothly into the 12-month open-label extension study and that the conversion rate remains high.
O’Connell described ALTITUDE-AD as a “critical proving ground” for Acumen’s thesis that targeting amyloid beta oligomers could offer a more effective and/or safer approach in Alzheimer’s disease. The study is evaluating two dose levels, 35 milligrams per kilogram and 50 milligrams per kilogram, against placebo.
ALTITUDE-AD Readout Expected Late This Year
O’Connell said the Phase 2 ALTITUDE-AD trial is designed as a “low-powered study” to detect a statistically significant difference after 18 months on its primary clinical efficacy endpoint, the amount of slowing measured by the integrated Alzheimer’s Disease Rating Scale, or iADRS.
The company also expects to report key secondary endpoints in the top-line data, including the Clinical Dementia Rating-Sum of Boxes, safety measures such as adverse event rates and amyloid-related imaging abnormality, or ARIA, rates, along with fluid and imaging biomarkers.
During the question-and-answer session, O’Connell said a “clear win” for ALTITUDE-AD would include an efficacy signal of at least 30% slowing, which he described as the upper end of the range for currently approved agents. He said Acumen will evaluate the totality of the data, including efficacy and safety, to determine how sabirnetug may be differentiated from existing therapies.
Chief Medical Officer Dr. Eric Siemers said the company will look closely at ARIA data, particularly symptomatic ARIA and serious adverse events. Siemers also noted that sabirnetug is an IgG2 antibody, while the two approved antibodies are IgG1s, which he said have more effector function and potential for more ARIA.
President and Chief Development Officer Dr. Jim Doherty said the two doses in ALTITUDE-AD were chosen to bracket the range of oligomer clearance observed in Acumen’s Phase 1 INTERCEPT-AD study. Doherty said the company will assess whether the doses show differences in efficacy or tolerability and use the results to inform future development.
Company Points to Interest From Clinicians
Asked about physician feedback, Doherty said Acumen has spoken with a number of key opinion leaders about the sabirnetug program. He said there is interest in the company’s differentiated hypothesis compared with currently approved therapies.
“Everyone’s very much looking forward to seeing the data as we release the results for the ALTITUDE trial in late 2026,” Doherty said.
Siemers said he recently attended the American Academy of Neurology meeting in Chicago, where he observed “a great deal of interest and enthusiasm” among practicing neurologists regarding information on the approved drugs lecanemab and donanemab. He said infrastructure has been a limiting factor for commercial uptake, but that it is expected to continue improving.
O’Connell said Acumen remains focused on early Alzheimer’s disease for sabirnetug in a potential future registration study. He said the company continues to have interest in preclinical Alzheimer’s disease, but that any such approach is not part of immediate plans and could be more relevant to a future enhanced brain delivery candidate.
Enhanced Brain Delivery Program Advances
Acumen also highlighted progress in its enhanced brain delivery, or EBD, program, which is being developed in collaboration with JCR Pharmaceuticals. O’Connell said the company intends to submit a notice in the second quarter of 2026 to exercise its option to license two compounds developed through the collaboration.
He said Acumen expects to discuss the candidate profiles in greater detail at a future medical meeting and continues to anticipate filing an investigational new drug application in mid-2027.
O’Connell said the EBD approach is intended to enhance Acumen’s antibodies by increasing penetration and distribution in the brain, while maintaining a favorable safety profile and allowing for patient-friendly subcutaneous dosing. He said Acumen sees differentiation because no competitor in the space has an amyloid beta oligomer-targeted therapeutic cargo.
Doherty said the company has explored multiple candidates, varying both the carrier technology from JCR and modifications on the antibody cargo side. He said Acumen has observed substantial improvements in brain exposure in rodent studies using humanized transferrin receptors and in primate studies, including improvements in the range of approximately 15-fold to 40-fold across multiple brain regions.
Cash Runway Extends Into Early 2027
Chief Financial Officer and Chief Business Officer Matt Zuga said Acumen ended March 31 with $128.4 million in cash and marketable securities. The company expects that balance to support current clinical and operational activities into early 2027.
Zuga said the increase from the prior quarter was due to a private placement completed in support of the EBD program, which grossed $35.75 million and was announced in March.
Research and development expenses were $16.5 million in the first quarter. Zuga said the year-over-year decrease was primarily due to lower manufacturing and material costs, as well as reduced contract research organization costs tied to ALTITUDE-AD, which completed enrollment in March 2025.
General and administrative expenses were $4.7 million, down primarily because of reductions in legal fees, accounting, consulting and insurance expenses. Acumen reported a loss from operations of $21.1 million and a net loss of $20.7 million for the quarter.
Zuga said the company remains focused on its Phase 2 readout later this year and advancing its EBD program as it works to build value around its portfolio of amyloid beta oligomer-targeted antibodies for Alzheimer’s patients, caregivers and stakeholders.
About Acumen Pharmaceuticals NASDAQ: ABOS
Acumen Pharmaceuticals, Inc is a clinical-stage biopharmaceutical company focused on the discovery and development of oral small molecule therapies for neurodegenerative diseases. Leveraging a proprietary drug discovery platform that integrates chemoproteomics, high-throughput screening and computational chemistry, the company seeks to identify and optimize compounds that selectively modulate pathological protein aggregation. Its approach is designed to address the underlying biology of conditions such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and related proteinopathies.
The company's pipeline comprises multiple lead candidates at various stages of preclinical and early clinical development.
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