ProMIS Neurosciences has reported the first human evidence that its investigational Alzheimer’s therapy PMN310 reduced amyloid-beta oligomers in cerebrospinal fluid, providing early evidence that the antibody reached and engaged its intended biological target.

The findings were presented at the 2026 Alzheimer’s Association International Conference (AAIC) and are based on samples collected during the company’s Phase 1a trial in healthy volunteers. According to the company, participants who received PMN310 showed a dose-dependent reduction in detectable amyloid-beta oligomers three and 29 days after a single dose.

Amyloid-beta oligomers are widely considered to be among the most toxic forms of amyloid involved in Alzheimer’s disease and are increasingly being investigated as therapeutic targets. Unlike antibodies that bind to amyloid plaques, PMN310 has been designed to selectively target soluble oligomers while avoiding plaque deposits and vascular amyloid.

Neil Warma, chief executive officer of ProMIS Neurosciences, said: “Using CSF samples from our Phase 1a study, subjects receiving PMN310 showed a clear dose-dependent reduction in oligomer particles, which, we believe, represents direct evidence that PMN310 was able to reach the brain and engage its intended target.”

The company said the findings represent one of the first quantitative demonstrations of treatment-related reductions in amyloid-beta oligomers in humans.

PMN310 was also generally well tolerated in the Phase 1a study. Cerebrospinal fluid drug concentrations increased in a dose-dependent manner, with the antibody demonstrating a cerebrospinal fluid half-life of approximately 27 days. The presentation also included preclinical data showing preservation of memory and learning in a mouse model of Alzheimer’s disease.

ProMIS is currently evaluating PMN310 in the PRECISE-AD Phase 1b trial, which has enrolled 144 patients with mild cognitive impairment due to Alzheimer’s disease or mild Alzheimer’s disease. The randomised, double-blind, placebo-controlled study is evaluating the safety, tolerability and pharmacokinetics of multiple ascending doses over a 12-month treatment period.

Johanne Kaplan, chief development officer at ProMIS Neurosciences, said: “We believe the data presented today provide pharmacodynamic evidence supportive of PMN310’s differentiated mechanism of action.”

The company also confirmed that it expects to report blinded six-month interim data from the PRECISE-AD study in the coming weeks. The interim analysis will focus on aggregate safety findings and biomarker trends, while topline unblinded results are expected during the first quarter of 2027.

Although the current findings do not demonstrate clinical benefit in patients with Alzheimer’s disease, they provide early evidence that PMN310 is engaging its intended target in humans, an important step in the development of therapies designed to address one of the underlying drivers of neurodegeneration.