ProMIS Neurosciences reported six‑month interim results from its Phase Ib trial of the antibody PMN310, which targets toxic amyloid‑beta oligomers in early‑stage Alzheimer’s disease.
Safety findings show low ARIA rates
The trial enrolled 136 participants, about 61 % of whom carry at least one APOE4 allele and 11 % are homozygous. No cases of ARIA‑E, the edema subtype that has appeared in roughly 12‑25 % of patients treated with lecanemab or donanemab, have been observed so far. Overall, 4.4 % of participants experienced any ARIA, all classified as mild and asymptomatic.
These safety outcomes held even in the genetically high‑risk subgroup, a point the company highlighted given that many existing antibodies exclude APOE4 carriers, especially homozygotes, from treatment.
Biomarker shifts suggest biological activity
While the interim analysis was not intended to assess efficacy, researchers measured two tau‑related biomarkers. Plasma pTau217 levels fell in 68.5 % of participants, and CSF MTBR‑tau243 declined in 62.5 % over the six‑month period.
“Plasma pTau217 and CSF MTBR‑tau243 are among the most informative fluid biomarkers we have for tracking Alzheimer’s biology; seeing early, coherent movement in both is highly encouraging before a definitive readout,” said Will Mantyh, MD, a behavioral neurologist at the University of Minnesota.
Primary completion is expected later this year, with a full data readout slated for the first quarter of 2027.
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Given the favorable safety profile and early biomarker trends, the company believes PMN310 may offer the intended benefits of amyloid‑directed therapy while avoiding the ARIA burden that has limited other antibodies. If later results confirm efficacy, the Fast Track designation granted by the FDA in July 2025 could enable priority review and a faster path to market.
The trial, formally known as PRECISE‑AD, has completed enrollment and is now in its later stages, with primary completion expected towards the end of this year.
CEO Neil Warma emphasized that the absence of ARIA‑E aligns with the company’s central thesis: selective targeting of toxic oligomers should preserve the therapeutic advantages of amyloid reduction while minimizing vascular side effects that have constrained broader use of antibodies in clinical practice.
In the press statement, Warma also noted that the interim safety and biomarker data reinforce confidence in the underlying mechanism, suggesting that the antibody’s ability to clear oligomeric species may translate into measurable disease modification once longer‑term efficacy endpoints are examined.
The Fast Track status awarded by the FDA not only reflects regulatory recognition of the unmet need in Alzheimer’s disease but also provides a pathway for accelerated development milestones, including potential eligibility for priority review should the 12‑month efficacy data meet prespecified criteria.
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