In the blinded interim analysis evaluating 136 AD patients, PMN310 was observed to have a favorable safety profile across all genotypes, with no cases of amyloid-related imaging abnormalities-edema (ARIA-E) reported as of the data cutoff date, and early, directionally consistent movement in disease-relevant biomarkers potentially reflective of the randomization pattern. The trial remains blinded and ongoing with topline 12-month results expected in the first quarter of 2027.

Interim Highlights

Favorable safety profile across all genotypes: No ARIA-E and 4.4% total ARIA (all mild and asymptomatic, consisting of only amyloid-related imaging abnormalities-microhemorrhages (ARIA-H)), with no treatment-related serious adverse events and no drug-related discontinuations at the interim.

 

Same profile in high-risk APOE4 carriers: No ARIA-E observed in any genotype in a population that included 61% APOE4 carriers, of which 11% were homozygotes, a group underserved by approved amyloid-directed therapies.

 

Early biomarker movement consistent with target engagement: On a blinded basis, a majority of patients showed reductions in disease-relevant biomarkers against expected increases in natural-history trajectories: 68.5% of patients had a decline from baseline (change ≤ 0) in plasma pTau217 and 62.5% had a decline in CSF MTBR-tau243, consistent with a potential beneficial drug effect and potentially reflective of the trial’s 3:1 active-to-placebo randomization. These are blinded interim biomarker observations, meaning treatment allocations between drug and placebo groups are not known at this time. These observed biomarker trends are not a determination of efficacy, and trends in biomarkers may not ultimately be reflective of clinical effects.

 

Differentiated, oligomer-selective mechanism: PMN310 is designed to selectively bind toxic amyloid-beta oligomers while avoiding plaque, a mechanism intended to decouple potential efficacy from ARIA risk.

 

Clear path forward: Unblinded 12-month topline data expected Q1 2027, including efficacy data.
"These interim data reinforce our central thesis: by selectively targeting toxic oligomers, PMN310 has the potential to deliver the benefits of amyloid-directed therapy without the ARIA burden that has constrained this class of drugs," said Neil Warma, Chief Executive Officer of ProMIS Neurosciences. "The absence of ARIA-E, an overall favorable safety profile, and early biomarker movement together align with our expectations based on our prior studies. We look forward to our 12-month topline readout in the first quarter of 2027."

 

Dr. Will Mantyh, a behavioral neurologist at the University of Minnesota, said, "In real-world practice, ARIA risk is the central prescribing barrier: clinicians, patients, and health systems must contend with the issues of safety monitoring, identification, and sometimes emergent neurological treatment of ARIA. A profile with low incidence of total ARIA, including no ARIA-E, would be a game-changer. Just as importantly, 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."

 

ProMIS will host a live webinar today to discuss these results.