ProMIS Neurosciences Reports Positive 6‑Month Interim Data for PMN310 (Phase 1b)

What Happened
ProMIS Neurosciences (filed 8‑K on July 28, 2026) announced blinded six‑month interim results from the PRECISE‑AD Phase 1b trial of PMN310 in early Alzheimer’s disease. The company reported a favorable safety profile across genotypes and early, directionally consistent biomarker changes in a pooled, blinded analysis of 136 patients. A virtual webinar with key opinion leaders Dr. Will Mantyh and Dr. Michael Weiner was held July 28, 2026, and presentation slides are available on the company website.

Key Details

• Interim population: 136 AD patients in a blinded 3:1 active‑to‑placebo randomization.
• Safety: No ARIA‑E cases reported; total ARIA rate 4.4% (all mild, asymptomatic ARIA‑H); no drug‑related serious adverse events or discontinuations at interim.
• High‑risk subgroup: 61% of patients were APOE4 carriers (11% homozygotes); no ARIA‑E observed in any genotype.
• Biomarkers (blinded): 68.5% of patients showed a decline (change ≤ 0) in plasma pTau217; 62.5% showed a decline in CSF MTBR‑tau243.
• Next milestone: Trial remains blinded; unblinded 12‑month topline results, including efficacy data, expected in Q1 2027.

Why It Matters
For investors, these interim findings highlight a potentially differentiated safety profile (no ARIA‑E and low, mild ARIA‑H rate) and early biomarker signals consistent with target engagement for PMN310, a drug designed to selectively bind toxic Aβ oligomers. The data are blinded and not a determination of efficacy; the materially important next step is the unblinded 12‑month topline readout expected in Q1 2027. The company’s disclosure also includes standard forward‑looking statement cautions.