ProMIS Reports Blinded Six‑Month Interim Data Showing No ARIA‑E in PMN310 Phase 1b Trial

If confirmed at the planned unblinded 12‑month readout in Q1 2027, the blinded trends could indicate PMN310 engages Alzheimer’s biology without causing ARIA‑E, a key safety barrier for plaque‑binding antibodies.

Overview

ProMIS announced positive blinded six‑month safety and biomarker observations from PRECISE‑AD, a Phase 1b study of PMN310 in early Alzheimer’s patients, and the trial remains blinded and ongoing.
The interim safety readout reported no cases of ARIA‑E (brain swelling) across genotypes and a 4.4% rate of mild, asymptomatic ARIA‑H (microhemorrhages).
On a blinded basis, a majority of participants showed declines in two disease biomarkers with 68.5% falling in plasma pTau217 and 62.5% falling in CSF MTBR‑tau243, which the company says may reflect target engagement.
PRECISE‑AD enrolled 144 participants in three ascending IV dose cohorts with 3:1 active:placebo randomization and expects an unblinded 12‑month topline readout in Q1 2027.
PMN310 is engineered to bind toxic amyloid‑beta oligomers but avoid plaques and vascular deposits; if later unblinded results confirm safety and biomarker effects, the drug could reduce the monitoring and exclusion burdens that limit current plaque‑binding therapies.