ProMIS Neurosciences reports positive six-month interim results from a Phase Ib trial of its antibody therapy targeting toxic amyloid‑beta oligomers in patients with early stage Alzheimer’s disease.
Notably the U.S.-Canadian company has seen no cases of amyloid-related imaging abnormalities (ARIA)-E so far, the more serious edema subtype of amyloid‑related imaging abnormalities seen in around 12–25% of those treated with the two approved antibody therapies for the condition, lecanemab and donanemab. Total ARIA incidence was 4.4% in the trial to date, and all of these events were classified as mild and asymptomatic.
Importantly, this safety profile held even in a genetically high‑risk group. Around 61% of the 136 trial participants carries at least one copy of the Alzheimer’s disease genetic risk variant APOE4 and 11% have two copies of this allele. People who carry APOE4 are at higher risk of developing ARIA and are often excluded from treatment with lecanemab and donanemab because of this, especially if they are APOE4 homozygotes.
“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, in a press statement.
The PRECISE‑AD trial is due to continue for another six months with intravenous infusions continuing once every 28 days, as for the first six months. The treatment delivery method used in the trial is similar to that of lecanemab and donanemab. The timing is also similar with lecanemab typically given every two weeks for around 18 months and donanemab every four weeks for the same time period.
ProMIS’s interim analysis was not designed to read out true efficacy data, but the researchers did look at two tau-related disease biomarkers—Plasma pTau217 and CSF MTBR‑tau243—and found levels had declined in 68.5% and 62.5% of participants, respectively, over six months.
Early downward movement in both markers helps ProMIS to argue that PMN310 is biologically active in the expected direction, but the 12 month readout data will give more concrete answers about the efficacy of PMN310.
“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, in a press statement.
“The absence of ARIA-E, an overall favorable safety profile, and early biomarker movement together align with our expectations based on our prior studies,” commented Warma.
The FDA granted Fast Track status for PMN310 for the treatment of Alzheimer’s disease in July 2025, which means it is eligible for priority review and possible accelerated approval if later trial results support this.
The Phase Ib trial has now completed enrollment and is in its later stages, with 12‑month primary completion expected towards the end of this year and a data readout in the first quarter of 2027.
