ProMIS Neurosciences Stock Surges on Positive Alzheimer's Drug Safety Data

Shares of ProMIS Neurosciences Inc. (NASDAQ:PMN) surged 13% on Tuesday after the biopharmaceutical company announced positive interim safety data from its Phase 1b trial for PMN310, an experimental treatment for Alzheimer’s disease. The blinded six-month analysis showed the drug candidate avoided a key safety concern that has affected other treatments in its class.

Key Safety Findings

The most significant finding from the PRECISE-AD trial was the absence of amyloid-related imaging abnormalities with edema (ARIA-E), a form of brain swelling that is a serious side effect associated with other amyloid-targeting therapies. According to the company's announcement, this held true across all patient genotypes, including high-risk APOE4 homozygotes.

The interim analysis of 136 patients reported:

• 0% incidence of ARIA-E.
• A total ARIA rate of 4.4%, consisting only of mild and asymptomatic microhemorrhages (ARIA-H).
• No treatment-related serious adverse events or drug-related discontinuations.

These safety results are particularly notable given that the study population included 61% APOE4 carriers, a group genetically predisposed to a higher risk of developing ARIA side effects from amyloid-plaque-clearing drugs.

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Biomarker Data and Drug Mechanism

While the trial remains blinded and the data is not a formal determination of efficacy, ProMIS reported encouraging biomarker trends. On a blinded basis, 68.5% of patients showed a decline in plasma pTau217 and 62.5% had a decline in CSF MTBR-tau243, two key indicators of Alzheimer's pathology. The company noted this was consistent with the trial's 3:1 active-to-placebo randomization.

PMN310 is designed to selectively target toxic amyloid-beta oligomers while avoiding amyloid plaque. This mechanism is intended to provide the therapeutic benefits of amyloid-directed therapy while minimizing the ARIA risk associated with plaque removal. "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, CEO of ProMIS Neurosciences.

Outlook for Investors

The positive safety profile is a crucial de-risking event for PMN310, potentially differentiating it in a competitive landscape for Alzheimer's treatments. The trial is ongoing, and investors will be looking toward the release of topline 12-month results, which the company expects in the first quarter of 2027.