New Study Suggests Alzheimer’s Drug Lecanemab May Be Less Effective in Women”

A recent study has raised questions about the effectiveness of lecanemab, an FDA-approved Alzheimer’s drug, in female patients. While the drug has shown promise in slowing cognitive decline by 27% overall, data from its Phase 3 clinical trial indicated that women may experience little to no benefit. Researchers from McGill University conducted simulated trials to further investigate this disparity, shedding light on potential sex differences in drug efficacy. The study was published in the Journal of Alzheimer’s & Dementia on Jan. 29, 2025

Lecanemab, marketed as Leqembi, became the second Alzheimer ’s-modifying drug to gain FDA approval in 2023. Despite its overall success in slowing cognitive decline, a subset of data from the Phase 3 trial suggested that the drug’s effectiveness might vary by sex. While the FDA committee unanimously confirmed the drug’s clinical benefits, the observed sex difference has sparked debate among researchers and clinicians.

To explore this issue, Daniel Andrews, a PhD candidate at McGill University, collaborated with neuroscientist Prof. Louis Collins and his team. They conducted simulated trials using publicly available Alzheimer’s patient data, replicating the demographics and constraints of the original lecanemab trial. Their findings supported the initial observation: lecanemab appeared to be less effective in women than in men. However, the researchers cautioned that there was insufficient evidence to conclude that the drug was entirely ineffective in women.

Dr. Louis Collins, who led the research team, commented, “Our findings highlight the importance of considering sex differences in drug trials. While lecanemab shows promise, clinicians need to weigh the potential benefits against the risks, especially for female patients.”

The study underscores the need for more nuanced approaches in clinical trials to account for sex differences in drug efficacy. As lecanemab continues to be prescribed, these findings could help clinicians make more informed decisions and may influence future drug approvals in other countries. Additionally, the research suggests ways to improve the design of future trials to better address sex-based variations in treatment outcomes.