Fresh data on Biogen (NASDAQ:BIIB) and Eisai's (OTCPK:ESALY) (OTCPK:ESALF) experimental Alzheimer's treatment lecanemab indicated that while the biologic led to moderately less decline in cognition and function compared to placebo, it was also associated with higher rates of brain swelling and bleeding.
The phase 3 study of nearly 1800 patients with early-stage Alzheimer's that lasted 18 months concluded that longer trials are needed to determine the efficacy and safety of lecanemab.
The study, published in the New England Journal of Medicine, was funded by the two companies. The FDA is set to act on lecanemab by Jan. 6.
Data showed that based on the Clinical Dementia Rating–Sum of Boxes (CDR-SB), an 18-point scale, those on lecanemab showed a cognitive decline an average of 1.21 points, compared to 1.66 points for those in placebo. That's a 27% difference.
For brain swelling, ~13% of lecanemab patients experienced brain swelling compared to 2% on placebo. The swelling was considered mild to moderate. For brain bleeding, the figures were, respectively, 17% and 9%.
In addition, six deaths were reported in the lecanemab group with seven in the placebo group. However, researchers said the deaths were not connected to lecanemab or associated with brain swelling or bleeding.
On Monday, the journal Science reported a death linked to lecanemab.