Eisai said lecanemab, its Alzheimer's drug candidate that Biogen is co-marketing, did not cause trial participants to hemorrhage and die.
"Eisai has established a rigorous safety monitoring process to ensure patient safety," the Japanese drugmaker said in a Nov. 29 news release. "This includes an independent data safety monitoring committee of external experts. All the available safety information indicates that lecanemab therapy is not associated with an increased risk of death overall."
Biogen said "no deaths were related to lecanemab."
At least two people taking lecanemab died after experiencing swelling and bleeding in the brain. The first death was disclosed Oct. 28, and Science reported the second one Nov. 27. Two days after the Science article was published, Eisai and Biogen presented the full trial's results — which slowed cognitive decline by 27 percent among a phase 3 trial of 1,795 people.
Serious side effects were reported among 14 percent of study participants who took lecanemab and 11.3 percent of those who took a placebo. Among the less than 10 percent of the people taking lecanemab who experienced adverse effects, 17.3 percent had hemorrhages, compared to 9 percent of the placebo group.
"Rates of deaths with concurrent cerebral macrohemorrhage were 0.1 percent in both the placebo group (1/897) and the lecanemab group (2/1,608)," Biogen said. "The two cases on lecanemab occurred in the open-label extension study. Both cases had significant comorbidities and risk factors including anticoagulation contributing to macrohemorrhage or death. Therefore, it is Eisai's assessment that the deaths cannot be attributed to lecanemab."