(Bloomberg) -- Eisai Co. said lecanemab, the drug it’s developing with Biogen Inc., isn’t to blame for two deaths involving brain bleeding that occurred in an Alzheimer’s disease treatment trial. 

Two people with severe brain hemorrhages died while receiving lecanemab in the trial and its extension period, when people who had been on placebo were offered the drug, Japan-based Eisai said in an email.  

“The two cases on lecanemab occurred in the open-label extension study,” the company said. “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.”

Eisai is preparing for a discussion Wednesday of detailed results of the final-stage trial, the first to show that a drug that removes the Alzheimer’s-liked protein called amyloid can slow the progress of the disease. Eisai’s shares fell 6.2% in Tokyo today after a report from Science magazine on the second of the two hemorrhage deaths among people who got the drug. The first death was earlier reported by STAT. 

Eisai had said earlier that it can be difficult to determine the cause of death in ill and elderly patients who’ve received other medicines. Biogen referred questions about the death to Eisai. 

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