The drug, lecanemab, was associated with a type of brain swelling in 12.6% of trial patients, a side effect previously seen with similar drugs. Fourteen percent of patients had microhemorrhages in the brain – a symptom linked to two recent deaths of people receiving lecanemab in a follow-on study – and five patients suffered macrohemorrhages.
Eisai shares climbed 3% Tokyo Wednesday morning while Biogen shares were 0.9% higher in after-hours trade. They have jumped some 60% and 47% respectively since the announcement of the trial’s initial findings in late September. “For that small group of homozygous patients, when it comes to CDR-SB we don’t see a signal favoring lecanemab,” Ivan Cheung, Eisai’s U.S. chairman, said in an interview. He suggested that could be because homozygous study patients who were given a placebo fared better than expected.
Detailed data from the study were presented at the Clinical Trials on Alzheimer’s Disease meeting in San Francisco.Eisai believes the trial results prove a longstanding theory that removal of sticky deposits of a protein called amyloid beta from the brains of people with early Alzheimer’s can delay its advance.