Japanese drugmaker Eisai's shares drop on report of death in Alzheimer's trial

TOKYO (Reuters) - Shares in Japanese drugmaker Eisai Co fell more than 6% on Tuesday after a report that a woman who was enrolled in a trial of the company's Alzheimer's disease treatment had died from brain haemorrhage.

The haemorrhage occurred after the woman, who was receiving the experimental drug developed by Eisai and U.S. partner Biogen Inc, suffered a stroke and was given a medicine known as tissue plasminogen activator (tPA) to clear blood clots, journal Science.org reported on Sunday.

Some analysts said it was not clear if use of the drug, lecanemab, was raising the risk of bleeding, and cautioned against the use of blood thinners with the drug.

"We think the interpretation that lecanemab is the causative factor is aggressive. This patient clearly went into crisis following tPA administration," Baird analyst Brian Skorney said in a note.

This is the second media report of a death among patients who were enrolled in the lecanemab trial. A man in his 80s who was receiving a blood thinner died in June, according to a report by health journal STAT in late October.

Eisai said in a statement on Monday that all available safety information indicates lecanemab therapy is not associated with an increased risk of death overall. It said it could not provide any information about specific patients "to protect the privacy of patients".

Shares of Eisai dropped 6.2% to 8,988 yen on Tuesday, leading decliners on the benchmark Nikkei index, which closed 0.5% lower. Shares in Biogen fell 4.3% on Monday.

Biogen and Eisai are expected to present detailed data from their late-stage study results later in the day.

Lecanemab was shown to slow cognitive and functional decline in a large trial of patients in the early stages of Alzheimer's disease, the companies said in September.

(This story has been officially corrected to change publication from Science to Science.org in paragraph 2)

(Reporting by Rocky Swift in Tokyo and Raghav Mahobe and Khushi Mandowara in Bengaluru; Editing by Cynthia Osterman and Devika Syamnath)