Chugai shares fall after deaths among Actemra users

TOKYO, March 18 (Reuters) - Shares in Chugai Pharmaceutical Co 4519.T, the Japanese unit of Swiss drugmaker Roche Holding AG ROG.VX, fell as much as 11 percent after Chugai reported 15 deaths among people that had used the Actemra arthritis drug.

Japan was the first country to approve Actemra for rheumatoid arthritis, viewed by Roche as a potential blockbuster. Actemra has won approval in Europe in January, but has yet to be approved in the United States. [ID:nLL414111] [ID:nWNAB9431]

Chugai said in a report on its website that among 4,915 rheumatoid arthritis patients who had been injected with Actemra between April 2008 and February 2009, there had been 15 deaths where it could not deny the possibility of a link to the use of Actemra.

“The fact that the causal relationship was not denied means there is a possibility that Actemra may have had an impact,” said Chugai spokesman Masayuki Yamada.

“So, we would like to keep collecting information and analysis and provide timely information to medical institutions and others.”

Chugai also said there had been 221 cases of serious side-effects.

Chugai's stock fell as much as 11 percent, though it later trimmed those losses to be down 7.4 percent at 1,474 yen. The benchmark Nikkei average .N225 was down 0.2 percent.

It was not the first time that Chugai had published a report on side effects of the drug. It has been periodically updating that information, including reported deaths, on its website, Yamada said.

Known chemically as tocilizumab, Actemra is an anti-interleukin-6 receptor antibody and works in a different way than the existing multibillion-dollar-selling class of biotech drugs for arthritis that block an inflammatory protein called tumor necrosis factor (TNF).

Roche holds nearly 60 percent of Chugai. (Reporting by Taiga Uranaka and Nathan Layne; Editing by Edwina Gibbs)