U.S. FDA halts enrollment in Mersana’s cancer drug studies, shares fall

U.S. FDA halts enrollment in Mersana’s cancer drug studies, shares fall

June 15 (Reuters) – Mersana Therapeutics (MRSN.O) said on Thursday the U.S. Food and Drug Administration (FDA) had paused enrollment in two studies of its ovarian cancer drug after five deaths in bleeding-related events, sending shares of the company tumbling.

Mersana said the cause of the bleeding events was under investigation, but patients who are already enrolled in the studies will continue to receive the treatment.

Shares of the company, which had a market capitalization of $1.09 billion as of Wednesday’s close, fell 62% to $3.58 in premarket trading.

The drugmaker said it expects the FDA to ask for a comprehensive assessment of the safety data of UpRi, Mersana’s lead drug.

“Work is now underway to compile further analyses that may inform FDA,” Mersana CEO Anna Protopapas said.

UpRi is also being tested in another ovarian cancer study, which has already completed enrollment, and data from it is expected in August.