The company said the death was of a patient enrolled at the initial dose level in the dose escalation portion. The study was testing the company’s XMT-2056 candidate.
The company is now focused on analyzing the death and “consider potential next steps for development,” Chief Executive Officer Anna Protopapas said in a statement.
The company will continue to make progress with the other cancer drug candidate UpRi and XMT-1660 clinical trials.
Shares of Mersana were halted before the bell.