Alnylam Shares Sink After Hemophilia Patient Dies in Study

Alnylam Pharmaceuticals Inc. shares plunged Sept. 7 after the company halted studies of its lead experimental drug for hemophilia following the death of a patient.

The development-stage biotechnology company and its partner Sanofi suspended dosing of the drug fitusiran to review the patient’s death, which it said may have been triggered by a blood clot in his brain, and develop a program to monitor and mitigate risks.

The Cambridge, Mass.-based company said in a statement that it aims to resume treating patients as soon as possible, perhaps by the end of the year, pending agreement with regulators.

Shares of Alnylam ...