Rare Daily Staff

Alnylam Pharmaceuticals and Sanofi Genzyme said the U.S. Food and Drug Administration has lifted the hold on clinical studies with fitusiran, their experimental RNAi therapeutic for hemophilia, including the mid-stage open-label extension study and the a late-stage program.

Alnylam and the FDA had previously reached agreement on new clinical risk mitigation measures, including protocol-specified guidelines and additional investigator and patient education concerning reduced doses of replacement factor or bypassing agent to treat any breakthrough bleeds in fitusiran studies. The FDA has now approved the protocol amendments and other updated clinical materials for fitusiran studies.

In September, Alnylam halted dosing in ongoing trials of fitusiran following the death of a 78-year-old man with hemophilia A in the mid-stage open label extension.

Hemophilia is a hereditary bleeding disorder caused by a genetic mutation that results in inadequate levels of thrombin, an enzyme that causes clotting. Fitusiran is an experimental RNAi therapy that is administered once-monthly. It targets antithrombin, a protein that inactivates certain enzymes involved in coagulation. Fitusiran is designed to lower levels of antithrombin with the goal of promoting sufficient thrombin generation to restore hemostasis and prevent bleeding in patients with hemophilia A or B.

“We are pleased with the FDA’s decision to lift the clinical hold, as fitusiran holds the potential to help improve the lives of people living with hemophilia,” said Akin Akinc, Vice President and General Manager, Fitusiran at Alnylam. “With the additional risk mitigation measures in place, we look forward to the continued late-stage development of fitusiran and expect to resume dosing around year-end.”

December 15, 2017