Sanofi Genzyme, the specialty care global business unit of Sanofi, and Alnylam Pharmaceuticals, the leading RNAi therapeutics company, announced that the US Food and Drug Administration (FDA) has lifted the hold on clinical studies with fitusiran, including the phase 2 open-label extension (OLE) study and the ATLAS phase 3 programme.

Alnylam and the FDA had previously reached alignment 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. Fitusiran is an investigational RNAi therapeutic targeting antithrombin (AT) for the treatment of patients with hemophilia A and B. It is designed to lower levels of AT with the goal of promoting sufficient thrombin generation to restore hemostasis and prevent bleeding.

"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, Ph.D., 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."

The clinical significance of the fitusiran mechanism of action is under investigation. Fitusiran has not been approved by the FDA, EMA or any other regulatory authority for any indication and no conclusions can or should be drawn regarding the safety or effectiveness of this investigational therapeutic.

Sanofi has an alliance with Alnylam Pharmaceuticals to co-develop and co-commercialize fitusiran in the United States, Canada and Western Europe. In addition, Sanofi has the exclusive right to commercialize fitusiran in the rest of the world.