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Alnylam Announces FDA Lift of Hold on Fitusiran Trials

December 18, 2017
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The US Food and Drug Administration (FDA) has lifted a hold on clinical studies involving the investigational therapy fitusiran, which is being developed by Alnylam to treat patients with hemophilia A and B, both with and without inhibitors. Alnylam and Sanofi Genzyme announced the change in an Alnylam press release on December 15, 2017.

Trials involving fitusiran were suspended in September 2017 after the confirmed death of a hemophilia A patient who had been receiving the therapy as part of a Phase 2 open label extension study.

Fitusiran is a subcutaneous therapy (administered under the skin) that employs small interfering RNA (siRNA) technology to target antithrombin (AT), a liver-generated clotting protein that plays a key role in the regulation of blood clots. siRNA molecules are segments of RNA (ribonucleic acid) that block or “silence” the activity of certain genes through RNA interference, a natural biological process common in plants and mammals. Fitusiran works by silencing the gene responsible for AT, which inhibits the protein’s anticoagulant function. This then compensates for the imbalance caused by deficiencies in other clotting proteins, such as factor VIII (hemophilia A) or factor IX (hemophilia B).

The suspension was lifted following a successful Type A meeting between the FDA and Alnylam this fall wherein “alignment” was achieved. Type A meetings are employed by the FDA after a clinical hold is put in place, so that both applicants and the regulatory agency may discuss a path forward. These type meetings, as they did in this case, often produce amended protocols and trial materials.  

“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, PhD, 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.”

Source: Alnylam press release dated December 15, 2017