- Alnylam Pharmaceuticals, still suffering from a clinical trial blow-up earlier this year, scored a win over the weekend with strong data from a Phase 1 study of its experimental hemophilia treatment fitusiran.
- Presenting at the annual meeting of the American Society of Hematology, Alnylam said its investigational drug fitusiran helped control bleeding in a subset of hemophilia patients who typically are hard to treat.
- Alnylam plans to move quickly into a Phase 3 study in early 2017. Fitusiran's safety and efficacy profile to date could make it a competitive threat to Roche's experimental hemophilia drug emicizumab.
At ASH, Alnylam presented data from both its Phase 1 trial of fitusiran among hemophilia patients with inhibitors — antibodies that hinder treatment with replacement factor — and its Phase 2 open-label extension study of patients without inhibitors.
Alnylam reported encouraging results on both fronts in two updates which Jefferies, an investment firm, called the "nearly best case scenario" for the company.
In the Phase 1 study, nine of the 16 patients treated before the ASH data cut-off were bleed free, resulting in an estimated median annualized bleeding rate of 0. This compares favorably to the pre-study median of 31.
Importantly, no thromboembolic events were observed, even when bypassing agents were used to treat breakthrough bleeds. By comparison, Roche recently reported four thromboembolic events in its studies of emicizumab, leading to concerns over safety.
With a clean safety profile and strong efficacy results, fitusiran could challenge emicizumab even though Roche will likely shepherd it to market sooner.
In the open-label study, treatment with fitusiran led to a median annualized bleeding rate of 1 among patients without inhibitors — data largely consistent with prior studies, according to Jefferies.
Alnylam believes fitusiran's once-monthly, subcutaneous dosing will present a competitive advantage over existing treatments of hemophilia, which are typically administered more frequently through an IV.
Fitusiran, like other drugs in Alnylam's pipeline, is based on RNA interference, designed to silence genes which produce disease-causing proteins. While the field has shown promise, recent setbacks at Alynlam and Arrowhead Pharmaceuticals have dented optimism.