Managing Safety in Fitusiran Treatments of Hemophilia: Guy Young, MD

“Once there's sufficient data with this new dosing schema, then hopefully that data will then be evaluated, published and presented. If it looks reasonable enough, that could be how this drug will be packaged to the FDA for hopefully getting it licensed in the future.”

The antithrombin-targeted, siRNA therapeutic fitusiran reduced bleeding in people with hemophilia A or B with or without inhibitors treated with prophylactic doses compared with those only given on-demand treatment.

Fitusiran was evaluated in the phase 3 ATLAS-INH study (NCT03417102), data from which were presented at the 63rd Annual American Society of Hematology (ASH) Meeting, December 11-14, 2021, by Guy Young, MD, director, Hemostasis and Thrombosis Program, Children’s Hospital of Los Angeles and professor of Pediatrics, Keck School of Medicine, University of Southern California.

Fitusiran reduced bleeding to 0 bleeding events in most patients in the fitusiran arm with both hemophilia A and B (n = 25; 65.8%) after treatment. Primary endpoints were met, as these patients achieved statistical significance in reduced annual bleeding rate (ABR) of treated bleeds as well as a reduction in all, spontaneous, and joint bleeds. Higher physical health domain and health-related quality of life scores were also observed in participants treated with fitusiran (both P <.0001). Adverse events (AEs) were common and 17.1% (n = 7) of patients reported serious AEs.

CGTLive spoke with Young to learn more about the safety profile of fitusiran and how investigators are mitigating these AEs by modifying trial protocols. He discussed how mitigation strategies should be employed in the future if the candidate comes to market.

REFERENCE

Young G, Srivastava A, Kavkli K, et al. Efficacy and safety of fitusiran prophylaxis, an siRNA therapeutic, in a multicenter phase 3 study (ATLAS-INH) in people with hemophilia A or B, with inhibitors (PwHI). Presented at: 63rd Annual ASH Meeting; December 11-14, 2021, Atlanta, GA. Abstract 4.