(HealthDay News) — For males aged 12 years or older with severe hemophilia A or B with or without inhibitors, the annualized bleeding rate is lower with fitusiran prophylaxis, according to two studies published online March 29 in The Lancet and The Lancet Hematology.
Guy Young, M.D., from the University of Southern California in Los Angeles, and colleagues conducted an open-label phase 3 study at 26 sites in 12 countries involving 57 males aged 12 years or older with severe hemophilia A or hemophilia B with inhibitors previously treated with on-demand bypassing agents. Participants were randomly assigned to once-a-month 80 mg subcutaneous fitusiran prophylaxis or to continue bypassing agents on demand for nine months (38 and 19 patients, respectively). The researchers found that the mean annualized bleeding rate was significantly lower in the fitusiran prophylaxis group than in the bypassing agents on-demand group (1.7 versus 18.1), corresponding to a 90.8 percent reduction.
Alok Srivastava, M.D., from the Christian Medical College in Vellore, India, and colleagues conducted a phase 3 study at 45 sites in 17 countries involving 120 male participants aged at least 12 years with severe hemophilia A or B without inhibitors, who had previously been treated on demand with clotting factor concentrates. Participants were randomly assigned to 80 mg subcutaneous fitusiran prophylaxis once per month or to continue on-demand clotting factor concentrates for nine months (80 and 40 patients, respectively). The researchers found that the estimated annualized bleeding rate was 3.1 and 31.0 in the fitusiran and on-demand clotting factor concentrates groups, respectively (rate ratio, 0.101).
“To our knowledge, fitusiran prophylaxis is the first therapy to show hemostatic efficacy in both hemophilia A or B, regardless of inhibitor status, and therefore has the potential to be transformative in the management of all people with hemophilia,” Srivastava and colleagues write.
Several authors disclosed financial ties to pharmaceutical companies, including Sanofi, which manufactures fitusiran and funded both studies.