In a phase 3 study, prophylaxis with the recombinant factor IX product nonacog alfa (BeneFIX) reduced bleeding in patients with hemophilia B.
Once-weekly prophylaxis with nonacog alfa significantly reduced the annualized bleeding rate (ABR) when compared to on-demand treatment with the drug.
Nonacog alfa was generally well tolerated, and none of the patients who received it developed inhibitors or experienced thrombotic events.
These results were published in Haemophilia. The study was sponsored by Pfizer, the company developing nonacog alfa.
The study was a sequential-period trial with a 6-month period of on-demand treatment followed by a 12-month period of prophylaxis, with a mean total therapy duration of 550 days.
All 25 male participants had moderately severe or severe hemophilia B (factor IX activity of 2 IU/dL or less), and their mean age was 31.3.
Participants had experienced at least 12 bleeding events, 6 of them in joints, in the previous year. All participants received nonacog alfa, and no one discontinued treatment early.
The median ABR values were 2.0 (range, 0.0-13.8) for the prophylaxis period and 33.6 (range, 6.1-69.0) for the on-demand treatment period. The mean ABR values were 3.6 ± 4.6 and 32.9 ±17.4, respectively (P<0.0001).
Bleeding occurred in 16 patients (64%) during the prophylaxis period and all 25 patients (100%) during the on-demand treatment period.
During the prophylaxis period, 13 patients (52%) experienced spontaneous bleeding events, with a mean ABR of 2.6. Thirteen patients (52%) experienced traumatic bleeding events, with a mean ABR of 1.0.
During the on-demand treatment period, 21 patients (84%) experienced spontaneous bleeding events, with a mean ABR of 23.1. Eighteen patients (72.0%) experienced traumatic bleeding events, with a mean ABR of 9.9.
Most bleeds had “excellent” (53.5%) or “good” (34.9%) responses to the first infusion of nonacog alfa, 10.8% had “moderate” responses, and 0.6% had no response. All bleeds responded to follow-up infusions.
The incidence of treatment-emergent adverse events was 96% in all patients—96% during the prophylaxis period and 64% during the on-demand treatment period.
The most common adverse events, occurring in at least 10% of patients during either regimen, were arthralgia (24%), back pain (12%), headache (36%), joint swelling (20%), local swelling (12%), nasopharyngitis (12%), pharyngitis (20%), pyrexia (20%), toothache (24%), and upper respiratory tract infection (24%).
