Baxalta announces publication of phase II/III results for BAX 855 (Adynovate) for hemophilia A

Baxalta announced the publication of the complete data from the Phase II/III pivotal study and Phase I trial of BAX 855 in Blood, the journal of the American Society of Hematology. BAX 855 is Baxalta's investigational extended half-life recombinant factor VIII (rFVIII) treatment for haemophilia A based on Advate [antihaemophilic factor (recombinant)], a leading treatment for haemophilia A with more than 11 years of real-world patient experience.

Following on initial presentations of the data in 2014, the publication provides a comprehensive overview of the clinical trial results of BAX 855, which will be marketed in the United States under the brand name Adynovate [antihaemophilic factor (recombinant), pegylated] upon approval. The trial assessed the treatment's safety and efficacy profiles for bleed prevention with a twice-weekly dosing schedule, showing a mean half-life extension of 1.4- to 1.5-fold compared with Advate. The positive study results were originally reported in August of 2014 and supported the company's December 2014 submission for approval of BAX 855 to the FDA.

The prospective, global, multi-center, open-label, two-arm Phase II/III study evaluated BAX 855 among 137 previously treated patients (PTP) with haemophilia A who were aged 12 to 65. Patients were assigned to either twice weekly prophylaxis (40-50 IU/kg, n=120) or on-demand treatment (10-60 IU/kg, n=17). As previously disclosed, BAX 855 met the study's primary endpoint for the prevention of bleeding episodes and the treatment with prophylaxis compared to on-demand treatment. Patients in the twice-weekly prophylaxis arm of the trial experienced a 95 percent reduction in median annualized bleed rate (ABR) as compared with those in the on-demand arm (1.9 vs. 41.5, respectively). BAX 855 was also effective in treating all bleeding episodes, 95.9 percent of which were controlled with one or two infusions at a median dose of 29.0 IU/kg per infusion. Treatment was rated excellent or good for nearly all bleeding episodes (96.1 percent). In the prophylactic group (n=101), 39.6 percent of compliant patients experienced no bleeds. The study also showed that BAX 855 pharmacokinetics offered a 1.4 to 1.5-fold mean extended half-life compared with Advate with a median infusion interval of 3.6 days, supporting the findings from the Phase I trial. No patients developed inhibitors to BAX 855 and no treatment-related serious adverse events, including hypersensitivity reactions, were reported. Seven adverse reactions in six patients, including headache, diarrhea, nausea, and flushing were reported.

Comment: Upon approval, BAX 855 will offer patients a twice-weekly dosing option with proven efficacy based on Advate, a leading standard of care for haemophilia. Baxalta (then Baxter) filed BAX 855 at the FDA in December 2014.