Baxter Reports Data from Extended Half-Life Study

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Baxter International Inc. presented additional efficacy and safety data from the Phase III pivotal study of BAX 855, an investigational, extended half-life recombinant factor VIII (rFVIII) treatment for hemophilia A based on ADVATE [Antihemophilic Factor (Recombinant)] at the 8th Annual Congress of the European Association for Haemophilia and Allied Disorders (EAHAD) in Helsinki, Finland.
The new data expand on the previously disclosed topline results from the pivotal trial, which found that BAX 855 met the study’s primary endpoint in the control and prevention of bleeding episodes and routine prophylaxis. Patients in the twice-weekly prophylaxis arm of the trial experienced a 95 percent reduction in median annualized bleed rate (ABR) as compared to those in the on-demand arm (1.9 vs. 41.5, respectively). The study findings supported Baxter’s December 2014 submission for approval of BAX 855 to the United States Food and Drug Administration (FDA).
“These pivotal trial results provide evidence to support the efficacy profile of BAX 855 in controlling, preventing or reducing the frequency of bleeding episodes when administered prophylactically twice weekly. Our goal with BAX 855 is to extend the interval between infusions while maintaining a similar efficacy profile to ADVATE,” said John Orloff, M.D., vice president and global head of research and development for Baxter BioScience.
The prospective, global, multi-center, open-label, two-arm Phase III study evaluated BAX 855 among 137 previously treated hemophilia A patients (PTP) who were 12 years or older. Patients were assigned either to twice weekly prophylaxis (40-50 IU/kg, n=120) or on-demand treatment (10-50 IU/kg, n=17). In addition to a reduced ABR, BAX 855 was also effective in treating bleeding episodes, 96 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 episodes (96.2%). In the prophylactic group (n=101), 40 percent of patients experienced no bleeds. The study also showed that BAX 855 pharmacokinetics offered a 1.4-1.5-fold extended half-life compared to 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, were reported. Seven adverse reactions in six patients, including headache, diarrhea, nausea, and flushing were reported.
Baxter’s continuation study for patients who completed the pivotal trial and the Phase 3 study among previously treated patients under the age of 12 with severe hemophilia A remain ongoing. Upon completion of the pediatric study, Baxter expects to file for marketing authorization with the European Medicines Agency in 2016.
BAX 855 is based on ADVATE, a full-length FVIII molecule with more than 11 years of real-world patient experience. Through a collaboration with Nektar Therapeutics (NASDAQ: NKTR), BAX 855 leverages proprietary PEGylation technology designed to prolong the amount of factor VIII available for use in the body. This proprietary technology has been used for 15 years in a number of approved medicines that treat chronic or serious conditions.
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