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Extended Hemophilia Therapy Lowers Bleeding Rates in Trial

Blood bag (NIH)

(National Institutes of Health)

22 August 2014. Results from a late-stage clinical trial show an extended-life therapy to control hemophilia reduces rates of bleeding among patients when used as a preventive medication. The biologic tested in the trial is an extended release version of Advate, an engineered form of blood coagulant proteins made by Illinois-based drug maker Baxter International in collaboration with Nektar Therapeutics in San Francisco.

Hemophilia is an inherited disorder, where the proteins needed to mix with platelets to allow blood to coagulate are missing. About 8 in 10 people with the condition have hemophilia type A, where the protein clotting factor 8 is missing. In type B, clotting factor 9 is missing.

Advate is Baxter’s engineered form of clotting factor 8 given as an injection to control and prevent bleeding episodes in children and adults, with the dose and frequency determined by type of episodes, and age and weight of the patient. FDA approved the drug for sale in the U.S. in 2003.

The clinical trial tested a version of Advate with the code-name BAX855 that applies a technology by Nektar Therapeutics to extend the release of the drug in the body. The Nektar technology uses biocompatible polymers that decrease liver metabolism and reduce clearance by the kidneys, thus extending the exposure of the drug and in some cases reducing the drug’s toxicity. A longer exposure of Advate in this case can mean less-frequent injections for the patient.

The study enrolled 138 patients with hemophilia A, age 12 to 65, at 72 locations in the U.S., Europe, Israel, and Asia. The trial tested two different strategies for administering BAX855: as a preventive medication given twice a week or an on-demand treatment to control bleeding, over a 9-month period. The main efficacy measure was annualized bleed rate, or number of bleeding episodes during the test period, extrapolated to 12 months.

The trial also measured success rates in treating bleeding episodes on demand, as well as number of infusions needed to treat those episodes. In addition, the study looked at the exposure of the patients to BAX855 versus regular Advate, as measured by the half-life of factor 8 in plasma.

The results show patients taking BAX855 as a preventive medication had a median annualized bleed rate of 1.9 compared to a rate of 41.5 for those taking BAX855 on demand, a 95 percent lower rate. However, for those taking BAX855 on demand, the therapy was able to control 96 percent of bleeding episodes with 1 or 2 infusions.

And the drug exposure among BAX855 users showed the half-life of the therapy was 1.4 to 1.5 times longer than regular Advate. No serious adverse reactions from the treatments were reported, and the only side effects were headaches among 3 participants.

Baxter says it expects to file a Biologics License Application with FDA for BAX855 before the end of the year. FDA in June approved an extended-release preventive drug for hemophilia A made by Biogen Idec.

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Hat tip: FirstWord Pharma

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