Phase 3 Study of HyQ for Primary Immunodeficiencies

Baxter International announced study data from its Phase 3 study of HyQ for the treatment of patients with primary immunodeficiencies (PI). The study evaluated efficacy and safety as well as the pharmacokinetics, infusion volumes, intervals, and rates compared to patients' previous intravenous immunoglobulin (IGIV) administration. The prospective, open-label study enrolled 89 patients with PI in the US and Canada, and evaluated the effectiveness of HyQ in the prevention of infections and measured other secondary endpoints including tolerability. Study participants received recombinant human hyaluronidase (rHuPH20) administered subcutaneously followed by immunoglobulin (IG) 10% infused subcutaneously through the same needle at a dose of 108% of the patient's previously prescribed IG dose (administered intravenously).

In HyQ treated patients, serious validated bacterial infections (SBIs) occurred at an annualized rate of 0.025, which is lower than the threshold set by the FDA of <1 annually, and the annual rate of all infections was 2.97. Further, HyQ was bioequivalent to IGIV at 108% of the IV dose at three or four-week intervals. HyQ provided a lower peak IG concentration compared to IGIV, similar to weekly IGSC, with trough levels similar to every three or four-week IGIV treatment. Baxter has submitted applications for marketing approval of HyQ which has been accepted for review by the regulatory authorities.

HyQ is a combination product that includes immunoglobulin and recombinant human hyaluronidase, which are packaged as a kit. IG provides the therapeutic effect of HyQ and the recombinant human hyaluronidase facilitates the dispersion and absorption of the IG. The IG is a 10% solution that is prepared from large pools of human plasma and contains a broad spectrum of antibodies. The recombinant human hyaluronidase facilitates the increased bioavailability of IG by temporarily increasing the permeability of the subcutaneous tissue. 

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