DEERFIELD, Ill., Jan. 5, 2012 /PRNewswire/ -- Baxter International Inc. today announced the dosing of the first patients in a Phase I clinical trial of its lead investigational candidate, BAX 855, a longer-acting (PEGylated) form of a full-length recombinant factor VIII (rFVIII) protein. BAX 855 is based on Baxter's ADVATE [Antihemophilic Factor (Recombinant) Plasma/Albumin-Free Method] full-length rFVIII molecule and plasma/albumin-free (PAF) manufacturing process. The Phase I trial is a prospective, open-label study that will assess the safety, tolerability and pharmacokinetics of BAX 855 in previously-treated patients aged 12 years or older with severe hemophilia A. When used for prophylaxis, Baxter's ADVATE requires patients to infuse every two to three days to reduce the occurrence of bleeding episodes. This Phase I trial is the first step in assessing whether BAX 855 can be infused less frequently. "This trial is designed to provide new insights about our investigational longer-acting FVIII molecule, BAX 855, with the ultimate goal of improving care for patients living with hemophilia A," said Prof. Hartmut J. Ehrlich, M.D., vice president of global research and development in Baxter's BioScience business. "The Phase I results will serve as the foundation for advancing this important program through clinical development and determining whether BAX 855 can offer a treatment regimen requiring fewer infusions than ADVATE." BAX 855 employs Baxter's proprietary full-length plasma/albumin-free recombinant protein platform that does not contain any human or animal-derived additives. BAX 855 leverages Nektar Therapeutics' (NASDAQ: NKTR) proprietary PEGylation technology, which is designed to extend the duration of activity of proteins and larger molecules. Baxter and Nektar have a collaboration to develop PEGylated products designed to provide new long-acting therapies for hemophilia patients. ADVATE was recently approved for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in patients with hemophilia A. With the inclusion of prophylaxis in the adult patient population, ADVATE became the only antihemophilic factor approved in the United States for prophylactic use in both children and adults. This approval was supported by a Phase IV prophylaxis study sponsored by Baxter demonstrating that ADVATE for routine prophylaxis significantly reduced median annual bleed rates (ABR) in hemophilia A patients. In the study, patients experienced 44 bleeds (per patient per year) during on-demand treatment compared to one bleed (per patient per year) while on either of the prophylactic regimens evaluated, a 98 percent reduction in annual bleed rate (p<0.0001). Nearly half (42 percent) of patients experienced zero bleeding episodes during one year on prophylactic therapy. Evaluable patients were those with at least 90 percent adherence to their prescribed prophylactic regimen. About ADVATE ADVATE was initially approved by the FDA in July 2003 for control and prevention of bleeding episodes in adults and children with hemophilia A.