Well-Controlled Bleeding with rVIII-SingleChain

Adults and adolescents with hemophilia A had well controlled bleeding when dosed two or three times weekly with recombinant factor VIII single chain (rVIII-SingleChain), according to a study presented during the Late Breaking Session at the 2015 International Society on Thrombosis and Haemostasis Congress.

Researchers from CSL Behring compared octocog alfa and the novel investigational rVIII-SingleChain in order to test the continuation of dosing safety and efficacy for adults and adolescents with hemophilia A. More than 14,000 exposure days in 146 prophylaxis patients and 27 patients with on demand treatment were included in the study. The researchers treated 120 patients for more than 50 days of exposure, and there were 52 patients with more than 100 days of exposure. About a third of the prophylaxis group was dosed twice weekly and about half received three times weekly dosing.

The rVIII-SingleChain patients had low annualized bleeding rates (ABR), with a median ABR of 1.14 and an annualized spontaneous bleeding rate (AsBR) of 0.00, the researchers found. When compared to octocog alfa, the researchers said rVIII-SingleChain demonstrated improved pharmacokinetic parameters. The investigators treated 848 bleeds throughout the course of the study, 94 percent of which were successfully controlled with no more than two doses of rVIII-SingleChain, and 81 percent of bleeds were controlled with just one infusion.

“We observed relatively low ABR and a median of zero spontaneous bleeding events with rVIII-SingleChain for routine prophylaxis for patients with hemophilia A,” lead investigator Professor Ingrid Pabinger-Fasching, MD, of the Medical University of Vienna, Austria, explained in a press release. “As the first and only single chain recombinant factor product, rVIII-SingleChain has the potential to offer improved protection from bleeding with less frequent dosing, and an excellent safety profile thus far.”

The researchers said that the most common adverse events in the rVIII-SingleChain treatment group were naso pharyngitis, arthralgia, and headache.

The investigators treated 94 percent, or 835 bleeds, with rVIII-SingleChain and rated the control as “excellent” or “good.” The research was part of a larger study, the Affinity Phase I/ III study, which is an open label, multicenter trial examining the safety, efficacy, and pharmacokinetics of rVIII-SingleChain compared to octocog alfa.

“Our novel rVIII-SingleChain was specifically designed to improve the stability and provide longer lasting hemostatic efficacy of factor VIII, thereby addressing the need to provide hemophilia A patients with a treatment that may require fewer infusions while maintaining its therapeutic effect,” Dr. Andrew Cuthbertson, Chief Scientific Officer and Director of R&D, CSL Limited, continued in the statement. “These pivotal data are promising and are supportive of CSL Behring’s commitment to bringing this therapy to the market, and to helping improve the care of people living with hemophilia A.”