An investigational recombinant Factor VIII single chain demonstrated strong efficacy and a good safety profile in a large cohort of patients with severe hemophilia A, according to study results presented at the International Society of Thrombosis and Haemostasis Congress.
RVIII-SingleChain (CSL Behering) — a novel B-domain truncated recombinant Factor VIII — also showed superior pharmacokinetic activity than antihemophilic factor (recombinant) [Advate, Baxter], results showed.
Prior studies showed rVIII-SingleChain has higher binding affinity to von Willebrand Factor, a longer half-life, a lower clearance, a higher mean residence time and a larger area under the curve than Advate, according to study background.
Ingrid Pabinger-Fasching, MD, professor at Medical University of Vienna in Austria, and colleagues conducted the open-label, multicenter AFFINITY study to assess the efficacy, safety and pharmacokinetics of rVIII-SingleChain for the prevention and treatment of bleeding episodes in adults and adolescents with severe hemophilia A.
The analysis included 173 patients who underwent treatment; of these, 146 received prophylaxis and 27 received on-demand treatment.
The study comprised more than 14,200 exposure days; 120 patients had more than 50 days of exposure, and 52 patients had more than 100 days of exposure.
Researchers evaluated 830 treated bleeds; of these, 81% were controlled by one infusion of rVIII-SingleChain and 94% were successfully controlled with no more than two infusions.
World Federation of Hemophilia guidelines guided the dosing. In the prophylaxis group, 54% of patients received three doses per week, 32% of patients received two doses per week, 6% received doses every other day, and 8% followed other dosing regimens.
Pabinger-Fasching and colleagues calculated a median annual bleed rate of 1.14 and an annualized spontaneous bleeding rate of 0 in the prophylaxis group.
Researchers observed no inhibitor development in the study population. The agent also appeared well tolerated, according to the investigators. The most common adverse events included naso-pharyngitis, arthralgia and headache.
“In this large-scale study, we observed relatively low annualized bleeding rates and a median of zero spontaneous bleeding events with rVIII-SingleChain for routine prophylaxis for patients with hemophilia A,” Pabinger-Fasching said 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.” – by Mark Leiser
For more information:
Mahlangu J, et al. Abstract LB008. Presented at: International Society of Thrombosis and Haemostasis 2015 XXV Congress; June 20-25, 2015; Toronto.
Disclosure: The researchers report employment relationships with CSL Behring.