The FDA has approved Afstyla (antihemophilic factor [recombinant], single chain, CSL Behring), a recombinant factor VIII single-chain therapy for adults and children with hemophilia A. Afstyla is the first single-chain product for hemophilia A that is specifically designed for long-lasting protection from bleeds with two- to three-times weekly dosing.
In clinical trials, patients undergoing prophylaxis with Afstyla experienced a median annualized spontaneous bleeding rate (AsBR) of 0.00. Once activated, Afstyla is identical to natural factor VIII. The treatment is indicated in adults and children with hemophilia A for routine prophylaxis to reduce the frequency of bleeding episodes; for on-demand treatment and control of bleeding episodes; and for the perioperative management of bleeding. It is expected to be available early this summer.
The approval of Afstyla was based on results from the AFFINITY clinical development program. AFFINITY included two pivotal and one extension open-label studies evaluating the safety and efficacy of Afstyla in children, adolescents, and adults with hemophilia A.
The data from the AFFINITY program showed a median AsBR of 0.00 in both the adult and adolescent studies as well as the pediatric study. The median annualized bleeding rate (ABR) was 1.14 in adult and adolescent patients and 3.69 in children less than 12 years of age using Afstyla prophylactically. Of 1,195 bleeds treated in the pivotal study (848 bleeds in adults and adolescents, and 347 bleeds in children), 94% of bleeds in adult and adolescent patients and 96% of bleeding events in pediatric patients were effectively controlled with no more than two infusions of Afstyla weekly; 81% of bleeds in adult and adolescent patients and 86% of bleeding events in pediatric patients were effectively controlled by only one infusion.
Most of the bleeding events treated with Afstyla (94% in adults and adolescents, and 96% in children) were rated as excellent or good. Of the 13 adult or adolescent patients who underwent surgical procedures (16 total surgeries), the hemostatic efficacy of Afstyla was rated as excellent (15 times) or good (once). The most common adverse events reported in clinical trials were dizziness and hypersensitivity.
Afstyla (also known as rVIII-single chain) is a recombinant single-chain factor VIII specifically designed for greater molecular stability and longer duration of action. Afstyla uses a covalent bond that forms one structural entity, a single polypeptide-chain, to improve the stability of factor VIII and to provide longer-lasting factor VIII activity.
Source: CSL Behring; May 26, 2016.