Use of Efmoroctocog Alfa in Children and Adolescents: Clinical Observations

Abstract

Despite availability of prophylactic therapy for hemophilia A with factor VIII concentrates with a standard half-life, patients continue to experience episodes of bleeding and joint damage. The reasons for this may be the relatively short half-life of the factor VIII drug and the low adherence of patients to treatment. The appearance of clotting factor concentrates with an extended half-life makes it possible to reduce the frequency of infusions and increase the residual activity of the deficient factor. The article presents clinical observations of the use of Efmoroctocog alfa (recombinant human coagulation factor VIII, Fc fusion protein (rFVIIIFc)) in a 16-year-old adolescent and a 7-year-old child with severe and moderate forms of hemophilia A. In order to select the most rational therapy regimen and evaluate the effectiveness of treatment, the authors have conducted individual assessments of patients’ pharmacokinetic (PK) parameters. The drug administration in both patients was twice per week. To assess individual PK, the WAPPS-Hemo was used in order to calculate individual PK parameters based on a small plasma samples collected during routine prophylactic treatment. During the PK study, 3 blood samples were taken to determine the level of factor VIII in a one-step method. In a 16-year-old patient, the half-life of Efmoroctocog alfa (t1/2) was 24.25 hours. The activity of factor VIII prior to the next injection was 7.4%. In addition, 81% of time the factor VIII activity was above 15%. In a 7-year-old patient, the t1/2 of the drug was 12.75 hours. The minimum residual activity of factor VIII was 2.1%, 86% of time the activity of factor VIII was above 3%. Conclusion: high efficacy and safety were demonstrated based on the results of the use of Efmoroctocog alfa in routine clinical practice in previously treated pediatric and adolescent patients with severe and moderate hemophilia A, as well as the reduction in the frequency of infusions per week from 3 to 2.