Objective:
BAY 81-8973 (Kovaltry®) is a full-length, unmodified recombinant human factor VIII (FVIII) for prophylaxis and treatment of bleeds in patients with hemophilia A. Safety and efficacy of BAY 81-8973 in children, adolescents, and adults were established in the LEOPOLD clinical trials. This analysis reports interim data from the LEOPOLD Kids extension study for patients with ≥100 exposure days (EDs) to BAY 81-8973 in the main study plus extension study.
Methods:
In LEOPOLD Kids, boys aged ≤12 years with severe hemophilia A and ≥50 EDs to FVIII received BAY 81-8973 (25–50 IU/kg) ≥2 times/wk for ≥50 EDs. Patients completing the main study could enroll in an ongoing extension study for ≥100 EDs.
Summary:
Of 51 patients who completed the main study, 46 (90.2%) entered the extension study (aged <6 years, n=22; aged 6–12 years, n=24). Patients were treated for a median (range) of 1494 (175–1989) days and accumulated 546 (67–1011) EDs in the extension study. Median (quartile [Q]1; Q3) dose per prophylaxis infusion was 37.7 (33.1; 41.8) and 30.9 (29.1; 34.9) IU/kg for younger and older patients, respectively; annual prophylaxis dose was 4984 (3679; 6529) and 4089 (3283; 5555) IU/kg. Median (Q1; Q3) annualized number of total bleeds was 2.0 (0.2; 4.2) and 1.8 (0.5; 3.0) for younger and older patients, respectively; annualized total bleed rate was 3.0 (0; 6.0) and 0 (0; 6.4) for these patients in the main study. Median (Q1; Q3) annualized total bleeds within 48 hours of prophylaxis infusion was 0.8 (0; 1.7) and 1.0 (0.1; 1.6) in younger and older patients in the extension study. Response was excellent/good in 337/405 bleeds (83.2%); data were missing for 22 (5.4%) bleeds. Most bleeds (93.5%) were mild/moderate and were spontaneous (42.4%) or trauma related (53.6%). One patient experienced a mild treatment-related serious adverse event (transient very low FVIII inhibitor titer concurrent with acute infection and positive immunoglobulin G anticardiolipin) and remained in the extension study. No change in treatment was required, and the patient was clinically well.
Conclusions:
Data from the LEOPOLD Kids extension study show that BAY 81-8973 provides safe and effective long-term prophylaxis in children with severe hemophilia A treated for a median of 4.1 years, confirming safety results observed in the main study.