Bay 81-8973 in the Real World: Clinical Effectiveness and Safety in Patients with Hemophilia Α across the US and Europe

Background: BAY 81-8973 (Kovaltry®, Bayer) is an unmodified full-length recombinant FVIII launched in 2016 in Europe and the US for the prophylaxis and treatment of bleeds in patients with hemophilia A. BAY 81-8973 has been extensively studied in clinical trials, which have demonstrated consistent efficacy and safety in both children and adults in the LEOPOLD trials, and since launch, 6750 patient-years of experience have been accumulated. Pharmacokinetic analyses have demonstrated an increased half-life for BAY 81-8973 compared with standard factor VIII products (rFVIII-FS and rFVIII [rAHF-PFM]). Real world evidence demonstrating the effectiveness and safety of BAY 81-8973 across age groups is being collected, though aggregated international data have yet to be published. The primary objective of this analysis was to describe the effectiveness of BAY 81-8973 in the real world setting in children and adults from Europe and the US, as captured in the Cost of Haemophilia: a Socioeconomic Survey (CHESS) study.

Methods: The CHESS 2018 program investigated the economic and psychological burden of moderate and severe hemophilia (FVIII < 5%) in Europe and the USA. The pediatric cohort (CHESS Pediatric) included 1050 males aged 1-17 years, with moderate or severe hemophilia, while CHESS US included 568 adults with severe hemophilia aged > 18 years. Clinical and patient reported data were obtained via medical chart abstraction and cross-sectional surveys sent to both physicians and patients. Data were collected between December 2017 and April 2018, and captured 12 months of clinical retrospective data. The current study is a descriptive analysis of patients treated with BAY 81-8973 from the CHESS pediatric and adult cohorts.

Results: At the data cut off (May 2018), 49 patients were being treated with BAY 81-8973. The majority of pediatric patients were aged 6-11 years (51.7%, n=15), while 17.2% (n=5) were aged 0-5 years and 31% (n=9) were aged 12-17 years. In the adult US cohort, most (60%, n=12) were aged 18-35 years, 35% (n=7) were aged 36-59 years, and 5% (n=1) were aged > 60 years. The vast majority of patients across cohorts had severe disease (93.1% of children and 100% of adults); however, 89.7% (26/29) of children and 80% (16/20) of adults had no target joints. In this population, 75.9% (22/29) of children and 55.0% (11/20) of adults were receiving regular prophylaxis with BAY 81-8973. Children and adults on prophylaxis both had a mean (± SD) of 2 (± 1) infusions/week, with median (Q1; Q3) weekly doses of 84 (67; 110) and 62 (29; 144) IU/kg, respectively. Overall, 20.7% (6/29) of children and 35% (7/20) of adults treated with BAY 81-8973 had zero bleeds and mean annualized bleed rate (ABR) was 2.66 (± 2.06) in children and 1.45 (± 1) in adults; 68.9% (20/29) of children and 95.0% (19/20) of adults had experienced ≤ 3 bleeds in the previous year. There were no reports of inhibitor development in either the pediatric or adult cohorts while on BAY 81-8973.

Conclusions: These observations suggest that BAY 81-8973 is an effective and well-tolerated treatment for adults and children with moderate and severe hemophilia A, with ABR < 3 in children and < 2 in adults and with many patients free from bleeds despite only 67% of patients studied receiving regular prophylaxis. These data confirm the observations from the LEOPOLD trials, suggest BAY 81-8973 provides good protection from bleeding across a range of patient types in routine clinical practice and illustrate how the established pharmacokinetic profile of BAY 81-8973 translates to clinical benefits for patients with hemophilia A.

Study supported by Bayer