A Post-Marketing Surveillance Study of the Safety and Efficiacy of Refacto® (Moroctocog Alfa, B-Domain Deleted Recombinant Factor VIII) (St. Louis-Derived Active Substance in the Treatment and Prevension of Bleeding Episodes in Hemophilia a Patients.
Authors: Feingold Jay M. , Smith Mark P. , Littlewood Richard , Giangrande Paul ,   ReFacto STL Study Group
Published: October 2019

This was an open-label, multicenter, post-marketing surveillance study conducted in Belgium, France, Germany, Italy, Netherlands, New Zealand, Switzerland, and UK. The objectives were to assess the safety and clinical efficacy of ReFacto St Louis-derived active substance (STL) in the treatment and prevention of bleeding episodes in patients with hemophilia A in the usual care setting. 60 patients with moderate to severe hemophilia A (FVIII:C <5%) with no history of FVIII inhibitor were enrolled (58 were previously treated patients and 2 were previously untreated patients). Data on infusions, concomitant medications, adverse events, and inhibitor development were collected from patients at regular intervals. Efficacy for prophylaxis was assessed by the investigator approximately every 3 months until 50 exposure days, 6 months or study termination using the number of breakthrough bleeding episodes and the 3-point scale (excellent, effective, and inadequate). The efficacy of each on-demand treatment administered was assessed using the 4-point scale (excellent, good, moderate, and no response). The investigator and surgeon assessed efficacy of surgical prophylaxis jointly after each surgery using the 4-point scale (excellent, good, moderate, and no response). Factor VIII inhibitor (using local laboratory Bethesda assay) was evaluated at screening, after 10 EDs, after 30 EDs, and at the end of treatment.

The investigator determined all dosing and treatment regimens. In the prophylaxis treatment group, no particular prophylaxis regimen was enforced. A total of 32 patients aged 0–66 years initially received prophylaxis treatment: 10 (31%) patients reported no breakthrough bleeds. A median of 6.25 bleeds per year occurred in all prophylaxis patients. Twenty-nine assessments of the prophylactic treatment final outcome were made: 93% of these assessments were excellent or effective. A total of 28 patients aged 1–71 years initially received on-demand treatment with ReFacto STL. 95.2% of bleeds were resolved with 1 or 2 infusions. The assessment of treatment response was excellent or good in 98% of cases. Seven patients underwent 7 surgical procedures, haemostasis was achieved all cases and ReFacto STL was rated as providing an excellent or good response as the final outcome in each case.

As this was a post-marketing study, safety evaluation was focused on collection of serious AEs and product-related non-serious AEs. One PTP (1/58, 1.7%) developed a high titre inhibitor and 1/58 (1.7%) developed a low titre transient inhibitor. One PUP developed a low titre transient inhibitor (0.4 BU). SAEs included 1 fatal intracranial hemorrhage (considered unrelated to ReFacto), 5 preplanned surgeries, 1 episode of gastroenteritis, and 1 hemorrhage. There were no allergic events. Three patients were withdrawn from treatment for safety reasons (1 patient due to death, 1 PTP due to high titre inhibitor and 1 PTP due to low titre transient inhibitor). The nature and incidence of non-serious AEs did not raise new safety concerns. The majority of AEs were mild or moderate in severity.