Despite positive safety and quality of life results for FEIBA, the emergency of Hemlibra created difficulties for the FEIBA study and resulted in it being halted.
Results of a safety and quality of life study for the hemophilia A and B inhibitor bypassing agent aPCC, FEIBA(activated prothrombin complex concentrate, factor VIII inhibitor bypass activity) were positive, but the emergence of a competing agent made it difficult to complete the study, investigators noted.
FEIBA is a Takeda product that was initially approved by the FDA in 1986. It is intended for patients who have developed inhibitors to clotting factor products and is approved for prophylaxis as well as on-demand care for severe bleeding episodes.
FEIBA contains many proteins involved in blood clotting that work around inactivation of factors VIII or IX caused by inhibitors.
In FEIBA GO, patients received prophylaxis (n = 37) or on-demand (n = 13) therapy, and the mean annualized bleeding rate was 6.82 and 10.94, respectively.
Investigators said two serious adverse events (AEs) in one patient were possibly related to treatment with FEIBA (acute myocardial infarction caused by coronary artery embolism), but no AEs resulted in death.
“This study demonstrated the long-term real-world effectiveness and consistent safety profile of [FEIBA] as on demand therapy and prophylactic treatment in patients with hemophilia and [high titer] inhibitors,” investigators reported.
However, they terminated the study early due to difficulties enrolling the target number of patients and described low enrollment as one of the key limitations of the study.
Enrollment began in September 2014 and was completed in December 2017. It was in 2018 that Hemlibra (emicizumab) became available for patients with hemophilia A with inhibitors, and in this cohort it cut the bleeding rate by 87%, according to results of the HAVEN-1 trial. It was also less costly than FEIBA: roughly $450,000 per year versus $800,000.
Investigators in the FEIBA GO study indicated it was difficult to conduct more than 48 months of follow-up with patients and speculated it was partly because patients were switching to Hemlibra.
“Difficulties in maintaining regular follow-up visits, especially if patients had moved from pediatric to adult centers or switched between centers during the study duration, also contributed to the high discontinuation rate,” investigators wrote.
In its first full year on the global market, Hemlibra notched $254 million in sales. In 2021, the drug pulled in almost $2.8 billion in sales, Roche reported.
By contrast, FEIBA sales have been on a downtrend, descending to roughly $269 million in 2021 from $1.36 billion in 2016.
When Hemlibra debuted, the Institute for Clinical and Economic Review described its $450,000 annual cost as not only cost effective but also reducing the annual health care budget for patients with hemophilia A by $720,000 for children under 12 and $1.85 million a year for older patients.
Investigators in the FEIBA GO study concluded, however, there is still a role for FEIBA. “Bypassing agents remain an important therapeutic option for the treatment of patients with hemophilia A and high-responding inhibitors, particularly in countries where emicizumab is not available. It is also important to acknowledge that emicizumab is not indicated for the treatment of patients with hemophilia B,” they wrote.