Biosimilars of Hemophilia Therapies: Are They Likely?

Hemophilia A, a genetic clotting disorder, affects approximately 20,000 people in the United States. Treatment of hemophilia was revolutionized by the development of coagulation factor concentrates. The concentrates, which are derived from the pooled plasma of thousands of donors, had significant therapeutic benefits for both the treatment and prevention of bleeds.

However, these treatment options are also extremely expensive. In terms of drug costs, according to pharmacy benefit manager Express Scripts in a 2017 report, Super Spending: US Trends in High-Cost Medication Use, patients who had hemophilia paid some of the highest medication costs reported among members; some hemophilia patients’ drug costs hit $500,000 per year or more.

In a recently published editorial in The Official Journal of the World Federation of Hemophilia,¹ author Angela Thomas, MB, PhD, discusses the advancements in hemophilia treatment as well as the place biosimilars may or may not have in reducing the cost of care.

Because hemophilia is such a rare disorder, from a regulatory perspective, the drugs that treat such diseases are considered “orphan drugs,” earning this distinction due to the fact that fewer than 5 per every 10,000 people are affected. Other factor deficiencies in hemophilia, such as factor VII and factor XIII deficiencies, are rarer still. Yet according to the editorial, there is a widening range of treatments for hemophilia A and B including factor replacements both plasma-derived and recombinant. Drugs being introduced now include products with an extended half-life, while non-replacement products such as monoclonal antibodies, small molecules, and gene therapies are in development.

Currently, there are no biosimilar medicines licensed for the treatment of hemophilia. Due to hemophilia being such a rare disease, the patient population is limited with trials for new therapies competing for recruitment. Thomas notes that licensure pathways that reduce the number of patients required for clinical trials would be beneficial for biosimilars of drugs to treat these population.

In addition, the most serious problem in creating biosimilars that treat hemophilia is the safety issue of immunogenicity and the production of neutralizing antibodies. “Immunogenicity cannot be addressed in animal models, and potentially relevant differences in immunogenicity between 2 products in a biosimilarity exercise will thus not be detected in non-clinical studies; this can only be addressed in clinical trials,” said Thomas.

While the editorial notes that there may be advantages in developing biosimilar medicines for some of the newer modified products or non-replacement products for hemophilia A and B or for recombinant factor XIII, due to market exclusivity, this innovation remains years away.

“For standard factor VII and IX concentrates, the advantages of biosimilars are not clear. There are already a significant number of factor concentrates on the market, and the field of factor replacement therapy is constantly developing with next-generation products and ‘biobetters’ replacing the older factor concentrates rather than development of biosimilar products for such concentrates,” writes Thomas, adding that “…of course, the question ‘what is the risk of inhibitor development with any new product?’ is unlikely to be answered through the development of biosimilar medicines in hemophilia.”

The field of new products includes the recently approved emicizumab-kxwh (Hemlibra). In November 2017, Genentech received FDA approval for the biologic, a once-weekly subcutaneous prophylaxis for adults, adolescents, and children with hemophilia A who have factor VIII inhibitors. A a recent ICER report found that, despite the high price of treatment, the new biologic was still able to cut drug costs in treating hemophila.

Reference

1. Thomas AE. Biosimilars and hemophilia. Haemophilia. 2018;24(1):17-19. doi: 10.1111/hae.13380. Published on January 18, 2018. Accessed on February 27, 2018.