Source of business for biosimilars in immunology

As of August 2023, there were 40 FDA-approved biosimilar products, including 25 commercially available products and four with interchangeable status.¹ Adoption of biosimilars has continued to grow each year across therapeutic areas, and the increased competition they have generated is driving down average sales price (ASP) for both biosimilars and their reference products.² It is estimated that drug spend in classes with biosimilar competition has been reduced by $21 billion over the last six years, and that number is likely to go up with the best-selling US drug, Humira, facing its own biosimilars since the start of 2023.² Three infliximab biosimilars (Pfizer/Celltrion’s Inflectra, Merck/Samsung Bioepis’ Renflexis, and Amgen’s Avsola) have launched in the US and are all indicated for autoimmune conditions, including inflammatory bowel disease (both ulcerative colitis and Crohn’s disease), where this analysis will focus. A key question remains around whether biologic-naïve (“new”) or biologic-experienced (“switch”) patients drive biosimilar uptake. Complicating matters is the fact that payers may require patients to switch from the reference product to a biosimilar, while a recent survey of gastroenterologists suggests that doctors prefer to keep patients on the reference product if they are having treatment success.¹ In this analysis, the uptake of infliximab biosimilars is examined to provide insights on the source of business for biosimilars in immunological conditions.