Assays used to assess biosimilarity of therapies for inflammatory bowel disease.

: Biological drugs have revolutionized the treatment of various medical conditions. Recently, upon expiration of patents of a few biological agents, biosimilars are being rapidly developed as an affordable substitute for more expensive biologic drugs, which may serve as a therapeutic alternative for biologics reference medical product (RMP). Prior to approval for use of the biosimilar drug for treatment of RMP indications, a process involving several different assays is required, in which the biosimilar must prove to posses no meaningful differences from an existing approved RMP in terms of purity, safety and potency.: This report describes the different assays which are used to assess biosimilar drugs using CT-P13 infliximab biosimilar as a case-in-point. It covers the assays of physicochemical characterization, biological activity, and immunogenicity and examines their rational along with methodological and conceptual caveats clinicians should be cognizant of.: The approval of a biosimilar is a complex process that requires several assays, specifically tailored to the characteristics of the RMP. Determining the required assays and the allowable margin of confidence are of great importance but are not sufficient in order to prove that the biosimilar is indeed not inferior in its clinical potency and safety to the RMP.