Biosimilars are highly similar versions of approved branded biologics. Unlike generics, they are not exact replicas of reference products. Minor differences between biosimilars and reference products in some aspects are expected; likewise, biosimilar products will differ from each other. The objective of this review is to discuss the challenges associated with the development and approval of biosimilar products that are unique because of their complex structure and specialized manufacturing processes, which can impact not only efficacy but also immunogenicity and safety. Regulatory guidelines recommend a totality-of-evidence approach focused on stepwise development that involves demonstration of structural similarity and functional equivalence. Structural and functional characteristics of the proposed biosimilar are compared with the reference product; similarity of these functions forms the foundation of the biosimilar development program, including potential animal studies, a human pharmacokinetics/pharmacodynamics equivalence study, and a clinical study to confirm similar efficacy, safety, and immunogenicity. The clinical study should be performed in a sensitive population using appropriate endpoints to allow detection of any clinically meaningful differences between the biosimilar and the reference product if such differences exist. In conclusion, development of biosimilars is focused on the minimization of potential differences between the proposed biosimilar and reference product and the establishment of a robust manufacturing process to consistently produce a high-quality biosimilar product.

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ABP 501 [United States: AMJEVITA™ (adalimumab-atto); European Union: AMGEVITA® (adalimumab)] is the first approved biosimilar to adalimumab [reference product (RP)], a monoclonal antibody (mAb) targeting tumor necrosis factor-alfa (TNF-α). ABP 501 has received approval for use in indications that adalimumab RP is approved for, except those protected by regulatory exclusivity. A systematic step-wise totality of evidence (TOE) approach formed the basis of approval of ABP 501; this involved methodical accumulation of scientifically robust comparative data supporting similarity in analytical, preclinical, and clinical [pharmacokinetics (PK)], efficacy, safety and immunogenicity) evaluations. As a foundational first step, comprehensive analytical assessments demonstrated that ABP 501 is structurally and functionally similar to adalimumab RP in critical quality attributes. Preclinical assessments confirmed similar activity in assessing mechanisms of action and toxicology. Clinical evaluation included a phase 1 PK equivalence study in healthy subjects and two comparative phase 3 studies that evaluated ABP 501 and adalimumab RP in two sensitive patient populations, plaque psoriasis (PsO) and rheumatoid arthritis (RA). The PK profiles of ABP 501 and adalimumab RP were similar in healthy subjects as well as patients with PsO and RA. The pivotal phase 3 study in patients with PsO demonstrated that ABP 501 was clinically similar to adalimumab RP in terms of efficacy, safety and immunogenicity in both the primary and transition phases. The pivotal phase 3 study in patients with RA also established clinical similarity between ABP 501 and adalimumab RP; an open-label extension of this study demonstrated sustained efficacy over an additional 72 weeks, with no new safety or immunogenicity concerns with ABP 501 treatment. Overall, the TOE supported the conclusion that ABP 501 is highly similar to adalimumab RP and provided scientific justification for extrapolation to all the approved indications of adalimumab RP not protected by exclusivities.Funding: Amgen Inc.

Biologic drugs approved via the abbreviated United States biosimilar approval pathway are anticipated to improve access to medications by addressing increasing health care expenditures. Surveys of health care practitioners indicate that there is inadequate knowledge and understanding about biosimilars; this must be addressed to ensure safe and effective use of this new category of products. Concepts of biosimilar development, manufacturing, regulation, naming, formulary, and inventory considerations, as well as patient and provider education should be included within the doctor of pharmacy (PharmD) curriculum as preparation for clinical practice. Based on these considerations, we propose that PharmD graduates be required to have knowledge in the following domains regarding biologics and biosimilars: legal definition, development and regulation, state pharmacy practice laws, and pharmacy practice management. We link these general biosimilar concepts to the Accreditation Council for Pharmacy Education (ACPE) Standards 2016 and Center for the Advancement of Pharmacy Education (CAPE) Outcomes 2013, and provide example classroom learning objectives, in-class activities, and assessments to guide implementation.