Biosimilars: Extrapolating the evidence. A roundtable discussion

Abstract

Biological anticancer therapies developed in recent decades have contributed to improvements in patient care for serious illnesses. Patents for several biologics will soon expire, paving the way for initiating approval processes for biosimilars—defined as highly similar versions of already licensed or approved biological therapies. The aim of developing a biosimilar is to establish similarity in terms of quality, safety, and efficacy rather than to reestablish clinical benefit. Fundamentally if two products are highly similar, all aspects of their therapeutic effects (ie, safety, immunogenicity, and efficacy) should also be highly similar. This introduces a different way of thinking about drug development for clinicians, who will ultimately analyze and integrate biosimilars into existing treatment paradigms. As such, oncologists across specialties need to understand the core concepts of biosimilarity, including extrapolation—the approval of a biosimilar for use in an indication held by the previously approved biological therapy (deemed the reference product), but not directly studied in a comparative clinical trial with the biosimilar. Extrapolation is the highly scrutinized scientific rationale that bridges data collected across indications and has important implications in oncology, where biological anticancer therapies are currently licensed for use across tumor types and in supportive care. In this roundtable discussion, experts specializing in breast, lung, hematologic, and gynecologic cancers highlight the scientific and clinical rationale behind establishment of biosimilarity and extrapolation. They provide practical insight into the implications of biosimilars for clinical practices, including their potential to expand global access to important medicines for patients and clinicians.