Differentiating biosimilarity and comparability in biotherapeutics

The manufacture of biologics is a complex process involving numerous steps. Over time, differences may arise as a result of planned changes to the manufacturing processes of a biologic from the same manufacturer. Comparability is the regulatory process that outlines the scope of an assessment required of an already licensed biologic after a manufacturing process change made by the same manufacturer. The aim of a comparability assessment is to demonstrate that any pre-manufacturing and post-manufacturing changes have no adverse impact on quality, safety, and efficacy of the biologic. A comparability assessment is distinct from a biosimilarity assessment, which involves extensive assessment of a biologic that is highly similar to the originator (reference product) in terms of quality, safety, and efficacy. The US Food and Drug Administration, European Medicines Agency, and World Health Organization have applied the fundamental comparability concepts into their respective biosimilarity guidance documents. In this review, we examine the rationale behind the distinct, highly regulated approval processes governing changes that may occur over time to an originator biologic due to planned manufacturing changes (as described by a comparability exercise) and those that outline the approval of a proposed biosimilar drug, based on its relationship with the reference product (biosimilarity evaluations).