Key design considerations on comparative clinical efficacy studies for biosimilars: adalimumab as an example

The global development of a biosimilar product is a methodologically complex affair, lined with potential design pitfalls and operational missteps to be avoided. Without careful attention to experimental design and meticulous execution, a development programme may fail to demonstrate equivalence, as would be anticipated for a biosimilar product, and not receive regulatory approval based on current guidance. In order to demonstrate similarity of a biosimilar product versus the originator (ie, the branded product), based on regulatory guidance, a stepwise approach is usually taken, starting with a comprehensive structural and functional characterisation of the new biological moiety. Given the sequential nature of the review process, the extent and nature of the non-clinical in vivo studies and the clinical studies to be performed depend on the level of evidence obtained in these previous step(s). A clinical efficacy trial is often required to further demonstrate biosimilarity of the two products (biosimilar vs branded) in terms of comparative safety and effectiveness. Owing to the focus on demonstrating biosimilarity and not safety and efficacy de novo, designing an adequate phase III (potentially pivotal) clinical efficacy study of a biosimilar may present some unique challenges. Using adalimumab as an example, we highlight design elements that may deserve special attention.