SB8, an approved bevacizumab biosimilar based on totality of evidence: scientific justification of extrapolation

SB8 is a biosimilar of bevacizumab based on its similarity demonstrated by physicochemical, functional, non-clinical and clinical studies. Supported by the concept of extrapolation, SB8 was authorized and is used in a similar manner across all types of tumors as reference bevacizumab. Furthermore, SB8 offers convenience with prolonged stability compared with reference bevacizumab in diluted form. Although a biosimilar must demonstrate biosimilarity to a reference product with the 'totality of evidence' in a stringent regulatory process for marketing authorization, some concerns remain among healthcare practitioners, particularly about extrapolation. This review summarizes the concepts of the totality of evidence and extrapolation in biosimilar development and the role of bevacizumab biosimilars in the management of metastatic colorectal cancer as an extrapolated indication.