Monoclonal antibody drugs account for a significant proportion of oncology spending in the USA and are associated with high out-of-pocket costs for patients. Biosimilar therapies have the potential to improve access to these specialist oncology drugs, but knowledge gaps may slow their adoption.

The degree of biosimilarity is ultimately determined by regulatory authorities and is based on the totality of evidence, which includes data on molecular and functional characterization, other nonclinical data, and the safety, pharmacokinetic, immunogenicity, and efficacy clinical trial data.

Based on this review of published nonclinical and clinical oncology studies, and as inferred from the conclusions of study authors, proposed biosimilars of bevacizumab, rituximab, and trastuzumab exhibit close similarity to their originators.

However, at present, robust evidence of outcomes for monoclonal antibody biosimilars in cancer, including data from comparative efficacy and safety trials, is not yet widely available in the published literature.