Biologics are important treatments for a number of cancers. Patents for several biologics will expire over the next decade, removing a barrier to the development and commercialization of biosimilars. As biologics differ from small-molecule drugs due to their size and complexity, multifaceted manufacturing process, and their potential for immunogenicity, biosimilars cannot be considered "generic versions" of currently approved biologics. In highly regulated markets, biosimilars can be authorized only if they are demonstrated to be highly similar to the original drug from an analytical and clinical perspective. Any differences must be justified and shown to have no clinically meaningful effect on the safety and efficacy of the biosimilar. The European Medicines Agency has approved a number of biosimilars and the recent approval of the biosimilar infliximab monoclonal antibody is another regulatory milestone. This article will provide context regarding key safety issues addressed in biosimilar development, approval, and delivery, as well as inform oncologists on matters of safety to consider when prescribing biosimilars. Pertinent issues about safety from countries or regions where biosimilars are currently in use also will be reviewed.
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