Biosimilars in oncology: A decade of experience with granulocyte colony-stimulating factor and its implications for monoclonal antibodies.

Biosimilars offer the potential for improved sustainability of cancer care. In oncology, granulocyte colony-stimulating factor and erythropoiesis-stimulating agent biosimilars have been available for almost a decade, with biosimilars of monoclonal antibodies a more recent development. Sandoz biosimilar filgrastim was approved based on Phase III confirmatory studies conducted in patients with breast cancer experiencing chemotherapy-induced neutropenia, with other indications granted based on extrapolation. Despite the fact that extrapolation is a well-established scientific principle in regulation of biological medicines, it is a commonly misunderstood part of the biosimilar concept. Broad experience from almost a decade of use of Sandoz biosimilar filgrastim includes >21 million patient-days exposure and >9 years of real-world clinical evidence, indicates extrapolation successfully at work. Together, this can help reassure oncologists that extrapolation is based on sound scientific principles. Efforts to improve understanding of extrapolation are critical to ensure the acceptance of future oncology biosimilar monoclonal antibodies.