Safety and efficacy of biosimilars in oncology.

Biosimilars are considered to be one of the solutions to combat the substantially increasing costs of cancer treatment, and its imminent introduction is expected to expand affordability worldwide. However, biosimilar monoclonal antibodies provide many challenges compared with first-generation biosimilars, growth factors, and hormones, because they have shown only a modest clinical effect, and are often used in combination with other more toxic therapies, making it difficult to design studies that allow appropriate efficacy and safety assessments compared with the original products. The value of comparative clinical trials for showing clinical equivalence of biosimilars that demonstrate a high degree of similarity in physical, chemical, structural, and biological characteristics with the original product is increasingly being questioned, and advances in analytical methods that provide robust non-clinical data might reduce the need for extensive clinical comparisons. In this Series paper, the third of three papers on drug safety in oncology, we review the safety and efficacy of biosimilars in oncology, assessing biosimilar monoclonal antibodies in relation to first-generation biosimilars, the issues surrounding interchangeability and extrapolation of biosimilars to other disease and patient indications, and reassessing the safety approval pathway in light of 10 years worth of biosimilar experience.