Dr. Gralow on the Science of Biosimilars and Implementation in Breast Cancer

Julie R. Gralow, MD, clinical director, Breast Medical Oncology, Seattle Cancer Care Alliance, professor, medical oncology, University of Washington School of Medicine, discusses the science of biosimilars and their implementation in breast cancer.

Biosimilars are a relatively new class of agents, especially in the United States, explains Gralow. In other parts of the world, especially in Europe, biosimilars have been in use for a while. Meanwhile, in the United States, a biosimilar specific to breast cancer was introduced to clinics in December 2019. Though 5 trastuzumab (Herceptin) biosimilars have been approved by the FDA over the past few years, none of them have been used in clinics until recently.

Biosimilars are not generics; rather, they are similar to a biologic because they are not 100% identical to the original drug. The manufacturing process does not allow for control over all aspects in every batch and molecule. There is a process behind how these biologics get approved by the FDA, Gralow explains. The biosimilars are compared with the original drug and must show no obvious differences in purity, safety, or efficacy. If the biosimilar is FDA approved, they have gone through processes to ensure they are as similar as possible to the original drug, concludes Gralow.