Metastatic breast cancer patients in the European Union will have the possibility of being treated with a biosimilar of Avastin (bevacizumab), following the approval of Pfizer’s Zirabev (bevacizumab) as a more affordable treatment with similar efficacy to the original. Zirabev is the second biosimilar to Avastin approved by the European Commission and covers its use in five indications in the original treatment's label, including in combination with the chemotherapy Taxol (paclitaxel) for the first-line treatment of breast cancer patients with metastatic disease. Biosimilars are biological medical products that are nearly identical to an original product, but manufactured by a different company after the original product’s patent expires. They usually are sold at significantly lower prices. Unlike chemical compounds, which are made through chemical reactions, biological medicines are grown in cells and may show some differences from similarly designed products. As a result, regulatory agencies require extensive data showing that a biosimilar has equivalent safety and effectiveness, and behaves similarly in the body in regard to absorption, distribution, metabolism, and excretion, to the original medicine. Avastin is an antibody that targets the VEGF molecule, which helps cancers grow blood vessels so they receive enough nutrients and oxygen to survive and thrive. It is approved for 10 indications, including colon, breast, lung, kidney, ovarian, and cervical cancers. But its patent will expire in the U.S. in July 2019 and in Europe in January 2022, and cheaper options are now emerging.