Emerging role of biosimilars: Focus on trastuzumab and metastatic human epidermal growth factor receptor 2-positive breast cancer

Biosimilars are emerging class of medications that are very similar to biologics (in terms of safety and efficacy to the original reference product); but not the same as generic, originating, or reference drugs. The availability and use of biosimilars in oncology landscape are slowly picking, thereby combating financial burden to cancer patients. Breast cancer, with a staggering number of cases recently, has become the most common cancer in females. Human epidermal growth factor receptor-2 (HER2)-positive breast cancer involves the cell-surface protein that causes cell growth and proliferation and is more aggressive than typical breast cancer. The emergence of trastuzumab (first oncogene-targeted therapeutic agent for solid tumours to be clinically available under the brand name Herceptin) has improved the scope for patients suffering from this type of breast cancer. However, the associated cost remains to be a significant barrier for patients with breast cancer to access this treatment. Biosimilars, since their relatively recent advent, have reduced the cost of cancer treatment significantly, and will continue to play important cost-effective therapeutic roles for years to come. Notably, healthcare professionals still bear a somewhat negative/reluctant connotation to biosimilars. This article attempts to describe and analyse the studies that have been published in peer-reviewed literature on the use of trastuzumab biosimilars and their efficacy, safety, pharmacokinetic, and pharmacodynamic properties. It also covers on the chemistry and clinical advantages of using biosimilars for the ongoing and future treatment prospects for patients with breast cancer.