Biosimilars for oncology products and supportive agents have been on the market longer than any other class of biosimilars, with the first being a filgrastim biosimilar approved in 2015. There are now multiple biosimilars for filgrastim, pegfilgrastim, bevacizumab, trastuzumab, and rituximab. Payers have reported a significant decrease in cost per claim of oncology products that have biosimilars since 2019 with decreases in cost per claim between 33% and 39%. While oncology biosimilar uptake was initially slow, biosimilars for bevacizumab, trastuzumab, and rituximab now make up more than 73% of the market share through 2022.