Biopharmaceuticals exhibit excellent therapeutic efficacy; however, their high cost remains a significant limitation. The introduction of biosimilars is expected to enhance market competition and reduce biopharmaceutical prices. As of January 2025, Europe has approved 92 biosimilars for 25 reference biopharmaceuticals since the first biosimilar launch in 2006, contributing substantially to price reductions. In contrast, although the US FDA has approved 64 biosimilars for 17 reference products since 2015, their market uptake remains limited, and the resulting price reductions have been minimal. Two primary hypotheses have been proposed to explain this disparity: (1) biosimilar entry is hindered by complex patent landscapes and litigation initiated by originator companies, and (2) structural differences in biosimilar-related regulatory frameworks between the United States and Europe influence market dynamics. In this study, we examine key patent filings and litigation histories for Humira and Remicade, alongside biosimilar sales trends and pricing in both the United States and Europe following expiration of substance patents. Furthermore, by comparing current regulatory frameworks, including approval pathways, prescribing practices, and policies on interchangeability and substitution, we identify factors that have promoted biosimilar adoption in Europe and explore implications for encouraging biosimilar uptake in Korea.