Daiichi Sankyo was established by the merger of Daiichi Pharmaceuticals and Sankyo in 2005. As of 2023, approximately one third of revenue comes from its Japan businesses, which will shrink in the future as the company expands its global footprint. Its primary growth driver is its leading platform of antibody drug conjugates, or ADCs. Its three lead ADCs are Enhertu (HER2), Dato-DXd (TROP2), I-DXd (B7-H3), HER3-DXd (HER3), and R-DXd (CDH6). Enhertu entered the clinic in 2015 and received its first US approval in December 2019 for third-line late-stage HER2-positive breast cancer. It is also approved for HER2-positive stomach cancers and HER2 mutant non-small cell lung cancer.