TAS-120 is primarily used in the treatment of advanced or metastatic solid tumors, particularly those with fibroblast growth factor receptor (FGFR) genetic alterations. It functions as an FGFR inhibitor, targeting and blocking the activity of FGFRs, which are often implicated in the growth and survival of cancer cells. This makes it a promising therapeutic option for cancers such as cholangiocarcinoma, bladder cancer, and other malignancies driven by FGFR abnormalities. By inhibiting FGFR signaling pathways, TAS-120 helps to slow tumor progression and improve patient outcomes in specific cancer types. Clinical trials have demonstrated its efficacy in patients with FGFR-altered tumors, offering a targeted approach where traditional therapies may have limited effectiveness.