Pemigatinib is primarily used in the treatment of certain types of cancer, particularly cholangiocarcinoma, which is a rare form of bile duct cancer. It is specifically prescribed for patients whose cancer has a specific genetic mutation known as FGFR2 fusion or rearrangement. This medication works by inhibiting the activity of fibroblast growth factor receptors (FGFRs), which play a role in the growth and spread of cancer cells. By targeting these receptors, pemigatinib helps to slow down or stop the progression of the disease. It is typically used when the cancer is advanced or has spread to other parts of the body and cannot be surgically removed. Pemigatinib is taken orally, usually once daily, and its use is often monitored through regular medical check-ups to assess its effectiveness and manage any potential side effects.