CCR4 antagonists are primarily used in the treatment of certain types of cancer and inflammatory diseases. They work by blocking the CCR4 receptor, which is involved in the migration of immune cells to sites of inflammation or tumors. This inhibition can help reduce the growth and spread of cancer cells, particularly in T-cell lymphomas and other malignancies where CCR4 is overexpressed. Additionally, CCR4 antagonists are being explored for their potential in treating autoimmune diseases and allergic conditions by modulating immune responses and reducing inflammation. Their ability to target specific pathways makes them a promising option for precision medicine approaches.