Girentuximab (development code cG250) is an investigational, chimeric monoclonal IgG1 antibody developed for the diagnosis and treatment of clear cell renal cell carcinoma (ccRCC). It functions as a targeted agent against a specific carbonic anhydrase isoform. Girentuximab binds with high affinity to its target antigen, which is highly expressed on the surface of ccRCC cells. For therapeutic purposes, it has been investigated in radiolabeled forms (e.g., with lutetium-177 or iodine-131) as a radioimmunotherapy (RIT), delivering localized radiation directly to the tumor. It has also been studied as an unlabeled ("naked") antibody to engage immune effector mechanisms like antibody-dependent cellular cytotoxicity (ADCC).