CTLA4 and metastatic melanoma: For this reason, the various options of targeted and immunological therapies such as antibodies against T-lymphocyte-associated protein 4 (CTLA-4, CD152) and programmed death 1 (PD-1) or its programmed death-ligand 1 (PD-L1) are now preferred as first-line therapies for metastatic melanoma.