CD274 and metastatic melanoma: Kjeldsen et al. tested an immune-modulatory peptide vaccine (IO102/IO103) against indoleamine 2,3-dioxygenase (IDO) and PD ligand 1 (PD-L1) together with anti-PD-1 inhibitor nivolumab in 30 patients with metastatic melanoma in a non-randomized phase 1⁄2 study (clinical trial MM1636).