CD274 and metastatic melanoma: In fact, a report on patients with metastatic melanoma states that exosomal PD-L1 (and not just total soluble PD-L1, as mentioned above by Oh et al.)predicts treatment response and increases in line with IFN-γ; this is to say that increased IFN-γ (perhaps via chronic activation in the tumor microenvironment) increases exosomal PD-L1, leading to local and systemic suppression of the immune system and increased tumor growth.