CD274 and plasma cell myeloma: Blocking PD‐1/PD‐L1 can reactivate the cytotoxic T‐cell‐mediated killing of tumors, which is an important cancer immunotherapy approach.[19] In addition, melphalan or bortezomib increased the expression of PD‐L1 in primary myeloma cells and myeloma cell lines (Figure 2C,D).