CD274 and Miyoshi myopathy: The expression profile of PD-L1/PD-1 axis in MM has been investigated by numerous research groups; however, the use of mAbs blocking this pathway is still under discussion, at least in part, because of discordant data on PD-L1/PD-1 distribution on malignant plasmacells (PCs) or immune effector cells within the BM microenvironment.