MTOR and plasma cell myeloma: AA, antiangiogenics; AR, antiresorptive; BP, bisphosphonate; mAb, monoclonal antibody; MM, multiple myeloma; MRONJ, medication-related osteonecrosis of the jaw; mTOR, mammalian target of rapamycin; PDGF, platelet-derived growth factor; RTX, rituximab; TKI, tyrosine kinase inhibitor; TNF-α, tumor necrosis factor-alpha; VEGF, vascular endothelial growth factor; VEGFR, vascular endothelial growth factor receptor