However, the role of PD-L1/PD-1 axis in MM is still debated, the clinical outcomes of PD-1/PD-L1 inhibitors alone for MM are not very encouraging, the combination of PD-1/PD-L1 inhibitors with other drugs for multiple myeloma appears to be promising (196, 197). The gene discussed is PDCD1; the disease is plasma cell myeloma.