Potential Treatment for Multiple Myeloma: Immune Checkpoint Inhibitors

Multiple myeloma (MM) is a malignant disease in which monoclonal plasma cells proliferate abnormally. The poor prognosis of MM is always closely related to the immunosuppression of T cells. Restore the immune function of suppressed T cells may reverse the immunodeficiency in the MM microenvironment and improve prognosis. In recent years, immunosuppressive receptors such as programmed cell death receptor-1 (PD-1), T cells immunoglobulin and ITIM domain (TIGIT), Lymphocyte-Activation Gene-3 (LAG-3), T cell immunoglobulin and mucin domain–containing molecule 3 (Tim-3), Leukocyte immunoglobulin-like receptor B1 (LILRB1) and Cytotoxic T- lymphocyte antigen 4 (CTLA-4) have been discovered playing a key role in the tumor immunodeficiency microenvironment. For patients with solid tumors and some leukemia, immunotherapy targeting such receptors can significantly improve the T cells immunodeficiency. However, similar positive results were not found in MM patients, which is related to the complex immunosuppressive mechanism. At present, the understanding of immunosuppressive receptors in MM is insufficient. In this review, this paper summarized part of the studies on PD-1, TCLA-4, Tim-3, TIGIT and other popular immunosuppressive receptors in MM, in order to attract more attention, and in-depth research on the immunotherapy also to promote the immunotherapy of MM from basic research to clinical transformation as soon as possible.