Immune microenvironment and immunotherapy resistance in multiple myeloma

Abstract

Multiple myeloma (MM) is currently treated with combined immunotherapies targeting the immune microenvironment surrounding MM cells. Although novel immunotherapeutic agents for MM have improved complete response rates and survival time, some patients experience repeated relapses and die of MM because its progression is strongly influenced by the immune microenvironment as well as cytogenetic abnormalities of MM cells. Various studies have elucidated the mechanisms underlying the immunosuppressive immune microenvironment of MM. Recently, single-cell RNA sequencing and cytometry by time-of-flight analysis have revealed spatiotemporal crosstalk between MM and immune cells in the bone marrow of patients with MM. These studies showed that immunosuppression appears in the early stages of MM and becomes stronger as the disease progresses, leading to immunotherapy resistance. Understanding the state of the immune microenvironment in patients with MM is important for developing immunotherapeutic strategies for long-term complete response and cure.