Natural killer (NK) cells are important effector cells in antibody-based immune therapies for multiple myeloma (MM) through antibody-dependent cellular cytotoxicity. Here, we used single-cell transcriptomics, flow cytometry and functional assays to investigate the bone marrow NK cell compartment of MM patients at diagnosis and during treatment. We show reduced proportion of CD16+ cytotoxic NK cells in a subset of patients at diagnosis, which correlated with decreased cytokine production and …