Memory-like natural killer cells facilitate effector functions of daratumumab in multiple myeloma

Natural killer (NK) cells support the anti-myeloma activity of daratumumab via antibody-dependent cellular cytotoxicity (ADCC) in multiple myeloma (MM). However, the different roles of heterogeneous NK cell subpopulations have not been elucidated in MM. Here, we delineate memory-like NK cells in the bone marrow (BM) of newly diagnosed MM (NDMM) patients using single-cell RNA sequencing, and further characterize their distinct immunophenotypic features and functions by multicolor flow cytometry. Memory-like NK cells exert robust daratumumab-mediated effector functions ex vivo, including cytokine production and degranulation, compared to conventional NK cells. The composition of memory-like NK cells in BM determines the daratumumab-mediated ex vivo functional activity of BM NK cells in NDMM patients. Unlike conventional NK cells, sorted memory-like NK cells from the BM of NDMM patients exert substantial cytotoxic activity against myeloma cells in the presence of daratumumab. Our findings indicate that memory-like NK cells are an important mediator of daratumumab-dependent effector functions in MM and support direct future efforts to better predict and improve the clinical efficacy of therapeutic antibodies by selectively employing memory-like NK cells. Overall design: NK cells sorted from 3 MM patients' bone marrow, no replicates