Increased frequency of dysfunctional NK cells in patients with MM correlates with poor clinical outcome. NK cells were analyzed by flow cytometry in thawed BM samples of 177 patients with NDMM from the IFM 2009 clinical trial and 20 HDs. (A) Table showing the clinical features of IFM 2009 patients analyzed in this study. (B) Representative FACS plots and graph comparing NK cell frequency among CD138-depleted BM from HD and patients with MM. (C) Kaplan-Meier survival estimates over >3000 days of follow-up for MM patients with NK^high (more than median value) and NK^low (less than or equal to median value) frequency. (D) Representative FACS plots and graph comparing CD16/CD226^Lo cell frequency among NK cells from patients with MM and HDs. (E) Kaplan-Meier survival estimates over >3000 days of follow-up for MM patients with CD16/CD226^Lo high (more than median value) or low (less than or equal to median value) frequency. (F) Kaplan-Meier survival estimates over >3000 days of follow-up for MM patients with an absolute frequency of NK CD226/CD16^Lo among CD138–depleted BM mononuclear cells split by quartile. (G) Multivariate analysis showing hazard ratio and associated P value of the indicated variables for OS in patients with MM.