Coevolution of NK and Tumor Cell States Along Multiple Myeloma Progression from Precursor Conditions

Multiple myeloma (MM) develops through asymptomatic precursor stages characterized by progressive remodeling of the bone marrow (BM) immune microenvironment and disruption of bone homeostasis. To delineate changes in natural killer (NK) cell states during disease evolution, we investigated coordinated immune-tumor remodeling by integrating NK cell functional states with plasma cell-intrinsic susceptibility programs derived from CRISPR-based screens across healthy donors (HD), monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM), and newly diagnosed MM patients. The integration of NK cell state-associated gene signatures with plasma cell transcriptional programs revealed stage-specific co-variation between immune and tumor compartments. Public single-cell RNA sequencing datasets were interrogated to resolve NK cell heterogeneity, identifying cytotoxic CD56dim and regulatory CD56bright subsets. NK cell dynamics displayed stage-dependent changes, with early expansion followed by the contraction of CD56dim cells in BM, whereas CD56bright cells showed predominantly compositional remodeling. Within the CD56bright subset, transcriptional changes included an increased expression of KLRC1 (encoding NKG2A), subsequently validated by multiparametric flow cytometry. In parallel, plasma cell programs associated with NK sensitivity progressively decreased along disease stages, supporting tumor adaptation to immune pressure. The NKG2A ligand HLA-E displayed selective expression within CD16+ monocytes and followed a distinct variable pattern across disease stages, highlighting a microenvironmental contribution to NK cell regulation. Collectively, these findings indicate a coordinated process of immune-tumor co-evolution, characterized by dynamic remodeling of NK cell states and plasma cell susceptibility, with the NKG2A–HLA-E axis emerging as a central interface during MM progression.