SLAMF7 and plasma cell myeloma: To explore the potential use of elotuzumab to enhance the ability of autologous NK cells to eliminate tumor cells that exhibit negative or low CS1 expression levels, we initially assessed the expression levels of CS1 on NK cells, myeloma cell lines (RPMI 8266 and U266), and non-plasma cell tumor cell lines (Nalm-6 and Raji).