Desialylation in combination with Daratumumab treatment enhances NK cell–mediated clearance of MM cells. (A) H929 and JJN3 were treated with DMSO alone (black), DMSO + Dara (gray), SIA alone (orange), and SIA + Dara (red) and were subsequently cocultured with expanded primary NK cells at a 1:1 E:T ratio. (B) JJN3 MM cells were treated with SIA alone (black), all-trans retinoic acid (ATRA) alone (blue), and SIA + ATRA (green) for 72 hours, after which CD38 expression was measured. (C) JJN3 were treated with DMSO alone (black), SIA alone (red), ATRA alone (blue), and SIA + ATRA (green) for 72 hours prior to Dara treatment and coculture with expanded primary NK cells at a 1:1 E:T ratio. Bar graphs represent mean specific lysis + SEM or CD38 MFI + SEM. Data analyzed using one-way ANOVA. n = 5 (A-C); n = 6 (B). *P < .05; **P < .01; ****P < .0001; ns, not significant.