FIGURE 1.

Nimotuzumab induces natural killer (NK) cell-mediated ADCC on EGFR+ tumor cells. (A) Isolated NK cells from healthy donors were co-cultured at different ratios E: T 20:1, 10:1, and 5:1 for 4 h with ⁵¹Cr-labeled JHU029 HNSCC cells coated with panitumumab (10 ug/mL), cetuximab (10 ug/mL) or nimotuzumab (10ug/mL), IgG1 and IgG2 were used as negative controls. Incubation with cetuximab or nimotuzumab demonstrated similar level of specific lysis on tumor cells when compared with either untreated or isotype control (^∗∗∗p < 0.001), while panitumumab did not induce a significant lysis (p > 0.05). Graph shows a representative experiment of a triplicate (Two-tailed ANOVA). (B) CD16 expression on NK cells was downregulated after nimotuzumab or cetuximab-mediated ADCC (^∗∗p < 0.01). Expression levels of CD16 [represented in mean fluorescence intensity (MFI)] on NK cells co-cultured with PCI-15B (1:1 ratio), conditions were: untreated, cetuximab, nimotuzumab, panitumumab (all at 10 ug/mL, 24 h) were measured. Data are representative of three experiments from 10 different donors. A two-tailed unpaired t-test was conducted for statistical analysis.