FIGURE 3.

Chordoma cell susceptibility to killing by healthy donor NK cells is enhanced by cetuximab (anti-EGFR) and combination treatment with N-803 (IL15 superagonist) and cetuximab. Six chordoma cell lines (UM-Chor1, MUG-CC1, UM-Chor5, JHC7, U-CH1, U-CH2) were used as targets for healthy donor NK cells in ¹¹¹In-release killing assays. A, Cetuximab-mediated ADCC assays were performed by co-incubating chordoma cells with N-601 or isotype control antibody. NK cells were treated with anti-CD-16 antibody where indicated. B, Combination treatment assays were performed by co-incubating chordoma cells with cetuximab or isotype control antibody and treating NK cells with N-803 and/or anti-CD-16 antibody where indicated. All E:T ratios are 20:1. Statistical analyses were done by one-way ANOVA with Tukey's multiple comparisons test. *P d 0.05, **P d 0.01, ***P d 0.001, ****P d 0.0001. Results shown are the means ± SEM of technical triplicate measurements and are representative of three independent experiments.