Figure 5.

SE‐NK/T‐DM1 cells exert strong anticancer effects against the target cancer cells through combined cytotoxic activities of all components. Effects of T‐DM1 on cancer cell death. The targeted anticancer activity of antibody and chemotherapeutic agents was demonstrated by comparing the cytolytic effects of TZ and T‐DM1, TZ+NK cotreatment and T‐DM1+NK cotreatment, and SE‐NK/TZ cells and SE‐NK/T‐DM1 cells against a) SK‐BR‐3 cells or b) MDA‐MB‐231 cells. Cancer cells labeled with CMAC (blue) were coincubated with each treatment. Unbound immune cells were removed after 2 h and the remaining cell mixtures were incubated for additional 24 h. T‐DM1 induced greater cancer cell death compared to TZ due to the DM1 conjugation. Likewise, SE‐NK/T‐DM1 cells showed enhanced anticancer activity compared to SE‐NK/TZ cells. Surface‐engineered antibody or ADCs on NK cells induced greater cytotoxicity against the target cancer cells compared to unmodified NK cells or corresponding cotreatments. In MDA‐MB‐231 cells, only the nonspecific activity of NK cells was observed. c,d) Identification of the anticancer activity of NK cells. Experimental approach described for (a) and (c) was followed with an inclusion of Jurkat (JK) cells, a surrogate negative T‐cell line. The cancer cell death induced by SE‐NK/T‐DM1 cells was compared to that of SE‐JK/T‐DM1 cells against c) SK‐BR‐3 cells and d) MDA‐MB‐231 cells. JK showed significantly lower cytotoxicity compared to NK cells. SE‐JK/T‐DM1 cells only displayed the anticancer activity of T‐DM1 and SE‐NK/T‐DM1 cells showed superior anticancer activity over all treatment. Cancer cell death was measured with flow cytometry using an annexin V Alexa Fluor 488 and propidium iodide kit. Data represent mean ± SD (ns, not significant, **P < 0.01, ****P < 0.0001, by one‐way ANOVA followed by Tukey post hoc tests).