Figure 5.

Epidermal growth factor receptor (EGFR)‐specific chimeric antigen receptor (CAR)‐engineered natural killer (NK) cells (EGFR‐CAR NK cells) inhibited the tumor growth of triple‐negative breast cancer (TNBC) exhibiting enhanced EGFR expression in the patient‐derived xenotransplant (PDX) mouse model. Immunohistochemical assay assessed estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and EGFR expression in (A) the clinical breast cancer sample and (B) breast tumors of NSG mice. Compared to Con‐CAR NK cells, the EGFR‐CAR‐1 NK cells and EGFR‐CAR‐2 NK cells decreased the (C, D) tumor weight and (E) tumor volume but did not affect the (F) body weight of mice. The error bars represent the mean ± standard error of mean (SEM) (n = 4). t test; **P < .05 and ***P < .01