Inspired by the high accumulation efficacy of Tet-HER1-CAR-T cells in the lungs, which are the primary site for both primary lung cancer and secondary metastatic tumors (e.g. TNBC), we investigated the tumor-suppression effect of Doxy@CaCO3-PEG-activated Tet-HER1-CAR-T-cell therapy in NCI-H23 lung tumor metastasis-bearing nude mice. Here, EGFR is linked to lung cancer.