The IC50 afatinib values for the whole primary NSCLC cell line panel of 4.81 ± 2.05 μM is a typical result for cell lines not dependent on mutated EGFR, such as breast cancer cell lines T47D and BT20, whereas IC50 values for afatinib and cell lines addicted to mutated EGFR may be as low as 6–10 nM [25]. This evidence concerns the gene EGFR and breast cancer.