To further evaluate the selectivity and cytotoxicity of Tandyukisin across a range of cancer cell lines, we expanded our analysis beyond the EGFR-amplified breast cancer cell line MCF-7 to include high EGFR-expressing cancer cells (A549, A431, H1299) and low EGFR-expressing cancer cells (HL-60), as well as the non-tumorigenic epithelial cell line MCF-10A. The gene discussed is EGFR; the disease is breast cancer.