The cytotoxic activity against breast cancer cell lines was then explained using molecular docking simulation, which revealed that the sesterterpenoid derivatives phorbaketal A acetate (12) and secoepoxyansellone A (13) in combination with mycalol-522 (17) had the best binding energy with the Epidermal Growth Factor Receptor tyrosine kinase (EGFR). This evidence concerns the gene EGFR and breast cancer.