EGFR and colonic neoplasm: The cytotoxic activity of compounds 1–5 was evaluated in vitro, disclosing a strong proliferation-reducing effect of compound 4 in the HT-29 human colon cancer cell line, which was employed as a preclinical model to study refractory mCRCs that are resistant to anti-EGFR therapies, as well as other chemotherapeutic drugs currently used in the clinical setting.