A single-country, multicenter, prospective cohort study in Greece, the “LUNGFUL” observational study [37], aimed to evaluate the frequency of acquired T790M resistance in late-stage EGFR-mutant NSCLC patients who had received first-generation or second-generation TKIs (erlotinib, gefitinib, and afatinib) and experienced disease progression. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.