A total of four EGFR TKIs (gefitinib, erlotinib, lapatinib, and afatinib) are currently in clinical use, with gefitinib, erlotinib, and afatinib being employed to treat lung cancer, while lapatinib (which inhibits both EGFR and Her2) is used for breast cancer. The gene discussed is EGFR; the disease is lung cancer.