Moreover, the response of patients to TKIs (e.g., Gefitinib) is temporary with little to no longer-term clinical benefits due to tumours developing acquired drug resistance via secondary EGFR mutations or shifting their oncogenic dependence to EGFR-independent oncogenic pathways, including the KRAS/RAF/ERK pathway [31,62,63]. The gene discussed is EGFR; the disease is neoplasm.