EGFR and lung cancer: Lung cancer is a key example in targeted therapy approaches, since patients with non-small-cell lung cancer (NSCLC) harbouring activating mutations in the EGFR gene demonstrate a significant progression-free survival benefit when treated with EGFR tyrosine kinase inhibitors (TKIs).63 However, the majority of patients that are initially responding will develop acquired resistance after 12–24 months of treatment.