Abstract.Lung cancer is the most common cancer and remains the leading cause of cancer-related deaths worldwide. In total, 85% of lung cancer cases are non-small cell lung cancer, (NSCLC) and 15% are small cell lung cancers (SCLC). More than half of patients who were diagnosed with NSCLC at an advanced stage have an extremely poor prognosis; median overall survival is less than 12 months and 5-year survival is less than 1% despite advances in chemotherapy (1, 2).NSCLC encompasses the pathologically distinct adenocarcinoma, squamous cell carcinoma, and large cell carcinoma sub-types. Approximately 45% and 40% of patients with NSCLC are positive for epidermal growth factor receptor (EGFR) exon 19 deletions and exon 21 L858R mutations, respectively (3, 4). These mutations are predictive of treatment benefit from small molecule EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib, gefitinib, and afatinib. In addition, such sensitizing EGFR mutations occur in approximately 10% of Caucasian patients and more than 50% of Asian patients with NSCLC (5). However, most patients develop resistance to these small-molecule EGFR TKIs after the first 8 to 16 months (6). T790M in EGFR is an acquired resistance mutation in 60-70% of patients who initially respond to prior treatment with small-molecule EGFR TKIs (6). On the basis of these lines of evidence, the development of molecularlytargeted therapies is required to ameliorate the clinical prognosis in NSCLC with T790M mutation.Heparin-binding EGF-like growth factor (HB-EGF) is an EGFR ligand (7-9), and is initially synthesized as a transmembrane protein, similarly to other members of the EGF family of growth factors (7-9) Previously, we reported that RNA interference of proHB-EGF (HBEGF) gene, or the addition of cross-reacting material 197 (CRM197), a specific HB-EGF inhibitor, resulted in significant apoptosis of cancer cells harboring HB-EGF expression, indicating that HB-EGF could be a valid target for cancer therapy in ovarian, breast, bladder, and gastric cancer, among others 3825