1320_PR: Subgroup analyses of patients with epidermal growth factor receptor (EGFR)-expressing tumors in SQUIRE: A randomized, multicenter, open-label, phase III study of gemcitabine–cisplatin (GC) plus necitumumab (N) versus GC alone in the first-line treatment of patients (pts) with stage IV squamous non-small cell lung cancer (sq-NSCLC)