This is an open-label, multicenter, randomized, phase II clinical trial, which aims to evaluate the effectiveness and safety of gefitinib versus combination of gefitinib and doublet chemotherapy or apatinib in advanced non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) activating mutation (exon 19 deletion or exon 21 L858R point mutation), accompanied with Bim deletion or low activating EGFR mutation abundance.