Maintenance therapy refers to a paradigm of follow-up with an effective drug after the end of first-line therapy and before disease progression. Erlotinib brings a new opportunity to this paradigm, as the efficacy of first-line chemotherapy no longer improves beyond 4-6 cycles, and therefore highly effective, non-cumulative toxic agents are needed for single-agent maintenance. The SATUEN study is the first large prospective randomized controlled study to explore the association of multiple biomarker status with the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) maintenance therapy. Nearly 900 patients with advanced NSCLC whose disease had not progressed after 4 cycles of first-line chemotherapy were randomized to receive erlotinib maintenance therapy or placebo until disease progression. Patients were predominantly white, male, and smokers and had greater treatment difficulty. The SATURN study showed that erlotinib maintenance treatment reduced the risk of disease progression by a significant 29%. In addition, disease control rate (DCR) was significantly higher with erlotinib maintenance therapy than in the placebo group (60.6% vs. 50.8%). Irrespective of gender, race, pathology type and smoking history, erlotinib maintenance therapy provided benefit, with greater benefit in women, Asian, adenocarcinoma and nonsmoking patients. The SATUEN study demonstrated a definite PFS benefit for patients with a wide range of characteristics during the maintenance phase of treatment, with a 20% to 40% reduction in the risk of disease progression in patients with a variety of characteristics (including squamous cancer, smoking, KRAS mutations, EGFR wild-type, and other previously considered non-dominant EGFR-TKI populations), and an encouraging 90% reduction in risk in those with EGFR mutations. This is encouraging.