impressive significantly longer progression-free survival in patients with untreated metastatic NSCLC and PD-L1 expression on at least 50% of tumor cells.Median progression-free survival was 10.3months (95% CI 6.7 to not reached) in the pembrolizumab group versus 6.0months (95% CI, 4.2 to 6.2) in the control group (HR 0.50; 95% CI, 0.37 to 0.68; P<0.001). Results for overall survival are not mature yet, but the estimated rate of overall survival at 6months also favored pembrolizumab. Previous studies 4,5 reported the benefit of immunotherapy in patients who progressed after a first line of chemotherapy. Although promising results are being reported, the response rate of immunotherapy is still sub-optimal, 4-6 this could be explained by underlying mechanisms that are currently under study.Several strategies are under development to improve the published results of immunotherapy, including dual checkpoint blockade with anti-CTLA-4 antibodies and combination with cytotoxic chemotherapy or anti-VEGF antibodies.