In EGFR-mutant advanced NSCLC, immune checkpoint inhibitors do not improve OS over that with docetaxel. Mechanisms of acquired resistance to first-line tyrosine kinase inhibitor therapy should be elucidated to guide selection of second-line treatment for these patients.

Checkpoint inhibitors, compared with docetaxel, are associated with significantly prolong overall survival in second-line therapy in NSCLC. The finding of no overall survival benefit for patients with EGFR mutant tumors suggests that checkpoint inhibitors should be considered only after other effective therapies have been exhausted. The findings of this meta-analysis could also assist in the design and interpretation of future trials and in economic analyses.

In checkpoint-inhibitor trials, ORR correlated poorly with OS. For future phase 2 studies, 6-month PFS rate is recommended as an end point.

Background PD-L1 expression (PD-L1) on tumor cells with or without immune cells is widely reported in clinical trials of PD-1 blockade in metastatic non-small cell lung cancer (NSCLC). Various cutpoints have been studied. Methods We performed a systematic search of MEDLINE, EMBASE and conference proceedings up to December 2019 for randomized and non-randomized clinical trials of anti-PD-1 or anti-PD-L1 monotherapy in metastatic NSCLC. We retrieved data on objective response rate (ORR), 1 year (1yr PFS) and 2 year progression-free survival (2yr PFS), and 2 year (2yr OS) and 3 year overall survival (3yr OS) in various PD-L1 subgroups. Results were pooled and analysed based on different cutpoints, with non-randomized comparisons made to pooled chemotherapy outcomes. Results 9,810 patients in twenty-seven studies were included. In treatment-naïve patients, benefits with PD-1 blockade over chemotherapy were seen in ORR in patients having PD-L1 ≥50%, in 2yr OS for PDL1 ≥1%, and in 1yr PFS, 2yr PFS and 3yr OS for unselected patients. First-line PD-1 blockade compared to chemotherapy demonstrated higher ORR, 2yr PFS and 3yr OS if PD-L1 ≥50%; lower ORR, higher 2yr PFS and similar 3yr OS if PD-L1 1-49%; and lower ORR, similar 1yr PFS and lower 2yr OS if PD-L1 <1%. In previously treated patients, PD-1 blockade demonstrated similar or superior outcomes to chemotherapy in all PD-L1 subgroups. Conclusions PD-L1 should guide the choice of PD-1 blockade versus chemotherapy in treatment-naïve patients. In previously treated patients, PD-1 blockade provides a favourable outcome profile to chemotherapy in all PD-L1 subgroups.

CI inhibitors have different toxicity profiles to chemotherapy. These findings are useful for patient counselling and planning of future trials.