High expression of PD-L1 was associated with the presence of EGFR mutations in surgically resected NSCLC and was an independent negative prognostic factor for this disease.

Purpose: Therapies targeted to the immune checkpoint mediated by PD-1 and PD-L1 show antitumor activity in a subset of patients with non-small cell lung cancer (NSCLC). We have now examined PD-L1 expression and its regulation in NSCLC positive for the EML4-ALK fusion gene.Experimental Design: The expression of PD-L1 at the protein and mRNA levels in NSCLC cell lines was examined by flow cytometry and by reverse transcription and real-time PCR analysis, respectively. The expression of PD-L1 in 134 surgically resected NSCLC specimens was evaluated by immunohistochemical analysis.Results: The PD-L1 expression level was higher in NSCLC cell lines positive for EML4-ALK than in those negative for the fusion gene. Forced expression of EML4-ALK in Ba/F3 cells markedly increased PD-L1 expression, whereas endogenous PD-L1 expression in EML4-ALK-positive NSCLC cells was attenuated by treatment with the specific ALK inhibitor alectinib or by RNAi with ALK siRNAs. Furthermore, expression of PD-L1 was downregulated by inhibitors of the MEK-ERK and PI3K-AKT signaling pathways in NSCLC cells positive for either EML4-ALK or activating mutations of the EGFR. Finally, the expression level of PD-L1 was positively associated with the presence of EML4-ALK in NSCLC specimens.Conclusions: Our findings that both EML4-ALK and mutant EGFR upregulate PD-L1 by activating PI3K-AKT and MEK-ERK signaling pathways in NSCLC reveal a direct link between oncogenic drivers and PD-L1 expression.

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BackgroundStudies have suggested that chemotherapy after immune checkpoint inhibitors may confer an improved response for non–small cell lung cancer (NSCLC). However, potential selection bias in such studies has not been addressed. We therefore applied propensity score analysis to investigate the efficacy of chemotherapy after PD-1 inhibitor treatment (CAP) compared with chemotherapy alone.MethodsWe conducted a retrospective observational cohort study for patients treated at 47 institutions across Japan between April 1, 2014 and July 31, 2017. Eligible patients had advanced or recurrent NSCLC who have undergone chemotherapy. Patients subsequently treated with chemotherapy (docetaxel with or without ramucirumab, S-1 or pemetrexed) either after PD-1 inhibitor therapy (CAP cohort) or alone (control cohort) were included. The primary end point was objective response rate (ORR). Inverse probability weighting (IPW) was applied to adjust for potential confounding factors.ResultsA total of 1439 patients (243 and 1196 in the CAP and control cohorts, respectively) was available for unadjusted analysis. Several baseline characteristics—including age, histology,EGFRorALKgenetic alterations, and brain metastasis—differed significantly between the two cohorts. After adjustment for patient characteristics with the IPW method, ORR was 18.9% for the CAP cohort and 11.0% for the control cohort (ORR ratio 1.71; 95% CI 1.19 to 2.46; p=0.004). IPW-adjusted Kaplan-Meier curves showed that median progression-free survival (PFS) for the CAP and control cohorts was 2.8 and 2.7 months (IPW-adjusted HR 0.95; 95% CI 0.80 to 1.12; p=0.55), and median overall survival (OS) was 9.2 and 10.4 months (IPW-adjusted HR 1.05; 95% CI 0.86 to 1.28; p=0.63), respectively.ConclusionsAfter accounting for selection bias by propensity score analysis, CAP showed a significantly higher ORR compared with chemotherapy alone, with the primary end point of ORR being achieved. However, these results did not translate into a PFS or OS advantage, suggesting that prior administration of PD-1 inhibitors may result in a synergistic antitumor effect with subsequent chemotherapy, but that such an effect is transient. CAP therefore does not appear to achieve durable tumor control or confer a lasting survival benefit.

Background The aim of this study was to evaluate the potential of liquid biopsy for prediction of the efficacy of epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI) treatment and for assessment of the changes in genetic alterations during such treatment. Methods Plasma samples were prospectively collected from non–small cell lung cancer patients with EGFR‐activating mutations during EGFR‐TKI treatment until disease progression and were analyzed for such mutations with droplet digital polymerase chain reaction and for other somatic alterations with next‐generation sequencing. Results One hundred patients, including 87 who were EGFR‐TKI naïve, were enrolled. Median progression‐free survival was significantly shorter for EGFR‐TKI–naïve patients with EGFR‐activating mutations detected in plasma at baseline than for those without them (7.9 vs 19.0 months; P < .001), with the values being significantly longer for initially positive patients who became negative for these mutations at 12 or 24 weeks than for those who remained positive. An increase in the number of alleles positive for EGFR‐activating mutations in plasma during treatment was associated with disease progression, with a hazard ratio of 4.72 (95% CI, 2.07‐10.79; P < .001) for EGFR‐TKI–naïve patients showing an increase within 36 weeks. For 55 patients with available samples, the total number of somatic alterations (other than activating mutations or T790M of EGFR) in plasma was higher at disease progression than at baseline (33 vs 19; P = 0.04). Conclusion Liquid biopsy shows potential for prediction of EGFR‐TKI efficacy and elucidation of clonal tumor evolution during targeted therapy.