Soluble PD-L1 shows no association to relapse and overall survival in early stage non-small cell lung cancer (NSCLC).

BACKGROUND: Cancer immune evasion is critical in non-small cell lung cancer (NSCLC) and has been targeted by immunotherapy. High soluble (s)PD-L1 is associated with reduced survival and treatment failure in advanced stages. Here we evaluated the effects of sPD-L1 on T cells, relapse free survival, and overall survival in early stage NSCLC. METHODS: In vitro T cell stimulation was performed in the presence of sPD-L1 to evaluate its immunomodulatory activity. Data from The Cancer Genome Atlas (TCGA) were investigated for PD-L1 splice variants and enzymes involved in proteolytic cleavage (i.e. ADAM10). Plasma from 74 NSCLC (stage IA-IIIB), as well as an additional 73 (control cohort) patients was collected prior to curative surgery. Thereafter sPD-L1 levels from an immunosorbent assay were correlated with patient outcome. RESULTS: In vitro sPD-L1 inhibited IFN-γ production and proliferation of T cells and induced a terminal effector CD4 T cell subtype expressing CD27. Data from the TCGA demonstrated that elevated mRNA levels of ADAM10 is a negative predictor of outcome in NSCLC patients. To investigate the clinical relevance of these in vitro and TCGA findings, we quantified sPD-L1 in the plasma of early-stage NSCLC patients. In the first cohort we found significantly higher sPD-L1 levels in relapsing NSCLC patients, with a multivariate analysis revealing high sPD-L1 (>1000 pg/mL) as an independent predictor of survival. However, these findings could not be validated in two independent control cohorts. DISCUSSION: Although in vitro and TCGA data support the suppressive effect of sPD-L1 we were unable to translate this in our clinical setting. These results may be due to the small patient number and their heterogeneity as well as the lack of a standardized sPD-L1 ELISA. Our inconclusive results regarding the value of sPD-L1 in early stage NSCLC warrant assay validation and further investigation in larger (neo-)adjuvant trials.

Slug Is A Surrogate Marker of Epithelial to Mesenchymal Transition (EMT) in Head and Neck Cancer.

BACKGROUND: Epithelial to mesenchymal transition (EMT) promotes therapy resistance in head and neck cancer (HNC) cells. In this study, EMT was quantified in HNC tumor samples by the cellular co-localization of cytokeratin/vimentin, E­cadherin/ß­catenin and by Slug expression. METHODS: Tissue samples from HNC patients were stained with antibody pairs against cytokeratin/vimentin and E-cadherin/ß-catenin. Epithelial-mesenchymal co-localization was quantified using immunofluorescence multichannel image cytometry. Double positivity was confirmed using confocal microscopy. Slug was semi-quantified by 2 specialists and quantified by bright field image cytometry. RESULTS: Tumor samples of 102 patients were investigated. A loss of E-cadherin positive cells (56.9 ± 2.6% vs. 97.9 ± 1.0%; p < 0.0001) and E-cadherin/ß-catenin double positive cells (15.4 ± 5.7% vs. 85.4 ± 1.2%; p < 0.0001) was observed in tumor samples. The percentage of Slug positive cells was increased in tumor samples (12.1 ± 3.6% vs. 3.2 ± 2.6%; p = 0.001). Ordinal Slug scores judged by two specialists closely correlated with percentage of Slug-positive cells (Spearman's rho = 0.81; p < 0.001). Slug score correlated negatively with the percentage of E-cadherin positive cells (r = 0.4; p = 0.006), the percentage of E-cadherin/ß-catenin positive cells (r = 0.5; p = 0.001) and positively with cytokeratin/vimentin positive cells (r = 0.4, p = 0.003). CONCLUSION: EMT can be assessed in HNC tumor probes by cytokeratin/vimentin co-expression and loss of E-cadherin/ß-catenin co-expression. Slug score provides a convenient surrogate marker for EMT.