Soluble PD-L1 and Serum Vascular Endothelial Growth Factor-B May Independently Predict Prognosis in Patients with Advanced Non-Small Cell Lung Cancer Treated with Pembrolizumab

<b>Background:</b> Previous preclinical data have shown that the dynamic cross-talk between abnormal tumor vasculature and immune cell factors in the tumor microenvironment may exert a critical role in the progression and treatment resistance of non-small cell lung cancer (NSCLC). In the clinical setting, a variety of blood-based angiogenesis- and immune-related factors are being increasingly investigated as potential biomarkers of prognosis or treatment response in immunotherapy-treated NSCLC. We herein aimed to evaluate the clinical relevance of the peripheral blood levels of vascular endothelial growth factor-A and -B (VEGF-A and VEGF-B, respectively), soluble programmed cell death-1 (sPD-1), and programmed cell death-ligand 1 (sPD-L1) in patients with advanced NSCLC treated with immune checkpoint inhibitors (ICIs). <b>Methods:</b> Consecutive patients with advanced-stage, non-oncogene-addicted NSCLC, eligible to receive ICIs at the Oncology Unit of Sotiria Athens General Hospital, were prospectively recruited. A group of sex- and age-matched healthy controls was also enrolled for the evaluation of the potential diagnostic significance of the examined biomarkers. Serum levels of all biomarkers were measured using ELISA, both before and after treatment, and were correlated with standard clinicopathological features of patients, treatment response, progression-free survival (PFS), and overall survival (OS). <b>Results:</b> A total of 55 patients and 16 healthy controls were included in the final analysis. The mean age of patients and controls was 66.5 years (SD = 8.0 years) and 65.4 years (SD = 9.1 years), respectively. The majority of patients (65.5%) received pembrolizumab in combination with chemotherapy, while the remaining patients received pembrolizumab monotherapy. ROC curve analysis showed that VEGFB and sPD-1 were the only markers with a significant diagnostic value. Higher pre-treatment values of sPD-L1 (HR = 1.68; <i>p</i> = 0.040) and sPD-1 (HR = 10.96; <i>p</i> = 0.037) as well as higher post-treatment values of VEGF-B (HR = 2.99; <i>p</i> = 0.049) were all significantly associated with a reduced OS in univariate Cox regression analysis. The adverse prognostic significance of higher pre-treatment values of sPD-L1 (HR = 2.10; <i>p</i> = 0.014) and higher post-treatment values of VEGFB (HR = 3.37; <i>p</i> = 0.032) was further confirmed in multivariate analysis. <b>Conclusions:</b> Our study results suggest that serum levels of sPD-L1 and VEGF-B may independently predict prognosis in ICI-treated advanced-stage NSCLC.