The Impact of PD-L1 and Correlated Markers on the Prognosis of Adenocarcinoma NSCLC Patients

Background: Programmed death ligand-1 (PD-L1) status in tumor pathology is a key factor that predicts the response to immune -checkpoint inhibitors (ICIs) in non-small cell lung cancer (NSCLC) patients. Given that not every patient has access to the PD-L1 level test, it is imperative to identify peripheral blood indicators that are correlated with PD-L1.Methods: The discovery cohort comprised 198 patients diagnosed with adenocarcinoma NSCLC. A retrospective analysis was conducted to investigate the value of systemic inflammation and tumor proliferation markers at baseline to reflect the level of PD-L1 expression, and the correlations between these baseline biomarkers and treatment outcomes were assessed.Results: PD-L1 >50% was significantly correlated with worse overall survival (OS) in advanced adenocarcinoma NSCLC pa-tients not receiving immunotherapy (p = 0.044). Nonetheless, PD-L1 was not a statistically significant prognostic indicator in patients treated with immunotherapy. C-reactive protein (CRP) levels were correlated with PD-L1 expression (r = 0.226, p = 0.001), while pretreatment CRP >5.78 mg/L emerged as an independent predictor of poor OS (HR = 1.65, 95% CI: 1.096-2.489, p = 0.017). Moreover, Ki-67 expression level was significantly correlated with PD-L1 level (r = 0.383, p < 0.0001), and Ki-67 >30% was validated as a predictor of an elevated progression risk (HR = 1.81, 95% CI: 1.200-2.720, p = 0.005). Interestingly, pretreatment CRP levels were also weakly correlated with Ki-67 expression level in the whole cohort (r = 0.174,p = 0.014). Conclusions: CRP and Ki-67 expression are strong indicators for PD-L1 expression and offer potential predictive value for the survival of adenocarcinoma NSCLC patients.