Human Leukocyte Antigen-DR Expression on Monocytes Is a Useful Predictor in a Systemic Inflammation Response-Based Prognostic Model in Advanced Non-Small Cell Lung Cancer

Inflammation and immune evasion promote tumorigenesis and progression. Elevated systemic inflammation response index (SIRI) is associated with poor progression-free survival (PFS) and overall survival (OS) in non-small cell lung cancer (NSCLC) patients. Low Human Leukocyte Antigen-DR (HLA-DR) expression on monocytes is also associated with poor prognosis in NSCLC. We aimed to investigate the relationship between these two indicators and develop a predictive model based on them. SIRI was calculated and monocyte HLA-DR expression was measured by flow cytometry in 58 advanced (stage IIIB-IV) NSCLC patients. The log-rank test and multivariate Cox proportional hazard regression model were used for analysis. We confirmed that both high SIRI and low monocyte HLA-DR expression were associated with poor PFS and OS, respectively. We found a significant inverse correlation between SIRI and monocyte HLA-DR expression. In the multivariable Cox regression model, both SIRI and monocyte HLA-DR expression were identified as independent prognostic markers for PFS and OS. We also developed a nomogram for predicting PFS and OS. In conclusion, we demonstrated that the systemic inflammation response of advanced NSCLC patients, estimated by SIRI, was associated with reduced HLA-DR expression on circulating monocytes, which may influence their antigen-presenting function. Consequently, the integration of these two biomarkers into one prognostic model improves short term survival prediction in advanced NSCLC. To our knowledge, this is the first integration of SIRI and HLA-DR into a combined prognostic nomogram.