Kinetics of Plasma cfDNA Predicts Clinical Response in Non-Small Cell Lung Cancer Patients

Background: Tyrosine Kinases Inhibitors (TKIs), VEGF/VEGF receptor inhibitors (VEGFIs, bevacizumab) and immune checkpoint inhibitors (ICIs) have revolutionized the treatment of advanced cancer including non-small-cell lung cancer (NSCLC). Cell-free DNA (cfDNA) has been adapted as a convenient liquid biopsy that reflects characteristics of the status of both the primary and metastatic tumors, assisting in personalized medicine. This study aims to evaluate the utility of cfDNA as a prognostic biomarker and efficacy predictor of chemotherapy with or without these precision therapies in NSCLC patients. Methods: Peripheral cfDNA levels were quantified in 154 patients with NSCLC before (baseline) and after (post-chemotherapy) the first target cycle of chemotherapy. These patients were divided into four subgroups receiving chemotherapy only, chemotherapy plus TKIs, chemotherapy plus VEGFIs, and chemotherapy plus immune checkpoint inhibitors (ICIs), respectively. The correlations of cfDNA with tumor burden, clinical characteristics, progression-free survival (PFS), objective response ratio (ORR), and therapy regimens were analyzed. Results: Baseline cfDNA, but not post-chemotherapy, positively correlates with tumor burden. cfDNA Ratio (post-chemotherapy/baseline) well distinguished responsive individuals (CR/PR) from non-responsive patients (PD/SD). Additionally, cfDNA Ratio was found to be negatively correlated with PFS in lung adenocarcinoma (LUAD), but not in lung squamous-cell carcinoma (LUSC). LUAD patients with low cfDNA Ratio benefit significantly including prolonged PFS and improved ORR, compared with those with high cfDNA Ratio. When stratified by therapy regimen, the predictive value of cfDNA Ratio is significant in patients with chemotherapy plus VEGFIs. Conclusion: The kinetics of plasma cfDNA during the chemotherapy may function as a prognostic biomarker and efficacy predictor for NSCLC patients.