Immune-related Genes to Dominate Neutrophil-lymphocyte Ratio (NLR) Associated With Survival of Cetuximab Treatment in Metastatic Colorectal Cancer

Our study, using data of prospective trials, demonstrated that the neutrophil-lymphocyte ratio (NLR) was associated with survival time in patients with KRAS wild-type metastatic colorectal cancer treated with first line chemotherapy with cetuximab. The expression levels of the LYZ, TYMP, and CD68 genes differed significantly between the NLR-low and NLR-high groups. Genes encoding for activities on macrophages may affect the NLR. Background: Few clinical studies have investigated the association between neutrophil-lymphocyte ratio (NLR) and treatment with cetuximab-based chemotherapy in metastatic colorectal cancer (mCRC). The NLR may reflect immune cells modulating specific cytokine signals in the tumor microenvironment; however, which immune-related genes affect the NLR remain unclear. Patients and Methods: In 77 patients with KRAS exon2 wild-type mCRC from prospective trials of first-line chemotherapy with cetuximab, expression levels of 354 immune-related genes were measured in tissue samples obtained from all patients by the HTG EdgeSeq Oncology Biomarker Panel. The association between the NLR and clinical outcomes was evaluated using the Spearman rank correlation coefficient. In addition, 2-sample t tests were performed to investigate which genes among the top 100 genes associated with survival had significantly different expression levels between the NLR-low and NLR-high groups among all measured genes. Results: NLR data were available for 71 patients. The NLR was associated with progression-free survival and overall survival (r = - 0.24; P = .040 and r = - 0.29; P = .010, respectively). When stratified by the median value of the NLR, the Kaplan-Meier curve of NLR-low versus NLR-high differed significantly for both progression-free survival (median, 11.8 vs. 9.1 months; P = .036) and overall survival (median, 42.8 vs. 26.7 months; P = .029). The 2-sample t test revealed that the expression levels of the LYZ, TYMP, and CD68 genes differed significantly between the NLR-low and NLR-high groups (t test P-value < .005; false discovery rate P-value < .15). Conclusion: NLR is significantly associated with survival in patients with mCRC treated with first-line chemotherapy with cetuximab. Genes encoding for activities on macrophages may affect the NLR. (C) 2018 Elsevier Inc. All rights reserved.