Immune-related gene signature in predicting prognosis of early-stage colorectal cancer patients.

Abstract

3586 Background: Immune-related genes (IRGs) were found to be associated with the prognosis of colorectal cancer (CRC) patients. The aim of this study was to evaluate the impact of IRGs in predicting prognosis of early-stage CRC patients. Methods: According to the CIT microarray data set, 309 early-stage CRC patients were selected for generation of immune-related gene signature (IRGS). 5 independent data sets included 1587 CRC patients with complete prognostic information were divided into a training cohort (566 patients) and two validation cohorts (624 patients in validation-1 and 397 patients in meta-validation). Prognostic analysis were performed to test the predictive value of IRGS. Results: Of 309 early-stage CRC patients, a prognostic immune signature included 23 immune-related genes was constructed. In the training cohort, when considering patients with early tumor stage (I or II), IRGS significantly stratified patients into immune low- vs high-risk groups in terms of disease-free survival (HR = 5.03, 95%CI = 2.94-8.62, P < 0.001). Similarly, higher IRGS was correlated with significantly worse prognosis of early-stage CRC patients in validation-1 (HR = 2.71, 95%CI = 1.44-5.08, P = 0.001) and meta-validation cohort (HR = 3.10, 95%CI = 1.60-6.00, P < 0.001). When compared with Oncotype DX, we found IRGS achieved an improved survival correlation in the training cohort (mean C-index, 0.85 vs 0.65) and the validation-1 cohort (mean C-index, 0.72 vs 0.61). After integrated with clinical characteristics, IRGS remained as an independent prognostic factor after adjusting for T stage and TNM stage of tumor in multivariate analysis (HR = 2.02, 95%CI = 1.61-2.53, P < 0.001). Furthermore, IRGS stratified immune low-risk group patients with adjuvant chemotherapy showed even worse disease-free survival when compared with those without adjuvant chemotherapy (HR = 5.66, 95%CI = 3.153-10.16, P < 0.001 in the training cohort and HR = 3.21, 95%CI = 1.74-5.92, P < 0.001 in the validation-1 cohort). IRGS identified immune high-risk group obtained a significantly higher immune and stromal infiltration (P < 0.001). Particularly, the percentages of Macrophages M2 and CD8+ T cells infiltration were significantly different between these two groups. Conclusions: The proposed prognostic IRGS is a promising system for estimating DFS of colorectal cancer patients, especially those in early-stage. Further studies are needed to evaluate the clinical utility of this system in predicting prognosis of colorectal cancer patients.