Tumor Response to Irinotecan is Associated with IL-10 Expression Level in Metastatic Colorectal Cancer-Results from mCRC Biomarker Study.

Purpose: Metastatic colorectal cancer (mCRC) is a leading cause of cancer-related death. Resistance to chemotherapy is the main reason for the failure of the treatment of mCRC. IL-10 has been reported to decrease after surgery and increase after mCRC reoccurrence. The role of IL-10 in chemotherapy drug resistance of mCRC is not well elucidated.

Patients And Methods: The retrospective study recruited 264 mCRC patients between January 2012 and December 2016 (NCT03532711). All the enrolled patients received an oxaliplatin-containing or irinotecan-containing regimen. The expression level of IL-10 in 232 patients' plasma and 68 patients' tumor tissue was examined. The relationships between IL-10 and clinicopathological characteristics were analyzed. Kaplan-Meier method and Cox regression were used to evaluate the prognostic impact of IL-10.

Results: The median concentration of IL-10 was 7.60 pg/mL before treatment and 11.08 pg/mL after treatment, which suggested that IL-10 level was significantly increased by treatment with a chemotherapeutic regimen (p = 0.000). By utilizing univariate and multivariate Cox proportional hazard analyses, we found that low IL-10 level in plasma was significantly associated with improved overall survival (OS) of mCRC patients treated with irinotecan-containing regimen-with optimal cutoff value of 5.525pg/mL, respectively (p =0.002). In addition, the low IL-10 expression level in tumor tissue was significantly associated with the improved OS for the irinotecan-containing regimen (p = 0.023).

Conclusion: Our study demonstrated that IL-10 could act as a prognostic biomarker for mCRC patients undergoing irinotecan-containing chemotherapy.