TK-1, TP, Ang-2, and Tie-2 mRNA expression in plasma-derived microvesicles of chemo-refractory metastatic colorectal cancer patients

Background: Trifluridine/tipiracil and regorafenib are indicated for metastatic colorectal cancer (mCRC) patients' refractory to standard chemotherapy. No prognostic or predictive biomarkers are available for these agents. Methods: We assessed messenger ribonucleic acid (mRNA) expression of four biomarkers implicated in the mechanism of action of trifluridine/tipiracil (TK-1 and TP) and regorafenib (Ang-2 and Tie-2) in baseline plasma-derived microvesicles of chemo-refractory mCRC patients treated with these agents (trifluridine/tipiracil cohort and regorafenib cohort), to explore their prognostic and predictive role. Results: Baseline characteristics of the two cohorts were not different. Ang-2 mRNA was not detectable. Only TK-1 expression measured as a continuous variable was associated with progression-free survival (HR=1.09, 95%CI: 0.99-1.21; p=0.07) and overall survival (HR=1.11, 95%CI: 1.00-1.22; p=0.04), confirmed at multivariate analysis for progression-free survival (p=0.02) with a positive trend for overall survival (p=0.08). Baseline mRNA levels of TK-1, TP and Tie-2 were not predictive of trifluridine/tipiracil and regorafenib benefit. Conclusion: Baseline mRNA levels of TK-1, TP and Tie-2 on plasma-derived microvesicles were not predictive of trifluridine/tipiracil and regorafenib benefit. Future studies should analyze the early modulation of these biomarkers to assess their potential predictive role.