A Phase I dose-escalation study of third-line regorafenib with trifluridine/tipiracil in metastatic colorectal cancer.

ABSTRACT

Aim: To determine a recommended Phase II dose of the oral fluoropyrimidine trifluridine/tipiracil (FTD/TPI) combined with the multi-kinase inhibitor regorafenib (REG) in refractory metastatic colorectal cancer patients. Materials & methods: A conventional 3 + 3 dose finding design was used. FTD/TPI was administered on days 1-5 and 8-12 of a 28-day cycle, REG on days 2-22. Two dose levels were used FTD/TPI 25 mg/m2 b.i.d. + REG 120 mg/d, then escalated to FTD/TPI 35 mg/m2 b.i.d. + REG 120 mg/d. Results: In total, 12 patients were treated at two dose levels. Three dose-limiting toxicities were observed; all were grade 3 hypertension causally attributed to REG. Recommended Phase II dose is FTD/TPI 25 mg/m2 b.i.d. + REG 120 mg/d. Median progression-free survival was 3.81 months (95% CI 1.51-5.29), median OS 11.1 months (95% CI 2.3-18.2). Conclusion: The combination of REG and FTD/TPI is feasible and safe. Efficacy signals exceed that of the single agents at acceptable toxicity levels and are clinically meaningful.

Lay abstract Many patients with metastatic colorectal cancer need a sequence of different treatments over time. Regorafenib and trifluridine/tipiracil (also called TAS-102) are two drugs which are both used late in this sequence of treatments, but there is no rule as to which should be used first. Both drugs have very different mechanisms of action, and it might be beneficial to patients to administer them both at the same time as a combination treatment, instead of sequential treatment. We therefore conducted a Phase Ib study with a small number of patients to investigate whether this combined treatment would be feasible and safe. The study was designed to test the drug combination at different doses, and we found that treatment with trifluridine/tipiracil at 25 mg/m2 twice daily combined with regorafenib at 120 mg daily had acceptable side effects and is likely to be safe for use in future clinical trials. Efficacy results suggest that combined treatment with both drugs may extend patient's life span. However, these observations are preliminary and need testing in further clinical trials. Clinical trial registration EudraCT 2016-001968-11; NCT03305913 (ClinicalTrials.gov).