A phase I study to determine the maximum tolerated dose of trifluridine/tipiracil and oxaliplatin in patients with refractory metastatic colorectal cancer: LUPIN study

Background The effectiveness of reintroducing oxaliplatin for metastatic colorectal cancer (mCRC) refractory to both oxaliplatin and irinotecan was previously reported in a phase II study (RE-OPEN). We conducted a phase I study to determine the maximum tolerated dose of oxaliplatin plus trifluridine/tipiracil (FTD/TPI) in patients with refractory mCRC. Patients and Methods Three dosages of intravenous oxaliplatin (50, 65 and 85 mg/m²) on days 1 and 15 and a fixed dose of FTD/TPI 35 mg/m² twice daily (bid) on days 1–5 and 15–19 every 4 weeks were investigated in patients with refractory mCRC using a 3 + 3 design. Eligible patients had received prior oxaliplatin-based treatment that achieved a response or stable disease followed by confirmed disease progression at least 6 months before entering the study. Results Twelve patients were enrolled in the study. Three of six patients in the oxaliplatin 85 mg/m² cohort had dose-limiting toxicities (DLTs) with treatment delays during the second cycle at ≥8 days due to grade ≥ 2 neutropenia or grade 2 AST/ALT increased. No DLTs were observed in the other cohorts. Grade ≥ 3 AEs were neutropenia (n = 3), thrombocytopenia (n = 1), anorexia (n = 1), and nausea (n = 1). There was no evidence of allergic reaction to oxaliplatin or severe peripheral sensory neuropathy. Conclusions A combination of FTD/TPI 35 mg/m² bid on days 1–5 and 15–19 and oxaliplatin 85 mg/m² on days 1 and 15 every 4 weeks could be a suitable regimen for the recommended dose of FTD/TPI plus oxaliplatin in patients with refractory mCRC.