Background: The aim of this phase I study was to determine the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLTs) of an intermittent weekly capecitabine regimen in combination with oxaliplatin. Furthermore, we intended to explore its safety at the recommended dose, and to assess its principal antitumor activity in patients with advanced colorectal cancer.
Patients and methods: Thirty patients with measurable metastatic colorectal cancer who previously were unexposed to palliative chemotherapy were enrolled on to this disease-oriented phase I trial. They were treated with a fixed dose of oxaliplatin (85 mg/m(2) administered as a 2-h intravenous infusion on day 1) plus escalating doses of capecitabine (given at two divided daily doses from days 1 to 7), repeated every 2 weeks. The dose of oral fluoropyrimidine was escalated in consecutive cohorts of three to six patients from 2500 to 4000 mg/m(2)/day. After having defined the toxic dose, nine additional patients were entered at the MTD/recommended dose to confirm its safety profile, and assure suitability for future phase II/III studies.
Results: In the phase I part of the study, 21 patients were enrolled, and a total of 222 courses were administered through four dose levels of capecitabine combined with oxaliplatin 85 mg/m(2). Gastrointestinal toxicities, predominantly diarrhea, were the principal DLTs. Other severe adverse events included grade 3 asthenia, acute neurological symptoms and skin toxicity. The combination was not myelosuppressive, eliciting only sporadically grade 3/4 neutropenia and/or thrombocytopenia. There was no alopecia, and only a few patients experienced mild symptoms of hand-foot syndrome. Externally reviewed objective responses were noted in 15 of all 30 evaluable patients (overall response rate, 50%; 95% confidence interval 31% to 69%) including three complete remissions and median progression-free survival was 8.8 months (range 7-14+ months).
Conclusions: Overall results of this study indicate that the administration of clinically relevant single-agent doses of both capecitabine and oxaliplatin is feasible and seems to result in promising therapeutic activity in patients with advanced colorectal cancer. On the basis of the toxicological profile of the combination regimen shown in the present study, oxaliplatin 85 mg/m(2) as a 2-h intravenous infusion every 2 weeks administered in combination with capecitabine 3500 mg/m(2)/day x7 in two divided doses is recommended for further evaluations.