Mitomycin C and High-Dose 5-Fluorouracil With Folinic Acid as a Therapeutic Option for Heavily Pretreated Patients With Metastatic Colorectal Cancer: Prospective Phase II Trial

Abstract

Standard treatment for patients with unresectable colorectal cancer metastases includes chemotherapy regimens based on irinotecan, oxaliplatin, fluoropyrimidines, anti-vascular endothelial growth factor therapy, and anti-EGFR. Additional therapeutic options are needed for patients with good performance status who have disease progression during or after standard therapies. A nonrandomized phase II study was modeled as a two-stage Chen design. Eligible patients had a diagnosis of metastatic colorectal cancer (mCRC) with progression after prior cytotoxic regimens based on oxaliplatin and irinotecan. Treatment consisted of mitomycin C in combination with high-dose 5-fluorouracil (5-FU) and folinic acid (the MLF regimen; mitomycin C as an intravenous bolus of 6 mg/m² i.v. on days 1 and 22 every 7 weeks; folinic acid at 250 mg/m² in combination with 5-FU at 2,600 mg/m² as a continuous intravenous infusion (24 hours) weekly for 6 of every 7 weeks. The median age of the 74 eligible patients was 62 years (range: 47-79 years). In these heavily pretreated patients with mCRC, the MLF regimen was the fourth or fifth line in more than 60% of the patients. Two patients (3.2%) achieved a partial response, and 33 (53.2%) achieved a best response of stable disease, defined as neither sufficient shrinkage to qualify for partial response nor sufficient increase to qualify for progressive disease. Median progression-free survival was 4.9 months. The median overall survival was 9.7 months. The most common nonhematologic side effects included mucositis (24.4% for all grades, and 9.5% with grade 3/4), diarrhea (15.0% for all grades, 13.6% with grade 3/4), fatigue (44.7% for all grades, 13.6% with grade 3/4), nausea (12.3% for all grades, 6.8% with grade 3/4), and peripheral neuropathy (17.6% for all grades, 2.7% with grade 3/4). Among the most frequent hematological toxicities were neutropenia (27.1% for all grades, 14.9% with grade 3/4), thrombocytopenia (18.9% for all grades, 8.1% with grade 3/4), and anemia (13.6% for all grades, 4.1% with grade 3/4). Dose reductions due to adverse events were necessary in 29 of 74 patients (37.6%), and discontinuation of therapy due to toxicity was necessary for 14 of 74 patients (18.2%). Our study shows the MLF regimen can be administered safely to patients with heavily pretreated mCRC. Median progression-free and overall survival compares favorably with other options used or approved in this setting. A randomized trial in this setting should be considered.