Increased tolerability of bimonthly 12-hour timed flat infusion 5-fluorouracil/irinotecan regimen in advanced colorectal cancer: A dose-finding study

A dose-finding study was designed to determine the maximum tolerated dose (MTD) of a bimonthly 12-h (10:00 p.m to 10:00 a.m), timed flat infusion (TFI) of 5-fluorouracil (5-FU) plus irinotecan (CPT-11), without leucovorin (LV), for metastatic colorectal carcinoma (CRC). A total of 33 patients were treated. Seven dose levels included a fixed CPT-11 dose of 180 mg/m2 on days 1 and 15 (d1,15) and escalating doses of 5-FU 600-1200 mg/m2 on days 1-4 and 15-18 (d1-4,15-18). Dose-limiting toxicities (DLTs) were: grade 3-4 non-hematologic, grade 4 hematologic and any toxicity causing a more than a 2-week delay in treatment. The MTD was reached at the seventh dose level. DLTs were observed in 5/8 patients (63%): G3 diarrhea, 2 patients, associated with G3 mucositis in one instance; G4 neutropenia, 2 patients, associated with severe asthenia in 1 patient; G3 hand-foot syndrome, 1 patient. The recommended doses (RDs) were established at the sixth dose level: 5-FU, 1100 mg/m2/d1-4,15-18; CPT-11 180 mg/m2/d1,15 [5-FU and CPT-11 dose intensity (DI), 2200 and 90 mg/m2 per week (w), respectively]. At the recommended dose, the DLTs in 38 cycles were: mucositis, 2 cycles (5%); afebrile G4 neutropenia and hand-foot syndrome, 1 cycle (3%). In 24 assessable patients, the overall response rate was 37.5%. The present CPT-11/5-FU schedule is highly tolerable in an outpatient setting using the highest recommended 5-FU dose effective in advanced CRC.