Concurrent modulation of 5-fluorouracil with methotrexate and L-leucovorin: an effective and moderately toxic regimen for the treatment of advanced colorectal carcinoma. A multicenter phase II study of the Southern Italy Cooperative Oncology Group.

AIMS AND BACKGROUND: Methotrexate (MTX) and leucovorin (LV) can enhance the cytotoxicity of 5-fluorouracil (5FU) by modifying its metabolic pathway inside target cells. Some preclinical studies and clinical trials have suggested that the concurrent or sequential double modulation of 5FU by means of MTX and LV may give a higher activity than single biochemical modulations. The purpose of our phase II study was to assess the activity and toxicity of a biweekly regimen including MTX, levo-LV and 5FU in colorectal cancer patients. METHODS: From July 1994 to May 1997, 100 consecutive patients affected by advanced or metastatic colorectal carcinoma were given MTX, 750 mg/m2 iv (2-h infusion) on day 1, and levo-LV, 250 mg/m2 iv (2-h infusion) followed by 5FU, 800 mg/m2 iv bolus on day 2, every two weeks. Patients were treated until complete response or progressive disease was documented, or for a maximum of 16 courses. RESULTS: Among 97 eligible patients, 5 complete and 25 partial responses were obtained, giving an overall response rate of 31% (95% exact confidence limits, 22-41%). Response rate was significantly higher in patients with a good (ECOG scale 0) than with a poor (ECOG scale 1 or 2) performance status (40% versus 17%, P <0.02). Median time to treatment failure was 27 weeks, median survival time was 63 (95% confidence limits, 54-71) weeks, and 2- and 3-year probability of survival were 34% and 12%, respectively. Performance status was the only pretreatment characteristic significantly affecting the outcome of patients. Indeed, median survival time was 94 weeks for patients with a performance status = 0 and 37 weeks for patients with a performance status > or = 1 (P<0.05). Toxicity of the treatment was low and manageable; grade 3 to 4 leukopenia affected 8% of patients, whereas grade 3 diarrhea and mucositis occurred in 5% and 4%, respectively. CONCLUSIONS: The double biochemical modulation of 5FU by MTX and levo-LV is at least as effective as, and probably more effective than, the single modulation by MTX or by LV. It may therefore represent a therapeutic option for the palliative treatment of patients with advanced colorectal carcinoma.