Second-line chemotherapy with a hybrid-alternating regimen of bolus 5FU modulated by methotrexate and infusional 5FU modulated by folinic acid in patients with metastatic colorectal cancer pretreated with 5FU. A phase 2 study.

Background And Aim: In vitro, methotrexate (MTX) is the best modulator for bolus 5-fluorouracil (5FU), whereas folinic acid (FA) is the best for continuous infusion. We evaluated the effect of 5FU modulated by both MTX (bolus administration) and FA (continuous infusion) as second-line treatment of patients with metastatic colorectal cancer.

Patients And Methods: Entry criteria were: at least one 5FU-based chemotherapy regimen as first-line treatment for metastatic disease, or progression within twelve months after 5FU-containing adjuvant therapy. Treatment schedule: MTX 200 mg/m2 i.v. days 1 and 15; 5FU 600 mg/m2 i.v. bolus, days 2 and 16; 5FU 200 mg/m2 i.v. continuous infusion for 21 days, starting on day 29; FA 20 mg/m2 i.v. bolus weekly during the three weeks of 5FU infusion. Cycles were repeated every 56 days. The primary end-point was tumour control rate, including partial responses and stabilizations.

Results: 34/35 patients enrolled were evaluable for response. Five (14.7%) had a partial response, 13 (38.2%) disease stabilization, and 16 (47.1%) progressed; tumour control rate was 52.9%. Median TTP was 5.8 months (95% CI 4.03-7.83); 29 patients had died. Median OAS was 15.9 months (95% CI 8.8-21.9). Toxicity was mild.

Conclusions: The regimen constituted by 5FU modulated by MTX (bolus administration) and FA (continuous infusion) is active as second-line treatment of metastatic colorectal cancer.