Raltitrexed/5-fluorouracil-based combination chemotherapy regimens in anticancer therapy.

Preclinical evidence of a schedule-dependent synergism between raltitrexed and 5-fluorouracil (5-FU) has prompted clinical studies of this combination. We review the main preclinical and clinical results of raltitrexed/5-FU-based combination chemotherapy regimens in anticancer therapy. Promising results include: response rates of 25 and 23% with combinations of raltitrexed/5-FU/levofolinic acid (LFA) as first-line treatment and oxaliplatin/raltitrexed/5-FU/LFA as second-line treatment of metastatic colorectal cancer, respectively; and a 67% response rate in a phase I study of cisplatin/raltitrexed/5-FU/LFA as first-line treatment of advanced head and neck cancer, including a 100% response rate at the recommended dose. These combinations were well tolerated, with neutropenia as the main dose-limiting toxicity, allowing the drugs to be combined at the doses used in monotherapy. These results suggest a role for raltitrexed within combination regimens in colorectal cancer therapy, as well as other tumors such as head and neck cancer. A further potential application of raltitrexed in combination therapies is within multidisciplinary chemo-radiotherapy strategies, mainly in rectal cancer. Phase II studies are planned/ongoing to investigate these interesting possibilities.