OUTLINE: The treatment plan consists of an IV infusion of trimetrexate, followed 24 hours later by IV infusions of leucovorin and fluorouracil. After another 24 hours oral leucovorin will be given every 6 hours for 7 doses. A treatment cycle consists of the regimen repeated weekly for 6 weeks followed by 2 weeks of rest. Treatment cycles will be repeated until disease progression or unacceptable toxicity.