Toxicity study of cytosine arabinoside and methotrexate in the maintenance therapy of childhood leukemia. A Southwest Oncology Group study.

In a toxicity study to determine the feasibility of treating patients with acute lymphocytic leukemia (ALL) using an intravenous combination of cytosine arabinoside (Ara-C) and methotrexate (MTX), the drugs were given either simultaneously or sequentially every two weeks. Twenty-nine patients were studied, 17 treated simultaneously, 12 treated sequentially. The tolerated doses of Ara-C and MTX were 60 mg/m2 and 90 mg/m2, respectively, for the simultaneous treatment schedule and 90 mg/m2 and 150 mg/m2, respectively, for the sequential treatment schedule. The dose-limiting factor of the drug combination was gastrointestinal toxicity. The observed recurrent vomiting on both schedules rendered the treatment unsuitable for maintenance therapy.