Phase I–II trial of 14 day infusional 6-Mercaptopurine in advanced colorectal cancer

Abstract 6-Mercaptopurine (6-MP) is a cycle specific antineoplastic agent with a short serum half-life following bolus administration, providing a rationale for continuous infusional administration of the parenteral formulation. 22 patients received 38 courses of 14 day 6-MP infusion. The maximum tolerated dose (MTD) was 35 mg/m 2 /day (total dose per 14 day cycle 490 mg/m 2 ) with cycles repeated at 28 days. Toxicities included transient hyperbilirubinaemia, leucopenia and thrombocytopenia. 13 evaluable patients with advanced colon cancer resistant to 5-fluorouracil with or without leucovorin received infusional 6-MP at the MTD as part of the phase II study analysis, but no objective responses were observed. Phase II studies in previously untreated patients and longer infusion durations are being evaluated.