Phase I and pharmacological study of two schedules of the antifolate edatrexate in combination with cisplatin.

ABSTRACT

The antifolate edatrexate has shown moderate activity against cancers of the head and neck and non-small cell lung cancer, as has cisplatin. Edatrexate demonstrates synergy with cisplatin in transplanted tumor models. This Phase I study was designed to evaluate two schedules of administration of cisplatin in combination with escalating doses of edatrexate, in a population consisting mainly of patients with these two cancers. The starting dose of edatrexate was 40 mg/m2. Dose escalation was to occur in 10-mg/m2 increments; the planned maximum dose level for study was 80 mg/m2. A total of 39 patients were registered. Eleven were treated on schedule A cisplatin 120 mg/m2 every 4 weeks, and edatrexate weekly. Twenty-eight patients were assigned to schedule B cisplatin 60 mg/m2 and edatrexate, both given every 2 weeks. On schedule A, the maximum tolerated dose of weekly edatrexate was 40 mg/m2, with dose-limiting toxicities of leukopenia, mucositis, and renal insufficiency. On schedule B, the maximum tolerated dose of biweekly edatrexate was 80 mg/m2, with leukopenia and mucositis as dose limiting. For schedule A, pharmacokinetic studies suggested a possible effect of cisplatin on the day 8 clearance of edatrexate. Studies on patients on schedule B did not show a clear effect of cisplatin on the day 15 edatrexate clearance. On schedule A, 5 of 9 evaluable patients had major responses (1 complete); whereas on schedule B, 8 of 25 patients had major responses (1 complete). Responses were seen in both head and neck and non-small cell lung cancer patients. For Phase II studies, use of cisplatin 60 mg/m2 and edatrexate 80 mg/m2, both given biweekly, is recommended.