Phase II Open-Label Study of Oral Piritrexim in Patients with Advanced Carcinoma of the Urothelium Who Have Experienced Failure with Standard Chemotherapy

Abstract Background Piritrexim is reported to have a response rate of 38% in patients with chemotherapy-naive disease and 23% for second-line therapy after chemotherapy failure. We report the results of a multiinstitutional, open-label, 2-stage, phase II study that further evaluates oral piritrexim in patients with urothelial carcinoma and who proved nonresponsive to standard chemotherapy. Patients and Methods Eligible patients included those with bi-dimensionally measurable disease and an Eastern Cooperative Oncology Group performance status of 0-2, transitional cell carcinoma or adenocarcinoma of the urothelium, and nonresponse to ≤ 1 previous standard chemotherapy regimen. Patients received piritrexim orally at 25 mg 3 times daily (every 8 hours regularly) for 5 consecutive days each week for 3 weeks, followed by a 1-week rest period. Treatment was continued until disease progression, unacceptable toxicity, or patient refusal. Results Of the 23 patients enrolled, 19 patients and 22 patients were assessable for toxicity and response, respectively. Two patients required dose reduction because of toxicity, 2 patients discontinued study because of toxicity, and 6 patients had ≤ 1 serious adverse event. Except for grade 1/2 pain and fatigue, gastrointestinal toxicities were the most commonly reported events, followed by fever, delirium, and myelosuppression. No objective responses were observed, with 2 patients demonstrating stable disease after 2-4 cycles. By the statistical design of the trial, further enrollment was halted because of lack of activity. Conclusion Regardless of modest side effects, oral piritrexim in heavily pretreated patients is inactive at this dose and schedule, confirming the results of a recent cooperative group trial.