A Phase I and Pharmacodynamic Study of Fludarabine, Carboplatin, and Topotecan in Patients With Relapsed, Refractory, or High-Risk Acute Leukemia

Abstract

Purpose: A novel regimen designed to maximize antileukemia activity of carboplatin through inhibiting repair of platinum-DNA adducts was conducted in poor prognosis, acute leukemia patients. Experimental Design: Patients received fludarabine (10 to 15 mg/m² × 5 days), carboplatin (area under the curve 10 to 12 by continuous infusion over 5 days), followed by escalated doses of topotecan infused over 72 hours (fludarabine, carboplatin, topotecan regimen). Twenty-eight patients had acute myelogenous leukemia (7 untreated secondary acute myelogenous leukemia, 11 in first relapse, and 10 in second relapse or refractory), 1 patient had refractory/relapsed acute lymphoblastic leukemia, and 2 patients had untreated chronic myelogenous leukemia blast crisis. Six patients had failed an autologous stem cell transplant. Patients ranged from 19 to 76 (median 54) years. Measurement of platinum-DNA adducts were done in serial bone marrow specimens. Results: Fifteen of 31 patients achieved bone marrow aplasia. Clinical responses included 2 complete response, 4 complete response with persistent thrombocytopenia, and 2 partial response. Prolonged myelosuppression was observed with median time to blood neutrophils ≥200/μl of 28 (0 to 43) days and time to platelets ≥20,000/μl (untransfused) of 40 (24 to 120) days. Grade 3 or greater infections occurred in all of the patients, and there were 2 infection-related deaths. The nonhematologic toxicity profile was acceptable. Five patients subsequently received allografts without early transplant-related mortality. Maximum tolerated dose of fludarabine, carboplatin, topotecan regimen was fludarabine 15 mg/m² × 5, carboplatin area under the curve 12, and topotecan 2.55 mg/m² over 72 hours. An increase in bone marrow, platinum-DNA adduct formation between the end of carboplatin infusion and 48 hours after the infusion correlated with bone marrow response. Conclusions: Fludarabine, carboplatin, topotecan regimen is a promising treatment based on potential pharmacodynamic interactions, which merits additional study in poor prognosis, acute leukemia patients.