Modified Topotecan Combination with Cyclophosphamide and Ara-C (CAT) for Patients with Refractory/Relapsed Leukemia.

The prognosis of patients with leukemia has improved significantly. With combination chemotherapy, 60%–80% of adult patients with acute myeloid leukemia (AML) and acute lymphoblastic leukemia(ALL) achieve complete remission(CR). But most patients eventually relapse and do not response to current induction regimens based on cytarabine and anthracyclines any more. This emphasize the need to discover new agents for the treatment of leukemia to improve long-term prognosis. Topotecan is a semisynthetic analogue of the alkaloid camptothecin which acts as a specific inhibitor of topoisomerase I,by stabilization of the topoisomerase I DNA complex which leads to cell death.It also appears to be active against leukemias which have acquired the multi-drug resistant phenotype.[ Ulukan et al. Drug, 2000; Weihrauch et al. Leuk Lymphoma, 2004].It also could go through blood brain barrier[Kollmannsberger et al. Oncology, 1999].Here we observe the effect and side-effects of cyclophosphamide, cytanthetic analogue of rabine and topotecan (Modified CAT) combination regimen for treatment of refractory or relapsed leukemia. The study population comprise 26 patients with relapsed/refractory leukemia,including 12 with AML, 9 with ALL, 2 with myeloid blast phase of CML, 3 with lymphoma. Median age was 35 years.Patients received cyclophosphamide 300mg/m² every 12 hours for 6 doses on day1 to 3.On day 2, topotecan was given at a dose of 1.5mg/m²/day for 5 days on days 2 to 6, and cytarabine 1.0 g/m² /day for 5 days on days 2 to 6.The regimen (cytarabine reduced to 0.5g/m² /day) could be repeated one or two cycles after remission. The total response rate of one course was 57%, eleven patients (42%) achived complete remission(CR). Responses occurred in 7of 12 AML (57%), including 5 CR(41%); in 6 of 9 patients with ALL (67%), including 5 CR(56%); and in 1 of 2 myeloid blast phase of CML(CR 50%). The median overall survival time after treatment was 2+ months, and the median overall survival time after CR was 4+ months. Severe myelosuppression was universal (100% Grade 4 neutropenia and thrombocytopenia), the median time to recovery of neutrophils to ≥0.5×10⁹/L was 18 days,and the median time to platelet recovery to ≥ 20×10⁹/L was 26 days.Infection developed in 96% cases, the most frequent events were oral mucositis(77%, 20/26), sepedogenesis(46%, 12/26),anusitis(38%,10/26),pneumonia(31%, 8/26), two patients died of infection complications(8%). Non-hematologic toxicity was seen frequently in gastrointestinal but it was mild. Nausea and/or vomiting occurred in 13 patients(50%)with gradeI-II in all of them.Two patients(8%) had diarrhea and grade 1–2 in them. In summary, Modified CAT regimen is well tolerated and has significant anti-leukemia activity as salvage therapy for relapsed/refractory leukemia.