[Clinical study on regimen cyclophosphamide, Ara-C and topotecan (CAT) in treatment of patients with refractory or relapsed acute myelogenous leukemia].

Up to now, no consensus has been reached on the standard salvage regimen for patients with refractory or relapsed acute myeloid leukemia (AML). This study was purposed to evaluate the efficacy and safety of combination chemotherapy composing of cyclophosphamide (Cy), cytosine arabinoside (Ara-C) and topotecan (CAT regimen) for 37 refractory or relapsed AML patients. The dosing regimen was as follows: Cy 300 mg/m2 by intravenous infusion, every 12 hours on days 1-3, topotecan 1.25 mg/m2 by intravenous continuous infusion over 6 hours daily on days 2 to 6, Ara-C 500 mg/m2 by intravenous infusion over 2 hours daily for 5 days on days 2-6. The results showed that all patients completed one cycle of chemotherapy. 12 patients (32.4%) achieved complete remission (CR), 2 (5.4%) achieved partial remission (PR), and the 23 remaining patients achieved no remission (NR). The overall response rate (RR) was 37.8%. Among 18 relapsed cases, 6 cases had CR (33.3%), 2 cases achieved PR (11.1%), and 10 cases were with NR (55.6%). Among 19 refractory cases, 6 had CR (31.6%), and 13 (68.4%) were with NR. There was no statistically significant difference in RR between refractory and relapsed groups (31.6% and 44.4%, respectively) (p=0.42). Myelosuppression was universal. Mild non-hematologic toxicities were mainly gastrointestinal, as nausea, vomiting, diarrhea. The incidence of severe (grade III-IV) non-hematologic toxicity, such as oral mucositis and infection was 37.8% and 86.5% respectively. Only one patient died of severe infection during the observation (within 28 days from start of chemotherapy). The time of median follow-up was 4 (0-33) months, the median overall survival (OS) was 4 (1.8-6.2) months. The median OS for responders was longer than that for non-responders (9 vs 2 months respectively, p=0.00). In conclusion, the CAT regimen of lower dose is well tolerated and has certain anti-leukemia effect, and worthy to be further investigated.