- Faderl, Stefan;
- Balakrishnan, Kumudha;
- Thomas, Deborah A;
- Ravandi, Farhad;
- Borthakur, Gautam;
- Burger, Jan;
- Ferrajoli, Alessandra;
- Cortes, Jorge;
- O'Brien, Susan;
- Kadia, Tapan;
- Feliu, Jennie;
- Plunkett, William;
- Gandhi, Varsha;
- Kantarjian, Hagop M
Background
Clofarabine is a nucleoside analogue with activity in children with acute lymphoblastic leukemia (ALL). Based on the hypothesis that clofarabine inhibits DNA repair after exposure to DNA-damaging agents, we designed a phase I and extension study to evaluate the combination of clofarabine and cyclophosphamide in adult patients with relapsed/refractory ALL.Methods
The continual reassessment method (CRM) was used to define the maximum tolerated dose (MTD).Results
Fifty patients with a median age of 30 years (range, 21-72 years) were enrolled, 30 of whom were part of the phase I group. Clofarabine 40 mg/m(2) intravenously daily × 3 days and cyclophosphamide 200 mg/m(2) intravenously every 12 hours × 3 days were established as the MTDs. Dose limiting toxicity (DLT) included diarrhea, transaminase elevations, and skin rashes. The response rate of the whole study group was 14%, including 10% of patients who achieved complete remission (CR) or CR without platelet recovery (CRp). Three responses occurred in patients with primary refractory disease. Early mortality (< 30 days) was 6%. The median duration of response was 69 days (range, 5-315 days). Median overall survival was about 3 months. Compared with day 1 (cyclophosphamide alone), H2AX phosphorylation was increased on day 2 when clofarabine and cyclophosphamide were administered as a couplet (n = 8).Conclusion
The combination of clofarabine plus cyclophosphamide at the doses used in this study in a group of heavily pretreated patients with ALL is only moderately effective. Other doses, alternative schedules, or a more favorable patient population may achieve better results.