Successful Salvage Treatment With Clofarabine and Cytarabine In Relapsed/Refractory Acute Myeloid Leukemia

Abstract

ObjectivesRelapsed/refractory AML patients have a poor prognosis; allogeneic hematopoietic stem cell transplantation (HSCT) is the only chance in this setting to achieve long-term disease-free survival (1). It was previously established the activity of clofarabine plus cytarabine in AML relapse (clofarabine dosed once daily for 5 days with 40 mg/m2 followed 4 hours later by ara-C at 1 g/m2 per day)(2).However, modifications of this combination in AML therapy of relapsed/refractory patients warrant further evaluation. Therefore, our goal was to determine the efficacy and safety of clofarabine at lower dosage followed by cytarabine (Ara-C) in adult patients with relapsed or refractory acute myeloid leukemia (AML) and to evaluate the capacity of this regimen as a bridge for HSCT. MethodsPatients aged 18-65 years with refractory/relapsed AML were treated at the dose of clofarabine 30 mg/mq on days 1-5 and cytarabine 1000 mg/mq gg on days 1-5. We evaluated the complete remission rate (CRR), duration of remission (DOR) and overall survival (OS). Minimal residual disease (MRD) by molecular targeting was considered in all patients. ResultsTwenty-five (25) patients aged 29-64 years (median 47), who were fit for allogenetic HCT, received one cycle of 30 minutes infusion of clofarabine 30 mg/mq, followed 4 hours later by 3 hours infusion of intermediate dose cytarabine 1000 mg/mq days 1-5. Only in the first three patients this schedule was followed by gentuzumab. Nine (36%) patients had refractory disease (seven after one induction regimen, one after two previous regimes, one after a prior hematopoietic stem cell transplant (HSCT); 16 (64%) patients were in their first (12 patients) or second relapse (4 patients); among the 12 patients in first relapse, 5 were from an allogeneic stem cell transplant. Fourteen patients (56%) achieved a complete remission (CR), seven (28%) was refractory and 4 (16%) died of treatment related mortality. Eleven (44%) patients underwent (9 in CR) to allogeneic transplants or DLI infusion (3 patients refractory, and 8 patients relapsed), only one patient underwent to autologous transplant. One patient, who was relapsed after prior HSCT, obtained a CR but he developed acute graft vs host disease after therapy and died in molecular CR*. Among all patients underwent HSCT after Clofa/Ara-c salvage, six patients (50%) are still alive and in complete remission, six patients (50%) died because of HSCT complications or AML relapse. The complete remission rate (CRR) was (56,00 %), the median Overall Survival was 5 months for all patients (range 1-38 M), 11 Months for those underwent to tranplantation and 1,5 Months for non transplanted group. Treatment was complicated by neutropenic fever (n=17), grade III-IV mucositis (n=2) , skin rush (n=4) grade II- III, hepatic transaminase elevations (n=2). Two (n=5) patient died before their disease status could be evaluated. ConclusionsThese preliminary results suggest that combination treatment with clofarabine 30 mg/mq and ARA-C 1000 mg/mq is effective in this particularly poor prognosis category of patients, resulting in an ORR very favorably, representing a potential “bridge” toward bone marrow transplant procedures (among the 14 patients who achieved a CR, twelve (85%) proceeded to HSCT, and six are still alive). The safety profile is acceptable in this relapsed/refractory population, and our results are very similar to previous regimes using higher clofarabine dosages. More studies with this combination in adults are warranted. References1 Estey E. Treatment of relapsed and refractory acute myeloid leukemia. Leukemia. 2000;14:476-479. 2. Faderl S et al, “Results of a pase 1-2 study of clofarabine in combination with cytarabine (ara-C)”Blood 2005 [Display omitted] [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.