Final results of a phase 2 trial of clofarabine and low-dose cytarabine alternating with decitabine in older patients with newly diagnosed acute myeloid leukemia.

BACKGROUND: The treatment of older adults with acute myeloid leukemia (AML) using standard intensive chemotherapy has been associated with poor outcomes. Effective, less toxic therapies are needed to achieve and maintain durable remissions. METHODS: One hundred eighteen patients with newly diagnosed AML (median age, 68 years; range, 60-81 years) were treated with a regimen of clofarabine and low-dose cytarabine (LDAC) alternating with decitabine (DAC). The induction consisted of intravenous clofarabine at 20 mg/m(2) on days 1 to 5 combined with subcutaneous LDAC at 20 mg twice daily on days 1 to 10. Responding patients were then treated with a prolonged consolidation/maintenance regimen consisting of cycles of clofarabine plus LDAC alternating with cycles of DAC. RESULTS: The overall response rate was 68%. The complete remission (CR) rate was 60% overall, 71% for patients with a diploid karyotype, and 50% for patients with an adverse karyotype. The median overall survival (OS) was 11.1 months for all patients and 18.5 months for those achieving a CR/complete remission with incomplete platelet recovery (CRp). The median relapse-free survival for patients achieving a CR/CRp was 14.1 months. According to a multivariate analysis, only adverse cytogenetics and a white blood cell count ≥ 10 × 10(9)/L predicted worse OS. The regimen was well tolerated with 4- and 8-week mortality rates of 3% and 7%, respectively. The most common nonhematologic adverse events were nausea, elevated liver enzymes, and rash. CONCLUSIONS: The lower intensity, prolonged-therapy program of clofarabine and LDAC alternating with DAC is well tolerated and highly effective in older patients with AML.

Phase I/II study of the hypoxia-activated prodrug PR104 in refractory/relapsed acute myeloid leukemia and acute lymphoblastic leukemia.

We previously demonstrated vast expansion of hypoxic areas in the leukemic microenvironment and provided a rationale for using hypoxia-activated prodrugs. PR104 is a phosphate ester that is rapidly hydrolyzed in vivo to the corresponding alcohol PR-104A and further reduced to the amine and hydroxyl-amine nitrogen mustards that induce DNA cross-linking in hypoxic cells under low oxygen concentrations. In this phase I/II study, patients with relapsed/refractory acute myeloid leukemia (n=40) after 1 or 2 prior treatments or acute lymphoblastic leukemia (n=10) after any number of prior treatments received PR104; dose ranged from 1.1 to 4 g/m(2). The most common treatment-related grade 3/4 adverse events were myelosuppression (anemia 62%, neutropenia 50%, thrombocytopenia 46%), febrile neutropenia (40%), infection (24%), and enterocolitis (14%). Ten of 31 patients with acute myeloid leukemia (32%) and 2 of 10 patients with acute lymphoblastic leukemia (20%) who received 3 g/m(2) or 4 g/m(2) had a response (complete response, n=1; complete response without platelet recovery, n=5; morphological leukemia-free state, n=6). The extent of hypoxia was evaluated by the hypoxia tracer pimonidazole administered prior to a bone marrow biopsy and by immunohistochemical assessments of hypoxia-inducible factor alpha and carbonic anhydrase IX. A high fraction of leukemic cells expressed these markers, and PR104 administration resulted in measurable decrease of the proportions of hypoxic cells. These findings indicate that hypoxia is a prevalent feature of the leukemic microenvironment and that targeting hypoxia with hypoxia-activated prodrugs warrants further evaluation in acute leukemia. The trial is registered at clinicaltrials.gov identifier: 01037556.

Clofarabine plus low-dose cytarabine followed by clofarabine plus low-dose cytarabine alternating with decitabine in acute myeloid leukemia frontline therapy for older patients.

BACKGROUND: Standard therapy for older patients with acute myeloid leukemia (AML) has a poor outcome. The authors have designed a combination of clofarabine plus low-dose cytarabine followed by a prolonged consolidation alternating with decitabine. METHODS: Sixty patients with a median age of 70 years (range, 60-81 years) with newly diagnosed AML were included. They received clofarabine 20 mg/m(2) intravenously daily for 5 days plus cytarabine 20 mg subcutaneously twice daily for 10 days. Responding patients continued for up to 17 courses of consolidation therapy including decitabine. RESULTS: Forty of 59 evaluable patients responded (66%). Complete remission rate was 58%. Median relapse-free survival (RFS) was 14.1 (95% confidence interval [CI], 6.9 to not estimable), and median overall survival (OS) was 12.7 months (95% CI, 8.8 to not estimable). Median OS of responding patients (complete response [CR]/CR with platelet count <100 × 109/L) was 24.2 months (95% CI, 17 to not estimable). Compared with a historical group of patients who received clofarabine plus low-dose cytarabine with a shorter consolidation, RFS was not statistically different. Induction mortality was low (7% at 8 weeks) and toxicities manageable. CONCLUSIONS: Clofarabine plus low-dose cytarabine alternating with decitabine in consolidation is active in older patients with newly diagnosed AML. The benefits of a prolonged consolidation remain unproven.

Phase I and extension study of clofarabine plus cyclophosphamide in patients with relapsed/refractory acute lymphoblastic leukemia.

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.

Preclinical and early clinical evaluation of the oral AKT inhibitor, MK-2206, for the treatment of acute myelogenous leukemia.

PURPOSE: Recent studies suggested that AKT activation might confer poor prognosis in acute myelogenous leukemia (AML), providing the rationale for therapeutic targeting of this signaling pathway. We, therefore, explored the preclinical and clinical anti-AML activity of an oral AKT inhibitor, MK-2206. Experimental Methods: We first studied the effects of MK-2206 in human AML cell lines and primary AML specimens in vitro. Subsequently, we conducted a phase II trial of MK-2206 (200 mg weekly) in adults requiring second salvage therapy for relapsed/refractory AML, and assessed target inhibition via reverse phase protein array (RPPA). RESULTS: In preclinical studies, MK-2206 dose-dependently inhibited growth and induced apoptosis in AML cell lines and primary AML blasts. We then treated 19 patients with MK-2206 but, among 18 evaluable participants, observed only 1 (95% confidence interval, 0%-17%) response (complete remission with incomplete platelet count recovery), leading to early study termination. The most common grade 3/4 drug-related toxicity was a pruritic rash in 6 of 18 patients. Nevertheless, despite the use of MK-2206 at maximum tolerated doses, RPPA analyses indicated only modest decreases in Ser473 AKT (median 28%; range, 12%-45%) and limited inhibition of downstream targets. CONCLUSIONS: Although preclinical activity of MK-2206 can be demonstrated, this inhibitor has insufficient clinical antileukemia activity when given alone at tolerated doses, and alternative approaches to block AKT signaling should be explored.

Augmented hyper-CVAD based on dose-intensified vincristine, dexamethasone, and asparaginase in adult acute lymphoblastic leukemia salvage therapy.

The prognosis of adult patients with relapsed acute lymphoblastic leukemia (ALL) remains poor. Recent studies in adolescents and young adults reported better outcomes when therapy was intensified. Based on hyper-CVAD (cyclophosphamide/vincristine/doxorubicin/dexamethasone) as a backbone, we designed an augmented version with intensified doses of vincristine, dexamethasone, and asparaginase (L-asparaginase in the first 62 patients and pegaspargase in the remainder) starting from course 1. Ninety patients have been enrolled, with a median age of 34 years (range, 14-70 years). Most patients (78%) had pre-B ALL and were in first salvage (76%), with a first remission duration of 12.6 months (range, 1-78 months). Ten patients had primary refractory disease. Of 88 evaluable patients, 41 (47%) achieved complete remission (CR), with a median time to CR of 29 days (range, 18-80 days). Eight patients (9%) died within the first 30 days. Median CR duration, progression-free survival, and overall survival were 5, 6.2, and 6 months, respectively. Median overall survival of CR patients was 10.2 months (range, 1.4-69.5+ months). Twenty-eight patients (32%) proceeded to stem cell transplantation. Myelosuppression-associated complications were frequent. Pegaspargase was equally effective and easier to administer than L-asparaginase. Augmented hyper-CVAD may be suitable to be studied in younger adults with untreated ALL.