High-dose cytosine arabinoside and amsacrine or mitoxantrone in relapsed and refractory acute myeloid leukaemia: a prospective randomized study

Relapsed Acute Myeloid Leukemia: Need for Innovative Treatment Strategies to Improve Outcome

Relapse continues to be a major hurdle in achieving cure in patients with acute myeloid leukemia (AML). The outcome after relapse is not uniform in all patients with AML and is dependent on several prognostic variables, including age, cytogenetics at initial diagnosis, duration of first complete remission, whether an allogeneic stem cell transplant was performed during first complete remission, and the presence of a number of molecular aberrations. Despite extensive research over the past several decades, there is no standard of care for treating patients with relapsed AML. This is possibly due to the accrual of patients with widely different disease profiles in most trials for relapsed AML. With increasing insights into the disease biology based on identification of pathogenic and aberrant molecular and cellular pathways, novel therapeutic strategies are emerging. Hopefully in the near future, we can improve the outcome of patients with relapsed AML with treatment strategies based on identification of specific targets and methods to overcome these aberrant processes.

Homoharringtonine in combination with cytarabine and aclarubicin in the treatment of refractory/relapsed acute myeloid leukemia: a single-center experience

To assess the efficacy and toxicity of HAA regimen (Homoharringtonine 4 mg/m(2)/day, days 1-3; cytarabine 150 mg/m(2)/day, days 1-7; aclarubicin 12 mg/m(2)/day, days 1-7) as a salvage therapy in the treatment of refractory and/or relapsed acute myeloid leukemia (AML), 46 patients with refractory and/or relapsed AML, median age 37 (16-65) years, participated in this clinical study. The median follow-up was 41 (10-86) months. Eighty percent of patients achieved complete remission (CR), and the first single course of re-induction HAA regimen resulted in CR rate of 76.1 %. The study protocol allowed two courses of induction. The CR rates of patients with favorable, intermediate and unfavorable cytogenetics were 90 %, 88.9 %, and 37.5 %, respectively. For all patients, the estimated 3-year overall survival (OS) rate was 42 %, and the estimated relapse free survival (RFS) at 3 years for the 36 CR cases was 49 %. The toxicities associated with HAA regimen were acceptable. HAA is a good choice in cases with refractory/relapsing AML for salvage chemotherapy, preferably with a high-efficacy and low-toxicity profile.

Current and emerging therapies for acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a clonal disease characterized by the proliferation and accumulation of myeloid progenitor cells in the bone marrow, which ultimately leads to hematopoietic failure. The incidence of AML increases with age, and older patients typically have worse treatment outcomes than do younger patients.

OBJECTIVE

This review is focused on current and emerging treatment strategies for nonpromyelocytic AML in patients aged <60 years.

METHODS

A literature review was conducted of the PubMed database for articles published in English. Publications from 1990 through March 2009 were scrutinized, and the search was updated on August 26, 2009. The search terms used were: acute myeloid leukemia in conjunction with treatment, chemotherapy, stem cell transplantation, and immunotherapy. Clinical trials including adults with AML aged > or =19 years were selected for analysis. Conference proceedings from the previous 5 years of The American Society of Hematology, The European Hematology Association, and The American Society for Blood and Marrow Transplantation were searched manually. Additional relevant publications were obtained by reviewing the references from the chosen articles.

RESULTS

Cytarabine (AraC) is the cornerstone of induction therapy and consolidation therapy for AML. A standard form of induction therapy consists of AraC (100-200 mg/m(2)), administered by a continuous infusion for 7 days, combined with an anthracycline, administered intravenously for 3 days. Consolidation therapy comprises treatment with additional courses of intensive chemotherapy after the patient has achieved a complete remission (CR), usually with higher doses of the same drugs as were used during the induction period. High-dose AraC (2-3 g/m(2)) is now a standard consolidation therapy for patients aged <60 years. Despite substantial progress in the treatment of newly diagnosed AML, 20% to 40% of patients do not achieve remission with the standard induction chemotherapy, and 50% to 70% of first CR patients are expected to relapse within 3 years. The optimum strategy at the time of relapse, or for patients with the resistant disease, remains uncertain. Allogeneic stem cell transplantation has been established as the most effective form of antileukemic therapy in patients with AML in first or subsequent remission. New drugs are being evaluated in clinical studies, including immunotoxins, monoclonal antibodies, nucleoside analogues, hypomethylating agents, farnesyltransferase inhibitors, alkylating agents, FMS-like tyrosine kinase 3 inhibitors, and multidrug-resistant modulators. However, determining the success of these treatment strategies ultimately requires well-designed clinical trials, based on stratification of the patient risk, knowledge of the individual disease, and the drug's performance status.

CONCLUSIONS

Combinations of AraC and anthracyclines are still the mainstay of induction therapy, and use of high-dose AraC is now a standard consolidation therapy in AML patients aged <60 years. Although several new agents have shown promise in treating AML, it is unlikely that these agents will be curative when administered as monotherapy; it is more likely that they will be used in combination with other new agents or with conventional therapy.

Stem cell transplantation after salvage therapy with high-dose cytarabine and amsacrine in adults with high-risk leukaemia

Stem cell transplantation (SCT) may be the only curative option for patients with relapsed or refractory leukaemia, that is, high-risk (HR) leukaemia. Several salvage regimens have been used to cytoreduce disease before SCT, but disease progression or treatment toxicity limits numbers of patients receiving SCT. Here, we report our experience with high-dose cytarabine and amsacrine (Ara-amsa) to salvage patients with HR-leukaemia in the context of SCT. A total of 34 patients with HR-leukaemia (20 AML, 12 ALL, two advanced CML) received 3 g/m(2)/day cytarabine for 5 days and amsacrine 200 mg/m(2)/day for 3 days. Disease response was observed in 62% of patients. Toxicity was limited to neutropenic fever, one patient developed cerebellar toxicity and there was one treatment-related death. A total of 17 patients proceeded to SCT (12 allografts and five autografts). Median survival (OS) of all patients was 10.8 months (95% CI 7.8-21). Patients who were consolidated with SCT after salvage therapy had a superior median OS of 29.4 months (95% CI 12.5-upper limit not reached, n=17) than those who did not receive SCT (6.7 months, CI 1.5-8.6, P<0.0001). Median disease-free survival with SCT (23 months) was higher than after treatment with salvage chemotherapy alone (6.7 months, P=0.0002). Thus Ara-amsa can be used effectively to salvage HR-leukaemia, enabling further consolidation with SCT.

The treatment of acute myeloid leukemia in first relapse: a comprehensive review of the literature

Twenty years of published literature was reviewed for chemotherapy regimens used to treat patients with acute myeloid leukemia (AML) in first relapse. Thirty-one trials containing at least 20 patients in first relapse and information on patient age, duration of first complete remission (CR1), and rate of second complete remission (CR2) were analyzed. These trials included 10 retrospective studies with CR2 rates ranging from 30 to 64%, two phase II single-agent studies with CR2 rates of 8 and 25%, 15 phase II combination-agent studies with CR2 rates ranging from 14 to 87%, and four phase III randomized studies with CR2 rates ranging from 40 to 89%. When reported, median duration of CR2 was < or = 14 months and overall median survival was < or = 12 months. The probability of 3-year survival ranged from 8 to 29%. Combination therapies resulted in higher CR2 rates but were associated with longer duration of myelosuppression and greater incidence of mucositis. None of the reviewed regimens provided durable remissions for the majority of AML patients in first relapse. The CR2 rates were closely associated with age and duration of CR1. Therefore, considering the poor clinical outcomes of patients with AML in first relapse, improved therapies need to be developed.

Multivariate analysis of prognostic factors in patients with refractory and relapsed acute myeloid leukemia undergoing sequential high-dose cytosine arabinoside and mitoxantrone (S-HAM) salvage therapy: relevance of cytogenetic abnormalities

To improve the basis for the stratification of patients with refractory and relapsed acute myeloid leukemia (AML) univariate and multivariate analyses of prognostic factors were performed in 254 patients (median age 50 years, range 18-74) undergoing S-HAM salvage chemotherapy during two consecutive prospective trials of the German AML Cooperative Group. In a multivariate analysis, duration of the first complete remission (CR) was the only factor associated with time to treatment failure (P = 0.0223). Disease-free survival was influenced by a short duration of the first CR of less than 6 months (P = 0.0001), WBC (P = 0.0018), blast count (P = 0.0037), and neutrophil count (P = 0.0119). The achievement of CR was related to the hemoglobin level only (P = 0.0457), the early death rate was related to age only (P = 0.0109), and survival was related to the bilirubin level only (P = 0.0166). In the subgroup of 104 patients in whom additional karyotype analyses were performed prior to first-line therapy unfavorable chromosome abnormalities were associated with a lower CR rate (univariate analysis, P = 0.0342; CR 24% vs 53%) and were the only factor related to survival. These analyses warrant the further evaluation of the impact of cytogenetic abnormalities on the outcome of patients with advanced AML in order to improve the characterization according to duration of first CR and to WBC of distinct subgroups of patients with differing prognoses as a basis for stratification in future trials.

Intensified induction chemotherapy with high dose cytarabine and etoposide for acute myeloid leukemia: a review and updated results of the Australian Leukemia Study Group

Induction therapy of acute myeloid leukemia (AML) with standard dose chemotherapy will result in approximately 55-75% of patients achieving a complete remission (CR). Intensification of induction treatment with etoposide and high dose cytarabine does not alter the CR rate but appears to significantly improve the subsequent outcome. Updated results of the comparison of high dose cytarabine with daunorubicin and etoposide in induction (HIDAC-3-7) versus a standard dose combination (7-3-7) demonstrated a highly significant increase in relapse free survival, (RFS) on the high dose arm (p = 0.007) with RFS of 48% at 5 years with HIDAC-3-7 and 25% on 7-3-7. The high dose arm had a more modest survival advantage at 5 years of 33% compared with 25% on standard treatment, possibly because of a higher initial death rate with HIDAC-3-7. The improvement seen in patients with CR after high dose induction appear to parallel results obtained with post-remission therapies intensified with high dose cytarabine. These studies provide clinical evidence that a dose-response effect is present for cytarabine in AML. Intensified treatment is more toxic, gives more profound myelosuppression post-remission and has been shown to benefit younger patients only. Issues of patient selection and the optimal placement of intensification in the treatment sequence require further study. In the future, it is likely that remission duration may be a useful clinical tool to study the influence of new induction therapies on residual resistant leukemia.

An effective age-unrestricted m-AMSA-based second-line regimen for poor prognosis acute myeloid leukaemia

The efficacy and toxicity of a regimen consisting of amsacrine (m-AMSA), cytarabine, and thioguanine for remission-induction therapy in poor prognosis categories of acute myeloid leukaemia (AML) were determined in a single arm study of 46 patients. The study group consisted of 17 patients with disease refractory to daunorubicin plus cytarabine-based induction regimens, 22 patients with disease which had relapsed during daunorubicin plus cytarabine maintenance therapy, or following completion of this maintenance programme after receiving > or = 500 mg daunorubicin/m2, and 7 previously untreated patients where cardiac disease contraindicated anthracycline therapy. Complete remission (CR) was attained in 46%, and probability of survival was comparable to published results for first-line treatment with daunorubicin plus cytarabine regimens. There was no statistically significant difference in CR rate or probability of survival between these three categories of poor prognosis AML, and cardiotoxic complications were uncommon despite extensive anthracycline exposure in the majority. In the 43% of patients who were 60-76 years of age, there was no statistically significant difference in CR rate or probability of survival relative to patients < 60 years. This observation fails to support the view that less myelotoxic regimens with lesser efficacy should be the basic approach to treatment of AML in patients > or = 60 years of age.

Phase-II study of treatment of refractory acute leukemia with intermediate-dose cytosine arabinoside and amsacrine

Twenty-five consecutive leukemia patients (21 AML, 4 ALL) with either primary resistance (n = 22) or resistant relapse (n = 3) of all FAB subtypes were treated with 1 or 2 cycles of ID-ara C (1 g/m2 i.v. q 12 h, days 1-6) and AMSA (120 mg/m2 i.v., days 5-7). Patients reaching CR received 1 cycle of intensive consolidation using ara C 3 g/m2 i.v. q 12 h, days 1-4 and AMSA 120 mg/m2 i.v., day 5. Two patients received an allograft thereafter and are still alive and in CCR. CR was achieved in 12/25 patients (48%), ten after 1 cycle of induction and two after 2 cycles; 10/22 patients with primary resistant disease reached CR, and 2/3 with resistant relapse. Nine patients remained refractory (36%) and four died during hypoplasia (16%). Median DFS of the 12 responders was 2.9 months, median survival from time of CR 8.9 months. Median overall survival of responders and nonresponders was 6 months from time of resistance. Survival advantage of responding patients (n = 12) as compared with nonresponders (n = 13) was 10.7 vs. 3.2 months (p = 0.002). Toxicity of chemotherapy was acceptable: one patient experienced pulmonary edema due to ara C; two patients developed life-threatening systemic fungal infections, one of whom died while in CR.

Chemotherapy with high-dose cytosine arabinoside and mitoxantrone for poor-prognosis myeloid leukemias

Forty-seven patients with poor-prognosis myeloid leukemias received induction therapy with high-dose cytosine arabinoside (HDara-C), 1.5-3.0g/m2 for 8-10 doses, and mitoxantrone (DHAD), 12-15 mg/m2 for 3 doses. Complete remissions were achieved in 21 [45%, 95% confidence interval (CI) 30.2-59.9%] of the patients, including 11 of 14 with acute myelogenous leukemia (AML) in first relapse (79%, 95% CI 49.2-95.3%), 4 of 8 with refractory anemia with excess blasts in transformation (RAEBiT) (50%, 95% CI 15.4-84.6%), and 4 of 6 (67%, 95% CI 22.3-95.7%) previously untreated elderly AML patients. Patients with secondary AML and advanced chronic myelogenous leukemia had a very low response rate. The incidence of reversible toxicity was low and only 3 treatment-related deaths occurred. After reinduction, 8 of 9 AML patients < or = 60 years of age were ultimately able to undergo intensive therapy and either autologous 4-hydroperoxycyclophosphamide-purged bone marrow (7 patients) or peripheral blood stem cell (1 patient) transplantation with satisfactory hematological recovery. We conclude that HDara-C and DHAD is an effective antileukemic regimen in selected AML and RAEBiT patients, and that its use may allow subsequent successful autologous BMT in appropriate patients.

High-dose cytosine arabinoside intensification for acute nonlymphocytic leukemia in patients over 56 years of age

One hundred and nine consecutive patients with de novo acute nonlymphocytic leukemia aged over 56 years were admitted with the intention of administering high-dose cytosine arabinoside (HD Ara-C) intensification. After remission induction, the patients were consolidated with a course of daunorubicin (30 mg/m2/day, days 1-3) and Ara-C (100 mg/m2/day, days 1-7), followed by the intensification (Ara-C, 2 g/m2/12 h, days 1-4). The planned induction course was not started in 13 patients because of cardiac failure or unsatisfactory general status. Remission was achieved in 55% (53/96) of the patients. Twenty-seven patients (28%) had refractory disease, seven died early during induction therapy, five died of hemorrhage and three of infection during the hypoplasia that followed induction treatment. Thirty-nine patients started consolidation and 32 had the planned intensification. In these last patients the 3-year leukemia-free survival (LFS) probability was 29% (SE, 8%). No patient died as a consequence of intensification. The relapse rate of the intensified patients did not differ from the relapse rate of those patients who did not receive the planned intensification (p = 0.12). The only pretreatment variables significantly associated with a better LFS were younger age (p = 0.02) and a low WBC at diagnosis (p = 0.04). For the whole patient group, the 3-year survival probability was 15% (SE, 4%). This study shows that elderly patients can tolerate HD Ara-C. The patients completing consolidation-intensification have a currently acceptable LFS. To what extent HD Ara-C contributed to the length of the remissions remains unclear.