Induction chemotherapy followed by allogeneic bone marrow transplantation or aggressive consolidation chemotherapy in childhood acute myeloblastic leukemia. A prospective study from the French Society of Pediatric Hematology and Immunology (SHIP)

Diagnosis and management of acute myeloid leukemia in children and adolescents: recommendations from an international expert panel

Despite major improvements in outcome over the past decades, acute myeloid leukemia (AML) remains a life-threatening malignancy in children, with current survival rates of ∼70%. State-of-the-art recommendations in adult AML have recently been published in this journal by Döhner et al. The primary goal of an international expert panel of the International BFM Study Group AML Committee was to set standards for the management, diagnosis, response assessment, and treatment in childhood AML. This paper aims to discuss differences between childhood and adult AML, and to highlight recommendations that are specific to children. The particular relevance of new diagnostic and prognostic molecular markers in pediatric AML is presented. The general management of pediatric AML, the management of specific pediatric AML cohorts (such as infants) or subtypes of the disease occurring in children (such as Down syndrome related AML), as well as new therapeutic approaches, and the role of supportive care are discussed.

The role of matched sibling donor allogeneic stem cell transplantation in pediatric high-risk acute myeloid leukemia: results from the AML-BFM 98 study

BACKGROUND

The role of allogeneic stem cell transplantation in post-remission management of children with high-risk acute myeloid leukemia remains controversial. In the multi-center AML-BFM 98 study we prospectively evaluated the impact of allogeneic stem cell transplantation in children with high-risk acute myeloid leukemia in first complete remission.

DESIGN AND METHODS

HLA-typed patients with high-risk acute myeloid leukemia, who achieved first complete remission (n = 247), were included in this analysis. All patients received double induction and consolidation. Based on the availability of a matched-sibling donor, patients were allocated by genetic chance to allogeneic stem cell transplantation (n = 61) or chemotherapy-only (i.e. intensification and maintenance therapy; n = 186). The main analysis was done on an intention-to-treat basis according to this allocation.

RESULTS

Intention-to-treat analysis did not show a significantly different 5-year disease-free survival (49 ± 6% versus 45 ± 4%, P(log rank) = 0.44) or overall survival (68 ± 6% versus 57 ± 4%, P(log rank) = 0.17) between the matched-sibling donor and no-matched-sibling donor groups, whereas late adverse effects occurred more frequently after allogeneic stem cell transplantation (72.5% versus 31.8%, P(Fischer)<0.01). These results were confirmed by as-treated analysis corrected for the time until transplantation (5-year overall survival: 72 ± 8% versus 60 ± 4%, P(Mantel-Byar) 0.21). Subgroup analysis demonstrated improved survival rates for patients with 11q23 aberrations allocated to allogeneic stem cell transplantation (5-year overall survival: 94 ± 6% versus 52 ± 7%, P(log-rank) = 0.01; n = 18 versus 49) in contrast to patients without 11q23 aberrations (5-year overall survival: 58 ± 8% versus 55 ± 5%, P(log-rank) = 0.66).

CONCLUSIONS

Our analyses defined a genetic subgroup of children with high-risk acute myeloid leukemia who benefited from allogeneic stem cell transplantation in the prospective multi-center AML-BFM 98 study. For the remainder of the pediatric high-risk acute myeloid leukemia patients the prognosis was not improved by allogeneic stem cell transplantation, which was, however, associated with a higher rate of late sequelae.

Treatment of childhood acute myeloid leukemia

Childhood acute myeloid leukemia is rare, but accounts for a significant number of malignancy-related deaths in this age group. However, the prognosis has improved over past decades, and survival rates of 60% and above have been reported. Still, this implies that more than a third of children and adolescents die from this disease. Moreover, treatment is intensive, and quality of life and late effects are worrying issues. Therefore, there is a need for further improved treatment of pediatric acute myeloid leukemia. This review describes several important developments in this respect, such as improved diagnostics, prognostic factors, subgroup-directed and tailored treatment, and targeted therapy. In addition, background information is provided and current treatment strategies are described, as well as the late effects of treatment. Most groups now have risk-group adapted protocols, with allogeneic stem cell transplantation often being reserved for the higher risk group. Even in these cases, the benefit of stem cell transplantation has not been demonstrated beyond reasonable doubt with current high-intensive chemotherapy. Similarly, the use of cranial irradiation for CNS prophylaxis and maintenance treatment does not seem to be indicated in general. Subgroup-directed treatment has become a reality for acute myeloid leukemia in young children with Down's syndrome and in acute promyelocytic leukemia. In addition to tailoring therapy according to biologic features and especially monitoring treatment by measurements of minimal residual disease, targeted therapy for subgroups with activating mutations in receptor tyrosine kinases will further optimize the treatment of pediatric acute myeloid leukemia. Together with the development of many novel agents that have different mechanisms of action than the currently available anticancer agents, and improved supportive care, it is realistic that the prognosis of acute myeloid leukemia in children and adolescents will improve further in the next 5-10 years.

Allogeneic bone marrow transplantation for acute myeloblastic leukaemia in remission: risk factors for long-term morbidity and mortality

In this single-centre retrospective study, we analysed risk factors for nonrelapse long-term morbidity and mortality in patients with acute myeloblastic leukaemia (AML) who had undergone allogeneic transplantation. A total of 112 patients with de novo AML in first complete remission (CR1), n=90 or second complete remission (CR2, n=22) who received un-manipulated bone marrow grafts from human leukocyte antigen identical siblings between January 1985 and August 2000 were included. Of these, 97 patients alive and disease-free for at least 100 days after transplant were selected for the purpose of this long-term analysis. The use of an intensified conditioning regimen, Gram-negative bacteriaemia before transplantation, year of transplantation and number of pretransplant chemotherapy courses for patients in CR1 significantly affected the 7-year event-free survival which was 57%. 7-year transplant-related mortality TRM was 22%. Significant predictors for TRM were: bacterial infections before transplantation, major ABO blood group incompatibility, late severe bacterial infections, and chronic (graft-versus-host disease) GvHD. Predictive factors for late severe bacterial infections were infections before transplant, total body irradiation and GvHD. Incidence and risk factors for other late events including, chronic GvHD, late infections, osteonecrosis, cataract, endocrine- cardiac- and lung-complications, cancer and performance status at last follow-up were also studied. The analysis strongly suggests that the combination of pretransplant factors such as chemotherapy and conditioning, and posttransplant factors such as chronic GvHD had a major impact on late nonrelapse morbidity and mortality.

Minimising the long-term adverse effects of childhood leukaemia therapy

Malignancies in childhood occur with an incidence of 13-14 per 100,000 children under the age of 15 years. Acute lymphoblastic leukaemia with an incidence of 29% is the most common paediatric malignancy, whereas acute myeloid leukaemias account for about 5%. The treatment of acute leukaemias consists of sequential therapy cycles (induction, consolidation, intensification, maintenance therapy) with different cytostatic drugs over a time period of up to 1.5-3 years. Over the last 25 years of clinical trials, a significant rise in the rate of complete remissions as well as an increase in long-term survival has been achieved. Therefore, growing attention is now focused on the long-term effects of antileukaemic treatment. Several cytostatic drugs administered in the treatment of acute leukaemia in childhood are known to cause long-term adverse effects. Anthracyclines may induce chronic cardiotoxicity, alkylating agents are likely to cause gonadal damage and secondary malignancies and the use of glucocorticoids may cause osteonecrosis. Most of the long-term adverse effects have not been analysed systematically. Approaches to minimising long-term adverse effects without jeopardising outcome have included: the design of new drugs such as a liposomal formulation of anthracyclines, the development of anthracycline-derivates with lower toxicity, the development of cardioprotective agents or, more recently, the use of targeted therapy;alternative administration schedules like continuous infusion or timed sequential therapy; and risk group stratification by the monitoring of minimal residual disease. Several attempts have been made to minimise the cardiotoxicity of anthracyclines: decreasing concentrations delivered to the myocardium by either prolonging infusion time or using liposomal formulated anthracyclines or less cardiotoxic analogues, or the additional administration of cardioprotective agents. The advantage of these approaches is still controversial, but there are ongoing clinical trials to evaluate the long-term effects. The use of new diagnostic methods, such as diagnosis of minimal residual disease, which allow reduction or optimisation of dose, offer potential advantages compared with conventional treatment in terms of reducing the risk of severe long-term adverse effects. Most options for minimising long-term adverse effects have resulted from theoretical models and in vitro studies, but only some of the modalities such as the use of dexrazoxane, the continuous infusion of anthracyclines or timed sequential therapy, have been evaluated in prospective, randomised studies in patients. Future approaches to predict severe toxicity may be based upon pharmacogenetics and gene profiling.

Recent advances in pediatric acute lymphoblastic and myeloid leukemia

Acute leukemia is the most common form of childhood cancer and is the primary cause of cancer-related mortality in children. In the United approximately 3250 cases are diagnosed annually in children and adolescents younger than 20 years, of whom 2400 have acute lymphoblastic leukemia (ALL). Treatment results in childhood ALL continue to improve, and the expected current cure rates approach 75 to 80% of all children with ALL, including T-ALL and mature B-cell ALL, the two variants that, not too long ago, had a considerably poorer prognosis compared with the common form of BpALL. The most significant new development in the past 2 years has been the development of further evidence for fetal origin of childhood leukemias, and additional evidence to support the notion that postnatal events modulating the events of immune-mediated elimination of these leukemic clones play a major role in the eventual development of clinical disease. Other epidemiologic developments include (1) increased appreciation of the role of drug-metabolizing enzymes, both in determining the predisposition to leukemia and response to therapy; and (2) both clinical observations and gene expression studies seeming to identify a new approach to the evaluation and treatment of children with MLL (11q23) rearrangements. A most remarkable new development in the induction therapy of childhood leukemia and lymphoma in the United States is the use of urate oxidase for prevention of tumor lysis syndrome and the associated uric acid nephropathy. Drug resistance, determined either on leukemic blast cells in vitro or by studies of MRD, is being looked at critically in an effort to improve the treatment results further. Consolidation with HDMTX has gained wider popularity with the realization that effective CNS prophylaxis can be achieved with intrathecal therapy plus HDMTX for consolidation. In contrast to ALL, the progress in the therapy of acute myeloid leukemia (AML) lags behind, with cure rates of approximately 40 to 50%. There is no convincing evidence for substitution of daunorubicin with other anthracyclines, nor evidence for using high-dose cytarabine during induction in childhood AML. Rather, a 3 + 10 regimen with total daunorubicin 180 mg/m2 and cytarabine 100 to 200 mg/2 for 10 days appears to yield the best results. The most important component of the postremission chemotherapy continues to be several courses of high-dose cytarabine. The results from the MRC 10, LAME 89/91 studies and the recent BFM 93 trial with high-dose cytarabine and mitoxantrone suggest that there may be some benefit to including this combination in the postremission phase of AML. Despite these improvements in chemotherapy, allogeneic BMT from a matched family donor remains the best option for most patients (excluding Down syndrome, APL, and possibly those with inv16). Newer prognostic markers of interest include FLT3/ITD and minimal residual disease at the end of induction therapy.

[Contribution of antineoplastic biotherapy in the treatment of leukemia in children]

Improvements in the chemotherapeutic and transplant regimens have had a significant impact in improving survival rates for pediatric leukemia. However, there are still major problems to address including what options are available for patients with chemoresistant disease and what strategies are available to avoid toxicity associated with highly cytotoxic treatment regimens. Gene and immunotherapy protocols hold great promise. Using gene transfer of a marker gene, a number of biologic issues in the therapy of leukemia have been addressed. For example, by gene marking autologous bone marrow grafts it has been possible to demonstrate that infused marrow contributes to relapse in acute and chronic myeloid leukemias. In the allogeneic transplant setting, genetically modified T-cells have proven valuable for the prophylaxis and treatment of viral diseases and may have an important role in preventing or treating disease relapse. Gene transfer is also being used to modify tumor function, enhance immunogenicity, and confer drug-resistance to normal hematopoietic stem cells. With the continued scientific advancements in this field, gene therapy will almost certainly have a major impact on the treatment of pediatric leukemia in the future.