Prospective comparative study of bone marrow transplantation and postremission chemotherapy for childhood acute myelogenous leukemia. The Associazione Italiana Ematologia ed Oncologia Pediatrica Cooperative Group

Auto-hematopoietic stem cell transplantation or chemotherapy? Meta-analysis of clinical choice for AML

For patients with acute myeloid leukemia (AML) who are not candidates for allogeneic stem cell transplantation (SCT) or do not have a human leukocyte antigen (HLA)-matched donor, it is unclear whether autologous SCT (ASCT) has a better prognosis after the first complete response (CR1) compared to further chemotherapy treatment. A meta-analysis evaluating ASCT compared to further chemotherapy for AML patients in CR1 was performed. The Medline, Embase, Cochrane Controlled Trials Registry, Cochrane Library, Web of Science, and National Knowledge Infrastructure of China databases were searched for relevant literature as of May 26, 2023. Eligible studies included prospectively enrolled adults with AML and randomized first-time respondent patients who did not have a matched sibling donor. Fourteen randomized controlled trials were identified and included 4281 participants, of which 1499 patients received ASCT and 2782 underwent chemotherapy and continued follow-up. In patients with AML in CR1, a lower relapse rate was associated with ASCT compared to chemotherapy [odds ratio (OR) = 0.49, 95% confidence interval (CI) = 0.41-0.57]. Significant disease-free survival (DFS; OR = 1.37, 95% CI = 1.02-1.84) and relapse-free survival (RFS; OR = 2.78, 95% CI = 1.28-6.02) ASCT benefits were documented, and there was no difference in the overall survival (OS) when the studies were pooled (OR = 1.12, 95% CI = 0.85-1.48). The study results indicated that after the first remission, AML patients receiving autologous stem cell transplantation had higher DFS and RFS, similar OS, and lower relapse compared to patients undergoing chemotherapy treatment. This indicated that autologous stem cell transplantation may have a better prognosis.

Pediatric Autologous Hematopoietic Stem Cell Transplantation: Safety, Efficacy, and Patient Outcomes. Literature Review

Autologous stem cell transplantation (auto-HSCT) is a part of the therapeutic strategy for various oncohematological diseases. The auto-HSCT procedure enables hematological recovery after high-dose chemotherapy, otherwise not tolerable, by the infusion of autologous hematopoietic stem cells. Unlike allogeneic transplant (allo-HSCT), auto-HSCT has the advantage of lacking acute-graft-versus-host disease (GVHD) and prolonged immunosuppression, however, these advantages are counterbalanced by the absence of graft-versus-leukemia. Moreover, in hematological malignancies, the autologous hematopoietic stem cell source may be contaminated by neoplastic cells, leading to disease reappearance. In recent years, allogeneic transplant-related mortality (TRM) has progressively decreased, almost approaching auto-TRM, and many alternative donor sources are available for the majority of patients eligible for transplant procedures. In adults, the role of auto-HSCT compared to conventional chemotherapy (CT) in hematological malignancies has been well defined in many extended randomized trials; however, such trials are lacking in pediatric cohorts. Therefore, the role of auto-HSCT in pediatric oncohematology is limited, in both first- and second-line therapies and still remains to be defined. Nowadays, the accurate stratification in risk groups, according to the biological characteristics of the tumors and therapy response, and the introduction of new biological therapies, have to be taken into account in order to assign auto-HSCT a precise role in the therapeutic strategies, also considering that in the developmental age, auto-HSCT has a clear advantage over allo-HSCT, in terms of late sequelae, such as organ damage and second neoplasms. The purpose of this review is to report the results obtained with auto-HSCT in the different pediatric oncohematological diseases, focusing on the most significant literature data in the context of the various diseases and discussing this data in the light of the current therapeutic landscape.

Chemotherapy-free treatment for acute promyelocytic leukemia: the pediatric view of a revolutionary tale

The addition of all-trans retinoic acid (ATRA) to the standard anthracycline-base chemotherapy has revolutionized the treatment of acute promyelocytic leukemia (APL) over the last decades, becoming a model for precision medicine. The protocols based on the combination of ATRA and chemotherapy allowed obtaining excellent response rates both for children and adults. However, the persistence of anthracycline chemotherapy as a backbone was a matter of concern for both acute and long-term complications. Efforts in reducing anthracycline cumulative dose or even eliminating anthracycline have been pursued in more recent pediatric protocols thanks to the introduction of arsenic trioxide (ATO). The impressive results of the ATRA/ATO combinations led to the introduction of protocols completely chemotherapy-free for standard-risk adult patients as the standard of care, whereas pediatric chemo-free protocols are still currently under evaluation. In this Review, we will critically retrace the history of this unique revolution in precision medicine, discussing the peculiar advantages for pediatric patients with APL.

Hematopoietic stem cell transplantation in pediatric patients with acute myeloid leukemia without favorable cytogenetics

Intensified chemotherapy, HSCT, and supportive care improve the survival of pediatric patients with AML. However, no consensus has been reached regarding the role of HSCT in patients without favorable cytogenetics. We evaluated OS and EFS according to prognostic factors that affect clinical outcomes, including cytogenetics risk group, conditioning regimen, donor type, disease status at the time of HSCT, and number of chemotherapy cycles prior to HSCT in 65 pediatric patients with AML without favorable cytogenetics who underwent HSCT. Fifteen of the 65 patients died: three of TRM and 12 of disease-related mortality. The 5-year OS and EFS were 78.0% and 72.0%, respectively, and the 5-year cumulative relapse and TRM rates were 26.9% and 5.1%, respectively. Survival rates were not influenced by cytogenetic group (intermediated vs. poor), donor type (related vs. unrelated), transplant type (myeloablative vs. reduced-intensity conditioning), or number of pretransplant chemotherapy cycles (≤3 vs. >3 cycles). The low TRM rate and encouraging outcomes suggest that HSCT may be a feasible treatment for pediatric patients with AML without favorable cytogenetics.

Unmanipulated Haploidentical Hematopoietic Stem Cell Transplantation in First Complete Remission Can Abrogate the Poor Outcomes of Children with Acute Myeloid Leukemia Resistant to the First Course of Induction Chemotherapy

Allogeneic hematopoietic stem cell transplantation (HSCT) is an important therapy option for children with acute myeloid leukemia (AML) resistant to the first course of induction chemotherapy (IC_1st). We aimed to identify the efficacy of unmanipulated haploidentical HSCT (haplo-HSCT) in children with AML in the first complete remission and whether children resistant (IC_1st-resistant; n = 38) or sensitive (IC_1st-sensitive; n = 59) to the IC_1st can achieve comparable outcomes. The cumulative incidence of grades III to IV acute graft-versus-host disease (GVHD) and severe chronic GVHD was .0% versus 20.1% (P = .038) and 21.7% versus 13.2% (P = .238), respectively, for the IC_1st-resistant and IC_1st-sensitive groups. The 3-year cumulative incidence of relapse and nonrelapse mortality was 22.2% versus 7.6% (P = .061) and 5.3% versus 10.8% (P = .364), respectively, for the IC_1st-resistant and IC_1st-sensitive groups. The 3-year probability of overall survival and disease-free survival was 76.3% versus 83.0% (P = .657) and 72.5% versus 81.6% (P = .396), respectively, for the IC_1st-resistant and IC_1st-sensitive groups. Multivariate analysis failed to show significant differences in survival rates between the groups. Thus, our results show that unmanipulated haplo-HSCT may overcome the poor prognostic significance of IC_1st-resistance in children with AML, and it is valid as a postremission treatment for children with IC_1st-resistant AML lacking an HLA-matched donor.

FDG-PET/CT for Detection of Extramedullary Disease in 2 Pediatric Patients With AML

Positron emission tomography combined with computed tomography (PET/CT) is a promising diagnostic procedure for the detection of extramedullary disease (EMD) in acute myeloid leukemia. We studied 2 children with acute myeloid leukemia who underwent PET to assess for EMD at diagnosis as well as in remission. We detected 5 EMD lesions in 2 cases with PET, only 2 of which were detectable on clinical examination. Our cases show PET's increased sensitivity over physical examination alone in assessing and monitoring the extent of this disease.

Results of the AIEOP AML 2002/01 multicenter prospective trial for the treatment of children with acute myeloid leukemia

Risk-adapted therapy and broad use of HSCT resulted in a significant improvement in outcome. AUTO- or ALLO-HSCT in high-risk patients resulted in a cumulative incidence of leukemia relapse superimposable to that of SR.

Treatment of acute myeloid leukemia in children: experience from a tertiary care hematology centre in India

OBJECTIVE

To assess the treatment and outcome of children with acute myeloid leukemia. The Primary objectives were to assess remission rates, treatment related toxicity and disease free survival. Secondary objective was to assess prognostic factors associated with poor outcome.

METHODS

A retrospective analysis of all treated patients with acute myeloid leukemia, less than 18 year of age from Sept 2005 to Aug 2009 was done. Clinical laboratory, treatment and follow up records retrieved to calculate remission rate, treatment related toxicity, disease free survival and poor prognostic factors.

RESULTS

This analysis included thirty five patients (male : female; 23:12), twenty seven (77.1%) achieved remission after one 3 + 7 induction and seven required two inductions. High dose cytosine arabinoside consolidation was given in thirty one patients while one underwent allogenic stem cell transplantation. Two patients died during chemotherapy (TRM- 5.7%), two did not complete the therapy, seventeen relapsed (48.5%) with 80% of relapses occurring within first year of remission and no relapse occurred after 2 years. Fourteen patients are in remission (40%, follow up 5-54 months) and cumulative median disease free survival is of 13 months.

CONCLUSIONS

The present data suggests that 3 + 7 induction, followed by high dose cytarabine consolidation has low treatment related toxicity and resource utilization; however, relapse free survival is inferior to more intensive regimens, highlighting the need to intensify chemotherapy regimen once the treatment related mortality has been minimized.

Outcome for children treated for relapsed or refractory acute myelogenous leukemia (rAML): a Therapeutic Advances in Childhood Leukemia (TACL) Consortium study

BACKGROUND

Current event-free survival (EFS) rates for children with newly diagnosed acute myeloid leukemia (AML) approach 50-60%. We hypothesize that further improvements in survival are unlikely to be achieved with traditional approaches such as dose intensive chemotherapy or hematopoietic stem cell transplants, since these therapies have been rigorously explored in clinical trials. This report highlights efforts to assess the response rates and survival outcomes after first or greater relapse in children with AML.

PROCEDURE

We performed a retrospective cohort review of pediatric patients with relapsed and refractory AML (rAML) previously treated at TACL institutions between the years of 1995 and 2004. Data regarding disease characteristics at diagnosis and relapse, treatment response, and survival was collected on 99 patients and 164 medullary relapses or treatment failures.

RESULTS

The complete response (CR) rate following the second therapeutic attempt was 56 +/- 5%. CR rates following a third treatment attempt was 25 +/- 8% while 17 +/- 7% achieved CR following the fourth through sixth treatments. The 5-year disease-free survival in patients achieving CR following a second therapeutic attempt was 43 +/- 7%. The 5-year EFS and overall survival (OS) rates for all patients receiving a second treatment attempt was 24 +/- 5% and 29 +/- 5%, respectively.

CONCLUSIONS

This CR rate following a second therapeutic attempt and OS rate in patients with rAML is consistent with the literature. There are limited published data of CR rates for subsequent relapses. Our data can serve as a historical benchmark to compare outcomes of future therapeutic trials in rAML against traditional chemotherapy regimens.

High transcript level of FLT3 associated with high risk of relapse in pediatric acute myeloid leukemia

Identification of prognostic factors and risk-based post-remission therapy was proposed to improve the outcomes of acute myeloid leukemia (AML) and a mutation of FLT3 has been reported to be a risk factor, especially for pediatric patients. Recently, FLT3 expression level was implicated to have prognostic significance in adults, but little is known for childhood AML. To define the prognostic significance, transcript level of FLT3 was analyzed in 52 pediatric AML patients. The median copy number of FLT3 was 4.6x10(3) (40-5.9x10(7) copies)/1.0x10(6) GAPDH copy, and the relapse free survival of patients with high transcript level of FLT3 (>10(6) copy number) (0%) was significantly lower than that of the others (53.2%). High transcript level of FLT3 was associated with a markedly high risk of relapse. The development of new therapeutic scheme such as a frontline allogeneic stem cell transplantation or administration of FLT3 inhibitor is needed to improve outcomes.

Acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of leukemias that result from clonal transformation of hematopoietic precursors through the acquisition of chromosomal rearrangements and multiple gene mutations. As a result of highly collaborative clinical research by pediatric cooperative cancer groups worldwide, disease-free survival has improved significantly during the past 3 decades. Further improvements in outcomes of children who have AML probably will reflect continued progress in understanding the biology of AML and the concomitant development of new molecularly targeted agents for use in combination with conventional chemotherapy drugs.

Hematopoietic stem cell transplantation for leukemia

Leukemia represents the most common pediatric malignancy, accounting for approximately 30% of all cancers in children less than 20 years of age. Most children diagnosed with leukemia are cured without hematopoietic stem cell transplantation (HSCT), but for some high-risk subgroups, allogeneic HSCT plays an important role in their therapeutic approach. The characteristics of these high-risk subgroups and the role of HSCT in childhood leukemias are discussed.

Outcomes of patients who participate in randomized controlled trials compared to similar patients receiving similar interventions who do not participate

BACKGROUND

Some people believe that patients who take part in randomised controlled trials (RCTs) face risks that they would not face if they opted for non-trial treatment. Others think that trial participation is beneficial and the best way to ensure access to the most up-to-date physicians and treatments. This is an updated version of the original Cochrane review published in Issue 1, 2005.

OBJECTIVES

To assess the effects of patient participation in RCTs ('trial effects') independent both of the effects of the clinical treatments being compared ('treatment effects') and any differences between patients who participated in RCTs and those who did not. We aimed to compare similar patients receiving similar treatment inside and outside of RCTs.

SEARCH STRATEGY

In March 2007, we searched The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, The Cochrane Methodology Register, SciSearch and PsycINFO for potentially relevant studies. Our search yielded 7586 new references. In addition, we reviewed the reference lists of relevant articles.

SELECTION CRITERIA

Randomized studies and cohort studies with data on clinical outcomes of RCT participants and similar patients who received similar treatment outside of RCTs.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed studies for inclusion, assessed study quality and extracted data.

MAIN RESULTS

We identified 30 new non-randomized cohort studies (45 comparisons): no new RCTs were found. This update now includes five RCTs (yielding 6 comparisons) and 80 non-randomized cohort studies (130 comparisons), with 86,640 patients treated in RCTs and 57,205 patients treated outside RCTs. In the randomised studies, patients were invited to participate in an RCT or not; these comparisons provided limited information because of small sample sizes (a total of 412 patients) and the nature of the questions they addressed. When the results of RCTs and non-randomized cohorts that reported dichotomous outcomes were combined, there were 98 comparisons; there was also heterogeneity (P < 0.00001, I(2) = 42.2%) between studies. No statistical significant differences were found for 85 of the 98 comparisons. Eight comparisons reported statistically significant better outcomes for patients treated within RCTs, and five comparisons reported statistically significant worse outcomes for patients treated within RCTs. There was significant heterogeneity (P < 0.00001, I(2) = 58.2%) among the 38 continuous outcome comparisons. No statistically significant differences were found for 30 of the 38 comparisons. Three comparisons reported statistically significant better outcomes for patients treated within RCTs, and five comparisons reported statistically significant worse outcomes for patients treated within RCTs.

AUTHORS' CONCLUSIONS

This review indicates that participation in RCTs is associated with similar outcomes to receiving the same treatment outside RCTs. These results challenge the assertion that the results of RCTs are not applicable to usual practice.

Indications and donor selections for allogeneic stem cell transplantation in children with hematologic malignancies

Allogeneic stem cell transplantation (SCT) is the only curative approach for many patients with advanced or high-risk leukemia. Advances in supportive care and management of graft-versus-host disease have resulted in improvements in outcomes of related and unrelated donor SCT, creating controversies as to which strategy might be the optimal therapy for individual patients. This article discusses the indications and donor selection strategies for SCT in patients with malignant hematologic disease.

Acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of leukemias that result from clonal transformation of hematopoietic precursors through the acquisition of chromosomal rearrangements and multiple gene mutations. As a result of highly collaborative clinical research by pediatric cooperative cancer groups worldwide, disease-free survival has improved significantly during the past 3 decades. Further improvements in outcomes of children who have AML probably will reflect continued progress in understanding the biology of AML and the concomitant development of new molecularly targeted agents for use in combination with conventional chemotherapy drugs.

Extramedullary infiltrates of AML are associated with CD56 expression, 11q23 abnormalities and inferior clinical outcome

We evaluated the frequency and prognostic significance of extramedullary infiltrates (EMI) at presentation of acute myeloid leukemia (AML) in adult patients. Of 331 cases with de novo AML, 101(30.5%) had extramedullary infiltrates at diagnosis. The extramedullary manifestations included: lymphadenopathy, splenomegaly, hepatomegaly, gingival hypertrophy, skin infiltrates and involvement of central nervous system (CNS). Patients with EMI had a high initial WBC count and a high proportion of M4/M5 morphological variants. The complete remission rate (CR) with induction chemotherapy was lower in patients with EMI (P=0.0077) and their overall survival was also inferior (P=0.0017). Flow cytometric evaluation of the surface antigens expressed by the leukemic blasts for CD34, TdT, HLADR, CD7, CD19 and CD56 found that only CD56 expression was associated with EMI. The association of CD56 expression with lymphadenopathy was statistically significant (P=0.035). Abnormal karyotypes were found in 50.6% of patients with EMI and 49.7% of patients without EMI. Only 11q23 abnormalities were associated with specific sites of EMI; lymphadenopathy (P=0.0111) and gingival hypertrophy (P=0.0016). Our study of adult AML patients demonstrates that EMI at diagnosis is associated with CD56 expression by leukemic blasts, 11q23 karyotypic abnormalities, low complete remission rate and poor overall survival.

Autologous bone marrow transplantation for children with AML in first remission

In Children's cancer group (CCG) 2891, newly diagnosed patients with AML were randomized between standard and intensive timing induction therapies. Patients in first remission who lacked an HLA matched family donor were randomized between an autologous bone marrow transplantation (ABMT) where marrow was purged with 4 hydroperoxycyclophosphamide and consolidation chemotherapy. One hundred and thirty seven patients received an ABMT. Myeloid and platelet engraftment occurred at a median of 44 and 42 days, respectively. Disease-free survival (DFS), relapse-free survival and overall survival at 8 years post induction were 47% (95% confidence interval (CI): 38-55), 50% (CI: 42-59) and 55% (CI: 46-63), respectively. Multivariate analysis of DFS showed WBC <50 000/microl and having received intensively timed induction therapy were associated with improved DFS. Recipients who received intensive timed induction therapy and whose WBC was less than 50 000/microl had a DFS at 8 years of 62% (CI: 49-73). Conversely, recipients who received intensive timed induction therapy patients whose WBC was > or =50 000/microl had a DFS of 33% (CI: 17-50), P=0.003. The results confirm previous studies that ABMT is effective post remission therapy for pediatric patients with AML in first remission.

Outcomes of patients who participate in randomised controlled trials compared to similar patients receiving similar interventions who do not participate

BACKGROUND

Some people believe that patients who take part in randomised controlled trials (RCTs) face risks that they would not face if they opted for non-trial treatment. Others think that trial participation is beneficial and the best way to ensure access to the most up to date physicians and treatments.

OBJECTIVES

To assess the effects of patient participation in RCTs ('trial effects') independent both of the effects of the clinical treatments being compared ('treatment effects') and any differences between patients who participated in RCTs and those who did not.

SEARCH STRATEGY

In May 2001, we searched The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, The Cochrane Methodology Register, SciSearch and PsycINFO for potentially relevant studies. Our search yielded over 10,000 references. In addition, we reviewed the reference lists of relevant articles and wrote to over 250 investigators to try to obtain further information.

SELECTION CRITERIA

Randomised studies and cohort studies with data on clinical outcomes of RCT participants and similar patients who received similar treatment outside of RCTs.

DATA COLLECTION AND ANALYSIS

At least two reviewers independently assessed studies for inclusion, assessed study quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

We included five randomised studies (yielding 6 comparisons) and 50 non-randomised cohort studies (85 comparisons), with 31,140 patients treated in RCTs and 20,380 patients treated outside RCTs. In the randomised studies, patients were invited to participate in an RCT or not; these comparisons provided limited information because of small sample sizes (a total of 412 patients) and the nature of the questions they addressed. There was statistically significant heterogeneity (P < 0.002, I(2) = 36.2%) among the 73 dichotomous outcome comparisons; none of the potential explanatory factors we investigated helped to explain this heterogeneity. No statistically significant differences were found for 63 of the 73 comparisons. Eight comparisons reported statistically significant better outcomes for patients treated within RCTs, and two comparisons reported statistically significant worse outcomes for patients treated within RCTs. There were no statistically significant differences in heterogeneity (P = 0.53, I(2) = 0%) or in outcomes (SMD 0.01, 95% CI -0.10 to 0.12) of patients treated within and outside RCTs in the 18 comparisons which had used continuous outcomes.

AUTHORS' CONCLUSIONS

This review indicates that participation in RCTs is not associated with greater risks than receiving the same treatment outside RCTs. These results challenge the assertion that the results of RCTs are not applicable to usual practice.

Extramedullary infiltration at diagnosis and prognosis in children with acute myelogenous leukemia

BACKGROUND

Extramedullary infiltration (EMI) is an occasional clinical symptom in childhood acute myelogenous leukemia (AML), but there is considerable controversy regarding the prognostic significance of EMI in AML.

PROCEDURE

We evaluated the frequency and prognostic significance of EMI at diagnosis of AML in children.

RESULTS

Of 240 cases of de novo AML excluding children with Down syndrome and acute promyelocytic leukemia, 56 (23.3%) showed EMI at diagnosis. Patients with EMI had a higher initial WBC count and a higher proportion of M4/M5 morphological variants. The complete remission rate following induction chemotherapy was lower in patients with EMI. However, the overall survival and event-free survival did not differ between patients with and without EMI. A detailed analysis showed that patients with EMI with a WBC count at diagnosis of over 100 x 10(9)/L or infiltration into the central nervous system are likely to have a poor prognosis.

CONCLUSIONS

CNS leukemia and EMI together with a WBC count of >100 x 10(9)/L at diagnosis of AML are high risk factors for relapse, and alternative treatment approaches for patients with these characteristics should be explored.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of acute myeloid leukemia in children: an evidence-based review

Clinical research examining the role of hematopoietic stem cell transplantation (SCT) in the therapy of acute myeloid leukemia (AML) in children is presented and critically evaluated in this systematic evidence-based review. Specific criteria were used for searching the published literature and for grading the quality and strength of the evidence and the strength of the treatment recommendations. Treatment recommendations based on the evidence are presented in the table entitled "Summary of Treatment Recommendations Made by the Expert Panel for Pediatric Acute Myeloid Leukemia" and were reached unanimously by a panel of experts in AML. The identified priority areas of needed future research in pediatric AML include: What is the role of risk group stratification, including the role of cytogenetics, in selection of patients for allogeneic SCT, especially those in first CR? What is the appropriate timing and use of alternative donor SCT, given that matched unrelated donor SCT appears to yield outcomes equivalent to matched related donor SCT? What is the role of reduced intensity SCT (including the use of fludarabine-based preparative regimens) and/or other immunomodulatory approaches to maximize the graft-versus-leukemic effect? and What is the role of biologically targeted agents (ie, tyrosine kinase inhibitors, farnesyl transferase inhibitors, Flt-3 inhibitors, etc) in the treatment of AML, including induction, consolidation, conditioning regimens, and after SCT?

The outcome of children with acute myeloid leukemia (AML) post-allogeneic stem cell transplantation (SCT) is not improved by the addition of etoposide to the conditioning regimen

BACKGROUND

Relapse remains a concern for children with AML undergoing allogeneic SCT, so in an effort to reduce the risk of relapse in these patients, we intensified our pre-SCT preparation by adding etoposide to the standard busulfan and cyclophosphamide regimen.

PROCEDURE

We retrospectively analyzed the collected data and compared the two groups; Group A (n = 18) included patients who received busulfan 16 mg/kg plus cyclophosphamide 200 mg/kg (Bu/Cy), and Group B (n = 48) included patients who received busulfan 12 mg/kg, cyclophosphamide 90 mg/kg in addition to etoposide 60 mg/kg (Bu/Cy/VP). The patients' characteristics were similar in the two groups.

RESULTS

No significant difference in the overall outcome was noted; the 5-year overall survival was 50% and 53.3% for Groups A and B, respectively (P = 0.9). Similarly, the 5-year probability of relapse was 64.1% and 46.1% for Groups A and B, respectively (P = 0.38). The use of etoposide was not associated with increased toxicity.

CONCLUSION

The addition of etoposide to the Bu/Cy regimen was well tolerated, but did not appear to improve the outcome.

Emergence of antitumor cytolytic T cells is associated with maintenance of hematologic remission in children with acute myeloid leukemia

Although the graft-versus-leukemia effect of allogeneic bone marrow transplantation (BMT) is of paramount importance in the maintenance of disease remission, the role played by the autologous T-cell response in antitumor immune surveillance is less defined. We evaluated the emergence of antileukemia cytotoxic T-lymphocyte precursors (CTLp's) and the correlation of this phenomenon with maintenance of hematologic remission in 16 children with acute myeloid leukemia (AML), treated with either chemotherapy alone (5 patients) or with autologous BMT (A-BMT, 11 patients). Antileukemia CTLp's were detectable in 8 patients in remission after induction chemotherapy; none of them subsequently had a relapse. Of the 8 patients who did not show detectable CTLp frequency while in remission after induction chemotherapy, 7 subsequently experienced leukemia relapse. In patients undergoing A-BMT, molecular fingerprinting of the TCR-Vbeta repertoire, performed on antileukemia lines, demonstrated that selected antileukemia T-cell clonotypes, detectable in bone marrow before transplantation, survived ex vivo pharmacologic purging and were found in the recipient after A-BMT. These data provide evidence for an active role of autologous T cells in the maintenance of hematologic remission and also suggest that quantification of antileukemia CTLp frequency may be a useful tool to identify patients at high risk for relapse, thus potentially benefiting from an allogeneic antitumor effect.

Efficacy and tolerability of gemtuzumab ozogamicin (anti-CD33 monoclonal antibody, CMA-676, Mylotarg) in children with relapsed/refractory myeloid leukemia

BACKGROUND

Gemtuzumab ozogamicin (GO) is a cytotoxic anti-CD33 monoclonal antibody that has given promising preliminary results in adult myeloid CD33+ AML. We conducted a retrospective multicenter study of 12 children treated with GO on a compassionate basis (median age 5.5 y). Three patients (2 MDS/AML, 1 JMML) were refractory to first-line treatment, 8 patients with de novo AML were in refractory first relapse, and one patient with de novo AML was in 2nd relapse after stem cell transplantation (SCT). CD33 expression exceeded 20% in all cases.

METHODS

GO was administered alone, at a unit dose of 3-9 mg/m2, once (3 patients), twice (3 patients), three (5 patients) or five times (1 patient). Mean follow-up was 128 days (8-585 d).

RESULTS

There were three complete responses (25%) leading to further curative treatment (SCT). Treatment failed in the other nine patients, and only one patient was alive at the end of follow-up. NCI-CTC grade III/IV adverse events comprised hematological toxicity (n = 12), hypertransaminasemia (n = 2), allergy and hyperbilirubinemia (1 case each). There was only one major adverse event (grade IV allergy). No case of sinusoidal obstruction syndrome occurred.

CONCLUSION

These results warrant a prospective trial of GO in a larger population of children with AML.

Curing childhood acute myeloid leukemia (AML) at the half-way point: promises to keep and miles to go before we sleep

Childhood and adolescent acute myeloid leukemia (AML) is traditionally one of the hardest childhood cancers to successfully treat and had an overall survival well under 10% in the 1960s. Initial progress was made by three major events: (1) active chemotherapeutic agents were identified which led to remissions for the first time in this disease; (2) cooperative groups were instituted leading to important clinical trials; and (3) several single institutions began experimenting with the role of allogeneic matched sibling donor (MSD) BMT as effective intensification. Over the last 25 years, the cure rate has improved from <20% to 50% or higher. Most of the clinical research during this time of great advancement focused on two major themes: (1) the role of aggressive induction therapy in not only improving CR rates but in post-remission outcomes; and (2) the role of aggressive post-remission therapy in further improving survival, with an emphasis on high-dose Ara C-based chemotherapy, BMT, and supportive care. But we have "miles to go before we sleep." Some of the challenges that will lead to ongoing reduction of population-based mortality for AML through young adulthood include: (1) improving access of adolescents to pediatric AML therapy; (2) stratification by prognostic factors; (3) individualized therapy based on individual genetics and leukemia cell biology; (4) and the use of novel therapies including targeted immuno-conjugates and "small molecules" which disrupt abnormal signal transduction pathways. This brief review looks at both the advances over the last three decades as well as discusses the challenges moving forward for ultimately curing all children with this disease.

Treatment strategy and long-term results in paediatric patients treated in consecutive UK AML trials

Between 1988 and 2002, 758 children with acute myeloid leukaemia (AML) were treated on Medical Research Council (MRC) AML 10 and AML 12. MRC AML 10 tested the role of bone marrow transplantation following four blocks of intensive chemotherapy and found that while both allogeneic bone marrow transplant (allo-BMT) and autologous bone marrow transplant (A-BMT) significantly reduced the relapse risk (RR), this did not translate into a significant improvement in overall survival (OS). A risk group stratification based on cytogenetics and response to the first course of chemotherapy derived from MRC AML 10 was used to deliver risk-directed therapy in MRC AML 12. Allo-BMT was limited to standard and poor risk patients and A-BMT was not employed. Instead, the benefit of an additional block of treatment was tested by randomising children to receive either four or five blocks of treatment in total. While the results of MRC AML 12 remain immature, there appears to be no survival advantage for a fifth course of treatment. The 5 year OS, disease-free survival (DFS), event-free survival (EFS) and RR in MRC AML 12 are 66, 61, 56 and 35%, respectively; at present superior to MRC AML 10, which had a 5-year OS, DFS, EFS and RR of 58, 53, 49 and 42%, respectively. MRC AML trials employ a short course of triple intrathecal chemotherapy alone for CNS-directed treatment and CNS relapse is uncommon. Improvements in supportive care have contributed to improved outcomes and the number of deaths in remission fell between trials. Anthracycline-related cardiotoxicity remains a concern and the current MRC AML 15 trial tests the feasibility of reducing anthracycline dosage without compromising outcome by comparing standard MRC anthracycline-based consolidation with high-dose ara-C. MRC studies suggest that the role of allo-BMT is limited in 1st CR and that there may be a ceiling of benefit from current or conventional chemotherapy.

Treatment and long-term results in children with acute myeloid leukaemia treated according to the AIEOP AML protocols

Since 1982, four consecutive studies on childhood acute myeloid leukaemia (AML) (namely LAM-82, -87, -87M and -92) have been conducted in Italy by the Associazione Italiana di Ematologia e Oncologia Pediatrica (AIEOP) group. The induction therapy of the first three studies consisted of daunorubicin and cytarabine structured in a 3+7 backbone. In the most recent protocol (LAM92), patients received two induction courses including idarubicin, cytarabine and etoposide. Patients with acute promyelocytic leukaemia (20% of diagnoses) were included in LAM-87 and 87M studies. Postremissional therapy significantly changed over time, with an ever-increasing role given to stem cell transplantation (SCT). The long-term outcome of patients enrolled in the LAM-82, 87 and 87M studies was comparable, whereas that of children treated according to LAM-92 study was significantly better (P<0.005). Either allogeneic or autologous SCT was employed as consolidation therapy in more than 75% of cases enrolled in this latter study. Patients enrolled in the LAM-92 study were stratified in standard and high-risk groups with different outcome (67 vs 47%, respectively, P=0.04). Altogether, the results obtained in these four studies have permitted a progressive refinement of treatment, contributing to the structure of the ongoing LAM-2002 protocol that stratifies patients according to the presence of definite genetic anomalies and response to induction therapy.

Stem cell transplantation as consolidation therapy for children in first-remission AML: a single-center report

A large number of patients affected by acute myeloid leukemia (AML) achieve complete remission following induction chemotherapy based on high-dose aracytin and anthracyclines. However, a postremission consolidation treatment appears to be essential to maintain the remission status. Sixteen patients with newly diagnosed AML received induction chemotherapy according to the AIEOP LAM 92P/Mod protocol. All patients were HLA-typed, and if no donor was identified within the family, patients underwent autologous stem cell transplantation (autoSCT) with mafosfamide-purged bone marrow. Patients with very high-risk AML (cytogenetics with t(9;22), hyperleukocytosis (540x10(9)/L), and AML-M7 with trilineage myelodysplasia) underwent unrelated donor transplantation. One patient relapsed before autoSCT. Eleven patients underwent autoSCT with purged bone marrow, 3 patients underwent unrelated donor transplantation (UD), and 1 patient underwent HLA-identical, matched familiar donor transplantation (MFD). All patients achieved complete remission following one course. No treatment-related deaths occurred during first-line treatment. The median interval between diagnosis and transplant was 175 days (129-277). Three patients relapsed following autoSCT; none relapsed after alloSCT. Taking stem cell transplantation as the starting point, overall survival was 93%, disease-free survival (according to the chosen treatment) was 80%, the relapse rate was 20%, and transplant-related mortality was 0%.

Treatment strategy and results in children treated on three Dutch Childhood Oncology Group acute myeloid leukemia trials

This report describes the long-term follow-up data of three consecutive Dutch Childhood Oncology Group acute myeloid leukemia (AML) protocols. A total of 303 children were diagnosed with AML, of whom 209 were eligible for this report. The first study was the AML-82 protocol. Results were inferior (5-year probability of overall survival (pOS) 31%) to other available regimes. Study AML-87 was based on the BFM-87 protocol, with prophylactic cranial irradiation in high-risk patients only, and without maintenance therapy. This led to a higher cumulative incidence of relapse than that reported by the Berlin-Frankfurt-Münster (BFM), but survival was similar (5-year pOS 47%), suggesting successful retrieval at relapse. The subsequent study AML-92/94 consisted of a modified BFM-93 protocol, that is, without maintenance therapy and prophylactic cranial irradiation. However, all patients were to be transplanted (auto- or allogeneic), although compliance was poor. Antileukemic efficacy was offset by an increase in the cumulative incidence of nonrelapse mortality, especially in remission patients, and survival did not improve (5-year pOS 44%). Our results demonstrate that outcome in childhood AML is still unsatisfactory, and that further intensification of therapy carries the risk of enhanced toxicity. Our patients are currently included in the MRC AML studies, based on the results of their AML 10 trial.

Bloodstream infections and invasive mycoses in children undergoing acute leukaemia treatment: A 13-year experience at a single Italian institution

The incidence rate (IR) of bloodstream infections (BI) and invasive mycoses (IM) during chemotherapy for paediatric acute lymphoblastic (ALL) or non-lymphoblastic leukaemias (AnLL) was evaluated for 153 BI and 22 IM diagnosed during 143,668 patient-days at risk from January 1988 to December 2000. IR, the number of episodes/100 days at risk, was 0.315 for AnLL and 0.092 for ALL (P < 0.001) with significant changes reflecting the intensity of anti-ALL chemotherapy. IR was 0.097 for first-line less intensive, 0.136 during first-line intensive, 0.261 during second-line therapy (P < 0.001), and 0.021 during maintenance. During intensive chemotherapy, the IR for BI was 0.134 in ALL with 0.087 for first-line less intensive therapy, 0.110 for first-line intensive, 0.230 for second-line intensive therapy (P < 0.001) and 0.274 in AnLL (P = 0.001). IR was 0.021 in ALL and 0.048 in AnLL (P = 0.034) for IM. In conclusion, there is a correlation between intensity of chemotherapy and rate of infections in paediatric acute leukaemias.

Allogeneic versus autologous versus peripheral stem cell transplantation in CR1 pediatric AML patients: a single center experience

BACKGROUND

Treatment of childhood acute myelocytic leukemia (AML) in first remission, is still evolving. Allogeneic bone marrow transplantation (BMT) in patients with a donor has been well established, but the role of autologous transplantation remains of interest, particularly in the light of some encouraging results in adults.

PROCEDURE

Out of 81 pediatric patients with AML in first CR, 67 were biologically randomized for allogeneic (n = 31), autologous (n = 20), or peripheral stem cell transplant (n = 16) after completing consolidation treatment, with the remaining (n = 11) dropping out or receiving chemotherapy. Disease free survival (DFS) of these different groups were analyzed.

RESULTS

Allogeneic transplantation is not superior to autologous and autologous peripheral blood stem cell transplantation (PBSCT) (DFS in 5 years is 61%, 50%, and 75%). The 5 years DFS in the autologous PBSCT group is significantly better than in the autologous BMT group (75% vs. 50%, P < 0.05).

CONCLUSION

In pediatric AML patients without a donor, autologous BMT or autologous PBSCT appears to be an effective treatment option with low transplant related mortality especially in less privileged countries where the chemotherapy only results are still low.

Outcome of allogeneic bone marrow transplantation for children with advanced acute myeloid leukemia

Allogeneic bone marrow transplantation (BMT) may offer the only chance of cure for children with acute myeloid leukemia (AML) in second complete remission (CR2) or with relapsed disease, but the outcome of these patients has not been clearly defined. We conducted a retrospective study of 58 children, median age 7.4 years (range 0.8-17.3), who received matched related or unrelated BMT at our institution for AML in CR2 (n = 12), in untreated first relapse (n = 11) or with refractory disease (n = 35), to identify risk factors associated with disease-free survival (DFS). Life threatening to fatal regimen-related toxicity was observed in 22% of patients. Estimates of DFS at 5 years (95% confidence interval) for patients in CR2, with untreated first relapse and refractory disease were 58% (27-80%), 36% (11-63%) and 9% (2-21%), respectively. Non-relapse mortality estimates were 0%, 27% (0-54%) and 17% (5-30%), and relapse estimates were 42% (14-70%), 36% (8-65%) and 74% (60-89%), respectively. Advanced disease phase and cytogenetic abnormalities at the time of transplantation were each associated with decreased DFS and increased relapse in multivariable regression models. Survival for children transplanted in CR2 or untreated first relapse is higher than that previously reported, but relapse remains the major cause of treatment failure regardless of disease stage.

Prognostic significance of FLT3 mutations in pediatric non-promyelocytic acute myeloid leukemia

FLT3 is a receptor tyrosine kinase involved in the survival of hematopoietic stem cells, and mutations of FLT3 have been reported to be of prognostic significance. This is the first study of FLT3 mutations in pediatric non-promyelocytic AML patients that received the same treatment scheme in single institute. FLT3 internal tandem duplication of the juxtamembrane domain (FLT3/ITD) and a point mutation in the tyrosine kinase domain (FLT3/TKD) were analyzed in 61 patients by PCR of genomic DNA. The incidence of FLT/ITD and FLT/TKD were 6.6% (4/61) and 3.3% (2/61), respectively. Patients with FLT3/TKD remain alive after autologous stem cell transplantation. The disease-free survival (DFS) of patients with FLT3/ITD (0%) was significantly lower than that of the others (52%). FLT3/ITD was the sole adverse prognostic factor for DFS by multivariate analysis (RR=5.6). Patients with FLT3/ITD relapsed early after complete remission even after receiving bone marrow transplantation from a matched related donor with little BuCy conditioning. New therapeutic scheme such as stem cell transplantation with more intensive conditioning just after complete remission could be applied in pediatric non-promyelocytic AML patients with the FLT3/ITD mutation.

Induction of apoptosis and effect on CD20+ using rituximab on autologous peripheral blood stem cell harvests from patients with B cell lymphomas

Purging of neoplastic cells for autologous stem cell transplantation is usually done in vivo by administering chemotherapy and/or other agents before harvesting. It is also possible to decrease malignant cells counts directly in the cell harvest. In this study, we ascertained the effect of anti-CD20 monoclonal antibody and rituximab administration on peripheral blood hematopoietic stem cells. Five samples of stem cell harvests from different patients with B cell lymphoma were obtained. Each sample was divided in two tubes with calcium gluconate (20 mEq/50 microl). Rituximab (1 mg/600,000 mononuclear cells) was added to one of the tubes. Using flow cytometry, CD19, CD20 (B cell markers), and CD95 (apoptosis marker), expression was measured at baseline and 24 h after the addition of rituximab. A one-sided t-test with equal variances was used to analyze the results. Immediately after rituximab addition, CD20 expression became null. No significant difference in variation of CD19 expression was detected after the addition of rituximab (-3.64% control vs. 0.63% rituximab, p = 0.69). Mean variations of percentage of CD95 expression were 2.9% (controls) and 10.52% (rituximab tubes) (p = 0.06). We conclude that rituximab is capable of initiating apoptosis in vitro. We found no decrease in the CD19+ cell count, used as a surrogate marker for CD20+ cells, meaning that, at least in 24 h, apoptosis activation is not capable of decreasing CD20+ cell numbers. In vitro purging of peripheral blood stem cells harvests with rituximab could be part of a broader therapeutic strategy to be offered to lymphoproliferative disorder patients.

Autologous stem cell transplantation using modified TAM or combination of triple-alkylating agents conditioning regimens as one of the post-remission treatments in patients with adult acute myeloid leukemia in first complete remission

A total of 174 newly diagnosed adult acute myeloid leukaemia (AML) patients were treated in first complete remission (CR1) using modified TAM or a combination of triple-alkylating agents followed by autologous transplantation (AT). Cytogenetic risk groups were classified and most patients received mobilized peripheral blood stem/progenitor cells (PBSCs). The infused cell dose consisted of a median of 4.1+/-2 (range, 1.2-17.1)x 10(6)/kg CD34+ cells. With a median follow-up of 51 months (range, 5-131 months) after CR1, the estimated 5-year disease-free survival (DFS) rate was 68 (95% confidence interval (CI), 63-73%) and the event-free survival rate at 5 years was 59 (95% CI, 54-64%). AML patients other than M3 subtype, the long-term DFS rate was 76, 33% for favourable and unfavourable risk groups, respectively. In all, 40 patients had relapses (40/174, 23%) at the median 15 months after CR1 (range, 8-66 months). Overall, seven patients (4%) died in connection with AT. The infused CD34+ cell dose (P=0.0389) was associated with survival by multivariate analysis. In conclusion, two novel conditioning regimens in AT are feasible for adults with variable risk AML followed for over a 10-year period.

Increasing mixed chimerism defines a high-risk group of childhood acute myelogenous leukemia patients after allogeneic stem cell transplantation where pre-emptive immunotherapy may be effective

Children with leukemias and increasing mixed chimerism (increasing MC) after allogeneic stem cell transplantation have the highest risk to relapse. Early immunological intervention was found to be effective in these cases. To substantiate this on a defined group of pediatric acute myelogenous leukemia (AML) patients, we performed serial analysis of post transplant chimerism and pre-emptive immunotherapy in patients with increasing MC. In total, 81 children were monitored, 62 patients revealed complete chimerism (CC), low-level MC or decreasing MC. Increasing MC was detected in 19 cases. Despite early immunological intervention relapse was still significantly more frequent in patients with increasing MC (9/19) than in patients with CC, low-level or decreasing MC (8/62, P<0.005). The probability of 3-year event-free survival (EFS) was 52% for all patients (n=81), 59% for patients with CC, low-level MC, 60% for patients with decreasing MC (n=62), and 28% for patients with increasing MC (n=19, P<0.005). Patients with increasing MC who received early immunological intervention showed a significantly enhanced probability for event-free survival (pEFS 36%, n=15) compared to patients with increasing MC without intervention (pEFS 0%, n=4, P<0.05). These results prove that pediatric AML patients with increasing MC are at highest risk for relapse and that early immunological intervention can prevent relapse in these patients.

Autologous peripheral blood stem cell transplantation with BCVAC conditioning in childhood acute myeloid leukemia

Autologous peripheral blood stem cell transplantation (APBSCT) after intensifying conditioning is one of the post-remission therapeutic options in childhood acute myeloid leukemia (AML) patients without a matched family donor, but the optimal conditioning regimen has not been defined. This study was performed to evaluate the efficacy of a novel conditioning regimen without busulfan or total body irradiation. In total, 28 children with AML underwent APBSCT with BCVAC (BCNU, etoposide, cytosine arabinoside and cyclophosphamide) conditioning regimen during first remission. The event-free survival rate was 71.43% for all patients and the only cause of treatment failure was relapse. Eight male patients recurred at 1-11 months (median 5 months) after APBSCT. One patient remains alive with salvage therapy after relapse. With the exception of fever, mucositis and diarrhea, no serious complications occurred during APBSCT, including veno-occlusive disease (VOD), and there was no transplantation-related mortality. One patient developed secondary MDS after APBSCT but recovered hematologically on medication. APBSCT with BCVAC conditioning was found to be a safe and effective alternative option for patients with childhood AML in first remission, without a matched family donor.

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.

Graft-versus-leukaemia effect in children: chronic GVHD has a significant impact on relapse and survival

To examine whether graft-versus-host-disease (GVHD) is associated with a graft-versus-leukaemia (GVL) effect that also influences the outcome of allogeneic stem cell transplantation (SCT) in childhood acute leukaemia, we evaluated all consecutive (n=169) children who had undergone SCT for ALL and AML at our centre. Median follow-up was 7 years. The 5-year probability of chronic GVHD was 34%. Median time to relapse was 24 months in children with chronic GVHD and 6 months in those without. The corresponding 5-year probabilities of relapse were 30 and 45% (P=0.01). The 5-year probability of survival was 54%. Patients with chronic GVHD had a significantly better survival, 77 vs 51% (P=0.01). In a Cox regression model, chronic GVHD independently decreased the risk of relapse (RR 0.44) and further predicted an increased chance of relapse-free survival (RR 1.7) and survival (RR 2.6). The impact of chronic GVHD on survival was most apparent in late-stage disease and in ALL. Acute GVHD was not an independent predictor for relapse or death in this study. This study is in support of a GVL effect in childhood leukaemia related to chronic GVHD, reducing the risk of relapse and improving survival.

Update in childhood acute myeloid leukemia: recent developments in the molecular basis of disease and novel therapies

Childhood acute myeloid leukemia is a heterogeneous group of disorders that remains challenging to treat. There are multiple common genetic alterations in childhood acute myeloid leukemia. These include chromosomal translocations affecting RUNX1-CBFbeta, RARalpha, and MLL. There are known activating mutations in the genes for the receptor tyrosine kinases FLT3, KIT, and FMS. As these abnormalities are better understood, they are providing important insights into the pathogenesis of disease as well as information about prognosis. Although intensive chemotherapy remains the mainstay of acute myeloid leukemia therapy, long-term cure rates with chemotherapy alone remain approximately 50%, creating an urgent need for better therapies. Multiple avenues are being explored in the design of new treatments for pediatric acute myeloid leukemia. Targeted therapies include targeted antibody therapy; inhibitors of FLT3, KIT, and farnesyltransferase; diphtheria toxin conjugated to the granulocyte-macrophage colony-stimulating factor; and antisense oligonucleotides. Another area of interest is chromatin remodeling and differentiation therapy, including agents such as all- retinoic acid, arsenic trioxide, and inhibitors of DNA methylation and histone deacetylation. There are also ongoing trials of antiangiogenesis agents. Another avenue for novel therapies is immunotherapy with agents such as interleukin-2 and tumor vaccines. This article reviews recent advances in understanding of the molecular basis for childhood acute myeloid leukemia and the design of novel therapies for the treatment of childhood acute myeloid leukemia.

Results of consecutive trials for children newly diagnosed with acute myeloid leukemia from the Australian and New Zealand Children's Cancer Study Group

Despite improvements in the treatment of acute myeloid leukemia (AML), approximately 50% of children die of the disease. Clinical trials in adult patients with AML indicate that idarubicin may have superior efficacy when compared to daunorubicin in the remission-induction phases of chemotherapy. We conducted consecutive clinical trials in children with newly diagnosed AML in which daunorubicin (group 1, n = 102) or idarubicin (group 2, n = 160) was used during the remission-induction (RI) and the early consolidation phases of chemotherapy. Idarubicin was given at a dose of either 10 mg/m(2) (group 2A, n = 106) or 12 mg/m(2) (group 2B, n = 53). A high rate of RI was achieved for all groups (95% group 1, 90% group 2A, 94% group 2B). There were no significant differences in 5-year event-free survival (EFS) or in overall survival (OS) when the 3 groups were compared (group 1: EFS 50%, OS 56%; group 2A: EFS 50%, OS 60%; group 2B: EFS 34%, OS 50%). RI deaths resulting from treatment toxicity were low-2% for group 1 and 5% for group 2. More gastrointestinal, pulmonary, and renal toxicity but fewer infections were observed in patients receiving idarubicin (P <.001, P =.04, P =.03, respectively). Following RI chemotherapy, all patients received 3 to 4 more courses of identical chemotherapy and then underwent either autologous (n = 156) or an allogeneic bone marrow transplantation (BMT) (n = 35). OS was higher in allogeneic BMT patients than in autologous BMT patients (79% vs 63%; P =.23). We conclude that daunorubicin is as effective as idarubicin for remission-induction therapy for childhood AML and has reduced toxicity.

The majority of children and adolescents with acute myeloid leukemia have detectable anti-DT388-GMCSF IgG concentrations, but at concentrations that should not preclude in vivo activity

PURPOSE

As a novel approach for the treatment of acute myeloid leukemia (AML), the authors are developing a fusion toxin (DT(388)-GMCSF) consisting of a truncated diphtheria toxin (DT(388)) linked to human granulocyte-macrophage colony-stimulating factor (GMCSF). A critical step in the development of DT(388)-GMCSF for clinical use in childhood and adolescent AML is to determine whether children and adolescents have preexisting antibodies to DT(388)-GMCSF due to childhood immunizations against diphtheria toxoid.

PATIENTS AND METHODS

Sera from 33 children and adolescents with AML and one with juvenile myelomonocytic leukemia were collected. The median age was 11.8 years. All scheduled diphtheria toxoid vaccinations were current except for the child diagnosed at 4 months of age. Anti-DT(388)-GMCSF antibody concentrations were detected by an enzymoimmunoassay and by an in vitro bioassay.

RESULTS

Thirty of 34 (88%) children and adolescents had detectable anti-DT(388)-GMCSF IgG antibody concentrations. The median concentration was 1.5 microg/mL, with a range from undetectable to 191.4 microg/mL. There was a positive correlation between the enzymoimmunoassay and bioassay. There was no difference between the anti-DT(388)-GMCSF IgG concentrations in these children and adolescents with AML and in 43 adults with AML. Preliminary results of the phase 1 trial of DT -GMCSF in adults with AML indicate that patients with baseline anti-DT(388)-GMCSF IgG concentrations of less than 2 microg/mL can achieve circulating DT(388)-GMCSF concentrations and can exhibit antileukemic activity. Twenty-three of 34 (67.6%) children and adolescents had anti-DT(388)-GMCSF IgG concentrations less than 2 microg/mL.

CONCLUSIONS

Despite routine diphtheria toxoid vaccinations, most children and adolescents with AML do not have anti-DT -GMCSF IgG concentrations that preclude in vivo activity of DT -GMCSF.

The value of allogeneic bone marrow transplant in patients with acute myeloid leukaemia at differing risk of relapse: results of the UK MRC AML 10 trial

Patients under 55 years in the United Kingdom Medical Research Council Acute Myeloid Leukaemia 10 trial who entered complete remission were tissue typed (n = 1063). Four hundred and nineteen had a matched sibling donor and 644 had no match. When compared on a donor versus no donor basis the relapse risk was reduced in the donor arm (36%vs 52%; P = 0.001) and the disease-free survival (DFS) improved (50%vs 42%; P = 0.01), but overall survival (OS) was not different (55%vs 50%; P = 0.1). Sixty-one per cent of patients with a donor underwent transplantation. When patients were subdivided into risk groups based on cytogenetics alone or with the addition of blast response to course 1, a reduction in relapse risk was seen in all risk groups and in three age cohorts (0-14, 15-34 and 35+ years). Significant benefit in DFS was only seen in the intermediate-risk cytogenetic group (50%vs 39%; P = 0.004). The OS benefit was only seen in intermediate-risk patients (55%vs 44%; P = 0.02). The reduction in relapse risk in good-risk patients was attributable to patients with t(15;17) and not to patients with t(8;21) or inv(16). Allogeneic transplantation given after intensive chemotherapy was able to reduce relapse in all risk and age groups. However, due to the competing effects of procedural mortality and an inferior response to chemotherapy if relapse does occur, there was a survival advantage only in patients of intermediate risk. This trial found no survival advantage in children, patients over 35 years or good-risk disease.