Duration of first remission predicts remission rates and long-term survival in children with relapsed acute myelogenous leukemia

Navigating Treatment Options and Communication in Relapsed Pediatric AML

Despite improved outcomes in newly diagnosed pediatric AML, relapsed disease remains a therapeutic challenge. Factors contributing to slow progress in improving outcomes include inherent challenges in pediatric clinical trial accrual and the scarcity of novel targeted/immunotherapy agents available for pediatric development. This paradigm is changing, however, as international collaboration grows in parallel with the development of promising targeted agents. In this review, we discuss the therapeutic landscape of relapsed pediatric AML, including conventional chemotherapy, targeted therapies, and the challenges of drug approvals in this patient population. We highlight current efforts to improve communication among academia, industry, and regulatory authorities and discuss the importance of international collaboration to improve access to new therapies. Among the therapeutic options, we highlight the approach to second hematopoietic stem cell transplant (HSCT) and discuss which patients are most likely to benefit from this potentially curative intervention. Importantly, we acknowledge the challenges in providing these high-risk interventions to our patients and their families and the importance of shared communication and decision making when considering early-phase clinical trials and second HSCT.

Single-dose (4.5 mg/m2 ) gemtuzumab ozogamicin in combination with fludarabine, cytarabine and anthracycline as reinduction therapy in relapsed or refractory paediatric acute myeloid leukaemia

Despite major therapeutic improvements, children with relapsed/refractory Acute Myeloid Leukaemia still have poor outcomes and overall survival does not exceed 40%. New treatments are required to improve their outcome; Gemtuzumab ozogamicin (GO), an anti-CD33 immunoconjugate antibody, is a potent cytotoxic agent whose efficacy has been demonstrated mainly in adults. The main objective of this retrospective multicentre study was to assess the outcome of children treated, between February 2008 and August 2019, with GO at a single 4.5 mg/m² dose, in combination with Fludarabine, Cytarabine and antssshracyclines, in context of a first relapse (n = 26) or refractory disease (n = 3). The remission rate was 83% (24/29 children) and 20 children (69%) were allografted. With a median follow-up of 1.2 years (range: 0.1-8), the overall survival was 49% (CI95% = 33; 72). Most common adverse event was febrile neutropenia with microbiological identification in 55% of cases. Veno-occlusive disease occurred in 6 patients (21%), of which 5 subvened after bone marrow transplantation, and resolved within 2-32 days (median 10.5 days). Administration of GO in combination with FLA-anthracyclines chemotherapy appears to be a good reinduction regimen for relapsed or refractory AML with a good safety profile. These results warrant larger prospective study.

Autologous Hematopoietic Stem Cell Transplant: A Potential Option for Relapsed Pediatric Acute Myeloid Leukemia With Lack of Matched Sibling Donor and Resource Challenge

Though allogeneic hematopoietic stem cell transplant (HSCT) is standard for relapsed pediatric acute myeloid leukemia, often it may not be accessible due to donor unavailability and resource limitations. We retrospectively analyzed outcomes of 26 children (mean age: 10.9±4.5 y) who underwent autologous HSCT in complete remission 2. Three-year event-free survival and overall survival were 50.1±10.7% and 63.3±9%, respectively; with 1 treatment-related death and 46% relapse rate. Notwithstanding the retrospective study design and somewhat favorable patient characteristics, the outcomes are comparable with those of other series and our own allogeneic HSCT data. Autologous HSCT is a potential alternative to allogeneic HSCT, especially in countries with poorly maintained donor registries.

Survival Following Relapse in Children with Acute Myeloid Leukemia: A Report from AML-BFM and COG

Simple Summary

Acute myeloid leukemia in children remains a difficult disease to cure despite intensive therapies that push the limits of tolerability. Though the intent of initial therapy should be the prevention of relapse, about 30% of all patients experience a relapse. Hence, relapse therapy remains critically important for survival. This retrospective analysis of two large international study groups (COG and BFM) was undertaken to describe the current survival, response rates and clinical features that predict outcomes. We demonstrate that children with relapsed AML may be cured with cytotoxic therapy followed by HSCT. High-risk features at initial diagnosis and early relapse remain prognostic for post-relapse survival. Current response criteria are not aligned with the standards of care for children, nor are the count recovery thresholds meaningful for prognosis in children with relapsed AML. Our data provide a new baseline for future treatment planning and will allow an updated stratification in upcoming studies.

Abstract

Post-relapse therapy remains critical for survival in children with acute myeloid leukemia (AML). We evaluated survival, response and prognostic variables following relapse in independent cooperative group studies conducted by COG and the population-based AML-BFM study group. BFM included 197 patients who relapsed after closure of the last I-BFM relapse trial until 2017, while COG included 852 patients who relapsed on the last Phase 3 trials (AAML0531, AAML1031). Overall survival at 5 years (OS) was 42 ± 4% (BFM) and 35 ± 2% (COG). Initial high-risk features (BFM 32 ± 6%, COG 26 ± 4%) and short time to relapse (BFM 29 ± 4%, COG 25 ± 2%) predicted diminished survival. In the BFM dataset, there was no difference in OS for patients who had a complete remission with full hematopoietic recovery (CR) following post-relapse re-induction compared to those with partial neutrophil and platelet recovery (CRp and CRi) only (52 ± 7% vs. 63 ± 10%, p = 0.39). Among 90 patients alive at last follow-up, 87 had received a post-relapse hematopoietic stem cell transplant (HSCT). OS for patients with post-relapse HSCT was 54 ± 4%. In conclusion, initial high-risk features and early relapse remain prognostic. Response assessment with full hematopoietic recovery following initial relapse therapy does not predict survival. These data indicate the need for post-relapse risk stratification in future studies of relapse therapies.

Second Relapse of Pediatric Patients with Acute Myeloid Leukemia: A Report on Current Treatment Strategies and Outcome of the AML-BFM Study Group

Simple Summary

Children with acute myeloid leukemia (AML) experience high relapse rates of about 30%; still, survival rates following the first relapse are encouraging. Hence, it is critically important to examine the consequences of a second relapse; however, little is known about this subgroup of patients. This retrospective population-based analysis intends to describe response, survival and prognostic factors relevant for the survival of children with second relapse of AML. Treatment approaches include many different therapeutic regimens, including palliation and intensive treatment with curative intent (63% of the patients). Survival is poor; however, patients who respond to reinduction attempts can be rescued with subsequent hematopoietic stem cell transplantation. We deciphered risk factors, such as short time interval from first to second relapse below one year as being associated with a poor outcome. This analysis will help to improve future international treatment planning and patient care of children with advanced AML.

Abstract

Successful management of relapse is critical to improve outcomes of children with acute myeloid leukemia (AML). We evaluated response, survival and prognostic factors after a second relapse of AML. Among 1222 pediatric patients of the population-based AML-Berlin–Frankfurt–Munster (BFM) study group (2004 until 2017), 73 patients met the quality parameters for inclusion in this study. Central review of source documentation warranted the accuracy of reported data. Treatment approaches included palliation in 17 patients (23%), intensive therapy with curative intent (n = 46, 63%) and other regimens (n = 10). Twenty-five patients (35%) received hematopoietic stem cell transplantation (HSCT), 21 of whom (88%) had a prior HSCT. Survival was poor, with a five-year probability of overall survival (pOS) of 15 ± 4% and 31 ± 9% following HSCT (n = 25). Early second relapse (within one year after first relapse) was associated with dismal outcome (pOS 2 ± 2%, n = 44 vs. 33 ± 9%, n = 29; p < 0.0001). A third complete remission (CR) is required for survival: 31% (n = 14) of patients with intensive treatment achieved a third CR with a pOS of 36 ± 13%, while 28 patients (62%) were non-responders (pOS 7 ± 5%). In conclusion, survival is poor but possible, particularly after a late second relapse and an intensive chemotherapy followed by HSCT. This analysis provides a baseline for future treatment planning.

The outcomes of relapsed acute myeloid leukemia in children: Results from the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05R study

BACKGROUND

The prognosis of children with acute myeloid leukemia (AML) has improved with the efficacy of hematopoietic cell transplantation (HCT) as a second-line therapy and improvements in supportive care following anthracycline- and cytarabine-based chemotherapy; however, the outcomes of children with relapsed AML still remain unsatisfactory.

PROCEDURE

In order to identify prognostic factors and improve their prognosis, we analyzed 111 patients who relapsed after treatment with the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 protocol and who were registered in the retrospective JPLSG AML-05R study.

RESULTS

The 5-year overall survival rate was 36.1%. The major determinant of survival was duration from the diagnosis to relapse. The mean duration in the nonsurviving group (10.1 ± 4.1 months) was shorter than that in the surviving group (16.3 ± 8.3 months) (P < .01). Moreover, achieving a second complete remission (CR2) prior to HCT was associated with a good prognosis (P < .01). Etoposide, cytarabine, and mitoxantrone (ECM)- or fludarabine, cytarabine, and granulocyte colony-stimulating factor (FLAG)-based regimens were therefore recommended for reinduction therapy (P < .01). A genetic analysis also revealed the prognostic significance of FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication as a poor prognostic marker (P = .04) and core binding factor-AML, t(8;21), and inv(16) as good prognostic markers (P < .01).

CONCLUSIONS

Achieving a CR2 prior to HCT is important in order to improve the prognosis of relapsed pediatric AML. Recent molecular targeted therapies, such as FLT3 inhibitors, may contribute to overcome their prognoses. Larger prospective investigations are necessary to establish individualized treatment strategies for patients with relapsed childhood AML.

Pediatric relapsed acute myeloid leukemia: a systematic review

Introduction: Pediatric relapsed acute myeloid leukemia (AML) remains lethal in the majority of cases, despite intensive therapy. Randomized trials are largely lacking, and the main issues of optimal therapy and prognostic factors remain unclear. Area covered: This systematic review includes all literature evaluating treatment outcome after first relapse. We searched databases PubMed and Embase.com. Twelve out of six thousand articles were ultimately included, based on age of the population (<21 years), relapsed AML, and information on clinical outcome (second complete remission (CR2), disease-free survival (DFS), event-free survival (EFS) and overall survival (OS)). There was only one randomized clinical trial reported. This review shows that there is no standard treatment for relapsed AML in children, and that outcome varies for CR2 and (2- to 10-year) OS rates, mean 64% (range, 50-75%), and 31% (16-43%), respectively. Children treated with chemotherapy only in first complete remission (CR1) tend to have better outcome after relapse than children receiving allo-SCT in CR1. Allo-SCT seems to be the most effective consolidation therapy in children achieving CR2, after relapse. Duration of CR1 was the most frequently reported statistically significant prognostic factor. Through randomized clinical trials, better knowledge of prognostic factors enabling risk-stratified treatment, and of more effective and less toxic therapies, should contribute to better clinical outcome for children with relapsed AML. Expert opinion: Outcome of pediatric relapsed AML has improved to OS rates up to 40%. However, there is a lack of knowledge on (independent) prognostic factors, optimal reinduction chemotherapy, timing of allo-SCT, and late effects. International collaboration should enable large, randomized clinical trials addressing these issues.

Outpatient ADE (cytarabine, daunorubicin, and etoposide) is feasible and effective for the first relapse of pediatric acute myeloid leukemia: A prospective, phase II study

BACKGROUND

Approximately 40% children with acute myeloid leukemia (AML) invariably relapse, after attaining the first complete remission (CR), with dismal long-term outcome. There is little consensus regarding choice of optimal induction chemotherapy regimen for relapsed pediatric AML.

PROCEDURE

A prospective single arm phase II study (CTRI/2017/02/007757) was carried out at our center to evaluate the safety and efficacy of outpatient cytarabine, daunorubicin, and etoposide (ADE) regimen in pediatric AML (≤18 years) at the first relapse. Response evaluation was done by bone marrow aspiration morphology along with minimal residual disease (MRD) assessment. All adverse events including need and duration of hospitalization, transfusion support, and antimicrobial use were recorded.

RESULTS

Total 45 patients were included with median age of 12 years. The CR rate of the cohort was 66% and 54% of patients were MRD negative. The estimated 2-year event-free survival (EFS) and overall survival (OS) were 29% (±7%) and 34% (±7%), respectively. The presence of fever at relapse was associated with inferior CR rate (P = .001), positive MRD (P = .01), and inferior EFS (P = .02), while not achieving nadir absolute neutrophil count of zero during induction was associated with inferior CR rate (P = .03) and inferior OS (P = .04). Approximately all patients developed ≥Grade 3 cytopenia and febrile neutropenia. Twenty-six (59%) patients required hospitalization for management of toxicity and there were four (9%) deaths attributed to infection.

CONCLUSION

ADE is an effective induction regimen for pediatric AML patients at the first relapse with reasonable toxicity profile. Outpatient administration of the regimen is feasible in the presence of proper support structure and rigorous follow up.

Outcome of Childhood Acute Myeloid Leukemia With FLT3-ITD Mutation: The Experience of Children's Cancer Hospital Egypt, 2007-17

INTRODUCTION

The presence of FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) mutation in pediatric acute myeloid leukemia (AML) is associated with high rates of induction failure and worse survival. Its presence places the patient into a high-risk group. We aimed to describe the outcome of pediatric AML with FLT3-ITD mutation.

PATIENTS AND METHODS

We performed a retrospective analysis of cases of AML from July 2007 till July 2017 at Children's Cancer Hospital Egypt.

RESULTS

Seventy-one patients had FLT3 gene mutation out of 687 patients with AML. Sixty-five patients had FLT3 gene mutation with allelic ratio > 0.4; 43 (66.1%) of 65 patients experienced complete remission (CR). Of the 43 patients, 16 patients maintained CR, 18 patients relapsed after first CR, 8 patients died, and 1 patient was lost to follow-up. Patients with relapsing disease died after salvage chemotherapy, except for one patient, who was alive after second CR. Allogeneic bone marrow transplantation (allo-BMT) was performed for 9 (13.8%) of 65 patients in first CR, of whom 8 were alive and in CR, and 1 patient experienced disease relapse and died. Seven patients (10.7%) were alive without allo-BMT. Three years' overall and event-free survival for patients with FLT3-ITD mutation with high allelic ratio was 26.9% and 22.8%, respectively. Three years' overall and event-free survival for patients treated with allo-BMT was 77.8% and 78.8%, respectively, versus patients treated without allo-BMT, 16.3% and 12.8%, respectively.

CONCLUSION

FLT3-ITD mutation in pediatric AML was associated with poor treatment outcomes, and the survival of relapsing patients was extremely poor. Allo-BMT in first remission was the best treatment option. Alternative donor transplants and FLT3 inhibitors are needed to improve outcome in developing countries.

At three years, patients with acute lymphoblastic leukaemia are still at risk for relapse. Results of the international MRC UKALLXII/ECOG E2993 trial

Late relapse [>3 years from complete remission (CR)] in acute lymphoblastic leukaemia (ALL), is unusual. Data from the MRC UKALLXII/ECOG E2993 trial are presented to evaluate the incidence and characteristics of late relapse in adult ALL. Of 1,909 patients, 1,752 (92%) achieved CR and among these 757 (43·2%) relapsed; 691 (91·3%) within three years and 66 (8·7%) beyond. Among these 66 patients, median time to relapse was 47 (37–144) months. Relapse beyond three years occurred in 3·8% of all who achieved CR. The cumulative risk of relapse was 40%, 43% and 45% at three, five and ten years respectively. Out of the 1 752 patients who achieved CR, 11·7% underwent autologous and 40·6% allogeneic transplant, while in CR1. Of the autologous patients, 43·2% relapsed early and 3·4% relapsed late. However, among the allogeneic patients, 13·2% relapsed early and only 1·3% late. The five‐year overall survival from relapse was 5·8% and 20% in the early and late relapse patients respectively. In conclusion, late relapse in adults with ALL is not uncommon, and is associated with better outcome after relapse compared to early relapse.

Successes and challenges in the treatment of pediatric acute myeloid leukemia: a retrospective analysis of the AML-BFM trials from 1987 to 2012

Overall survival (OS) of pediatric patients with acute myeloid leukemia (AML) increased in recent decades. However, it remained unknown whether advances in first-line treatment, supportive care, or second-line therapy mainly contributed to this improvement. Here, we retrospectively analyzed outcome and clinical data of 1940 pediatric AML patients (younger than 18 years of age), enrolled in the population-based AML-BFM trials between 1987 and 2012. While 5-year probability of OS (pOS) increased from 49 ± 3% (1987-1992) to 76 ± 4% (2010-2012; p < 0.0001), probability of event-free survival only improved from 41 ± 3% (1987-1992) to 50 ± 2% (1993-1998; p = 0.02) after introduction of high-dose cytarabine/mitoxantrone, but remained stable since then. Non-response and relapse rates stayed constant despite intensified first-line therapy (p = 0.08 and p = 0.17). Reduced fatal bleedings and leukostasis translated into fewer early deaths (8.1%vs. 2.2%; p = 0.001). Strikingly, pOS after non-response (13 ± 5% (1987-1992) vs. 43 ± 7% (2005-2010); p < 0.0001) or relapse (19 ± 4% vs. 45 ± 4%; p < 0.0001) improved. After 1999, more relapsed or refractory patients underwent hematopoietic stem cell transplantation (HSCT) with increased pOS after HSCT (29 ± 5% (1993-1998) vs. 50 ± 4% (2005-2010); p < 0.0001). Since efficacy of salvage therapy mainly contributed to better outcome in pediatric AML, our analysis indicates that a better allocation of patients, who cannot be cured with conventional chemotherapy, to an early "salvage-like" therapy is necessary.

Salvaged allogeneic hematopoietic stem cell transplantation for pediatric chemotherapy refractory acute leukemia

There is an ongoing debate concerning the performance of salvaged allogeneic hematopoietic stem cell transplantation (allo-HSCT) in pediatric patients with acute refractory leukemia, in whom the prognosis is quite dismal. Few studies have ever been conducted on this subject. This may be partly due to missed opportunities by majority of the patients in such situations. To investigate the feasibility, evaluate the efficiency, and identify the prognostic factors of allo-HSCT in this sub-setting, the authors performed a single institution-based retrospective analysis. A total of 44 patients, of whom 28 had acute myeloid leukemia (AML), 13 had acute lymphocytic leukemia (ALL), and 3 had mixed phenotype leukemia (MPL), were enrolled in this study. With a median follow-up of 19 months, the estimated 2-year overall survival (OS) and progression free survival (PFS) were 34.3% (95% CI, 17.9–51.4%) and 33.6% (95% CI, 18.0–50.1%), respectively. The estimated 2-year incidence rates of relapse and non-relapse mortality (NRM) were 43.8% (95% CI 26.4–60.0%) and 19.6% (95% CI 9.1–32.9%), respectively. The estimated 100-day cumulative incidence of acute graft versus host disease (aGvHD) was 43.6% (95% CI 28.7–57.5%), and the 1-year cumulative incidence of chronic GvHD (cGvHD) was 45.5% (95% CI 30.5–59.3%). Compared with the previous studies, the multivariate analysis in this study additionally identified that female donors and cGvHD were associated with lower relapse and better PFS and OS. Male recipients, age younger than 10 years, a diagnosis of ALL, and the intermediate-adverse cytogenetic risk group were associated with increased relapse. On the contrary, extramedullary disease (EMD) and aGvHD were only linked to worse PFS. These data suggested that although only one-third of the patients would obtain PFS over 2 years, salvaged allo-HSCT is still the most reliable and best therapeutic strategy for refractory pediatric acute leukemia. If probable, choosing a female donor, better management of aGvHD, and induction of cGvHD promotes patient survival.

Management of Relapsed/Refractory Acute Myeloid Leukemia in the Elderly: Current Strategies and Developments

Elderly patients with acute myeloid leukemia (AML) who are refractory to or relapse following frontline treatment constitute a poor-risk group with a poor long-term outcome. Host-related factors and unfavorable disease-related features contribute to early treatment failures following frontline therapy, thus making attainment of remission and long-term survival with salvage therapy particularly challenging for elderly patients. Currently, no optimal salvage strategy exists for responding patients, and allogeneic hematopoietic stem cell transplant is the only curative option in this setting; however, the vast majority of elderly patients are not candidates for this procedure due to poor functional status secondary to age and age-related comorbidities. Furthermore, the lack of effective salvage programs available for elderly patients with recurrent AML underscores the need for therapies that consistently yield durable remissions or durable control of their disease. The purpose of this review was to highlight the currently available strategies, as well as future strategies under development, for treating older patients with recurrent AML.

Outcome of children with acute myeloid leukaemia (AML) experiencing primary induction failure in the AIEOP AML 2002/01 clinical trial

Paediatric patients with acute myeloid leukaemia (AML) who fail induction due to primary resistance to chemotherapy account for a significant proportion of cases and have a particularly dismal prognosis. We report the clinical and biological data, and final outcome of 48 paediatric patients with primary-resistant AML enrolled in the Associazione Italiana di Ematologia e Oncologia Pediatrica AML 2002/01 clinical trial. These patients had a significantly higher white blood cell count at diagnosis compared to other AML patients. Cytogenetic and molecular features did not differ between patients with primary induction failure and patients allocated to the high-risk group. For the whole patient population, the probability of overall survival, event-free survival (EFS) and disease-free survival (DFS) was 21·8% ± 6·2, 20·4% ± 5·9, and 49·5% ± 11·3, respectively. Twenty-eight (58%) patients received haematopoietic stem cell transplantation (HSCT); 3 were autologous and 25 were allogeneic. Patients who underwent HSCT had improved EFS (31·2% vs. 5%, P < 0·0001). Only one of the 20 patients who did not receive HSCT is alive and disease free. The 19 patients in complete remission at time of HSCT showed significantly better DFS than the 9 with active disease (46% vs. 0%, P = 0·02). This study represents one of the largest series with long-term follow up of paediatric AML patients with primary refractory disease. Children who underwent transplantation had an encouraging long-term outcome. Disease recurrence remains the major cause of treatment failure; a better understanding of the disease biology is desirable to develop more effective treatment strategies.

Treatment strategies in patients with AML or high-risk myelodysplastic syndrome relapsed after Allo-SCT

Non-relapse mortality after Allo-SCT has significantly decreased over the last years. Nevertheless, relapse remains a major cause for post SCT mortality in patients with AML and high-risk myelodysplastic syndrome (MDS). In this retrospective single-center analysis, we have analyzed the treatment outcomes of 108 patients with AML or MDS, who relapsed after Allo-SCT. Seventy of these patients (65%) were treated with salvage therapies containing chemotherapy alone, allogeneic cell-based treatment or the combination of both. Thirty-eight patients (35%) received palliative treatment. Median OS after diagnosis of relapse was 130 days. Compared with patients who received chemotherapy alone, response to salvage therapy was significantly improved in patients treated with a combination of chemo- and allogeneic cell-based therapy (CR rate 57% vs 13%, P=0.002). Among risk factors concerning pretreatment characteristics, disease status before first Allo-SCT, and details of transplantation, only the time interval from Allo-SCT to relapse was an independent predictor of response to salvage therapy and OS. These data confirmed that time to relapse after transplantation is an important prognostic factor. Up to now, only patients eligible for treatment regimens containing allogeneic cell-based interventions achieved relevant response rates.

Outcome of children treated for relapsed acute myeloid leukemia in Central America

BACKGROUND

Relapsed childhood acute myeloid leukemia (AML) outcomes have not been documented in resource-limited settings. We examined survival after relapse for children with AML (non-APML) and acute promyelocytic leukemia (APML) in Central America.

PROCEDURE

We retrospectively evaluated outcomes of children with first relapse of AML (non-APML) and APML in Guatemala, Honduras, or El Salvador diagnosed between 1997 and 2011. Predictors of subsequent event-free survival (EFS) and overall survival (OS) were examined.

RESULTS

We identified 140 children with relapsed AML (non-APML), and 24 with relapsed APML. Two-year subsequent EFS and OS (±SE) were 7.0 ± 2.5% and 9.1 ± 2.8%, respectively. Worse outcomes were associated with Hispanic or Indigenous heritage, white blood cell count at diagnosis ≥50 × 10(9) /L, and time to relapse <18 months. For those with relapsed APML, subsequent 2-year EFS and OS were 36.7 ± 10.8% and 43.4 ± 12.1%, although few patients survived beyond 3 years. 15.2% of all patients were managed solely with palliative intent following first relapse.

CONCLUSIONS

Children with relapsed AML in Central America rarely survive, so palliative strategies should be considered following relapse in this population. However, children with late relapse or with APML may have a prolonged period of remission with second treatment, and consideration of re-treatment may be appropriate.

Clinical relevance of molecular aberrations in paediatric acute myeloid leukaemia at first relapse

Outcome for relapsed paediatric acute myeloid leukaemia (AML) remains poor. Strong prognostic factors at first relapse are lacking, which hampers optimization of therapy. We assessed the frequency of molecular aberrations (FLT3, NRAS, KRAS, KIT, WT1 and NPM1 genes) at first relapse in a large set (n = 198) of relapsed non-French-American-British M3, non-Down syndrome AML patients that received similar relapse treatment. We correlated molecular aberrations with clinical and biological factors and studied their prognostic relevance. Hotspot mutations in the analysed genes were detected in 92 out of 198 patients (46·5%). In 72 of these 92 patients (78%), molecular aberrations were mutually exclusive for the currently analysed genes. FLT3-internal tandem repeat (ITD) (18% of total group) mutations were most frequent, followed by NRAS (10·2%), KRAS (8%), WT1 (8%), KIT (8%), NPM1 (5%) and FLT3-tyrosine kinase domain (3%) mutations. Presence of a WT1 aberration was an independent risk factor for second relapse (Hazard Ratio [HR] = 2·74, P = 0·013). In patients who achieved second complete remission (70·2%), WT1 and FLT3-ITD aberrations were independent risk factors for poor overall survival (HR = 2·32, P = 0·038 and HR = 1·89, P = 0·045 respectively). These data show that molecular aberrations at first relapse are of prognostic relevance and potentially useful for risk group stratification of paediatric relapsed AML and for identification of patients eligible for personalized treatment.

How I treat paediatric relapsed acute myeloid leukaemia

The prognosis of paediatric acute myeloid leukaemia (AML) has improved significantly over the recent decades, but still about one-third of patients relapse. These patients have a relatively poor prognosis, with a probability of long-term survival from relapse of about 35%. This can only be achieved with very intensive chemotherapy and, usually, allogeneic stem cell transplantation, leading to very significant toxicity and even treatment-related mortality. Major improvements in the treatment of paediatric relapsed AML thus are required still, and several possibilities are discussed. In case of a suspected relapse, a comprehensive diagnostic work-up has to be undertaken, because significant changes in the biological features of the AML cells may have occurred between initial diagnosis and relapse. This review discusses many practical issues that one encounters in the treatment of children with relapsed AML. It will also be of interest for those involved in translational research in AML.

The prognostic significance of early treatment response in pediatric relapsed acute myeloid leukemia: results of the international study Relapsed AML 2001/01

The prognostic significance of early response to treatment has not been reported in relapsed pediatric acute myeloid leukemia. In order to identify an early and easily applicable prognostic factor allowing subsequent treatment modifications, we assessed leukemic blast counts in the bone marrow by morphology on days 15 and 28 after first reinduction in 338 patients of the international Relapsed-AML2001/01 trial. Both day 15 and day 28 status was classified as good (≤20% leukemic blasts) in 77% of patients. The correlation between day 15 and 28 blast percentages was significant, but not strong (Spearman correlation coefficient = 0.49, P<0.001). Survival probability decreased in a stepwise fashion along with rising blast counts at day 28. Patients with bone marrow blast counts at this time-point of ≤5%, 6-10%, 11-20% and >20% had 4-year probabilities of survival of 52%±3% versus 36%±10% versus 21%±9% versus 14%±4%, respectively, P<0.0001; this trend was not seen for day 15 results. Multivariate analysis showed that early treatment response at day 28 had the strongest prognostic significance, superseding even time to relapse (< or ≥12 months). In conclusion, an early response to treatment, measured on day 28, is a strong and independent prognostic factor potentially useful for treatment stratification in pediatric relapsed acute myeloid leukemia. This study was registered with ISRCTN code: 94206677.

Improved outcome in pediatric relapsed acute myeloid leukemia: results of a randomized trial on liposomal daunorubicin by the International BFM Study Group

PURPOSE

In pediatric relapsed acute myeloid leukemia (AML), optimal reinduction therapy is unknown. Studies suggest that liposomal daunorubicin (DNX; DaunoXome; Galen, Craigavon, United Kingdom) is effective and less cardiotoxic, which is important in this setting. These considerations led to a randomized phase III study by the International Berlin-Frankfurt-Münster Study Group.

PATIENTS AND METHODS

Patients with relapsed or primary refractory non-French-American-British type M3 AML who were younger than 21 years of age were eligible. Patients were randomly assigned to fludarabine, cytarabine, and granulocyte colony-stimulating factor (FLAG) or to FLAG plus DNX in the first reinduction course. The primary end point was status of the bone marrow (BM) sampled shortly before the second course of chemotherapy (the day 28 BM). Data are presented according to intention-to-treat for all 394 randomly assigned patients (median follow-up, 4.0 years).

RESULTS

The complete remission (CR) rate was 64%, and the 4-year probability of survival (pOS) was 38% (SE, 3%). The day 28 BM status (available in 359 patients) was good (≤ 20% leukemic blasts) in 80% of patients randomly assigned to FLAG/DNX and 70% for patients randomly assigned to FLAG (P = .04). Concerning secondary end points, the CR rate was 69% with FLAG/DNX and 59% with FLAG (P = .07), but overall survival was similar. However, core-binding factor (CBF) AML treated with FLAG/DNX resulted in pOS of 82% versus 58% with FLAG (P = .04). Grade 3 to 4 toxicity was essentially similar in both groups.

CONCLUSION

DNX added to FLAG improves early treatment response in pediatric relapsed AML. Overall long-term survival was similar, but CBF-AML showed an improved survival with FLAG/DNX. International collaboration proved feasible and resulted in the best outcome for pediatric relapsed AML reported thus far.

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.

Pediatric acute myeloid leukemia

Pediatric acute myeloid leukemia (AML) is currently associated with survival rates as high as 70%. However, many events still occur, side effects are significant, and late effects occur and can even be life-threatening. Thus, the treatment of pediatric AML still needs further improvement. While most study groups agree on several principles of AML treatment, many unanswered questions and even controversies remain, which will be the topic of this review. Relapsed AML, the most frequent event in children, will also be discussed. The controversies justify future clinical studies. Fortunately, biotechnical developments provide novel treatment targets and targeted drugs, and will enable minimal residual disease-driven tailored therapy. Moreover, a wide range of new drugs is being developed. International collaboration is required to perform randomized, or even single-arm clinical studies, in this setting of subgroup-directed therapy, and fortunately is being accomplished. Therefore, optimism is justified and the treatment of pediatric AML will continue to improve.

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.

Consequent and intensified relapse therapy improved survival in pediatric AML: results of relapse treatment in 379 patients of three consecutive AML-BFM trials

Relapse remains the major cause of treatment failure in pediatric acute myeloid leukemia (AML). We analyzed the clinical characteristics, treatment response to relapse treatment and overall survival (OS) of 379 children with AML relapse treated according to three consecutive frontline protocols of the AML-Berlin/Frankfurt/Muenster study group (AML-BFM-87/-93/-98). Of 313 treated patients with data on remission status, 198 children (63%) achieved a second complete remission (CR2). There were no significant differences in remission rates and OS for the intensive reinduction treatment schedules used. The 5-year OS rate was 23% for the total group and 29% for patients treated with curative intent. OS rates increased with study periods from 18 to 34% (P(log rank)=0.012), whereas the proportion of patients receiving only palliative treatment decreased from 23 to 11% (P(CMH)=0.005). Late relapse, no allogeneic stem cell transplantation (SCT) in CR1, age <10 years and favorable cytogenetics were independent favorable prognostic factors for survival. Achievement of CR2 was the most important prognostic factor (OS 44 vs 3%; P(log rank)<0.0001). Overall, one-third of children with relapsed AML can be cured today. SCT in CR2 is recommended for most patients, although its impact on CR2 is discussed.

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.

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.

Outcome of allogeneic hematopoietic stem cell transplantation for children with acute myelogenous leukemia in second complete remission: single center experience

We reviewed 26 consecutive patients with AML who were transplanted in second CR2 between 1994 and 2005. The most common conditioning regimen was CY and TBI. Median age at transplant was 8.9 yr (range 2.2-18.2). Nine patients received related donor, 16 patients received unrelated donors, and one patient received unrelated cord stem cells. Acute grade III-IV and chronic extensive GVHD occurred in eight (30%) and nine (35%) patients, respectively. Six patients (23%) relapsed, four of them died. Six patients (23%) died from TRM. Estimate of three-yr EFS was 0.53 (95% CI; 0.34-0.72). Including the two relapsed patients who were salvaged by DLI and second transplantation, three-yr OS was 0.61 (95% CI; 0.41-0.78) with a median follow-up of three and a half yr (range 1.5-11.2 yr). When entering remission, children with relapsed AML have a reasonable survival with HSCT, but relapse and TRM remain a concern.

Phase II study of clofarabine in pediatric patients with refractory or relapsed acute myeloid leukemia

PURPOSE

To determine the efficacy and safety of clofarabine in pediatric patients with refractory or relapsed acute myeloid leukemia (AML).

PATIENTS AND METHODS

A phase II, open-label, multicenter study was conducted with single-agent clofarabine in pediatric patients with refractory or relapsed AML. Clofarabine was administered intravenously over 2 hours at the pediatric maximum-tolerated dose (MTD) of 52 mg/m(2) daily for 5 consecutive days. Cycles were repeated every 2 to 6 weeks. Responses determined by an independent response review panel.

RESULTS

The 42 patients treated on the study had a median age of 13 years (range, 2 to 22 years) and had received a median number of two (range, one to five) prior regimens. The response rate was 26% and included one complete response without platelet recovery and 10 partial responses. The median duration of response was 20 weeks (range, 2 to >or= 156 weeks). Six of 28 patients who were refractory to the immediately preceding therapy achieved response. Thirteen patients (31%), including seven responders, proceeded to hematopoietic stem-cell transplantation (HSCT) after treatment with clofarabine and survived between 24 to >or= 160 weeks. Five patients (12%) remain alive post-transplantation at >or= 63, >or= 71, >or= 86, >or= 114, and >or= 130 weeks. The most common grade 3 or greater adverse events without regard to causality were febrile neutropenia, catheter-related infection, epistaxis, hypotension, nausea, and fever. Transient elevation of liver enzymes and hypokalemia occurred frequently. Five patients died within 30 days of clofarabine administration secondary to progressive disease, and another five died as a result of an adverse event.

CONCLUSION

Clofarabine is active in pediatric patients with multiply relapsed or refractory AML. Responses allowed several refractory patients to proceed to HSCT. The toxicity profile was expected in this patient population.

Unrelated donor bone marrow transplantation for children with acute myeloid leukemia beyond first remission or refractory to chemotherapy

PURPOSE

Identify prognostic factors that influence outcome after unrelated donor bone marrow transplantation in children with acute myeloid leukemia (AML).

PATIENTS AND METHODS

Included are 268 patients (age <or= 18 years) with AML in second complete remission (n = 142), relapse (n = 90), or primary induction failure (n = 36) at transplantation. All patients received bone marrow grafts from an unrelated donor and a myeloablative conditioning regimen. Cox regression models were constructed to identify risk factors that influence outcome after transplantation.

RESULTS

In this analysis, the only risk factor that predicted leukemia recurrence and overall and leukemia-free survival was disease status at transplantation. The 5-year probabilities of leukemia-free survival were 45%, 20%, and 12% for patients who underwent transplantation at second complete remission, relapse, and primary induction failure, respectively. As expected, risk of acute but not chronic graft-versus-host disease (GVHD) was lower with T-cell-depleted bone marrow grafts; T-cell-depleted grafts were not associated with higher risks of leukemia recurrence. We observed similar risks of leukemia relapse in patients with and without acute and chronic GVHD.

CONCLUSION

Children who underwent transplantation in remission had a superior outcome compared with children who underwent transplantation during relapse or persistent disease. Nevertheless, 20% of children who underwent transplantation in relapse are long-term survivors, suggesting that unrelated donor bone marrow transplantation is an effective therapy in a significant proportion of children with recurrent or primary refractory AML.

Allogeneic stem cell transplantation for children with acute myeloid leukemia in second complete remission

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective therapy for patients with relapsed acute myeloid leukemia. In this retrospective, multicenter study, we analyzed the outcome of 63 children (median age, 7 y; range, 0.2 to 17) who received unmanipulated allo-HSCT in second complete remission. Either a matched family donor or an unrelated donor was used in 29 (46%) and 34 (54%) patients, respectively. The stem cell source was bone marrow in 53 children (84%), peripheral blood in 7 (11%), and cord blood in 3 patients (5%). Preparative regimen included total body irradiation in 25 patients (40%). The 5-year estimates of overall survival and leukemia-free survival were 53% [95% confidence interval (CI) 39-66] and 49% (95% CI 35-63), respectively, whereas the cumulative incidence of relapse and transplant-related mortality (TRM) were 26% (95% CI 16-41) and 25% (95% CI 15-40), respectively. In multivariate analysis, the use of a matched family donor predicted a better probability of LFS [relative risk (RR) 2.29, P=0.05]. Both chronic graft-versus-host disease occurrence and age at diagnosis greater than 11 years were associated with an increased TRM (RR 8.08, P=0.04 and RR 4.38, P=0.05, respectively). These results indicate that allo-HSCT is a procedure able to rescue a significant proportion of children with acute myeloid leukemia in second complete remission, especially if an human leukocyte antigen-compatible relative is employed as donor. Both leukemia recurrence and TRM contributed to treatment failure. Optimization of donor selection and of strategies for both prophylaxis and treatment of graft-versus-host disease may improve the results of unrelated donor allo-HSCT.

A comparison of the outcomes of children with acute myelogenous leukemia in either first or second complete remission (CR1 vs CR2) following allogeneic hematopoietic stem cell transplantation at a single transplant center

We reviewed 70 consecutive children with AML who received hematopoietic stem cell transplantation (HSCT) in our institution between 1994 and 2005. Forty-seven children were transplanted in CR1 and 23 were transplanted in CR2. BU/CY was the most common pretransplant conditioning regimen for CR1 patients and a TBI-based conditioning regimen was the most common regimen for CR2 patients. Most patients transplanted in CR1 (81%) received related donor HSCT, whereas most of the CR2 patients (74%) received unrelated donor HSCT. Expectedly, there was a significant increase in acute GVHD incidence in CR2 patients (40 vs 25% for grades I-II and 30 vs 10% for grades III-IV; P=0.02) and a significant increase in transplant-related mortality (38 vs 11%; P=0.01). Although the difference between 3-year EFS for CR1 and CR2 was not statistically significant, there was a significantly superior 3-year overall survival for CR1 patients (74 vs 51%; P=0.05). Children with relapsed AML who achieve and maintain remission until HSCT, have a reasonable survival, but the outcome of children receiving HSCT in CR1 remains superior.

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.

Outcomes in childhood AML in the absence of transplantation in first remission--Children's Cancer Group (CCG) studies 2891 and CCG 213

BACKGROUND

The majority of childhood acute myeloid leukemia (AML) patients lack a matched-related bone marrow transplant (BMT) donor in first remission.

PROCEDURE

Disease-free survival (DFS), overall survival (OS), relapse-free survival (RFS), and post-relapse outcome were evaluated for children with de novo AML on CCG 213 and the standard timing (ST) and intensive timing (IT) induction arms of CCG 2891 who were randomized to (intent-to-treat, ITT) or who received (as-treated, AT) only chemotherapy intensification.

RESULTS

Outcomes at 8 years post-induction in ITT analysis of chemotherapy intensification were as follows: 31% DFS, 43% OS on CCG 213; 34% DFS, 51% OS on CCG 2891 ST; 48% DFS, 56% OS on CCG 2891 IT. All toxic deaths during and following Capizzi II chemotherapy intensification on both protocols were in patients >3 years of age (P </= 0.001). Black race was a significant poor prognostic factor for OS (P = 0.008, hazard ratio: 1.74, 95% CI: 1.15-2.61). Overall 48% of patients on both trials relapsed and 19.1% of patients who relapsed on these trials survived. CR1 >12 months portends a much better OS for patients who relapse. Post-relapse treatment included BMT in 47% of patients.

CONCLUSIONS

OS on CCG 2891 was superior to CCG 213 but equivalent between ST and IT arms due to better salvage rates post-relapse in ST patients. Overall survival for childhood AML in the absence of BMT in CR1 is influenced by duration of CR1 and by race.

Early pediatric anthracycline cardiotoxicity: managed by serial heart and bone marrow transplantation

We report a favorable outcome in a child who underwent cardiac transplantation for severe early post-anthracycline-induced cardiomyopathy, 9 months after completion of treatment for acute myeloid leukemia (AML). The child suffered a relapse of AML 2 months after cardiac transplantation and then underwent a successful bone marrow transplant. This case is unique in the literature. We believe it offers an alternative strategy for children with hematologic malignancies, where severe early post-anthracycline cardiotoxicity might preclude bone marrow transplantation.

Improved outcome after relapse in children with acute myeloid leukaemia

In the Nordic Society for Paediatric Haematology and Oncology paediatric study acute myeloid leukaemia (AML) 93, event-free survival was 50% and overall survival was 66%, indicating that many patients were cured following relapse. Factors influencing outcome in children with relapsed AML were investigated. The study included all 146 children in the Nordic countries diagnosed with AML between 1988 and 2003, who relapsed. Data on disease characteristics and relapse treatment were related to outcome. Sixty-six percentage achieved remission with survival after relapse (5 years) 34 +/- 4%. Of 122 patients who received re-induction therapy, 77% entered remission with 40 +/- 5% survival. Remission rates were similar for different re-induction regimens but fludarabine, cytarabine, granulocyte colony-stimulating factor-based therapy had low treatment-related mortality. Prognostic factors for survival were duration of first complete remission (CR1) and stem cell transplantation (SCT) in CR1. In early relapse (<1 year in CR1), survival was 21 +/- 5% compared with 48 +/- 6% in late relapse. For children receiving re-induction therapy, survival in early relapse was 29 +/- 6% and 51 +/- 6% in late. Patients treated in CR1 with SCT, autologous SCT or chemotherapy had a survival of 18 +/- 9, 5 +/- 5 and 41 +/- 5%, respectively. Survival was 62 +/- 6% in 64 children given SCT as part of their relapse therapy. A significant proportion of children with relapsed AML can be cured, even those with early relapse. Children who receive re-induction therapy, enter remission and proceed to SCT can achieve a cure rate of 60%.

Prognostic factors and outcome of recurrence in childhood acute myeloid leukemia

BACKGROUND

Outcome after recurrence of childhood acute myeloid leukemia (AML) is poor. We performed this study to identify prognostic factors for recurrence and for survival after recurrence of AML.

METHODS

The clinical characteristics, biological features, treatment modalities, and outcomes of children with de novo AML who were enrolled on 3 consecutive clinical protocols from 1987 to 2002 at St. Jude Children's Research Hospital were studied. Regression modeling was used to identify prognostic factors for recurrence and for survival after recurrence.

RESULTS

The outcome after recurrence was poor, with a 5-year survival estimate of only 23.3% +/- 5.7%. Multivariable analysis indicated that male sex (P = .005), autologous stem cell transplant before recurrence (P = .097), each additional month from diagnosis to recurrence (P = .041), and stem cell transplant after recurrence (P < .001) were associated with a better survival after recurrence, whereas M5 or M7 morphology (P = .001) were significantly predictive of a lower survival estimate after recurrence.

CONCLUSIONS

Survival after recurrence was poor in children with AML. Novel therapies are urgently needed to prevent or to treat recurring AML.

Discovery and development of clofarabine: a nucleoside analogue for treating cancer

The treatment of acute leukaemias, which are the most common paediatric cancers, has improved considerably in recent decades, with complete response rates approaching approximately 90% in some cases. However, there remains a major need for treatments for patients who do not achieve or maintain complete remission, for whom the prognosis is very poor. In this article, we describe the challenges involved in the discovery and development of clofarabine, a second-generation nucleoside analogue that received accelerated approval from the US FDA at the end of 2004 for the treatment of paediatric patients 1-21 years old with relapsed or refractory acute lymphoblastic leukaemia after at least two prior regimens. It is the first such drug to be approved for paediatric leukaemia in more than a decade, and the first to receive approval for paediatric use before adult use.

Combination of tetrandrine as a potential-reversing agent with daunorubicin, etoposide and cytarabine for the treatment of refractory and relapsed acute myelogenous leukemia

The potential mechanism of the chemotherapy resistance in acute myeloid leukemia (AML) is the multidrug resistance (MDR-1) gene product P-glycoprotein (P-gp), which is often overexpressed in myeloblasts from acute myeloid leukemia. In a multicenter clinical trial, 38 patients with poor risk forms of AML were treated with tetrandrine (TET), a potent inhibitor of the MDR-1 efflux pump, combined with daunorubicin (DNR), etoposide and cytarabine (TET-DEC). Overall, post-chemotherapy marrow hypoplasia was achieved in 36 patients. Sixteen patients (42%) achieved complete remission or restored chronic phase, 9 achieved partial remission (PR) and 13 failed therapy. Toxicities included infection, myelosuppression, stomatitis, mucositis, cerebellar toxicity and reversible cardiotoxicity. There was no significant difference in response for P-gp-positive and -negative patients. P-gp function was assessed in 26 patients by flow cytometric analysis, TET-contained plasma-augmented DNR accumulation relative to pretreatment plasma in K562/A02 cells by a median value of 88+/-101% (range, 11-501%). However, there was no difference in DNR uptake between responding and non-responding patients. Our data showed that TET-DEC was relatively well tolerated in these patients with poor risk AML, and had encouraging antileukemic effects.

Autologous Hematopoietic Stem-Cell Transplantation for Children With Acute Myeloid Leukemia in First or Second Complete Remission: A Prognostic Factor Analysis

Purpose

To determine prognostic factors correlated with outcomes after autologous hematopoietic stem-cell transplantation (HSCT) in children with acute myeloid leukemia (AML).

Patients and Methods

We studied 219 children who received autologous HSCT for AML in first complete remission (CR) and 73 children in second CR and who were reported to the Autologous Blood and Marrow Transplant Registry. Among 29 of 73 patients who underwent transplantation in second CR, duration of first CR was ≥ 12 months.

Results

Three-year cumulative incidences of relapse were 37% (95% CI, 31% to 44%), 60% (95% CI, 41% to 74%), and 36% (95% CI, 20% to 53%) for children in first CR, second CR after a short (< 12 months) first CR, and second CR after a long (≥ 12 months) first CR, respectively. Corresponding 3-year probabilities of leukemia-free survival were 54% (95% CI, 47% to 60%), 23% (95% CI, 10% to 39%), and 60% (95% CI, 42% to 75%). In multivariate analyses, risks of relapse, mortality, and treatment failure (relapse or death, inverse of leukemia-free survival) were higher for patients in second CR after a short first CR than for the other two groups. Transplant-related mortality, treatment failure, and overall mortality rates were higher in older (> 10 years) children.

Conclusion

Duration of first CR seems to be the most important determinant of outcome. Results in children who experience treatment failure with conventional chemotherapy support the use of autologous transplantation as salvage therapy if such patients achieve a subsequent CR.

Outcome in children with relapsed acute myeloid leukemia after initial treatment with the French Leucemie Aique Myeloide Enfant (LAME) 89/91 protocol of the French Society of Pediatric Hematology and Immunology

PURPOSE

After present first-line therapies for childhood acute myeloid leukemia (AML), nearly 40% of patients still relapse. The goals of this retrospective study were to determine whether these children could be treated successfully with a salvage regimen and to establish the optimal therapeutic strategy.

PATIENTS AND METHODS

In the multicentric, prospective, Leucémie Aiquë Myéloïde Enfant 89/91 protocol, 106 of the 308 children enrolled between 1988 and 1998 relapsed. Initial treatment after the first complete remission (CR1) had been allogenic HLA-identical bone marrow transplantation (BMT; n = 21) or chemotherapy (n = 85). Treatment procedures were scheduled according to the choice of each participating institution.

RESULTS

When reinduction therapy was attempted, second complete remission (CR2) was obtained in 71% of patients (68 of 96 patients). BMT was performed in 53 (78%) of these 68 patients (autograft, mainly harvested in CR1, n = 25; matched sibling-donor BMT, n = 12; or alternative-donor BMT, n = 16). The 5-year overall survival (OS) rate for all 106 patients was 33%, and the disease-free survival (DFS) rate for children in CR2 was 45%. Multivariate analysis of re-treated children showed that the 5-year OS was higher if the CR1 had been longer than 12 months compared with less than 12 months (54% v 24%, respectively; P =.001) and lower if maintenance therapy had been given after CR1 compared with chemotherapy without maintenance therapy or HLA-identical BMT (12% v 40% v 52%, respectively; P =.002). For patients attaining CR2, the 5-year DFS rate was not significantly different for matched sibling-donor BMT (60%), autograft (47%), or alternative-donor BMT (44%).

CONCLUSION

After aggressive first-line therapy, one third of unselected, relapsing AML children could be cured. Further prospective trials are warranted to define the optimal reinduction regimen and megadose chemotherapy and to evaluate the late effects of these therapies.

Impact of cytogenetics on the prognosis of adults with de novo AML in first relapse

Karyotype is an important prognostic factor in patients with newly diagnosed acute myeloblastic leukaemia (AML). The prognostic value of cytogenetics on the outcome of patients with AML in relapse has not yet been well defined. We analysed the clinical outcome of 152 patients with de novo, chemotherapy-treated AML in first relapse according to the cytogenetic classification of the United Kingdom Medical Research Council. The rate of second complete remission (CR) (88, 64 and 36%) and the probability of survival at 3 years (43, 18 and 0%) were significantly different between the favourable, intermediate and adverse cytogenetic risk groups, respectively. Compared to the favourable group, the relative risk (RR) of death (multivariate analyses) was 2.6 (confidence interval (CI): 1.5-4.4, P<0.001) for the intermediate and 3.7 (CI: 1.7-7.9, P=0.001) for the adverse group. The prognostic value of the duration of first CR was confirmed (RR of death: 2.0 (CI: 1.0-4.0) for each additional year in first CR), whereas the FLT3 mutation obtained at diagnosis did not markedly influence the outcome of patients with AML in relapse. In conclusion, our results indicate that both karyotype and the duration of first CR are independent prognostic factors for patients with de novo AML in first relapse.

The search for optimal treatment in relapsed and refractory acute myeloid leukemia

Despite the significant progress in the treatment of AML during the last 5-10 years, 20-40% of patients still do not achieve remission with standard induction therapy. In addition, 50-70% of patients in CR are likely to relapse. A major limitation of successful AML therapy is intrinsic or acquired drug resistance. Several pharmacological inhibitors of mechanisms inducing chemoresistance in leukemic cells have been investigated. New cytotoxic drugs, agents with novel mechanisms of action, and new treatment strategies are currently being investigated. The management of refractory or relapsed AML patients is reviewed in this study.

Phase I study of irofulven (MGI 114), an acylfulvene illudin analog, in patients with acute leukemia

Irofulven (MGI 114, 6-hydroxymethylacylfulvene, HMAF) is a semisynthetic illudin analog with broad in vitro anti-neoplastic activity. In this leukemia phase I study, we investigated the toxicity profile and activity of Irofulven in patients with primary refractory or relapsed acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), or myelodysplastic syndromes (MDS). Irofulven was given as an intravenous infusion over five minutes daily for five days. The starting dose was 10 mg/m2/day (50 mg/m2/course). Courses were scheduled to be given every 3-4 weeks according to toxicity and antileukemic efficacy. Twenty patients [AML: 17 patients; MDS: one patient; ALL: one patient; mixed lineage acute leukemia: one patient] were treated. Nausea, vomiting, hepatic dysfunction, weakness, renal dysfunction, and pulmonary edema were dose limiting toxicities, occurring in two of five patients treated at 20 mg/m2/day and two of three patients treated at 12.5 mg/m2/day. The MTD was defined as 10 mg/m2/day for five days. One patient with primary resistant AML achieved complete remission. Proposed phase II studies will further define the activity of Irofulven in patients with better prognosis AML and in other hematological malignancies, both as a single agent and in combination regimens, particularly with topoisomerase 1 inhibitors.

Prognosis of patients with a second relapse of acute myeloid leukemia

Recurrence of the disease is the major problem in the treatment of acute myeloid leukemia (AML). The majority of patients who achieve a second remission will ultimately relapse. In this retrospective single-center study, we have analyzed the outcome of patients with a second relapse and tried to define the prognostic factors in intensively treated patients. Of 534 patients with AML, 62 had a second relapse. Thirty-three received further intensive chemotherapy (CT). Eighteen patients (55%) achieved a third complete remission (CR). The early death (ED) rate was only 9%. The overall survival (OS) of treated vs untreated patients was 6.9 vs 1.3 months, respectively (P = 0.01). The major selection criteria for a third CT were a favourable (t(15;17),t(8;21),inv(16)) or normal karyotype, long (>11 months) second CR (P < or = 0.005) and no previous bone marrow transplantation (BMT)(P < 0.01). Favorable or normal karyotype, second CR >11 months, as well as no previous BMT (P < 0.01) were associated with the achievement of a third CR. Favorable (P < 0.005) or normal karyotype (P < 0.01), as well as a second CR >11 months (P < 0.005) were associated with prolonged survival after CT. The median OS for patients receiving CT with favorable or normal cytogenetics, a second CR > 11 months, but no previous BMT was 26.5 months. Five patients with favorable or normal karyotype achieved a fourth or fifth remission. We conclude that intensive CT is associated with a survival benefit and good quality of life if patients are properly selected.

Therapy for childhood acute myeloid leukemia: role of allogeneic bone marrow transplantation

Acute myeloid leukemia (AML) has one of the lowest survival rates of childhood cancers. The first significant improvement in AML therapy started with the introduction of the now standard regimen of 3 days of anthracyclines and 7 days of cytarabine (Ara-C), the so-called 3+7 combinations. Several different therapeutic approaches have been taken in attempts to improve the outcome, including intensification of therapy both for remission induction and in the postremission phase. Intensification of postremission therapy included multiple courses of high-dose chemotherapy and/or myeloablative therapy followed by stem- cell rescue from either allogeneic or autologous sources. Furthermore, risk-tailored therapy is now possible, by cytogenetic risk stratification, promptness of remission induction, and identification of distinct clinical subgroups such as children with Down syndrome. This approach is rapidly changing potential therapeutic strategies for children with AML. It is in this changing mileu that we address the proper role of stem-cell transplantation, a modality that is changing (like chemotherapy) with expanding stem-cell sources and approaches to decrease transplant-related toxicity.

Mitoxantrone, etoposide, and cyclosporine therapy in pediatric patients with recurrent or refractory acute myeloid leukemia

PURPOSE

To determine the remission rate and toxicity of mitoxantrone, etoposide, and cyclosporine (MEC) therapy, multidrug resistance-1 (MDR1) status, and steady-state cyclosporine (CSA) levels in children with relapsed and/or refractory acute myeloid leukemia.

PATIENTS AND METHODS

MEC therapy consisted of mitoxantrone 6 mg/m(2)/d for 5 days, etoposide 60 mg/m(2)/d for 5 days, and CSA 10 mg/kg for 2 hours followed by 30 mg/kg/d as a continuous infusion for 98 hours. Because of pharmacokinetic interactions, drug doses were decreased to 60% of those found to be effective without coadministration of CSA. MDR1 expression was evaluated by reverse transcriptase polymerase chain reaction, flow cytometry, and the ability of CSA at 2.5 micromol/L to increase intracellular accumulation of (3)H-daunomycin in blasts from bone marrow specimens.

RESULTS

The remission rate was 35% (n = 23 of 66). Overall, 35% of patients (n = 23) achieved complete remission (CR), 12% of patients (n = 8) achieved partial remission, and 9% of patients (n = 6) died of infection. Exposure to CSA levels of greater than 2,400 ng/mL was achieved in 95% of patients (n = 56 of 59). Toxicities included infection, cardiotoxicity, myelosuppression, stomatitis, and reversible increases in serum creatinine and bilirubin. In most who had relapsed while receiving therapy or whose induction therapy had failed, response was not significantly different for MDR1-positive and MDR1-negative patients.

CONCLUSION

Serum levels of CSA capable of reversing multidrug resistance are achievable in children with acceptable toxicity. The CR rate of 35% achieved in this study is comparable to previously reported results using standard doses of mitoxantrone and etoposide. The use of CSA may have improved the response rate for the MDR1-positive patients so that it was not different from that for the MDR1-negative patients.