Outcome for children with relapsed acute myeloid leukaemia following initial therapy in the Medical Research Council (MRC) AML 10 trial. MRC Childhood Leukaemia Working Party

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.

Prognostic significance of chromosomal abnormalities at relapse in children with relapsed acute myeloid leukemia: A retrospective cohort study of the Relapsed AML 2001/01 Study

BACKGROUND

In addition to treatment response, cytogenetic and molecular aberrations are the most important prognostic factors in children with de novo acute myeloid leukemia (AML). However, little is known about cytogenetics at the time of relapse.

METHODS

This international study analyzed the prognostic value of cytogenetic profiles and karyotypic changes in pediatric relapsed AML in relation to the probability of event-free (pEFS) and overall survival (pOS). For this purpose, cytogenetic reports from all patients registered on the Relapsed AML 2001/01 Study were reviewed and classified.

RESULTS

Cytogenetic information at relapse was available for 403 (71%) of 569 registered patients. Frequently detected aberrations at relapse were t(8;21)(q22;q22) (n = 60) and inv(16)(p13.1q22)/t(16;16)(p13.1;q22) (n = 24), both associated with relatively good outcome (4-year pOS 59% and 71%, respectively). Monosomy 7/7q-, t(9;11)(p22;q23), t(10;11)(p12;q23), and complex karyotypes were associated with poor outcomes (4-year pOS 17%, 19%, 22%, and 22%, respectively). Of 261 (65%) patients for whom cytogenetic data were reliable at both diagnosis and relapse, pEFS was inferior for patients with karyotypic instability (n = 128, 49%), but pOS was similar. Unstable karyotypes with both gain and loss of aberrations were associated with inferior outcome. Early treatment response, time to relapse, and cytogenetic profile at time of relapse were the most important prognostic factors, both outweighing karytoypic instability per se.

CONCLUSION

The cytogenetic subgroup at relapse is an independent risk factor for (event-free) survival. Cytogenetic assessment at the time of relapse is of high importance and may contribute to improved risk-adapted treatment for children with relapsed AML.

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.

Allogeneic hematopoietic stem cell transplant in pediatric acute myeloid leukemia: Lessons learnt from a tertiary care center in India

There is paucity of data on outcomes of MSD-HSCT in children with relapsed or high-risk AML from developing countries, which have unique challenges including adverse host factors and resource constraints. We retrospectively reviewed records of children (age ≤ 18 years) who underwent MSD-HSCT for AML at our center from 2009 to 2019 to evaluate clinical outcome and its predictors using Cox proportional hazards model. There were 46 children (36 boys and 10 girls) with mean age 10.7 ± 4.8 years. Indication for HSCT was relapsed AML in CR2 (n = 37), primary refractory (n = 3), or relapsed refractory disease (n = 3); high-risk (n = 1) or secondary (n = 2) AML in CR1. Five-year EFS and OS were 33.3 ± 7.2% and 36.3 ± 7.6%, respectively. On multivariate analysis, CR1 duration less than 12 months, presence of active disease at transplant, and use of bone marrow stem cell graft were associated with poorer EFS and OS. There was one (2.2%) TRM, while disease relapse occurred in 20/40 patients who underwent HSCT in remission. Though the 5-year EFS and OS were inferior to results reported from high-income countries, relapse (and not TRM) was the major cause of treatment failure. A well-sustained CR1, achievement of disease remission, and use of peripheral blood allograft seem imperative to a successful transplant. Targeted therapy along with HSCT may be the option for those with early relapse.

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.

Pediatric acute myeloid leukemia: updates on biology, risk stratification, and therapy

PURPOSE OF REVIEW

Despite advances in therapy over the past decades, overall survival for children with acute myeloid leukemia (AML) has not exceeded 70%. In this review, we highlight recent insights into risk stratification for patients with pediatric AML and discuss data driving current and developing therapeutic approaches.

RECENT FINDINGS

Advances in cytogenetics and molecular profiling, as well as improvements in detection of minimal residual disease after induction therapy, have informed risk stratification, which now relies heavily on these elements. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. However, recent trials focus on limiting treatment-related toxicity through the identification of low-risk subsets who can safely receive fewer cycles of chemotherapy, allocation of hematopoietic stem-cell transplant to only high-risk patients and optimization of infectious and cardioprotective supportive care.

SUMMARY

Further incorporation of genomic and molecular data in pediatric AML will allow for additional refinements in risk stratification to enable the tailoring of treatment intensity. These data will also dictate the incorporation of molecularly targeted therapeutics into frontline treatment in the hope of improving survival while decreasing treatment-related toxicity.

FLAG/FLAG-IDA regimen for children with relapsed/refractory acute leukemia in the era of targeted novel therapies

BACKGROUND

Outcomes of relapsed/refractory childhood acute leukemia remain poor. We analyzed the safety/efficacy of fludarabine, cytarabine, and granulocyte colony stimulating factor, with/without idarubicin (FLAG ± IDA) as salvage therapy compared with recent published results of novel therapies.

METHODS

This retrospective study included children aged 1 to 15 years with relapsed/refractory acute leukemia who received FLAG ± IDA salvage therapy from January 2000 to December 2014. Patients with infant leukemia, mixed lineage leukemia, Philadelphia-positive acute leukemia, or secondary leukemia were excluded.

RESULT

Fifty patients were identified: 25 with acute lymphoblastic leukemia and 25 with acute myeloid leukemia. The median age at initiation of FLAG ± IDA was seven years. Site of relapse was the bone marrow in 29, isolated central nervous system in 11, and combined in 10 patients. FLAG ± IDA was used after first relapse in 68% and after multiple relapses in 32%. Complete remission was achieved in 34 (68%) patients. No variables predictive of complete remission were identified. Grade 3 or greater toxicity was observed in 96% and 6% died from toxicity. Toxicities included hematologic toxicity (96%), infection (52%), and enterocolitis (28%). Twenty-four of 50 (48%) patients achieved a sustained complete remission and survived to bone marrow transplantation. The five-year overall survival was 23.9% ± 6.9%. Patients achieving second complete remission and patients proceeding to bone marrow transplantation following second complete remission demonstrated significantly improved overall survival (p = 0.001).

CONCLUSION

Despite a 68% complete remission rate using FLAG ± IDA, only 48% of patients survived to bone marrow transplantation. The regimen was associated with 96% toxicity and only one in four patients was alive at five years. This underscores the need to find more effective lower toxicity salvage regimens.

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.

Fludarabine, cytarabine, granulocyte colony-stimulating factor and idarubicin for relapsed childhood acute myeloid leukemia

BACKGROUND

The combination of fludarabine (Flu), high-dose cytarabine (Ara-C) and granulocyte colony-stimulating factor (G-CSF; FLAG), with anthracyclines has become standard chemotherapy for refractory acute myeloid leukemia (AML) in European children and adults. To clarify the efficacy and the safety of FLAG-idarubicin (IDA) for children prospectively, we planned a multicenter phase II study (AML-R11) by the Japanese Pediatric Leukemia/Lymphoma Study Group.

METHODS

Patients with AML aged between 2 and 20 years old, who had the first bone marrow (BM) relapse or induction failure, were enrolled. The FLAG-IDA regimen consisted of Flu 30 mg/m² for 5 days, Ara-C 2 g/m² for 5 days, G-CSF (lenograstim) 5 μg/kg for 6 days and IDA 10 mg/m² for 3 days. The primary endpoint was remission rate after therapy.

RESULTS

Due to drug supply issues, the trial was suspended after the inclusion of seven eligible patients. There were six cases of early relapse within 1 year of the first remission. All seven patients completed the therapy and no early death was observed. Hematological toxicity was common, and one patient developed grade 4 non-hematological toxicity of bacterial meningitis. Although only one patient with late relapse achieved complete remission, minimal residual disease was positive on both flow cytometry and Wilms' tumor 1 mRNA. Two patients were alive in remission following hematopoietic stem cell transplantation, whereas the other five patients died of either the disease or treatment-related causes.

CONCLUSION

FLAG-IDA might be tolerable for children with refractory AML although the efficacy should be further investigated.

Combination of clofarabine, cyclophosphamide, and etoposide for relapsed or refractory childhood and adolescent acute myeloid leukemia

Relapsed/refractory acute myeloid leukemia (AML) has an extremely poor prognosis. We describe 17 children and adolescents with relapsed/refractory AML who received clofarabine, cyclophosphamide, and etoposide. Seven patients (41%) responded: 4 with a complete response (CR); 1 with CR with incomplete platelet recovery; and 2 with a partial response. Additionally, 4 developed hypocellular marrow without evidence of leukemia; 5 patients had resistant disease; and 1 suffered early toxic death. After further therapy including transplantation, 4 patients (24%) are alive without evidence of disease at a median of 60 months. This anthracycline-free regimen may be studied for relapsed or refractory AML, but due to the high risk of marrow aplasia reduced doses of clofarabine and cyclophosphamide should be used.

Outcome after intensive reinduction therapy and allogeneic stem cell transplant in paediatric relapsed acute myeloid leukaemia

Given that 30-40% of children with acute myeloid leukaemia (AML) relapse after primary therapy it is important to define prognostic factors and identify optimal therapy. From 1993 to 2012, 543 children from the Nordic countries were treated according to two consecutive protocols: 208 children relapsed. The influence of disease characteristics, first line treatment, relapse therapy and duration of first remission on outcome was analysed. Second complete remission (CR2) was achieved in 146 (70%) patients. Estimated 5-year overall survival (OS_5y ) was 39 ± 4% for the whole group and 43 ± 4% for the 190 patients given re-induction therapy, of whom 76% received regimens that included fludarabine, cytarabine (FLA) ± anthracyclines, 18% received Nordic Society for Paediatric Haematology and Oncology (NOPHO) upfront blocks and 5% received other regimens. Late relapse ≥1 year from diagnosis, no allogeneic stem cell transplantation (SCT) in first remission and core binding factor AML were independent favourable prognostic factors for survival. For the 128 children (124 in CR2) that received SCT as consolidation therapy after relapse, OS_5y was 61 ± 5%. Four of 19 children (21%) survived without receiving SCT as part of relapse therapy. Our data show that intensive re-induction followed by SCT can give cure rates of 40% in children with relapsed AML.

Acute myeloid leukemia in children: Current status and future directions

Acute myeloid leukemia (AML) accounts for 25% of pediatric leukemia and affects approximately 180 patients annually in Japan. The treatment outcome for pediatric AML has improved through advances in chemotherapy, hematopoietic stem cell transplantation (HSCT), supportive care, and optimal risk stratification. Currently, clinical pediatric AML studies are conducted separately according to the AML subtypes: de novo AML, acute promyelocytic leukemia (APL), and myeloid leukemia with Down syndrome (ML-DS). Children with de novo AML are treated mainly with anthracyclines and cytarabine, in some cases with HSCT, and the overall survival (OS) rate now approaches 70%. Children with APL are treated with an all-trans retinoic acid (ATRA)-combined regimen with an 80-90% OS. Children with ML-DS are treated with a less intensive regimen compared with non-DS patients, and the OS is approximately 80%. HSCT in first remission is restricted to children with high-risk de novo AML only. To further improve outcomes, it will be necessary to combine more accurate risk stratification strategies using molecular genetic analysis with assessment of minimum residual disease, and the introduction of new drugs in international collaborative clinical trials.

Collaborative Efforts Driving Progress in Pediatric Acute Myeloid Leukemia

Diagnosis, treatment, response monitoring, and outcome of pediatric acute myeloid leukemia (AML) have made enormous progress during the past decades. Because AML is a rare type of childhood cancer, with an incidence of approximately seven occurrences per 1 million children annually, national and international collaborative efforts have evolved. This overview describes these efforts and includes a summary of the history and contributions of each of the main collaborative pediatric AML groups worldwide. The focus is on translational and clinical research, which includes past, current, and future clinical trials. Separate sections concern acute promyelocytic leukemia, myeloid leukemia of Down syndrome, and relapsed AML. A plethora of novel antileukemic agents that have emerged, including new classes of drugs, are summarized as well. Finally, an important aspect of the treatment of pediatric AML--supportive care--and late effects are discussed. The future is bright, with a wide range of emerging innovative therapies and with more and more international collaboration that ultimately aim to cure all children with AML, with fewer adverse effects and without late effects.

Gemtuzumab ozogamicin in children and adolescents with de novo acute myeloid leukemia improves event-free survival by reducing relapse risk: results from the randomized phase III Children’s Oncology Group trial AAML0531

PURPOSE

To improve survival rates in children with acute myeloid leukemia (AML), we evaluated gemtuzumab-ozogamicin (GO), a humanized immunoconjugate targeted against CD33, as an alternative to further chemotherapy dose escalation. Our primary objective was to determine whether adding GO to standard chemotherapy improved event-free survival (EFS) and overall survival (OS) in children with newly diagnosed AML. Our secondary objectives examined outcomes by risk group and method of intensification.

PATIENTS AND METHODS

Children, adolescents, and young adults ages 0 to 29 years with newly diagnosed AML were enrolled onto Children’s Oncology Group trial AAML0531 and then were randomly assigned to either standard five-course chemotherapy alone or to the same chemotherapy with two doses of GO (3 mg/m2/dose) administered once in induction course 1 and once in intensification course 2 (two of three).

RESULTS

There were 1,022 evaluable patients enrolled. GO significantly improved EFS (3 years: 53.1% v. 46.9%; hazard ratio [HzR], 0.83; 95% CI, 0.70 to 0.99; P.04) but not OS (3 years: 69.4% v. 65.4%; HzR, 0.91; 95% CI, 0.74 to 1.13; P = .39). Although remission was not improved (88% v. 85%; P = .15), posthoc analyses found relapse risk (RR) was significantly reduced among GO recipients overall (3 years: 32.8% v. 41.3%; HzR, 0.73; 95% CI, 0.58 to 0.91; P = .006). Despite an increased postremission toxic mortality (3 years: 6.6% v. 4.1%; HzR, 1.69; 95% CI, 0.93 to 3.08; P = .09), disease-free survival was better among GO recipients (3 years: 60.6% v. 54.7%; HzR, 0.82; 95% CI, 0.67 to 1.02; P = .07).

CONCLUSION

GO added to chemotherapy improved EFS through a reduction in RR for children and adolescents with AML.

Outcome of children with relapsed acute myeloid leukemia following initial therapy under the AML99 protocol

The outcomes of children with relapsed acute myeloid leukemia (AML) are known to be poor, but remain obscure. We retrospectively analyzed 71 patients who had relapsed following first-line treatment under the AML99 protocol. We investigated the time and site of recurrence, response to re-induction therapy, and performance of hematopoietic stem cell transplantation (HSCT) in relapsed cases, and performed a multivariate analysis to identify prognostic factors. The 5-year overall-survival (OS) rate after relapse was 37 %. Of 71 patients, three died without any anti-leukemic therapy and two underwent allogeneic HSCT. The remaining 66 patients received re-induction chemotherapy, and 33 (50 %) achieved second CR (CR2). Twenty-two of 25 (88 %) late relapse patients and 11 of 41 (27 %) early relapse patients achieved CR2 (P < 0.001). Twenty-nine CR2 cases and 35 non-CR2 cases underwent allogeneic HSCT. The 5-year OS rate was significantly higher in patients who underwent HSCT in CR2 than those in non-CR2 (66 vs. 17 %, P < 0.000001). Multivariate analysis indicated that early relapse (P < 0.05) and the positivity of the FMS-like tyrosine kinase 3--internal tandem duplication (P < 0.05) were adverse prognostic factors for survival. In conclusion, the etiology of relapsed pediatric AML needs to be elucidated and effective chemotherapy should be administered to obtain CR2.

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.

Overview of therapy and strategies for optimizing outcomes in de novo pediatric acute myeloid leukemia

Although acute myelogenous leukemia (AML) accounts for <20 % of leukemia in children, it is responsible for over half of all pediatric leukemia deaths. Improvement in event-free survival rates, now over 50 %, are due largely to intensification of chemotherapy, aggressive supportive care, development of risk stratification based on cytogenetic and molecular markers, and improved salvage regimens. Despite this improvement over the past few decades, the survival rates have recently plateaued, and further improvement will need to take into account advances in molecular characterization of AML, development of novel agents, and better understanding of host factors influencing toxicity and response to chemotherapy. This article reviews the epidemiology and biology trends in diagnosis and treatment of pediatric acute myelogenous leukemia.

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.

AAML0523: a report from the Children's Oncology Group on the efficacy of clofarabine in combination with cytarabine in pediatric patients with recurrent acute myeloid leukemia

BACKGROUND

The discovery of new, effective non-anthracycline-based reinduction regimens for children with recurrent acute myeloid leukemia (AML) is critical. In this phase 1/2 study, the tolerability and overall response rate of clofarabine in combination with cytarabine was investigated in children with recurrent/refractory AML.

METHODS

AAML0523 enrolled 49 children with AML in first recurrence or who were refractory to induction therapy. The study consisted of a dose-finding phase (9 patients) and an efficacy phase (40 patients). Two children received clofarabine at a dose of 40 mg/m(2)/day and 47 children at a dose of 52 mg/m(2)/day.

RESULTS

Toxicities typical for intensive chemotherapy regimens were observed at all doses of clofarabine. The recommended pediatric phase 2 dose of clofarabine in combination with cytarabine was 52 mg/m(2)/day for 5 days. Of 48 evaluable patients, the overall response rate (complete remission plus complete remission with partial platelet recovery) was 48%. Four patients met conventional criteria for complete remission with incomplete count recovery. Twenty-one of 23 responders subsequently underwent hematopoietic stem cell transplantation. The overall survival rate at 3 years was 46% for responders compared with 16% for nonresponders (P < .001). Patients found to have no minimal residual disease at the end of the first cycle by flow cytometric analysis had superior overall survival after 1 year (100% vs 38%; P = .01).

CONCLUSIONS

The combination of clofarabine and cytarabine yielded an acceptable response rate without excess toxicity in children with recurrent AML. The nearly 50% survival rate reported in responders is highly encouraging in these high-risk patients and suggests that this combination is an effective bridge to hematopoietic stem cell transplantation.

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.

Relapsed and refractory pediatric acute myeloid leukemia: current and emerging treatments

Survival rates for children with acute myeloid leukemia (AML) exceed 60 % when modern, intensified chemotherapeutic regimens and enhanced supportive care measures are employed. Despite well-recognized improvements in outcomes, primary refractory or relapsed pediatric AML yields significant morbidity and mortality, and improved understanding of this obstinate population along with refined treatment protocols are urgently needed. Although a significant number of patients with refractory or relapsed disease will achieve remission, long-term survival rates remain poor, and efforts to identify therapies which will improve OS are under continuous investigation. The current fundamental goal of such investigation is the achievement of as complete a remission as possible without dose-limiting toxicities, and the progression to hematopoietic stem cell transplantation thereafter. In this review the scope of the problem of relapsed and refractory AML as well as current and emerging chemotherapy options will be discussed.

Outcome of refractory and relapsed acute myeloid leukemia in children treated during 2005-2011 - experience of the Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG)

Aim of the study

Recent studies showed relatively better outcome for children with refractory (refAML) and relapsed acute myeloid leukemia (relAML). Treatment of these patients has not been unified within Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG) so far. The goal of this study is to analyze the results of this therapy performed between 2005–2011.

Material and methods

The outcome data of 16 patients with refAML and 62 with relAML were analyzed retrospectively. Reinduction was usually based on idarubicine, fludarabine and cytarabine with allogenic hematopoietic stem cell transplant (alloHSCT) in 5 refAML and 30 relAML children.

Results

Seventy seven percent relAML patients entered second complete remission (CR2). Five-year OS and disease-free survival (DFS) were estimated at 16% and 30%. The outcome for patients after alloHSCT in CR2 (63%) was better than that of those not transplanted (36%) with 5-year OS of 34% vs. 2-year of 7% and 5-year DFS of 40% vs. 12.5%. Second complete remission achievement and alloHSCT were the most significant predictors of better prognosis (p = 0.000 and p = 0.024). The outcome of refAML children was significantly worse than relAML with first remission (CR1) rate of 33%, OS and DFS of 25% at 3 years and 53% at 2 years, respectively. All survivors of refAML were treated with alloHSCT after CR1.

Conclusions

The uniform reinduction regimen of the documented efficacy and subsequent alloHSCT in remission is needed to improve the outcome for ref/relAML children treated within PPLLSG. The focus should be on the future risk-directed both front and second line AML therapy.

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.

Intrathecal liposomal cytarabine in relapsed or refractory infant and pediatric leukemias: the Children's Hospital of Philadelphia experience and review of the literature

Intrathecal chemotherapy is integral to curing childhood leukemia; however, bioavailability is limited by the blood-brain barrier. Recently FDA-approved, intrathecal liposomal cytarabine (ITlipAC) increases drug concentration over time with fewer invasive procedures. We present a series of 4 children, including 2 infants, with relapsed central nervous system leukemia who went into remission using ITlipAC, with a review of the literature reporting ITlipAC use in children with relapsed leukemia. Drug-attributable side effects were observed more frequently in children with preexisting neurologic conditions and with adult dosing. Combined with other pediatric reports, our experience supports the efficacy of ITlipAC in pediatric and infant leukemic meningitis.

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.

Salvage treatment for children with refractory first or second relapse of acute myeloid leukaemia with gemtuzumab ozogamicin: results of a phase II study

The prognosis of children with relapsed/refractory acute myeloid leukaemia (AML) is poor, and new therapies are needed. Gemtuzumab ozogamicin (GO) is an anti-CD33 antibody linked to the antitumor antibiotic calicheamicin. We conducted an investigator-initiated phase II study with GO to assess its efficacy and safety, administering two dosages of 7.5 mg/m(2) with a 14 d-interval. Thirty children who were refractory to re-induction at first relapse or suffered from second relapse of AML received a total of 64 infusions of GO. The response rate [complete remission (CR) and CR with insufficient platelet recovery] was 37%. Nine patients were subsequently transplanted (median time to transplant, 4 weeks, range 3-21 weeks), and three of these patients are currently in continuous CR with a median follow-up of >3 years, and can considered to be cured. This resulted in a statistically significant survival advantage for children who responded to GO versus those who did not [27% (standard error 13%) vs. 0%, respectively, P = 0.001]. All other children died, mainly from progressive disease. The treatment was generally well tolerated by most patients. The frequency of transient transaminatis was low. All but one patient received defibrotide prophylaxis during the transplant procedure, and no cases of veno-occlusive disease were noted. This study showed a favourable safety/efficacy profile of single-agent GO in children with refractory first or second relapse of AML.

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.

A multi-center phase I study of clofarabine, etoposide and cyclophosphamide in combination in pediatric patients with refractory or relapsed acute leukemia

This Phase I study of clofarabine with etoposide and cyclophosphamide for children with relapsed/refractory acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) was conducted to determine the maximum tolerated dose (MTD), dose-limiting toxicities and the recommended phase 2 doses (RP2Ds). All three drugs were administered for five consecutive days in induction and four consecutive days in consolidation, for a maximum of eight cycles. A total of 25 patients (20 ALL and 5 AML) were enrolled in five cohorts. An MTD was not reached. The RP2Ds of clofarabine, cyclophosphamide and etoposide were 40, 440 and 100 mg/m(2)/day, respectively. Complete remission (CR) was achieved in 10 patients (ALL: nine; AML: one), and CR without platelet recovery in six patients (ALL: two; AML: four) for an overall response rate of 64% (ALL: 55%; AML: 100%). Of the 16 responders, 9 patients proceeded to hematopoietic stem cell transplantation. In conclusion, the combination of clofarabine, etoposide and cyclophosphamide was well tolerated and effective in pediatric patients with relapsed/refractory leukemia. Of note, the phase II portion of the trial was amended after the occurrence of unexpected hepatotoxicity. The ongoing phase II study will evaluate the efficacy and safety of this regimen in ALL patients.

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.

Long-term outcome of cord blood transplantation from unrelated donors as an initial transplantation procedure for children with AML in Japan

To assess the outcome of unrelated umbilical cord blood transplantation (UCBT), 141 children with AML who underwent UCBT (39 in first CR (CR1), 33 in CR2, 4 in CR3 and 65 at more advanced stages (not in CR)) were analyzed in a retrospective multicenter study in Japan. Short-term MTX was used for prophylaxis of acute GVHD in 80 cases (57%). The cumulative incidences of neutrophil recovery, platelet recovery and acute GVHD (grades 2-4) were 78.7, 62.4 and 40.1%, respectively, and the 100-day transplantation-related mortality (TRM) was 10.8%. Multivariate analysis showed that an infused CD34(+) cell dose of 1.35 x 10(5) cells per kg or more was associated with favorable neutrophil and platelet recovery, and that short-term MTX was associated with a lower 100-day TRM. The 6-year relapse rate was 38.8% and was associated with disease status. Six-year overall survival was 45.8% (70.4+/-8.3% in CR1, 59.3+/-11.3% in CR2, 75.5+/-21% in CR3 and 20.6+/-6.2% for children with non-CR). We conclude that the results of UCBT are particularly promising for children with a karyotype suggesting a poor prognosis, and for those who receive transplants in CR2 and CR3 after an early relapse.

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.