Impact of disease risk on efficacy of matched related bone marrow transplantation for pediatric acute myeloid leukemia: the Children's Oncology Group

Hematopoietic Stem Cell Transplantation Outcomes for High-Risk AML: A Report From the Children's Oncology Group

PURPOSE

Hematopoietic stem cell transplantation (HSCT) is used as consolidation for pediatric patients with high-risk AML in first complete remission (CR1). The definition of high-risk AML has evolved considerably over the past two decades with the successive identification of new unfavorable risk factors. We conducted a cross-study analysis to determine whether HSCT improves the outcomes of patients with contemporarily defined high-risk AML.

METHODS

We combined data from AAML0531 and AAML1031, the last two phase III clinical trials completed by the Children's Oncology Group (COG). These two trials established the prognostic importance of measurable residual disease (MRD) and several high-risk cryptic cytogenetic/molecular (CM) alterations, which were applied to reclassify patients in the current COG phase III clinical trial, AAML1831. We compared the outcomes after HSCT in CR1 with those after chemotherapy alone in CR1 in the redefined high-risk group.

RESULTS

Our study cohort comprised 463 patients with high-risk CM alterations and 72 patients with standard-risk (SR) CM results with positive MRD at end of induction I. In all, 33.9% and 45.8% of these groups underwent HSCT in CR1, respectively. HSCT was associated with decreased relapse and improved disease-free survival (DFS) in both groups. In the high-risk CM group, 5-year DFS was 26.0% (95% CI, 20.6 to 31.6) and 49.8% (95% CI, 41.7 to 57.4; P < .001) in patients receiving chemotherapy alone and HSCT, respectively. In the SR CM and MRD+ groups, DFS was 16.9% (95% CI, 4.3 to 36.7) compared with 50.9% (95% CI, 32.7 to 66.5; P = .032). HSCT was also associated with improvement in outcomes based on multivariable analysis and across subgroups defined by clinical trial and by high-risk CM subtype, with the exception of chromosome 7 or 5 loss.

CONCLUSION

HSCT was associated with improved outcomes in pediatric patients with contemporarily defined high-risk AML.

Pediatric AML: state of the Art and Future Directions

Pediatric acute myeloid leukemia (AML) is a heterogeneous and aggressive hematological malignancy. Despite advances in treatment, the survival rates remain unsatisfactory, emphasizing the need for innovative therapeutic approaches. This narrative review presents a comprehensive overview of the current approach and likely future directions for pediatric AML. The distinct genetic, epigenetic, and molecular features of pediatric AML contribute to its complex pathophysiology and impact on prognosis. Current treatment practices involve a multifaceted approach combining chemotherapy, molecularly targeted therapies, and hematopoietic stem cell transplantation. However, intensive treatment often leads to significant acute and long-term toxicity. Emerging strategies, including precision medicine, immunotherapy, and novel agents, hold promise for improving outcomes and minimizing adverse effects. Ongoing clinical trials are investigating the potential of these innovative approaches to transform pediatric AML care. By highlighting the evolving treatment paradigms and future perspectives, this review underscores the importance of continued research and development in pediatric AML to enhance the survival rates and quality of life of these young patients.

Matched unrelated donor transplantation versus haploidentical transplantation with post-transplant cyclophosphamide in children with acute myeloid leukemia: a PDWP-EBMT study

In children with acute myeloid leukemia (AML) who lack a human leukocyte antigen (HLA) identical sibling, the donor can be replaced with an HLA-matched unrelated donor (MUD) or a haploidentical donor (haplo). We compared outcomes of patients <18 years with AML in first and second complete remission (CR1 and CR2) undergoing a hematopoietic stem cell transplantation (HCT) either with a MUD with anti-thymocyte globulin (ATG) (N=420) or a haplo HCT with post-transplant cyclophosphamide (PT-CY) (N=96) after a myeloablative conditioning regimen (MAC) between 2011 and 2021, reported to the European Society for Blood and Marrow Transplantation. A matched pair analysis was performed to adjust for differences among groups. The final analysis was performed on 253 MUD and 95 haplo-HCT. In the matched cohort, median age at HCT was 11.2 and 10 years and median year of HCT was 2017 and 2018, in MUD and haplo-HCT recipients, respectively. The risk of grade III-IV acute graft-versus-host disease (aGVHD) was significantly higher in the haplo group (hazard ratio [HR]=2.33, 95% confidence interval [CI]: 1.18-4.58; P=0.01). No significant differences were found in 2 years overall survival (OS; 78.4% vs. 71.5%; HR=1.39, 95% CI: 0.84-2.31; P=0.19), leukemia-free survival (LFS; 72.7% vs. 69.5%; HR=1.22, 95% CI: 0.76-1.95; P=0.41), CI of relapse (RI; 19.3% vs. 19.5%; HR=1.14, 95% CI: 0.62-2.08; P=0.68) non-relapse-mortality (NRM; 8% vs. 11%; HR=1.39, 95% CI: 0.66-2.93; P=0.39) and graft-versus-host free relapse-free survival (GRFS; 60.7% vs. 54.5%, HR=1.38, 95% CI: 0.95-2.02; P=0.09) after MUD and haplo-HCT respectively. Our study suggests that haplo-HCT with PT-CY is a suitable option to transplant children with AML lacking a matched related donor.

Cytogenetic abnormalities predict survival after allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia: a PDWP/EBMT study

Poor-risk (PR) cytogenetic/molecular abnormalities generally direct pediatric patients with acute myeloid leukemia (AML) to allogeneic hematopoietic stem cell transplant (HSCT). We assessed the predictive value of cytogenetic risk classification at diagnosis with respect to post-HSCT outcomes in pediatric patients. Patients younger than 18 years at the time of their first allogeneic HSCT for AML in CR1 between 2005 and 2022 who were reported to the European Society for Blood and Marrow Transplantation registry were subgrouped into four categories. Of the 845 pediatric patients included in this study, 36% had an 11q23 abnormality, 24% had monosomy 7/del7q or monosomy 5/del5q, 24% had a complex or monosomal karyotype, and 16% had other PR cytogenetic abnormalities. In a multivariable model, 11q23 (hazard ratio [HR] = 0.66, P = 0.03) and other PR cytogenetic abnormalities (HR = 0.55, P = 0.02) were associated with significantly better overall survival when compared with monosomy 7/del7q or monosomy 5/del5q. Patients with other PR cytogenetic abnormalities had a lower risk of disease relapse after HSCT (HR = 0.49, P = 0.01) and, hence, better leukemia-free survival (HR = 0.55, P = 0.01). Therefore, we conclude that PR cytogenetic abnormalities at diagnosis predict overall survival after HSCT for AML in pediatric patients.

Children's Oncology Group's 2023 blueprint for research: Cellular therapy and stem cell transplantation

Since the publication of the last Cellular Therapy and Stem Cell Transplant blueprint in 2013, Children's Oncology Group cellular therapy-based trials advanced the field and created new standards of care across a wide spectrum of pediatric cancer diagnoses. Key findings include that tandem autologous transplant improved survival for patients with neuroblastoma and atypical teratoid/rhabdoid brain tumors, one umbilical cord blood (UCB) donor was safer than two UCB donors, killer immunoglobulin receptor (KIR) mismatched donors did not improve survival for pediatric acute myeloid leukemia when in vivo T-cell depletion is used, and the depth of remission as measured by next-generation sequencing-based minimal residual disease assessment pretransplant was the best predictor of relapse for acute lymphoblastic leukemia. Plans for the next decade include optimizing donor selection for transplants for acute leukemia/myelodysplastic syndrome, using novel engineered cellular therapies to target a wide array of malignancies, and developing better treatments for cellular therapy toxicities such as viral infections and graft-vs-host disease.

Outcomes of haploidentical haematopoietic stem cell transplantation for adolescent and young adults with acute myeloid leukaemia

We aimed to identify the efficacy of haploidentical related donor (HID) haematopoietic stem cell transplantation (HSCT) in adolescent and young adults (AYAs) with acute myeloid leukaemia (AML) in a large cohort. Consecutive AML AYAs (15-39 years old, n = 599) receiving HID HSCT in complete remission (CR) were included. The 3-year cumulative incidence of measurable residual disease occurrence, relapse and non-relapse mortality after HID HSCT was 28.6% (95% CI: 25.0-32.2), 11.6% (95% CI: 9.0-14.2) and 6.7% (95% CI: 4.7-8.7) respectively. The 3-year probability of event-free survival, leukaemia-free survival (LFS) and overall survival (OS) after HID HSCT was 60.7% (95% CI: 56.9-64.8), 81.7% (95% CI: 78.7-84.9) and 85.6% (95% CI: 82.8-88.4) respectively. In multivariable analysis, AML risk category at diagnosis and comorbidity burdens before HID HSCT were independently associated with LFS and OS. Compared to the older adults (≥ 40 years, n = 355) with AML receiving HID HSCT in CR during the same time period, AYAs have a lower incidence of non-relapse mortality and higher probabilities of LFS and OS. Thus, we firstly confirmed the safety and efficacy of HID HSCT in AYAs with AML-CR.

Measurable Residual Disease and Fusion Partner Independently Predict Survival and Relapse Risk in Childhood KMT2A-Rearranged Acute Myeloid Leukemia: A Study by the International Berlin-Frankfurt-Münster Study Group

PURPOSE

A previous study by the International Berlin-Frankfurt-Münster Study Group (I-BFM-SG) on childhood KMT2A-rearranged (KMT2A-r) AML demonstrated the prognostic value of the fusion partner. This I-BFM-SG study investigated the value of flow cytometry-based measurable residual disease (flow-MRD) and evaluated the benefit of allogeneic stem-cell transplantation (allo-SCT) in first complete remission (CR1) in this disease.

METHODS

A total of 1,130 children with KMT2A-r AML, diagnosed between January 2005 and December 2016, were assigned to high-risk (n = 402; 35.6%) or non-high-risk (n = 728; 64.4%) fusion partner-based groups. Flow-MRD levels at both end of induction 1 (EOI1) and 2 (EOI2) were available for 456 patients and were considered negative (<0.1%) or positive (≥0.1%). End points were 5-year event-free survival (EFS), cumulative incidence of relapse (CIR), and overall survival (OS).

RESULTS

The high-risk group had inferior EFS (30.3% high risk v 54.0% non-high risk; P < .0001), CIR (59.7% v 35.2%; P < .0001), and OS (49.2% v 70.5%; P < .0001). EOI2 MRD negativity was associated with superior EFS (n = 413; 47.6% MRD negativity v n = 43; 16.3% MRD positivity; P < .0001) and OS (n = 413; 66.0% v n = 43; 27.9%; P < .0001), and showed a trend toward lower CIR (n = 392; 46.1% v n = 26; 65.4%; P = .016). Similar results were obtained for patients with EOI2 MRD negativity within both risk groups, except that within the non-high-risk group, CIR was comparable with that of patients with EOI2 MRD positivity. Allo-SCT in CR1 only reduced CIR (hazard ratio, 0.5 [95% CI, 0.4 to 0.8]; P = .00096) within the high-risk group but did not improve OS. In multivariable analyses, EOI2 MRD positivity and high-risk group were independently associated with inferior EFS, CIR, and OS.

CONCLUSION

EOI2 flow-MRD is an independent prognostic factor and should be included as risk stratification factor in childhood KMT2A-r AML. Treatment approaches other than allo-SCT in CR1 are needed to improve prognosis.

Allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia in first complete remission: a meta-analysis

Identification of pediatric patients with acute myeloid leukemia (AML) candidates to receive allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1) is still a matter of debate. Currently, transplantation is reserved to patients considered at high risk of relapse based on cytogenetics, molecular biology, and minimal residual disease (MRD) assessment. However, no randomized clinical trial exists in the literature comparing transplantation with other types of consolidation therapy. Here, we provide an up-to-date meta-analysis of studies comparing allo-HSCT in CR1 with chemotherapy alone as a post-remission treatment in high-risk pediatric AML. The literature search strategy identified 10 cohorts from 9 studies performing as-treated analysis. The quantitative synthesis showed improved overall survival (OS) (relative risk, 1.15; 95% confidence interval [CI], 1.06-1.24; P = 0.0006) and disease-free survival (relative risk, 1.31; 95% CI, 1.17-1.47; P = 0.0001) in the allo-HSCT group, with increased relapse rate in the chemotherapy group (relative risk, 1.26; 95% CI, 1.07-1.49; P = 0.006). Sensitivity analysis including prospective studies alone and excluding studies that reported the comparison only on intermediate-risk patients confirmed the benefit of allo-HSCT on OS. Further research should focus on individualizing allo-HSCT indications based on molecular stratification and MRD monitoring.

Comparison of Pulmonary Toxicity after Total Body Irradiation- and Busulfan-Based Myeloablative Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Patients

Pulmonary toxicity after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for childhood leukemia and myelodysplastic syndrome (MDS), along with the impact of different myeloablative conditioning regimens, remain incompletely described. Here we compared the acute and long-term incidence of pulmonary toxicity (PT) after total body irradiation (TBI)- and busulfan-based myeloablative conditioning. We conducted this retrospective cohort study of 311 consecutive pediatric patients with leukemia or MDS who underwent allo-HSCT at Dana-Farber Cancer Institute/Boston Children's Hospital between 2008 and 2018. PT was graded using Common Terminology Criteria for Adverse Events version 5.0. The primary objective was to compare the cumulative incidence of grade ≥3 and grade 5 PT after TBI-based and busulfan-based myeloablative conditioning using Gray's test. Secondary objectives were to determine factors associated with PT and overall survival (OS) using competing risk analysis and Cox regression analyses, respectively. There was no significant difference between the TBI-conditioned group (n = 227) and the busulfan-conditioned group (n = 84) in the incidence of grade ≥3 PT (29.2% versus 34.7% at 2 years; P = .26) or grade 5 pulmonary toxicity (6.2% versus 6.1% at 2 years; P = .47). Age (hazard ratio [HR], 1.70, 95% confidence interval [CI], 1.11 to 2.59; P = .01), grade ≥2 PT prior to allo-HSCT or preexisting pulmonary conditions (HR, 1.84, 95% CI, 1.24 to 2.72; P < .01), acute graft-versus-host disease (GVHD) (HR, 2.50; 95% CI, 1.51 to 4.14; P < .01), and chronic GVHD (HR, 2.61; 95% CI, 1.26 to 5.42; P = .01) were associated with grade ≥3 PT on multivariable analysis. Grade ≥3 PT was associated with worse OS (81.1% versus 61.5% at 2 years; P < .01). In pediatric allo-HSCT recipients, rates of PT were similar in recipients of TBI-based and recipients of busulfan-based myeloablative conditioning regimens. Age, the presence of PT or preexisting pulmonary conditions prior to transplantation, and the development of either acute or chronic GVHD were associated with grade ≥3 PT post-transplantation. Furthermore, the occurrence of grade 3-4 PT post-transplantation was associated with inferior OS.

Improved outcome in children compared to adolescents and young adults after allogeneic hematopoietic stem cell transplant for acute myeloid leukemia: a retrospective study from the Francophone Society of Bone Marrow Transplantation and Cell Therapy (SFGM-TC)

BACKGROUND

There are currently few data on the outcome of acute myeloid leukemia (AML) in adolescents after allogeneic HSCT. The aim of this study is to describe the outcome and its specific risk factors for children, adolescents and young adults after a first allogeneic HSCT for AML.

METHODS

In this retrospective study, we compared the outcome of AML patients receiving a first allogeneic HSCT between 2005 and 2017 according to their age at transplantation's time: children (< 15 years, n = 564), adolescent and post-adolescent (APA) patients (15-25 years, n = 647) and young adults (26-40 years; n = 1434).

RESULTS

With a median follow-up of 4.37 years (min-max 0.18-14.73 years), the probability of 2-year overall survival (OS) was 71.4% in children, 61.1% in APA patients and 62.9% in young adults (p = 0.0009 for intergroup difference). Both relapse and non-relapse mortality (NRM) Cumulative Incidence (CI) estimated at 2 years were different between the age groups (30.8% for children, 35.2% for APA patients and 29.4% for young adults-p = 0.0254, and 7.0% for children, 10.6% for APA patients and 14.2% for young adults, p < 0.0001; respectively). Whilst there was no difference between the three groups for grade I to IV acute GVHD CI at 3 months, the chronic GVHD CI at 2 years was higher in APA patients and young adults (31.4% and 36.4%, respectively) in comparison to the children (17.5%) (p < 0.0001). In multivariable analysis, factors associated with death were AML cytogenetics (HR1.73 [1.29-2.32] for intermediate risk 1, HR 1.50 [1.13-2.01] for intermediate risk 2, HR 2.22 [1.70-2.89] for high cytogenetics risk compared to low risk), use of TBI ≥ 8 Grays (HR 1.33 [1.09-1.61]), disease status at transplant (HR 1.40 [1.10-1.78] for second Complete Remission (CR), HR 2.26 [1.02-4.98] for third CR and HR 3.07 [2.44-3.85] for active disease, compared to first CR), graft source (HR 1.26 [1.05-1.50] for Peripheral Blood Stem Cells compared to Bone Marrow) and donor age (HR 1.01 (1-1.02] by increase of 1 year).

CONCLUSION

Age is an independent risk factor for NRM and extensive chronic GVHD. This study suggests that APA patients with AML could be beneficially treated with a chemotherapy-based MAC regimen and bone marrow as a stem cells source.

Development and validation of a prognostic scoring model to risk stratify childhood acute myeloid leukaemia

To create a personal prognostic model and modify the risk stratification of paediatric acute myeloid leukaemia, we downloaded the clinical data of 597 patients from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) database as a training set and included 189 patients from our centre as a validation set. In the training set, age at diagnosis, -7/del(7q) or -5/del(5q), core binding factor fusion genes, FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD)/nucleophosmin 1 (NPM1) status, Wilms tumour 1 (WT1) mutation, biallelic CCAAT enhancer binding protein alpha (CEBPA) mutation were strongly correlated with overall survival and included to construct the model. The prognostic model demonstrated excellent discriminative ability with the Harrell's concordance index of 0.68, 3- and 5-year area under the receiver operating characteristic curve of 0.71 and 0.72 respectively. The model was validated in the validation set and outperformed existing prognostic systems. Additionally, patients were stratified into three risk groups (low, intermediate and high risk) with significantly distinct prognosis, and the model successfully identified candidates for haematopoietic stem cell transplantation. The newly developed prognostic model showed robust ability and utility in survival prediction and risk stratification, which could be helpful in modifying treatment selection in clinical routine.

The Role of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) offers potentially curative treatment for many children with high-risk or relapsed acute leukemia (AL), thanks to the combination of intense preparative radio/chemotherapy and the graft-versus-leukemia (GvL) effect. Over the years, progress in high-resolution donor typing, choice of conditioning regimen, graft-versus-host disease (GvHD) prophylaxis and supportive care measures have continuously improved overall transplant outcome, and recent successes using alternative donors have extended the potential application of allotransplantation to most patients. In addition, the importance of minimal residual disease (MRD) before and after transplantation is being increasingly clarified and MRD-directed interventions may be employed to further ameliorate leukemia-free survival after allogeneic HSCT. These advances have occurred in parallel with continuous refinements in chemotherapy protocols and the development of targeted therapies, which may redefine the indications for HSCT in the coming years. This review discusses the role of HSCT in childhood AL by analysing transplant indications in both acute lymphoblastic and acute myeloid leukemia, together with current and most promising strategies to further improve transplant outcome, including optimization of conditioning regimen and MRD-directed interventions.

[Unrelated cord blood stem cell transplantation for high-risk/refractory childhood acute myeloid leukemia: a clinical analysis of 160 cases]

Objective: To retrospectively analyze the clinical outcomes of single unrelated cord blood transplantation (UCBT) in children with high risk and refractory acute myeloid leukemia (AML) . Methods: Between June 2008 and December 2018, a total of 160 consecutive pediatric patients with AML received single UCBT (excluding acute promyelocytic leukemia) . Myeloablative conditioning (MAC) regimen were applied. All patients received a combination of cyclosporine A (CsA) and mycophenolate mofetil (MMF) for the prophylaxis of graft -versus- host disease (GVHD) . Results: The cumulative incidence of neutrophil cells engraftment at day +42 and platelet recovery at day +120 was 95.0% (95% CI 90.0%-97.5%) at a median of 16 days after transplantation (range, 11-38 days) and 85.5% (95%CI 83.3%-93.4%) with a median time to recovery of 35 days (range, 13-158) , respectively. Incidence of grades Ⅱ-Ⅳ and Ⅲ-Ⅳ acute GVHD and chronic GVHD were 37.3% (95%CI 29.3%-45.2%) , 27.3% (95%CI 20.0%-35.0%) and 22.4% (95%CI 15.5%-28.7%) , respectively. The transplant-related mortality (TRM) at 360 day was 13.1% (95%CI 8.4%-18.9%) . The 5-year cumulative incidence of relapse was 13.8% (95%CI 8.5%-20.3%) . The 5-year disease-free survival (DFS) and overall survival (OS) were 71.7% (95%CI 62.7%-77.8%) and 72.2% (95%CI 64.1%-78.7%) , respectively. The 5-year GVHD and relapse free survival (GRFS) was 56.1% (95%CI 46.1%-64.9%) . The 5-year cumulative recurrence rates of CR1, CR2, and NR groups were 5.3%, 19.9%, and 30.9% (P=0.001) , and the 5-year OS rates were 79.9% (95%CI 70.3%-86.7%) , 71.1% (95%CI 50.4%-84.4%) and 52.9% (95%CI 33.0%-69.3%) (χ(2)=7.552, P=0.020) , respectively. Conclusions: For pediatric patients with high risk and refractory AML, UCBT is a safe and effective treatment option, and it is favorable to improve the survival rate in CR1 stage.

Treatment of acute myeloid leukemia in children: A practical perspective

Pediatric acute myeloid leukemia (AML) is a heterogeneous disease that requires a multifaceted treatment approach. Although outcomes for low-risk AML have improved significantly over recent decades, high-risk AML continues to be associated with an adverse prognosis. Recent advances in molecular diagnostics, risk stratification, and supportive care have contributed to improvements in outcomes in pediatric AML. Targeted approaches, for example, the use of tyrosine kinase inhibitors to treat FLT3-ITD AML, offer promise and are currently undergoing clinical investigation in pediatric patients. New approaches to hematopoietic stem cell transplantation, including the use of haploidentical donors, are significantly expanding donor options for patients with high-risk AML. This review provides an overview of recent advances in the treatment of pediatric AML that are likely to have clinical impact and reshape the standard of care.

Acute lymphoblastic leukemia

The survival of patients with acute lymphoblastic leukemia (ALL) has improved significantly with the use of intensive multimodality treatment regimens including chemotherapy, high-dose chemotherapy and stem cell rescue, and radiation therapy when indicated. This report summarizes the treatment strategies, especially radiation therapy in the Children's Oncology Group for children with ALL. Currently, radiation therapy is only indicated for children with high-risk CNS involvement at diagnosis or relapse, testicular relapse and as part of the conditioning regimen for hematopoietic stem cell transplantation. Future research strategies regarding the indications for and dosages of radiation therapy and novel radiation techniques are discussed.

Attempts to optimize postinduction treatment in childhood acute myeloid leukemia without core-binding factors: A report from the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG)

We previously reported that risk-stratified therapy and intensive postremission chemotherapy (PRC) contributed to the improved survival of childhood acute myeloid leukemia (AML) in the AML99 study, which led us to consider a reduction in the number of PRC courses with more restrictive indications for stem cell transplantation (SCT) in the successor AML-05 study. We here report the outcome of AML patients without core-binding factor mutation (non-CBF AML) in the AML-05 study. Two-hundred eighty-nine children (age < 18 years old) with non-CBF AML were eligible. Patients with unfavorable cytogenetics and/or poor bone marrow response to the first induction course were candidates for SCT in the AML-05 study. After two courses of induction, a further three courses of PRC were given in AML-05, while four courses were given in the AML99 study. The 3-year event-free survival (EFS) rate in the AML-05 study (46.7%, 95% CI: 40.6-52.6%) was comparable to that of non-CBF AML in the AML99 study (51.5%, 95% CI: 42.7-59.6%) (P = .16). However, the 3-year overall survival (OS) rate in the AML-05 study (62.9%, 95% CI: 56.3-68.8%) was slightly lower than that in the AML99 study (71.6%, 95% CI: 63.2-78.5%) (P = .060), mainly due to decreased remission induction rate and increased nonrelapsed mortality. In conclusion, reductions in the number of PRC courses from four to three, together with repetitive cycles of high-dose cytarabine, were acceptable for non-CBF childhood AML.

Efficacy of Haploidentical Hematopoietic Stem Cell Transplantation Compared With Chemotherapy as Postremission Treatment of Children With Intermediate-risk Acute Myeloid Leukemia in First Complete Remission

BACKGROUND

The role of haploidentical hematopoietic stem cell transplantation (haplo-HSCT) for children with intermediate-risk acute myeloid leukemia (IR-AML) in first complete remission has been controversial. The present study compared the effect of chemotherapy with unmanipulated haplo-HSCT as treatment of patients with IR-AML in first complete remission (CR1).

PATIENTS AND METHODS

We retrospectively analyzed the outcomes of 80 children with IR-AML and compared the effects of chemotherapy (n = 47) with those of haplo-HSCT (n = 33) as treatment in CR1.

RESULTS

The 3-year overall survival, event-free survival (EFS), and cumulative incidence of relapse (CIR) was 85.4% ± 4.1%, 73.2% ± 5.0%, and 25.4% ± 4.5%, respectively. Compared with the chemotherapy group, the patients in the haplo-HSCT group had a lower CIR (P = .059) and better EFS (P = .108), but roughly equivalent overall survival (P = .841). Multivariate analysis revealed chemotherapy and minimal residual disease (MRD) of ≥ 10^-3 after induction therapy as independent risk factors affecting CIR and EFS. EFS (P = .045) and CIR (P = .045) differed significantly between the 2 treatment groups in patients with MRD of ≥ 10^-3 after induction therapy.

CONCLUSION

Haplo-HSCT might be a feasible option for children with IR-AML in CR1, especially for patients with MRD of ≥ 10^-3 after induction therapy.

Treatments for children and adolescents with AML

In recent decades, survival rates for childhood acute myeloid leukemia have remarkably improved, owing to chemotherapy intensification, allogeneic hematopoietic stem cell transplantation, and improved supportive care. Furthermore, treatment protocols have evolved and are currently better matched to prognostic factors and treatment responses. Recently, new molecular prognostic factors were discovered via leukemia genomic studies. Moreover, new tumor subtypes with independent gene expression profiles have been characterized. To broaden the therapeutic options for patients with poor prognoses, therapies that target specific candidate mutations are being identified. Additionally, new drugs are undergoing clinical trials, and immunotherapy is attracting significant interest as a treatment option for recurrent or refractory childhood acute myeloid leukemia.

Treatment of Childhood Acute Myeloid Leukemia in Uruguay: Results of 2 Consecutive Protocols Over 20 Years

We evaluated the outcome of 71 children with de novo acute myeloid leukemia enrolled in 2 consecutive protocols in the main pediatric hospital in Uruguay. In the LAM97 protocol (n=34), patients received, as consolidation, autologous or allogeneic hematopoietic stem cell transplantation (HSCT), depending on the availability or not of a matched sibling donor. In the LAM08 protocol (n=37), patients were stratified into risk groups, autologous HSCT was abandoned, and allogeneic HSCT was limited to intermediate-risk patients with matched sibling donor and to all patients who fulfilled the high-risk criteria. Complete remission was achieved in 91% and 92% of patients in LAM97 and LAM08, respectively. Deaths in complete remission were 9.6% and 17.6%, respectively. The incidence of relapse was significantly higher in LAM97, 35.4%, versus 12.5% in LAM08. The 5-year event-free survival and overall survival were 50.0% and 55.9% in LAM97 and 59.9% and 64.8% in LAM08. The 5-year overall survival rates in each of the risk groups were 85.7% and 100% for low risk, 50.0% and 61.2% for intermediate risk, and 42.9% and 50.0% for high risk in LAM97 and LAM08 protocols, respectively. Survival has improved over the last 2 decades, and results are comparable to those published in Europe and North America.

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.

Retrospective analysis of children with high-risk acute myeloid leukemia who underwent allogeneic hematopoietic stem cell transplantation following complete remission with initial induction chemotherapy in the AML-05 clinical trial

In the AML-05 clinical trial conducted by the Japanese Pediatric Leukemia/Lymphoma Group from 2006 to 2010, children with high-risk acute myeloid leukemia (HR AML) received allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1). The aim of this study was to investigate the impact of allo-HSCT on the outcome of HR AML. Patients with either monosomy 7, 5q-, t(16;21), Ph1, FLT3-ITD, or induction failure after the first course of chemotherapy were eligible for transplant. Of 53 children with HR AML, 51 received allo-HSCT-45 in CR1, five in CR2, and one with non-CR. t(8;21), t(9;11), and t(16;21) abnormalities were identified in eight, five, and four patients, respectively. The stem cell sources varied-bone marrow in 30 patients, peripheral blood in three, and cord blood in 18. The median follow-up was 62 months. The overall survival (OS) rates at 3 years were 73% and 25% for patients who received transplant at CR1 and ≥CR2, respectively. Multivariable analysis showed that patients with chronic graft-versus-host disease (cGVHD) had better OS. This study supports that allo-HSCT is a suitable treatment for HR AML in CR1. The favorable outcome associated with cGVHD indicates that a graft-versus-leukemia effect might be occurring.

Low-dose azacitidine for relapse prevention after allogeneic hematopoietic cell transplantation in children with myeloid malignancies

BACKGROUND

The prognosis of children who relapse after allogeneic hematopoietic cell transplant (alloHCT) for myeloid malignancies remains poor.

PROCEDURE

To describe the safety and feasibility of post-transplant azacitidine for relapse prevention, we retrospectively reviewed the charts of 18 children undergoing alloHCT for myeloid malignancies.

RESULTS

There were 15 evaluable patients since three patients did not receive planned azacitidine due to early relapse or TRM. Azacitidine (32 mg/m² /dose for 5 days, in 28-day cycles as tolerated up to 1 year post-transplant) was started at a median of 66 days post-transplant (range 42-118). Two-thirds (10/15) of patients received eight or more cycles. Five patients stopped therapy early, only one attributable to toxicity. Mild myelosuppression was the most common reason for cycle delays. Dose modifications were made in three patients. There were three relapses, two of which occurred in patients in CR2 and one in CR1, with a median follow-up of 20 months (range 12.5-28), and no TRM in patients who received azacitidine.

CONCLUSIONS

Post-transplant azacitidine in children is safe and feasible, with most patients successfully receiving all planned cycles. Despite the limitations of a small cohort, low relapse incidence suggests a potential benefit in disease control that warrants further investigation.

Unrelated donor hematopoietic stem cell transplantation for pediatric de novo acute myeloid leukemia with intermediate- or high-risk cytogenetics

The role of unrelated donor HSCT for children with de novo AML in CR1 is controversial. We performed this study to investigate the feasibility of unrelated donor HSCT who initially had intermediate- or high-risk cytogenetics. We retrospectively reviewed medical records of patients with AML who received unrelated HSCT in CR1 at Samsung Medical Center between November 2001 and January 2012. Patients were allocated based on karyotype at diagnosis as follows: (a) low-risk: inv(16), t(16;16), t(8;21), and t(15;17); (b) high-risk: -5, 5q-, -7, 3q abnormalities, t(8;16), t(6;9), t(6;11), t(6;21), t(10;11), complex karyotype (≥3 abnormalities), and acute megakaryocytic leukemia without t(1;22); and (c) IR: all the other karyotypes including normal. Patients in intermediate- or high-risk group who were transplanted with either unrelated CB or matched unrelated BM/mobilized PB in their CR1 were included in this study. The projected OS and EFS rates were 74.9% and 71.1%, respectively, with a median follow-up of 87.3 months after transplantation. The EFS was 70.1%, 80.7%, and 73.9% for CB, BM, and mobilized PB groups, respectively (P = 0.89), and 73.9% and 70.6% for IR and high-risk groups (P = 0.76). The leading cause of death was relapse (n = 8), and only one patient died from non-relapse cause. Unrelated donor HSCT seems a feasible approach for children with intermediate- or high-risk AML in CR1. Relapse remains the leading cause of treatment failure among these patients.

Response-guided chemotherapy for pediatric acute myeloid leukemia without hematopoietic stem cell transplantation in first complete remission: Results from protocol DB AML-01

BACKGROUND

Children with acute myeloid leukemia (AML) have a 70% survival rate with treatment regimens containing high doses of cytarabine and anthracyclines and, in some, hematopoietic stem cell transplantation (allo-HSCT).

PROCEDURE

In this multicenter Dutch-Belgian protocol (DB AML-01), 112 children with de novo AML were included. Treatment was stratified according to day 15 bone marrow response after the first induction course. Poor responders received a second course without delay while good responders awaited hematological recovery. Patients achieving CR after two induction courses continued with three consolidation courses without HSCT in CR1.

RESULTS

The overall remission rate was 93.5%. After a median follow-up of 4.1 years, three-year event-free survival (EFS) was 52.6% (95% CI, 42.9%-61.3%), three-year cumulative incidence of relapse 39.7% (95% CI, 30.1%-49.0%), and three-year overall survival (OS) 74.0% (95% CI, 64.8%-81.2%). Significantly more events occurred in patients with high WBC at diagnosis or FLT3-ITD/NPM1-WT, whereas core binding factor (CBF) leukemia had a significantly better EFS. KMT2A rearrangements and age > 10 years negatively impacted OS.

CONCLUSIONS

DB AML-01 response-guided therapy results in a favorable OS, particularly for children with CBF leukemia, children younger than 10 years or with initial WBC counts below 100 × 10⁹ /L. Outcome of patients with FLT3-ITD/NPM1-WT remains poor and warrants alternative treatment strategies.

Comparison of conditioning regimens for autologous stem cell transplantation in children with acute myeloid leukemia: A nationwide retrospective study in Japan

BACKGROUND

Indications for hematopoietic stem cell transplantation (HSCT) have decreased with the improvement in chemotherapy for pediatric acute myeloid leukemia (AML) in the last decade. We conducted reevaluation of autologous HSCT (AHSCT) to compare myeloablative conditioning (MAC) regimens for pediatric AML without the need for consideration of toxicities caused by allogeneic immune reactions.

PROCEDURE

This retrospective study analyzed the clinical outcomes of 220 children with AML who underwent consecutive AHSCT between 1989 and 2002 in Japan by the national prospective registry. The transplantation outcomes of various conditioning regimens were compared.

RESULTS

The median follow-up period of the survivors was 160 months. The clinical outcomes of busulfan + cyclophosphamide ± etoposide or busulfan + melphalan regimens were significantly superior compared with other busulfan-based and total body irradiation-based regimens (leukemia-free survival [LFS]: 68% vs 42% and 55%, P = 0.001; overall survival [OS]: 74% vs 49% and 61%, P < 0.001). Multivariate analysis showed that busulfan + cyclophosphamide ± etoposide and busulfan + melphalan regimens were independent favorable factors for LFS (hazard ratio: 0.46; P < 0.001) and OS (hazard ratio: 0.40; P < 0.001) compared with the other busulfan-based regimen, and both age 2 years or older and advanced stage at AHSCT were independent poor predictors for LFS and OS, simultaneously.

CONCLUSION

Busulfan + cyclophosphamide ± etoposide and busulfan + melphalan regimens exhibited superior antileukemic effects compared with other BU-based myeloablative regimens.

Allogeneic hematopoietic stem cell transplantation for children and adolescents with high-risk cytogenetic AML: distinctly poor outcomes of FUS-ERG-positive cases

Allocating patients with acute myeloid leukemia and high-risk cytogenetic abnormalities (HR-AML) for allogeneic hematopoietic stem cell transplantation (allo-HSCT) is part of the standard treatment protocol; however, whether allo-HSCT truly improves the outcomes in these patients is debatable. Data on 169 children and adolescents with HR-AML who received their first allo-HSCT in first or second remission between 2000 and 2015 were extracted from a nationwide, Japanese HSCT registry. The 3-year disease-free survival (DFS) and overall survival (OS) rates were 55.2% (95% CI, 46.8-62.9%) and 69.6% (61.4-76.3%), respectively, for all the HR-AML patients. In univariate analysis, the cytogenetic subgroup had a significant impact on both the DFS (P = 0.011) and OS (P < 0.001) rates. In particular, 14 patients with t(16;21) showed an extremely poor outcome. Additionally, older age at allo-HSCT (10-19 years old, P = 0.025), myeloablative conditioning with total-body irradiation (P = 0.019), and grade II-IV acute graft-versus-host disease (GVHD, P = 0.049) were associated with inferior OS. The donor type and occurrence of chronic GVHD did not affect the outcome. Multivariate analysis revealed t(16;21) to be associated with increased overall mortality (hazard ratio = 4.416, P < 0.001). Because the outcome of patients with certain HR-AML subgroups, such as t(16;21)-positive cases, is extremely poor even with allo-HSCT in remission, a novel therapy is urgently required.

MLL-rearranged acute myeloid leukemia: Influence of the genetic partner in allo-HSCT response and prognostic factor of MLL 3' region mRNA expression

OBJECTIVE

MLL gene is involved in more than 80 known genetic fusions in acute leukemia. To study the relevance of MLL partner gene and selected gene's expression, in this work, we have studied a cohort of 20 MLL-rearranged acute myeloid leukemia (AML).

METHODS

Twenty MLL-rearranged AML patients along with a control cohort of 138 AML patients are included in this work. By RT-PCR and sequencing, MLL genetic fusion was characterized, and relative gene expression quantification was carried out for EVI1, MEIS1, MLL-3', RUNX1, SETBP1, HOXA5, and FLT3 genes. Risk stratification and association of MLL genetic partner and gene expression to overall survival, in the context of received therapy, were performed.

RESULTS

MLLr cohort showed to have an OS more similar to intermediate-risk AML. Type of MLL genetic partner showed to be relevant in allo-HSCT response; having MLLT1 and MLLT3, a better benefit from it. Expression of MLL-3' region, EVI1 and FLT3, showed association with OS in patients undergoing allo-HSCT.

CONCLUSION

We show that the MLL genetic partner could have implications in allo-HSCT response, and we propose three genes whose expression could be useful for the prognosis of this leukemia in patients undergoing allo-HSCT: 3' region of MLL, EVI1, and FLT3.

Cell therapies for hematological malignancies: don't forget non-gene-modified t cells!

Cell therapy currently performs an important role in the treatment of patients with various hematological malignancies. The response to the cell therapy is regulated by multiple factors including the patient's immune system status, genetic profile, stage at diagnosis, age, and underlying disease. Cell therapy that does not require genetic manipulation can be mediated by donor lymphocyte infusion strategies, selective depletion in the post-transplant setting and the ex vivo expansion of antigen-specific T cells. For hematologic malignancies, cell therapy is contributing to enhanced clinical responses and overall survival and the immune response to cell therapy is predictive of response in multiple cancer types. In this review we summarize the available T cell therapeutics that do not rely on gene engineering for the treatment of patients with blood cancers.

Influence of Age on Acute and Chronic GVHD in Children Undergoing HLA-Identical Sibling Bone Marrow Transplantation for Acute Leukemia: Implications for Prophylaxis

Relapse remains the major cause of mortality after hematopoietic cell transplantation (HCT) for pediatric acute leukemia. Previous research has suggested that reducing the intensity of calcineurin inhibitor-based graft-versus-host disease (GVHD) prophylaxis may be an effective strategy for abrogating the risk of relapse in pediatric patients undergoing matched sibling donor (MSD) HCT. We reasoned that the benefits of this strategy could be maximized by selectively applying it to those patients least likely to develop GVHD. We conducted a study of risk factors for GVHD, to risk-stratify patients based on age. Patients age <18 years with leukemia who received myeloablative, T cell-replete MSD bone marrow transplantation and calcineurin inhibitor-based GVHD prophylaxis between 2000 and 2013 and were entered into the Center for International Blood and Marrow Transplant Research registry were included. The cumulative incidence of grade II-IV acute GVHD (aGVHD) was 19%, that of grade II-IV aGVHD 7%, and that of chronic GVHD (cGVHD) was 16%. Compared with age 13 to 18 years, age 2 to 12 years was associated with a lower risk of grade II-IV aGVHD (hazard ratio [HR], .42; 95% confidence interval [CI], .26 to .70; P = .0008), grade II-IV aGVHD (HR, .24; 95% CI, .10 to .56; P = .001), and cGVHD (HR, .32; 95% CI, .19 to .54; P < .001). Compared with 2000-2004, the risk of grade II-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .36; 95% CI, .20 to .65; P = .0007) and in 2009-2013 (HR, .24; 95% CI. .11 to .53; P = .0004). Similarly, the risk of grade III-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .23; 95% CI, .08 to .65; P = .0056) and 2009-2013 (HR, .16; 95% CI, .04 to .67; P = .0126) compared with those doing so in 2000-2004. We conclude that aGVHD rates have decreased significantly over time, and that children age 2 to 12 years are at very low risk for aGVHD and cGVHD. These results should be validated in an independent analysis, because these patients with high-risk malignancies may be good candidates for trials of reduced GVHD prophylaxis.

Intravital longitudinal wide-area imaging of dynamic bone marrow engraftment and multilineage differentiation through nuclear-cytoplasmic labeling

Bone marrow is a vital tissue that produces the majority of erythrocytes, thrombocytes, and immune cells. Bone marrow transplantation (BMT) has been widely performed in patients with blood disorders and cancers. However, the cellular-level behaviors of the transplanted bone marrow cells over wide-areas of the host bone marrow after the BMT are not fully understood yet. In this work, we performed a longitudinal wide-area cellular-level observation of the calvarial bone marrow after the BMT in vivo. Using a H2B-GFP/β-actin-DsRed double-transgenic mouse model as a donor, a subcellular-level nuclear-cytoplasmic visualization of the transplanted bone marrow cells was achieved, which enabled a direct in vivo dynamic monitoring of the distribution and proliferation of the transplanted bone marrow cells. The same spots in the wide-area of the calvarial bone marrow were repeatedly identified using fluorescently labeled vasculature as a distinct landmark. It revealed various dynamic cellular-level behaviors of the transplanted BM cells in early stage such as cluster formation, migration, and active proliferation in vivo.

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

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

Current Management of Childhood Acute Myeloid Leukemia

The outcome for children with acute myeloid leukemia (AML) has improved significantly over the past 30 years, with complete remission and overall survival rates exceeding 90 and 60%, respectively, in recent clinical trials. However, these improvements have not been achieved by the introduction of new agents. Instead, intensification of standard chemotherapy, more precise risk classification, improvements in supportive care, and the use of minimal residual disease to monitor response to therapy have all contributed to this success. Nevertheless, novel therapies are needed, as the cure rates for many subtypes of childhood AML remain unacceptably low. Here, we briefly review advances in our understanding of the biology and genetics of AML, the results of recent clinical trials, and current recommendations for the treatment of children with AML.

Cytogenetics and outcome of allogeneic transplantation in first remission of acute myeloid leukemia: the French pediatric experience

We analyzed the impact of cytogenetics on 193 children enrolled in two successive French trials (LAME89/91 and ELAM02), who received hematopoietic stem cell transplantation during CR1. Detailed karyotype was available for 66/74 (89%) in LAME89/91 and 118/119 (99%) in ELAM02. Several karyotype and transplant characteristics differed according to therapeutic protocol: unfavorable karyotypes were more frequent in ELAM02 (36% vs 18%), pretransplant chemotherapy included high-dose cytarabine in ELAM02 and not in LAME89/91, IV replaced oral busulfan in the conditioning regimen, methotrexate was removed from post-transplant immunosuppression, and matched unrelated donor and cord blood transplantation were introduced. Five-year overall survival (OS) was 78.2% in LAME89 and 81.4% in ELAM02. OS was significantly lower for the unfavorable cytogenetic risk group in LAME89/91 when compared with intermediate and favorable groups (50% vs 90.6 and 86.4%, P=0.001). This difference was no longer apparent in ELAM02 (80.9% vs 71.3% and 5/5, respectively). Survival improvement for children with unfavorable karyotype was statistically significant (P=0.026) and was due to decrease in relapse risk. Five-year transplantation-related mortality was 6.75% in LAME89/91. In ELAM02, it was 3.2% for patients with a sibling donor and 10.9% with an unrelated donor or cord blood. We conclude that the outcome of children with unfavorable karyotype transplanted in CR1 has improved.

An overview of the potential strategies for NK cell-based immunotherapy for acute myeloid leukemia

Patients with acute myeloid leukemia (AML) have relatively low survival rates compared to patients with other pediatric cancers. Relapse is frequent with conventional treatment and is a major cause of morbidity and mortality. Natural killer (NK) cells offer an alternative approach to chemotherapy that combats relapse by substantially eradicating AML blasts. New methods for enhancing NK cell activation and expression of the activating ligand on target malignant cells will increase the likelihood of success with this approach. We review these latest discoveries in NK cell-based therapy for AML and delineate recent advances in sensitizing AML cells to NK cell-mediated immunosurveillance.

Increased p53 protein expression as a potential predictor of early relapse after hematopoietic stem cell transplantation in children with acute myelogenous leukemia

Dysregulation of genes involved in the cell cycle such as TP53, P21, P16, and PTEN plays a key role in oncogenesis. We have earlier reported increased expression of the TP53 encoded protein p53, in bone marrow samples from pediatric patients with more aggressive, rare chronic myeloid malignancies. The aim of this study was to investigate protein expression of p53, p21, p16, and PTEN before and after HSCT in pediatric patients with AML and evaluate whether any potential alterations could predict relapse after HSCT. Paraffin-embedded bone marrow samples from 34 pediatric patients with AML were collected retrospectively from time of diagnosis as well as pre- and post-HSCT. IHC was performed on tissue microarrays with antibodies against p53, p21, p16, and PTEN. Study material was analyzed by independent t-tests and nonlinear regression. t-Tests showed a statistical significant difference in p53 (p = 0.010) with overexpression in the group of patients who relapsed compared to the relapse-free patients at >3-6 months post-HSCT. Analysis of p53 protein expression by IHC may be a potential predictor for relapse after HSCT in children with AML.

Minimal residual disease of leukemia and the quality of cryopreserved human ovarian tissue in vitro

Auto-transplant of cryopreserved ovarian tissue in leukemia patients carries a risk to reintroduce malignant cells. Maturation of ovarian follicles in vitro is a promising strategy to overcome the leukemic cell contamination. The follicle development and survival in 14 cryopreserved ovarian tissues with leukemia-specific PCR marker was evaluated after 7 or 14 days culture. Minimal residual disease (MRD) quantification was assessed by real-time quantitative PCR in order to identify the MRD positive (n = 6) and negative (n = 8) samples and to monitor levels of MRD before and after culture. The morphology of ovarian follicles were studied by light microscopy. After culture, no statistical significant differences were detected in follicle densities between MRD positive- and negative samples. Ovarian MRD either decreased below undetectable or fluctuated near the baseline level after 7 and 14 days in culture. This study provides quantitative in vitro evidence that leukemia contamination does not affect the follicle survival in cryopreserved ovarian tissue.

Similar outcomes of allogeneic hematopoietic cell transplantation from unrelated donor and umbilical cord blood vs. sibling donor for pediatric acute myeloid leukemia: Multicenter experience in China

In a multicenter study, we have conducted a retrospective study on 73 pediatric AML patients who were primary refractory or in greater than CR1 and investigated MSD (or MMSD) (n = 20), URD (n = 23), and UCB (n = 30) HCT between January 1998 and October 2009. The median day to neutrophil engraftment was similar in all groups. The median day to platelet engraftment was longer in the UCB group. The number of HLA mismatch was higher in the UCB group (p = 0.034); however, the cumulative incidence of grade III-IV aGVHD was not different among all groups (p = 0.125); furthermore, cGVHD was lower in the UCB group (p = 0.078). The risk of relapse did not differ among all groups (RR = 1.28, p = 0.125), but the patients of MSD (or MMSD) grafts had a trend of higher risk recurrence. Sixty-two patients survived with a median follow-up of 58.2 months. Five-yr LFS was 73.1%, 59.8%, and 59.6% for URD, UCB, and MSD (or MMDS), respectively (p = 0.426). Five-yr LFS in CR1 was 68.9%, with a significantly better result compared to 41.7% in CR2 (p = 0.025). Our comparisons suggest that pediatric AML patients receiving UCB had a higher early TRM, a lower cGVHD rate, and a similar long-term survival. The outcome of URD and UCB is comparable to that of a suitable sibling for pediatric AML.

Comparison of a fludarabine and melphalan combination-based reduced toxicity conditioning with myeloablative conditioning by radiation and/or busulfan in acute myeloid leukemia in Japanese children and adolescents

BACKGROUND

The relative efficacy of allogeneic hematopoietic cell transplantation (allo-HCT) after reduced toxicity conditioning (RTC) compared with standard myeloablative conditioning (MAC) in pediatric patients with acute myeloid leukemia (AML) has not been studied extensively. To address whether RTC is a feasible approach for pediatric patients with AML in remission, we performed a retrospective investigation of the outcomes of the first transplant in patients who had received an allo-HCT after RTC or standard MAC, using nationwide registration data collected between 2000 and 2011 in Japan.

PROCEDURE

We compared a fludarabine (Flu) and melphalan (Mel)-based regimen (RTC; n = 34) with total body irradiation (TBI) and/or busulfan (Bu)-based conditioning (MAC; n = 102) in demographic- and disease-criteria-matched childhood and adolescent patients with AML in first or second complete remission (CR1/CR2).

RESULTS

The incidence of engraftment, early complications, grade II-IV acute graft-versus-host disease (GVHD), and chronic GVHD were similar in each conditioning group. The risk of relapse (25% vs. 26%) and non-relapse mortality (13% vs. 11%) after 3 years did not differ between these groups, and univariate and multivariate analyses demonstrated that the 3-year overall survival (OS) rates after Flu/Mel-RTC and MAC were comparable (mean, 72% [range, 51-85%] and 68% [range, 58-77%], respectively).

CONCLUSIONS

The results suggest that the Flu/Mel-RTC regimen is a clinically acceptable conditioning strategy for childhood and adolescent patients with AML in remission. Although this retrospective, registry-based analysis has several limitations, RTC deserves to be further investigated in prospective trials.

New approaches for the immunotherapy of acute myeloid leukemia

Acute myeloid leukemia (AML) is a set of related diseases characterized by the immortalization and uncontrolled expansion of myeloid precursor cells. Core therapy for AML has remained unchanged for nearly 30 years, and survival rates remain unsatisfactory. However, advances in the immunotherapy of AML have created opportunities for improved outcomes. Enforcing a tumor-specific immune response through the re-direction of the adaptive immune system, which links remarkable specificity with potent cytotoxic effector functions, has proven particularly compelling. This may be coupled with immune checkpoint blockade and conventional therapies for optimal effect. Engineered antibodies are currently in use in AML and the repertoire of available therapeutics will expand. NK cells have shown effectiveness in this disease. New methods to optimize their activation and the targeting of AML show potential. Most significantly, adoptive immunotherapy with tumor-specific T cells, and particularly T cells re-directed using genetically introduced TCR or chimeric antigen receptors, have demonstrated promise. Each of these approaches has unique benefits and challenges that we explore in this review.

Treatment of Acute Myeloid Leukemia in Adolescent and Young Adult Patients

The objectives of this review were to discuss standard and investigational treatment strategies for adolescent and young adult with acute myeloid leukemia, excluding acute promyelocytic leukemia. Acute myeloid leukemia (AML) in adolescent and young adult patients (AYAs) may need a different type of therapy than those currently used in children and older patients. As soon as AML is diagnosed, AYA patient should be offered to participate in well-designed clinical trials. The standard treatment approach for AYAs with AML is remission induction chemotherapy with an anthracycline/cytarabine combination, followed by either consolidation chemotherapy or stem cell transplantation, depending on the ability of the patient to tolerate intensive treatment and cytogenetic features. Presently, continuing progress of novel drugs targeting specific pathways in acute leukemia may bring AML treatment into a new era.

Survival of Mexican children with acute myeloid leukaemia who received early intensification chemotherapy and an autologous transplant

Background. In Mexico and other developing countries, few reports of the survival of children with acute leukaemia exist. Objective. We aimed at comparing the disease-free survival of children with acute myeloid leukaemia who, in addition to being treated with the Latin American protocol of chemotherapy and an autologous transplant, either underwent early intensified chemotherapy or did not undergo such treatment. Procedure. This was a cohort study with a historical control group, forty patients, less than 16 years old. Group A (20 patients), diagnosed in the period 2005–2007, was treated with the Latin American protocol of chemotherapy with an autologous transplant plus early intensified chemotherapy: high doses of cytarabine and mitoxantrone. Group B (20 patients), diagnosed in the period 1999–2004, was treated as Group A, but without the early intensified chemotherapy. Results. Relapse-free survival for Group A was 90% whereas that for Group B it was 60% (P = 0.041). Overall survival for Group A (18, 90%) was higher than that for Group B (60%). Complete remission continued for two years of follow-up. Conclusions. Relapse-free survival for paediatric patients treated with the Latin American protocol of chemotherapy with an autologous transplant plus early intensified chemotherapy was higher than that for those who did not receive early intensified chemotherapy.

Hematopoietic cell transplantation and cellular therapeutics in the treatment of childhood malignancies

Hematopoietic cell transplantation (HCT) represents the most common and effective form of immunotherapy for childhood malignancies. The role of the graft-versus-leukemia effect in allogeneic HCT has been well established in childhood malignancies, but is also associated with short-term and long-term morbidity. HCT may be ineffective in some settings at obtaining control of the malignancy, and as such, cannot be used as a universal cancer immunotherapy. Novel therapies using dendritic cell vaccinations, tumor-infiltrating lymphocytes, and chimeric antigen receptor T cells are being evaluated as potential adjuvants to HCT.

Pediatric acute myeloid leukemia: biology and therapeutic implications of genomic variants

Acute myeloid leukemia (AML) is a molecularly heterogeneous disease and age-associated molecular alterations result in younger children harboring a distinct signature from older children and adolescents. Pediatric AML has a genetic and epigenetic profile with significant differences compared to adult AML. Somatic and epigenetic alterations contribute to myeloid leukemogenesis and can evolve from diagnosis to relapse. Cytogenetic alterations, somatic mutations and response to induction therapy are important in informing risk stratification and appropriate therapy allocation. Next-generation sequencing technologies are providing novel insights into the biology of AML and have the ability to identify potential targets for therapeutic intervention.

Reduced-toxicity myeloablative conditioning consisting of 8-Gy total body irradiation, cyclophosphamide and fludarabine for pediatric hematological malignancies

Conventional myeloablative conditioning (MAC) regimens often cause severe regimen-related toxicity (RRT). Furthermore, many patients suffer from poor quality of life in accordance with the increase in long-term survivors. We therefore devised a reduced-toxicity myeloablative conditioning (RTMAC) regimen consisting of 8-Gy total body irradiation (TBI), fludarabine (FLU) and cyclophosphamide (CY) for pediatric hematological malignancies. A retrospective single-center analysis was performed on patients with leukemia or myelodysplastic syndrome (MDS), aged ≤20 years, who had received an 8-Gy TBI/FLU/CY RTMAC regimen followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT). Thirty-one patients underwent first allo-HSCT after an RTMAC regimen. The diagnoses were acute lymphoblastic leukemia (n = 11), acute myeloid leukemia (n = 13), MDS (n = 4), juvenile myelomonocytic leukemia (n = 1) and acute leukemias of ambiguous lineage (n = 2). While 3 patients showed early hematological relapse, the remaining 28 patients achieved engraftments. None of the patients developed grade 4 or 5 toxicities during the study period. The 5-year overall survival and relapse-free survival were 80% [95% confidence interval: CI, 61-91%] and 71% [95% CI, 52-84%], respectively. Our RTMAC regimen would be less toxic and offers a high probability of survival for children with hematological malignancies.