Outcome of children with high-risk acute myeloid leukemia given autologous or allogeneic hematopoietic cell transplantation in the aieop AML-2002/01 study

Pediatric chronic graft-versus-host disease-related dry eye disease and the diagnostic association of potential clinical findings

Pediatric graft-versus-host-disease (GVHD)-related dry eye disease (DED) is often overlooked due to a lack of subjective symptoms and reliable testing, leading to irreversible corneal damage. To study the clinical findings contributing to the accurate detection of pediatric GVHD-related DED, a retrospective study of pediatric patients treated with hematopoietic stem cell transplantation (HSCT) at Keio University Hospital between 2004 and 2017 was conducted. Association and diagnostic values of ophthalmological findings for DED were analyzed. Twenty-six patients who had no ocular complications before HSCT were included in the study. Eleven (42.3%) patients developed new-onset DED. The cotton thread test showed excellent diagnostic accuracy in detecting DED (area under the receiver operating curve, 0.96; sensitivity, 0.95; specificity, 0.85) with a cut-off of 17 mm, which was higher than the conventional threshold of 10 mm. Additionally, the presence of filamentary keratitis (FK) and pseudomembranous conjunctivitis (PC) were significantly associated with the diagnosis of DED (p value, 0.003 and 0.001 for FK and PC, respectively) and displayed good diagnostic performance (sensitivity, 0.46 and 0.54; specificity, 0.97 and 0.97 for FK and PC, respectively). In conclusion, the cotton thread test with a new threshold, the presence of PC and FK, could be helpful for promptly detecting pediatric GVHD-related DED.

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.

Molecular Measurable Residual Disease Assessment before Hematopoietic Stem Cell Transplantation in Pediatric Acute Myeloid Leukemia Patients: A Retrospective Study by the I-BFM Study Group

Hematopoietic stem cell transplantation (HSCT) is a curative post-remission treatment in patients with acute myeloid leukemia (AML), but relapse after transplant is still a challenging event. In recent year, several studies have investigated the molecular minimal residual disease (qPCR-MRD) as a predictor of relapse, but the lack of standardized protocols, cut-offs, and timepoints, especially in the pediatric setting, has prevented its use in several settings, including before HSCT. Here, we propose the first collaborative retrospective I-BFM-AML study assessing qPCR-MRD values in pretransplant bone marrow samples of 112 patients with a diagnosis of AML harboring t(8;21)(q22; q22)RUNX1::RUNX1T1, or inv(16)(p13q22)CBFB::MYH11, or t(9;11)(p21;q23)KMT2A::MLLT3, or FLT3-ITD genetic markers. We calculated an ROC cut-off of 2.1 × 10⁻⁴ that revealed significantly increased OS (83.7% versus 57.1%) and EFS (80.2% versus 52.9%) for those patients with lower qPCR-MRD values. Then, we partitioned patients into three qPCR-MRD groups by combining two different thresholds, 2.1 × 10⁻⁴ and one lower cut-off of 1 × 10⁻², and stratified patients into low-, intermediate-, and high-risk groups. We found that the 5-year OS (83.7%, 68.6%, and 39.2%, respectively) and relapse-free survival (89.2%, 73.9%, and 67.9%, respectively) were significantly different independent of the genetic lesion, conditioning regimen, donor, and stem cell source. These data support the PCR-based approach playing a clinical relevance in AML transplant management.

Pediatric Acute Myeloid Leukemia—Past, Present, and Future

This review reports about the main steps of development in pediatric acute myeloid leukemia (AML) concerning diagnostics, treatment, risk groups, and outcomes. Finally, a short overview of present and future approaches is given.

Clofarabine-fludarabine-busulfan in HCT for pediatric leukemia: an effective, low toxicity, TBI-free conditioning regimen

CloFluBu-conditioning results in encouraging EFS for ALL and AML, with low TRM, limited incidence of aGvHD and GF, and no cases of VOD.

Minimal residual disease status prior to transplantation impacted outcome due to increased relapse risk in both AML and ALL patients.

We prospectively studied clofarabine-fludarabine-busulfan (CloFluBu)-conditioning in allogeneic hematopoietic cell therapy (HCT) for lymphoid and myeloid malignancies and hypothesized that CloFluBu provides a less toxic alternative to conventional conditioning regimens, with adequate antileukemic activity. All patients receiving their first HCT, from 2011-2019, were included and received CloFluBu. The primary endpoint was event-free survival (EFS). Secondary endpoints were overall survival (OS), graft-versus-host disease (GvHD)-relapse-free survival (GRFS), treatment-related mortality (TRM), cumulative incidence of relapse (CIR), acute and chronic GvHD (aGvHD and cGvHD), and veno-occlusive disease (VOD). Cox proportional hazard and Fine and Gray competing-risk models were used for data analysis. One hundred fifty-five children were included: 60 acute lymphoid leukemia (ALL), 69 acute myeloid leukemia (AML), and 26 other malignancies (mostly MDS-EB). The median age was 9.7 (0.5 to 18.6) years. Estimated 2-year EFS was 72.0% ± 6.0 in ALL patients, and 62.4% ± 6.0 in AML patients. TRM in the whole cohort was 11.0% ± 2.6, incidence of aGvHD 3 to 4 at 6 months was 12.3% ± 2.7, extensive cGvHD at 2 years was 6.4% ± 2.1. Minimal residual disease-positivity prior to HCT was associated with higher CIR, both in ALL and AML. CloFluBu showed limited toxicity and encouraging EFS. CloFluBu is a potentially less toxic alternative to conventional conditioning regimens. Randomized prospective studies are needed.

Advances in the First Line Treatment of Pediatric Acute Myeloid Leukemia in the Polish Pediatric Leukemia and Lymphoma Study Group from 1983 to 2019

Simple Summary

We retrospectively analyzed the results of the five consecutive treatment protocols for pediatric acute myeloid leukemia (AML) used in Poland from 1983 to 2019 (excluding promyelocytic, secondary, biphenotypic, and Down syndrome AML). The study included 899 children. The probability of three-year overall, event-free, and relapse-free survival increased from 0.34 ± 0.03 to 0.75 ± 0.05, 0.31 ± 0.03 to 0.67 ± 0.05, and 0.52 ± 0.03 to 0.78 ± 0.05, respectively. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24) who were treated in the AML-BFM 2012 Registry, while an unsatisfactory outcome was found in patients with FLT3-ITD. The use of standardized therapeutic protocols with the successive consideration of genetic prognostic factors and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.

Abstract

Background: From 1983, standardized therapeutic protocols for pediatric acute myeloid leukemia (AML) based on the BFM group experience were introduced in Poland. We retrospectively analyzed the results of pediatric AML treatment in Poland from 1983 to 2019 (excluding promyelocytic, therapy-related, biphenotypic, and Down syndrome AML). Methods: The study included 899 children suffering from AML treated with the following: AML-PPPLBC 83 (1983–1993, n = 187), AML-PPGLBC 94 (1994–1997, n = 74), AML-PPGLBC 98 (1998–2004, n = 151), AML-BFM 2004 Interim (2004–2015, n = 356), and AML-BFM 2012 (2015–2019, n = 131). Results: The probability of three-year overall survival was 0.34 ± 0.03, 0.37 ± 0.05, 0.54 ± 0.04, 0.67 ± 0.03, and 0.75 ± 0.05; event-free survival was 0.31 ± 0.03, 0.34 ± 0.05, 0.44 ± 0.04, 0.53 ± 0.03, and 0.67 ± 0.05; and relapse-free survival was 0.52 ± 0.03, 0.65 ± 0.05, 0.58 ± 0.04, 0.66 ± 0.03, and 0.78 ± 0.05, respectively, in the subsequent periods. A systematic reduction of early deaths and deaths in remission was achieved, while the percentage of relapses decreased only in the last therapeutic period. Surprisingly good results were obtained in the group of patients treated with AML-BFM 2012 with unfavorable genetic abnormalities like KMT2A-MLLT10/t(10;11)(p12;q23) and DEK-NUP214/t(6;9)(p23;q24), while unsatisfactory outcomes were found in the patients with FLT3-ITD. Conclusions: The use of standardized, systematically modified therapeutic protocols, with the successive consideration of genetic prognostic factors, and advances in supportive care led to a significant improvement in AML treatment outcomes over the last 40 years.

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.

Impact of a Bayesian Individualization of Cyclosporine Dosage Regimen for Children Undergoing Allogeneic Hematopoietic Cell Transplantation: A Cost-Effectiveness Analysis

BACKGROUND

Cyclosporine A (CsA) is the main drug used to prevent graft-versus-host disease in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). CsA therapeutic drug monitoring (TDM) has been performed for ages, with studies revealing clinical benefits, but failing to examine its economic impact. In this article, the main objective was to evaluate the economic impact of the CsA TDM strategy, based on a Bayesian approach, by assessing costs related to its clinical impact. Furthermore, TDM effectiveness was analyzed for pharmacokinetics and clinical outcomes.

METHODS

A cost-effective, nonrandomized, retrospective, single-center study compared 2 CsA monitoring and dose adaptation strategies in pediatric patients undergoing HSCT. From 2014 to 2016, CsA TDM was performed using a population pharmacokinetics model-coupled Bayesian approach by a pharmacist ["pharmacist-assisted individualization" (PAI)]. From 2017 to 2018, CsA TDM was performed by the clinician without a Bayesian approach (non-PAI group). HSCT costs were evaluated from the French National Insurance perspective. Economic and clinical outcomes were assessed by measuring incremental cost-effectiveness ratios.

RESULTS

The study included 144 patients: 90 and 54 patients in PAI and non-PAI groups, respectively. Both groups were comparable for sociodemographic and clinical characteristics. The mean total cost per patient was significantly lower (P < 0.01) in the PAI group (€85,947) than in the non-PAI group (€100,435). Multivariate analysis revealed that TDM based on the Bayesian approach was a protective factor (odds ratio = 0.86) for severe acute graft-versus-host disease. We noted that pharmacist-based TDM was the dominant strategy. Bayesian method-based TDM allowed an increase in the percentage of target attainment at any period post-HSCT.

CONCLUSIONS

CsA TDM with a Bayesian approach is a cost-effective procedure, and highlighted clinical benefits encourage the development of new TDM strategies for HSCT.

Exploiting Clonal Evolution to Improve the Diagnosis and Treatment Efficacy Prediction in Pediatric AML

Despite improvements in therapeutic protocols and in risk stratification, acute myeloid leukemia (AML) remains the leading cause of childhood leukemic mortality. Indeed, the overall survival accounts for ~70% but still ~30% of pediatric patients experience relapse, with poor response to conventional chemotherapy. Thus, there is an urgent need to improve diagnosis and treatment efficacy prediction in the context of this disease. Nowadays, in the era of high throughput techniques, AML has emerged as an extremely heterogeneous disease from a genetic point of view. Different subclones characterized by specific molecular profiles display different degrees of susceptibility to conventional treatments. In this review, we describe in detail this genetic heterogeneity of pediatric AML and how it is linked to relapse in terms of clonal evolution. We highlight some innovative tools to characterize minor subclones that could help to enhance diagnosis and a preclinical model suitable for drugs screening. The final ambition of research is represented by targeted therapy, which could improve the prognosis of pediatric AML patients, as well as to limit the side toxicity of current treatments.

Acute Leukemia in Infants

PURPOSE OF THE REVIEW

Infant leukemia is a rare, distinct subgroup of pediatric acute leukemias diagnosed in children under 1 year of age and characterized by unique, aggressive biology. Here, we review its clinical presentation, underlying molecular biology, current treatment strategies, and novel therapeutic approaches.

RECENT FINDINGS

Infant leukemias are associated with high-risk molecular features and high rates of chemotherapy resistance. International collaborative clinical trials have led to better understanding of the underlying molecular biology, refined risk-based stratification, and investigated the use of hematopoietic stem cell transplantation. However, intensification of chemotherapy has failed to improve outcomes, and current regimens are associated with significant treatment-related and long-term toxicities. Infants with leukemia remain a challenging group to treat. We must continue collaborative efforts to move beyond traditional cytotoxic chemotherapy, incorporate molecularly targeted strategies and immunotherapy, and increase access to clinical trials to improve outcomes for this high-risk group of patients.

Treatment Outcomes of Pediatric Acute Myeloid Leukemia in the Yeungnam Region: A Multicenter Retrospective Study of the Study Alliance of Yeungnam Pediatric Hematology-Oncology (SAYPH)

Acute myeloid leukemia (AML) is the second most common pediatric leukemia, with a survival rate of 70%. In this retrospective study, we evaluated the treatment outcomes of pediatric AML among 144 patients diagnosed between 2000 and 2013. After induction, 80.6% of patients achieved complete remission (CR). The 5-year overall survival (OS) and event-free survival (EFS) rates were 58.8 ± 4.2% and 49.8 ± 4.2%, respectively. Based on the response to induction therapy, the 5-year OS was 66.9 ± 5.7% in patients with CR (p < 0.001). Ninety-nine patients with CR after induction therapy were examined, and their 5-year OS and EFS were 66.4 ± 4.9% and 56.3 ± 5.1%, respectively. The 5-year OS rates according to treatment were 59.9 ± 7.4% in the chemotherapy group and 72.3 ± 6.3% in the hematopoietic stem cell transplantation (HSCT) group (p = 0.089). The EFS was 50.1 ± 7.4% in the chemotherapy group and 61.7 ± 6.9% in the HSCT group (p = 0.098). OS and EFS according to cytogenetics were insignificant. Our findings confirmed that the response to induction treatment was important for survival and HSCT had no significant survival benefits compared with those of chemotherapy. Moreover, many early induction deaths under the age of 2 years were observed.

Clinical Grade Production of Wilms' Tumor-1 Loaded Cord Blood-Derived Dendritic Cells to Prevent Relapse in Pediatric AML After Cord Blood Transplantation

Hematopoietic cell transplantation (HCT) is a last resort, potentially curative treatment option for pediatric patients with refractory acute myeloid leukemia (AML). Cord blood transplantation (CBT) results in less relapses and less graft-versus-host disease when compared to other sources. Nevertheless, still more than half of the children die from relapses. We therefore designed a strategy to prevent relapses by inducing anti-AML immunity after CBT, using a CB-derived dendritic cell (CBDC) vaccine generated from CD34+ CB cells from the same graft. We here describe the optimization and validation of good manufacturing practice (GMP)-grade production of the CBDC vaccine. We show the feasibility of expanding low amounts of CD34+ cells in a closed bag system to sufficient DCs per patient for at least three rounds of vaccinations. The CBDCs showed upregulated costimulatory molecules after maturation and showed enhanced CCR7-dependent migration toward CCL19 in a trans-well migrations assay. CBDCs expressed Wilms’ tumor 1 (WT1) protein after electroporation with WT1-mRNA, but were not as potent as CBDCs loaded with synthetic long peptides (peptivator). The WT1-peptivator loaded CBDCs were able to stimulate T-cells both in a mixed lymphocyte reaction as well as in an antigen-specific (autologous) setting. The autologous stimulated T-cells lysed not only the WT1+ cell line, but most importantly, also primary pediatric AML cells. Altogether, we provide a GMP-protocol of a highly mature CBDC vaccine, loaded with WT1 peptivator and able to stimulate autologous T-cells in an antigen-specific manner. Finally, these T-cells lysed primary pediatric AML demonstrating the competence of the CBDC vaccine strategy.

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.

Allogeneic Hematopoietic Stem Cell Transplantation for Children and Adolescents with Acute Myeloid Leukemia in Brazil: A Multicentric Retrospective Study

The survival rates of children with high-risk acute myeloid leukemia (AML) treated with hematopoietic stem cell transplant (HSCT) range from 60% to 70% in high-income countries. The corresponding rate for Brazilian children with AML who undergo HSCT is unknown. We conducted a retrospective analysis of 114 children with AML who underwent HSCT between 2008 and 2012 at institutions participating in the Brazilian Pediatric Bone Marrow Transplant Working Group. At transplant, 38% of the children were in first complete remission (CR1), 37% were in CR2, and 25% were in CR3+ or had persistent disease. The donors included 49 matched-related, 59 matched-unrelated, and six haploidentical donors. The most frequent source of cells was bone marrow (69%), followed by the umbilical cord (19%) and peripheral blood (12%). The 4-year overall survival was 47% (95% confidence interval [CI] 30%–57%), and the 4-year progression-free survival was 40% (95% CI 30%–49%). Relapse occurred in 49 patients, at a median of 122 days after HSCT. There were 65 deaths: 40 related to AML, 19 to infection, and six to graft versus host disease. In conclusion, our study suggests that HSCT outcomes for children with AML in CR1 or CR2 are acceptable and that this should be considered in the overall treatment planning for children with AML in Brazil. Therapeutic standardization through the adoption of multicentric protocols and appropriate supportive care treatment will have a significant impact on the results of HSCT for AML in Brazil and possibly in other countries with limited resources.

Haploidentical- versus identical-sibling transplant for high-risk pediatric AML: A multi-center study

Background

Human leukocyte antigen‐identical sibling donor (ISD)‐hematopoietic stem cell transplantation (SCT) is a potentially curative treatment for high‐risk pediatric acute myeloid leukemia (AML). A haploidentical donor (HID) is readily available to almost all children. Previous studies have demonstrated that patients with HID‐SCT had similar outcomes compared to ISD‐SCT for pediatric and adult AML. However, the role of HID‐SCT in high‐risk pediatric AML is unclear.

Methods

To compare the overall survival of high‐risk AML children who underwent either HID‐SCT or ISD‐SCT, we analyzed 179 cases of high‐risk AML patients under 18 years of age treated with either ISD‐SCT (n = 23) or HID‐SCT (n = 156). Granulocyte colony‐stimulating factor plus anti‐thymocyte globulin‐based regimens were used for HID‐SCT. We also analyzed the subgroup data of AML patients at first complete remission (CR1) before SCT with known cytogenetic risk.

Results

The numbers of adverse cytogenetic risk recipients were 8 (34.8%) and 13 (18.8%) in the ISD‐SCT group and the HID‐SCT group, and the number of patients with disease status beyond CR1 were 6 (26.1%) and 14 (20.3%) in the two groups. The cumulative rates of grades II‐IV acute graft‐versus‐host disease (GVHD) were 13.0% in the ISD‐SCT group and 34.8% in the HID‐SCT group (P = 0.062), with a three‐year cumulative rates of chronic GVHD at 14.1% and 34.9%, respectively (P = 0.091). The relapse rate in the ISD‐SCT group was significantly higher than that in the HID‐SCT group (39.1% vs. 16.4%, P = 0.027); with non‐relapse mortality at 0.0% and 10.6% (P = 0.113), respectively. The three‐year overall survival rates were 73.0% for the ISD‐SCT group and 74.6% for the HID‐SCT group (P = 0.689). In subgroup analysis, the three‐year relapse rate in the ISD‐SCT group was higher than that in the HID‐SCT group (50.0% vs. 9.2%, P = 0.001) and the three‐year DFS in the ISD‐SCT group (50.0%) was lower than that in the HID‐SCT group (81.2%) (P = 0.021).

Conclusions

Unmanipulated HID‐SCT achieved DFS and OS outcomes comparable to those of ISD‐SCT for high‐risk pediatric AML patients with potentially higher rate but manageable GVHD.

Minor Histocompatibility Antigen-Specific T Cells

Minor Histocompatibility (H) antigens are major histocompatibility complex (MHC)/Human Leukocyte Antigen (HLA)-bound peptides that differ between allogeneic hematopoietic stem cell transplantation (HCT) recipients and their donors as a result of genetic polymorphisms. Some minor H antigens can be used as therapeutic T cell targets to augment the graft-vs.-leukemia (GVL) effect in order to prevent or manage leukemia relapse after HCT. Graft engineering and post-HCT immunotherapies are being developed to optimize delivery of T cells specific for selected minor H antigens. These strategies have the potential to reduce relapse risk and thereby permit implementation of HCT approaches that are associated with less toxicity and fewer late effects, which is particularly important in the growing and developing pediatric patient. Most minor H antigens are expressed ubiquitously, including on epithelial tissues, and can be recognized by donor T cells following HCT, leading to graft-vs.-host disease (GVHD) as well as GVL. However, those minor H antigens that are expressed predominantly on hematopoietic cells can be targeted for selective GVL. Once full donor hematopoietic chimerism is achieved after HCT, hematopoietic-restricted minor H antigens are present only on residual recipient malignant hematopoietic cells, and these minor H antigens serve as tumor-specific antigens for donor T cells. Minor H antigen-specific T cells that are delivered as part of the donor hematopoietic stem cell graft at the time of HCT contribute to relapse prevention. However, in some cases the minor H antigen-specific T cells delivered with the graft may be quantitatively insufficient or become functionally impaired over time, leading to leukemia relapse. Following HCT, adoptive T cell immunotherapy can be used to treat or prevent relapse by delivering large numbers of donor T cells targeting hematopoietic-restricted minor H antigens. In this review, we discuss minor H antigens as T cell targets for augmenting the GVL effect in engineered HCT grafts and for post-HCT immunotherapy. We will highlight the importance of these developments for pediatric HCT.

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.

Current status of umbilical cord blood transplantation in children

The first umbilical cord blood (UCB) transplantation was performed 30 years ago. UCB transplantation (UCBT) is now widely used in children with malignant and non-malignant disorders who lack a matched family donor. UCBT affords a lower incidence of graft-versus-host disease compared to alternative stem cell sources, but also presents a slower immune recovery and a high risk of infections if serotherapy is not omitted or targeted within the conditioning regimen. The selection of UCB units with high cell content and good human leucocyte antigen match is essential to improve the outcome. Techniques, such as double UCBT, ex vivo stem cell expansion and intra-bone injection of UCB, have improved cord blood engraftment, but clinical benefit remains to be demonstrated. Cell therapies derived from UCB are under evaluation as potential novel strategies to reduce relapse and viral infections following transplantation. In recent years, improvements within haploidentical transplantation have reduced the overall use of UCBT as an alternative stem cell source; however, each may have its relative merits and disadvantages and tailored use of these alternative stem cell sources may be the optimal approach.

Clinical and biological features of paediatric acute myeloid leukaemia (AML) with primary induction failure in the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study

The prognosis of paediatric acute myeloid leukaemia (AML) with primary induction failure (PIF) is extremely poor, and effective treatment strategies have not been established. We investigated the clinical and biological features of paediatric AML patients with PIF registered to the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study. The 3-year overall survival rate of the 41 PIF patients was 19.0%. High leucocyte count, M7 morphology, and unfavourable genetic aberrations, such as FLT3-internal tandem duplication, NUP98-NSD1 and high MECOM or PRDM16 expression, were risk factors for PIF. More effective treatment strategies based on leukaemia biology need to be urgently explored.

Targeted Therapies for Pediatric AML: Gaps and Perspective

Acute myeloid leukemia (AML) is a hematopoietic disorder characterized by numerous cytogenetic and molecular aberrations that accounts for ~25% of childhood leukemia diagnoses. The outcome of children with AML has increased remarkably over the past 30 years, with current survival rates up to 70%, mainly due to intensification of standard chemotherapy and improvements in risk classification, supportive care, and minimal residual disease monitoring. However, childhood AML prognosis remains unfavorable and relapse rates are still around 30%. Therefore, novel therapeutic approaches are needed to increase the cure rate. In AML, the presence of gene mutations and rearrangements prompted the identification of effective targeted molecular strategies, including kinase inhibitors, cell pathway inhibitors, and epigenetic modulators. This review will discuss several new drugs that recently received US Food and Drug Administration approval for AML treatment and promising strategies to treat childhood AML, including FLT3 inhibitors, epigenetic modulators, and Hedgehog pathway inhibitors.

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.

Survival and Late Effects after Allogeneic Hematopoietic Cell Transplantation for Hematologic Malignancy at Less than Three Years of Age

Very young children undergoing hematopoietic cell transplantation (HCT) are a unique and vulnerable population. We analyzed outcomes of 717 patients from 117 centers who survived relapse free for ≥1 year after allogeneic myeloablative HCT for hematologic malignancy at <3 years of age, between 1987 and 2012. The median follow-up was 8.3 years (range, 1.0 to 26.4 years); median age at follow-up was 9 years (range, 2 to 29 years). Ten-year overall and relapse-free survival were 87% (95% confidence interval [CI], 85% to 90%) and 84% (95% CI, 81% to 87%). Ten-year cumulative incidence of relapse was 11% (95% CI, 9% to 13%). Of 84 deaths, relapse was the leading cause (43%). Chronic graft-versus-host-disease 1 year after HCT was associated with increased risk of mortality (hazard ratio [HR], 2.1; 95% CI, 1.3 to 3.3; P = .0018). Thirty percent of patients experienced ≥1 organ toxicity/late effect >1 year after HCT. The most frequent late effects included growth hormone deficiency/growth disturbance (10-year cumulative incidence, 23%; 95% CI, 19% to 28%), cataracts (18%; 95% CI, 15% to 22%), hypothyroidism (13%; 95% CI, 10% to 16%), gonadal dysfunction/infertility requiring hormone replacement (3%; 95% CI, 2% to 5%), and stroke/seizure (3%; 95% CI, 2% to 5%). Subsequent malignancy was reported in 3.6%. In multivariable analysis, total body irradiation (TBI) was predictive of increased risk of cataracts (HR, 17.2; 95% CI, 7.4 to 39.8; P < .001), growth deficiency (HR, 3.5; 95% CI, 2.2 to 5.5; P < .001), and hypothyroidism (HR, 5.3; 95% CI, 3.0 to 9.4; P < .001). In summary, those who survived relapse free ≥1 year after HCT for hematologic malignancy at <3 years of age had favorable overall survival. Chronic graft-versus-host-disease and TBI were associated with adverse outcomes. Future efforts should focus on reducing the risk of relapse and late effects after HCT at early age.

Visual evoked potentials after hematopoietic allogeneic stem cell transplantation in childhood

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VEP recordings were abnormal in 17% of the patients median 6 years post hematopoietic stem cell transplantation in childhood.

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Pathological VEPs were associated with decreased visual acuity.

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Pathological VEPs were not linked to irradiation, chemotherapy or malignant diagnosis.

Objective

To study visual pathway pathology detected by visual evoked potentials (VEPs) in patients treated with hematopoietic stem cell transplantation (HSCT) in childhood and to determine the impact of adverse ocular findings, somatic diseases, and conditioning regimens on the VEP results.

Methods

Ophthalmological assessments including pattern VEPs were performed in 47 of 79 patients at a median age of 15 years (range 3–21 years) in median 6 years (1–17 years) after HSCT. Somatic data were extracted from medical records.

Results

Eight patients of 47 (17%) demonstrated pathological VEPs with prolonged latencies bilaterally (n = 3) or unilaterally (n = 5) at their latest VEP test at an age of 12–18 years. A subnormal visual acuity was present in 8/11 eyes with pathological VEPs: one eye had cataract, six eyes had cataract surgery where of two had developed secondary cataracts. One eye had residual retinopathy of prematurity. Pathological VEPs were associated with decreased visual acuity (p = 0.00019) but not linked to gender, malignant diagnosis or conditioning.

Conclusion

VEP recordings showed an association with decreased visual acuity but no relationship with irradiation or chemotherapy in the present study.

Significance

VEP recordings might be of clinical value for children with an unexplained subnormal visual acuity undergoing HSCT.

Impact of Conditioning Regimen on Outcomes for Children with Acute Myeloid Leukemia Undergoing Transplantation in First Complete Remission. An Analysis on Behalf of the Pediatric Disease Working Party of the European Group for Blood and Marrow Transplantation

Hematopoietic stem cell transplantation (HSCT) represents the cornerstone of treatment in pediatric high-risk and relapsed acute myeloid leukemia (AML). The aim of the present study was to compare outcomes of pediatric patients with AML undergoing HSCT using 3 different conditioning regimens: total body irradiation (TBI) and cyclophosphamide (Cy); busulfan (Bu) and Cy; or Bu, Cy, and melphalan (Mel). In this retrospective study, registry data for patients > 2 and <18 years age undergoing matched allogeneic HSCT for AML in first complete remission (CR1) in 204 European Group for Blood and Marrow Transplantation centers between 2000 and 2010 were analyzed. Data were available for 631 patients; 458 patients received stem cells from a matched sibling donor and 173 from a matched unrelated donor. For 440 patients, bone marrow was used as stem cell source, and 191 patients received peripheral blood stem cells. One hundred nine patients received TBICy, 389 received BuCy, and 133 received BuCyMel as their preparatory regimen. Median follow-up was 55 months. Patients receiving BuCyMel showed a lower incidence of relapse at 5 years (14.7% versus 31.5% in BuCy versus 30% in TBICy, P < .01) and higher overall survival (OS) (76.6% versus 64% versus 64.5%, P = .04) and leukemia-free survival (LFS) (74.5% versus 58% versus 61.9%, P < .01), with a comparable nonrelapse mortality (NRM) (10.8% versus 10.5% versus 8.1%, P = .79). Acute graft-versus-host disease (GVHD) grades III and IV but not chronic GVHD, was higher in patients receiving BuCyMel. Older age at HSCT had an adverse impact on NRM and the use of peripheral blood as stem cell source was associated with increased chronic GVHD and NRM as well as lower LFS and OS. Among pediatric patients receiving HSCT for AML in CR1, the use of BuCyMel conditioning proved superior to TBICy and BuCy in reducing relapse and improving LFS.

Cognate HLA absence in trans diminishes human NK cell education

NK cells are innate lymphocytes with protective functions against viral infections and tumor formation. Human NK cells carry inhibitory killer cell Ig-like receptors (KIRs), which recognize distinct HLAs. NK cells with KIRs for self-HLA molecules acquire superior cytotoxicity against HLA- tumor cells during education for improved missing-self recognition. Here, we reconstituted mice with human hematopoietic cells from donors with homozygous KIR ligands or with a mix of hematopoietic cells from these homozygous donors, allowing assessment of the resulting KIR repertoire and NK cell education. We found that co-reconstitution with 2 KIR ligand-mismatched compartments did not alter the frequency of KIR-expressing NK cells. However, NK cell education was diminished in mice reconstituted with parallel HLA compartments due to a lack of cognate HLA molecules on leukocytes for the corresponding KIRs. This change in NK cell education in mixed human donor-reconstituted mice improved NK cell-mediated immune control of EBV infection, indicating that mixed hematopoietic cell populations could be exploited to improve NK cell reactivity against leukotropic pathogens. Taken together, these findings indicate that leukocytes lacking cognate HLA ligands can disarm KIR+ NK cells in a manner that may decrease HLA- tumor cell recognition but allows for improved NK cell-mediated immune control of a human γ-herpesvirus.

Characterization of children with FLT3-ITD acute myeloid leukemia: a report from the AIEOP AML-2002 study group

Recurrent molecular markers have been routinely used in acute myeloid leukemia (AML) for risk assessment at diagnosis, whereas their post-induction monitoring still represents a debated issue. We evaluated the prognostic value and biological impact of minimal residual disease (MRD) and of the allelic ratio (AR) of FLT3-internal-tandem duplication (ITD) in childhood AML. We retrospectively screened 494 children with de novo AML for FLT3-ITD mutation, identifying 54 harboring the mutation; 51% of them presented high ITD-AR at diagnosis and had worse event-free survival (EFS, 19.2 versus 63.5% for low ITD-AR, <0.05). Forty-one percent of children with high levels of MRD after the 1st induction course, measured by a patient-specific real-time-PCR, had worse EFS (22.2 versus 59.4% in low-MRD patients, P<0.05). Next, we correlated these parameters with gene expression, showing that patients with high ITD-AR or persistent MRD had characteristic expression profiles with deregulated genes involved in methylation and acetylation. Moreover, patients with high CyclinA1 expression presented an unfavorable EFS (20.3 versus 51.2% in low CyclinA1 group, P<0.01). Our results suggest that ITD-AR levels and molecular MRD should be considered in planning clinical management of FLT3-ITD patients. Different transcriptional activation of epigenetic and oncogenic profiles may explain variability in outcome among these patients, for whom novel therapeutic approaches are desirable.

Haploidentical hematopoietic stem cell transplantation without total body irradiation for pediatric acute leukemia: a single-center experience

Hematopoietic stem cell transplantation (HSCT) is a promising method for therapy of pediatric patients with acute leukemia. However, less availability of matched donors limited its wide application. Recently, haploidentical HSCT has become a great resource. Here, we have retrospectively reported our experience of 20 pediatric patients with acute leukemia who underwent haploidentical HSCT without total body irradiation (TBI) myeloablative regimen in our center from November 2007 to June 2014. All the patients attained successful HSCT engraftment in terms of myeloid and platelet recovery. Thirteen patients developed grade I–IV acute graft-versus-host disease (a-GVHD). The incidence of grade I–II a-GVHD, grade III–IV a-GVHD, and chronic GVHD (c-GVHD) was 45%, 20%, and 25%, respectively. The mean myeloid and platelet recovery time was 13.20±2.41 and 19.10±8.37 days. The median follow-up time was 43.95±29.26 months. During the follow-up, three patients died. The overall survival (OS) rate was 85%. The present study indicated that haploidentical HSCT without TBI myeloablative regimen significantly improved the OS rate of pediatric patients with acute leukemia.

TCR-alpha/beta and CD19 depletion and treosulfan-based conditioning regimen in unrelated and haploidentical transplantation in children with acute myeloid leukemia

We evaluated the depletion of TCR-alpha/beta cells from the graft of children with high-risk AML, who received transplantation from unrelated (n=20) and haploidentical donors (n=13). The preparative regimen included treosulfan, melphalan, fludarabine and anti-thymocyte globulin. Grafts were PBSC engineered by TCR-alpha/beta and CD19 depletion. The graft contained a median of 9 × 10(6)/kg of CD34+ and 20 × 10(3)/kg of αβ-T cells. Post-transplant immune suppression included tacrolimus till day +30 and Mtx in 21 patients, tacrolimus in 5, Mtx in 2 and no prophylaxis in 5 patients. Sixteen patients received native or TCR-alpha/beta-depleted donor lymphocytes at a median of 47 (40-204) days. Median follow-up is 1.76 years. Primary engraftment was achieved in 33 patients (100%). Cumulative incidence of acute GvHD (aGvHD) grade 2-3 was 39 (26-60)%, half of them had skin-only aGvHD. Cumulative incidence of chronic GvHD was 30(18-50)%. Transplant-related mortality is 10(4-26)%. Event-free survival (EFS) is 60(43-76)% and overall survival (OS) is 67(50-84)% at 2 years. In a subgroup of patients, who received transplantation in CR, EFS is 66(48-84)% and OS-72(53-90)% at 2 years. Our data suggest that TCR-alpha/beta and CD19 depletion is a robust method of graft manipulation, which can be used to engineer grafts for children with AML.

MicroRNA-519 enhances HL60 human acute myeloid leukemia cell line proliferation by reducing the expression level of RNA-binding protein human antigen R

Previous studies have demonstrated that microRNAs (miRs) are involved in cell apoptosis. However, the role of miR-519 in acute myeloid leukemia (AML) has yet to be elucidated. The present study identified the effects of miR‑519 on HL60 human acute myeloid leukemia cell growth and apoptosis. The expression levels of miR‑519 were examined in AML cells, as well as AML tissue samples. Furthermore, cell viability and apoptosis were examined in HL60 cells transfected with miR‑519 mimics, miR‑519 inhibitors or a negative control. In addition, the effects of human antigen R (HuR) on cell apoptosis were investigated using specific small interfering RNA targeting HuR. The results demonstrated that the expression levels of miR‑519 were significantly increased in the AML cells and the tissue samples, suggesting that miR‑519 may contribute to abnormal HL60 cell proliferation. Upregulation of miR‑519 expression decreased HL60 cell viability and induced cell apoptosis. Furthermore, knockdown of HuR reduced cell migration and enhanced cell apoptosis. The results of the present study indicate that miR‑519 may contribute to HL60 cell apoptosis by regulating the expression of HuR.

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

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

FLT3 mutational status is an independent risk factor for adverse outcomes after allogeneic transplantation in AML

Allogeneic HCT has been increasingly used in the setting of FLT3 mutated AML. However, its role in conferring durable relapse-free intervals remains in question. Herein, we sought to investigate FLT3 mutational status on transplant outcomes. We conducted a retrospective cohort study of 262 consecutive AML patients who underwent first-time allogeneic HCT (2008-2014), of whom 171 had undergone FLT3-ITD mutational testing. FLT3 mutated AML was associated with nearly twice the relapse risk (RR) compared with those without FLT3 mutation 3 years post-HCT (63% vs. 37%, P<0.001), and with a shorter median time to relapse (100 vs. 121 days). FLT3 mutational status remained significantly associated with this outcome after controlling for patient, disease, and transplant-related risk factors (P<0.05). Multivariate analysis showed a significant association of FLT3 mutation with increased 3-year RR (HR 3.63, 95% CI: 2.13, 6.19, P<0.001), and inferior disease-free survival (HR 2.05, 95% CI: 1.29, 3.27, P<0.01) and overall survival (HR 1.92, 95% CI: 1.14, 3.24, P<0.05). These data demonstrate high risk of early relapse after allogeneic HCT for FLT3 mutated AML that translates into adverse disease-free and overall survival outcomes. Additional targeted and coordinated interventions are needed to maintain durable remission after allogeneic HCT in this high-risk population.

Different aspects of stem cell procedures in children with poor responding AML: when is HSCT the best answer?

Acute myeloid leukemia in children is a heterogeneous disease with different morphological and cytogenetic features. New diagnostic tools and treatments, improved supportive care and the use of genomic tissue typing in selecting donors for hematopoietic stem cell transplantation (HSCT) adds to increased survival rates. Candidates to HSCT in first complete remission are patients with cytogenetic or molecular unfavorable prognostic markers, or blasts >15% after first induction. The use of minimal residual disease can also identify children benefiting from HSCT in first complete remission and the patients post HSCT with signs of relapse. The outcome and cure rate of acute myeloid leukemia, still remains poor and new diagnostic tools and treatments strategies need to be evaluated. In this management perspective, future management of novel minimal residual disease tools are discussed, conditioning therapies, as well as different transplantation procedures including haplo-transplantation and haplo-identical natural killer cell transplantation, but also altered graft-versus-host-disease treatments.

Acute myeloid leukemia in infants: biology and treatment

Children aged 0-2 years (i.e., infants) with acute myeloid leukemia (AML) are a peculiar subgroup of patients in the childhood AML scenario. They present with distinctive biological and clinical characteristics, including a high prevalence of prognostically unfavorable risk factors and an increased susceptibility to therapy-related toxicity. Remarkable improvements have been achieved over the last two decades in the treatment of these patients and their outcome is becoming superimposable to that of the older age groups. In this review, we will focus on peculiarities of this young subgroup of children with AML, describing their clinical presentation, the biology of disease, and factors influencing outcome. Treatment results and toxicity data reported by major collaborative groups are also summarized and compared.