Long-term results of children with acute myeloid leukemia: a report of three consecutive Phase III trials by the Children's Cancer Group: CCG 251, CCG 213 and CCG 2891

Intensive chemotherapy with dual induction and ALL-like consolidation for childhood acute myeloid leukemia: a respective report from multiple centers in China

Background

Pediatric acute myeloid leukemia (AML) has poor prognosis and high rate of relapse and mortality, and exploration of new treatment options is still critically needed.

Objectives

To summarize the outcome of our new treatment strategies for pediatric AML, which is characterized by dual induction and acute lymphoblastic leukemia (ALL) elements consolidation.

Design

Retrospective, single-arm study.

Methods

From July 2012 to December 2019, an intensive chemotherapy protocol was used for newly diagnosed children with AML, which contains dual induction, three courses of consolidations based on high-dose cytarabine, and two courses of consolidations composed of high-dose methotrexate, vincristine, asparaginase, and mercaptopurine (ALL-like elements). Blasts were monitored by bone marrow smears at intervals, and two lumbar punctures were performed during chemotherapy. We retrospectively analyzed the efficacy and safety of this study. The last follow-up was on 26 May 2023.

Results

A total of 70 pediatric AMLs were included. The median age at diagnosis was 6.7 (0.5-16.0) years. The median initial WBC count was 23.74 × 109/L, 11 of whom ⩾100 × 109/L. After dual induction, there were 62 cases of complete remission (CR), 5 cases of partial remission, and 3 cases of nonremission. The CR rate was 88.57%. The median follow-up time was 5.8 (0.2-9.4) years, the 5-year overall survival was 78.2% ± 5%, the event-free survival (EFS) was 71.2% ± 5.6%, and the cumulative recurrence rate was 27.75%. The 5-year EFS of patients with initial WBC < 100 × 109/L (n = 59) and ⩾100 × 109/L (n = 11) were 76.4% ± 5.7% and 45.5% ± 15% (p = 0.013), respectively. A total of 650 hospital infections occurred. The main causes of infection were respiratory tract infection (26.92%), septicemia (18.46%), stomatitis (11.85%), and skin and soft-tissue infection (10.46%).

Conclusion

This intensive treatment protocol with dual induction and ALL-like elements is effective and safe for childhood AML. Initial WBC ⩾ 100 × 109/L was the only independent risk factor in this cohort.

Trial registration

It is a retrospective study, and no registration on ClinicalTrials.gov.

Ligand-based targeting of c-kit using engineered γδ T cells as a strategy for treating acute myeloid leukemia

The application of immunotherapies such as chimeric antigen receptor (CAR) T therapy or bi-specific T cell engager (BiTE) therapy to manage myeloid malignancies has proven more challenging than for B-cell malignancies. This is attributed to a shortage of leukemia-specific cell-surface antigens that distinguish healthy from malignant myeloid populations, and the inability to manage myeloid depletion unlike B-cell aplasia. Therefore, the development of targeted therapeutics for myeloid malignancies, such as acute myeloid leukemia (AML), requires new approaches. Herein, we developed a ligand-based CAR and secreted bi-specific T cell engager (sBite) to target c-kit using its cognate ligand, stem cell factor (SCF). c-kit is highly expressed on AML blasts and correlates with resistance to chemotherapy and poor prognosis, making it an ideal candidate for which to develop targeted therapeutics. We utilize γδ T cells as a cytotoxic alternative to αβ T cells and a transient transfection system as both a safety precaution and switch to remove alloreactive modified cells that may hinder successful transplant. Additionally, the use of γδ T cells permits its use as an allogeneic, off-the-shelf therapeutic. To this end, we show mSCF CAR- and hSCF sBite-modified γδ T cells are proficient in killing c-kit+ AML cell lines and sca-1+ murine bone marrow cells in vitro. In vivo, hSCF sBite-modified γδ T cells moderately extend survival of NSG mice engrafted with disseminated AML, but therapeutic efficacy is limited by lack of γδ T-cell homing to murine bone marrow. Together, these data demonstrate preclinical efficacy and support further investigation of SCF-based γδ T-cell therapeutics for the treatment of myeloid malignancies.

Reduced-toxicity conditioning regimen with busulfan, fludarabine, rATG, and 400 cGy TBI in pediatric patients undergoing hematopoietic stem cell transplant for high-risk hematologic malignancies

Myeloablative conditioning regimens decrease the risk of relapse in pediatric patients undergoing allogeneic hematopoietic stem cell transplant (HCT) for hematologic malignancies, but cause significant toxicities PROCEDURE: This prospective study evaluated the use of a reduced-toxicity, myeloablative regimen with dose-adjusted busulfan, fludarabine, antithymocyte globulin and 400 cGy of total body irradiation in 40 patients < 21 years of age undergoing HCT for high-risk leukemias. Busulfan pharmacokinetics were measured to target 4000 μmol*min/day in the first 30 patients; this was increased to 5000 μmol*min/day in the subsequent 10 in efforts to further decrease relapse risk RESULTS: Overall survival at two- and five-years post-HCT was 67% and 51%, respectively. Relapse occurred in 11 patients (28%) at a median of seven months and was the leading cause of death. Transplant-related mortality was 8% and 13% at 100 days and one-year post-HCT, respectively. Trends toward improved survival were seen in patients transplanted for myeloid disease using bone marrow as stem cell source who achieved a busulfan AUC > 4000 μmol*min/day with two-year relapse-free survival approaching 80% CONCLUSIONS: This conditioning regimen is safe and effective in patients with high-risk leukemias, particularly myeloid disease. Larger studies are needed to compare its safety and efficacy to other myeloablative regimens in this population.

Adolescents and young adult acute myeloid leukemia outcomes at pediatric versus adult centers: A population-based study

BACKGROUND

Adolescents and young adult (AYA) acute myeloid leukemia (AML) outcomes remain poor. The impact of locus of care (LOC; adult vs pediatric) in this population is unknown.

PROCEDURE

The IMPACT cohort comprises detailed data for all Ontario, Canada, AYA aged 15-21 years diagnosed with AML between 1992 and 2012, linked to population-based health administrative data. We determined the impact of LOC on event-free survival (EFS) and overall survival (OS), treatment-related mortality (TRM), and relapse/progression.

RESULTS

Among 140 AYA, 51 (36.4%) received therapy at pediatric centers. The five-year EFS and OS for the whole cohort were 35.0% ± 4.0% and 53.6% ± 4.2%. Cumulative doses of anthracycline were higher among pediatric center AYA [median 355 mg/m² , interquartile range (IQR) 135-492 vs 202 mg/m² , IQR 140-364; P = 0.003]. In multivariable analyses, LOC was not predictive of either EFS [adult vs pediatric center hazard ratio (HR) 1.3, 95% confidence interval (CI) 0.8-2.2, P = 0.27] or OS (HR 1.0, CI 0.6-1.6, P = 0.97). However, patterns of treatment failure varied; higher two-year incidence of TRM in pediatric centers (23.5% ± 6.0% vs.10.1% ± 3.2%; P = 0.046) was balanced by lower five-year incidence of relapse/progression (33.3% ± 6.7% vs 56.2% ± 5.3%; P = 0.002).

CONCLUSIONS

AYA AML survival outcomes did not vary between pediatric and adult settings. Causes of treatment failure were different, with higher intensity pediatric protocols associated with higher TRM but lower relapse/progression. Careful risk stratification and enhanced supportive care may be of substantial benefit to AYA with AML by allocating maximal treatment intensity to patients who most benefit while minimizing the risk of TRM.

miR-21-5p promotes cell proliferation by targeting BCL11B in Thp-1 cells

Acute myeloid leukemia (AML) is a highly heterogeneous disease that remains untreatable. MicroRNAs (miRNAs or miRs) play important roles in the pathogenesis of leukemia. miR-21 is highly expressed in multiple types of human cancer and displays oncogenic activities; however, the clinical significance of miR-21 in AML remains unclear. In the present study, it was demonstrated that miR-21 levels were high in patients with AML and in AML cell lines. Further experiments demonstrated that overexpression of miR-21 in Thp-1 human monocytes derived from acute mononuclear leukemia peripheral blood promoted cell proliferation, while downregulation of miR-21-5p, a mature sequence derived from the 5' end of the miR-21 stem-loop precursor (another mature sequence, miR-21-3p, is derived form 3' end of miR-21), inhibited cell proliferation. Specifically, it was observed that overexpression of miR-21 could promote the transition of Thp-1 cells into the S and G2/M phases of the cell cycle, as shown by flow cytometry. Furthermore, inhibition of miR-21-5p arrested cells in the S and G2/M phases. Finally, BCL11B was determined to be a functional target of miR-21-5p by luciferase assays. Our study revealed functional and mechanistic associations between miR-21 and BCL11B in Thp-1 cells, which could serve to guide clinical treatment of 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.

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.

An evolutionary framework for treating pediatric sarcomas

Lessons from extinction can be used in trials designed to pursue a cure for cancer. When cancer cannot be cured, similar strategies may be unwise, and strategies that leverage the adaptations of cancer to therapy should be considered.

Genomic Variants of Cytarabine Sensitivity Associated with Treatment-Related Mortality in Pediatric AML: A Report from the Children's Oncology Group

PURPOSE

Cytarabine is an effective treatment for AML with associated toxicities including treatment related mortality (TRM). The purpose is to determine the clinical relevance of SNPs identified through the use of HapMap lymphoblastoid cell-based models, in predicting cytarabine response and toxicity in AML.

EXPERIMENTAL DESIGN

We tested clinical significance of SNPs associated with cytarabine sensitivity in children with AML treated on Children's Oncology Group regimens (CCG 2941/2961). Endpoints included overall survival (OS), event-free survival (EFS), and TRM. Patients who received bone marrow transplant were excluded. We tested 124 SNPs associated with cytarabine sensitivity in HapMap cell lines in 348 children to determine whether any associated with treatment outcomes. In addition, we tested five SNPs previously associated with TRM in children with AML in our independent dataset of 385 children.

RESULTS

Homozygous variant genotypes of rs2025501 and rs6661575 had increased in vitro cellular sensitivity to cytarabine and were associated with increased TRM. TRM was particularly increased in children with variant genotype randomized to high-dose cytarabine (rs2025501: P = 0.0024 and rs6661575 P = 0.0188). In analysis of previously reported SNPs, only the variant genotype rs17202778 C/C was significantly associated with TRM (P < 0.0001).

CONCLUSIONS

We report clinical importance of two SNPs not previously associated with cytarabine toxicity. Moreover, we confirm that SNP rs17202778 significantly impacts TRM in pediatric AML. Cytarabine sensitivity genotypes may predict TRM and could be used to stratify to standard versus high-dose cytarabine regimens, warranting further study in prospective AML trials.

Comparison of pediatric allogeneic transplant outcomes using myeloablative busulfan with cyclophosphamide or fludarabine

Busulfan combined with cyclophosphamide (BuCy) has long been considered a standard myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation (HCT), including both nonmalignant conditions and myeloid diseases. Substituting fludarabine for cyclophosphamide (BuFlu) to reduce toxicity without an increase in relapse has been increasingly performed in children, but without comparison with BuCy. We retrospectively analyzed 1781 children transplanted from 2008 to 2014 to compare the effectiveness of BuCy with BuFlu. Nonmalignant and malignant disease populations were analyzed separately. Overall mortality was comparable for children with nonmalignant conditions who received BuFlu or BuCy (relative risk [RR], 1.14, P = .52). Lower incidences of sinusoidal obstruction syndrome (P = .04), hemorrhagic cystitis (P = .04), and chronic graft-versus-host disease (P = .02) were observed after BuFlu, but the influence of the conditioning regimen could not be assessed by multivariate analysis because of the low frequency of these complications. Children transplanted for malignancies were more likely to receive BuFlu if they had higher hematopoietic cell transplantation-comorbidity index scores (P < .001) or their donor was unrelated and HLA-mismatched (P = .004). Nevertheless, there were no differences in transplant toxicities and comparable transplant-related mortality (RR, 1.2; P = .46), relapse (RR, 1.2; P = .15), and treatment failure (RR, 1.2; P = .12). BuFlu was associated with higher overall mortality (RR, 1.4; P = .008) related to inferior postrelapse survival (P = .001). Our findings demonstrated that outcomes after BuFlu are similar to those for BuCy for children, but for unclear reasons, those receiving BuFlu for malignancy may be at risk for shorter postrelapse survival.

Leukemic stem cell signatures identify novel therapeutics targeting acute myeloid leukemia

Therapy for acute myeloid leukemia (AML) involves intense cytotoxic treatment and yet approximately 70% of AML are refractory to initial therapy or eventually relapse. This is at least partially driven by the chemo-resistant nature of the leukemic stem cells (LSCs) that sustain the disease, and therefore novel anti-LSC therapies could decrease relapses and improve survival. We performed in silico analysis of highly prognostic human AML LSC gene expression signatures using existing datasets of drug–gene interactions to identify compounds predicted to target LSC gene programs. Filtering against compounds that would inhibit a hematopoietic stem cell (HSC) gene signature resulted in a list of 151 anti-LSC candidates. Using a novel in vitro LSC assay, we screened 84 candidate compounds at multiple doses and confirmed 14 drugs that effectively eliminate human AML LSCs. Three drug families presenting with multiple hits, namely antihistamines (astemizole and terfenadine), cardiac glycosides (strophanthidin, digoxin and ouabain) and glucocorticoids (budesonide, halcinonide and mometasone), were validated for their activity against human primary AML samples. Our study demonstrates the efficacy of combining computational analysis of stem cell gene expression signatures with in vitro screening to identify novel compounds that target the therapy-resistant LSC at the root of relapse in AML.

Presenting features and imaging in childhood acute myeloid leukemia with central nervous system involvement

Central nervous system (CNS) involvement in childhood acute myeloid leukemia (AML) can manifest as leukemic cells in the cerebrospinal fluid, a solid CNS tumor, or as neurological symptoms. We evaluated the presenting symptoms and neuroimaging findings in 33 of 34 children with AML and CNS involvement at diagnosis in the period 2000-2012 in Sweden, Finland, and Denmark. Imaging was performed in 22 patients, of whom 16 had CNS-related symptoms. Seven patients, including all but two with facial palsy, had mastoid cell opacification, considered an incidental finding. The frequent involvement of the mastoid bone with facial palsy warrants evaluation in larger series.

Administration of Dexrazoxane Improves Cardiac Indices in Children and Young Adults With Acute Myeloid Leukemia (AML) While Maintaining Survival Outcomes

Anthracycline-induced cardiotoxicity remains a significant contributor to late morbidity/mortality in children and young adults with acute myeloid leukemia (AML). The cardioprotectant dexrazoxane can be used as prophylaxis to diminish risk for cardiomyopathy but whether it affects risk of relapse in pediatric AML is unclear. Our institution adopted the use of dexrazoxane before anthracyclines administration for all oncology patients in 2011. We compared patients with AML (ages, 0 to 21 y) who received or did not receive dexrazoxane during the years 2008 to 2013. In total, 44 patients with AML (ages, 4.5 mo to 21.7 y) were included. We identified no statistical difference in 2-year event rate (62% vs. 50%, P=0.41) or 2-year overall survival (69% vs. 69%, P=0.53) between patients receiving (n=28) or not receiving (n=16) dexrazoxane. Ejection fraction (P=0.0262) and shortening fraction (P=0.0381) trended significantly higher in patients that received dexrazoxane compared with those that did not receive dexrazoxane. Utilization of the cardioprotectant dexrazoxane before anthracycline chemotherapy in pediatric patients with AML demonstrated no significant difference in either event rate or overall survival relative to institutional controls and seems to improve cardiac function indices. Further studies in this patient population are needed to confirm these findings.

High level of miR-196b at newly diagnosed pediatric acute myeloid leukemia predicts a poor outcome

Differential expression of microRNAs (miRNAs) has been implicated in leukemogenesis. We investigate the expression pattern of miR-196b. Using quantitative real-time PCR (qRT-PCR), we detected the expression of miR-196b and its correlated genes (SMC1A/MLH1) in initial pediatric AML. A significant association was observed between overexpression of miR-196b and inferior overall survival of pediatric AML (Log Rank P<0.0001). AML M4/5 subtype, high white blood cell (WBC) count at presentation, MLL rearrangement, or FLT3-ITD mutation at diagnosis and non-remission group after the first induction chemotherapy possessed higher miR-196b expression. Furthermore, a positive relationship was found between the expression of miR-196b and SMC1A/MLH1 (Spearman's r=0.37 and 0.44, P=0.001 and <0.0001, respectively). Taken together, these findings suggest that differentially high expression of miR-196b in diagnostic marrow samples of pediatric AML is associated with unfavorable outcome, and miR-196b potentially can be a novel biomarker for the diagnosis, prognosis and treatment in pediatric AML.

Health-related Quality of Life (HR-QOL) and Chronic Health Conditions in Survivors of Childhood Acute Myeloid Leukemia (AML) with Down Syndrome (DS): A Report From the Children's Oncology Group

Survival rates for children with Down syndrome (DS) and acute myeloid leukemia (AML) are high; however, little is known regarding the health-related quality of life (HR-QOL) of these survivors. Individuals who survived ≥5 years following diagnosis of childhood AML were invited to complete parent or patient-report surveys measuring HR-QOL and chronic health conditions. In total, 26 individuals with DS had a median age at diagnosis of 1.8 years (range, 0.77 to 10.9 y) and median age at interview of 15 years (range, 8.3 to 27.6 y). Participants with DS and AML were compared with AML survivors without DS whose caregiver completed a HR-QOL survey (CHQ-PF50). In total, 77% of survivors with DS reported ≥1 chronic health condition compared with 50% of AML survivors without DS (P=0.07). Mean physical and psychosocial QOL scores for children with DS and AML were statistically lower than the population mean, though not discrepant from AML survivors without DS. Although the overall prevalence of chronic health conditions in survivors with DS is higher than in survivors without DS, prior studies of children with DS have reported similarly high rates of chronic health conditions, suggesting that AML therapy may not substantially increase this risk.

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.

Accuracy of Adverse Event Ascertainment in Clinical Trials for Pediatric Acute Myeloid Leukemia

PURPOSE

Reporting of adverse events (AEs) in clinical trials is critical to understanding treatment safety, but data on AE accuracy are limited. This study sought to determine the accuracy of AE reporting for pediatric acute myeloid leukemia clinical trials and to test whether an external electronic data source can improve reporting.

METHODS

Reported AEs were evaluated on two trials, Children's Oncology Group AAML03P1 and AAML0531 arm B, with identical chemotherapy regimens but with different toxicity reporting requirements. Chart review for 12 AEs for patients enrolled in AAML0531 at 14 hospitals was the gold standard. The sensitivity and positive predictive values (PPV) of the AAML0531 AE report and AEs detected by review of Pediatric Health Information System (PHIS) billing and microbiology data were compared with chart data.

RESULTS

Select AE rates from AAML03P1 and AAML0531 arm B differed significantly and correlated with the targeted toxicities of each trial. Chart abstraction was performed on 204 patients (758 courses) on AAML0531. AE report sensitivity was < 50% for eight AEs, but PPV was > 75% for six AEs. AE reports for viridans group streptococcal bacteremia, a targeted toxicity on AAML0531, had a sensitivity of 78.3% and PPV of 98.1%. PHIS billing data had higher sensitivity (> 50% for nine AEs), but lower PPV (< 75% for 10 AEs). Viridans group streptococcal detection using PHIS microbiology data had high sensitivity (92.3%) and PPV (97.3%).

CONCLUSION

The current system of AE reporting for cooperative oncology group clinical trials in pediatric acute myeloid leukemia underestimates AE rates. The high sensitivity and PPV of PHIS microbiology data suggest that using external data sources may improve the accuracy of AE reporting.

Acute myeloid leukemia in children: Current status and future directions

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

A comparison of discharge strategies after chemotherapy completion in pediatric patients with acute myeloid leukemia: a report from the Children's Oncology Group

While most children receive acute myeloid leukemia (AML) chemotherapy as inpatients, there is variability in timing of discharge after chemotherapy completion. This study compared treatment-related morbidity, mortality and cumulative hospitalization in children with AML who were discharged after chemotherapy completion (early discharge) and those who remained hospitalized. Chart abstraction data for 153 early discharge-eligible patients enrolled on a Children's Oncology Group trial were compared by discharge strategy. Targeted toxicities included viridans group streptococcal (VGS) bacteremia, hypoxia and hypotension. Early discharge occurred in 11% of courses post-Induction I. Re-admission occurred in 80-100%, but median hospital stay was 7 days shorter. Patients discharged early had higher rates of VGS (adjusted risk ratio (aRR) = 1.67, 95% CI = 1.11-2.51), hypoxia (aRR = 1.92, 95% CI = 1.06-3.48) and hypotension (aRR = 4.36, 95% CI = 2.01-9.46), but there was no difference in mortality. As pressure increases to shorten hospitalizations, these results have important implications for determining discharge practices in pediatric AML.

Acute Myeloid Leukemia in Adolescents and Young Adults Treated in Pediatric and Adult Departments in the Nordic Countries

BACKGROUND

Studies on adolescents and young adults with acute lymphoblastic leukemia suggest better results when using pediatric protocols for adult patients, while corresponding data for acute myeloid leukemia (AML) are limited.

PROCEDURE

We investigated disease characteristics and outcome for de novo AML patients 10-30 years old treated in pediatric or adult departments. We included 166 patients 10-18 years of age with AML treated according to the pediatric NOPHO-protocols (1993-2009) compared with 253 patients aged 15-30 years treated in hematology departments (1996-2009) in the Nordic countries.

RESULTS

The incidence of AML was 4.9/million/year for the age group 10-14 years, 6.5 for 15-18 years, and 6.9 for 19-30 years. Acute promyelocytic leukemia (APL) was more frequent in adults and in females of all ages. Pediatric patients with APL had similar overall survival as pediatric patients without APL. Overall survival at 5 years was 60% (52-68%) for pediatric patients compared to 65% (58-70%) for adult patients. Cytogenetics and presenting white blood cell count were the only independent prognostic factors for overall survival. Age was not an independent prognostic factor.

CONCLUSIONS

No difference was found in outcome for AML patients age 10-30 years treated according to pediatric as compared to adult protocols.

Sex disparity in childhood and young adult acute myeloid leukemia (AML) survival: Evidence from US population data

Sex variation has been persistently investigated in studies concerning acute myeloid leukemia (AML) survival outcomes but has not been fully explored among pediatric and young adult AML patients. We detected sex difference in the survival of AML patients diagnosed at ages 0-24 years and explored distinct effects of sex across subgroups of age at diagnosis, race-ethnicity and AML subtypes utilizing the United States Surveillance Epidemiology and End Results (SEER) population based dataset of 4865 patients diagnosed with AML between 1973 and 2012. Kaplan-Meier survival function, propensity scores and stratified Cox proportional hazards regression were used for data analyses. After controlling for other prognostic factors, females showed a significant survival advantage over their male counterparts, adjusted hazard ratio (aHR, 95% confidence interval (CI): 1.09, 1.00-1.18). Compared to females, male patients had substantially increased risk of mortality in the following subgroups of: ages 20-24 years at diagnosis (aHR1.30), Caucasian (1.14), acute promyelocytic leukemia (APL) (1.35), acute erythroid leukemia (AEL) (1.39), AML with inv(16)(p13.1q22) (2.57), AML with minimum differentiation (1.47); and had substantially decreased aHR in AML t(9;11)(p22;q23) (0.57) and AML with maturation (0.82). Overall, females demonstrated increased survival over males and this disparity was considerably large in patients ages 20-24 years at diagnosis, Caucasians, and in AML subtypes of AML inv(16), APL and AEL. In contrast, males with AML t(9;11)(p22;q23), AML with maturation and age at diagnosis of 10-14 years showed survival benefit. Further investigations are needed to detect the biological processes influencing the mechanisms of these interactions.

Acute Myeloid Leukemia in Children: Experience from Tertiary Cancer Centre in India

There is paucity of data in pediatric Acute Myeloid Leukemia (AML) from developing countries. We analyzed the outcomes of 65 consecutive patients with pediatric AML treated at our centre from January-2008 to May-2013. The median event free survival (EFS) and overall survival (OS) were 12.6 and 14.6 months respectively. Patients with good-risk cytogenetics had a better EFS (p = 0.004) and OS (p = 0.01). Overall, these results are not comparable to that observed in other centres globally and leaves scope for further improvement. This includes implementing allogeneic bone marrow transplantation as a treatment for all children with high-risk AML.

Autocrine motility factor receptor promotes the proliferation of human acute monocytic leukemia THP-1 cells

The aberrant activation of autocrine motility factor receptor (AMFR) has been implicated in several types of human cancer. The present study aimed to elucidate the effect of AMFR on the regulation of proliferation in an acute monocytic leukemia cell line, THP‑1. THP‑1 cells were transfected with AMFR‑targeted small interfering (si)RNA and a plasmid encoding a truncated AMFR, AMFR‑C, (pcDNA3.1‑AMFR‑C). The mRNA and protein levels of AMFR and the downstream targets, rho‑associated, coiled‑coil containing protein kinase 2 (ROCK2), cyclin D1, and B‑cell lymphoma (Bcl)‑2, were measured using reverse transcription‑quantitatibe polymerase chain reaction and immunoblot analyses. The effects on cell cycle and apoptosis were investigated using flow cytometry. The present study successfully established the knockdown of AMFR and expression of AMFR‑C in the THP‑1 cells. Downregulation of AMFR induced cell cycle arrest at the G0/G1 phase, and increased apoptosis of the THP‑1 cells (all P<0.05). The AMFR siRNA increased the percentage of early apoptotic cells between 3.88±1.43 and 19.58±4.29% (P<0.05). The expression levels of ROCK2, cyclin D1 and Bcl‑2 were reduced by the downregulation of AMFR and enhanced by overexpression of AMFR‑C. In conclusion, AMFR appears to be crucial for the proliferation of the THP‑1 acute monocytic leukemia cell line. Therefore, AMFR may represent a potential target for the treatment of acute monocytic leukemia.

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.

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.

Global characteristics of childhood acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) comprises approximately 5-10% of childhood acute myeloid leukemia (AML) cases in the US. While variation in this percentage among other populations was noted previously, global patterns of childhood APL have not been thoroughly characterized. In this comprehensive review of childhood APL, we examined its geographic pattern and the potential contribution of environmental factors to observed variation. In 142 studies (spanning >60 countries) identified, variation was apparent-de novo APL represented from 2% (Switzerland) to >50% (Nicaragua) of childhood AML in different geographic regions. Because a limited number of previous studies addressed specific environmental exposures that potentially underlie childhood APL development, we gathered 28 childhood cases of therapy-related APL, which exemplified associations between prior exposures to chemotherapeutic drugs/radiation and APL diagnosis. Future population-based studies examining childhood APL patterns and the potential association with specific environmental exposures and other risk factors are needed.

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.

Beyond CD19: Opportunities for Future Development of Targeted Immunotherapy in Pediatric Relapsed-Refractory Acute Leukemia

Chimeric antigen receptor (CAR) T cell therapy has been used as a targeted approach in cancer therapy. Relapsed and refractory acute leukemia in pediatrics has been difficult to treat with conventional therapy due to dose-limiting toxicities. With the recent success of CD 19 CAR in pediatric patients with B cell acute lymphoblastic leukemia (ALL), this mode of therapy has become a very attractive option for these patients with high-risk disease. In this review, we will discuss current treatment paradigms of pediatric acute leukemia and potential therapeutic targets for additional high-risk populations, including T cell ALL, AML, and infant ALL.

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

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

A critical review of which children with acute myeloid leukaemia need stem cell procedures

The last decades have seen parallel improvements in chemotherapy-based and haematopoietic stem cell transplantation (HSCT) regimens for acute myeloid leukaemia (AML) in children. There has been no consensus on indication for HSCT. Reserving HSCT for high-risk and relapsed patients spare many patients from the long-term toxicity of this treatment. The results of matched unrelated donor HSCT equal family donor transplantation and the presence of a matched sibling should no longer be a transplant indication. Minimal residual disease measured by flow cytometry may identify poor responders benefitting from HSCT in first complete remission (CR1) and those with a favourable response to induction therapy who do not need HSCT even with adverse cytogenetic aberrations. FLT3-internal tandem duplication without NPM1 mutation has a very high relapse rate despite favourable response and HSCT is indicated in CR1 in these cases. Finding the optimal indications for HSCT is a delicate balance between risk of relapse and late effects.

Expression of CD90, CD96, CD117, and CD123 on different hematopoietic cell populations from pediatric patients with acute myeloid leukemia

BACKGROUND AND AIMS

In trying to contribute to our knowledge on the biology of hematopoietic stem cells (HSC) and hematopoietic progenitor cells (HPC) from pediatric acute myeloid leukemia (AML), in the present study we analyzed the expression of four cell surface antigens relevant to human hematopoiesis-CD90, CD96, CD117, and CD123-in bone marrow from pediatric AML patients and normal control subjects.

METHODS

CD34(+) CD38(-) cells (enriched for HSC) and CD34(+) CD38(+) cells (enriched for HPC) were resolved on the basis of CD34 and CD38 expression. Concomitantly, expression of CD90 and CD96 or CD117 and CD123 was assessed by multicolor flow cytometry in each cell population.

RESULTS

CD90 and CD117 were expressed in a low proportion of CD34(+) CD38(-) and CD34(+) CD38(+) cells and no significant differences were observed between normal marrow and AML at diagnosis. In contrast, CD96(+) cells and CD123(+) cells were found at significantly higher levels in both cell populations from AML at diagnosis, as compared to normal marrow. Levels of both cell surface markers after treatment remained higher than in normal marrow.

DISCUSSION

These results show an increased frequency of CD96(+) and CD123(+) cells within the CD34(+) cell population from pediatric AML; this is consistent with the findings reported previously for adult AML. Our study supports the notion that expression of such antigens should be explored for their use as markers for diagnosis and prognosis.

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

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

Health conditions and quality of life in survivors of childhood acute myeloid leukemia comparing post remission chemotherapy to BMT: a report from the children's oncology group

BACKGROUND

Therapy for childhood acute myeloid leukemia (AML) has historically included chemotherapy with or without autologous bone marrow transplant (autoBMT) or allogeneic hematopoietic stem cell transplantation (alloBMT). We sought to compare health-related quality-of-life (HRQOL) outcomes between these treatment groups.

PROCEDURE

Five-year survivors of AML diagnosed before age 21 and enrolled and treated from 1979 to 1995 on one of 4 national protocols were interviewed. These survivors or proxy caregivers completed a health questionnaire and an HRQOL measure.

RESULTS

Of 180 survivors, 100 were treated with chemotherapy only, 26 with chemotherapy followed by autoBMT, and 54 with chemotherapy followed by alloBMT. Median age at interview was 20 years (range 8-39). Twenty-one percent reported a severe or life-threatening chronic health condition (chemotherapy-only 16% vs. autoBMT 21% vs. alloBMT 33%; P = 0.02 for chemotherapy-only vs. alloBMT). Nearly all (95%) reported excellent, very good or good health. Reports of cancer-related pain and anxiety did not vary between groups. HRQOL scores among 136 participants ≥14 years of age were similar among groups and to the normative population, though alloBMT survivors had a lower physical mean summary score (49.1 alloBMT vs. 52.2 chemotherapy-only; P = 0.03). Multivariate analyses showed the presence of severe chronic health conditions to be a strong predictor of physical but not mental mean summary scores.

CONCLUSIONS

Overall HRQOL scores were similar among treatment groups, although survivors reporting more health conditions or cancer-related pain had diminished HRQOL. Attention to chronic health conditions and management of cancer-related pain may improve QOL.

Appropriate dose reduction in induction therapy is essential for the treatment of infants with acute myeloid leukemia: a report from the Japanese Pediatric Leukemia/Lymphoma Study Group

Infants (<1 year old) with acute myeloid leukemia (AML) are particularly vulnerable to intensive cytotoxic therapy. Indeed, the mortality rate was high among infants enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study, which prompted us to temporarily suspend patient enrollment and amend the protocol. Forty-five infants with AML were enrolled. For patients aged <2 years, drug doses were adjusted for body weight. Following the protocol amendments, doses for infants were reduced by a further 33 % in the initial induction course. Six infants died during the induction phase (including five early deaths), mainly due to pulmonary complications. The 3-year probability of overall survival (pOS) in all 45 infants [55.9 %, 95 % confidence interval (CI) 37.9-70.6 %] was significantly lower than that of patients aged 1 to <2 years (77.0 %, 95 % CI 62.7-86.3 %) and those aged ≥2 years (74.7 %, 95 % CI 69.2-79.4 %) (P = 0.037), mainly due to the higher non-relapse mortality rate in infants. No early deaths occurred after the protocol amendments, and the 3-year pOS of the 17 infants enrolled thereafter was 76.4 % (95 % CI 48.8-90.4 %). In conclusion, appropriate dose reduction is essential to avoid early deaths when treating infants with AML.

Dexrazoxane use in pediatric patients with acute lymphoblastic or myeloid leukemia from 1999 and 2009: analysis of a national cohort of patients in the Pediatric Health Information Systems database

BACKGROUND

Acute lymphoblastic (ALL) and myeloid leukemia (AML) account for approximately 26% of pediatric cancers. Anthracyclines are widely used to treat these leukemias, but dosing is limited by cardiotoxicity. Data support the efficacy of dexrazoxane as a cardioprotectant in children; however, dexrazoxane use in children is not universally accepted due to concerns about toxicity, impact on the antitumor effect of anthracyclines, and risk of secondary malignant neoplasms (SMN).

PROCEDURE

We conducted a retrospective cohort study to describe patterns of dexrazoxane use in pediatric patients with ALL or AML using the Pediatric Health Information Systems (PHIS) database. Patients identified as having de novo ALL and AML at these PHIS hospitals were included.

RESULTS

Of 8,733 patients with ALL and 2,556 with AML, 207 (2.4%) and 52 (2.0%) received dexrazoxane, respectively. Dexrazoxane use was greater in older children with ALL and AML and in black patients and males with ALL. Dexrazoxane use varied across time and by region in ALL, but not in AML. Prescribing practices differed across institutions and most patients received the first dose early or late after the start of leukemia treatment.

CONCLUSIONS

Dexrazoxane administration is limited in patients with ALL and AML and prescribing practices vary across the country. Further work is necessary to understand how dexrazoxane is used in patients at highest risk of developing cardiotoxicity and to define its true effect on the development of SMNs.

Very late isolated CNS relapse of acute myeloid leukemia

Isolated central nervous system (CNS) relapse in acute myeloid leukemia (AML) rarely occurs later than 2 years after remission. We present a child diagnosed with AML (FAB M5) without CNS involvement at diagnosis who was treated with chemotherapy and consolidated with autologous hematopoietic stem cell transplantation. He was in complete remission for >6 years until he had an isolated CNS relapse. He was treated with only intrathecal chemotherapy and achieved a second complete remission, but relapsed in the bone marrow 5 months after the CNS relapse. Treatment of late isolated CNS relapse of AML is discussed.

Differentially expressed miRNAs in cytogenetic and molecular subtypes of pediatric acute myeloid leukemia

BACKGROUND

miRNAs regulate gene expression, and thus play an important role in critical cellular processes. Aberrant miRNA expression patterns have been found in various types of cancer. So far, information about the expression of miRNAs in pediatric acute myeloid leukemia is limited.

PROCEDURE

We studied expression of miR-29a, -155, -196a, and -196b by stem-loop based RT-qPCR in 82 pediatric acute myeloid leukemia patients selected to represent relevant cytogenetic and molecular subgroups.

RESULTS

High miR-196a and -b expression was observed in patients carrying MLL gene rearrangements (P < 0.001), NPM1 mutations (P < 0.001), or FLT3-ITD in a cytogenetically normal background (P ≤ 0.02), compared to all other patients. In contrast, CEBPA mutated cases had a low expression of miR-196a and -b (P ≤ 0.001). Expression of miR-196a and -b was correlated with expression of neighboring HOXA and HOXB genes (Spearman's r = 0.46-0.82, P < 0.01). Expression of miR-155 was not related to cytogenetic features but high expression of miR-155 was observed in FLT3-ITD (P = 0.001) and NPM1-mutated cases (P = 0.04). Lower miR-29a expression was mainly observed in MLL-rearranged pediatric acute myeloid leukemia, specifically in cases carrying t(10;11) (P < 0.001).

CONCLUSIONS

We show aberrant expression of specific miRNAs in clinically relevant cytogenetic and molecular subgroups of pediatric acute myeloid leukemia, suggesting a role for these miRNAs in the underlying biology in these specific subgroups.

A single-center cytogenetic study of 629 Chinese patients with de novo acute myeloid leukemia--evidence of major ethnic differences and a high prevalence of acute promyelocytic leukemia in Chinese patients

Cytogenetic information is important in the diagnosis, classification, and prognostication of acute myeloid leukemia (AML). Data obtained from multicenter treatment trials are well published. In this study, we contribute cytogenetic data from a large series of 629 Chinese patients with de novo AML that were karyotyped in a single laboratory. A higher prevalence of acute promyelocytic leukemia was observed when compared with non-Chinese series. The difference was most prominent in the younger age group. Abnormalities at chromosomal region 11q23 and inv(16) seemed uncommon. These ethnic differences may indicate underlying genetic susceptibility to AML development and/or environmental differences. More comprehensive data on AML in the elder population are needed to assess the role of cytogenetics in predicting prognosis and guiding treatment in this large subgroup of patients.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effect of RNAi-induced down regulation of nuclear factor kappa-B p65 on acute monocytic leukemia THP-1 cells in vitro and vivo

NF-κB p65 is found constitutively active in acute monocytic leukemia, and has been considered an important factor for poor prognosis. Therefore, develop specifically target p65 inhibitors will be substantial interest. Until now, although several p65 inhibitors are currently in preclinical and clinical development, none of them are targeting. In this study, siRNA targeting p65 was introduced into the acute monocytic leukemia cell line THP-1 and THP-1 xenograft tumors in nude mice, and then, we measured p65 mRNA and protein levels by real-time RT-PCR and Western blotting, and levels of related protein cyclin D1, Bc1-2, and SMRT by Western blotting. We also investigated the cell cycle and apoptosis via FCM, and cell proliferation by Cell Counting Kit-8 assay. We found that p65 siRNA could effectively reduce the p65 mRNA and protein expression, arrest cells in G0/G1 phase, inhibit the proliferation and increase the apoptosis of THP-1 cells, and intratumoral injection of p65 siRNA could suppress tumor growth in nude mice. We also found that when down regulation of p65, the expression of cyclin D1 and Bc1-2 decreased, and the expression of SMRT increased in vitro and vivo. All these findings suggest that NF-κB p65 maybe an attractive candidate for the therapeutic targeting of acute monocytic leukemia.

AAML03P1, a pilot study of the safety of gemtuzumab ozogamicin in combination with chemotherapy for newly diagnosed childhood acute myeloid leukemia: a report from the Children's Oncology Group

BACKGROUND

The development of antigen-targeted therapies may provide additional options to improve outcomes in children with acute myeloid leukemia (AML). The Children's Oncology Group AAML03P1 trial sought to determine the safety of adding 2 doses of gemtuzumab ozogamicin, a humanized anti-CD33 antibody-targeted agent, to intensive chemotherapy during remission induction and postremission intensification for children with de novo AML.

METHODS

AAML03P1 enrolled 350 children with previously untreated AML. Patients with a matched family donor received 3 courses of chemotherapy followed by hematopoietic stem cell transplantation; those without a matched family donor received 5 courses of chemotherapy. Gemtuzumab ozogamicin 3 mg/m(2)/dose was administered on Day 6 of Course 1 and Day 7 of Course 4.

RESULTS

Toxicities observed in all courses of therapy were typical of AML chemotherapy regimens, with infection being most common. Patients achieved a complete remission rate of 83% after 1 course and 87% after 2 courses. The mortality rate was 1.5% after the first gemtuzumab ozogamicin-containing induction course and 2.6% after 2 induction courses. The 3-year event-free survival and overall survival rates were 53 ± 6% and 66 ± 5%, respectively.

CONCLUSIONS

This trial determined that it is safe and feasible to include gemtuzumab ozogamicin in combination with intensive chemotherapy. The survival rates compare favorably with the recently published results of clinical trials worldwide.

Prognostic significance of additional cytogenetic aberrations in 733 de novo pediatric 11q23/MLL-rearranged AML patients: results of an international study

We previously demonstrated that outcome of pediatric 11q23/MLL-rearranged AML depends on the translocation partner (TP). In this multicenter international study on 733 children with 11q23/MLL-rearranged AML, we further analyzed which additional cytogenetic aberrations (ACA) had prognostic significance. ACAs occurred in 344 (47%) of 733 and were associated with unfavorable outcome (5-year overall survival [OS] 47% vs 62%, P < .001). Trisomy 8, the most frequent specific ACA (n = 130/344, 38%), independently predicted favorable outcome within the ACAs group (OS 61% vs 39%, P = .003; Cox model for OS hazard ratio (HR) 0.54, P = .03), on the basis of reduced relapse rate (26% vs 49%, P < .001). Trisomy 19 (n = 37/344, 11%) independently predicted poor prognosis in ACAs cases, which was partly caused by refractory disease (remission rate 74% vs 89%, P = .04; OS 24% vs 50%, P < .001; HR 1.77, P = .01). Structural ACAs had independent adverse prognostic value for event-free survival (HR 1.36, P = .01). Complex karyotype, defined as ≥ 3 abnormalities, was present in 26% (n = 192/733) and showed worse outcome than those without complex karyotype (OS 45% vs 59%, P = .003) in univariate analysis only. In conclusion, like TP, specific ACAs have independent prognostic significance in pediatric 11q23/MLL-rearranged AML, and the mechanism underlying these prognostic differences should be studied.

Acute myeloid leukemia with the t(8;21) translocation: clinical consequences and biological implications

The t(8;21) abnormality occurs in a minority of acute myeloid leukemia (AML) patients. The translocation results in an in-frame fusion of two genes, resulting in a fusion protein of one N-terminal domain from the AML1 gene and four C-terminal domains from the ETO gene. This protein has multiple effects on the regulation of the proliferation, the differentiation, and the viability of leukemic cells. The translocation can be detected as the only genetic abnormality or as part of more complex abnormalities. If t(8;21) is detected in a patient with bone marrow pathology, the diagnosis AML can be made based on this abnormality alone. t(8;21) is usually associated with a good prognosis. Whether the detection of the fusion gene can be used for evaluation of minimal residual disease and risk of leukemia relapse remains to be clarified. To conclude, detection of t(8;21) is essential for optimal handling of these patients as it has both diagnostic, prognostic, and therapeutic implications.