Decreased relapsed rate and treatment-related mortality contribute to improved outcomes for pediatric acute myeloid leukemia in successive clinical trials

Utilization of supportive care medications and opportunities for pre-emptive pharmacogenomic testing in pediatric and young adults with leukemia

This study aimed to evaluate the utilization of drugs with pharmacogenomic guidelines (PGx-drugs) for personalized dosing in pediatric leukemia. A retrospective observational study of pediatric leukemia patients admitted between 2009-2019 at a single-center academic children's hospital was conducted to determine PGx-drug exposure within 3 years of diagnosis. Along with baseline demographic and clinical characteristics of these patients, data regarding dates of diagnosis, relapse, death were collected. During the study period, inclusion criteria were met by 714 patients. The most frequently given medications were ondansetron (96.1%), morphine (92.2%), and allopurinol (85.3%) during the study period. In this cohort, 82% of patients received five or more PGx-drugs. Patients diagnosed with acute myeloid leukemia and leukemia unspecified were prescribed more PGx-drugs than other types of leukemia. There was a significant relationship between age at diagnosis and the number of PGx-drugs prescribed. Adolescents and adults both received a median of 10 PGx-drugs, children received a median of 6 PGx-drugs, and infants received a median of 7 PGx-drugs (p < 0.001). Patients with recurrent leukemia had significantly more PGx-drugs prescribed compared to those without recurrent disease, 10 drugs and 6 drugs, respectively (p < 0.001). Patients diagnosed with childhood leukemia are high utilizers of PGx-drugs. There is a vital need to understand how PGx testing may be utilized to optimize treatment and enhance quality of life. Preemptive PGx testing is a tool that aids in optimization of drug therapy and decreases the need for later treatment modifications. This can result in financial savings from decreased health-care encounters.

Mitoxantrone Versus Liposomal Daunorubicin in Induction of Pediatric AML With Risk Stratification Based on Flow Cytometry Measurement of Residual Disease

PURPOSE

Measurable residual disease (MRD) by using flow cytometry after induction therapy is strongly prognostic in pediatric AML, and hematopoietic stem-cell transplant (hSCT) may counteract a poor response. We designed a phase III study with intensified response-guided induction and MRD-based risk stratification and treated poor induction response with hSCT. The efficacy of liposomal daunorubicin (DNX) in induction was compared with mitoxantrone.

METHODS

The study planned to randomly assign 300 patients, but the production of DNX ceased in 2017. One hundred ninety-four patients were randomly assigned to mitoxantrone or experimental DNX in induction 1. Ninety-three non-randomly assigned patients served as an observation cohort. Primary end point was fraction of patients with MRD <0.1% on day 22 after induction 1. Patients with MRD ≥15% after induction 1 or ≥0.1% after induction 2 or FLT3-ITD with NPM1 wildtype were stratified to high-risk therapy, including hSCT.

RESULTS

Outcome for all 287 children was good with 5-year event-free survival (EFS5y) 66.7% (CI, 61.4 to 72.4) and 5-year overall survival (OS5y) 79.6% (CI, 75.0 to 84.4). Overall, 75% were stratified to standard-risk and 19% to high-risk. There was no difference in the proportion of patients with MRD <0.1% on day 22 after induction 1 (34% mitoxantrone, etoposide, araC [MEC], 30% DNX, P = .65), but the proportion increased to 61% for MEC versus 47% for DNX (P = .061) at the last evaluation before induction 2. EFS5y was significantly lower, 56.6% (CI, 46.7 to 66.5) versus 71.9% (CI, 63.0 to 80.9), and cumulative incidence of relapse (CIR) was higher, 35.1% (CI, 25.7 to 44.7) versus 18.8% (CI, 11.6 to 27.2) for DNX. The inferior outcome for DNX was only in standard-risk patients with EFS5y 55.3% (CI, 45.1 to 67.7) versus 79.9% (CI, 71.1 to 89.9), CIR 39.5% (CI, 28.4 to 50.3) versus 18.7% (CI, 10.5 to 28.7), and OS5y 76.2% (CI, 67.2 to 86.4) versus 88.6% (CI, 81.4 to 96.3). As-treated analyses, including the observation cohort, supported these results. For all high-risk patients, 85% received hSCT, and EFS5y was 77.7 (CI, 67.3 to 89.7) and OS5y was 83.0 (CI, 73.5 to 93.8).

CONCLUSION

The intensification of induction therapy with risk stratification on the basis of response to induction and hSCT for high-risk patients led to improved outcomes. Mitoxantrone had a superior anti-leukemic effect than liposomal daunorubicin.

Structural variants involving MLLT10 fusion are associated with adverse outcomes in pediatric acute myeloid leukemia

ABSTRACT

MLLT10 gene rearrangements with KMT2A occur in pediatric acute myeloid leukemia (AML) and confer poor prognosis, but the prognostic impact of MLLT10 in partnership with other genes is unknown. We conducted a retrospective study with 2080 children and young adults with AML registered on the Children's Oncology Group AAML0531 (NCT00372593) and AAML1031 trials (NCT01371981). Transcriptome profiling and/or karyotyping were performed to identify leukemia-associated fusions associated with prognosis. Collectively, 127 patients (6.1%) were identified with MLLT10 fusions: 104 (81.9%) with KMT2A::MLLT10, 13 (10.2%) with PICALM::MLLT10, and 10 (7.9%) X::MLLT10: (2 each of DDX3X and TEC), with 6 partners (DDX3Y, CEP164, SCN2B, TREH, NAP1L1, and XPO1) observed in single patients. Patients with MLLT10 (n = 127) demonstrated adverse outcomes, with 5-year event-free survival (EFS) of 18.6% vs 49% in patients without MLLT10 (n = 1953, P < .001), inferior 5-year overall survival (OS) of 38.2% vs 65.7% (P ≤ .001), and a higher relapse risk of 76% vs 38.6% (P < .001). Patients with KMT2A::MLLT10 had an EFS from study entry of 19.5% vs 12.7% (P = .628), and an OS from study entry of 40.4% vs 27.6% (P = .361) in those with other MLLT10 fusion partners. Patients with PICALM::MLLT10 had an EFS of 9.2% vs 20% in other MLLT10- without PICALM (X::MLLT10; P = .788). Patients with PICALM::MLLT10 and X::MLLT10 fusions exhibit a DNA hypermethylation signature resembling NUP98::NSD1 fusions, whereas patients with KMT2A::MLLT10 bear aberrations primarily affecting distal regulatory elements. Regardless of the fusion partner, patients with AML harboring MLLT10 fusions exhibit very high-risk features and should be prioritized for alternative therapeutic interventions.

A longitudinal single-cell atlas of treatment response in pediatric AML

Pediatric acute myeloid leukemia (pAML) is characterized by heterogeneous cellular composition, driver alterations and prognosis. Characterization of this heterogeneity and how it affects treatment response remains understudied in pediatric patients. We used single-cell RNA sequencing and single-cell ATAC sequencing to profile 28 patients representing different pAML subtypes at diagnosis, remission and relapse. At diagnosis, cellular composition differed between genetic subgroups. Upon relapse, cellular hierarchies transitioned toward a more primitive state regardless of subtype. Primitive cells in the relapsed tumor were distinct compared to cells at diagnosis, with under-representation of myeloid transcriptional programs and over-representation of other lineage programs. In some patients, this was accompanied by the appearance of a B-lymphoid-like hierarchy. Our data thus reveal the emergence of apparent subtype-specific plasticity upon treatment and inform on potentially targetable processes.

Prediction of attributable mortality in pediatric patients with cancer admitted to the intensive care unit for suspected infection: A comprehensive evaluation of risk scores

OBJECTIVE

To evaluate the performance of existing sepsis scores for prediction of adverse outcomes in children with cancer admitted to the ICU with suspected sepsis.

DESIGN

Retrospective chart review using data available at 1, 6, 12, and 24 h after ICU admission to calculate the Pediatric Risk of Mortality 3 (PRISM-3), Pediatric Sequential Organ Failure Assessment (pSOFA), Paediatric Logistic Organ Dysfunction 2 (PELOD-2), and Quick Pediatric Sequential Organ Failure Assessment (qSOFA) scores. Area under the receiver operator characteristic curve (AUROC) was used to evaluate performance for prediction of attributable mortality. Sensitivity analyses included recalculation of scores using worst preceding values for each variable, excluding hematologic parameters, and prediction of alternative outcomes.

SETTING

St. Jude Children's Research Hospital, a pediatric comprehensive cancer center in the USA.

PATIENTS

Pediatric patients (<25 years of age) receiving conventional therapy for cancer admitted to the ICU with suspected sepsis between 2013 and 2019.

RESULTS

Of 207 included episodes of suspected sepsis, attributable mortality was 16 (7.7%) and all evaluated sepsis scores performed poorly (maximal AUROC of 0.73 for qSOFA at 1 and 24 h). Sensitivity analyses did not identify an alternative approach that significantly improved prediction.

CONCLUSIONS

Currently available sepsis scores perform poorly for prediction of attributable mortality in children with cancer who present to ICU with suspected sepsis. More research is needed to identify reliable predictors of adverse outcomes in this population.

Therapeutic targeting in pediatric acute myeloid leukemia with aberrant HOX/MEIS1 expression

Despite advances in the clinical management of childhood acute myeloid leukemia (AML) during the last decades, outcome remains fatal in approximately one third of patients. Primary chemoresistance, relapse and acute and long-term toxicities to conventional myelosuppressive therapies still constitute significant challenges and emphasize the unmet need for effective targeted therapies. Years of scientific efforts have translated into extensive insights on the heterogeneous spectrum of genetics and oncogenic signaling pathways of AML and identified a subset of patients characterized by upregulation of HOXA and HOXB homeobox genes and myeloid ecotropic virus insertion site 1 (MEIS1). Aberrant HOXA/MEIS1 expression is associated with genotypes such as rearrangements in Histone-lysine N-methyltransferase 2A (KMT2A-r), nucleoporin 98 (NUP98-r) and mutated nucleophosmin (NPM1c) that are found in approximately one third of children with AML. AML with upregulated HOXA/MEIS1 shares a number of molecular vulnerabilities amenable to recently developed molecules targeting the assembly of protein complexes or transcriptional regulators. The interaction between the nuclear scaffold protein menin and KMT2A has gained particular interest and constitutes a molecular dependency for maintenance of the HOXA/MEIS1 transcription program. Menin inhibitors disrupt the menin-KMT2A complex in preclinical models of KMT2A-r, NUP98-r and NPM1c acute leukemias and its occupancy at target genes leading to leukemic cell differentiation and apoptosis. Early-phase clinical trials are either ongoing or in development and preliminary data suggests tolerable toxicities and encouraging efficacy of menin inhibitors in adults with relapsed or refractory KMT2A-r and NPM1c AML. The Pediatric Acute Leukemia/European Pediatric Acute Leukemia (PedAL/EUPAL) project is focused to advance and coordinate informative clinical trials with new agents and constitute an ideal framework for testing of menin inhibitors in pediatric study populations. Menin inhibitors in combination with standard chemotherapy or other targeting agents may enhance anti-leukemic effects and constitute rational treatment strategies for select genotypes of childhood AML, and provide enhanced safety to avoid differentiation syndrome. In this review, we discuss the pathophysiological mechanisms in KMT2A-r, NUP98-r and NPM1c AML, emerging molecules targeting the HOXA/MEIS1 transcription program with menin inhibitors as the most prominent examples and future therapeutic implications of these agents in childhood AML.

Treatment outcomes of pediatric acute myeloid leukemia in Western Kenya before and after the implementation of the SIOP PODC treatment guideline

PURPOSE

The Pediatric Oncology in Developing Countries (PODC) committee of the International Society of Pediatric Oncology (SIOP) published a pediatric acute myeloid leukemia (AML)-specific adapted treatment guideline for low- and middle-income countries. We evaluated the outcomes of children with AML at a large Kenyan academic hospital before (period 1) and after (period 2) implementing this guideline.

PATIENTS AND METHODS

Records of children (≤17 years) newly diagnosed with AML between 2010 and 2021 were retrospectively studied. In period 1, induction therapy comprised two courses with doxorubicin and cytarabine, and consolidation comprised two courses with etoposide and cytarabine. In period 2, a prephase with intravenous low-dose etoposide was administered prior to induction therapy, induction course I was intensified, and consolidation was adapted to two high-dose cytarabine courses. Probabilities of event-free survival (pEFS) and overall survival (pOS) were estimated using the Kaplan-Meier method.

RESULTS

One-hundred twenty-two children with AML were included - 83 in period 1 and 39 in period 2. Overall, 95 patients received chemotherapy. The abandonment rate was 19% (16/83) in period 1 and 3% (1/39) in period 2. The early death, treatment-related mortality, complete remission, and relapse rates in periods 1 and 2 were 46% (29/63) versus 44% (14/32), 36% (12/33) versus 47% (8/17), 33% (21/63) versus 38% (12/32), and 57% (12/21) versus 17% (2/12), respectively. The 2-year pEFS and pOS in periods 1 and 2 were 5% versus 15% (p = .53), and 8% versus 16% (p = .93), respectively.

CONCLUSION

The implementation of the SIOP PODC guideline did not result in improved outcomes of Kenyan children with AML. Survival of these children remains dismal, mainly attributable to early mortality.

Update on Small Molecule Targeted Therapies for Acute Myeloid Leukemia

OPINION STATEMENT

The search for effective therapies for the highly heterogenous disease acute myeloid leukemia (AML) has remained elusive. While cytotoxic therapies can induce complete remission and even, at times, long-term survival, this approach is associated with significant toxic effects to visceral organs and worsening of immune dysfunction and marrow suppression leading to death. Sophisticated molecular studies have revealed defects within the AML cell that can be exploited by utilizing small molecule agents to target these defects, often dubbed "target therapy." Several medications have already established new standards of care for many patients with AML, including FDA-approved agents that inhibitor IDH1, IDH2, FLT3, and BCL-2. Emerging small molecules hold additional to add to the armamentarium of AML treatment options including MCL-1 inhibitors, TP53 inhibitors, menin inhibitors, and E-selectin antagonists. Moreover, the increasing options also mean that future combinations of these agents need to be explored, including with cytotoxic drugs and other newer emerging strategies such as immunotherapies for AML. Recent investigations continue to show that overcoming many of the challenges of treating AML finally is on the horizon.

Reconstructing Clonal Evolution-A Systematic Evaluation of Current Bioinformatics Approaches

The accurate reconstruction of clonal evolution, including the identification of newly developing, highly aggressive subclones, is essential for the application of precision medicine in cancer treatment. Reconstruction, aiming for correct variant clustering and clonal evolution tree reconstruction, is commonly performed by tedious manual work. While there is a plethora of tools to automatically generate reconstruction, their reliability, especially reasons for unreliability, are not systematically assessed. We developed clevRsim-an approach to simulate clonal evolution data, including single-nucleotide variants as well as (overlapping) copy number variants. From this, we generated 88 data sets and performed a systematic evaluation of the tools for the reconstruction of clonal evolution. The results indicate a major negative influence of a high number of clones on both clustering and tree reconstruction. Low coverage as well as an extreme number of time points usually leads to poor clustering results. An underlying branched independent evolution hampers correct tree reconstruction. A further major decline in performance could be observed for large deletions and duplications overlapping single-nucleotide variants. In summary, to explore the full potential of reconstructing clonal evolution, improved algorithms that can properly handle the identified limitations are greatly needed.

Amino acids in hematologic malignancies: Current status and future perspective

In recent years, growing emphasis has been placed on amino acids and their role in hematologic malignancies. Cancer cell metabolism is altered during tumorigenesis and development to meet expanding energetic and biosynthetic demands. Amino acids not only act as energy-supplying substances, but also play a vital role via regulating key signaling pathways, modulating epigenetic factors and remodeling tumor microenvironment. Targeting amino acids may be an effective therapeutic approach to address the current therapeutic challenges. Here, we provide an updated overview of mechanisms by which amino acids facilitate tumor development and therapy resistance. We also summarize novel therapies targeting amino acids, focusing on recent advances in basic research and their potential clinical implications.

Relapsed Childhood Acute Myeloid Leukemia: Experience from a Single Tertiary Center in Thailand

BACKGROUND

Few studies have examined survival outcomes in relapsed childhood acute myeloid leukemia (AML) in resource-limited countries. This study aimed to evaluate the prognostic factors and survival outcomes of relapsed childhood AML in Thailand.

METHODS

The medical records of AML patients aged 0-15 years treated in a major tertiary center in Southern Thailand between December 1979 and December 2019 were reviewed retrospectively. The overall survival (OS) was calculated using the Kaplan-Meier method.

RESULTS

A total of 316 AML patients were included and relapse occurred in 98 (31%) patients. Of these, 57 (58.2%) and 41 (41.8%) patients had early [≤1 year from first complete remission (CR1)] and late (>1 year from CR1) relapses, respectively. Only 54 (55.1%) patients received chemotherapy after relapse. The 3-year OS of all relapsed patients was 3.5%. The 3-year OS of patients with early and late relapse were 0% and 8.5%, respectively (p=0.002). The 3-year OS of patients who received chemotherapy and those who did not were 6.5% and 0%, respectively (p <0.0001). The median survival time of patients who did not receive chemotherapy was 1.7 months. The 3-year OS of patients who achieved second complete remission (CR2) and those who did not were 12.6% and 0%, respectively (p <0.001).

CONCLUSION

The relapsed AML rate was 31% and the survival outcome was poor with a 3-year OS of 3.5%. The adverse prognostic factors were early relapse, failure to achieve CR2 and those who did not receive chemotherapy after relapse.

Two-drug versus three-drug induction chemotherapy in pediatric acute myeloid leukemia: a randomized controlled trial

The benefit of three-drug induction chemotherapy over a two-drug induction has not been evaluated in pediatric acute myeloid leukemia (AML). We, therefore, conducted a randomized controlled trial to ascertain the benefit of a three-drug induction regimen. Patients aged 1–18 years with newly diagnosed AML were randomized to two cycles of induction chemotherapy with daunorubicin and ara-C (DA) or two cycles of ara-C, daunorubicin, and etoposide (ADE). After induction, patients in both arms received consolidation with two cycles of high-dose ara-C. The study’s primary objective was to compare the event-free survival (EFS) between the two arms. The secondary objectives included comparing the composite complete remission (cCR) rates, overall survival (OS), and toxicities. The study randomized 149 patients, 77 in the DA and 72 in the ADE arm. The median age was 8.7 years, and 92 (62%) patients were males. The median follow-up was 50.9 months. The cCR rate in the DA and ADE arm were 82% and 79% (p = 0.68) after the second induction. There were 13 (17%) induction deaths in the DA arm and 12 (17%) in the ADE arm (p = 0.97). The 5-year EFS in the DA and ADE arm was 34.4% and 34.5%, respectively (p = 0.66). The 5-year OS in the DA and ADE arms was 41.4% and 42.09%, respectively (p = 0.74). There were no significant differences in toxicities between the regimens. There was no statistically significant difference in EFS, OS, CR, or toxicity between ADE and DA regimens in pediatric AML. The trial was registered with the Clinical Trial Registry of India (Reference number: CTRI/2014/11/005202).

Abdominal Complications During Treatment for Pediatric Acute Myeloid Leukemia

Acute myeloid leukemia (AML) accounts for 15% to 20% of childhood leukemias. Because of high-intensive therapy, up to 5% of patients suffer from treatment-related mortality (TRM). Abdominal complications are frequent, however, literature on this subject is sparse. We aimed to characterize severe abdominal pain (AP) and hyperbilirubinemia experienced by pediatric AML patients treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO)-AML 2004 protocol (n=313). Patients were censored at hematopoietic stem cell transplantation and relapse. Toxicity information was collected prospectively. Additional information was requested retrospectively from the treating centers. Sixteen episodes of hyperbilirubinemia and 107 episodes of AP were reported. The treating centers deemed infection (30%) and typhlitis (18%) as the most frequent causes of AP. Six patients developed appendicitis (2%). Patients experiencing concurrent AP and sepsis had a high risk of TRM (36%, n=4). Eighty percent of episodes with hyperbilirubinemia fulfilled the European Society for Bone and Marrow Transplantation criteria for sinusoidal obstruction syndrome. In conclusion, abdominal complications were frequent with infection considered the predominate cause. Most patients with hyperbilirubinemia fulfilled the criteria for sinusoidal obstruction syndrome. AML treatment might be associated with appendicitis. Patients suffering from concurrent AP and sepsis had a high risk of TRM indicating that high awareness of abdominal complications is essential to reduce mortality, especially during sepsis.

Integrative Genomic Analysis of Pediatric Myeloid-Related Acute Leukemias Identifies Novel Subtypes and Prognostic Indicators

Integrating somatic mutation analysis and gene expression profiling distinguishes pediatric AML subtypes with differential prognoses and clinical risks.

Genomic characterization of pediatric patients with acute myeloid leukemia (AML) has led to the discovery of somatic mutations with prognostic implications. Although gene-expression profiling can differentiate subsets of pediatric AML, its clinical utility in risk stratification remains limited. Here, we evaluate gene expression, pathogenic somatic mutations, and outcome in a cohort of 435 pediatric patients with a spectrum of pediatric myeloid-related acute leukemias for biological subtype discovery. This analysis revealed 63 patients with varying immunophenotypes that span a T-lineage and myeloid continuum designated as acute myeloid/T-lymphoblastic leukemia (AMTL). Within AMTL, two patient subgroups distinguished by FLT3-ITD and PRC2 mutations have different outcomes, demonstrating the impact of mutational composition on survival. Across the cohort, variability in outcomes of patients within isomutational subsets is influenced by transcriptional identity and the presence of a stem cell–like gene-expression signature. Integration of gene expression and somatic mutations leads to improved risk stratification.

Unifying heterogeneous expression data to predict targets for CAR-T cell therapy

Chimeric antigen receptor (CAR) T-cell therapy combines antigen-specific properties of monoclonal antibodies with the lytic capacity of T cells. An effective and safe CAR-T cell therapy strategy relies on identifying an antigen that has high expression and is tumor specific. This strategy has been successfully used to treat patients with CD19+ B-cell acute lymphoblastic leukemia (B-ALL). Finding a suitable target antigen for other cancers such as acute myeloid leukemia (AML) has proven challenging, as the majority of currently targeted AML antigens are also expressed on hematopoietic progenitor cells (HPCs) or mature myeloid cells. Herein, we developed a computational method to perform a data transformation to enable the comparison of publicly available gene expression data across different datasets or assay platforms. The resulting transformed expression values (TEVs) were used in our antigen prediction algorithm to assess suitable tumor-associated antigens (TAAs) that could be targeted with CAR-T cells. We validated this method by identifying B-ALL antigens with known clinical effectiveness, such as CD19 and CD22. Our algorithm predicted TAAs being currently explored preclinically and in clinical CAR-T AML therapy trials, as well as novel TAAs in pediatric megakaryoblastic AML. Thus, this analytical approach presents a promising new strategy to mine diverse datasets for identifying TAAs suitable for immunotherapy.

Effectiveness and antimicrobial susceptibility profiles during primary antimicrobial prophylaxis for pediatric acute myeloid leukemia

Limited data are available on antimicrobials exposure and microbiology evolution in pediatric acute myeloid leukemia (AML) patients underwent antimicrobials prophylaxis. To assess the effectiveness of antimicrobials prophylaxis, antibiotic susceptibilities of bacteria, and exposure of antimicrobials during intensive chemotherapy for AML patients, 90 consecutive de novo AML patients aged 0–18 years between January 1, 1997 and March 31, 2018 were enrolled. Vancomycin, ciprofloxacin and voriconazole prophylaxis was administered from January 1, 2010. During the preprophylaxis period, January 1997 to December 2009, 62 patients experienced a total of 87 episodes of bloodstream infection (BSI) and 17 episodes of invasive fungal infection (IFI) among 502 courses of chemotherapy. In contrast, 16 episodes of BSI occurred and no IFIs were reported to occur in 28 patients who received 247 courses of chemotherapy in the prophylaxis period. Patients who received antimicrobial prophylaxis had a significant reduction of BSI, IFI, and febrile neutropenia in comparison with patients without prophylaxis. Exposure to amikacin, carbapenem, amphotericin B was reduced in the prophylaxis period. Imipenem susceptibility of Enterobacter cloacae as well as vancomycin susceptibility of Enterococcus species were reduced in the prophylaxis period. At the time of the last follow up, patients with prophylaxis had a better subsequent 5-year overall survival rate than those without prophylaxis. Prophylactic antimicrobials administration in children with AML who undergo chemotherapy can significantly reduce the rates of life-threatening infection, exposure to antimicrobials, and might result in a better outcome.

Late outcomes in survivors of childhood acute myeloid leukemia: a report from the St. Jude Lifetime Cohort Study

Cumulative burden of chronic health conditions and neurocognitive and physical function were examined among survivors of childhood acute myeloid leukemia (AML) treated with hematopoietic cell transplant (HCT; n = 66) or conventional therapy (CT; n = 67). Survivors and controls underwent a comprehensive clinical assessment, and health conditions were graded using a modified version of the Common Terminology Criteria for Adverse Events. By age 40 years, HCT and CT survivors had an average 17.4 (95% confidence interval [CI] 14.6-20.1) and 9.3 (7.7-11.1) grade 1-4 conditions versus 3.8 (3.3-4.2) in community controls. Compared to controls, HCT survivors had a higher prevalence of hypertriglyceridemia (45.5% vs. 18.3%), hypercholesterolemia (47.0% vs. 30.9%), hypothyroidism (27.3% vs. 4.0%), and primary hypogonadism (p < 0.001). CT survivors had a higher prevalence of cardiomyopathy (11.9% vs. 2.7%) and hypertension (53.7% vs. 44.3%). Neurocognitive impairment was elevated across all domains compared to controls but did not differ by treatment modality. Compared to controls, a higher proportion of HCT survivors had impairments in strength and endurance; whereas flexibility and mobility impairments were noted among CT survivors. Despite successful advances in childhood AML therapy, many therapeutic exposures remain unchanged. These findings support ongoing investigations of novel therapies and strategies to ameliorate the risk of late morbidities.

Current Status of CAR T Cell Therapy for Leukemias

OPINION STATEMENT

Chimeric antigen receptor (CAR) T-cell therapy has become the standard of care for children and young adults with relapsed and refractory B-cell acute lymphoblastic leukemia (B-ALL), and it is a highly promising therapy under investigation for adults with relapsed disease. Despite having potentially life-threatening toxicities, such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, the benefits of CAR T-cell therapy far outweigh these risks, particularly as increased experience and improved supportive care measures are mitigating these toxicities. CAR T cells can result in complete remission for significant proportion of patients with relapsed and refractory B-ALL and permit them to proceed to potentially curative allogeneic hematopoietic stem cell transplantation (allo-HSCT). CAR T cells may also be curative by themselves. Herein lie the greatest challenges and questions for clinical investigators, specifically, how are CAR T cells best employed and how do we overcome mechanisms of resistance to them? The primary clinical question is the timing and even the necessity of allo-HSCT. Relative to resistance, we know that target antigen loss, specifically CD19, is a major contributor to resistance. However, current investigations of alternative targets, such CD22, and CAR T cells expressing dual targeting antigen receptors have demonstrated encouraging initial results and provide a high degree of optimism that the efficacy and the broader application of CAR T-cell therapy will gradually increase in B-ALL. That optimism is not as high and the challenges are increased for the application of CAR T cells in T-cell leukemias and acute myeloid leukemia due to the relative lack of suitable leukemia surface targets that are not also expressed on normal hematopoietic progenitors. Despite these significant challenges, considerable research is being conducted into the development of CAR T cells for these diseases utilizing unique technologies, which may be applicable to other diseases.

Innovative Approaches in the Battle Against Cancer Recurrence: Novel Strategies to Combat Dormant Disseminated Tumor Cells

Cancer recurrence remains a great fear for many cancer survivors following their initial, apparently successful, therapy. Despite significant improvement in the overall survival of many types of cancer, metastasis accounts for ~90% of all cancer mortality. There is a growing understanding that future therapeutic practices must accommodate this unmet medical need in preventing metastatic recurrence. Accumulating evidence supports dormant disseminated tumor cells (DTCs) as a source of cancer recurrence and recognizes the need for novel strategies to target these tumor cells. This review presents strategies to target dormant quiescent DTCs that reside at secondary sites. These strategies aim to prevent recurrence by maintaining dormant DTCs at bay, or eradicating them. Various approaches are presented, including: reinforcing the niche where dormant DTCs reside in order to keep dormant DTCs at bay; promoting cell intrinsic mechanisms to induce dormancy; preventing the engagement of dormant DTCs with their supportive niche in order to prevent their reactivation; targeting cell-intrinsic mechanisms mediating long-term survival of dormant DTCs; sensitizing dormant DTCs to chemotherapy treatments; and, inhibiting the immune evasion of dormant DTCs, leading to their demise. Various therapeutic approaches, some of which utilize drugs that are already approved, or have been tested in clinical trials and may be considered for repurposing, will be discussed. In addition, clinical evidence for the presence of dormant DTCs will be reviewed, along with potential prognostic biomarkers to enable the identification and stratification of patients who are at high risk of recurrence, and who could benefit from novel dormant DTCs targeting therapies. Finally, we will address the shortcomings of current trial designs for determining activity against dormant DTCs and provide novel approaches.

Treatment outcomes of pediatric acute myeloid leukemia: a retrospective analysis from 1996 to 2019 in Taiwan

Improvement in outcomes of children with acute myeloid leukemia (AML) is attributed to several refinements in clinical management. We evaluated treatment outcomes of Taiwanese pediatric AML patients in the past 20 years. Overall, 860 de novo AML patients aged 0-18 years and registered in the Childhood Cancer Foundation of R.O.C during January 1996-December 2019 were included. Survival analysis was performed to identify factors that improved treatment outcomes. Regardless of treatment modalities used, patients during 2008-2019 had better 5-year event-free survival (EFS) and overall survival (OS) rates than patients during 1996-2007. For patients received the TPOG-AML-97A treatment, only 5-year OS rates were significantly different between patients diagnosed before and after 2008. Patients with RUNX1-RUNX1T1 had similar relapse-free survival rates, but 5-year OS rates were better during 2008-2019. However, the survival of patients who received hematopoietic stem-cell transplantations (HSCT) did not differ significantly before and after 2008. For patients without relapse, the 5-year OS improved during 2008-2019. Non-relapse mortality decreased annually, and cumulative relapse rates were similar. In conclusion, 5-year EFS and OS rates improved during 2008-2019, though intensities of chemotherapy treatments were similar before and after 2008. Non-relapse mortality decreased gradually. Further treatment strategies including more intensive chemotherapy, novel agents' use, identification of high-risk patients using genotyping and minimal residual disease, early intervention of HSCT, and antibiotic prophylaxis can be considered for future clinical protocol designs in Taiwan.

Pharmacokinetics of alemtuzumab in pediatric patients undergoing ex vivo T-cell-depleted haploidentical hematopoietic cell transplantation

PURPOSE

Alemtuzumab is a humanized monoclonal antibody against CD52 which is predominantly present on T and B lymphocytes. Alemtuzumab has been used as part of conditioning regimens for prophylaxis against rejection and GVHD. While the mechanism of action is well understood, the pharmacokinetics of this drug in children needed to be studied in more detail especially in the setting of ex vivo T-cell-depleted hematopoietic cell transplantation (HCT).

METHODS

Serum alemtuzumab levels were measured at various time points in 13 patients who underwent haploidentical HCT utilizing ex vivo donor T-cell depletion. Alemtuzumab was administered subcutaneously at a cumulative dose of 45 mg/m² from days - 13 to - 11. A one-compartmental model was used to fit the data using non-linear mixed effects modeling.

RESULTS

We determined the median half-life to be 11 days. Alemtuzumab clearance increased with increasing baseline lymphocyte count (p = 0.008). Additionally, clearance increased with weight and age (p ≤ 0.035). AUC of alemtuzumab did not have any significant relationship with type of leukemia, overall survival, engraftment, immune reconstitution, mixed chimerism or GVHD, although the number of subjects in this pilot study was limited.

CONCLUSION

Absolute lymphocyte count and body weight affect alemtuzumab clearance. We also demonstrate feasibility of body-surface area-based dosing of alemtuzumab in pediatric HCT patients. Further studies are needed to evaluate the role of monitoring alemtuzumab serum concentrations to balance the prevention of graft rejection and GVHD with the promotion of rapid donor immune reconstitution.

Distance to treatment center is associated with survival in children and young adults with acute lymphoblastic leukemia

BACKGROUND

Socioeconomic and demographic categories such as income, race, insurance status, and treatment center type are associated with outcomes in acute leukemia. This study was aimed at determining whether the distance to treatment center affects overall survival for children and young adults with acute leukemia.

METHODS

The National Cancer Database was queried for patients 39 years old or younger who were diagnosed with acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL). A backward elimination procedure was used to select final multivariate Cox models.

RESULTS

In total, 12,301 patients with AML and 22,683 patients with ALL were analyzed. The ALL model included distance to treatment center, Charlson-Deyo score, age, race, insurance status, and community income level. US census definitions of urban and rural were not statistically significant, and no interaction was significant for included variables. Compared with distances > 50 miles, all other distances were associated with improved survival (hazard ratio [HR] for ≤10 miles, 0.91; P = .04; HR for >10 to ≤20 miles, 0.86; P = .004; HR for >20 to ≤50 miles, 0.87; P = .005). The final model for AML included the same variables as the ALL model except for distance to treatment center, which was not statistically significant.

CONCLUSIONS

For children and young adults with ALL, distances > 50 miles are associated with inferior overall survival; however, no difference is seen for AML. Although it is unknown whether differences in survival for patients with ALL based on distance are driven by relapse or treatment-related mortality, increased attention to adherence, supportive care, and logistics for patients traveling long distances is warranted.

LAY SUMMARY

For children and young adults with acute lymphoblastic leukemia, living more than 50 miles from the treatment center is associated with worse outcomes.

Pediatric cancer mortality and survival in the United States, 2001-2016

BACKGROUND

Although pediatric cancer mortality and survival have improved in the United States over the past 40 years, differences exist by age, race/ethnicity, cancer site, and economic status. To assess progress, this study examined recent mortality and survival data for individuals younger than 20 years.

METHODS

Age-adjusted death rates were calculated with the National Vital Statistics System for 2002-2016. Annual percent changes (APCs) and average annual percent changes (AAPCs) were calculated with joinpoint regression. Five-year relative survival was calculated on the basis of National Program of Cancer Registries data for 2001-2015. Death rates and survival were estimated overall and by sex, 5-year age group, race/ethnicity, cancer type, and county-based economic markers.

RESULTS

Death rates decreased during 2002-2016 (AAPC, -1.5), with steeper declines during 2002-2009 (APC, -2.6), and then plateaued (APC, -0.4). Leukemia and brain cancer were the most common causes of death from pediatric cancer, and brain cancer surpassed leukemia in 2011. Death rates decreased for leukemia and lymphoma but were unchanged for brain, bone, and soft-tissue cancers. From 2001-2007 to 2008-2015, survival improved from 82.0% to 85.1%. Survival was highest in both periods among females, those aged 15 to 19 years, non-Hispanic Whites, and those in counties in the top 25% by economic status. Survival improved for leukemias, lymphomas, and brain cancers but plateaued for bone and soft-tissue cancers.

CONCLUSIONS

Although overall death rates have decreased and survival has increased, differences persist by sex, age, race/ethnicity, cancer type, and economic status. Improvements in pediatric cancer outcomes may depend on improving therapies, access to care, and supportive and long-term care.

Prognostic Factors in Childhood Acute Myeloid Leukemia; Experience from A Developing Country

BACKGROUND

In the developed world, 5-years survival of childhood acute myeloid leukaemia (AML) has improved to 70%. However, the survival rates in the developing world are below 40%. The main contributing factors to these reduced survival rates are a late presentation, malnutrition and high treatment-related mortality.

AIM

To document the factors affecting treatment outcome of childhood AML at a tertiary care facility of Pakistan.

METHODS AND RESULTS

All newly registered cases of AML under 18 years of age from January 1, 2012 onwards who completed their treatment before November 30, 2019 were included. Data of 219 cases of AML containing 140 (63.9%) males and 79 (36.1%) females was analyzed. The mean age was 6.30 ± 3.66 years. Pallor was the commonest presenting features in 180 (82.2%) and M2 was the commonest French American-British (FAB) subtype in 103 (47.0%) cases. In univariate analysis, high white blood cells (WBC) count at presentation (P = .006), poor nutritional status (P = .005), unfavourable cytogenetics (P = .019), certain types of FAB AML subtype (P = .005), and use of etoposide in induction chemotherapy (P = .042) significantly adversely affected overall survival (OS). Neutropenic sepsis and bleeding were the major causes of treatment-related mortality. Response to induction chemotherapy was the most significant prognostic factor in the multivariate analysis (P = <.001). After a median follow-up of 40.96 ± 26.23 months, 5-year OS and DFS of the cohort were 40.6% and 38.3% respectively.

CONCLUSIONS

In this largest cohort of childhood AML from Pakistan, high WBC count at presentation, malnutrition, unfavourable cytogenetics and use of etoposide during induction chemotherapy were associated with decreased OS and DFS rates. Response to the induction chemotherapy was the most significant prognostic factor.

Causes of early death and treatment-related death in newly diagnosed pediatric acute myeloid leukemia: Recent experiences of the Dutch Childhood Oncology Group

BACKGROUND

With the current more effective treatment regimens for pediatric acute myeloid leukemia (AML), research on early death (ED), treatment-related mortality (TRM), and toxicity becomes increasingly important. The aim of this study was to give an overview of the frequency, clinical features, and risk factors associated with ED and TRM in first complete remission (CR1) during the last three consecutive treatment protocols of the Dutch Childhood Oncology Group (DCOG) between 1998 and 2014.

METHODS

Incidence and risk factors associated with ED and TRM in CR1 were retrospectively studied in 245 patients treated according to the Dutch ANLL-97/AML-12 (n = 118), AML-15 (n = 60), or DB AML-01 (n = 67) protocols.

RESULTS

The incidence of ED was, respectively, 5.1%, 6.7%, and 3.0% excluding deaths before treatment (P = NS), and 7.4%, 11.1%, and 4.4% including deaths before the onset of treatment. Severe underweight at initial diagnosis was significantly associated with more frequent ED. When relapse was included as a competing risk, cumulative incidence of death in CR1 were 5.9%, 5.0%, and 4.6% for ANLL97, AML15, and DB01, respectively (P = NS). The most important cause of TRM included infectious and SCT-related complications.

CONCLUSION

We report relatively stable rates of ED and TRM in CR1 in the latest completed DCOG protocols for newly diagnosed AML patients. The most important causes of TRM were SCT- or infection-related, warranting further evaluation and awareness.

Optimum Induction Chemotherapy for Pediatric Acute Myeloid Leukemia: Experience From A Developing Country

OBJECTIVES

Treatment outcome in children with acute myeloid leukemia (AML) has improved in the developed world but remains poor in developing countries. We assessed the role of etoposide in induction chemotherapy in pediatric AML.

METHODS

This analysis retrospectively compared 2 induction chemotherapy regimens consisting of daunorubicin and cytarabine with etoposide (ADE) and without etoposide (AD). All newly diagnosed cases of AML younger than 18 years from January 1, 2012, onwards who completed their treatment before January 31, 2019, were included. Data of 186 cases, including 117 males (62.9%) and 69 females (37.1%), were analyzed. Demographic, initial presentation blood counts, and AML subtypes were almost identical in both groups.

RESULTS

Complete remission rates were almost identical for the ADE versus the AD group (78.8% vs 80.0%, p = 0.980). Treatment-related mortality was higher, albeit not significantly, in the ADE (25 of 105; 23.8%) versus the AD (16 of 81; 19.8%) group (p = 0.508). Overall survival was 32 of 105 (30.5%) in the ADE and 43 of 81 (53.1%) in the AD group (p = 0.079), and disease-free survival was 29 of 105 (27.6%) and 39 of 81 (48.1%) in ADE and AD groups (p = 0.056), respectively.

CONCLUSIONS

Etoposide in induction treatment of pediatric AML is associated with increased episodes of bacterial and fungal infections and high treatment-related mortality. Moreover, it does not offer any survival benefit. In low- and middle-income countries like Pakistan, it should not be used in the induction treatment protocol.

Impact of fluid overload and infection on respiratory adverse event development during induction therapy for childhood acute myeloid leukemia

BACKGROUND

Treatment-related morbidity and mortality occur frequently in childhood acute myeloid leukemia (AML) induction. Yet the contributions of respiratory adverse events (AEs) within this population are poorly understood. Furthermore, the roles of fluid overload (FO) and infection in AML pulmonary complications have been inadequately examined.

OBJECTIVES

To describe the incidence, categories, and grades of respiratory AEs and to assess the associations of FO and infection on respiratory AE development in childhood AML induction.

METHODS

We retrospectively examined the induction courses of a cohort of de novo pediatric AML patients for any NCI CTCAE grade 2 to 5 respiratory AE, FO, and systemic/pulmonary infection occurrence. Demographic, disease, and treatment-related data were abstracted. Descriptive, univariate, survival, and multivariable analyses were conducted.

RESULTS

Among 105 eligible subjects from 2009 to 2016, 49.5% (n = 52) experienced 63 discrete respiratory AEs. FO occurred in 28.6% of subjects (n = 30), with half occurring within 24 hours of hospitalization. Positive FO status < 10 days (aHR 5.5, 95% CI 2.3-12.8), ≥ 10 days (aHR 13, 95% CI 4.1-41.8), and positive infection status ≥ 10 days into treatment (aHR 14.9, 5.4-41.6) were each independently associated with AE development.

CONCLUSIONS

We describe a higher incidence of respiratory AEs during childhood AML induction than previously illustrated. FO occurs frequently and early in this course. Late infections and FO at any time frame were strongly associated with AE development. Interventions focused on the prevention and management of FO and infectious respiratory complications could be instrumental in reducing preventable treatment-related morbidity and mortality.

Derivation of Anthracycline and Anthraquinone Equivalence Ratios to Doxorubicin for Late-Onset Cardiotoxicity

IMPORTANCE

Anthracyclines are part of many effective pediatric cancer treatment protocols. Most pediatric oncology treatment groups assume that the hematologic toxicity of anthracycline agents is equivalent to their cardiotoxicity; for example, Children's Oncology Group substitution rules consider daunorubicin and epirubicin isoequivalent to doxorubicin, whereas mitoxantrone and idarubicin are considered 4 to 5 times as toxic as doxorubicin.

OBJECTIVE

To determine optimal dose equivalence ratios for late-onset cardiomyopathy between doxorubicin and other anthracyclines or the anthraquinone mitoxantrone.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study of childhood cancer survivors who survived 5 or more years analyzed data pooled from 20 367 participants in the Childhood Cancer Survivor Study treated from 1970 to 1999, 5741 participants in the Dutch Childhood Oncology Group LATER study diagnosed between 1963 and 2001, and 2315 participants in the St Jude Lifetime study treated from 1962 to 2005.

EXPOSURES

Cumulative doses of each agent (the anthracyclines doxorubicin, daunorubicin, epirubicin, and idarubicin; and the anthraquinone mitoxantrone) along with chest radiotherapy exposure were abstracted from medical records.

MAIN OUTCOMES AND MEASURES

Cardiomyopathy (severe, life-threatening, or fatal) by 40 years of age. Agent-specific Cox proportional hazards models evaluated cardiomyopathy risk, adjusting for chest radiotherapy, age at cancer diagnosis, sex, and exposure to anthracyclines or to an anthraquinone. An agent-specific cardiomyopathy equivalence ratio (relative to doxorubicin) was estimated for each dose category as a ratio of the hazard ratios, and then a weighted mean determined the overall agent-specific equivalence ratio across all dose categories.

RESULTS

Of 28 423 survivors (46.4% female; median age at cancer diagnosis 6.1 years [range, 0.0-22.7 years]), 9330 patients received doxorubicin, 4433 received daunorubicin, 342 received epirubicin, 241 received idarubicin, and 265 received mitoxantrone. After a median follow-up of 20.0 years (range, 5.0-40.0 years) following receipt of a cancer diagnosis, 399 cardiomyopathy cases were observed. Relative to doxorubicin, the equivalence ratios were 0.6 (95% CI, 0.4-1.0) for daunorubicin, 0.8 (95% CI, 0.5-2.8) for epirubicin, and 10.5 (95% CI, 6.2-19.1) for mitoxantrone. Outcomes were too rare to generate idarubicin-specific estimates. Ratios based on a continuous linear dose-response relationship were similar for daunorubicin (0.5 [95% CI, 0.4-0.7]) and epirubicin (0.8 [95% CI, 0.3-1.4]). The relationship between mitoxantrone and doxorubicin appeared better characterized by a linear exponential model.

CONCLUSIONS AND RELEVANCE

In a large data set assembled to examine long-term cardiomyopathy risk in childhood cancer survivors, daunorubicin was associated with decreased cardiomyopathy risk vs doxorubicin, whereas epirubicin was approximately isoequivalent. By contrast, the current hematologic-based doxorubicin dose equivalency of mitoxantrone (4:1) appeared to significantly underestimate the association of mitoxantrone with long-term cardiomyopathy risk.

Synthetic Lethality of Wnt Pathway Activation and Asparaginase in Drug-Resistant Acute Leukemias

Resistance to asparaginase, an antileukemic enzyme that depletes asparagine, is a common clinical problem. Using a genome-wide CRISPR/Cas9 screen, we found a synthetic lethal interaction between Wnt pathway activation and asparaginase in acute leukemias resistant to this enzyme. Wnt pathway activation induced asparaginase sensitivity in distinct treatment-resistant subtypes of acute leukemia, but not in normal hematopoietic progenitors. Sensitization to asparaginase was mediated by Wnt-dependent stabilization of proteins (Wnt/STOP), which inhibits glycogen synthase kinase 3 (GSK3)-dependent protein ubiquitination and proteasomal degradation, a catabolic source of asparagine. Inhibiting the alpha isoform of GSK3 phenocopied this effect, and pharmacologic GSK3α inhibition profoundly sensitized drug-resistant leukemias to asparaginase. Our findings provide a molecular rationale for activation of Wnt/STOP signaling to improve the therapeutic index of asparaginase.

Prognostic impact of t(16;21)(p11;q22) and t(16;21)(q24;q22) in pediatric AML: a retrospective study by the I-BFM Study Group

To study the prognostic relevance of rare genetic aberrations in acute myeloid leukemia (AML), such as t(16;21), international collaboration is required. Two different types of t(16;21) translocations can be distinguished: t(16;21)(p11;q22), resulting in the FUS-ERG fusion gene; and t(16;21)(q24;q22), resulting in RUNX1-core binding factor (CBFA2T3). We collected data on clinical and biological characteristics of 54 pediatric AML cases with t(16;21) rearrangements from 14 international collaborative study groups participating in the international Berlin-Frankfurt-Münster (I-BFM) AML study group. The AML-BFM cohort diagnosed between 1997 and 2013 was used as a reference cohort. RUNX1-CBFA2T3 (n = 23) had significantly lower median white blood cell count (12.5 × 10⁹/L, P = .03) compared with the reference cohort. FUS-ERG rearranged AML (n = 31) had no predominant French-American-British (FAB) type, whereas 76% of RUNX1-CBFA2T3 had an M1/M2 FAB type (M1, M2), significantly different from the reference cohort (P = .004). Four-year event-free survival (EFS) of patients with FUS-ERG was 7% (standard error [SE] = 5%), significantly lower compared with the reference cohort (51%, SE = 1%, P < .001). Four-year EFS of RUNX1-CBFA2T3 was 77% (SE = 8%, P = .06), significantly higher compared with the reference cohort. Cumulative incidence of relapse was 74% (SE = 8%) in FUS-ERG, 0% (SE = 0%) in RUNX1-CBFA2T3, compared with 32% (SE = 1%) in the reference cohort (P < .001). Multivariate analysis identified both FUS-ERG and RUNX1-CBFA2T3 as independent risk factors with hazard ratios of 1.9 (P < .0001) and 0.3 (P = .025), respectively. These results describe 2 clinically relevant distinct subtypes of pediatric AML. Similarly to other core-binding factor AMLs, patients with RUNX1-CBFA2T3 rearranged AML may benefit from stratification in the standard risk treatment, whereas patients with FUS-ERG rearranged AML should be considered high-risk.

Advances in immunotherapy for pediatric acute myeloid leukemia

INTRODUCTION

Achieving better disease control in patients diagnosed with acute myeloid leukemia (AML) has proven challenging. Overall survival has been impacted by addressing treatment related mortality with focused supportive care measures. Despite this improvement, it remains difficult to induce durable leukemia remissions despite aggressive chemotherapeutic regimens. The addition of hematopoietic stem cell transplants (HSCT) has allowed further treatment intensification and provided the benefit of graft-versus-leukemia (GVL) effect. However, HSCT carries the risk of transplant related morbidities, particularly GVHD, and anti-tumor responsiveness is still suboptimal. Thus, there is a need for alternate therapies. Immunotherapy has the potential to address this need. Areas covered: Expert opinion: The elusiveness of an ideal surface antigen target together with an immunosuppressive leukemic microenvironment add to the already difficult challenge in developing AML-targeted immunotherapies. Though many hurdles remain, recent translational discovery and progressive clinical advances anticipate exciting future developments.

AREAS COVERED

This review highlights promises and challenges to immune-based therapies for AML. It aims to summarize immunotherapeutic strategies trialed in AML patients to date, inclusive of: antibodies, vaccines, and cellular therapy. It emphasizes those being used in the pediatric population, but also includes adult clinical trials and translational science that may ultimately extend to pediatric patients.

Targeting FLT3 Signaling in Childhood Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the second most common leukemia of childhood and is associated with high rates of chemotherapy resistance and relapse. Clinical outcomes for children with AML treated with maximally intensive multi-agent chemotherapy lag far behind those of children with the more common acute lymphoblastic leukemia, demonstrating continued need for new therapeutic approaches to decrease relapse risk and improve long-term survival. Mutations in the FMS-like tyrosine kinase-3 receptor gene (FLT3) occur in approximately 25% of children and adults with AML and are associated with particularly poor prognoses. Identification and development of targeted FLT3 inhibitors represents a major precision medicine paradigm shift in the treatment of patients with AML. While further development of many first-generation FLT3 inhibitors was hampered by limited potency and significant toxicity due to effects upon other kinases, the more selective second- and third-generation FLT3 inhibitors have demonstrated excellent tolerability and remarkable efficacy in the relapsed/refractory and now de novo FLT3-mutated AML settings. While these newest and most promising inhibitors have largely been studied in the adult population, pediatric investigation of FLT3 inhibitors with chemotherapy is relatively recently ongoing or planned. Successful development of FLT3 inhibitor-based therapies will be essential to improve outcomes in children with this high-risk subtype of AML.