CD123 Expression Is Associated With High-Risk Disease Characteristics in Childhood Acute Myeloid Leukemia: A Report From the Children's Oncology Group

PURPOSE Increased CD123 surface expression has been associated with high-risk disease characteristics in adult acute myeloid leukemia (AML), but has not been well-characterized in childhood AML. In this study, we defined CD123 expression and associated clinical characteristics in a uniformly treated cohort of pediatric patients with newly diagnosed AML enrolled on the Children's Oncology Group AAML1031 phase III trial ( NCT01371981 ). MATERIALS AND METHODS AML blasts within diagnostic bone marrow specimens (n = 1,040) were prospectively analyzed for CD123 protein expression by multidimensional flow cytometry immunophenotyping at a central clinical laboratory. Patients were stratified as low-risk or high-risk on the basis of (1) leukemia-associated cytogenetic and molecular alterations and (2) end-of-induction measurable residual disease levels. RESULTS The study population was divided into CD123 expression–based quartiles (n = 260 each) for analysis. Those with highest CD123 expression (quartile 4 [Q4]) had higher prevalence of high-risk KMT2A rearrangements and FLT3-ITD mutations ( P < .001 for both) and lower prevalence of low-risk t(8;21), inv(16), and CEBPA mutations ( P < .001 for all). Patients in lower CD123 expression quartiles (Q1-3) had similar relapse risk, event-free survival, and overall survival. Conversely, Q4 patients had a significantly higher relapse risk (53% v 39%, P < .001), lower event-free survival (49% v 69%, P < .001), and lower overall survival (32% v 50%, P < .001) in comparison with Q1-3 patients. CD123 maintained independent significance for outcomes when all known contemporary high-risk cytogenetic and molecular markers were incorporated into multivariable Cox regression analysis. CONCLUSION CD123 is strongly associated with disease-relevant cytogenetic and molecular alterations in childhood AML. CD123 is a critical biomarker and promising immunotherapeutic target for children with relapsed or refractory AML, given its prevalent expression and enrichment in patients with high-risk genetic alterations and inferior clinical outcomes with conventional therapy.

KMT2A Partial Tandem Duplications (KMT2A-PTD) Is a Rare, but Recurrent Genomic Event in Childhood AML and Associated with High Rate of Co-Occurring FLT3 Mutations

KMT2A partial tandem duplication (KMT2A-PTD), characterized by a large internal duplication spanning 6-8 exons, has been documented in adult AML with a prevalence of 3-10% and is associated with poor outcomes. Despite the high prevalence of KTM2A fusions and known associated outcomes, prevalence and clinical implications of KMT2A-PTD has not been well characterized in childhood AML. We interrogated the transcriptome and associated clinical and genomic data from pediatric AML patients treated on COG AAML1031 to define the prevalence of KMT2A-PTD, frequency of co-occurring genetic mutations and outcomes associated with this variant. Ribo-depleted RNA seq data from 1,294 patients with AML (age 0-29 years) enrolled on COG AAML1031 with available cytogenetic, molecular, and clinical data were utilized. Gene fusions, internal tandem duplications (ITD) and partial tandem duplications (PTD) were detected by Cicero. Conventional karyotyping and mutational analysis including NGS were used to determine additional cytogenetic and molecular abnormalities. Response was measured by 5-year overall survival (OS), event-free survival (EFS), disease-free survival (DFS) and relapse risk (RR). Of the 1,294 patients studied, KMT2A-PTD was identified in 20 patients (1.5%). Evaluation of karyotype demonstrated striking paucity of karyotypic alterations with 75% with normal karyotype; 3 cases (15%) of trisomy 11 were identified. In contrast to KMT2A-rearranged (KMT2A-r) AML, which has the highest prevalence in young patients (median age 3.3 years), the median age with KMT2A-PTD was 13.4 years (p&lt;0.0001). Further analysis demonstrated a high rate of co-occurrence of FLT3 mutations; 15 patients (75%) had FLT3-ITD (N=13; 65%) and/or FLT3 activating mutations (N=5; 25%). The rate of co-occurring FLT3-ITD was significantly higher in the KMT2A-PTD cohort compared to patients without KMT2A-PTD (65% vs. 19%, p&lt;0.001). Prevalence of KMT2A-PTD in patients with FLT3-ITD was 5.7%. Additional co-occurring genetic mutations were identified in WT1 (20%) and the RAS pathway. There was a striking enrichment of mutations that are commonly associated with AML in older adults with 8/20 patients (40%) harboring mutations in IDH1/IDH2, U2AF1, and TP53, far in excess of what is seen in other pediatric AML patients (Figure 1A). We evaluated the significance of KMT2A-PTD on clinical outcome. Patients with KMT2A-PTD had a poor response to induction therapy with a morphologic CR rate of 45% and rate of residual disease (MRD) positivity by flow cytometry after initial course of therapy was 40%. Additionally, high rates of relapse were noted for patients with KMT2A-PTD with a RR of 53%. EFS for patients with and without KMT2A-PTD was 39% vs. 46%, respectively (p=0.54) with a corresponding OS of 58% and 64% (p=0.61). Outcome analysis for the KMT2A-PTD cohort demonstrated dual KMT2A-PTD/FLT3-ITD patients had an EFS of 46% compared to 29% for KMT2A-PTD/non-ITD patients (p=0.62, Figure 1B). We inquired whether hematopoietic stem cell transplant (HSCT) may modify outcomes in patients with KMT2A-PTD. Of the 20 patients with KMT2A-PTD, 7 (35%) proceeded to HSCT in CR1, with the indication in 6 of 7 patients due to FLT3-ITD high allelic ratio (HAR, ≥0.4). Stem cell transplant recipients had a DFS of 83% vs. 0% for those who continued on protocol chemotherapy (p=0.002, Figure 1C) with corresponding OS of 100% vs. 43%, respectively (p=0.05). In this large cohort of childhood AML patients treated on AAML1031, we identified a small subset of patients with KMT2A-PTD and show the high prevalence of co-occurring FLT3 mutations. Although KMT2A-PTD patients with and without FLT3-ITD had similar outcomes, the cohort who received HSCT in CR1 (most with FLT3-ITD) experienced improved outcomes compared to the rest of the cohort, suggesting that intensification of therapy may benefit this group of patients overall. Further research into KMT2A-PTD in pediatric AML will guide future risk-adapted therapy and enhance understanding of biologic implications of this lesion, including whether altered KMT2A may serve as a therapeutic target as it may for KMT2A-r AML. Figure 1 Figure 1. Disclosures Pollard: Syndax: Membership on an entity's Board of Directors or advisory committees; Kura Oncology: Membership on an entity's Board of Directors or advisory committees.

Bilateral Orbital Extension of Acute Myeloid Leukemia Masquerading as Burkitt Lymphoma: A Case Report

We report the case of a three-year-old girl with left sided facial swelling and proptosis as the initial presentation of bilateral orbit involving Acute Myeloid Leukemia (AML) in Cameroon. Despite being less typical in childhood, AML is the most common leukemia to cause orbital leukemic tumors. Solid extramedullary AML involves the orbit in 30% of cases and is bilateral in one third patients

Biomarkers Associated with CD8+ T Cell Infiltration in Childhood AML

Acute myeloid leukemia (AML) is a common hematological malignant tumor in children. AML is characterized by high morbidity, recurrence and mortality rates worldwide. Immune cell infiltration in tumor microenvironment plays an important role in tumor progression. This study aimed at exploring biomarkers related to CD8+T cell infiltration in children with AML. Transcriptome data and clinical data were retrieved from TARGET database. We collected whole blood samples from some AML children to verify the results. Through the joint analysis of the data of multiple databases we found that CAMK2D, MPZL3, MSL3 are associated with CD8+ immune infiltration. Through PCR analysis, it was found that CAMK2D, MPZL3, MSL3 was highly expressed in the whole blood of children with AML. Analysis showed that CAMK2D, MPZL3 and MSL3 are potential clinical prognostic markers related to CD8+T cell infiltration in children with AML. The findings of this study show that CAMK2D, MPZL3, MSL3 are implicated in prognosis of AML. Notably, the three genes are implicated in CD8+T cells-related pathways.

Cytogenetic and mutational analysis and outcome assessment of a cohort of 284 children with de novo acute myeloid leukemia reveal complex karyotype as an adverse risk factor for inferior survival

Background Acute myeloid leukemia (AML) is rare in children. Although complex karyotype (CK) defined as ≥ 3 cytogenetic abnormalities is an adverse risk factor in adult AML, its prognostic impact on childhood AML remains to be determined. Results We studied the prevalence, cytogenetic and mutational features, and outcome impact of CK in a cohort of 284 Chinese children with de novo AML. Thirty-four (12.0%) children met the criteria for CK-AML with atypical CK being more frequent than typical CK featured with -5/5q-, -7/7q-, and/or 17p aberration. Mutational prevalence was low and co-occurrence mutants were uncommon. Children with CK-AML showed shorter overall survival (OS) (5-year OS: 26.7 ± 10.6% vs. 37.5 ± 8.6%, p = 0.053) and event-free survival (EFS) (5-year EFS: 26.7 ± 10.6% vs. 38.8 ± 8.6%, p = 0.039) compared with those with intermediate-risk genetics. Typical CK tended to correlate with a decreased OS than atypical CK (5-year OS: 0 vs. 33 ± 12.7%.; p = 0.084), and CK with ≥ 5 cytogenetic aberrations was associated with an inferior survival compared with CK with ≤ 4 aberrations (5-year OS: 13.6 ± 11.7% vs. 50.0 ± 18.6%; p = 0.040; 5-year EFS: 13.6 ± 11.7% vs. 50.0 ± 18.6%; p = 0.048). Conclusion Our results demonstrate CK as an adverse risk factor for reduced survival in childhood AML. Our findings shed light on the cytogenetic and mutational profile of childhood CK-AML and would inform refinement of risk stratification in childhood AML to improve outcomes.

Cytogenetic characteristics of and prognosis for acute myeloid leukemia in 107 children

Background Patients diagnosed with acute myeloid leukemia (AML) in childhood have a poor prognosis. A better understanding of prognostic factors will assist patients and clinicians in making difficult treatment decisions. Objectives To understand further the cytogenetic characteristics of and reassess the prognostic value of cytogenetic abnormalities in childhood AML. Methods Conventional karyotypes of 107 children with AML were analyzed retrospectively. The cases were divided into 4 groups based on genetic rearrangements; namely patients with: t(15;17)/PML-RARA; t(8;21)/RUNX1-RUNX1T1 or inv(16)(p13;q22) and t(16;16)/CBFB-MYH11; −7 or complex karyotypes; normal karyotypes or other cytogenetic changes. Differences in age, sex, leukocyte count, event-free survival (EFS), and overall survival (OS) were analyzed. Results All French-American-British (FAB) subtypes of AML were detected in 107 patients. We successfully cultured 81 of 107 bone marrow specimens, of which 60 cases had abnormal karyotypes. The most common abnormal karyotypes were t(8;21) (17/81 cases), followed by t(15;17) (13/81 cases), –X/Y (10/81 cases). There were no significant differences (P > 0.05) in age, sex, or leukocyte counts between the 4 groups. The differences in 3-year EFS and OS between each pair were significant, except for groups of patients with t(8;21)/RUNX1-RUNX1T1 and patients with normal karyotypes or other cytogenetic changes (P = 0.054). Conclusions Chromosomal abnormalities may provide important prognostic factors for AML in children and be helpful for risk stratification and individual treatment.

#23: Survival Analysis of Childhood Acute Myeloblastic Leukemia in a Limited Resource Center: Do Infection and Lymphocyte-Mediated Immune Response Play a Role?

Background Acute myeloblastic leukemia (AML) is the second most prevalent cancer among Indonesian children. In contrast to those of acute lymphoblastic leukemia (ALL), a number of studies reported unfavorable outcomes following the initiation of cytostatic protocols for childhood AML. In addition, our previous study showed that Gram-negative bacterial infection constitutes the major cause of treatment-related mortality in children with AML. These findings raised a question on the prognostic role of diagnostic lymphopenia, which represents the immunosuppressive state, as demonstrated in adult patients with solid tumors. Methods A retrospective cohort study, which involved children younger than 18 years of age with the newly diagnosed, non-M3 AML, was conducted. These children were admitted to Dr. Sardjito General Hospital, Yogyakarta, Indonesia, during the period of 2011–2019 and received National Pilot Protocol (2011–2016), Pediatric AML Protocol (2016–2018), and International Society of Pediatric Oncology (SIOP) Pediatric Oncology in Developing Countries (PODC) Protocol with prephase (2018–2019). One-year overall survival (OS) was analyzed, using diagnostic absolute lymphocyte counts (ALC0) of more than 4.5 × 109/L and less than 4.5 × 109/L as the determinants, in accordance with those reported in a number of studies on adult AML. Results Sixty-five children, which consisted of 41 (63%) children with ALC0 of more than 4.5 × 109/L and 24 (37%) children with ALC0 of less than 4.5 × 109/L, were eligible for this study. In a multivariate logistic regression analysis, compared with those of diagnostic white blood cell and peripheral blood myeloblast counts, treatment-related pneumonia, gastrointestinal tract infection, and sepsis were the most responsible factors for the occurrence of death within the first year of treatment [relative risk (RR), 2.82; 95% confidence interval (95% CI), 0.99–8.04; P = 0.05]. OS analysis showed that 43% and 16% of children with ALC0 of more than 4.5 × 109/L and less than 4.5 × 109/L, respectively, were alive within the first year of treatment. Cox-regression analysis, however, failed to reach statistical significance [hazard ratio (HR), 0.63; 95% CI, 0.33–1.18; P = 0.15]. Conclusion Despite lacked statistical significance, our study showed the superior one-year OS in children with ALC0 of more than 4.5 × 109/L. Our findings, therefore, might indicate the prognostic role of infection and lymphocyte-mediated immune response in childhood AML.

#8: Survival Analysis in Childhood Acute Myeloblastic Leukemia: Do Infection and Lymphocyte-Mediated Immune Response Play a Role?

Background Acute myeloblastic leukemia (AML) is the second most prevalent cancer among Indonesian children. In contrast, to those of acute lymphoblastic leukemia (ALL), a number of studies reported unfavorable outcomes following the initiation of cytostatic protocols for childhood AML. In addition, our previous study showed that Gram-negative bacterial infection constitutes the major cause of treatment-related mortality in children with AML. These findings raised a question on the prognostic role of diagnostic lymphopenia, which represents the immunosuppressive state, as demonstrated in adult patients with solid tumors. Methods A retrospective cohort study, which involved children younger than 18 years of age with the newly diagnosed, non-M3 AML, was conducted. These children were admitted to Dr. Sardjito General Hospital, Yogyakarta, Indonesia, during the period of 2011–2019 and received National Pilot Protocol (2011–2016), Pediatric AML Protocol (2016–2018), and International Society of Pediatric Oncology (SIOP) Pediatric Oncology in Developing Countries (PODC) Protocol with prephase (2018–2019). One-year overall survival (OS) was analyzed, using diagnostic absolute lymphocyte counts (ALC0) of more than 4.5 × 109/L and less than 4.5 × 109/L as the determinants, in accordance with those reported in a number of studies on adult AML. Results Sixty-five children, which consisted of 41 (63%) children with ALC0 of more than 4.5 × 109/L and 24 (37%) children with ALC0 of less than 4.5 × 109/L, were eligible for this study. Of these 65 children, 56 (86%) children received Cytosine arabinoside in the first week of treatment (National Pilot Protocol and Pediatric AML Protocol), while 9 (14%) children did not (SIOP PODC Protocol with prephase). OS analysis showed that 44% and 19% of children with ALC0 of more than 4.5 × 109/L and ALC0 of less than 4.5×109/L, respectively, were alive within the first year of treatment. Cox-regression analysis, however, failed to reach statistical significance [hazard ratio (HR), 0.63; 95% confidence interval (95% CI), 0.33–1.18; P = 0.15]. Conclusion Despite lacked statistical significance, our study showed the superior one-year OS in children with ALC0 of more than 4.5 × 109/L. Our findings, therefore, might indicate the prognostic role of infection and lymphocyte-mediated immune response in childhood AML.