BTK, NUTM2A, and PRPF19 Are Novel KMT2A Partner Genes in Childhood Acute Leukemia

Chromosomal rearrangements of the human KMT2A/MLL gene are associated with acute leukemias, especially in infants. KMT2A is rearranged with a big variety of partner genes and in multiple breakpoint locations. Detection of all types of KMT2A rearrangements is an essential part of acute leukemia initial diagnostics and follow-up, as it has a strong impact on the patients’ outcome. Due to their high heterogeneity, KMT2A rearrangements are most effectively uncovered by next-generation sequencing (NGS), which, however, requires a thorough prescreening by cytogenetics. Here, we aimed to characterize uncommon KMT2A rearrangements in childhood acute leukemia by conventional karyotyping, FISH, and targeted NGS on both DNA and RNA level with subsequent validation. As a result of this comprehensive approach, three novel KMT2A rearrangements were discovered: ins(X;11)(q26;q13q25)/KMT2A-BTK, t(10;11)(q22;q23.3)/KMT2A-NUTM2A, and inv(11)(q12.2q23.3)/KMT2A-PRPF19. These novel KMT2A-chimeric genes expand our knowledge of the mechanisms of KMT2A-associated leukemogenesis and allow tracing the dynamics of minimal residual disease in the given patients.

Expression of NK Cell Receptor Ligands on Leukemic Cells Is Associated with the Outcome of Childhood Acute Leukemia

Acute leukemia is the most common malignancy in children. Most patients are cured, but refractory/relapsed AML and ALL are the first cause of death from malignancy in children. Maintenance chemotherapy in ALL has improved survival by inducing leukemic cell apoptosis, but immune surveillance effectors such as NK cells might also contribute. The outcome of B-ALL (n = 70), T-ALL (n = 16), and AML (n = 16) pediatric patients was evaluated according to leukemic cell expression of ligands for activating and inhibiting receptors that regulate NK cell functioning. Increased expression of ULBP-1, a ligand for NKG2D, but not that of CD112 or CD155, ligands for DNAM-1, was associated with poorer 5-year event-free survival (5y-EFS, 77.6% vs. 94.9%, p < 0.03). Reduced expression of HLA-C on leukemic cells in patients with the KIR2DL1/HLA-C*04 interaction was associated with a higher rate of relapse (17.6% vs. 4.4%, p = 0.035) and lower 5y-EFS (70.6% vs. 92.6%, p < 0.002). KIR2DL1/HLA-C*04 interaction was an independent predictive factor of events (HR = 4.795, p < 0.005) or death (HR = 6.731, p < 0.005) and might provide additional information to the current risk stratification. Children who carry the KIR2DL1/HLA-C*04 interaction were refractory to current chemotherapy treatments, including allogeneic stem cell transplantation; therefore, they should be considered as candidates for alternative biological therapies that might offer better results.

The Association of Insulin-Like Growth Factor-1 With Bone Mineral Density in Survivors of Childhood Acute Leukemia

Background: The purpose of the current study is to investigate bone mineral deficit of children in survivors of childhood acute leukemia and examine the association of insulin-like growth factor-1 (IGF-1) with bone mineral density (BMD) status and the presence of osteoporosis. Methods: In a cross-sectional study of children diagnosed with different types of acute leukemia at age between 6 months and 18 years, serum IGF-1 and IGFBP-3, were assessed in relation to lumbar spine BMD (LSBMD) by using dual-energy x-ray absorptiometry and non-traumatic vertebral fracture by lateral thoracolumbar spine radiographs. Standard deviation scores (SDS) were calculated based on the age- and gender-adjusted population mean. Results: Among 189 children after completion of acute leukemia treatment, 22 (11.6%) children had LSBMD SDS less than -2.0 while 80 (42.3 %) children were diagnosed with osteoporosis. Mean areal BMD and LSBMD SDS of the subjects were 0.862±0.197 g/cm2 and -0.6±1.6, respectively. IGF-1 and IGFBP-3 were lower in children with LSBMD lower than -2.0 (P&lt;0.05) and those with osteoporosis (P&lt;0.05). LSBMD SDS showed linear correlation with serum IGF-1 (P=0.041). Low serum IGF-1 level (OR=0.724, P=0.042) and elder age of leukemia diagnosis (OR=1.089, P=0.023) were suggested risk factor of the occurrence of osteoporosis. Conclusions: Substantial number of survivors from childhood acute leukemia undergo bone mineral deficits, and serum IGF-1 status could be a prognostic factor associated with bone mass acquisition and future occurrence of osteoporosis.

Acute Myelogenous Leukemia Associated with MLL-SEPT6 Rearrangement and TRAF3, FGFR3 Mutation: A Pediatric Case Report and Review of the Literature

The MLL gene is a site of frequent rearrangement in acute leukemia with multiple fusion partners, but MLL-SEPT6 rearrangement is rare in clinical leukemia practice, and only 13 cases have been reported. We describe the case of an acute myelogenous leukemia child with MLL-SEPT6 rearrangement whose age of onset and accompanying gene mutations differs from previous reports. Considering the poor prognosis of leukemia children with MLL-SEPT6 rearrangement and the unsatisfactory results of existing treatments, the study of this case may provide new theories for diagnosis and treatment of MLL-SEPT6-associated childhood acute leukemia.

Profile of PD-L1 mRNA Expression in Childhood Acute Leukemia

Background: Programmed Death Ligand 1 (PD-L1) expression was used to determine type of patients who respond to immunotherapy using immune checkpoint inhibitor in several solid malignancies. However, the role of PD-L1 in hematological malignancies is less explored. Therefore, we aim to investigate PD-L1 mRNA expression in childhood leukemia patients. Association between PD-L1 expression and clinicopathological features was also analyzed. Method: Blood samples of 17 childhood leukemia patients and 12 healthy individuals as control were used in this study. The samples were collected in Dharmais Cancer Hospital. Real time PCR was used to analyze PD-L1 expression with GAPDH as internal control. Result: PD-L1 mRNA expression is significantly lower in childhood leukemia patients (medians: 0.0012) compared to healthy individuals (medians: 0.0041) (p=0.017). PD-L1 mRNA expressions were not correlated with age (p=1.000), sex (p=1.000), outcome (p=1.000), type of leukemia (p=1.000), hyperleukocytosis (p=1.000), and syndrome down (p=0.426). Conclusion: PD-L1 expression is lower in leukemia patients compared to healthy controls. PD-L1 expressions were not correlated with all clinicopathological features. Our result provides preliminary data of PD-L1 expression in Indonesian childhood leukemia patients.