Toxicity and outcome of children with treatment related acute myeloid leukemia

Knockdown of ZFAS1 suppresses the progression of acute myeloid leukemia by regulating microRNA-150/Sp1 and microRNA-150/Myb pathways

Leukemia is the most frequent malignancy in children with acute myeloid leukemia (AML) as the second commonest type. Long non-coding RNA zinc finger antisense 1 (ZFAS1) has been widely reported as an oncogenic factor in multiple malignancies including AML. However, the roles and molecular mechanisms of ZFAS1 in the tumorigenesis of AML are poor defined till now. In the present study, RT-qPCR assay showed that ZFAS1 was highly expressed in bone marrow of acute leukemia patients and AML cell lines. Loss-of-function analyses revealed that ZFAS1 knockdown inhibited proliferation and promoted apoptosis in AML cells and curbed AML xenograft growth in vivo. Bioinformatics analysis and luciferase reporter assay unveiled that microRNA-150 (miR-150) could interact with ZFAS1, Myb 3' UTR and Sp1 3' UTR. Moreover, ZFAS1 acted as a molecular sponge of miR-150, giving rise to the downregulation of miR-150 level and upregulation of Myb and Sp1 levels. Moreover, miR-150 overexpression resulted in the reduction of AML cell proliferative ability and the increase of cell apoptotic rate. Additionally, the inhibition of miR-150 abrogated ZFAS1 loss-mediated anti-leukemia effects. In summary, our data demonstrated that ZFAS1 knockdown hampered AML progression by regulating miR-150/Myb and miR-150/Sp1 pathways, providing some potential biomarkers or targets for the diagnosis and treatment of leukemia.

How I treat myelodysplastic syndromes of childhood

Pediatric myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal disorders with an annual incidence of 1 to 4 cases per million, accounting for less than 5% of childhood hematologic malignancies. MDSs in children often occur in the context of inherited bone marrow failure syndromes, which represent a peculiarity of myelodysplasia diagnosed in pediatric patients. Moreover, germ line syndromes predisposing individuals to develop MDS or acute myeloid leukemia have recently been identified, such as those caused by mutations in GATA2, ETV6, SRP72, and SAMD9/SAMD9-L Refractory cytopenia of childhood (RCC) is the most frequent pediatric MDS variant, and it has specific histopathologic features. Allogeneic hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many children with MDSs and is routinely offered to all patients with MDS with excess of blasts, to those with MDS secondary to previously administered chemoradiotherapy, and to those with RCC associated with monosomy 7, complex karyotype, severe neutropenia, or transfusion dependence. Immune-suppressive therapy may be a treatment option for RCC patients with hypocellular bone marrow and the absence of monosomy 7 or a complex karyotype, although the response rate is lower than that observed in severe aplastic anemia, and a relevant proportion of these patients will subsequently need HSCT for either nonresponse or relapse.

Therapy-related Acute Myeloid Leukemia After the Treatment of Primary Solid Cancer in Children: A Single-center Experience

Therapy-related acute myeloid leukemia (t-AML) has a dismal prognosis and is one of the most frequent second malignant neoplasms which could be encountered by pediatric oncologists. Between October 2000 and September 2016, 16 patients who had primary solid tumors were diagnosed with t-AML at the Seoul National University Children's Hospital. The median patient age at the time of diagnosis of their primary solid tumors was 9.6 years (range, 0.1 to 15.4 y), and that of t-AML was 14.0 years (range, 4.7 to 23.9 y). The median latency period from the end of the primary tumor treatment to the initial diagnosis of t-AML was 29 months (range, 6 to 130 mo). Twelve patients achieved complete remission. Of them, only 7 patients underwent hematopoietic stem cell transplantation (HSCT). The 3-year overall survival (OS) rates and event-free survival rates were 33.7±12.2% and 26.9±11.5% respectively. The patients who underwent HSCT showed favorable 5-year OS rates (57.1±18.7%), whereas the 5-year OS rates of those who did not undergo HSCT was 0%. This study demonstrates that an achievement of complete remission and a subsequent HSCT can be the optimal solution for the treatment of t-AML, and this strategy showed acceptable outcomes.

Progress and Prospects in Pediatric Leukemia

Pediatric leukemia is the single most common malignancy affecting children, representing up to 30% of all pediatric cancers. Dramatic improvements in survival for acute lymphoblastic leukemia (ALL) have taken place over the past 4 decades with outcomes approaching 90% in the latest studies. However, progress has been slower for myeloid leukemia and certain subgroups like infant ALL, adolescent/young adult ALL, and relapsed ALL. Recent advances include recognition of molecularly defined subgroups, which has ushered in precision medicine approaches. We discuss the current understanding of the biology of the various childhood leukemias, recent advances in research, and future challenges in this field.

Cytogenetic abnormalities and monosomal karyotypes in children and adolescents with acute myeloid leukemia: correlations with clinical characteristics and outcome

The whole spectrum of chromosomal abnormalities and their prognostic significance in children and adolescents with acute myeloid leukemia (AML) has not been fully elucidated yet, although a considerable amount of knowledge has been gained recently. Moreover, the incidence and prognostic impact of monosomal karyotypes (MKs), which are new cytogenetic categories reported recently in adults with AML, are currently unknown for childhood and adolescent AML. In this study, we investigated the cytogenetic and clinical characteristics of 140 children and adolescents (≤21 y) with AML, and correlated their cytogenetic features with both the clinical characteristics and outcomes of our patient cohort. The most frequent cytogenetic abnormality found in our study was the t(15;17), followed by the t(8;21). Striking differences in the genetic abnormalities and French-American-British subtypes were found among infants, children, and adolescents. Of 124 cases, 15 (12.1%) met the criteria of the MK definition, and 12 of the 15 MKs (80%) were complex karyotypes. Of 124 cases, 27 (21.8%) had cytogenetic abnormalities sufficient to be diagnosed as AML with myelodyspastic sydrome-related features. As expected, patients with the t(15;17) had the most favorable outcomes, whereas patients with 11q23 rearrangements and monosomy 7 had the worst outcomes. These data expand our knowledge by providing novel insights into the cytogenetic features and their correlations with clinical characteristics and outcomes in childhood and adolescent AML.

Allogeneic hematopoietic stem cell transplantation for pediatric patients with treatment-related myelodysplastic syndrome or acute myelogenous leukemia

The development of treatment-related myelodysplastic syndrome (tMDS) or treatment-related acute myelogenous leukemia (tAML) is a complication that can occur after chemotherapy or radiation therapy. Eighteen patients with a previous malignancy treated at our institution and three patients with a nonmalignant primary tumor received an allogeneic hematopoietic stem cell transplant (HSCT) on the pediatric bone marrow (BM) transplantation service for the treatment of tMDS/tAML over a 15-year period. Five patients proceeded to HSCT without induction chemotherapy. Fourteen patients received high-dose cytarabine according to the Capizzi II regimen as first-line induction therapy with 13 of them achieving complete remission (CR) or refractory anemia (RA) with persistent cytogenetic abnormalities after this treatment. Two patients received an anthracycline-based induction therapy. Conditioning regimens were selected according to previous therapies: 11 patients received busulfan-melphalan-fludarabine (BU-MEL-FLU), which consisted of busulfan (0.8 mg/kg/dose every 6 hours ×10 doses), melphalan (70 mg/m(2)/dose × two doses), and fludarabine (25 mg/m(2)/dose × five doses) for cytoreduction; three patients received a total body irradiation (TBI)-containing regimen; seven patients received myeloablative regimens containing busulfan and/or melphalan and/or thiotepa with doses modified for organ toxicity. Sixteen patients received T cell-depleted (TCD) grafts; four patients received unmodified grafts; one patient received a double-unit cord blood transplantation (DUCBT). Donors included HLA-matched (n = 9), or mismatched (n = 3) related donors, or HLA-matched (n = 4), or mismatched (n = 4) unrelated donors, or DUCBT (n = 1). Disease status at the time of HSCT was: morphologic and cytogenetic CR (n = 12); RA with positive cytogenetics (n = 6); and refractory disease (n = 3). With a median follow-up of 5.9 years (2.2-15.7 years), the 5-year overall survival (OS) and disease-free survival (DFS) rates for the entire group were 61.1% with 12 patients alive without evidence of either primary disease or tMDS/tAML. The OS and DFS rate for the 11 patients who received the BU-MEL-FLU cytoreduction with TCD grafts was 54.5%. DFS was 65.7% for patients in RA or CR at HSCT compared with 0% for patients with >5% residual marrow blasts (P = .015). Nine patients died; the cause of death was relapse of MDS/AML (n = 4) or primary disease (n = 2), graft-versus-host disease (GVHD; n = 2), and infection (n = 1). Four patients developed grade II to IV acute GVHD. One patient developed localized chronic GVHD. Our results suggest that the strategy of induction with high-dose cytarabine therapy followed by allogeneic stem cell transplantation improves the overall outcome for patients with tMDS/tAML. In addition, the use of a TCD transplantation with BU-MEL-FLU as cytoreduction may decrease the toxicity of transplantation in heavily pretreated patients without an increase in relapse rate.