Akio Tawa

Risk-Stratified Therapy and the Intensive Use of Cytarabine Improves the Outcome in Childhood Acute Myeloid Leukemia: The AML99 Trial From the Japanese Childhood AML Cooperative Study Group

PURPOSE To improve the prognosis in children with newly diagnosed acute myeloid leukemia (AML) by introducing a dose-dense intensive chemotherapy regimen and an appropriate risk stratification system. PATIENTS AND METHODS Two hundred forty children with de novo AML were treated with continuous cytarabine-based induction therapy and stratified to three risk groups based on the initial treatment response, age, and WBC at diagnosis and cytogenetics. All of the patients were treated with intensive consolidation chemotherapy including three or four courses of high-dose cytarabine. Allogeneic hematopoietic stem-cell transplantation (HSCT) was indicated for only the intermediate-risk patients with matched related donors and for all the high-risk subsets. RESULTS Two hundred twenty-seven children (94.6%) achieved a complete remission (CR). Four children demonstrated induction death. The median follow-up of the live patients was 55 months (range, 37 to 73 months). The 5-year overall survival of all 240 children was 75.6% (95% CI, 70.3% to 81.4%) and event-free survival was 61.6% (95% CI, 55.8% to 68.1%). The 5-year disease-free survival in each risk group were 71.3% (95% CI, 63.4% to 80.2%) in the low-risk group (n = 112), 59.8% (95% CI, 50.6% to 70.7%) in the intermediate-risk group (n = 92), and 56.5% (95% CI, 39.5% to 80.9%) in the high-risk group (n = 23). Eight children died during the first CR, including four after HSCT. CONCLUSION A high survival rate, 75.6% at 5 years, was achieved for childhood with de novo AML in the AML99 trial. The treatment strategy was well tolerated with only 1.7% induction death rate and 3.5% remission death rate. Low-risk children were successfully treated with chemotherapy alone.

Rearrangement of the T-Cell Receptor β-Chain Gene in Non-T-Cell, Non-B-Cell Acute Lymphoblastic Leukemia of Childhood

We studied 50 patients with childhood acute lymphoblastic leukemia (ALL), including 11 with T-cell ALL and 39 with non-T-cell, non-B-cell ALL. In addition to characterizing surface-antigen expression and immunoglobulin-gene rearrangement, we determined whether the T-cell receptor beta-chain gene also undergoes somatic rearrangement. All 11 patients with T-cell ALL had rearrangements of the beta-chain gene, with no persistence of the germline configuration. In two of these patients we demonstrated rearrangements of both the T-cell receptor gene and the immunoglobulin mu-heavy-chain gene. All 39 patients with non-T-cell, non-B-cell ALL had immunoglobulin heavy-chain gene rearrangements; in addition, 10 had rearrangements of the T-cell receptor beta-chain gene, indicating heterogeneity at the level of the T-cell receptor gene in this form of the disease. The results of our analysis of T-cell receptors and immunoglobulin heavy-chain genes offer new insight into normal and abnormal lymphocyte differentiation.

An Inv(16)(p13.3q24.3)-Encoded CBFA2T3-GLIS2 Fusion Protein Defines an Aggressive Subtype of Pediatric Acute Megakaryoblastic Leukemia

To define the mutation spectrum in non-Down syndrome acute megakaryoblastic leukemia (non-DS-AMKL), we performed transcriptome sequencing on diagnostic blasts from 14 pediatric patients and validated our findings in a recurrency/validation cohort consisting of 34 pediatric and 28 adult AMKL samples. Our analysis identified a cryptic chromosome 16 inversion (inv(16)(p13.3q24.3)) in 27% of pediatric cases, which encodes a CBFA2T3-GLIS2 fusion protein. Expression of CBFA2T3-GLIS2 in Drosophila and murine hematopoietic cells induced bone morphogenic protein (BMP) signaling and resulted in a marked increase in the self-renewal capacity of hematopoietic progenitors. These data suggest that expression of CBFA2T3-GLIS2 directly contributes to leukemogenesis.

Prospective Study of a Pirarubicin, Intermediate-Dose Cytarabine, and Etoposide Regimen in Children With Down Syndrome and Acute Myeloid Leukemia: The Japanese Childhood AML Cooperative Study Group

PURPOSE To evaluate a less intensive chemotherapeutic regimen specifically designed for patients with Down syndrome (DS) and acute myeloid leukemia (AML), and to determine the prognostic factors for event-free survival. PATIENTS AND METHODS Seventy-two patients with AML-DS were treated with remission induction chemotherapy consisting of pirarubicin (25 mg/m2/d for 2 days), cytarabine (100 mg/m2/d for 7 days), and etoposide (150 mg/m2/d for 3 days). Patients received four courses of intensification therapy of the same regimen. Prophylaxis for CNS leukemia was not included. RESULTS All but two patients were younger than 4 years, and 67 of the 72 patients (93%) were diagnosed as acute megakaryoblastic leukemia (AMKL). Seventy of the 72 patients (97.2%) achieved a complete remission (CR), and the estimated 4-year event-free survival (EFS) rate was 83% +/- 9%. Nine patients relapsed, and one died as a result of pneumonia during CR. Multivariate analysis revealed that the presence of monosomy 7 was a greater risk factor of adverse outcome (odds ratio = 5.67; P = .027). CONCLUSION A less intensive chemotherapeutic regimen produces excellent outcomes in standard-risk AML-DS patient. Risk-oriented therapy should be considered for future trials in AML-DS.

Extramedullary infiltration at diagnosis and prognosis in children with acute myelogenous leukemia

Extramedullary infiltration (EMI) is an occasional clinical symptom in childhood acute myelogenous leukemia (AML), but there is considerable controversy regarding the prognostic significance of EMI in AML.

Age-related changes in surface antigens on peripheral lymphocytes of healthy children.

The age‐related changes in proportion of various subsets within lymphocytes were investigated in cord blood and peripheral blood from healthy children and adults. The percentages of T and B cells did not show age‐related changes, whereas natural killer (NK) cells increased significantly with age. Within lymphocytes or the CD3+ T cell population the proportion of CD45RAbright+ lymphocytes decreased and that of CD45RO+ cells increased, while that of CD45RAdim+ cells showed no age‐related change. Within lymphocytes, the percentage of CD45RAbright+ CD4+ cells decreased, together with a decline of that of CD4+ cells. The proportions of CD45RAbright+ CD8+ cells and S6F1bright+ CD8+ cells increased with age, and the age‐dependent increase of the proportion of CD8+ cells seems to be mainly attributable to the increases in these subsets. The CD45RAdim+ CD4+ and CD45RAdim+ CD8+ cells co‐expressing CD45RO at a low level nevertheless showed no age‐related changes. In γδ T cells, both δTCS1+ and δTCS1‐ T cells increased with age, but the δTCS1‐γδ T cells increased more than the δCS1+ subset. Among lymphocytes, the percentages of CD20+, CD21+ and CD22+ cells remained similar, with no age‐related changes, but the proportion of CD5+ cells within lymphocytes or B cells decreased. The proportions of CD16+ NK cells among lymphocytes increased with age, and this change was attributable to the increase of CD56+ cells.

Mixed phenotype of blasts in acute megakaryocytic leukaemia and transient abnormal myelopoiesis in Down's syndrome

Blasts from eight cases with acute megakaryoblastic leukaemia (AMKL) and seven with transient abnormal myelopoiesis in Downs syndrome (TAM) were investigated to clarify their phenotypic characteristics. CD41 and CD7 were the most frequently expressed in both disorders. CD41 was positive in six TAM and five AMKL cases, and CD7 was positive in five TAM and five AMKL cases, respectively. CD33 was detected in four TAM and five AMKL cases. Other myeloid‐lineage associated antigens such as CD13 and CD11b could not be found in TAM but were expressed in five AMKL cases. Interestingly, CD56, a neural adhesion molecule, was expressed in three of four TAM and one of five AMKL cases. Cytoplasmic CD3 antigen was also noted in three of five examined cases.

Clinical significance of CD7-positive stem cell leukemia : a distinct subtype of mixed lineage leukemia

Ten leukemia cases with mixed phenotype were investigated in terms of clinical characteristics and cellular origin. Three patients were infants and six patients were older children. Six of them had a high leukocyte count and a mediastinal mass was found in three cases. All but one showed hepatosplenomegaly and/or lymphoadenopathy. In spite of intensive chemotherapy, most of them responded poorly. Cytochemical analysis of their leukemic cells revealed a low percentage of positivity for myeloperoxidase reactivity (< 25%) in two cases and electron microscopic platelet peroxidase reactivity was found in one of three analyzed cases. Phenotypically, these cells all expressed CD7, and other T‐lineage‐associated, B‐lineage‐associated, and/or myeloid‐associated antigens were also detected to some extent. In addition, three cases expressed CD41 and one case expressed CD56. The T‐cell receptor (TCR) genes and immunoglobulin gene were in the germline configuration in seven cases. In three rearranged cases two showed only the TCR‐δ gene rearrangement, and one had both TCR‐γ and δ gene rearrangements. Cell culture studies with 12–0‐tetradecanoyl‐phorbol‐13‐acetate (TPA) revealed differentiation to the T‐lineage in two cases and to a myeloid lineage in one case. Megakaryocytic differentiation was detected in two cases in culture without TPA. These results suggest that the cells from these cases arose from stem cells capable of both lymphoid and nonlymphoid differentiation. Although the cells were heterogeneous with regard to their potency of differentiation, they have similar clinical characteristics. Because of poor prognosis, it is important to identify this type of leukemia, and allogenic or autologous bone marrow transplantation should be considered. Cancer 68:2273–2280, 1991.

NUP98-NSD1 gene fusion and its related gene expression signature are strongly associated with a poor prognosis in pediatric acute myeloid leukemia.

The cryptic t(5;11)(q35;p15.5) creates a fusion gene between the NUP98 and NSD1 genes. To ascertain the significance of this gene fusion, we explored its frequency, clinical impact, and gene expression pattern using DNA microarray in pediatric acute myeloid leukemia (AML) patients. NUP98‐NSD1 fusion transcripts were detected in 6 (4.8%) of 124 pediatric AML patients. Supervised hierarchical clustering analyses using probe sets that were differentially expressed in these patients detected a characteristic gene expression pattern, including 18 NUP98‐NSD1‐negative patients (NUP98‐NSD1‐like patients). In total, a NUP98‐NSD1‐related gene expression signature (NUP98‐NSD1 signature) was found in 19% (24/124) and in 58% (15/26) of cytogenetically normal cases. Their 4‐year overall survival (OS) and event‐free survival (EFS) were poor (33.3% in NUP98‐NSD1‐positive and 38.9% in NUP98‐NSD1‐like patients) compared with 100 NUP98‐NSD1 signature‐negative patients (4‐year OS: 86.0%, 4‐year EFS: 72.0%). Interestingly, t(7;11)(p15;p15)/NUP98‐HOXA13, t(6;11)(q27;q23)/MLL‐MLLT4 and t(6;9)(p22;q34)/DEK‐NUP214, which are known as poor prognostic markers, were found in NUP98‐NSD1‐like patients. Furthermore, another type of NUP98‐NSD1 fusion transcript was identified by additional RT‐PCR analyses using other primers in a NUP98‐NSD1‐like patient, revealing the significance of this signature to detect NUP98‐NSD1 gene fusions and to identify a new poor prognostic subgroup in AML.

Tandem duplications of MLL and FLT3 are correlated with poor prognoses in pediatric acute myeloid leukemia: a study of the Japanese childhood AML Cooperative Study Group.

Mixed‐lineage leukemia (MLL)‐partial tandem duplication (PTD) is associated with poor prognosis in adult acute myeloid leukemia (AML), but its relationship to pediatric AML is unknown.