Keiko Yumura-Yagi

FBXW7 and NOTCH1 mutations in childhood T cell acute lymphoblastic leukaemia and T cell non-Hodgkin lymphoma

Mutation analysis of FBXW7 and NOTCH1 genes was performed in 55 T cell acute lymphoblastic leukaemia (T‐ALL) and 14 T cell non‐Hodgkin lymphoma (T‐NHL) patients who were treated on the Japan Association of Childhood Leukaemia Study (JACLS) protocols ALL‐97 and NHL‐98. FBXW7 and/or NOTCH1 mutations were found in 22 (40·0%) of 55 T‐ALL and 7 (50·0%) of 14 T‐NHL patients. FBXW7 mutations were found in 8 (14·6%) of 55 T‐ALL and 3 (21·4%) of 14 T‐NHL patients, and NOTCH1 mutations in 17 (30·9%) of 55 T‐ALL and 6 (42·9%) of 14 T‐NHL patients. Three (5·4%) T‐ALL and two (1·4%) T‐NHL patients had mutations in both FBXW7 and NOTCH1. FBXW7 mutations included one insertion, one deletion, one deletion/insertion and nine missense mutations. NOTCH1 mutations were detected in the heterodimerization domain (HD) in 15 cases, in the PEST domain in seven cases, and in both the HD and PEST domains in one case. Five‐year event‐free survival and overall survival for patients with FBXW7 and/or NOTCH1 mutations were 95·5% (95% CI, 71·9–99·4%) and 100% respectively, suggesting that T‐ALL patients with FBXW7 and/or NOTCH1 mutation represent a good prognosis compared to those without FBXW7 and/or NOTCH1 mutations (63·6%, P = 0·007 and 78·8%, P = 0·023, respectively).

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.

IKZF1 deletion is associated with a poor outcome in pediatric B-cell precursor acute lymphoblastic leukemia in Japan

Genetic alterations of Ikaros family zinc finger protein 1 (IKZF1), point mutations in Janus kinase 2 (JAK2), and overexpression of cytokine receptor‐like factor 2 (CRLF2) were recently reported to be associated with poor outcomes in pediatric B‐cell precursor (BCP)‐ALL. Herein, we conducted genetic analyses of IKZF1 deletion, point mutation of JAK2 exon 16, 17, and 21, CRLF2 expression, the presence of P2RY8‐CRLF2 fusion and F232C mutation in CRLF2 in 202 pediatric BCP‐ALL patients newly diagnosed and registered in Japan Childhood Leukemia Study ALL02 protocol to find out if alterations in these genes are determinants of poor outcome. All patients showed good response to initial prednisolone (PSL) treatment. Ph+, infantile, and Down syndrome–associated ALL were excluded. Deletion of IKZF1 occurred in 19/202 patients (9.4%) and CRLF2 overexpression occurred in 16/107 (15.0%), which are similar to previous reports. Patients with IKZF1 deletion had reduced event‐free survival (EFS) and overall survival (OS) compared to those in patients without IKZF1 deletion (5‐year EFS, 62.7% vs. 88.8%, 5‐year OS, 71.8% vs. 90.2%). Our data also showed significantly inferior 5‐year EFS (48.6% vs. 84.7%, log rank P = 0.0003) and 5‐year OS (62.3% vs. 85.4%, log rank P = 0.009) in NCI‐HR patients (n = 97). JAK2 mutations and P2RY8‐CRLF2 fusion were rarely detected. IKZF1 deletion was identified as adverse prognostic factor even in pediatric BCP‐ALL in NCI‐HR showing good response to PSL.

Outcome of childhood acute lymphoblastic leukemia with induction failure treated by the Japan Association of Childhood Leukemia study (JACLS) ALL F-protocol.

Children with acute lymphoblastic leukemia (ALL) who fail to achieve complete remission (CR) after induction therapy (induction failure: IF) have a poor prognosis; however, there have been few prospective studies in patients with IF.

Phenotypic Characteristics of Acute Megakaryocytic Leukemia and Transient Abnormal Myelopoiesis

By immunophenotyping and ultrastructural cytochemistry, the disorders involving megakaryocytic lineage cells have been clarified. These disorders are termed acute megakaryocytic leukemia (AMKL) and transient abnormal myelopoiesis (TAM). The characteristics of blasts in these disorders have been extensively investigated from various standpoints including cytochemistry, cytogenetics, ultrastructure and in vitro-colony differentiation. The target cells of AMKL and TAM are immature cells close to stem cells which are capable of differentiating into lineage cells such as megakaryocytes, erythrocytes and myeloid cells. Phenotypically, these blasts frequently express antigens appearing at an early stage in the hematopoietic differentiation pathway. They thus often emerge as mixed phenotypes as seen in mixed lineage leukemia of immature cell origin.

Increased expression of the multidrug-resistance gene in undifferentiated sarcoma

We analyzed multidrug‐resistance gene (mdr1 gene) expression in a patient with undifferentiated sarcoma of the liver using the cloned cDNA for the mdr1 gene. Tissue samples were available at the time of initial diagnosis and of two intracranial relapses after chemotherapy with a regimen including doxorubicin and teniposide. The level of mdr1 gene expression was increased sevenfold in the intracranial tumor at the time of first relapse and 11‐fold at the second relapse. This case may be an example of acquired multidrug resistance associated with overexpression of the mdr1 gene.

An overall characterization of pediatric acute lymphoblastic leukemia with CRLF2 overexpression

For an overall characterization of pediatric B‐cell precursor acute lymphoblastic leukemia (BCPALL) with CRLF2 overexpression (OE), we conducted genetic analysis of CRLF2 in 167 pediatric BCPALL patients. CRLF2 OE was detected in 30 (18%) of 167 patients, the P2RY8‐CRLF2 fusion was identified in only 3 (1.8%) of 167 patients, all of which demonstrated CRLF2 OE. Moreover, CRLF2 gain was identified in 18 (11%) of 167 patients. Messenger RNA sequencing revealed a novel fusion transcript, CSF2RA‐CRLF2, in a case with CRLF2 OE, suggesting that this fusion is associated with CRLF2 OE. In survival analysis, no significant differences in 5‐year event‐free survival (EFS) and overall survival were observed between patients with and without CRLF2 OE (70.7 vs. 75.4%, log rank P = 0.68 and 96.4 vs. 82.1%, log rank P = 0.11, respectively). However, a significant difference in 5‐year EFS between CRLF2 OE patients with and without IKZF1 deletion was observed (44.4 vs. 83.1%, log rank P = 0.02). In multivariate analysis, only IKZF1 deletion was a significant predictor of inferior OS (hazard ratio: 2.427, P = 0.04).These findings suggest that CRLF2 OE is not an independent prognostic factor in pediatric BCPALL.

Identification of novel kinase fusion transcripts in paediatric B cell precursor acute lymphoblastic leukaemia with IKZF1 deletion

Activating tyrosine kinase mutations or cytokine receptor signalling alterations have attracted attention as therapeutic targets for high‐risk paediatric acute lymphoblastic leukaemia (ALL). We identified two novel kinase fusions, OFD1‐JAK2 and NCOR1‐LYN, in paediatric ALL patients with IKZF1 deletion, by mRNA sequencing. The patient with CSF2RA‐CRLF2 also harboured IGH‐EPOR. All these patients had high‐risk features, such as high initial white blood cell counts and initial poor response to prednisolone. The functional analysis of these novel fusions is on‐going to determine whether these genetic alterations can be targeted by drugs.

Survival outcome after the first central nervous system relapse in children with acute lymphoblastic leukemia: a retrospective analysis of 79 patients in a joint program involving the experience of three Japanese study groups.

In a retrospective review of the survival outcome of children with isolated central nervous system (CNS) relapse of acute lymphoblastic leukemia (ALL), we identified 79 patients with CNS relapse among the eligible patients enrolled in ALL trials of 3 Japanese pediatric oncology study groups (Japanese Children’s Cancer and Leukemia Study Group [JCCLSG], Tokyo Children’s Cancer Study Group [TCCSG], and Japan Association of Childhood Leukemia Study [JACLS]) between 1989 and 1999. CNS relapses were diagnosed as the first adverse event between 1991 and 1999. The median age at the time of CNS relapse was 5.0 years (range, 0.7-15.1 years). The duration of the first remission ranged from 1.4 to 54 months (median, 12.4 months), and the observation period after CNS relapse ranged from 1 to 131 months (median, 27 months). Overall, 75 of the 79 patients achieved a second complete remission, 44 of whom had second relapses in the following sites: CNS, 18 patients; bone marrow, 15 patients; combined sites, 8 patients; and testis, 2 patients. Rates of overall survival and event-free survival at 4 years were 43.7% ± 5.8% (mean ± SE) and 32.9% ± 5.5%, respectively.The probability of remaining in second remission was significantly correlated with the leukocyte count (P = .005) and age (P = .02) at the initial diagnosis.