Fumiko Kosaka

Mutations of the epigenetics-modifying gene (DNMT3a, TET2, IDH1/2) at diagnosis may induce FLT3-ITD at relapse in de novo acute myeloid leukemia.

Gene mutations were found in acute myeloid leukemia (AML) and their importance has been noted. To clarify the importance and stability of mutations, we examined gene mutations in paired samples at diagnosis and relapse of 34 adult AML patients. Five acquired gene mutations were detected at relapse. Of the 45 gene mutations at diagnosis, 11 of them were lost at relapse. The acquired mutations at relapse were all class I mutations as Fms-like tyrosine kinase 3 (FLT3) and rat sarcoma viral oncogene homolog (RAS) mutations. The disappeared mutations at relapse were 3 of 11 internal tandem duplications of FLT3 (FLT3-ITD) (27.3%), 3 of 3 FLT3 tyrosine kinase domain (FLT3-TKD) (100%), 3 of 13 Nucleophosmin 1 (23.1%) and 2 of 5 CCAAT/enhancer-binding protein-α (40%) mutations. However, epigenetics-modifying gene (DNMT3a, TET2 and IDH1/2) mutations had no change between diagnosis and relapse samples, and may become minimal residual disease marker. The frequency of FLT3-ITD at relapse in patients with DNMT3a mutation at diagnosis is significantly higher than those in patients without them (P=0.001). Moreover, the high frequency of FLT3-ITD at relapse is also seen in AML cases that initially present with any epigenetics-modifying gene mutations (P<0.001). Our results indicate that epigenetics-modifying gene mutations may cause genetic instability and induce FLT3-ITD, leading to resistance to therapy and relapse.

Polycythemia associated with the JAK2V617F mutation emerged during treatment of chronic myelogenous leukemia

Polycythemia associated with the JAK2V617F mutation emerged during treatment of chronic myelogenous leukemia

Importance of c-kit mutation detection method sensitivity in prognostic analyses of t(8;21)(q22;q22) acute myeloid leukemia

Recently, c-kit mutations have been reported as a novel adverse prognostic factor of acute myeloid leukemia with t(8;21)(q22;q22) translocation (t(8;21) AML). However, much remains unclear about its clinical significance. In this study, we developed a highly sensitive mutation detection method known as mutation-biased PCR (MB-PCR) and investigated the relationship between c-kit mutations and prognosis. When c-kit mutations were analyzed for 26 cases of t(8;21) AML using the direct sequence (DS) and MB-PCR, the latter had a much higher detection rate of c-kit mutations at initial presentation (DS 5/26(19.2%) vs MB-PCR 12/26(46.2%)). Interestingly for the three cases, in which c-kit mutations were observed only at relapse with the DS, c-kit mutations were detected at initial presentation using the MB-PCR. This result suggests that a minor leukemia clone with c-kit mutations have resistance to treatment and are involved in relapse. In univariate analyses, the presence of a c-kit mutation using DS was not an adverse prognostic factor (P=0.355), but was a factor when using MB-PCR (P=0.014). The presence of c-kit mutations with MB-PCR was also an independent adverse prognostic factor by multivariate analyses (P=0.006). We conclude that sensitivity of c-kit mutation detection method is important to predict prognosis for t(8;21) AML.

Identification and functional characterization of novel telomerase variant alleles in Japanese patients with bone-marrow failure syndromes.

As the incidence of bone-marrow failure syndromes (BMFS) is 2-3x higher in East Asia than in the West, we examined peripheral blood or marrow cells of 100 Japanese patients for possible pathogenic mutations in the two main components of the telomere-synthesizing enzyme telomerase (hTERC RNA and hTERT protein) that have recently been implicated in the disease pathogenesis. We analyzed samples collected from 34 patients with acquired aplastic anemia (AA), 66 patients with myelodysplastic syndromes (MDS) and 120 healthy controls. In addition to two polymorphic germ-line sequence changes (n-771A/G and n-714 C insertion) in the promoter region of hTERC and eleven hTERT polymorphisms that were identified in both patients and healthy individuals, we found a novel germ-line C323T mutation in the hTERC RNA in an MDS patient only. This heterozygous C323T mutation abolished telomerase enzymatic activity and functioned in a haploinsufficiency manner to modulate telomerase activity in cells. In summary, this study reports a novel telomerase natural variant that abolishes telomerase function, which may lead to telomere shortening and marrow hypocellularity in patients with BMFS. This study also highlights the rarity of genetic alterations in BMFS patients in Japan, which suggests that other factors may play a more prominent role in the disease pathogenesis in East Asia.

Complex molecular genetic abnormalities involving three or more genetic mutations are important prognostic factors for acute myeloid leukemia

We conducted a comprehensive analysis of 28 recurrently mutated genes in acute myeloid leukemia (AML) in 271 patients with de novo AML. Co-mutations were frequently detected in the intermediate cytogenetic risk group, at an average of 2.76 co-mutations per patient. When assessing the prognostic impact of these co-mutations in the intermediate cytogenetic risk group, overall survival (OS) was found to be significantly shorter (P=0.0006) and cumulative incidence of relapse (CIR) significantly higher (P=0.0052) in patients with complex molecular genetic abnormalities (CMGAs) involving three or more mutations. This trend was marked even among patients aged ⩽65 years who were also FLT3-ITD (FMS-like tyrosine kinase 3 internal tandem duplications)-negative (OS: P=0.0010; CIR: P=0.1800). Moreover, the multivariate analysis revealed that CMGA positivity was an independent prognostic factor associated with OS (P=0.0007). In stratification based on FLT3-ITD and CEBPA status and ‘simplified analysis of co-mutations’ using seven genes that featured frequently in CMGAs, CMGA positivity retained its prognostic value in transplantation-aged patients of the intermediate cytogenetic risk group (OS: P=0.0002. CIR: P<0.0001). In conclusion, CMGAs in AML were found to be strong independent adverse prognostic factors and simplified co-mutation analysis to have clinical usefulness and applicability.

Analysis of the exon 12 and 14 mutations of the JAK2 gene in Philadelphia chromosome-positive leukemia.

Analysis of the exon 12 and 14 mutations of the JAK 2 gene in Philadelphia chromosome-positive leukemia

Clinical features of Japanese polycythemia vera and essential thrombocythemia patients harboring CALR, JAK2V617F, JAK2Ex12del, and MPLW515L/K mutations.

The risk of complication of polycythemia vera (PV) and essential thrombocythemia (ET) by thrombosis in Japanese patients is clearly lower than in western populations, suggesting that genetic background such as race may influence the clinical features. This study aimed to clarify the relationship between genetic mutations and haplotypes and clinical features in Japanese patients with PV and ET. Clinical features were assessed prospectively among 74 PV and 303 ET patients. There were no clinical differences, including JAK2V617F allele burden, between PV patients harboring the various genetic mutations. However, CALR mutation-positive ET patients had a significantly lower WBC count, Hb value, Ht value, and neutrophil alkaline phosphatase score (NAP), and significantly more platelets, relative to JAK2V617F-positive ET patients and ET patients with no mutations. Compared to normal controls, the frequency of the JAK246/1 haplotype was significantly higher among patients with JAK2V617F, JAK2Ex12del, or MPL mutations, whereas no significant difference was found among CALR mutation-positive patients. CALR mutation-positive patients had a lower incidence of thrombosis relative to JAK2V617F-positive patients. Our findings suggest that JAK2V617F-positive ET patients and CALR mutation-positive patients have different mechanisms of occurrence and clinical features of ET, suggesting the potential need for therapy stratification in the future.

Clinical characteristics and prognosis of acute myeloid leukemia associated with DNA-methylation regulatory gene mutations.

In recent years, it has been reported that the frequency of DNA-methylation regulatory gene mutations – mutations of the genes that regulate gene expression through DNA methylation – is high in acute myeloid leukemia. The objective of the present study was to elucidate the clinical characteristics and prognosis of acute myeloid leukemia with associated DNA-methylation regulatory gene mutation. We studied 308 patients with acute myeloid leukemia. DNA-methylation regulatory gene mutations were observed in 135 of the 308 cases (43.8%). Acute myeloid leukemia associated with a DNA-methylation regulatory gene mutation was more frequent in older patients (P<0.0001) and in patients with intermediate cytogenetic risk (P<0.0001) accompanied by a high white blood cell count (P=0.0032). DNA-methylation regulatory gene mutation was an unfavorable prognostic factor for overall survival in the whole cohort (P=0.0018), in patients aged ≤70 years, in patients with intermediate cytogenetic risk, and in FLT3-ITD-negative patients (P=0.0409). Among the patients with DNA-methylation regulatory gene mutations, 26.7% were found to have two or more such mutations and prognosis worsened with increasing number of mutations. In multivariate analysis DNA-methylation regulatory gene mutation was an independent unfavorable prognostic factor for overall survival (P=0.0424). However, patients with a DNA-methylation regulatory gene mutation who underwent allogeneic stem cell transplantation in first remission had a significantly better prognosis than those who did not undergo such transplantation (P=0.0254). Our study establishes that DNA-methylation regulatory gene mutation is an important unfavorable prognostic factor in acute myeloid leukemia.

Identification of TINF2 gene mutations in adult Japanese patients with acquired bone marrow failure syndromes.

Haematologica, 118, 27–29. Finnegan, D.P., Kettle, P., Drake, M., Matthews, C., Alexander, H.D., Popat, R., Cavanagh, J.D., Wachsman, W. & Morris, T. (2006) Bortezomib is effective in primary plasma cell leukemia. Leukaemia & Lymphoma, 47, 1670–1673. Garcia-Sanz, R., Orfao, A., Gonzalez, M., Tabernero, M.D., Blade, J., Moro, M.J., Fernandez-Calvo, J., Sanz, M.A., PerezSimon, J.A., Rasillo, A. & Miguel, J.F. (1999) Primary plasma cell leukemia: clinical, immunophenotypic, DNA ploidy, and cytogenetic characteristics. Blood, 93, 1032–1037. Gemmel, C., Cremer, F.W., Weis, M., Witzens, M., Moldenhauer, G., Koniczek, K.H., Imbach, U., Ho, A.D., Moos, M. & Goldschmidt, H. (2002) Anti-CD20 antibody as consolidation therapy in a patient with primary plasma cell leukemia after high-dose therapy and autologous stem cell transplantation. Annals of Hematology, 81, 119–123. Oka, S., Yokote, T., Akioka, T., Hara, S., Yamano, T., Tsuji, M. & Hanafusa, T. (2006) Successful treatment of multi-agent chemotherapy with rituximab for IgM plasma cell leukemia. Leukemia Research, 30, 1581–1583. RuizArguelles, G.J. & San Miguel, J.F. (1994) Cell surface markers in multiple myeloma. Mayo Clinic Proceedings, 69, 684–690. Saccaro, S., Fonseca, R., Veillon, D.M., Cotelingam, J., Nordberg, M.L., Bredeson, C., Glass, J. & Munker, R. (2005) Primary plasma cell leukemia: report of 17 new cases treated with autologous or allogeneic stem-cell transplantation and review of the literature. American Journal of Hematology, 78, 288–294. Tanioka, F., Tamashima, S., Shimizu, S., Kobayashi, H., Kobayashi, Y. & Sugimura, H. (2003) A case of primary plasma cell leukemia with hairycell morphology and k -type Bence-Jones protein. Immunohistochemical and molecular analysis. Japanese Journal of Clinical Oncology, 33, 232–237. Walters, M., Olteanu, H., Van Tuinen, P. & Kroft, S.H. (2010) CD23 expression in plasma cell myeloma is specific for abnormalities of chromosome 11, and is associated with primary plasma cell leukaemia in this cytogenetic sub-group. British Journal of Haematology, 149, 292–293.

correspondence: Identification of TINF2 gene mutations in adult Japanese patients with acquired bone marrow failure syndromes

Haematologica, 118, 27–29. Finnegan, D.P., Kettle, P., Drake, M., Matthews, C., Alexander, H.D., Popat, R., Cavanagh, J.D., Wachsman, W. & Morris, T. (2006) Bortezomib is effective in primary plasma cell leukemia. Leukaemia & Lymphoma, 47, 1670–1673. Garcia-Sanz, R., Orfao, A., Gonzalez, M., Tabernero, M.D., Blade, J., Moro, M.J., Fernandez-Calvo, J., Sanz, M.A., PerezSimon, J.A., Rasillo, A. & Miguel, J.F. (1999) Primary plasma cell leukemia: clinical, immunophenotypic, DNA ploidy, and cytogenetic characteristics. Blood, 93, 1032–1037. Gemmel, C., Cremer, F.W., Weis, M., Witzens, M., Moldenhauer, G., Koniczek, K.H., Imbach, U., Ho, A.D., Moos, M. & Goldschmidt, H. (2002) Anti-CD20 antibody as consolidation therapy in a patient with primary plasma cell leukemia after high-dose therapy and autologous stem cell transplantation. Annals of Hematology, 81, 119–123. Oka, S., Yokote, T., Akioka, T., Hara, S., Yamano, T., Tsuji, M. & Hanafusa, T. (2006) Successful treatment of multi-agent chemotherapy with rituximab for IgM plasma cell leukemia. Leukemia Research, 30, 1581–1583. RuizArguelles, G.J. & San Miguel, J.F. (1994) Cell surface markers in multiple myeloma. Mayo Clinic Proceedings, 69, 684–690. Saccaro, S., Fonseca, R., Veillon, D.M., Cotelingam, J., Nordberg, M.L., Bredeson, C., Glass, J. & Munker, R. (2005) Primary plasma cell leukemia: report of 17 new cases treated with autologous or allogeneic stem-cell transplantation and review of the literature. American Journal of Hematology, 78, 288–294. Tanioka, F., Tamashima, S., Shimizu, S., Kobayashi, H., Kobayashi, Y. & Sugimura, H. (2003) A case of primary plasma cell leukemia with hairycell morphology and k -type Bence-Jones protein. Immunohistochemical and molecular analysis. Japanese Journal of Clinical Oncology, 33, 232–237. Walters, M., Olteanu, H., Van Tuinen, P. & Kroft, S.H. (2010) CD23 expression in plasma cell myeloma is specific for abnormalities of chromosome 11, and is associated with primary plasma cell leukaemia in this cytogenetic sub-group. British Journal of Haematology, 149, 292–293.