Development of Philadelphia chromosome-negative acute myeloid leukemia with IDH2 and NPM1 mutations in a patient with chronic myeloid leukemia who showed a major molecular response to tyrosine kinase inhibitor therapy.

Tyrosine kinase inhibitors (TKIs) are standard therapies for chronic myeloid leukemia (CML) that can eradicate Ph-positive leukemic cells. However, disease control is not achievable in a minority of cases, most commonly due to evolution of TKI-resistant clones. There have also been rare cases of emergence of Ph-negative clones with other cytogenetic abnormalities, and, less commonly, development of Ph-negative acute myeloid leukemia (AML), whose molecular pathogenesis is largely unknown. Here we report molecular features of a patient with Ph + CML who developed Ph-negative AML after showing a major molecular response to dasatinib. A 55-year-old man was diagnosed with CML. He achieved a complete cytogenetic response three months after dasatinib therapy but developed AML with normal karyotype 1 year later. After receiving induction and consolidation chemotherapy for AML, the patient achieved complete remission with no evidence of CML under maintenance with bosutinib. Targeted sequencing of serial bone marrow samples identified mutations in IDH2 and NPM1 in the Ph-negative AML cells, which had not been detected in CML cells. These results suggest that Ph-negative AML in this patient originated from a preleukemic population, which might have expanded during or after the successful elimination of CML clones with TKI therapy.

[Acquired hemophilia A requiring plasma exchange and mechanical ventilation].

A 56-year-old man who sustained a right waist injury 1 month ago, reported to our department complaining of pain in the right waist and femur for 1 day. In a computed tomography examination, hematoma of the right iliopsoas muscle was revealed, and arterial embolization was immediately performed but was not effective. Laboratory findings showed hemoglobin levels as 5.4 g/dl, platelet of 20.2×104/µl, prothrombine time of 13.1 s, partial thromboplastin time (APTT) of 81.1 s, and a convex upward curve of the APTT cross-mixing test. The activity of the coagulation factor VIII was <1.0%, but its amount was 120%, and the level of factor VIII inhibitor was 130 Bethesda Unit/ml. Disseminated intravascular coagulation was not noted. Under the diagnosis of acquired hemophilia A, treatment with prednisolone and recombinant activated factor VII was initiated. However, APTT remained prolonged, and intubation and mechanical ventilation were required because of right hemothorax. After steroid pulse therapy and plasma exchange, APTT returned to its normal range, and the inhibitor disappeared. Thus, we finally succeeded in extubation. This case indicated that intensive care may be necessary in the early phase treatment for acquired hemophilia A.

Chronic myelogenous leukemia in chronic phase transforming into acute leukemia under treatment with dasatinib 4 months after diagnosis.

We report a 64-year-old woman morphologically diagnosed with chronic myelogenous leukemia in the chronic phase. Despite having achieved a complete hematological response following treatment with dasatinib, she developed lymphoblastic crisis 4 months later. Blastic cells were in a CD45-negative and SSC-low fraction, and positive for CD10, CD19, CD34, and HLA-DR expression and rearrangement in the immunoglobulin heavy chain gene. Chemotherapy using the HyperCVAD/MA regimen led to a complete cytogenetic response, and after cord blood transplantation, she obtained a complete molecular remission. However, the crisis recurred 6 months later. Another salvage therapy using L-AdVP regimen followed by nilotinib led to a complete molecular remission. Retrospective analyses using flow cytometry and polymerase chain reaction revealed a minimal blastic crisis clone present in the initial marrow in chronic phase. This case is informative as it suggests that sudden blastic crisis may occur from an undetectable blastic clone present at initial diagnosis and that leukemic stem cells may survive cytotoxic chemotherapy that eliminates most of the blastic cells.

Expressional changes of genes and miRNA in common megakaryocyte-erythroid progenitors from lower-risk myelodysplastic syndrome.

Myelodysplastic syndrome (MDS) is a stem cell tumor characterized by dysplastic features and ineffective hematopoiesis in the early phase and leukemic progression in the late phase. Speculating that differences in the expression of genes and microRNA (miRNA) in control and MDS-derived erythroid progenitors may cause ineffective erythropoiesis, we sorted common megakaryocyte-erythroid progenitors (MEPs) in bone marrow cells from three lower-risk MDS patients, and compared expression levels of genes and miRNA with those from controls. In apoptosis-related pathways, the expression of some pro-apoptotic genes, such as cell death-inducing DFFA-like effector A, caspase 5, and Fas ligand, was elevated in MDS-derived MEPs, while those of anti-apoptotic CD40 and tumor necrosis factor were lower. In hematopoiesis-regulating pathways, RUNX1 and ETV6 genes showed reduced expression. Expression profiling revealed that three and 35 miRNAs were significantly up- and down-regulated in MDS-derived MEPs. MIR9 exhibited robust expression in MEPs and CD71+GlyA+ erythroid cells derived from one of the three patients. Interestingly, overexpression of MIR9 inhibited the accumulation of hemoglobin in UT-7/GM cells. Some of these alterations in gene and miRNA expression may contribute to the pathogenesis of ineffective hematopoiesis in lower-risk MDS and provide molecular markers for sub-classification and making a prognosis.

[Detection of BCR-ABL1 chimeric gene-positive neutrophils in a patient with mixed phenotype acute leukemia].

We experienced two patients with mixed phenotype acute leukemia with t(9;22)(q34;q11.2); BCR-ABL1 according to the WHO classification 2008. The type of BCR/ABL1 was major in both patients, and the chimeric gene was also detected in neutrophils from peripheral blood by the fluorescence in situ hybridization technique. Patient 1 was a 59-year-old Japanese woman, and patient 2 a 45-year-old Japanese man. They had both developed leukemia suddenly. Their leukemic blasts expressed B cell and myeloid cell antigens, but concomitantly in patient 1 (biphenotypic) and separately in patient 2 (biclonal). Percentages of BCR-ABL1-positive neutrophils were 98% and 89%, respectively. Both patients received an imatinib (600 mg/day)-combined Hyper-CVAD regimen as induction therapy, followed by treatment with dasatinib (140 mg/day). MEC therapy was also applied between these two treatments in patient 2. At present, patient 1 has obtained complete molecular remission quantitatively and qualitatively, and patient 2 only quantitatively. Considering their acute onsets with no prior history of chronic myelocytic leukemia (CML), they were both diagnosed as having acute leukemia with Ph1, but not blastic crisis of CML. In this tyrosine kinase inhibitor era, it has become more difficult to differentiate these two types of Ph1-positive leukemia development.