Clinical characteristics of Japanese patients with myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis.

Myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) is a rare disease, which presents with features of myelodysplastic syndromes with ring sideroblasts and essential thrombocythemia, as well as anemia and marked thrombocytosis. SF3B1 and JAK2 mutations are often found in patients, and are associated with their specific clinical features. This study was a retrospective analysis of 34 Japanese patients with MDS/MPN-RS-T. Median age at diagnosis was 77 (range, 51-88) years, and patients had anemia (median hemoglobin: 9.0 g/dL) and thrombocytosis (median platelet count: 642 × 109/L). Median overall survival was 70 (95% confidence interval: 68-not applicable) months during the median follow-up period of 26 (range: 0-91) months. A JAK2V617F mutation was detected in 46.2% (n = 12) of analyzed patients (n = 26), while an SF3B1 mutation was detected in 87.5% (n = 7) of analyzed patients (n = 8). Like those with myelodysplastic syndromes or myeloproliferative neoplasms, patients often received erythropoiesis-stimulating agents and aspirin to improve anemia and prevent thrombosis. This study, which was the largest to describe the real-world characteristics of Japanese patients with MDS/MPN-RS-T, showed that the patients had similar characteristics to those in western countries.

[Disseminated cryptococcosis during ibrutinib treatment for chronic lymphocytic leukemia].

We report a case of invasive fungal infection (IFI) that ensued during ibrutinib treatment. A 79-year-old female was diagnosed with chronic lymphocytic leukemia seven years prior. She had undergone chemotherapy at the ages of 72 and 75. Subsequently, she was placed on ibrutinib treatment at the age of 79. On the 119th day after the ibrutinib treatment initiation, she was admitted to our hospital with the complaints of frequent urination and hematuria, and three days later, she died of disseminated cryptococcosis.IFIs should be considered in the event of infections that develop early after the ibrutinib treatment initiation.

[Long-term administration of brentuximab vedotin in a patient with primary cutaneous anaplastic large cell lymphoma with peripheral blood involvement with leukemic change].

We report a case of long-term administration of brentuximab vedotin (BV) for primary cutaneous anaplastic large cell lymphoma (pc-ALCL) with leukemic change. A 67-year-old man with lymphadenopathy was admitted to our hospital. Six years ago, he was diagnosed with pc-ALCL at another hospital, and complete remission was achieved with radiation therapy. We performed a biopsy of his lymph node and diagnosed the recurrence of pc-ALCL with leukemic change. Initially, CHOP and GCD regimens were ineffective; however, partial remission was achieved following BV therapy. Thus far, he has received 42 courses of BV; he has responded well to the treatment and no serious side effects have been observed.

Aggressive TAFRO syndrome with reversible cardiomyopathy successfully treated with combination chemotherapy.

TAFRO (thrombocytopenia, anasarca, myelofibrosis, renal dysfunction, and organomegaly) syndrome is an atypical manifestation of Castleman's disease. However, the mechanism underlying this very rare syndrome remains unknown, and there is no established standard treatment. Here we report cases of two young females with TAFRO syndrome who showed similar clinical courses. Both cases showed severe anasarca, ascites, and thrombocytopenia. Although high-dose steroids were ineffective, combination chemotherapy showed remarkable effects. However, both patients developed severe but reversible heart failure after CHOP therapy owing to diffuse cardiomyopathy, which was presumably associated with TAFRO syndrome. Therefore, although combination chemotherapy may be very effective in the treatment of TAFRO syndrome, careful observation for cardiomyopathy development is needed, particularly when using adriamycin-containing regimens.

[Ischemic colitis following the treatment of acute hemorrhage in a patient with acquired hemophilia A].

A 66-year-old man with hypertension and hyperlipidemia developed a hemorrhagic stomal ulcer and massive hematoma of the face at 4 and 7 months, respectively, after fundusectomy for early gastric cancer. The diagnosis of acquired hemophilia A was made based on the marked prolongation of activated partial thromboplastin time, an extremely low factor VIII activity, and a very high-titer factor VIII inhibitor. After admission, oral prednisolone and cyclophosphamide were started. In addition, activated prothrombin complex concentrates and recombinant activated factor VII were intravenously administered which successfully controlled his hemorrhage. Only 1 week after the episode of bleeding, however, he complained of abdominal pain accompanied by watery stool with fresh blood. The diagnosis of ischemic colitis was made based on the clinical course and the findings on both CT-scan and colon fiberoscopy. The colitis spontaneously and quickly resolved with conservative observation. To the best of our knowledge, this is the first reported case of ischemic colitis that occurred in an acquired hemophilia patient without simultaneous administration of coagulation factors or antifibrinolytic agents. We should thus pay attention to the possible occurrence of thrombotic events even in acquired hemophilia patients in the presence of risk factors for thrombosis.

BCR/ABL activates Rap1 and B-Raf to stimulate the MEK/Erk signaling pathway in hematopoietic cells.

The BCR/ABL fusion tyrosine kinase activates various intracellular signaling pathways, thus causing chronic myeloid leukemia (CML). Here we demonstrate that the inducible expression of BCR/ABL in a murine hematopoietic cell line, TonB210, leads to the activation of the Ras family small GTPase Rap1, which is inhibited by the ABL kinase inhibitor imatinib. The Rap1 activity in a CML cell line, K562, was also inhibited by imatinib. Inhibition of Rap1 activation by a dominant negative mutant of Rap1, Rap1-N17, or SPA-1 inhibited the BCR/ABL-induced activation of Elk-1. BCR/ABL also activated in a kinase activity-dependent manner the B-Raf kinase, which is an effector molecule of Rap1 and a potent activator of the MEK/Erk/Elk-1 signaling pathway. Together, these data suggest that, in addition to the well-established Ras/Raf-1 pathway, BCR/ABL activates the alternative signaling pathway involving Rap1 and B-Raf to activate Erk, which may play important roles in leukemogenesis.

SDF-1 synergistically enhances IL-3-induced activation of the Raf-1/MEK/Erk signaling pathway through activation of Rac and its effector Pak kinases to promote hematopoiesis and chemotaxis.

Stromal cell-derived factor 1 (SDF-1) cooperates with cytokines to promote hematopoiesis. Here we demonstrate that SDF-1 activates Erk synergistically with interleukin-3 (IL-3) in hematopoietic cells. Small GTPases Ras and Rac were prominently activated by IL-3 and SDF-1, respectively. In accordance with this, Raf-1 was significantly activated by IL-3 but not by SDF-1. SDF-1 strongly induced phosphorylation of Raf-1 on S338, the target site for the Rac effector Paks, and enhanced the IL-3-induced activation of Raf-1 and MEK. Furthermore, the synergistic activation of Erk was inhibited by expression of a dominant-negative mutant of Pak1 or that of Rac and was enhanced by an activated mutant of Pak1. SDF-1 and IL-3 also showed synergistic effects on expansion of hematopoietic cells and on induction of chemotaxis, which were both inhibited by the MEK inhibitor PD98059. These results suggest that SDF-1 synergistically enhances IL-3-induced Erk activation by up-regulating Raf-1 activity through the Rac effector Pak kinases to promote hematopoiesis.

The two major imatinib resistance mutations E255K and T315I enhance the activity of BCR/ABL fusion kinase.

The resistance to the tyrosine kinase inhibitor imatinib in BCR/ABL-positive leukemias is mostly associated with mutations in the kinase domain of BCR/ABL, which include the most prevalent mutations E255K and T315I. Intriguingly, these mutations have also been identified in some patients before imatinib treatment. Here we examined the effects of these mutations on the kinase activity of a BCR/ABL kinase domain construct that also contained the SH3 and SH2 domains. When expressed in COS7 cells, the BCR/ABL construct with either E255K or T315I exhibited not only the resistance to imatinib but also the increase in activity to induce autophosphorylation as well as tyrosine phosphorylation of various cellular proteins, which included STAT5. The mutant kinases also showed increased activities in in vitro kinase assays. These results raise a possibility that the major imatinib resistance mutations E255K and T315I may confer the growth advantage on leukemic cells to expand in the absence of selective pressure from imatinib treatment.

[Late appearance of Philadelphia chromosome with the p190 BCR/ABL chimeric transcript in acute myelogenous leukemia progressing from myelodysplastic syndrome].

We report a late appearance of the Philadelphia chromosome (Ph) with the p190 BCR/ABL chimeric transcript in a 69-year-old patient with acute myelogenous leukemia (AML) that had evolved from myelodysplastic syndrome (MDS). In July 1997, the patient was found to have pancytopenia caused by refractory anemia with excess of blasts, which evolved into AML in 4 months. The leukemic cells were positive for CD13, CD14, CD33, and HLA-DR and had a normal karyotype. The patient achieved a complete remission after combination chemotherapy. However, his leukemia relapsed in November 1999, with the appearance of leukemic cells positive for CD7, CD13, CD34, and HLA-DR with a 46, XY, add (18) (p11) karyotype. The patient failed to achieve the second remission after several courses of intensive chemotherapy. When the number of blastic cells, showing the same surface phenotypes, in the peripheral blood increased drastically in April 2000, chromosomal analysis of leukemic cells revealed a 46, XY, t(9;22) (q34;q11), add(18)(p11) karyotype. The fusion of the BCR and ABL genes was confirmed by fluorescence in situ hybridization analysis, and the reverse transcription-polymerase chain reaction analysis further revealed the presence of the p190 BCR/ABL chimeric transcript. The appearance of the Ph chromosome in the course of MDS transforming to AML is very rare and may be correlated to the disease progression.

[A long-lasting idiopathic factor V inhibitor].

A rare case of a long-standing idiopathic acquired blood coagulation factor V (FV) inhibitor is reported. A 78 year-old male was admitted complaining of hematuria and tarry stools of two weeks' duration. He was noted to have a prolonged prothrombin time and activated partial thromboplastin time. A mixing study suggested the existence of an inhibitor and the activity of FV was less than 1%. Western blot analysis revealed the presence of anti-FV antibodies in the patient's serum. Because of significant bleeding tendencies, the patient received fresh-frozen plasma, platelet transfusions and methylprednisolone. His PT, APTT and FV activity were partially corrected although the disease was exacerbated when the steroid dose was tapered off. The patient was then treated with low dose cyclophosphamide. The majority of the cases with acquired FV inhibitor occur spontaneously in older patients but this condition may be associated with a surgical procedure, administration of antibiotics, tuberculosis or malignant diseases; some of them are, however, idiopathic. No underlying disease was detected in our present patient. The inhibitor disappears within 10 weeks in most patients and the prolonged presence of an idiopathic FV inhibitor is rare.

Activation of Rac and tyrosine phosphorylation of cytokine receptors induced by cross-linking of integrin alpha4beta1 and cell adhesion in hematopoietic cells.

Adhesion of hematopoietic cells, mainly through alpha4beta1 and alpha5beta1 integrins, to the bone marrow microenvironment may play important roles in regulation of hematopoiesis. However, the mechanisms for signaling, outside-in signaling, have largely remained to be established. We demonstrate here that cross-linking of alpha4beta1 by anti-alpha4 antibody induces tyrosine phosphorylation of Pyk2, Shc, and Cbl as well as binding of the adaptor protein CrkL with Cbl in a murine hematopoietic cell line, 32D/EpoR-Wt. Furthermore, cross-linking of alpha4beta1 induced activation of the Rho family small GTPase Rac, which was enhanced by induced overexpression of CrkL and was inhibited by the phosphatidylinositol 3(')-kinase (PI3K) inhibitor LY294002. In addition, adhesion of 32D/EpoR-Wt cells to immobilized H-296, a recombinant fibronectin peptide specific for alpha4beta1, induced tyrosine phosphorylation of Jak2, the erythropoietin receptor (EpoR), and the IL-3 receptor beta subunit as well as Pyk2, Shc, and Cbl. Tyrosine phosphorylation of Jak2 and EpoR was also induced in a human leukemic cell line, UT-7, by adhesion to immobilized H-296. However, adhesion of 32D/EpoR-PM4 cells, expressing the W282R mutant EpoR defective in coupling with Jak2, to immobilized H-296 failed to induce tyrosine phosphorylation of the mutant EpoR. These results implicate CrkL in PI3K-dependent activation of Rac by outside-in signaling from alpha4beta1 and suggest that adhesion through alpha4beta1 further activates cytokine receptor-associated Jak2 to induce phosphorylation of these receptors.

[Hypercalcemia mediated by parathyroid hormone-related protein in the blastic phase of chronic myelogenous leukemia].

A 45-year-old man with chronic myelogenous leukemia (CML) in the accelerated phase was admitted to our hospital because of lower back pain and hypercalcemia. On admission, he was confused and found to have massive splenomegaly. The hypercalcemia and splenomegaly improved significantly after administration of incadronate, hydroxyurea, vincristine and prednisolone. Splenomegaly recurred after cessation of the chemotherapy, and examination of the peripheral blood showed 31% blasts, positive for both CD13 and CD33, on which basis myeloid blastic transformation was diagnosed. Vindesine, cytarabine and prednisolone were administered, and the splenomegaly improved again. On admission, when the patient's serum calcium level was 16.0 mg/dl, his serum parathyroid hormone-related protein (PTHrP) level was elevated to 118.3 pmol/l. Furthermore, RT-PCR analysis revealed that the patient's CML cells expressed PTHrP mRNA, and a high level of PTHrP was detected in the supernatant of cultured mononuclear cells derived from the patient's peripheral blood. These findings indicated that the hypercalcemia was due to production of PTHrP by the leukemic cells. Several cases of PTHrP. mediated hypercalcemia associated with CML have been reported previously, and are reviewed here.