Identification of putative noncanonical driver mutations in patients with essential thrombocythemia.

Essential thrombocythemia (ET) cases without canonical JAK2, CALR, or MPL mutations, that is, triple-negative (TN) ET, have been found in 10%-20% of ET cases. Owing to the limited number of TN ET cases, its clinical significance remains unclear. This study evaluated TN ET's clinical characteristics and identified novel driver mutations. Among 119 patients with ET, 20 (16.8%) had no canonical JAK2/CALR/MPL mutations. Patients with TN ET tended to be younger and had lower white blood cell counts and lactate dehydrogenase values. We identified putative driver mutations in 7 (35%): MPL S204P, MPL L265F, JAK2 R683G, and JAK2 T875N were previously reported as candidate driver mutations in ET. Moreover, we identified a THPO splicing site mutation, MPL*636Wext*12, and MPL E237K. Four of the seven identified driver mutations were germline. Functional studies on MPL*636Wext*12 and MPL E237K revealed that they are gain-of-function mutants that increase MPL signaling and confer thrombopoietin hypersensitivity with very low efficiency. Patients with TN ET tended to be younger, although this was thought to be due to the inclusion of germline mutations, hereditary thrombocytosis. Accumulating the genetic and clinical characteristics of noncanonical mutations may help future clinical interventions in TN ET and hereditary thrombocytosis.

Tyrosine kinase inhibitors induce alternative spliced BCR-ABLIns35bp variant via inhibition of RNA polymerase II on genomic BCR-ABL.

To elucidate dynamic changes in native BCR-ABL and alternatively spliced tyrosine kinase inhibitor (TKI)-resistant but function-dead BCR-ABLIns35bp variant, following commencement or discontinuation of TKI therapy, each transcript was serially quantified in patients with chronic myeloid leukemia (CML) by deep sequencing. Because both transcripts were amplified together using conventional PCR system for measuring International Scale (IS), deep sequencing method was used for quantifying such BCR-ABL variants. At the initial diagnosis, 7 of 9 patients presented a small fraction of cells possessing BCR-ABLIns35bp , accounting for 0.8% of the total IS BCR-ABL, corresponding to actual BCR-ABLIns35bp value of 1.1539% IS. TKI rapidly decreased native BCR-ABL but not BCR-ABLIns35bp , leading to the initial increase in the proportion of BCR-ABLIns35bp . Thereafter, both native BCR-ABL and BCR-ABLIns35bp gradually decreased in the course of TKI treatment, whereas small populations positive for TKI-resistant BCR-ABLIns35bp continued fluctuating at low levels, possibly underestimating the molecular response (MR). Following TKI discontinuation, sequencing analysis of 54 patients revealed a rapid relapse, apparently derived from native BCR-ABL+ clones. However, IS fluctuating at low levels around MR4.0 marked a predominant persistence of cells expressing function-dead BCR-ABLIns35bp , suggesting that TKI resumption was unnecessary. We clarified the possible mechanism underlying mis-splicing BCR-ABLIns35bp , occurring at the particular pseudo-splice site within intron8, which can be augmented by TKI treatment through inhibition of RNA polymerase II phosphorylation. No mutations were found in spliceosomal genes. Therefore, monitoring IS functional BCR-ABL extracting BCR-ABLIns35bp would lead us to a correct evaluation of MR status, thus determining the adequate therapeutic intervention.

Successful allogeneic stem cell transplantation in a case with acute myeloid leukemia and invasive Schizophyllum commune rhinosinusitis.

Schizophyllum commune, a basidiomycete fungus, is a quite rare cause of invasive sinusitis for which no standard treatment has yet been established. We report herein a 59-year-old woman who developed S. commune rhinosinusitis after remission induction chemotherapy for her acute myeloid leukemia. No causative microorganisms were identified in the sinus lavage fluid culture, whereas nucleotide sequencing of the internal transcribed spacer region using endoscopic sinus biopsy specimen could confirm the pathogen as S. commune. Liposomal amphotericin B and voriconazole (VRCZ) treatment ameliorated both her clinical symptoms and laboratory findings. The patient was successfully treated with allogeneic stem cell transplantation, under continuous VRCZ administration, without aggravation of S. commune sinusitis. Molecular diagnosis and prompt intervention with suitable antifungal drugs may be crucial to manage this rare infectious complication.

Identification of unipotent megakaryocyte progenitors in human hematopoiesis.

The developmental pathway for human megakaryocytes remains unclear, and the definition of pure unipotent megakaryocyte progenitor is still controversial. Using single-cell transcriptome analysis, we have identified a cluster of cells within immature hematopoietic stem- and progenitor-cell populations that specifically expresses genes related to the megakaryocyte lineage. We used CD41 as a positive marker to identify these cells within the CD34+CD38+IL-3RαdimCD45RA- common myeloid progenitor (CMP) population. These cells lacked erythroid and granulocyte-macrophage potential but exhibited robust differentiation into the megakaryocyte lineage at a high frequency, both in vivo and in vitro. The efficiency and expansion potential of these cells exceeded those of conventional bipotent megakaryocyte/erythrocyte progenitors. Accordingly, the CD41+ CMP was defined as a unipotent megakaryocyte progenitor (MegP) that is likely to represent the major pathway for human megakaryopoiesis, independent of canonical megakaryocyte-erythroid lineage bifurcation. In the bone marrow of patients with essential thrombocythemia, the MegP population was significantly expanded in the context of a high burden of Janus kinase 2 mutations. Thus, the prospectively isolatable and functionally homogeneous human MegP will be useful for the elucidation of the mechanisms underlying normal and malignant human hematopoiesis.

Persistent detection of alternatively spliced BCR-ABL variant results in a failure to achieve deep molecular response.

Treatment with tyrosine kinase inhibitors (TKI) may sequentially induce TKI-resistant BCR-ABL mutants in chronic myeloid leukemia (CML). Conventional PCR monitoring of BCR-ABL is an important indicator to determine therapeutic intervention for preventing disease progression. However, PCR cannot separately quantify amounts of BCR-ABL and its mutants, including alternatively spliced BCR-ABL with an insertion of 35 intronic nucleotides (BCR-ABLIns35bp ) between ABL exons 8 and 9, which introduces the premature termination and loss of kinase activity. To assess the clinical impact of BCR-ABL mutants, we performed deep sequencing analysis of BCR-ABL transcripts of 409 samples from 37 patients with suboptimal response to frontline imatinib who were switched to nilotinib. At baseline, TKI-resistant mutations were documented in 3 patients, whereas BCR-ABLIns35bp was detected in all patients. After switching to nilotinib, both BCR-ABL and BCR-ABLIns35bp became undetectable in 3 patients who attained complete molecular response (CMR), whereas in the remaining all 34 patients, BCR-ABLIns35bp was persistently detected, and minimal residual disease (MRD) fluctuated at low but detectable levels. PCR monitoring underestimated molecular response in 5 patients whose BCR-ABLIns35bp was persisted, although BCR-ABLIns35bp does not definitively mark TKI resistance. Therefore, quantification of BCR-ABLIns35bp is useful for evaluating "functional" MRD and determining the effectiveness of TKI with accuracy.

Chd2 interacts with H3.3 to determine myogenic cell fate.

Cell differentiation is mediated by lineage-determining transcription factors. We show that chromodomain helicase DNA-binding domain 2 (Chd2), a SNF2 chromatin remodelling enzyme family member, interacts with MyoD and myogenic gene regulatory sequences to specifically mark these loci via deposition of the histone variant H3.3 prior to cell differentiation. Directed and genome-wide analysis of endogenous H3.3 incorporation demonstrates that knockdown of Chd2 prevents H3.3 deposition at differentiation-dependent, but not housekeeping, genes and inhibits myogenic gene activation. The data indicate that MyoD determines cell fate and facilitates differentiation-dependent gene expression through Chd2-dependent deposition of H3.3 at myogenic loci prior to differentiation.

A co-localization model of paired ChIP-seq data using a large ENCODE data set enables comparison of multiple samples.

Deep sequencing approaches, such as chromatin immunoprecipitation by sequencing (ChIP-seq), have been successful in detecting transcription factor-binding sites and histone modification in the whole genome. An approach for comparing two different ChIP-seq data would be beneficial for predicting unknown functions of a factor. We propose a model to represent co-localization of two different ChIP-seq data. We showed that a meaningful overlapping signal and a meaningless background signal can be separated by this model. We applied this model to compare ChIP-seq data of RNA polymerase II C-terminal domain (CTD) serine 2 phosphorylation with a large amount of peak-called data, including ChIP-seq and other deep sequencing data in the Encyclopedia of DNA Elements (ENCODE) project, and then extracted factors that were related to RNA polymerase II CTD serine 2 in HeLa cells. We further analyzed RNA polymerase II CTD serine 7 phosphorylation, of which their function is still unclear in HeLa cells. Our results were characterized by the similarity of localization for transcription factor/histone modification in the ENCODE data set, and this suggests that our model is appropriate for understanding ChIP-seq data for factors where their function is unknown.

Incidence of refractory cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation.

Post-transplant cytomegalovirus (CMV) disease can be almost completely avoided by current infection control procedures. However, CMV reactivation occurs in more than half of patients, and some patients can develop clinically resistant CMV infections. Whether resistance is due to the host's immune status or a viral resistance mutation is challenging to confirm. Therefore, a prospective observational analysis of refractory CMV infection was conducted in 199 consecutive patients who received allogeneic hematopoietic stem cell transplantation at a single institution. Among them, 143 (72%) patients received anti-CMV drugs due to CMV reactivation, and only 17 (8.5%) exhibited refractory CMV infection. These patients had clinically refractory infection. However, viral genome analysis revealed that only one patient exhibited a mutation associated with the anti-CMV drug resistance. Clinical resistance was mainly correlated with host immune factors, and the incidence of resistance caused by gene mutations was low at the early stage after a transplantation.

The classification of mRNA expression levels by the phosphorylation state of RNAPII CTD based on a combined genome-wide approach.

BACKGROUND: Cellular function is regulated by the balance of stringently regulated amounts of mRNA. Previous reports revealed that RNA polymerase II (RNAPII), which transcribes mRNA, can be classified into the pausing state and the active transcription state according to the phosphorylation state of RPB1, the catalytic subunit of RNAPII. However, genome-wide association between mRNA expression level and the phosphorylation state of RNAPII is unclear. While the functional importance of pausing genes is clear, such as in mouse Embryonic Stem cells for differentiation, understanding this association is critical for distinguishing pausing genes from active transcribing genes in expression profiling data, such as microarrays and RNAseq. Therefore, we examined the correlation between the phosphorylation of RNAPII and mRNA expression levels using a combined analysis by ChIPseq and RNAseq. RESULTS: We first performed a precise quantitative measurement of mRNA by performing an optimized calculation in RNAseq. We then visualized the recruitment of various phosphorylated RNAPIIs, such as Ser2P and Ser5P. A combined analysis using optimized RNAseq and ChIPseq for phosphorylated RNAPII revealed that mRNA levels correlate with the various phosphorylation states of RNAPII. CONCLUSIONS: We demonstrated that the amount of mRNA is precisely reflected by the phased phosphorylation of Ser2 and Ser5. In particular, even the most "pausing" genes, for which only Ser5 is phosphorylated, were detectable at a certain level of mRNA. Our analysis indicated that the complexity of quantitative regulation of mRNA levels could be classified into three categories according to the phosphorylation state of RNAPII.

Random skin biopsy and bone marrow biopsy for diagnosis of intravascular large B cell lymphoma.

Intravascular lymphoma (IVL) is a rare type of extranodal lymphoma in which the lymphoma cells proliferate exclusively in the lumina of small vessels. The diagnosis of IVL requires histological confirmation. Although random skin biopsy from healthy-appearing skin in patients with suspected IVL appeared to be useful, the sensitivity of this method for the diagnosis of IVL remains unknown. We performed a random skin biopsy from 12 consecutive cases of IVL diagnosed at our institution over the past 4 years and evaluate its relevance of clinical and laboratory characteristics, presence or absence of skin lesions, and bone marrow involvement. All 12 patients were diagnosed antemortem by either random skin biopsy or bone marrow biopsy and treated with rituximab-containing chemotherapy. Random skin biopsy was performed in all 12 patients, and the results were positive in ten patients (83.3%). Erythematous skin lesions were seen in 3 of 12 patients, but biopsy was positive for lymphoma lesion in two patients. Bone marrow invasion was seen in 11 of the 12 patients (91.6%) by bone marrow smear and/or flow cytometric analysis, but was detected in only half of the patients by trephine biopsy. We concluded that random skin biopsy from normal-appearing skin is highly sensitive in the diagnosis of IVL comparable to bone marrow trephine biopsy. It should be performed irrespective of the presence or absence of skin lesions in patients who were suspicious of IVL.

Azacitidine for the treatment of patients with relapsed acute myeloid leukemia after allogeneic stem cell transplantation.

We retrospectively analyzed 38 patients with AML who received azacitidine (AZA) to treat disease relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients with objective response (OR) (n = 20) after AZA had significantly higher 2-year overall survival (OS) (45.0% vs 5.6%; p = 0.004) than progressive disease. The 2-year OS was significantly higher in the retransplant group (n = 23) than in the nonretransplant group (n = 15) (34.8% vs 13.3%; p = 0.034). We analyzed 167 patients who underwent the second allo-HSCT to clarify the impact of pretransplant AZA after the second allo-HSCT. Patients in the AZA group (n = 21) had significantly higher 2-year disease-free survival (DFS) (32.7% vs 14.5%; p = 0.012) and OS (38.1% vs 17.5%; p = 0.044) than those in the SOC group (n = 146). Our data demonstrate that AZA is an effective and well-tolerated bridging therapy to the second allo-HSCT.

Cord blood transplantation with a reduced-intensity conditioning regimen using fludarabine and melphalan for adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T-cell lymphoma with a poor prognosis when treated with chemotherapy alone; therefore, allogeneic stem cell transplantation is a consideration. We attempted cord blood transplantation (CBT) using a reduced-intensity conditioning regimen without total body irradiation (non-TBI-RIC) to allow for the best possible timing of transplantation and improve survival outcomes, particularly in older patients. Forty-eight patients (27 male, 21 female) underwent CBT using fludarabine (Flu) 125 mg/m2 and melphalan (Mel) 140 mg/m2 as pre-transplant conditioning. The median age was 32 years (range 44-72), and 21 patients were in complete remission (CR) at the time of CBT. The median duration to neutrophil engraftment (NE) was 19.5 days (range 15-50), with a cumulative incidence of NE of 86.7% at day 50 after CBT. The 1- and 3-year overall survival (OS) rates were 40.4% and 37.7%, respectively. The 3-year OS rate in CR patients was 60.8%, compared with 18.8% in non-CR patients. In ATLL patients, CBT with non-TBI-RIC using Flu/Mel is a promising treatment strategy.

Efficacy of prophylactic letermovir for cytomegalovirus reactivation in hematopoietic cell transplantation: a multicenter real-world data.

A novel anti-cytomegalovirus (CMV) agent, letermovir (LMV), could reportedly improve the outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) recipients because of its high potential to prevent CMV reactivation. Therefore, 685 Japanese allo-HCT recipients, of whom ~80% had a high risk of CMV reactivation, were retrospectively analyzed to assess the impacts of prophylactic LMV on the incidence of clinically significant CMV (csCMV) infection as well as their transplant outcome. By comparing 114 patients who received LMV prophylaxis for a median 92 days to 571 patients without prophylaxis, we observed that prophylactic LMV could significantly (1) reduce the 180-day cumulative incidence of csCMV infection (44.7 vs. 72.4%, p < 0.001), (2) delay the median time until initiation of CMV antigenemia-guided preemptive therapy (90 vs. 36 days, p < 0.001), (3) shorten the duration of anti-CMV preemptive treatment (21 vs. 25 days, p = 0.006), and (4) improve the overall survival rate at 180 days after transplant (80.4 vs. 73.0%, p = 0.033) with a trend of lower non-relapse mortality (8.9 vs. 14.9%, p = 0.052). Our findings demonstrate that prophylactic LMV treatment is highly effective in preventing the development of csCMV infection and ultimately reduces transplant-related mortality.

High risk of hepatitis B-virus reactivation after hematopoietic cell transplantation in hepatitis B core antibody-positive patients.

We investigated the serological changes in hepatitis B virus (HBV)-related markers in 55 and 26 hepatitis B surface antigen (HBsAg)-negative patients undergoing allogeneic and autologous stem cell transplantation, respectively, over the past 4 yr. Five of the 17 allogeneic and one of the five autologous patients with pretransplant anti-hepatitis B core antigen antibodies (anti-HBc) were HBsAg-positive after transplantation, whereas none of the patients negative for anti-HBc were HBsAg-positive in both groups. All patients who became HBsAg-positive received steroid-containing immunosuppressive therapy for chronic graft versus host disease (GVHD) or myeloma. Four of the six patients developed flare of HBV hepatitis, and two patients did not. One patient developed fulminant hepatitis treated with lamivudine and plasma exchange. Other five patients received entecavir from the detection of HBsAg. Although HBV-DNA levels became below the limit of detection in all patients, HBsAg positivity remained in three patients after 6 months of treatment. We concluded that anti-HBc positivity is a risk factor for reactivation of HBV after both autologous and allogeneic transplantation, and HBV-related markers should be monitored regularly in these patients. We also stress the efficacy of pre-emptive use of antiviral agents in controlling HBV replication and limiting hepatic injury due to reactivation of HBV in these patients.

A clinicopathological study of 13 cases of intravascular lymphoma: experience in a single institution over a 9-yr period.

Intravascular lymphoma (IVL) is a rare type of extranodal lymphoma in which the lymphoma cells proliferate exclusively in lumina of small vessels. Here, we report a clinicopathological study of 13 cases IVL diagnosed at our institution between March 1999 and July 2007, and evaluated the clinical characteristics, usefulness of random skin biopsy and response to chemotherapy containing rituximab. Three of 13 patients were diagnosed at autopsy. The most common clinical features were unexplained fever, neurological deterioration, respiratory failure, and poor performance status. Thrombocytopenia, high serum lactate dehydrogenase and soluble interleukin2 receptor levels were the most common laboratory abnormalities. Adrenal tumor was detected in four cases and pituitary involvement was seen in all three autopsied cases and in two surviving patient by brain magnetic resonance imaging. Bone marrow invasion was seen in all 13 cases by bone marrow smear, and it was subtle in trephine biopsy. Immunohistochemical analyses revealed that CD5 was positive in one-third of the cases. Most of the cases were positive for MUM1/IRF, Bcl-2 and negative for CD10 and BCL-6 indicating the postgerminal center cell origin of this peculiar type of lymphoma. On random skin biopsy, the most recent seven patients were diagnosed promptly and chemotherapy containing rituximab was successfully administered. Patients with IVL exhibit the characteristic clinical and immunophenotypic features cited above and the use of random skin biopsy facilitates prompt diagnosis. Early commencement of chemotherapy containing rituximab appears promising for this peculiar lymphoma. As the recent seven patients were diagnosed by random skin biopsy over the past 13 months, the incidence of IVL is thought to be much higher than generally accepted.

Successful chemotherapeutic treatment for metastatic littoral cell angioma: A case report.

RATIONALE: Metastatic littoral cell angioma (LCA) is extremely rare. No standard therapeutic strategy has been established, and the impact of chemotherapy has not yet been evaluated. PATIENT CONCERNS: A 61-year-old woman was admitted because of bicytopenia. She had a splenectomy for LCA of the spleen 10 years earlier. Bone marrow aspiration was normal, and a computed tomography (CT) scan showed hepatomegaly with multiple liver tumors. DIAGNOSES: Liver biopsy samples showed macrophage-like cell infiltration in the hepatic sinusoids. Metastatic LCA was diagnosed based on immunohistochemistry, imaging tests, and the clinical course. INTERVENTIONS: Immunosuppressive agents, such as prednisolone and cyclosporine, were ineffective. Next, cytotoxic agents, such as etoposide, paclitaxel, and vincristine, were administered. OUTCOMES: Cytotoxic agents showed a prominent effect against LCA. CT showed improvement of the hepatomegaly, and fluoro-deoxyglucose (FDG) uptake decreased markedly at a follow-up FDG- positron emission tomography (PET) scan. LESSONS: Chemotherapeutic treatment based on hemophagocytic syndrome or angiosarcoma might have anti-tumor activity against metastatic LCA. Analysis of the molecular characteristics of this tumor is needed to develop better treatment options.

Use of random skin biopsy for diagnosis of intravascular large B-cell lymphoma.

Intravascular lymphoma (IVL) is a rare type of extranodal lymphoma with an aggressive clinical course characterized by proliferation of large lymphoma cells within the lumina of the small vessels. Because of its varied clinical symptoms and the absence of lymphadenopathy, diagnosis of IVL is extremely difficult and requires histological confirmation. We report here 6 consecutive patients with IVL, admitted to Kameda General Hospital, Kamogawa-shi, Japan, from June 7, 2006, to February 28, 2007, whose IVL was diagnosed by random skin biopsy of healthy-appearing skin. Three patients presented with progressive neurological deterioration and 2 others with hypoxemia with interstitial infiltration on chest radiography. One patient presented with confusion and severe hypoxia without apparent interstitial infiltration. Two patients showed localized skin involvement. Irrespective of the presence of skin lesions, almost all skin biopsy specimens showed obliteration of small vessels of subcutaneous fat tissues by lymphoma cells, allowing a prompt diagnosis of IVL. Early institution of rituximab-based chemotherapy induced favorable responses in all patients treated. Because diagnosis based on tissue other than skin is usually difficult in patients with suspected IVL, random skin biopsy should be considered even in patients with no evident skin lesions.

[Primary amyloidosis associated with IgD-lambda M-proteinemia].

We describe here a case of primary AL amyloidosis associated with IgD monoclonal gammopathy of undetermined significance. A 73-year-old man was referred to our hospital with suspected multiple myeloma due to renal failure and urinary Bence Jones protein. Although serum electrophoresis revealed IgDlambda monoclonal protein, the bone marrow did not showed plasma cell proliferation. Systemic bone survey disclosed no lytic bone lesions. Because the patient had macroglossia and multiple ecchymosis in the face and neck, primary amyloidosis was suspected. Skin biopsy revealed extensive deposition of amyloid which was positively stained by Congo red dye. A diagnosis of primary AL amyloidosis associated with IgD monoclonal gammopathy was made. The patient was also complicated renal failure that eventually needed hemodialysis. To our knowledge, this is the first report of primary AL amyloidosis associated with IgD monoclonal gammopathy with undetermined significance.