Dissecting the impact of bromodomain inhibitors on the Interferon Regulatory Factor 4-MYC oncogenic axis in multiple myeloma

B-cell progenitor fate determinant interferon regulatory factor 4 (IRF4) exerts key roles in the pathogenesis and progression of multiple myeloma (MM), a currently incurable plasma cell malignancy. Aberrant expression of IRF4 and the establishment of a positive auto-regulatory loop with oncogene MYC, drives a MM specific gene-expression program leading to the abnormal expansion of malignant immature plasma cells. Targeting the IRF4-MYC oncogenic loop has the potential to provide a selective and effective therapy for MM. Here we evaluate the use of bromodomain inhibitors to target the IRF4-MYC axis through combined inhibition of their known epigenetic regulators, BRD4 and CBP/EP300. Although all inhibitors induced cell death, we found no synergistic effect of targeting both of these regulators on the viability of MM cell-lines. Importantly, for all inhibitors over a time period up to 72 h, we detected reduced IRF4 mRNA, but a limited decrease in IRF4 protein expression or mRNA levels of downstream target genes. This indicates that inhibitor-induced loss of cell viability is not mediated through reduced IRF4 protein expression, as previously proposed. Further analysis revealed a long half-life of IRF4 protein in MM cells. In support of our experimental observations, gene network modeling of MM suggests that bromodomain inhibition is exerted primarily through MYC and not IRF4. These findings suggest that despite the autofeedback positive regulatory loop between IRF4 and MYC, bromodomain inhibitors are not effective at targeting IRF4 in MM and that novel therapeutic strategies should focus on the direct inhibition or degradation of IRF4.

Sickle cell disease: an update

Sickle cell disease is a common inherited disorder that is characterised by chronic haemolysis and vaso-occlusive episodes, resulting in severe pain and end-organ damage. The most frequent acute manifestation of sickle cell disease is a painful vaso-occlusive crisis, which can, in some cases, develop into a sickle chest crisis: a life-threatening complication of sickle cell disease that requires early recognition and prompt intervention to prevent progressive respiratory failure. In addition to the acute complications, patients with sickle cell disease are also at risk of a number of chronic complications that require multidisciplinary specialist input.

Acute leukaemia: no reason to panic

Acute leukaemia is characterised by uncontrolled expansion of immature leukocytes, either myeloid or lymphoid progenitors, leading to acute myeloid leukaemia (AML) and acute lymphoid leukaemia (ALL), respectively. If left untreated, it is life-threatening and can lead to death within weeks. When acute leukaemia is suspected, urgent haematology input should be sought. Appropriate investigations are needed promptly to confirm diagnosis and start treatment. A multidisciplinary approach is vital to ensure appropriate management.

Lymphocytosis and chronic lymphocytic leukaemia: investigation and management

Lymphocytosis is a common blood-test finding. Establishing whether the cause of lymphocytosis is benign or malignant is key to managing patients appropriately. A lymphocytosis should always prompt clinical review including a thorough history, examination and appropriate preliminary investigations (blood tests, blood film). The majority of patients with chronic lymphocytic leukaemia (CLL) present incidentally due to a lymphocytosis found on routine blood tests. Patient outcomes vary considerably based on genetic pre-disposition and various prognostic markers (age, Binet or Rai staging, and B2-microglobulin). Although not curative, chemo-immunotherapy is an effective treatment strategy for the majority of CLL patients with progressive disease. More recently, novel oral therapies have been developed that target key signalling and apoptosis pathways and that are being used in relapse settings and as first-line treatments for certain patients.

Thrombocytopenia: the good, the bad and the ugly

New thrombocytopenia may be associated with a variety of conditions and diagnosis can be challenging. Presentation can vary from life-threatening bleeding or thrombosis to an incidental finding in an asymptomatic patient. New thrombocytopenia requires urgent investigation. Investigations are mainly guided by findings from the clinical history, physical examination, full blood count and blood film analysis. Aside from the actively bleeding patient, rare but life-threatening causes of thrombocytopenia must be identified early as they require urgent treatment. These include thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, suspicion of new acute promyelocytic leukaemia, and vaccine-induced prothrombotic immune thrombocytopenia. Here, we discuss how to approach a patient with new thrombocytopenia, along with key differentials not to be missed.

Management of adverse events in patients with acute myeloid leukemia in remission receiving oral azacitidine: experience from the phase 3 randomized QUAZAR AML-001 trial

Background

Most older patients with acute myeloid leukemia (AML) who attain morphologic remission with intensive chemotherapy (IC) will eventually relapse and post-relapse prognosis is dismal. In the pivotal QUAZAR AML-001 trial, oral azacitidine maintenance therapy significantly prolonged overall survival by 9.9 months (P < 0.001) and relapse-free survival by 5.3 months (P < 0.001) compared with placebo in patients with AML in first remission after IC who were not candidates for transplant. Currently, the QUAZAR AML-001 trial provides the most comprehensive safety information associated with oral azacitidine maintenance therapy. Reviewed here are common adverse events (AEs) during oral azacitidine treatment in QUAZAR AML-001, and practical recommendations for AE management based on guidance from international cancer consortiums, regulatory authorities, and the authors’ clinical experience treating patients in the trial.

Methods

QUAZAR AML-001 is an international, placebo-controlled randomized phase 3 study. Patients aged ≥ 55 years with AML and intermediate- or poor-risk cytogenetics at diagnosis, who had attained first complete remission (CR) or CR with incomplete blood count recovery (CRi) within 4 months before study entry, were randomized 1:1 to receive oral azacitidine 300 mg or placebo once-daily for 14 days in repeated 28-day cycles. Safety was assessed in all patients who received ≥ 1 dose of study drug.

Results

A total of 469 patients received oral azacitidine (n = 236) or placebo (n = 233). Median age was 68 years. Patients received a median of 12 (range 1–80) oral azacitidine treatment cycles or 6 (1–73) placebo cycles. Gastrointestinal AEs were common and typically low-grade. The most frequent grade 3–4 AEs during oral azacitidine therapy were hematologic events. AEs infrequently required permanent discontinuation of oral azacitidine (13%), suggesting they were effectively managed with use of concomitant medications and oral azacitidine dosing modifications.

Conclusion

Oral azacitidine maintenance had a generally favorable safety profile. Prophylaxis with antiemetic agents, and blood count monitoring every other week, are recommended for at least the first 2 oral azacitidine treatment cycles, and as needed thereafter. Awareness of the type, onset, and duration of common AEs, and implementation of effective AE management, may maximize treatment adherence and optimize the survival benefits of oral azacitidine AML remission maintenance therapy.

Trial registration This trial is registered on clinicaltrials.gov: NCT01757535 as of December 2012.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01142-x.

Real-world experience of SARS-CoV-2 antibody assays in UK healthcare workers

BACKGROUND

The seroprevalence of antibodies to SARS-CoV-2 in healthcare workers is variable throughout the world. This study compares the use of two antibody assays among large cohorts of healthcare workers in southern England.

METHODS

This cohort study includes data obtained from staff at Western Sussex Hospitals NHS Foundation Trust (WSHT) and Brighton and Sussex University Hospitals (BSUH) during voluntary antibody testing, using Abbott and Roche SARS-CoV-2 antibody assays at each Trust respectively.

RESULTS

The observed seroprevalence level was 7.9% for the WSHT/Abbott cohort versus 13% for the BSUH/Roche cohort. Based on a previous positive PCR, we find that the false-negative rate of the Abbott and Roche assays were 60.2% and 19% respectively, implying sensitivity levels of 39.8% and 81%. Within these cohorts, seropositivity was most strongly associated with those of South Asian ethnicity, allied health professionals and male sex (p<0.0001).

CONCLUSIONS

In this real-world study, neither antibody test performed to the specification level stated by the manufacturer. More rigorous testing of these and other assays in target populations is recommended prior to widespread usage if they are to provide data that might be useful to control the pandemic.

Von Willebrand factor (vWF): marker of endothelial damage and thrombotic risk in COVID-19?

BACKGROUND

COVID-19 infection is characterised, among other features, by a prothrombotic state with high rate of venous thromboembolism (VTE), D-dimer, and fibrinogen levels. Clinical observations have also highlighted that these patients have elevated von Willebrand factor (vWF) and factor VIIIc.

METHODS

24 consecutive COVID-19 positive patients were selected from the intensive care unit (ICU) or the high acuity ward of Brighton and Sussex University Hospitals NHS Trust.

RESULTS

The rate of VTE was 25% and mortality rate was 16.7%. Fibrinogen and D-Dimers were elevated, 7.9 (1.6) g/L and 2.4 (2.02) ug/ml respectively. Factor VIIIc and von vWF antigen levels were both extremely elevated at 279 (148) u/dL and 350 (131) % respectively, which are comparable to levels seen in ICU patients with severe sepsis. vWF levels were significantly higher in patients that died (p=0.017) and showed a positive correlation with age. There was a statistically significant association between COVID-19 disease and non-O blood group (p=0.02); 80% (4/5) of COVID-19 patients with VTE were blood group A.

CONCLUSION

Very high levels of vWF and factor VIIIc are common in COVID-19 patients, comparable to levels in severely septic non-COVID ICU patients. This could contribute to the hypercoagulable state and increased VTE rate in COVID-19. Further studies are needed to evaluate the use of vWF for stratifying thrombotic risk in COVID-19 and to determine if elevated vWF is contributing to disease pathogenesis.

Chronic Lymphocytic Leukaemia in 2020: the Future Has Arrived

PURPOSE OF REVIEW

Chronic lymphocytic leukaemia is now recognised as a heterogenous disease with a variety of clinical outcomes. Here we summarise the way it is currently stratified according to genetic risk and patient characteristics and the treatment approaches used for these different subgroups.

RECENT FINDINGS

Certain patients appear to sustain MRD negativity after combination chemoimmunotherapy, leading to the suggestion that their CLL may be cured. However, 17p-deleted, p53-mutated or IGHV-UM subgroups are generally resistant to FCR, and much better responses are seen with ibrutinib and venetoclax, frequently inducing MRD negativity that hopefully will be translated into durable remissions. Small molecule inhibitors have already revolutionised CLL treatment. Going forward, we anticipate their use in the majority of patients, early after diagnosis and with curative intent.

Dissecting the role of the CXCL12/CXCR4 axis in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is the most common adult acute leukaemia with the lowest survival rate. It is characterised by a build-up of immature myeloid cells anchored in the protective niche of the bone marrow (BM) microenvironment. The CXCL12/CXCR4 axis is central to the pathogenesis of AML as it has fundamental control over AML cell adhesion into the protective BM niche, adaptation to the hypoxic environment, cellular migration and survival. High levels of CXCR4 expression are associated with poor relapse-free and overall survival. The CXCR4 ligand, CXCL12 (SDF-1), is expressed by multiple cells types in the BM, facilitating the adhesion and survival of the malignant clone. Blocking the CXCL12/CXCR4 axis is an attractive therapeutic strategy providing a 'multi-hit' therapy that both prevents essential survival signals and releases the AML cells from the BM into the circulation. Once out of the protective niche of the BM they would be more susceptible to destruction by conventional chemotherapeutic drugs. In this review, we disentangle the diverse roles of the CXCL12/CXCR4 axis in AML. We then describe multiple CXCR4 inhibitors, including small molecules, peptides, or monoclonal antibodies, which have been developed to date and their progress in pre-clinical and clinical trials. Finally, the review leads us to the conclusion that there is a need for further investigation into the development of a 'multi-hit' therapy that targets several signalling pathways related to AML cell adhesion and maintenance in the BM.

Acute Myeloid Leukaemia in Its Niche: the Bone Marrow Microenvironment in Acute Myeloid Leukaemia

Purpose of Review

Acute myeloid leukaemia (AML) is a heterogeneous malignancy for which treatment options remain suboptimal. It is clear that a greater understanding of the biology of the AML niche will enable new therapeutic strategies to be developed in order to improve treatment outcomes for patients.

Recent Findings

Recent evidence has highlighted the importance of the bone marrow microenvironment in protecting leukaemia cells, and in particular leukaemic stem cells from chemotherapy-induced cell death. This includes mesenchymal stem cells supporting growth and preventing apoptosis, and altered action and secretion profiles of other niche components including adipocytes, endothelial cells and T cells.

Summary

Here, we provide a detailed overview of the current understanding of the AML bone marrow microenvironment. Clinical trials of agents that mobilise leukaemic stem cells from the bone marrow are currently ongoing and show early promise. Future challenges will involve combining these novel therapies targeted at the AML niche with conventional chemotherapy treatment.

Real-world experience of ibrutinib therapy in relapsed chronic lymphocytic leukemia: results of a single-center retrospective analysis

Background

Ibrutinib is a Bruton’s tyrosine-kinase (BTK) inhibitor that is approved as a second-line treatment in chronic lymphocytic leukemia (CLL). While recent trials have demonstrated impressive results for ibrutinib, there remains a paucity of real-world data on its use in the clinical setting.

Methods

In this single-center study carried out at Brighton and Sussex University Hospitals, we retrospectively compared outcomes in 38 patients with relapsed CLL who received ibrutinib versus those who received conventional first- and second-line therapies.

Results

Our results demonstrate improved progression-free survival (PFS, p=0.022) with ibrutinib versus conventional second-line therapies and survival comparable to conventional first-line therapies. However, there was a high frequency (81.6%) of adverse events associated with ibrutinib therapy, including 2 cases of death secondary to sepsis and a further 7 cases of discontinuation of treatment due to adverse events. We also identify del13q14.3 as an adverse predictor of response to ibrutinib with respect to both overall survival (p=0.014) and PFS (p=0.008), suggesting that these patients may be better suited to receiving the BCL2 inhibitor venetoclax.

Conclusion

Whilst there is robust evidence for improved outcomes with ibrutinib, we find that survival in patients with del13q14.3 is reduced and that the rate of adverse events and discontinuation in clinical practice is higher than anticipated from clinical trials.

Targeting SHP-1, 2 and SHIP Pathways: A Novel Strategy for Cancer Treatment?

Well-balanced levels of tyrosine phosphorylation, maintained by the reversible and coordinated actions of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), are critical for a wide range of cellular processes including growth, differentiation, metabolism, migration, and survival. Aberrant tyrosine phosphorylation, as a result of a perturbed balance between the activities of PTKs and PTPs, is linked to the pathogenesis of numerous human diseases, including cancer, suggesting that PTPs may be innovative molecular targets for cancer treatment. Two PTPs that have an important inhibitory role in haematopoietic cells are SHP-1 and SHP-2. SHP-1, 2 promote cell growth and act by both upregulating positive signaling pathways and by downregulating negative signaling pathways. SHIP is another inhibitory phosphatase that is specific for the inositol phospholipid phosphatidylinositol-3,4,5-trisphosphate (PIP3). SHIP acts as a negative regulator of immune response by hydrolysing PIP3, and SHIP deficiency results in myeloproliferation and B-cell lymphoma in mice. The validation of SHP-1, 2 and SHIP as oncology targets has generated interest in the development of inhibitors as potential therapeutic agents for cancers; however, SHP-1, 2 and SHIP have proven to be an extremely difficult target for drug discovery, primarily due to the highly conserved and positively charged nature of their PTP active site, and many PTP inhibitors lack either appro-priate selectivity or membrane permeability. To overcome these caveats, novel techniques have been employed to synthesise new inhibitors that specifically attenuate the PTP-dependent signaling inside the cell and amongst them; some are already in clinical development which are discussed in this review.

Use of FDG PET/CT in identification of bone marrow involvement in diffuse large B cell lymphoma and follicular lymphoma: comparison with iliac crest bone marrow biopsy

Background Non-Hodgkin's lymphoma (NHL) accounts for around 4% of new cancer cases annually. Bone marrow involvement is important for staging and management. Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) is used increasingly to identify this, in addition to bone marrow biopsy (BMB), which is seen as "gold" reference standard. Purpose To compare determination of bone marrow involvement by FDG PET/CT against BMB in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). Material and Methods This was a retrospective study of patients with histologically confirmed NHL at a single UK cancer center undergoing pre-treatment FDG PET/CT and BMB between June 2010 and February 2013. Information was collected from patient notes, cancer registry, histological and imaging reports. Diagnostic accuracy of FDG PET/CT was determined, compared to BMB as the reference standard. Results Twenty-four patients with DLBCL and 12 with FL were included. Five DLBCL patients had bone marrow involvement on PET/CT; all were confirmed on BMB. Three FL patients had marrow involvement on PET/CT but not on BMB; one FL patient had positive BMB but negative PET/CT. Using BMB as the reference standard, the sensitivity and specificity of FDG PET/CT for detecting bone marrow involvement in DLBCL were 100% and 100%, respectively, and in FL were 0% and 72.7%, respectively. Conclusion FDG PET/CT is accurate for detection of bone marrow involvement in newly diagnosed DLBCL, but not FL. In DLBCL, positive FDG PET/CT may negate the need for routine BMB, although BMB in addition or combination may be appropriate if this would influence management or prognosis.

The hypomethylating agent Decitabine causes a paradoxical increase in 5-hydroxymethylcytosine in human leukemia cells

The USFDA approved "epigenetic drug", Decitabine, exerts its effect by hypomethylating DNA, demonstrating the pivotal role aberrant genome-wide DNA methylation patterns play in cancer ontology. Using sensitive technologies in a cellular model of Acute Myeloid Leukemia, we demonstrate that while Decitabine reduces the global levels of 5-methylcytosine (5mC), it results in paradoxical increase of 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) levels. Hitherto, the only biological mechanism known to generate 5hmC, 5fC and 5caC, involving oxidation of 5mC by members of Ten-Eleven-Translocation (TET) dioxygenase family, was not observed to undergo any alteration during DAC treatment. Using a multi-compartmental model of DNA methylation, we show that partial selectivity of TET enzymes for hemi-methylated CpG dinucleotides could lead to such alterations in 5hmC content. Furthermore, we investigated the binding of TET1-catalytic domain (CD)-GFP to DNA by Fluorescent Correlation Spectroscopy in live cells and detected the gradual increase of the DNA bound fraction of TET1-CD-GFP after treatment with Decitabine. Our study provides novel insights on the therapeutic activity of DAC in the backdrop of the newly discovered derivatives of 5mC and suggests that 5hmC has the potential to serve as a biomarker for monitoring the clinical success of patients receiving DAC.

Nanog requires BRD4 to maintain murine embryonic stem cell pluripotency and is suppressed by bromodomain inhibitor JQ1 together with Lefty1

Embryonic stem cells (ESCs) are maintained in an undifferentiated state through expression of the core transcriptional factors Nanog, Oct4, and Sox2. However, the epigenetic regulation of pluripotency is poorly understood. Differentiation of ESCs is accompanied by a global reduction of panacetylation of histones H3 and H4 suggesting that histone acetylation plays an important role in maintenance of ESC pluripotency. Acetylated lysine residues on histones are read by members of the bromodomain family that includes BET (bromodomain and extraterminal domain) proteins for which highly potent and selective inhibitors have been developed. In this study we demonstrate that the pan-BET bromodomain inhibitor JQ1 induces rapid spontaneous differentiation of murine ESCs by inducing marked transcriptional downregulation of Nanog as well as the stemness markers Lefty1 and Lefty2, but not Myc, often used as a marker of BET inhibitor activity in cancer. We show that the effects of JQ1 are recapitulated by knockdown of the BET family member BRD4 implicating this protein in Nanog regulation. These data are also supported by chromatin immunoprecipitation experiments which confirm BRD4 binding at the Nanog promoter that is known to require acetylation by the histone acetyltransferase MOF for transcriptional activity. In further support of our findings, we show that JQ1 antagonizes the stem cell-promoting effects of the histone deacetylase inhibitors sodium butyrate and valproic acid. Our data suggest that BRD4 is critical for the maintenance of ESC pluripotency and that this occurs primarily through the maintenance of Nanog expression.

DNMT3A: the DioNysian MonsTer of acute myeloid leukaemia

In the mythology of Ancient Greece, there was often a creative tension between the opposing forces of the gods Apollo and Dionysius, the two sons of Zeus. The Apollonian force was considered to be rational and lifegiving, whilst Dionysian forces were chaotic and elemental. Acute myeloid leukaemia is characterised by the clash of these forces: the chaotic proliferation of immature myeloid cells in the bone marrow overcomes the normal, orderly production of healthy blood cells. DNMT3A mutations occur early in the leukaemogenic process and may even act as "founder" mutations - the first step in a pathway towards malignant transformation. As such, these mutations may represent a Dionysian agent of disorder, inciting the chaotic myeloid proliferation and arrest of differentiation which are hallmarks of AML. This review will focus on the role of DNMT3A mutations in leukaemia pathogenesis, their influence on prognosis, and the potential for therapeutic targeting.

Haematology patients and the Internet--the use of on-line health information and the impact on the patient-doctor relationship

OBJECTIVE

Patients access on-line health information (OHI) to better understand their health. We aimed to determine which demographic factors influence OHI use. We also explored how OHI is used and subsequent implications to the patient-doctor relationship.

METHODS

We distributed a self-administered questionnaire to 202 haematology out-patients.

RESULTS

62.3% used the internet and 54.3% used OHI. Higher education, (P<0.001, OR 34.62, 95% CI 5.20-230.66) and household incomes of £15000-25000 (P=0.023 OR 4.8 95% CI 1.236-18.59) were positively associated with OHI use. Those reassured after reading OHI had improved trust in their specialist (P<0.001, OR 52.1, 95% CI 12.3-221.1), improved confidence during consultations, (P<0.001, OR 23.0, 95% CI 2.8-188.2) and were improved decisions makers (P=0.008, OR 13.6, 95% CI 4.1-45.7). Those with increased trust in their haematologist also had improved confidence (P<0.001, OR 6.2, 95% CI 2.2-17.3) and improved decision making ability (P<0.001, OR 13.6, 95% CI 4.7-39.4). 74.6% of patients did not share OHI with their haematologist.

CONCLUSIONS

Two-thirds of participants were exposed directly or indirectly to OHI. OHI affects patients' view of their health and influences behaviour during consultations.

PRACTICE IMPLICATIONS

Haematologists could facilitate patients using OHI by recommending high quality websites and act supportively when patients share OHI.

Absolute lymphocyte count at day 29 of treatment is a powerful predictor of outcome in multiple myeloma

BACKGROUND

Survival outcomes for patients who receive treatment for newly diagnosed multiple myeloma (MM) are highly variable.

PATIENTS AND METHODS

We conducted a retrospective analysis of 38 unselected MM patients who received treatment with cyclophosphamide, thalidomide, and dexamethasone to evaluate the prognostic value of the absolute lymphocyte count at diagnosis and at the end of the initial cycle of treatment defined as day 29, termed ALC-29. The median follow-up was 54 months (range, 2-83 months).

RESULTS

We found that ALC-29, as a continuous variable, was a predictor of overall survival (OS) in MM patients (hazard ratio, 0.208; 95% confidence interval, 0.093-0.689; P = .007). Patients with an ALC-29 ≥ 0.8 × 10(9)/L (n = 16) experienced a superior median OS compared with patients with an ALC-29 < 0.8 × 10(9)/L (n = 22) with a median OS of 58.3 months versus 42.5 months respectively (P = .006). Multivariate analysis confirmed that ALC-29 ≥ 0.8 × 10(9)/L was an independent prognostic indicator of OS in our cohort of MM patients.

CONCLUSION

We concluded that the ALC-29 is a useful and simple predictor of outcome in newly diagnosed MM patients who receive standard chemotherapy. Our results support the hypothesis that host immunity plays an important role in tumor control in MM.

Elacytarabine in relapsed/refractory acute myeloid leukaemia: an evaluation of clinical efficacy, pharmacokinetics, cardiac safety and effects on lipid profile

Elacytarabine is the elaidic acid ester derivative of cytarabine, designed to enter cells independently of nucleoside transporters. Effects of elacytarabine on QT interval, serum lipid profile and clinical activity were investigated in 43 relapsed/refractory AML patients. Mean maximum increase in corrected QT interval of 24( ± 29)ms occurred 48 h after elacytarabine infusion without associated arrhythmias or clinical symptoms. A non-clinically significant, elacytarabine exposure-dependent increase in cholesterol was caused by a cholesterol rich lipoprotein depleted of apolipoprotein B formed by infused phospholipids complexing cholesterol. Elacytarabine is clinically active in relapsed/refractory AML: overall response rate (CR + CRi) was 44% (16/36 with 7 non-evaluable patients) and adverse events were manageable. Clinical Trials.gov Identifier: NCT01258816.

Pregnancy in Shwachman-Diamond syndrome: a novel genetic mutation with minimal consequence

Shwachman-Diamond syndrome (SDS) is a rare inherited bone marrow failure syndrome, characterised by neutropenia, exocrine pancreatic dysfunction and often skeletal abnormalities. To date, and to our knowledge, we report a novel genetic mutation in SDS that, we believe, is associated with minimal consequence,and report the fertility and pregnancy in this individual.

Diffuse large B-cell lymphoma: an unusual cause of severe otalgia and facial palsy

An elderly woman, two months after chemotherapy for diffuse large B-cell lymphoma, presented with left-sided otalgia, discharge and facial nerve palsy. MRI showed an active left mastoid infection with an ear canal lesion, likely to be a cholesteatoma. However, a biopsy of the mass showed recurrent high-grade lymphoma. Following diagnosis, the patient opted for palliative care within the community and consequently passed away a few weeks later.

Severe global DNA hypomethylation blocks differentiation and induces histone hyperacetylation in embryonic stem cells

It has been reported that DNA methyltransferase 1-deficient (Dnmt1-/-) embryonic stem (ES) cells are hypomethylated (20% CpG methylation) and die through apoptosis when induced to differentiate. Here, we show that Dnmt[3a-/-,3b-/-] ES cells with just 0.6% of their CpG dinucleotides behave differently: the majority of cells within the culture are partially or completely blocked in their ability to initiate differentiation, remaining viable while retaining the stem cell characteristics of alkaline phosphatase and Oct4 expression. Restoration of DNA methylation levels rescues these defects. Severely hypomethylated Dnmt[3a-/-,3b-/-] ES cells have increased histone acetylation levels, and those cells that can differentiate aberrantly express extraembryonic markers of differentiation. Dnmt[3a-/-,3b-/-] ES cells with >10% CpG methylation are able to terminally differentiate, whereas Dnmt1-/- ES cells with 20% of the CpG methylated cannot differentiate. This demonstrates that successful terminal differentiation is not dependent simply on adequate methylation levels. There is an absolute requirement that the methylation be delivered by the maintenance enzyme Dnmt1.

Autoimmunity as the consequence of a spontaneous mutation in Rasgrp1

A mouse strain was identified with a recessive genetic lesion, which spontaneously developed a lymphoproliferative autoimmune syndrome exhibiting features of systemic lupus erythematosus. Positional mapping of the disease-associated locus revealed a lesion in Rasgrp1 that prevented the translation of the RasGRP1 protein. T cells from these mice failed to activate Ras or proliferate vigorously following antigen encounter and showed defects in positive selection. Peripheral RasGRP1lag T cells spontaneously adopted a memory phenotype and were able to transfer disease to lymphopenic recipient mice. CD4+ T cells accumulated in the lymphoid tissues of older RasGRP1lag mice and were resistant to activation-induced cell death. RasGRP1lag B cells were functionally normal, but activated B cells were detected in older mice, as were autoantibodies directed against self-antigens. Our findings indicate that Ras signaling pathways are required to maintain T cell tolerance and to prevent autoimmune disease.

Insights into the role of DNA methylation in murine embryonic stem cells using a modified tetracycline-inducible gene expression system

Murine embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of the mouse blastocyst. Their ability to differentiate into diverse cell types in vitro has served well as a model of early embryonic developmental processes. A powerful strategy for studying the role of key genes during this time is to be able to regulate their expression in a dose-dependent manner. Here, we outline our experience of applying the "tetracycline-inducible system" to study gene function during ES cell differentiation and describe a number of key modifications designed to overcome the central problem of transgene silencing. Finally, we demonstrate how this approach can yield insights into the role of DNA methylation during ES cell differentiation by studying the function of two genes: DNMT3A, involved in the de novo methylation of cytosine bases, and MBD2b, a methyl-dependent co-repressor and putative cytosine demethylase.