Atypical Presentation of Acute Myeloid Leukemia

We present a case of a 48-year-old male who presented with worsening pleuritic chest pain for 2 h. He also complained of fever, malaise, headache and severe neck pain. Electrocardiogram (ECG) showed ST segment elevation in leads I, II, aVL and V5 with PR elevation and ST depression in aVR. On admission, troponin-I was 14.8 ng/mL. Based on ECG changes, elevated troponin and family history of early coronary artery disease, the patient was emergently taken to cardiac catheterization lab. Angiography showed non-obstructive coronaries, mild hypokinesis of mid inferior and anterolateral wall with ejection fraction (EF) of 40-45%. Based on above presentation and angiography findings, the diagnosis of acute myopericarditis was made. He was started on colchicine and ibuprofen. The other workup to determine etiology of myopericarditis was negative as shown below. Given the history of fever, headache and worsening neck pain, we also became suspicious of meningitis. Lumbar puncture was performed which was negative. On the day of admission, he was found to have blasts on complete blood count and peripheral smear. Bone marrow biopsy and flow cytometry confirmed the diagnosis of acute myeloid leukemia (AML). He received induction and salvage therapy. Repeat bone marrow confirmed complete remission and normal cytogenetics. Although pericardial or myocardial biopsies are unavailable for our patient, in the absence of other causes, it does appear that his acute myopericarditis was associated with AML.

Generation of Genetic Knockouts in Myeloid Cell Lines Using a Lentiviral CRISPR/Cas9 System

CRISPR/Cas9-based gene targeting allows deletion of a gene of interest from cultured cell lines. Due to difficulty in transiently transfecting hematopoetic cells with components required for this process, we have adopted a lentiviral system for delivery of the CRISPR/Cas9 components into myeloid cell lines. Here, we detail the process of knocking out genes from pools of cultured myeloid cells using this CRISPR/Cas9 system and describe methods of validating these knockout pools.

Prognostic Value of EVI1 Expression in Pediatric Acute Myeloid Leukemia: A Systematic Review

Acute myeloid leukemia (AML) as a distortion of blood cells involves the differ entiation of hematopoietic stem cells. Several studies established the irregular over expression of specific genes is a common finding in patients with AML. The ectopic viral integration site-1 (EVI1) gene is a protooncogene subject to alternative splicing, and encodes a zincfinger protein that acts as a transcriptional regulator in early devel opment. Forced overexpression of EVI1 in hematopoietic progenitors later induced a myeloid differentiation block. The current review aimed at determining the prognos tic value of EVI1 expression in patients with AML in the age range of one month to fifteen years. The scientific databases including PubMed, Google Scholar, EMBASE, Scopus, and ISI published up to January 2016 were searched using the conformity keywords and a total of four articles were studied. Three articles declared higher overexpression of EVI1 in patients with mixed-lineage leukemia (MLL) rearrangements. The percentage of overall survival (OS), reported in two articles, decreased in AML patients with high EVI1 expression. A study reported that the relationship between EVI1 expression and OS was negligible in cases with and without EVI1 expression. Another study showed significant differences in event free survival (EFS) and OS in the group of patients with positive MLL-AF9 between EVI1+ and EVI1patients. The current study revealed that high EVI1 expression was not a poor prognostic factor in pediatric patients with AML. And this gene expression was mainly prognostic concomitantly by other factors such as MLL rearrangement, MEL1 expression, and white blood cell (WBC) count.

Myeloid Progenitor Transformation Assay

Numerous oncogenes have been identified to cause leukemia. For example, chromosomal translocation generates various fusion genes of the mixed-lineage leukemia (MLL) gene and a partner gene in leukemia, whose gene products transform primary myeloid progenitors into an immortalized state. To characterize the transforming ability of leukemic oncogenes, researchers in the field have developed an ex vivo murine myeloid transformation assay using retroviral gene transduction and its protocol has been improved over the past 10 years. Here, we provide the detailed procedure for this assay.

Myeloid P2Y2 receptor promotes acute inflammation but is dispensable for chronic high-fat diet-induced metabolic dysfunction

The purinergic receptor P2Y2 binds ATP to control chemotaxis of myeloid cells, and global P2Y2 receptor knockout mice are protected in models of acute inflammation. Chronic inflammation mediated by macrophages and other immune cells in adipose tissue contributes to the development of insulin resistance. Here, we investigate whether mice lacking P2Y2 receptors on myeloid cells are protected against acute and chronic inflammation. Wild-type mice were transplanted with either wild-type or P2Y2 receptor null bone marrow and treated with a sublethal dose of endotoxin as a model of acute inflammation, or fed a high-fat diet to induce obesity and insulin resistance as a model of chronic inflammation. P2Y2^-/- chimeric mice were protected against acute inflammation. However, high-fat diet feeding induced comparable inflammation and insulin resistance in both WT and P2Y2^-/- chimeric mice. Of note, confocal microscopy revealed significantly fewer crown-like structures, assemblies of macrophages around adipocytes, in P2Y2^-/- chimeric mice compared to WT chimeric mice. We conclude that P2Y2 receptors on myeloid cells are important in mediating acute inflammation but are dispensable for the development of whole body insulin resistance in diet-induced obese mice.

Late onset Alzheimer's disease genetics implicates microglial pathways in disease risk

Alzheimer's disease (AD) is a highly heritable complex disease with no current effective prevention or treatment. The majority of drugs developed for AD focus on the amyloid cascade hypothesis, which implicates Aß plaques as a causal factor in the disease. However, it is possible that other underexplored disease-associated pathways may be more fruitful targets for drug development. Findings from gene network analyses implicate immune networks as being enriched in AD; many of the genes in these networks fall within genomic regions that contain common and rare variants that are associated with increased risk of developing AD. Of these genes, several (including CR1, SPI1, the MS4As, TREM2, ABCA7, CD33, and INPP5D) are expressed by microglia, the resident immune cells of the brain. We summarize the gene network and genetics findings that implicate that these microglial genes are involved in AD, as well as several studies that have looked at the expression and function of these genes in microglia and in the context of AD. We propose that these genes are contributing to AD in a non-Aß-dependent fashion.

Effectiveness of environmental control measures to decrease the risk of invasive aspergillosis in acute leukaemia patients during hospital building work

BACKGROUND

Invasive aspergillosis (IA) is a significant problem in acute leukaemia patients. Construction work near hospital wards caring for immunocompromised patients is one of the main risk factors for developing invasive pulmonary aspergillosis (IPA).

AIM

To assess the impact of environmental control measures used during hospital construction for the prevention of IA in acute leukaemia patients.

METHODS

A retrospective cohort study was developed to evaluate the IA incidence in acute leukaemia patients with different environmental control measures employed during hospital construction. We used European Organisation for the Research and Treatment of Cancer (EORTC) criterial diagnosis parameters for definition of IA.

FINDINGS

A total of 175 episodes of inpatient care were evaluated, 62 of which did not have any environmental control measures (when an outbreak occurred), and 113 that were subject to environmental control measures directed to preventing IA. The study showed an IA incidence of 25.8% for the group without environmental control measures vs 12.4% for those who did receive environmental control measures (P=0.024). The relative risk for IA was 0.595 (95% confidence interval: 0.394-0.897) for the group with environmental control measures.

CONCLUSION

The current study suggests that the implementation of environmental control measures during a hospital construction has a positive impact for prevention of IA in patients hospitalized with acute leukaemia.

Regulation of PD-L1 expression on murine tumor-associated monocytes and macrophages by locally produced TNF-α

PD-L1 is an immune checkpoint protein that has emerged as a major signaling molecule involved with tumor escape from T cell immune responses. Studies have shown that intra-tumoral expression of PD-L1 can inhibit antitumor immune responses. However, it has recently been shown that expression of PD-L1 on myeloid cells from the tumor is a stronger indicator of prognosis than tumor cell PD-L1 expression. Therefore, it is important to understand the factors that govern the regulation of PD-L1 expression on tumor-infiltrating myeloid cells. We found that immature bone marrow monocytes in tumor-bearing mice had low levels of PD-L1 expression, while higher levels of expression were observed on monocytes in circulation. In contrast, macrophages found in tumor tissues expressed much higher levels of PD-L1 than circulating monocytes, implying upregulation by the tumor microenvironment. We demonstrated that tumor-conditioned media strongly induced increased PD-L1 expression by bone marrow-derived monocytes and TNF-α to be a cytokine that causes an upregulation of PD-L1 expression by the monocytes. Furthermore, we found production of TNF-α by the monocytes themselves to be a TLR2-dependent response to versican secreted by tumor cells. Thus, PD-L1 expression by tumor macrophages appears to be regulated in a different manner than by tumor cells themselves.

Making the diagnosis, the tools, and risk stratification: More than just BCR-ABL

The implementation of cytogenetic and molecular techniques into standard clinical practice has improved our ability to more accurately diagnose and monitor CML. Routine peripheral blood BCR-ABL transcript testing can help monitor response, predict outcome, and detect early resistance or poor adherence to TKI therapy. The widely-used Sokal, Hasford and EUTOS clinical risk stratification scores were developed in patients receiving chemotherapy, interferon and imatinib, respectively; their predictive ability in patients receiving next-generation tyrosine kinase inhibitors (TKIs) remains to be established. Newer more sensitive molecular techniques are being developed that may aid in the expanding emphasis on discontinuing therapy in patients with a deep and consistent molecular response.

Wnt signaling inhibitor FH535 selectively inhibits cell proliferation and potentiates imatinib-induced apoptosis in myeloid leukemia cell lines

Wnt signaling pathway plays a major role in leukemogenesis of myeloid leukemia. Aberrancy in its regulation results in hyperactivity of the pathway contributing to leukemia propagation and maintenance. To investigate effects of Wnt pathway inhibition in leukemia, we used human leukemia cell lines (i.e., K562, HL60, THP1, and Jurkat) and several Wnt inhibitors, including XAV939, IWP2 and FH535. Our results showed that leukemia cell lines (>95 % cells) had increased endogenous levels of β-catenin as compared to mononuclear cells from healthy donors (0 %). Among the tested inhibitors, FH535 demonstrated a markedly suppressive effect (IC₅₀ = 358 nM) on mRNA levels of β-catenin target genes (LEF1, CCND1, and cMYC). In addition, FH535 significantly potentiated imatinib-induced apoptosis. Evaluation of erythrocyte and megakaryocyte lineage using flow cytometry demonstrated that the potentiation mechanism is independent of the developmental stage, and is more likely due to crosstalk between other pathways and β-catenin. FH535 also displayed antiproliferative properties in other cell lines used in this study. In summary, FH535 showed significantly high antiproliferative effects at submicromolar dosages, and additionally enhanced imatinib-induced apoptosis in human leukemia cell lines. Our results highlight its potential antileukemic promise when used in conjunction with other conventional therapeutic regimens.

Characterization of neutrophils and macrophages from ex vivo-cultured murine bone marrow for morphologic maturation and functional responses by imaging flow cytometry

Neutrophils and macrophages differentiate from common myeloid progenitors in the bone marrow, where they undergo nuclear morphologic changes during maturation. During this process, both cell types acquire critical innate immune functions that include phagocytosis of pathogens, and for neutrophils the release of nuclear material called nuclear extracellular traps (NETs). Primary cells used to study these functions are typically purified from mature mouse tissues, but bone marrow-derived ex vivo cultures provide more abundant numbers of progenitors and functionally mature cells. Routine analyses of these cells use conventional microscopy and flow cytometry, which present limitations; microscopy is laborious and subjective, whereas flow cytometry lacks spatial resolution. Here we describe methods to generate enriched populations of neutrophils or macrophages from cryopreserved mouse bone marrow cultured ex vivo, and to use imaging flow cytometry that combines the resolution of microscopy with flow cytometry to analyze cells for morphologic features, phagocytosis, and NETosis.

Survival from Acute MyeloidLeukaemia in Patients Over 55 Years of Age in Northern Ireland: A Discrete Population

Acute myeloid leukaemia is a disease of increasing frequency in the elderly. The aim of this study was to describe the survival and the factors influencing survival in a cohort older than 55 years in Northern Ireland, which has a relatively stable population. The median survival of the 92 cases identified in a 6-year period was 18 weeks with an actuarial survival overall at one year of 24%. Independent risk factors for survival were administration of chemotherapy with the intention to induce remission, social class 1 and 2, hepatomegaly, absence of splenomegaly, lower LDH, lower PB blast count, higher haemoglobin, female sex and WHO performance status 0-2. The results of this study suggest that survival from acute leukaemia in the elderly is very poor when an unselected patient cohort is considered.

Effect of chronic morphine administration on circulating dendritic cells in SIV-infected rhesus macaques

We studied the effect of chronic morphine administration on the circulating dendritic cell population dynamics associated with SIV infection using rhesus macaques. Animals were either first infected with SIV and then given chronic morphine, or visa versa. SIV infection increased the numbers of myeloid DCs (mDCs), but morphine treatment attenuated this mDC expansion. In contrast, morphine increased the numbers of plasmacytoid DCs (pDCs) in SIV-infected animals. Finally, chronic morphine administration (no SIV) transiently increased the numbers of circulating pDCs. These results show that chronic morphine induces a significant alteration in the available circulating levels of critical antigen-presenting cells.

Dendritic cells in renal biopsies of patients with acute tubulointerstitial nephritis

Dendritic cells (DCs) play a critical role in the regulation of the adaptive immune response and can be separated into 2 major subsets: myeloid (mDC) and plasmacytoid (pDC) DCs. Acute tubulointerstitial nephritis (ATIN) is a common cause of injury to renal tubules and interstitium resulting from the interplay of tubular cells and inflammatory cells and their products. However, the involvement of DCs in ATIN is still unknown. In this study, the participation and localization of myeloid (CD1c) and plasmacytoid (CD303) DC subsets in the biopsies from patients with ATIN (n=20), lupus nephritis (n=17, positive control), or minimal change disease (n=14, negative control) were investigated. DCs were identified morphologically within the tubulointerstitium in the renal biopsies by transmission electron microscopy interacting with surrounding tubules and inflammatory cells. Direct immunofluorescence showed that both CD1c+DCs and CD303+ DCs exist in all the renal biopsies. As compared with minimal change disease, biopsies with ATIN had significantly increased CD1c+DCs (P<.001) and CD303+ DCs (P<.001). The number of CD1c+DCs in ATIN was significantly higher than that in lupus nephritis (P<.02), whereas the number of CD303+ DCs in ATIN was slightly but not significantly higher than that in lupus nephritis (P=.2). DCs in the biopsies with ATIN were restricted to the tubulointerstitium forming dense networks, and most of them maintained immature state. All these findings suggest that DC subsets may be differentially involved in the pathogenesis of ATIN. Their potential role in intrarenal regulation of immune responses in ATIN is proposed.

The antiviral compound BIT225 inhibits HIV-1 replication in myeloid dendritic cells

Background

Previous studies with BIT225 (N-carbamimidoyl-5-(1-methyl-1H-pyrazol-4-yl)-2-naphthamide) have demonstrated a unique antiviral activity that blocks the release of HIV-1 from monocyte-derived macrophages (MDM). Antagonising the ion channel formed by HIV-1 Vpu, BIT225 preferentially targets de novo intracellular virus produced in ‘virus-containing compartments’ of MDM. In primary infections, dendritic cells (DC) are one of the first cells infected by HIV-1 and can transfer virus to more permissive CD4⁺ T cells, making these cells an important target for novel antiviral therapies. To extend previous findings with BIT225, we aimed to further characterise the antiviral activity of BIT225 on HIV-1 replication in monocyte-derived DC (MDDC).

Results

The anti-HIV-1 activity of BIT225 was evaluated in vitro within MDDC alone and in co-cultures with activated CD4⁺ T cells to examine the effect of the drug on HIV-1 transfer. Antiviral activity was determined by measuring HIV-1 reverse transcriptase activity in the culture supernatant of BIT225 treated and DMSO control cultures. A single dose of BIT225 resulted in a mean (SE) peak inhibition of HIV-1 release from MDDC by 74.5 % (±0.6) following 14 days of culture and a 6-fold reduction of HIV-1 transfer to activated uninfected CD4⁺ T cells in co-culture.

Conclusions

HIV-1 release from MDDC was inhibited by BIT225. This data broadens the drug’s antiviral activity profile within cells of the myeloid lineage. These findings suggest a potential role for BIT225 in reducing HIV-1 production and preventing viral dissemination in early and chronic infection and may assist in limiting virus spread with any ongoing viral replication during antiretroviral therapy.

Oral Azacitidine (CC-486) for the Treatment of Myelodysplastic Syndromes and Acute Myeloid Leukemia

The myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal myeloid malignancies characterized by multilineage cytopenias, recurrent cytogenetic abnormalities, and risk of progression to acute myeloid leukemia (AML). AML, which can occur de novo as well as secondary to MDS, is characterized by malignant clones of myeloid lineage in the bone marrow and peripheral blood, with dissemination into tissues. The cytidine nucleoside analog and epigenetic modifier azacitidine is approved in the U.S. for the treatment of all French-American-British subtypes of MDS and in many countries for the treatment of AML with 20%-30% blasts and multilineage dysplasia according to the World Health Organization classification. Benefits of azacitidine treatment of patients with AML with >30% blasts have also been shown in a recent phase III trial. Oral administration of azacitidine may enhance patient convenience, eliminate injection-site reactions, allow for alternative dosing and scheduling, and enable long-term treatment. Phase I studies with oral azacitidine (CC-486) have shown biological activity, clinical responses, and tolerability in patients with MDS and AML. Extended dosing schedules of oral azacitidine (for 14 or 21 days of 28-day cycles) are currently under investigation as frontline therapy in patients with lower risk MDS, as maintenance therapy for patients with AML not eligible for stem cell transplant, and as maintenance therapy for patients with MDS or AML following stem cell transplant. This review presents clinical data supporting the use of injectable azacitidine in MDS and AML and examines the rationale for and results of the clinical development of oral azacitidine.

Therapy-related acute myeloid leukemia following radioactive iodine treatment for thyroid cancer

BACKGROUND

Therapy-related acute myeloid leukemia (t-AML) associated with radioiodine treatment (RAI) is emerging as an important clinical entity with the rise in incidence of thyroid cancer.

DESIGN AND METHODS

We conducted an electronic search of MEDLINE and EMBASE, and also searched reference lists of articles and abstracts from conference proceedings for case reports and review articles on t-AML following radioiodine therapy. A total of 37 patients with acute myeloid neoplasms following radioiodine treatment were analyzed.

RESULTS

The median RAI dose was 324 mCi, and median age was 47.5 years with M/F ratio of 1:3. Latency period was 1-4 years, and the median time from RAI exposure to diagnosis of t-AML was 2.9 years. FAB M2 and M3 were the two most common t-AML subtypes reported. Seventy-one percent of the cases that reported cytogenetic abnormalities were classified as unfavorable. The most commonly reported abnormalities were del 5q and t(15:17). Survival outcomes were not reported due to lack of patient-level data.

CONCLUSIONS

T-AML following radioiodine therapy for thyroid cancer appears to have a shorter latency period than other types of t-AML, which is an important consideration for post-therapy surveillance. Reporting of cases and outcomes will help provide data for further research. Identifying biomarkers that help risk-stratify patients prior to therapy and specific genetic-guided therapies may help improve outcomes.

Oral Maintenance Chemotherapy with 6-Mercaptopurine and Methotrexate in Patients with Acute Myeloid Leukemia Ineligible for Transplantation

For decades, maintenance chemotherapy has failed to improve the cure rate or prolong the survival of patients with acute myeloid leukemia (AML), other than those with acute promyelocytic leukemia. Immediately after the first complete remission following consolidation therapy was obtained, oral maintenance chemotherapy (daily 6-mercaptopurine and weekly methotrexate) was given and continued for two years in transplant-ineligible AML patients. Leukemia-free survival (LFS) and overall survival (OS) were studied and compared between these patients and the historical control group who did not receive maintenance therapy. Consecutive 52 transplant-ineligible AML patients were analyzed. Among these patients, 27 received oral maintenance chemotherapy. No significant difference was found in the patients' characteristics between the maintenance and the control groups. The median OS was 43 (95% CI, 19-67) and 19 (95% CI, 8-30) months in the maintenance and the control groups, respectively (P = 0.202). In the multivariate analysis, the presence of maintenance therapy was an independent prognostic factor for better OS (P = 0.021) and LFS (P = 0.024). Clinical benefit from maintenance chemotherapy was remarkable in older patients (≥ 60 yr) (P = 0.035), those with intermediate or unfavorable cytogenetics (P = 0.006), those with initial low blast count in peripheral blood (P = 0.044), and those receiving less than two cycles of consolidation therapy (P = 0.017). Maintenance oral chemotherapy as a post-remission therapy can prolong the survival of patients with AML who are not eligible for transplantation, particularly older patients, those with intermediate or unfavorable cytogenetics, those with initial low blast count, and those receiving less than two cycles of consolidation therapy.

B-acute lymphoblastic leukemia/lymphoblastic lymphoma

OBJECTIVES

This session of the 2013 Society of Hematopathology/European Association for Haematopathology Workshop was dedicated to B-acute lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (LBL) with recurrent translocations and not otherwise specified.

METHODS

In this review, we summarize the cases discussed during the workshop, review the pertinent and most recent literature on the respective topics, and provide a few key points that may aid in the workup of patients with B-ALL/LBL.

RESULTS

Many of the submitted cases showed interesting diagnostic, immunophenotypic, or clinical aspects of B-ALL with BCR/ABL1, MLL-associated, and other recurrent chromosomal abnormalities. Several cases showed rare aberrancies such as coexistent IGH/BCL2 and MYC rearrangements and raised issues in classification. Other cases had unusual clinical presentations, including B-ALL with hypereosinophilia and therapy-related B-ALL. Several cases highlighted the role of flow cytometry immunophenotyping in distinguishing benign B-cell precursors from aberrant lymphoblasts, and other cases raised questions regarding the clinical importance of myeloperoxidase positivity in acute lymphoblastic leukemia.

CONCLUSIONS

The complexity and spectrum of cases presented in this review highlight the importance of clinicopathologic correlation and the value of ancillary studies in the classification and workup of patients with B-ALL/LBL.

Acute leukemias of ambiguous origin

OBJECTIVES

This session of the Society for Hematopathology/European Association for Haematopathology Workshop focused on acute leukemias of ambiguous origin.

METHODS

We provide an overview of mixed-phenotype acute leukemia (MPAL) as recognized in the current World Health Organization classification and summarize diagnostic criteria for major categories of MPAL: B/myeloid, T/myeloid, B/T, and B/T/myeloid.

RESULTS

Most MPAL cases submitted were B/myeloid and T/myeloid MPAL, the most frequent types, but three cases of B/T MPAL were also submitted, and examples of all categories are illustrated. We emphasize that a comprehensive approach to immunophenotyping is required to accurately establish the diagnosis of MPAL. Flow cytometry immunophenotyping using a large panel of antibodies is needed as well as confirmatory immunohistochemical analysis and cytochemistry studies for myeloperoxidase and nonspecific esterase. We discuss technical issues in determining blast lineage and possible pitfalls in MPAL diagnosis. In particular, rare cases of B-acute lymphoblastic leukemia (B-ALL) can express myeloperoxidase but are otherwise consistent with B-ALL and should be treated as such. Last, we review the differential diagnosis between acute undifferentiated leukemia and acute myeloid leukemia with minimal differentiation.

CONCLUSIONS

There was an agreement that diagnosis of MPAL can be challenging, especially if applied flow cytometry panels are not comprehensive enough.

Differential Diagnosis of Isolated Myeloid Sarcoma: A Case Report and Review of the Literature

Myeloid sarcoma (MS) is a rare disease entity identified as a variety of manifestations defined by the occurrence of extramedullary myeloid cell masses with or without bone marrow involvement. This case describes an unusual presentation of isolated MS in a 60-year-old otherwise healthy male, who initially presented to his primary care physician with vague abdominal pain. After extensive workup including three omental biopsies, umbilical core biopsy, and inguinal lymph node biopsy, he was ultimately diagnosed with isolated MS with extensive extramedullary tumor burden. Despite advanced extramedullary disease, peripheral cell counts were normal and bilateral bone marrow biopsies unremarkable with normal cellular lineages, morphology, and cytogenetics. The patient underwent induction chemotherapy and is now greater than 100 days post myeloablative unrelated donor marrow transplantation with no evidence of disease recurrence and 100% donor status with full chimerism. This case demonstrates that making a prompt diagnosis with rapid initiation of treatment in myeloid sarcoma can be challenging due to its varied clinical presentation, cytomorphology, cytochemistry, and cytogenetic overlap with other lymphoid malignancies. Once a diagnosis of MS has been made, moving quickly to induction therapy is important. Several studies have shown that improved overall survival is attained when MS is treated as acute myeloid leukemia and increased survival is noted for patients undergoing bone marrow transplantation. Further prospective studies are needed to elucidate the many remaining questions in regards to the natural history, prognosis, and optimal treatment strategies for this deadly disease.

Tyrosine kinase inhibitors in patients with chronic myelogeneous leukemia: defining the role of social risk factors and non-adherence to treatment

OBJECTIVE

To assess the role of social risk factors on adherence to tyrosine kinase inhibitors (TKI) therapy in chronic myeloid leukemia (CML) patients.

METHODS

This is a retrospective study and eligible patients were adults with CML on TKI treatment. Cases of no adherence to treatment were confirmed during pharmacists' consultation (patient-reported adherence). Baseline characteristics between groups were compared between cases and controls groups. Risk factors identified in bivariate analysis (p<0.2) were included in multivariate model. A qualitative investigation assessed whether such predictors of non-adherence had causal relationship.

RESULTS

Of 151 patients with CML consulted by pharmacists, 21% had adherence problems. Despite patients with secondary school (p=0.03), most of investigated social risk factors did not differ between groups. However, by using a qualitative approach, patients' level of education could not explain low adherence rates behavior.

CONCLUSIONS

Social determinants of health, herein investigated, were unlikely to predict adherence to treatment. Regression techniques may lead to untrue statements, so future researches should consider investigating the causes, not only the statistical estimates.

A diffusible signal derived from hematopoietic cells supports the survival and proliferation of regenerative cells during zebrafish fin fold regeneration

Multicellular organisms maintain body integrity by constantly regenerating tissues throughout their lives; however, the overall mechanism for regulating regeneration remains an open question. Studies of limb and fin regeneration in teleost fish and urodeles have shown the involvement of a number of locally activated signals at the wounded site during regeneration. Here, we demonstrate that a diffusible signal from a distance also play an essential role for regeneration. Among a number of zebrafish mutants, we found that the zebrafish cloche (clo) and tal1 mutants, which lack most hematopoietic tissues, displayed a unique regeneration defect accompanying apoptosis in primed regenerative tissue. Our analyses of the mutants showed that the cells in the primed regenerative tissue are susceptible to apoptosis, but their survival is normally supported by the presence of hematopoietic tissues, mainly the myeloid cells. We further showed that a diffusible factor in the wild-type body fluid mediates this signal. Thus, our study revealed a novel mechanism that the hematopoietic tissues regulate tissue regeneration through a diffusible signal.

Red cell antigen loss in a patient with chronic myeloid leukemia: a case of ABO discrepancy

Change in ABO antigen expression on the surface of neoplastic cells have been seen for a variety of tumor types. This phenomenon has been linked with myeloid neoplasms as well but is reported infrequently. Here, we report a rare cause of ABO discrepancy in an elderly female having chronic myeloid leukemia.

Lysosomal drug sequestration as a mechanism of drug resistance in vascular sarcoma cells marked by high CSF-1R expression

Background

Human angiosarcoma and canine hemangiosarcoma are thought to arise from vascular tissue or vascular forming cells based upon their histological appearance. However, recent evidence indicates a hematopoietic or angioblastic cell of origin for these tumors. In support of this idea, we previously identified an endothelial-myeloid progenitor cell population with high expression of endothelial cell markers and the myeloid cell marker, colony stimulating factor 1 receptor (CSF-1R). Here, we further characterized these cells to better understand how their cellular characteristics may impact current therapeutic applications.

Methods

We performed cell enrichment studies from canine hemangiosarcoma and human angiosarcoma cell lines to generate cell populations with high or low CSF-1R expression. We then utilized flow cytometry, side population and cell viability assays, and fluorescence based approaches to elucidate drug resistance mechanisms and to determine the expression of hematopoietic and endothelial progenitor cell markers.

Results

We demonstrated that cells with high CSF-1R expression enriched from hemangiosarcoma and angiosarcoma cell lines are more drug resistant than cells with little or no CSF-1R expression. We determined that the increased drug resistance may be due to increased ABC transporter expression in hemangiosarcoma and increased drug sequestration within cellular lysosomes in both hemangiosarcoma and angiosarcoma.

Conclusions

We identified drug sequestration within cellular lysosomes as a shared drug resistance mechanism in human and canine vascular sarcomas marked by high CSF-1R expression. Taken together, our results demonstrate that studies in highly prevalent canine hemangiosarcoma may be especially relevant to understanding and addressing drug resistance mechanisms in both the canine and human forms of this disease.