An Extended Flow Cytometry Evaluation of ex Vivo Expanded NK Cells Using K562.Clone1, a Feeder Cell Line Manufactured in Brazil.

Natural killer (NK) cells play a crucial role in the immune system's response against cancer. However, the challenge of obtaining the required quantity of NK cells for effective therapeutic response necessitates the development of strategies for their ex vivo expansion. This study aimed to develop a novel feeder cell line, K562.Clone1, capable of promoting the ex vivo expansion of NK cells while preserving their cytotoxic potential. he K562 leukemic cell line was transduced with mbIL-21 and 4-1BBL proteins to generate K562.Clone1 cells. NK cells were then co-cultured with these feeder cells, and their expansion rate was monitored over 14 days. The cytotoxic potential of the expanded NK cells was evaluated against acute myeloid leukemia blasts and tumor cell lines of leukemia and glial origin. Statistical analysis was performed to determine the significance of the results. The K562.Clone1 co-cultured with peripheral NK showed a significant increase in cell count, with an approximate 94-fold expansion over 14 days. Expanded NK cells demonstrated cytotoxicity against the tested tumor cell lines, indicating preservation of their cytotoxic characteristics. Additionally, the CD56, CD16, inhibitory KIRs, and activation receptors were conserved and present in a well-balanced manner. The study successfully developed a feeder cell line, K562.Clone1, that effectively promotes the expansion of NK cells ex vivo while maintaining their cytotoxic potential. This development could significantly contribute to the advancement of NK cell therapy, especially in Brazil.

Molecular Characterization of a First-in-Human Clinical Response to Nimesulide in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is a hematologic malignancy associated with high morbidity and mortality. Here we describe a case of a patient with AML who presented a partial response after utilization of the non-steroidal anti-inflammatory drug nimesulide. The response was characterized by complete clearance of peripheral blood blasts and an 82% decrease of bone marrow blasts associated with myeloblast differentiation. We have then shown that nimesulide induces in vitro cell death and cell cycle arrest in all AML cell lines (HL-60, THP-1, OCI-AML2, and OCI-AML3). Weighted Correlation Network Analysis (WGCNA) of serial whole-transcriptome data of cell lines treated with nimesulide revealed that the sets of genes upregulated after treatment with nimesulide were enriched for genes associated with autophagy and apoptosis, and on the other hand, the sets of downregulated genes were associated with cell cycle and RNA splicing. Serial transcriptome of bone marrow patient sample confirmed the upregulation of genes associated with autophagy after the response to nimesulide. Lastly, we demonstrated that nimesulide potentiates the cytotoxic in vitro effect of several Food and Drug Administration (FDA)-approved chemotherapy drugs used in AML, including cytarabine.

Prognostic impact of RAS-pathway mutations in patients with myelofibrosis.

RAS-pathway mutations are recurrent events in myeloid malignancies. However, there is limited data on the significance of RAS-pathway mutations in patients with myelofibrosis (MF). We analyzed next-generation sequencing data of 16 genes, including RAS-pathway genes, from 723 patients with primary and secondary MF across three international centers and evaluated their significance. N/KRAS variants were present in 6% of patients and were typically sub-clonal (median VAF = 20%) relative to other genes variants. RAS variants were associated with advanced MF features including leukocytosis (p = 0.02), high somatic mutation burden (p < 0.01) and the presence of established "molecular high-risk" (MHR) mutations. MF patients with N/KRAS mutations had shorter 3-year overall survival (OS) (34% vs 58%, p < 0.001) and higher incidence of acute myeloid leukemia at 3 years (18% vs 11%, p = 0.03). In a multivariate Cox model, RAS mutations were associated with decreased OS (HR 1.93, p < 0.001). We created a novel score to predict OS incorporating RAS mutations, and it predicted OS across training and validation cohorts. Patients with intermediate risk/high-risk DIPSS with RAS mutations who received ruxolitinib had a nonsignificant longer 2-year OS relative to those who did not receive ruxolitinib. These data demonstrate the importance of identifying RAS mutations in MF patients.

Challenges and opportunities in primary CNS lymphoma: A systematic review.

BACKGROUND: Historically, high-dose methotrexate (HD-MTX) plus consolidation chemotherapy and/or whole brain radiotherapy (WBRT) has been the gold standard on Primary Central Nervous System Lymphoma (PCNSL) management. We sought to examine and summarize the data, on clinical trial (CT) setting, investigating multi-modality treatment to PCNSL. METHODS: We performed a systematic review of electronic databases (Medline, EMBASE, Cochrane Database and clinicaltrials.gov) and a manual search to identify original PCNSL phase 2 and phase 3 CT from the last 10years. After a 4stage Prisma based selection process, 32 published (3 Randomized CT and 29 phases 2 CT) studies ultimately were selected for review. Four ongoing clinical trials found on clinicaltrial.gov were reviewed. Two investigators reviewed titles, abstracts, and articles independently. Two investigators abstracted data sequentially and evaluated each study independently. FINDINGS: Treatment of PCNSL requires a multidisciplinary approach. HD-MTX represents the most accepted standard of care induction therapy for newly diagnosed PCNSL. When HD-MTX is given with WBRT for consolidation delayed neurotoxicity can be an important complication, particularly in elderly patients. Studies have suggested that WBRT may be deferred until relapse without compromising survival and deferring WBRT may be the best approach in elderly patients. Results from dose-reduced WBRT and consolidative HD-Ara-C are encouraging. High-dose chemotherapy in combination with autologous stem cell transplantation (HDC-ASCT) as chemotherapy alone has emerged as an important consolidative treatment for selected population. The optimal salvage therapy is still to be defined. CONCLUSION: WBRT for consolidation is a well-studied modality; however emerging options to selected population such as HDC-ASCT, dose-reduced WBRT or chemotherapy alone are associated with similar survival outcome and less neurotoxicity in selected series. Ongoing and future clinical trials will better define the best approach on this rare disease.

Endoscopic combined "transseptal/transnasal" approach for pituitary adenoma: reconstruction of skull base using pedicled nasoseptal flap in 91 consecutive cases.

OBJECTIVE: The purpose of this study was to describe the endoscopic combined "transseptal/transnasal" approach with a pedicled nasoseptal flap for pituitary adenoma and skull base reconstruction, especially with respect to cerebrospinal fluid (CSF) fistula. METHOD: Ninety-one consecutive patients with pituitary adenomas were retrospectively reviewed. All patients underwent the endoscopic combined "transseptal/transnasal" approach by the single team including the otorhinolaryngologists and neurosurgeons. Postoperative complications related to the flap were analyzed. RESULTS: Intra- and postoperative CSF fistulae were observed in 36 (40%) and 4 (4.4%) patients, respectively. Among the 4 patients, lumbar drainage and bed rest healed the CSF fistula in 3 patients and reoperation for revision was necessary in one patient. Other flap-related complications included nasal bleeding in 3 patients (3.3%). CONCLUSION: The endoscopic combined "transseptal/transnasal" approach is most suitable for a two-surgeon technique and a pedicled nasoseptal flap is a reliable technique for preventing postoperative CSF fistula in pituitary surgery.

Endoscopic combined “transseptal/transnasal” approach for pituitary adenoma: reconstruction of skull base using pedicled nasoseptal flap in 91 consecutive cases / O acesso endoscópico transeptal/transnasal em cirurgias de resseção de adenoma de hipófise: reconstrução da base do crânio combinado com a criação do flap naso-septal pediculado em 91 pacientes consecutivos

Objective The purpose of this study was to describe the endoscopic combined “transseptal/transnasal” approach with a pedicled nasoseptal flap for pituitary adenoma and skull base reconstruction, especially with respect to cerebrospinal fluid (CSF) fistula.Method Ninety-one consecutive patients with pituitary adenomas were retrospectively reviewed. All patients underwent the endoscopic combined “transseptal/transnasal” approach by the single team including the otorhinolaryngologists and neurosurgeons. Postoperative complications related to the flap were analyzed.Results Intra- and postoperative CSF fistulae were observed in 36 (40%) and 4 (4.4%) patients, respectively. Among the 4 patients, lumbar drainage and bed rest healed the CSF fistula in 3 patients and reoperation for revision was necessary in one patient. Other flap-related complications included nasal bleeding in 3 patients (3.3%).Conclusion The endoscopic combined “transseptal/transnasal” approach is most suitable for a two-surgeon technique and a pedicled nasoseptal flap is a reliable technique for preventing postoperative CSF fistula in pituitary surgery.

Objetivo O objetivo deste estudo foi descrever o acesso endoscópico transeptal/transnasal combinado com a criação do flap naso-septal pediculado para reconstrução da base do crânio em cirurgias de resseção de adenoma de hipófise, especialmente nos casos que ocorrem fístula líquido cefalorraquidiano (FLC).Método Noventa e um pacientes consecutivos portadores de adenoma de hipófise foram retrospectivamente revisados. Complicações pós-operatórias relacionadas ao flap foram analisadas.Resultados Fístulas líquido cefalorraquidiano intra e pós-operatórias foram observadas em 36 (40%) e 4 (4,4%) dos pacientes, respectivamente. Entre os 4 pacientes, drenagem lombar e repouso absoluto foram suficientes para o fechamento da fístula e intervenção cirúrgica foi necessária em apenas um paciente. Outra complicação relacionada ao flap foi o sangramento em 3 (3,3%) dos pacientes.Conclusão O acesso endoscópico transeptal/transnasal combinado é melhor aplicado quando realizado por dois cirurgiões e o flap naso-septal é uma técnica eficaz para prevenção de fístula pós-operatória em cirurgias de hipófise.

The PGE2/IL-10 Axis Determines Susceptibility of B-1 Cell-Derived Phagocytes (B-1CDP) to Leishmania major Infection.

B-1 cells can be differentiated from B-2 cells because they are predominantly located in the peritoneal and pleural cavities and have distinct phenotypic patterns and activation properties. A mononuclear phagocyte derived from B-1 cells (B-1CDP) has been described. As the B-1CDP cells migrate to inflammatory/infectious sites and exhibit phagocytic capacity, the microbicidal ability of these cells was investigated using the Leishmania major infection model in vitro. The data obtained in this study demonstrate that B-1CDP cells are more susceptible to infection than peritoneal macrophages, since B-1CDP cells have a higher number of intracellular amastigotes forms and consequently release a larger number of promastigotes. Exacerbated infection by L. major required lipid bodies/PGE2 and IL-10 by B-1CDP cells. Both infection and the production of IL-10 were decreased when PGE2 production was blocked by NSAIDs. The involvement of IL-10 in this mechanism was confirmed, since B-1CDP cells from IL-10 KO mice are more competent to control L. major infection than cells from wild type mice. These findings further characterize the B-1CDP cells as an important mononuclear phagocyte that plays a previously unrecognized role in host responses to L. major infection, most likely via PGE2-driven production of IL-10.

Efficacy of ruxolitinib for myelofibrosis.

INTRODUCTION: The discovery of the activating JAK2 V617F mutation in patients with myelofibrosis (MF) led to the development of JAK2 inhibitors. The first such inhibitor to enter clinical trials was ruxolitinib . This review summarizes preclinical and clinical data of ruxolitinib in MF. AREAS COVERED: A literature search through Medline employing the terms 'ruxolitinib,' 'INCB018424' and 'myelofibrosis' was undertaken. The results from Phase I/II studies in patients with MF showed that ruxolitinib led to durable improvements in splenomegaly, and symptoms associated with MF. Two Phase III trials have compared ruxolitinib against placebo and best available therapy, and in both studies ruxolitinib demonstrated superior rates of spleen control and symptom improvement, and additional analysis demonstrated a survival benefit with ruxolitinib treatment. The main toxicities seen with ruxolitinib are cytopenias, which are managed with dose adjustments. Recent reports documented sporadic cases of immunosuppression-related infections. Ruxolitinib is the first drug ever approved for the therapy of patients with MF. EXPERT OPINION: Understanding the factors that predict the rate and duration of response to ruxolitinib would improve our ability to manage patients treated with this medication. Clinical trials combining ruxolitinib with novel compounds that are also active in MF will further improve therapy for this disease.

Splenectomy in patients with myeloproliferative neoplasms: efficacy, complications and impact on survival and transformation.

Splenectomy may be an effective therapeutic option for treating massive splenomegaly in patients with myeloproliferative neoplasms (MPNs). There are still limited data on its short- and long-term benefits and risks. Efficacy and short-term complications were analyzed in 94 patients with different MPNs who underwent splenectomy at M. D. Anderson Cancer Center. The long-term impact of splenectomy on overall survival (OS) and transformation free survival (TFS) was evaluated in 461 patients with myelofibrosis (MF) seen at M. D. Anderson, including 50 who underwent splenectomy during disease evolution. Splenectomy improved anemia and thrombocytopenia in 47% and 66% of patients, respectively. The most common complications were leukocytosis (76%), thrombocytosis (43%) and venous thromboembolism (16%). Post-operative mortality was 5%. Among patients with MF, splenectomy during disease evolution was associated with decreased OS (hazard ratio [HR] = 2.17, p < 0.0001) and TFS (HR = 2.17, p < 0.0001). This effect was independent of the Dynamic International Prognostic Scoring System. Splenectomy is a possible therapeutic option for patients with MF and other MPNs, and its greatest benefits are related to improvement in spleen pain and discomfort, anemia and thrombocytopenia. However, in patients with MF it appears to be associated with increased mortality.

What is next beyond janus kinase 2 inhibitors for primary myelofibrosis?

PURPOSE OF REVIEW: Although the approval of the janus kinase (JAK) inhibitor ruxolitinib for therapy of patients with myelofibrosis represents an important step in the development of targeted therapy for these patients, JAK inhibitors do not eradicate the disease, and a review of novel agents with mechanisms of action complementary to JAK2 enzymatic inhibition is timely. RECENT FINDINGS: There are several compounds with different mechanisms of action undergoing preclinical and clinical testing in myelofibrosis. Heat shock protein inhibitors and histone deacetylase inhibitors induce JAK2 degradation and downregulation of intracellular oncogenic signalling, and may overcome resistance to JAK2 inhibitors. Reversal of bone marrow fibrosis is still a therapeutic challenge in this disease, and mAbs targeting transforming growth factor-ß and lysyl oxidase like-2 may prove efficacious. Promising compounds inhibiting signal transducer and activator of transcription 5 activity and inducing megakaryocyte polyploidization are in preclinical testing. SUMMARY: Although none of these new drugs have been approved for therapy of myelofibrosis, their activity is being tested in clinical trials, alone or in combination with JAK2 inhibitors. Patients with myelofibrosis should be encouraged to participate in clinical trials testing novel compounds for this disorder, particularly if they have failed a trial of JAK2 inhibitors.

Small lymphocytic lymphoma and chronic lymphocytic leukemia: are they the same disease?

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world, characterized by peripheral blood B-cell lymphocytosis as well as lymphadenopathy, organomegaly, cytopenias, and systemic symptoms. Chronic lymphocytic leukemia cells have a distinctive immunophenotype, and the disease has a characteristic pattern of histological infiltration in the lymph node and bone marrow. The clinical course of CLL is heterogeneous, with some patients presenting with very indolent disease and other patients having a more aggressive malignancy. It is known that genetic abnormalities underlie this difference in clinical presentation. Some patients may present solely with lymphadenopathy, organomegaly, and presence of infiltrating monoclonal B cells with the same immunophenotype as CLL cells, but lacking peripheral blood lymphocytosis. This disease is called small lymphocytic lymphoma (SLL) and has been considered for almost 2 decades to be the tissue equivalent of CLL. Both CLL and SLL are currently considered different manifestations of the same entity by the fourth edition of the World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. It is suspected that differential expression of chemokine receptors (e.g., reduced expression of R1 and CCR3 in SLL cells), integrins (e.g., CLL cells have lower expression of integrin αLß2), and genetic abnormalities (a higher incidence of trisomy 12 and lower incidence of del(13q) is found in SLL) may explain some of the clinical differences between these 2 disorders. However, there is still a lack of knowledge on the precise biological basis underlying the different clinical presentations of CLL and SLL. It is expected that future studies will shed light on the pathophysiology of both disorders.

Dasatinib for the treatment of Philadelphia chromosome-positive leukemias.

INTRODUCTION: Dasatinib is a dual Abl/Src tyrosine kinase inhibitor (TKI), which was developed to treat patients with chronic myelogenous leukemia (CML), who had failed or were intolerant to therapy with imatinib. AREAS COVERED: In this article, we review preclinical and clinical studies with dasatinib for the therapy of Philadelphia (Ph)-positive leukemias. EXPERT OPINION: Dasatinib is very effective in the setting of CML resistance or intolerance to imatinib, particularly in patients in chronic phase (CP). Dasatinib is also effective against most BCR-ABL1 mutations that arise during therapy with imatinib. Further studies have confirmed activity of dasatinib as a single-agent, and combined with chemotherapy, for the treatment of patients with Philadelphia-positive acute lymphoblastic leukemia (Ph+-ALL). More recently, randomized trials have demonstrated that dasatinib is superior to imatinib in the initial therapy of patients with CML, and the drug was approved by the FDA for this indication in 2011.

Therapy with JAK2 inhibitors for myeloproliferative neoplasms.

The development of JAK2 inhibitors followed the discovery of activating mutation of JAK2 (JAK2V617F) in patients with classic Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPN). It is now known that mutations activating the JAK-STAT pathway are ubiquitous in Ph-negative MPN, and that the deregulated JAK-STAT pathway plays a central role in the pathogenesis of these disorders. JAK2 inhibitors thus are effective in patients both with and without the JAK2V617F mutation. This article reviews the rationale for using JAK2 inhibitors in Ph-negative MPN, and the results of more recent clinical trials with these drugs.

JAK2 inhibitors for myelofibrosis: why are they effective in patients with and without JAK2V617F mutation?

An activating mutation (V617F) in the pseudokinase domain of the Janus kinase (JAK)-2 tyrosine kinase has been described in 90% of patients with polycythemia vera (PV) and 50% of patients with essential thrombocythemia (ET) and primary myelofibrosis (MF). The discovery of JAK2V617F stirred the development of JAK2 inhibitors for treatment of patients with MF, ET and PV. Similar to other tyrosine kinase (TK) inhibitors in current use, JAK2 inhibitors target the adenosine triphosphate (ATP) binding site at the TK domain and not the pseudokinase domain, thus affecting both mutated and wild-type kinases. In fact, clinical trials of these compounds have demonstrated improvements in constitutional symptoms and splenomegaly in patients with both mutated and wild-type JAK2 MF. It is believed that these drugs may act not only through inhibition of neoplastic cell proliferation, but also by downregulating signaling through proinflammatory cytokine receptors. In this article, we review the current state of JAK2 inhibitors and discuss why these drugs could be a valuable addition to the treatment armamentarium for patients with and without the JAK2V617F mutation.

Membrane cholesterol regulates lysosome-plasma membrane fusion events and modulates Trypanosoma cruzi invasion of host cells.

BACKGROUND: Trypomastigotes of Trypanosoma cruzi are able to invade several types of non-phagocytic cells through a lysosomal dependent mechanism. It has been shown that, during invasion, parasites trigger host cell lysosome exocytosis, which initially occurs at the parasite-host contact site. Acid sphingomyelinase released from lysosomes then induces endocytosis and parasite internalization. Lysosomes continue to fuse with the newly formed parasitophorous vacuole until the parasite is completely enclosed by lysosomal membrane, a process indispensable for a stable infection. Previous work has shown that host membrane cholesterol is also important for the T. cruzi invasion process in both professional (macrophages) and non-professional (epithelial) phagocytic cells. However, the mechanism by which cholesterol-enriched microdomains participate in this process has remained unclear. METHODOLOGY/PRINCIPAL FINDING: In the present work we show that cardiomyocytes treated with MßCD, a drug able to sequester cholesterol from cell membranes, leads to a 50% reduction in invasion by T. cruzi trypomastigotes, as well as a decrease in the number of recently internalized parasites co-localizing with lysosomal markers. Cholesterol depletion from host membranes was accompanied by a decrease in the labeling of host membrane lipid rafts, as well as excessive lysosome exocytic events during the earlier stages of treatment. Precocious lysosomal exocytosis in MßCD treated cells led to a change in lysosomal distribution, with a reduction in the number of these organelles at the cell periphery, and probably compromises the intracellular pool of lysosomes necessary for T. cruzi invasion. CONCLUSION/SIGNIFICANCE: Based on these results, we propose that cholesterol depletion leads to unregulated exocytic events, reducing lysosome availability at the cell cortex and consequently compromise T. cruzi entry into host cells. The results also suggest that two different pools of lysosomes are available in the cell and that cholesterol depletion may modulate the fusion of pre-docked lysosomes at the cell cortex.

Breakthroughs in myeloproliferative neoplasms.

The discovery of the JAK2V617F mutation ushered the field of Philadelphia-negative myeloproliferative neoplasms (MPNs) into the era of targeted therapy. Currently, there are several JAK2 inhibitors in clinical trials for patients with MPNs, particularly for patients with myelofibrosis (MF). These drugs act by blocking the proliferation of neoplastic cells by disrupting the JAK2-STAT signaling and by abrogating inflammatory cytokine signaling which is dependent on JAK kinases. Therapy with JAK2 inhibitors can improve splenomegaly and debilitating constitutional symptoms in great majority of MF patients, improving greatly their quality of life. Long-term follow-up will reveal whether these drugs can also prolong survival by better controlling signs and symptoms of the MF. There are other compounds in clinical trials for MPNs, including the new immunomodulatory drug pomalidomide, and inhibitor of mammalian target of Rapamycin everolimus. In this article, we briefly review the latest therapeutic advances in the field of Philadelphia-negative MPNs.

Evolution of therapies for chronic myelogenous leukemia.

The clinical outcome for patients with chronic myelogenous leukemia (CML) has changed dramatically in the past 15 years. This has been due to the development of tyrosine kinase inhibitors (TKIs), compounds that inhibit the activity of the oncogenic BCR-ABL1 protein. Imatinib was the first TKI developed for CML, and it led to high rates of complete cytogenetic responses and improved survival for patients with this disease. However, approximately 35% of patients in chronic phase treated with imatinib will develop resistance or intolerance to this drug. The recognition of the problem of imatinib failure led to the design of second-generation TKI (dasatinib, nilotinib, and bosutinib). These drugs are highly active in the scenario of imatinib resistance or intolerance. More recently, both nilotinib and dasatinib were approved for frontline use in patients with chronic phase CML. Ponatinib represents the last generation of TKI, and this drug has been developed with the aim of targeting a specific BCR-ABL1 mutation (T315I), which arises in the setting of prolonged TKI therapy and leads to resistance to all commercially available TKI. Parallel to the development of specific drugs for treating CML, major advances were made in the field of disease monitoring and standardization of response criteria. In this review, we summarize how therapy with TKI for CML has evolved during the last decade.

JAK2 inhibitors: are they the solution?

The discovery of the JAK2V617F mutation in patients with Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPN) started the era of targeted therapy for these diseases. Until now, patients had few treatment options available, which usually were restricted to hydroxyurea, interferon preparations, and chemotherapy in more aggressive cases. JAK2 inhibitors have been developed over the past 5 years, and the results of the first clinical trials with JAK2 inhibitors for patients with myelofibrosis were recently published. Current research results suggest that JAK2 inhibitors have a potential to decrease disease burden and its activity, as manifested by a decrease in splenomegaly and improvement in systemic disease-related symptoms, but they do not seem to be able to eradicate the malignant clone. However, JAK2 inhibitors help patients regardless of their mutation status, because patients without JAK2V617F mutation benefit to the same extent as patients with JAK2V617F mutation. A greater understanding of the pathophysiology of MPNs is needed before we can cure myelofibrosis with drug therapy. Currently, several new JAK2 inhibitors are in clinical trials for patients with myelofibrosis, and clinical trials for patients with polycythemia vera and essential thrombocythemia have also started. We review recent data on JAK2 inhibitors for the management of patients with Ph-negative MPNs.

Eosinophils as a novel cell source of prostaglandin D2: autocrine role in allergic inflammation.

PGD(2) is a key mediator of allergic inflammatory diseases that is mainly synthesized by mast cells, which constitutively express high levels of the terminal enzyme involved in PGD(2) synthesis, the hematopoietic PGD synthase (H-PGDS). In this study, we investigated whether eosinophils are also able to synthesize, and therefore, supply biologically active PGD(2). PGD(2) synthesis was evaluated within human blood eosinophils, in vitro differentiated mouse eosinophils, and eosinophils infiltrating inflammatory site of mouse allergic reaction. Biological function of eosinophil-derived PGD(2) was studied by employing inhibitors of synthesis and activity. Constitutive expression of H-PGDS was found within nonstimulated human circulating eosinophils. Acute stimulation of human eosinophils with A23187 (0.1-5 µM) evoked PGD(2) synthesis, which was located at the nuclear envelope and was inhibited by pretreatment with HQL-79 (10 µM), a specific H-PGDS inhibitor. Prestimulation of human eosinophils with arachidonic acid (10 µM) or human eotaxin (6 nM) also enhanced HQL-79-sensitive PGD(2) synthesis, which, by acting on membrane-expressed specific receptors (D prostanoid receptors 1 and 2), displayed an autocrine/paracrine ability to trigger leukotriene C(4) synthesis and lipid body biogenesis, hallmark events of eosinophil activation. In vitro differentiated mouse eosinophils also synthesized paracrine/autocrine active PGD(2) in response to arachidonic acid stimulation. In vivo, at late time point of the allergic reaction, infiltrating eosinophils found at the inflammatory site appeared as an auxiliary PGD(2)-synthesizing cell population. Our findings reveal that eosinophils are indeed able to synthesize and secrete PGD(2), hence representing during allergic inflammation an extra cell source of PGD(2), which functions as an autocrine signal for eosinophil activation.

New drugs for chronic myelogenous leukemia.

The introduction of tyrosine kinase inhibitors (TKIs) has changed the landscape of therapy for chronic myelogenous leukemia (CML). Once considered an incurable malignancy, CML now has become a manageable chronic condition. Despite the great advances that imatinib has brought to the treatment of CML, some patients still develop resistance to imatinib and other TKIs, such as dasatinib and nilotinib. Furthermore, none of the clinically available TKIs is capable of eradicating leukemia stem cells and therefore curing CML. Several new compounds have been developed in recent years in an attempt to manage TKI-resistant CML. These include third-generation TKIs (ponatinib, danusertib) and even old compounds such as omacetaxine, which were developed before imatinib and now find a possible niche in the treatment of imatinib-resistant CML. We review the current preclinical and clinical data on the most promising new compounds for the treatment of CML.