fedratinib and Disease-Models--Animal

Myeloproliferative neoplasms (MPNs) are diseases that carry the JAK2 (V617F) mutation in about 70% of the patients. The purpose of this review is to describe the recent advances in the therapy of MPNs with JAK2 inhibitors.. Many drugs are now under investigations targeting different pathways critical for MPN development, such as the JAK-STAT (JAK2 inhibitors: INCB018424 or ruxolitinib, TG101348 or SAR302503, CYT387, SB1518, CEP701 and LY2784544) and the PI3K/AKT/mTOR (everolimus) pathways, or act through remodeling of chromatin with a key role in epigenetics (givinostat, panobinostat and vorinostat). The most relevant effects were spleen size reduction and relief of constitutional symptoms.. Patients who might benefit from JAK2 inhibitors in clinical practice are mostly those with splenomegaly or with constitutional symptoms. We should alert patients with lower hemoglobin levels that these therapies might, although temporarily, favor the need for red blood cell transfusions.

Topics: Animals; Benzamides; Clinical Trials as Topic; Disease Models, Animal; Drug Evaluation, Preclinical; Humans; Janus Kinase 2; Janus Kinases; Mice; Myeloproliferative Disorders; Nitriles; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidines; Sulfonamides

Myelofibrosis (myelofibrosis) is a deadly blood neoplasia with the worst prognosis among myeloproliferative neoplasms (MPN). The JAK2 inhibitors ruxolitinib and fedratinib have been approved for treatment of myelofibrosis, but they do not offer significant improvement of bone marrow fibrosis. CDK6 expression is significantly elevated in MPN/myelofibrosis hematopoietic progenitor cells. In this study, we investigated the efficacy of CDK4/6 inhibitor palbociclib alone or in combination with ruxolitinib in Jak2V617F and MPLW515L murine models of myelofibrosis. Treatment with palbociclib alone significantly reduced leukocytosis and splenomegaly and inhibited bone marrow fibrosis in Jak2V617F and MPLW515L mouse models of myelofibrosis. Combined treatment of palbociclib and ruxolitinib resulted in normalization of peripheral blood leukocyte counts, marked reduction of spleen size, and abrogation of bone marrow fibrosis in murine models of myelofibrosis. Palbociclib treatment also preferentially inhibited Jak2V617F mutant hematopoietic progenitors in mice. Mechanistically, treatment with palbociclib or depletion of CDK6 inhibited Aurora kinase, NF-κB, and TGFβ signaling pathways in Jak2V617F mutant hematopoietic cells and attenuated expression of fibrotic markers in the bone marrow. Overall, these data suggest that palbociclib in combination with ruxolitinib may have therapeutic potential for treatment of myelofibrosis and support the clinical investigation of this drug combination in patients with myelofibrosis. SIGNIFICANCE: These findings demonstrate that CDK6 inhibitor palbociclib in combination with ruxolitinib ameliorates myelofibrosis, suggesting this drug combination could be an effective therapeutic strategy against this devastating blood disorder.

Topics: Animals; Base Sequence; Bone Marrow; Bone Marrow Cells; Cell Line, Tumor; Cyclin-Dependent Kinase 6; Disease Models, Animal; Fibrosis; Gene Expression Profiling; Hematopoiesis; Hematopoietic Stem Cells; Humans; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Nitriles; Piperazines; Primary Myelofibrosis; Pyrazoles; Pyridines; Pyrimidines; Pyrrolidines; Stem Cells; Sulfonamides

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Hepatic fibrosis, characterized by an excessive extracellular matrix (ECM) accumulation, leading to scar-tissue formation is a growing health problem worldwide. Hepatocellular damage due to liver injury triggers inflammation and transdifferentiation of quiescent hepatic stellate cells (HSCs) into proliferative, contractile, and ECM-producing myofibroblasts. Involvement of the Janus kinase (JAK)-2 pathway in the pathogenesis of fibrosis has been reported earlier. However, in this study, we have investigated the effect of selective JAK2 antagonist TG101348 in fibroblasts and inflammatory macrophages and

Topics: 3T3 Cells; Animals; Carbon Tetrachloride; Cell Line, Tumor; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Hep G2 Cells; Humans; Liver; Liver Cirrhosis; Macrophages; Male; Mice; Mice, Inbred C57BL; Myofibroblasts; Nitrogen Oxides; Pyrrolidines; Signal Transduction; Sulfonamides; Transforming Growth Factor beta

Recent clinical trials suggest that patients with myelofibrosis can develop Wernicke's encephalopathy (WE) when treated with fedratinib, a specific Janus kinase-2 (JAK-2) inhibitor. To investigate this issue, we have examined (1) if fedratinib can produce or alter the course of this disorder, (2) its effects on thiamine-dependent enzyme activity and thiamine status, and (3) its influence on the uptake of thiamine. Animals administered fedratinib for 28days at a comparable dose used to treat human cases of myelofibrosis showed no evidence of clinical signs of thiamine deficiency (TD). Rats treated with a combination of fedratinib and TD exhibited no neurological differences in their progress to the symptomatic stage when compared to thiamine-deficient animals only. Treatment with the JAK-2 inhibitor did not compromise erythrocyte transketolase activity, and thiamine status was not affected in a major way unlike animals with TD. In addition, treatment of cultured astrocytes with fedratinib did not diminish the uptake of thiamine into these cells. Our findings suggest that treatment with fedratinib does not lead to or alter the progress of TD, and do not support the notion that administration of this JAK-2 inhibitor directly results in the development of WE due to inhibition of thiamine transport. Known adverse effects of fedratinib involving compromised gastrointestinal function may be an important indirect contributing factor to previously reported cases of WE in patients with myelofibrosis.

Topics: Animals; Disease Models, Animal; Janus Kinase 2; Male; Pyrrolidines; Rats; Rats, Sprague-Dawley; Sulfonamides; Thiamine; Thiamine Deficiency; Wernicke Encephalopathy

CALR mutations are identified in about 30% of JAK2/MPL-unmutated myeloproliferative neoplasms (MPNs) including essential thrombocythemia (ET) and primary myelofibrosis. Although the molecular pathogenesis of CALR mutations leading to MPNs has been studied using in vitro cell lines models, how mutant CALR may affect developmental hematopoiesis remains unknown. Here we took advantage of the zebrafish model to examine the effects of mutant CALR on early hematopoiesis and model human CALR-mutated MPNs. We identified three zebrafish genes orthologous to human CALR, referred to as calr, calr3a and calr3b. The expression of CALR-del52 and CALR-ins5 mutants caused an increase in the hematopoietic stem/progenitor cells followed by thrombocytosis without affecting normal angiogenesis. The expression of CALR mutants also perturbed early developmental hematopoiesis in zebrafish. Importantly, morpholino knockdown of mpl but not epor or csf3r could significantly attenuate the effects of mutant CALR. Furthermore, the expression of mutant CALR caused jak-stat signaling activation in zebrafish that could be blocked by JAK inhibitors (ruxolitinib and fedratinib). These findings showed that mutant CALR activates jak-stat signaling through an mpl-dependent mechanism to mediate pathogenic thrombopoiesis in zebrafish, and illustrated that the signaling machinery related to mutant CALR tumorigenesis are conserved between human and zebrafish.

Topics: Animals; Calreticulin; Carcinogenesis; Disease Models, Animal; Gene Expression Regulation, Neoplastic; Hematopoiesis; Hematopoietic Stem Cells; Humans; Janus Kinase 2; Mutation; Myeloproliferative Disorders; Nitriles; Primary Myelofibrosis; Pyrazoles; Pyrimidines; Pyrrolidines; Receptors, Thrombopoietin; Signal Transduction; Sulfonamides; Thrombocythemia, Essential; Thrombocytosis; Zebrafish

We have recently reported that interferon gamma receptor deficient (IFNγR-/-) allogeneic donor T cells result in significantly less graft-versus-host disease (GvHD) than wild-type (WT) T cells, while maintaining an anti-leukemia or graft-versus-leukemia (GvL) effect after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We demonstrated that IFNγR signaling regulates alloreactive T cell trafficking to GvHD target organs through expression of the chemokine receptor CXCR3 in alloreactive T cells. Since IFNγR signaling is mediated via JAK1/JAK2, we tested the effect of JAK1/JAK2 inhibition on GvHD. While we demonstrated that pharmacologic blockade of JAK1/JAK2 in WT T cells using the JAK1/JAK2 inhibitor, INCB018424 (Ruxolitinib), resulted in a similar effect to IFNγR-/- T cells both in vitro (reduction of CXCR3 expression in T cells) and in vivo (mitigation of GvHD after allo-HSCT), it remains to be determined if in vivo administration of INCB018424 will result in preservation of GvL while reducing GvHD. Here, we report that INCB018424 reduces GvHD and preserves the beneficial GvL effect in two different murine MHC-mismatched allo-HSCT models and using two different murine leukemia models (lymphoid leukemia and myeloid leukemia). In addition, prolonged administration of INCB018424 further improves survival after allo-HSCT and is superior to other JAK1/JAK2 inhibitors, such as TG101348 or AZD1480. These data suggest that pharmacologic inhibition of JAK1/JAK2 might be a promising therapeutic approach to achieve the beneficial anti-leukemia effect and overcome HLA-barriers in allo-HSCT. It might also be exploited in other diseases besides GvHD, such as organ transplant rejection, chronic inflammatory diseases and autoimmune diseases.

Topics: Animals; Disease Models, Animal; Gene Expression Regulation, Leukemic; Graft vs Host Disease; Graft vs Leukemia Effect; Hematopoietic Stem Cell Transplantation; Interferon gamma Receptor; Janus Kinase 1; Janus Kinase 2; Leukemia, Lymphoid; Leukemia, Myeloid; Mice; Mice, Inbred BALB C; Mice, Knockout; Nitriles; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Pyrrolidines; Receptors, Interferon; Signal Transduction; Sulfonamides; T-Lymphocytes; Transplantation, Homologous; Whole-Body Irradiation

We report a Jak2V617F knockin mouse myeloproliferative neoplasm (MPN) model resembling human polycythemia vera (PV). The MPN is serially transplantable and we demonstrate that the hematopoietic stem cell (HSC) compartment has the unique capacity for disease initiation but does not have a significant selective competitive advantage over wild-type HSCs. In contrast, myeloid progenitor populations are expanded and skewed toward the erythroid lineage, but cannot transplant the disease. Treatment with a JAK2 kinase inhibitor ameliorated the MPN phenotype, but did not eliminate the disease-initiating population. These findings provide insights into the consequences of JAK2 activation on HSC differentiation and function and have the potential to inform therapeutic approaches to JAK2V617F-positive MPN.

Topics: Amino Acid Substitution; Animals; Antigens, CD; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; Cell Count; Cell Differentiation; Disease Models, Animal; Erythroid Precursor Cells; Erythropoietin; Gene Expression; Gene Expression Profiling; Hematocrit; Hematopoietic Stem Cell Transplantation; Hematopoietic Stem Cells; Heterozygote; Humans; Janus Kinase 2; Megakaryocyte Progenitor Cells; Megakaryocyte-Erythroid Progenitor Cells; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myeloid Progenitor Cells; Myeloproliferative Disorders; Polycythemia Vera; Protein Kinase Inhibitors; Pyrrolidines; Spleen; Sulfonamides; Survival Analysis

We report that TG101348, a selective small-molecule inhibitor of JAK2 with an in vitro IC50 of approximately 3 nM, shows therapeutic efficacy in a murine model of myeloproliferative disease induced by the JAK2V617F mutation. In treated animals, there was a statistically significant reduction in hematocrit and leukocyte count, a dose-dependent reduction/elimination of extramedullary hematopoiesis, and, at least in some instances, evidence for attenuation of myelofibrosis. There were no apparent toxicities and no effect on T cell number. In vivo responses were correlated with surrogate endpoints, including reduction/elimination of JAK2V617F disease burden assessed by quantitative genomic PCR, suppression of endogenous erythroid colony formation, and in vivo inhibition of JAK-STAT signal transduction as assessed by flow cytometric measurement of phosphorylated Stat5.

Topics: Amino Acid Substitution; Animals; Bone Marrow Transplantation; Cell Line, Tumor; Colony-Forming Units Assay; Disease Models, Animal; Endpoint Determination; Flow Cytometry; Hematopoietic System; Humans; Janus Kinase 2; Mice; Mice, Inbred C57BL; Phenylalanine; Polycythemia Vera; Protein Kinase Inhibitors; Pyrrolidines; Signal Transduction; Sulfonamides; Survival Rate; Treatment Outcome; Valine