RESUMO
BACKGROUND: It has been described in mice models that myeloproliferative neoplasm (MPN) with JAK2-V617F mutation has an increased expression of programmed death-ligand 1 (PD-L1) in megakaryocytes leading to cancer immune evasion by inhibiting the T-lymphocytes. AIMS: To quantify and compare the PD-L1 expression on bone marrow (BM) of patients with MPN JAK2 positive, negative, and normal controls. METHODS: We collected BM of patients with MPN JAK2 positive, negative and normal controls from 1990 to 2019. We also created a scoring system to quantify PD-L1 expression in megakaryocytes. RESULTS: We obtained 14 BM with JAK2 positive PMF, 5 JAK2 negative PMF, and 10 patients with normal BM biopsies. PD-L1 expression was higher in the JAK2 positive group compared with the control group with a score of 212.6 versus 121.1 (t-value 2.05, p-value 0.025). In addition, the score was higher in the PMF group regardless of JAK2 mutational status when compared with the control group with score of 205.9 versus 121.1 (t-value 2.12, p-value 0.021). There was no difference in the PD-L1 score between the JAK2 negative versus the control group 187.2 versus 121.1 (t-value 1.02, p-value 0.162). CONCLUSION: These findings suggest that PMF patients with a JAK2 mutation have a higher PD-L1 expression in megakaryocytes compared with the control group. We postulate that the combination of checkpoint and JAK2 inhibitors may be an active treatment option in JAK2 mutated PMF given the higher PD-L1 expression.
Assuntos
Antígeno B7-H1 , Janus Quinase 2 , Mielofibrose Primária , Humanos , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Janus Quinase 2/genética , Janus Quinase 2/metabolismo , Mielofibrose Primária/genética , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologia , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Adulto , Mutação , Medula Óssea/patologia , Megacariócitos/patologia , Megacariócitos/metabolismo , Idoso de 80 Anos ou mais , Estudos de Casos e ControlesRESUMO
Myelofibrosis is a chronic myeloproliferative disorder characterized by bone marrow fibrosis, splenomegaly, anemia, and constitutional symptoms, with a median survival of ≈6 years from diagnosis. While currently approved Janus kinase (JAK) inhibitors (ruxolitinib, fedratinib) improve splenomegaly and symptoms, most can exacerbate myelofibrosis-related anemia, a negative prognostic factor for survival. Momelotinib is a novel JAK1/JAK2/activin A receptor type 1 (ACVR1) inhibitor approved in the US, European Union, and the UK and is the first JAK inhibitor indicated specifically for patients with myelofibrosis with anemia. Momelotinib not only addresses the splenomegaly and symptoms associated with myelofibrosis by suppressing the hyperactive JAK-STAT (signal transducer and activator of transcription) pathway but also improves anemia and reduces transfusion dependency through ACVR1 inhibition. The recommended dose of momelotinib is 200 mg orally once daily, which was established after review of safety, efficacy, pharmacokinetic, and pharmacodynamic data. Momelotinib is metabolized primarily by CYP3A4 and excreted as metabolites in feces and urine. Steady-state maximum concentration is 479 ng/mL (CV%, 61%), with a mean AUCtau of 3288 ng.h/mL (CV%, 60%); its major metabolite, M21, is active (≈40% of pharmacological activity of parent), with a metabolite-to-parent AUC ratio of 1.4-2.1. This review describes momelotinib's mechanism of action, detailing how the JAK-STAT pathway is involved in myelofibrosis pathogenesis and ACVR1 inhibition decreases hepcidin, leading to improved erythropoiesis. Additionally, it summarizes the pivotal studies and data that informed the recommended dosage and risk/benefit assessment.
Assuntos
Pesquisa Translacional Biomédica , Humanos , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Benzamidas/farmacologia , Benzamidas/farmacocinética , Benzamidas/efeitos adversos , Pirimidinas/farmacocinética , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Pirimidinas/administração & dosagem , Pirimidinas/efeitos adversos , Animais , Janus Quinase 1/antagonistas & inibidores , Janus Quinase 1/metabolismo , Transdução de Sinais/efeitos dos fármacos , Janus Quinase 2/antagonistas & inibidores , Janus Quinase 2/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/farmacocinética , Inibidores de Proteínas Quinases/uso terapêutico , Inibidores de Proteínas Quinases/administração & dosagem , Hidrocarbonetos Aromáticos com PontesRESUMO
Despite increased understanding of the genomic landscape of Myeloproliferative Neoplasms (MPNs), the pathological mechanisms underlying abnormal megakaryocyte (Mk)-stromal crosstalk and fibrotic progression in MPNs remain unclear. We conducted mass spectrometry-based proteomics on mice with Romiplostim-dependent myelofibrosis to reveal alterations in signaling pathways and protein changes in Mks, platelets, and bone marrow (BM) cells. The chemokine Platelet Factor 4 (PF4)/Cxcl4 was up-regulated in all proteomes and increased in plasma and BM fluids of fibrotic mice. High TPO concentrations sustained in vitro PF4 synthesis and secretion in cultured Mks, while Ruxolitinib restrains the abnormal PF4 expression in vivo. We discovered that PF4 is rapidly internalized by stromal cells through surface glycosaminoglycans (GAGs) to promote myofibroblast differentiation. Cxcl4 gene silencing in Mks mitigated the profibrotic phenotype of stromal cells in TPO-saturated co-culture conditions. Consistently, extensive stromal PF4 uptake and altered GAGs deposition were detected in Romiplostim-treated, JAK2V617F mice and BM biopsies of MPN patients. BM PF4 levels and Mk/platelet CXCL4 expression were elevated in patients, exclusively in overt fibrosis. Finally, pharmacological inhibition of GAGs ameliorated in vivo fibrosis in Romiplostim-treated mice. Thus, our findings highlight the critical role of PF4 in the fibrosis progression of MPNs and substantiate the potential therapeutic strategy of neutralizing PF4-GAGs interaction.
Assuntos
Fator Plaquetário 4 , Mielofibrose Primária , Proteômica , Fator Plaquetário 4/metabolismo , Fator Plaquetário 4/genética , Animais , Camundongos , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologia , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/genética , Humanos , Proteômica/métodos , Megacariócitos/metabolismo , Megacariócitos/patologia , Camundongos Endogâmicos C57BL , Diferenciação CelularRESUMO
Studies conducted on animal models have identified several therapeutic targets for myelofibrosis, the most severe of the myeloproliferative neoplasms. Unfortunately, many of the drugs which were effective in pre-clinical settings had modest efficacy when tested in the clinic. This discrepancy suggests that treatment for this disease requires combination therapies. To rationalize possible combinations, the efficacy in the Gata1low model of drugs currently used for these patients (the JAK1/2 inhibitor Ruxolitinib) was compared with that of drugs targeting other abnormalities, such as p27kip1 (Aplidin), TGF-ß (SB431542, inhibiting ALK5 downstream to transforming growth factor beta (TGF-ß) signaling and TGF-ß trap AVID200), P-selectin (RB40.34), and CXCL1 (Reparixin, inhibiting the CXCL1 receptors CXCR1/2). The comparison was carried out by expressing the endpoints, which had either already been published or had been retrospectively obtained for this study, as the fold change of the values in the corresponding vehicles. In this model, only Ruxolitinib was found to decrease spleen size, only Aplidin and SB431542/AVID200 increased platelet counts, and with the exception of AVID200, all the inhibitors reduced fibrosis and microvessel density. The greatest effects were exerted by Reparixin, which also reduced TGF-ß content. None of the drugs reduced osteopetrosis. These results suggest that future therapies for myelofibrosis should consider combining JAK1/2 inhibitors with drugs targeting hematopoietic stem cells (p27Kip1) or the pro-inflammatory milieu (TGF-ß or CXCL1).
Assuntos
Janus Quinase 1 , Selectina-P , Mielofibrose Primária , Pirimidinas , Receptores de Interleucina-8B , Fator de Crescimento Transformador beta , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologia , Fator de Crescimento Transformador beta/metabolismo , Animais , Janus Quinase 1/antagonistas & inibidores , Janus Quinase 1/metabolismo , Selectina-P/metabolismo , Receptores de Interleucina-8B/antagonistas & inibidores , Receptores de Interleucina-8B/metabolismo , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Receptores de Interleucina-8A/antagonistas & inibidores , Receptores de Interleucina-8A/metabolismo , Camundongos , Janus Quinase 2/metabolismo , Janus Quinase 2/antagonistas & inibidores , Nitrilas/uso terapêutico , Nitrilas/farmacologia , Modelos Animais de Doenças , Quimioterapia Combinada , Fator de Transcrição GATA1/metabolismo , Fator de Transcrição GATA1/genética , Pirazóis/farmacologia , Pirazóis/uso terapêutico , HumanosRESUMO
Myeloproliferative neoplasms (MPNs), namely, polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are clonal stem cell disorders defined by an excessive production of functionally mature and terminally differentiated myeloid cells. MPNs can transform into secondary acute myeloid leukemia (sAML/blast phase MPN) and are linked to alterations in the redox balance, i.e., elevated concentrations of reactive oxygen species and markers of oxidative stress (OS), and changes in antioxidant systems. We evaluated OS in 117 chronic phase MPNs and 21 sAML cases versus controls by measuring total antioxidant capacity (TAC) and 8-hydroxy-2'-deoxy-guanosine (8-OHdG) concentrations. TAC was higher in MPNs than controls (p = 0.03), particularly in ET (p = 0.04) and PMF (p = 0.01). MPL W515L-positive MPNs had higher TAC than controls (p = 0.002) and triple-negative MPNs (p = 0.01). PMF patients who had treatment expressed lower TAC than therapy-free subjects (p = 0.03). 8-OHdG concentrations were similar between controls and MPNs, controls and sAML, and MPNs and sAML. We noted associations between TAC and MPNs (OR = 1.82; p = 0.05), i.e., ET (OR = 2.36; p = 0.03) and PMF (OR = 2.11; p = 0.03), but not sAML. 8-OHdG concentrations were not associated with MPNs (OR = 1.73; p = 0.62) or sAML (OR = 1.89; p = 0.49). In conclusion, we detected redox imbalances in MPNs based on disease subtype, driver mutations, and treatment history.
Assuntos
8-Hidroxi-2'-Desoxiguanosina , Antioxidantes , Transtornos Mieloproliferativos , Humanos , Masculino , Feminino , 8-Hidroxi-2'-Desoxiguanosina/metabolismo , Pessoa de Meia-Idade , Idoso , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/metabolismo , Transtornos Mieloproliferativos/patologia , Antioxidantes/metabolismo , Adulto , Estresse Oxidativo , Idoso de 80 Anos ou mais , Crise Blástica/metabolismo , Crise Blástica/genética , Crise Blástica/patologia , Proteínas de Fusão bcr-abl/genética , Proteínas de Fusão bcr-abl/metabolismo , Mielofibrose Primária/genética , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologiaRESUMO
Dysregulated JAK/STAT hyperactivity is essential to the pathogenesis of myelofibrosis, and JAK inhibitors are the first-line treatment option for many patients. There are four FDA-approved JAK inhibitors for patients with myelofibrosis. Single-agent JAK inhibition can improve splenomegaly, symptom burden, cytopenias, and possibly survival in patients with myelofibrosis. Despite their efficacy, JAK inhibitors produce variable or short-lived responses, in part due to the large network of cooperating signaling pathways and downstream targets of JAK/STAT, which mediates upfront or acquired resistance to JAK inhibitors. Synergistic inhibition of JAK/STAT accessory pathways can increase the rates and duration of response for patients with myelofibrosis. Two recently reported, placebo-controlled phase III trials of novel agents added to JAK inhibition met their primary endpoint, and additional late-stage studies are ongoing. This paper will review role of dysregulated JAK/STAT signaling, biological plausible additional therapeutic targets and the recent advancements in combination strategies with JAK inhibitors for myelofibrosis.
Assuntos
Inibidores de Janus Quinases , Janus Quinases , Mielofibrose Primária , Transdução de Sinais , Humanos , Inibidores de Janus Quinases/uso terapêutico , Inibidores de Janus Quinases/farmacologia , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Janus Quinases/antagonistas & inibidores , Janus Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de Transcrição STAT/metabolismo , Terapia de Alvo Molecular/métodos , Resultado do Tratamento , AnimaisRESUMO
Despite advances in understanding the genetic abnormalities in myeloproliferative neoplasms (MPN) and the development of JAK2 inhibitors, there is an urgent need to devise new treatment strategies, particularly for patients with triple-negative (TN) myelofibrosis (MF) who lack mutations in the JAK2 kinase pathway and have very poor clinical outcomes. Here we report that MYC copy number gain and increased MYC expression frequently occur in TN-MF and that MYC-directed activation of S100A9, an alarmin protein that plays pivotal roles in inflammation and innate immunity, is necessary and sufficient to drive development and progression of MF. Notably, the MYC-S100A9 circuit provokes a complex network of inflammatory signaling that involves numerous hematopoietic cell types in the bone marrow microenvironment. Accordingly, genetic ablation of S100A9 or treatment with small molecules targeting the MYC-S100A9 pathway effectively ameliorates MF phenotypes, highlighting the MYC-alarmin axis as a novel therapeutic vulnerability for this subgroup of MPNs. Significance: This study establishes that MYC expression is increased in TN-MPNs via trisomy 8, that a MYC-S100A9 circuit manifest in these cases is sufficient to provoke myelofibrosis and inflammation in diverse hematopoietic cell types in the BM niche, and that the MYC-S100A9 circuit is targetable in TN-MPNs.
Assuntos
Calgranulina B , Cromossomos Humanos Par 8 , Transtornos Mieloproliferativos , Proteínas Proto-Oncogênicas c-myc , Trissomia , Cromossomos Humanos Par 8/genética , Humanos , Trissomia/genética , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Calgranulina B/genética , Calgranulina B/metabolismo , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/metabolismo , Transtornos Mieloproliferativos/patologia , Animais , Camundongos , Mielofibrose Primária/genética , Mielofibrose Primária/patologia , Mielofibrose Primária/metabolismo , Transdução de Sinais/genéticaRESUMO
INTRODUCTION: Myelofibrosis (MF) is a hematologic disease characterized by bone marrow fibrosis, cytopenias, splenomegaly, and constitutional symptoms. Recent years have seen the emergence of novel therapeutic agents, notably ruxolitinib and fedratinib, which target the Janus kinases (JAK) pathway. However, their myelosuppressive effect coupled with the persistence, and even worsening anemia remains a significant challenge, leading usually to treatment discontinuation. AREAS COVERED: This review focuses on Momelotinib (MMB), a unique JAK inhibitor that has shown promise in MF treatment, particularly in improving anemia. MMB inhibits type 1 kinase activin A receptor or activin receptor-like kinase-2 (ACVR1/ALK2), with consequent rebalancing of the SMAD pathways and reduced transcription of hepcidin. Moreover, it seems that MMB could reduce the serum levels of several inflammatory cytokines responsible for anemia. Clinical trials have demonstrated MMB's efficacy in reducing spleen size, alleviating symptoms, and improving anemia, with a favorable safety profile compared to other JAK inhibitors, both in treatment-naïve and in pre-treated patients. EXPERT OPINION: Due to its mechanism of action, MMB represents a valuable therapeutic option in MF, addressing the clinical challenge of anemia and potentially improving outcomes for patients with hematologic malignancies. Ongoing research explores MMB's potential in acute myeloid leukemia and combination therapies.
Assuntos
Mielofibrose Primária , Pirimidinas , Humanos , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Pirimidinas/uso terapêutico , Pirimidinas/farmacologia , Animais , Benzamidas/uso terapêutico , Benzamidas/farmacologia , Inibidores de Janus Quinases/uso terapêutico , Inibidores de Janus Quinases/farmacologia , Anemia/tratamento farmacológico , Hidrocarbonetos Aromáticos com PontesRESUMO
The classical BCR::ABL1-negative myeloproliferative neoplasms (MPN) form a group of bone marrow (BM) diseases with the potential to progress to acute myeloid leukemia or develop marrow fibrosis and subsequent BM failure. The mechanism by which BM fibrosis develops and the factors that drive stromal activation and fibrosis are not well understood. Cellular Communication Network 2 (CCN2), also known as CTGF (Connective Tissue Growth Factor), is a profibrotic matricellular protein functioning as an important driver and biomarker of fibrosis in a wide range of diseases outside the marrow. CCN2 can promote fibrosis directly or by acting as a factor downstream of TGF-ß, the latter already known to contribute to myelofibrosis in MPN.To study the possible involvement of CCN2 in BM fibrosis in MPN, we assessed CCN2 protein expression by immunohistochemistry in 75 BM biopsies (55 × MPN and 20 × normal controls). We found variable expression of CCN2 in megakaryocytes with significant overexpression in a subgroup of 7 (13%) MPN cases; 4 of them (3 × essential thrombocytemia and 1 × prefibrotic primary myelofibrosis) showed no fibrosis (MF-0), 2 (1 × post-polycythemic myelofibrosis and 1 × primary myelofibrosis) showed moderate fibrosis (MF-2), and 1 (primary myelofibrosis) severe fibrosis (MF-3). Remarkably, CCN2 expression did not correlate with fibrosis or other disease parameters such as platelet count or thrombovascular events, neither in this subgroup nor in the whole study group. This suggests that in BM of MPN patients other, CCN2-independent pathways (such as noncanonical TGF-ß signaling) may be more important for the development of fibrosis.
Assuntos
Fator de Crescimento do Tecido Conjuntivo , Transtornos Mieloproliferativos , Mielofibrose Primária , Transdução de Sinais , Fator de Crescimento Transformador beta , Humanos , Fator de Crescimento do Tecido Conjuntivo/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Mielofibrose Primária/patologia , Mielofibrose Primária/metabolismo , Pessoa de Meia-Idade , Masculino , Feminino , Idoso , Transtornos Mieloproliferativos/patologia , Transtornos Mieloproliferativos/metabolismo , Adulto , Medula Óssea/patologia , Medula Óssea/metabolismo , Idoso de 80 Anos ou mais , Imuno-Histoquímica , Fibrose/patologiaRESUMO
BCR::ABL1 negative myeloproliferative neoplasms (MPN) form a distinct group of hematologic malignancies characterized by sustained proliferation of cells from multiple myeloid lineages. With a median survival of 16-35 months in patients with high-risk disease, primary myelofibrosis (PMF) is considered the most aggressive entity amongst all BCR::ABL1 MPN. Additionally, for a significant subset of patients, MPN evolve into secondary acute myeloid leukemia (AML), which has an even poorer prognosis compared to de novo AML. As the exact mechanisms of disease development and progression remain to be elucidated, current therapeutic approaches fail to prevent disease progression or transformation into secondary AML. As each MPN entity is characterized by sustained activation of various immune cells and raised cytokine concentrations within bone marrow (BM) and peripheral blood (PB), MPN may be considered to be typical inflammation-related malignancies. However, the exact role and consequences of increased cytokine concentrations within BM and PB plasma has still not been completely established. Up-regulated cytokines can stimulate cellular proliferation, or contribute to the development of an inflammation-related BM niche resulting in genotoxicity and thereby supporting mutagenesis. The neutrophil chemoattractant CXCL8 is of specific interest as its concentration is increased within PB and BM plasma of patients with PMF. Increased concentration of CXCL8 negatively correlates with overall survival. Furthermore, blockage of the CXCR1/2 axis appears to be able to reduce BM fibrosis and megakaryocyte dysmorphia in murine models. In this review, we summarize available evidence on the role of the CXCL8-CXCR1/2 axis within the pathogenesis of PMF, and discuss potential therapeutic modalities targeting either CXCL8 or its cognate receptors CXCR1/2.
Assuntos
Interleucina-8 , Mielofibrose Primária , Receptores de Interleucina-8A , Receptores de Interleucina-8B , Animais , Humanos , Interleucina-8/metabolismo , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologia , Mielofibrose Primária/genética , Mielofibrose Primária/diagnóstico , Mielofibrose Primária/etiologia , Mielofibrose Primária/mortalidade , Receptores de Interleucina-8A/metabolismo , Receptores de Interleucina-8A/genética , Receptores de Interleucina-8B/metabolismo , Receptores de Interleucina-8B/genética , Transdução de SinaisRESUMO
BACKGROUND: Myelofibrosis is the most aggressive subtype among classical BCR::ABL1 negative myeloproliferative neoplasms. About 90% of cases are driven by constitutive activation of 1 of 3 genes impacting the JAK/STAT pathway: JAK2, CALR, and MPL. Triple-negative myelofibrosis (TN-MF) accounts for only 5%-10% of cases and carries the worst outcomes. Little has been described about this subset of disease. Given the marked heterogeneity surrounding disease biology, clonal architecture, clinical presentation, and poor outcomes in TN-MF, identification of features of interest and assessment of treatment response are areas in need of further investigation. PATIENTS AND METHODS: We collected and evaluated baseline clinical and molecular parameters from 626 patients with a diagnosis of myelofibrosis who presented to the H. Lee Moffitt Cancer Center in Tampa (Florida, US) between 2003 and 2021 and compared them based on presence or absence of the three classical phenotypic driver mutations. RESULTS: A small proportion of patients (6%) harbored TN-MF which correlated with inferior outcomes, marked by a 4-year reduction in overall survival time compared to the non-TN cohort (mOS 37.4 months vs. 85.7 months; P = .009) and higher rates of leukemic transformation. More pronounced thrombocytopenia and anemia, lower LDH, EPO levels, as well as lower percentage of marrow blasts at baseline were more commonly seen in TN-MF (P < .05). Similarly, patients with TN-MF had higher risk disease per DIPSS+ and GIPSS. Mutations impacting RNA splicing, epigenetic modification and signaling, specifically SRSF2, SETBP1, IDH2, CBL, and GNAS, were more commonly seen among those lacking a classical phenotypic driver. The prevalence of co-mutant ASXL1/SRSF2 clones was significantly higher in TN-MF as was trisomy 8. TN patients had fewer responses (46.2% vs. 63.4%) and shorter duration of response to ruxolitinib. CONCLUSION: TN-MF is invariably associated with significantly decreased survival and more aggressive clinical behavior with higher rates of leukemic transformation and shorter duration of response to ruxolitinib. Mutations impacting RNA splicing, epigenetic modification and signaling (SRSF2, SETBP1, IDH2, CBL, and GNAS) are more common in TN-MF, which likely drive its aggressive course and may account for suboptimal responses to JAK inhibition.
Assuntos
Mutação , Mielofibrose Primária , Humanos , Mielofibrose Primária/genética , Mielofibrose Primária/mortalidade , Mielofibrose Primária/metabolismo , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Adulto , Resultado do Tratamento , Idoso de 80 Anos ou mais , Prognóstico , Janus Quinase 2/genética , Janus Quinase 2/metabolismoRESUMO
Bone marrow fibrosis represents an important structural change in the marrow that interferes with some of its normal functions. The aetiopathogenesis of fibrosis is not well established except in its primary form. The present review consolidates current understanding of marrow fibrosis. We searched PubMed without time restriction using key words: bone marrow and fibrosis as the main stem against the terms: growth factors, cytokines and chemokines, morphology, megakaryocytes and platelets, myeloproliferative disorders, myelodysplastic syndrome, collagen biosynthesis, mesenchymal stem cells, vitamins and minerals and hormones, and mechanism of tissue fibrosis. Tissue marrow fibrosis-related papers were short listed and analysed for the review. It emerged that bone marrow fibrosis is the outcome of complex interactions between growth factors, cytokines, chemokines and hormones together with their facilitators and inhibitors. Fibrogenesis is initiated by mobilisation of special immunophenotypic subsets of mesenchymal stem cells in the marrow that transform into fibroblasts. Fibrogenic stimuli may arise from neoplastic haemopoietic or non-hematopoietic cells, as well as immune cells involved in infections and inflammatory conditions. Autoimmunity is involved in a small subset of patients with marrow fibrosis. Megakaryocytes and platelets are either directly involved or are important intermediaries in stimulating mesenchymal stem cells. MMPs, TIMPs, TGF-ß, PDGRF, and basic FGF and CRCXL4 chemokines are involved in these processes. Genetic and epigenetic changes underlie many of these conditions.
Assuntos
Medula Óssea , Mielofibrose Primária , Humanos , Medula Óssea/metabolismo , Mielofibrose Primária/etiologia , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologia , Citocinas/metabolismo , Fibrose , Quimiocinas/metabolismo , HormôniosRESUMO
PURPOSE: Myelofibrosis (MF) is a clonal myeloproliferative neoplasm characterized by systemic symptoms, cytopenias, organomegaly, and bone marrow fibrosis. JAK2 inhibitors afford symptom and spleen burden reduction but do not alter the disease course and frequently lead to thrombocytopenia. TGFß, a pleiotropic cytokine elaborated by the MF clone, negatively regulates normal hematopoiesis, downregulates antitumor immunity, and promotes bone marrow fibrosis. Our group previously showed that AVID200, a potent and selective TGFß 1/3 trap, reduced TGFß1-induced proliferation of human mesenchymal stromal cells, phosphorylation of SMAD2, and collagen expression. Moreover, treatment of MF mononuclear cells with AVID200 led to increased numbers of progenitor cells (PC) with wild-type JAK2 rather than JAK2V617F. PATIENTS AND METHODS: We conducted an investigator-initiated, multicenter, phase Ib trial of AVID200 monotherapy in 21 patients with advanced MF. RESULTS: No dose-limiting toxicity was identified at the three dose levels tested, and grade 3/4 anemia and thrombocytopenia occurred in 28.6% and 19.0% of treated patients, respectively. After six cycles of therapy, two patients attained a clinical benefit by IWG-MRT criteria. Spleen and symptom benefits were observed across treatment cycles. Unlike other MF-directed therapies, increases in platelet counts were noted in 81% of treated patients with three patients achieving normalization. Treatment with AVID200 resulted in potent suppression of plasma TGFß1 levels and pSMAD2 in MF cells. CONCLUSIONS: AVID200 is a well-tolerated, rational, therapeutic agent for the treatment of patients with MF and should be evaluated further in patients with thrombocytopenic MF in combination with agents that target aberrant MF intracellular signaling pathways.
Assuntos
Transtornos Mieloproliferativos , Mielofibrose Primária , Trombocitopenia , Humanos , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Janus Quinase 2/metabolismo , Citocinas/uso terapêutico , Fatores Imunológicos/uso terapêutico , Trombocitopenia/induzido quimicamenteRESUMO
Myeloproliferative neoplasms (MPN) are a group of clonal haematological malignancies first described by Dameshek in 1957. The Philadelphia-negative MPN that will be described are polycythaemia vera (PV), essential thrombocythaemia (ET), pre-fibrotic myelofibrosis and primary myelofibrosis (PMF). The blood and bone marrow morphology are essential in diagnosis, for WHO classification, establishing a baseline, monitoring response to treatment and identifying changes that may indicate disease progression. The blood film changes may be in any of the cellular elements. The key bone marrow features are architecture and cellularity, relative complement of individual cell types, reticulin content and bony structure. Megakaryocytes are the most abnormal cell and key to classification, as their number, location, size and cytology are all disease-defining. Reticulin content and grade are integral to assignment of the diagnosis of myelofibrosis. Even with careful assessment of all these features, not all cases fit neatly into the diagnostic entities; there is frequent overlap reflecting the biological disease continuum rather than distinct entities. Notwithstanding this, an accurate morphologic diagnosis in MPN is crucial due to the significant differences in prognosis between different subtypes and the availability of different therapies in the era of novel agents. The distinction between "reactive" and MPN is also not always straightforward and caution needs to be exercised given the prevalence of "triple negative" MPN. Here we describe the morphology of MPN including comments on changes with disease evolution and with treatment.
Assuntos
Transtornos Mieloproliferativos , Policitemia Vera , Mielofibrose Primária , Humanos , Mielofibrose Primária/diagnóstico , Mielofibrose Primária/metabolismo , Reticulina , Transtornos Mieloproliferativos/patologia , Medula Óssea/patologia , Policitemia Vera/diagnóstico , Policitemia Vera/patologiaRESUMO
PURPOSE: Treatment options are limited beyond JAK inhibitors for patients with primary myelofibrosis (MF) or secondary MF. Preclinical studies have revealed that PI3Kδ inhibition cooperates with ruxolitinib, a JAK1/2 inhibitor, to reduce proliferation and induce apoptosis of JAK2V617F-mutant cell lines. PATIENTS AND METHODS: In a phase I dose-escalation and -expansion study, we evaluated the safety and efficacy of a selective PI3Kδ inhibitor, umbralisib, in combination with ruxolitinib in patients with MF who had a suboptimal response or lost response to ruxolitinib. Enrolled subjects were required to be on a stable dose of ruxolitinib for ≥8 weeks and continue that MTD at study enrollment. The recommended dose of umbralisib in combination with ruxolitinib was determined using a modified 3+3 dose-escalation design. Safety, pharmacokinetics, and efficacy outcomes were evaluated, and spleen size was measured with a novel automated digital atlas. RESULTS: Thirty-seven patients with MF (median age, 67 years) with prior exposure to ruxolitinib were enrolled. A total of 2 patients treated with 800 mg umbralisib experienced reversible grade 3 asymptomatic pancreatic enzyme elevation, but no dose-limiting toxicities were seen at lower umbralisib doses. Two patients (5%) achieved a durable complete response, and 12 patients (32%) met the International Working Group-Myeloproliferative Neoplasms Research and Treatment response criteria of clinical improvement. With a median follow-up of 50.3 months for censored patients, overall survival was greater than 70% after 3 years of follow-up. CONCLUSIONS: Adding umbralisib to ruxolitinib in patients was well tolerated and may resensitize patients with MF to ruxolitinib without unacceptable rates of adverse events seen with earlier generation PI3Kδ inhibitors. Randomized trials testing umbralisib in the treatment of MF should be pursued.
Assuntos
Inibidores de Janus Quinases , Mielofibrose Primária , Humanos , Idoso , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Fosfatidilinositol 3-Quinases , Pirimidinas/uso terapêutico , Nitrilas/uso terapêutico , Inibidores de Janus Quinases/uso terapêuticoRESUMO
Emperipolesis between neutrophils and megakaryocytes was first identified by transmission electron microscopy. Although rare under steady-state conditions, its frequency greatly increases in myelofibrosis, the most severe of myeloproliferative neoplasms, in which it is believed to contribute to increasing the transforming growth factor (TGF)-ß microenvironmental bioavailability responsible for fibrosis. To date, the challenge of performing studies by transmission electron microscopy has hampered the study of factors that drive the pathological emperipolesis observed in myelofibrosis. We established a user-friendly confocal microscopy method that detects emperipolesis by staining with CD42b, specifically expressed on megakaryocytes, coupled with antibodies that recognize the neutrophils (Ly6b or neutrophil elastase antibody). With such an approach, we first confirmed that the bone marrow from patients with myelofibrosis and from Gata1low mice, a model of myelofibrosis, contains great numbers of neutrophils and megakaryocytes in emperipolesis. Both in patients and Gata1low mice, the emperipolesed megakaryocytes were surrounded by high numbers of neutrophils, suggesting that neutrophil chemotaxis precedes the actual emperipolesis event. Because neutrophil chemotaxis is driven by CXCL1, the murine equivalent of human interleukin 8 that is expressed at high levels by malignant megakaryocytes, we tested the hypothesis that neutrophil/megakaryocyte emperipolesis could be reduced by reparixin, an inhibitor of CXCR1/CXCR2. Indeed, the treatment greatly reduced both neutrophil chemotaxis and their emperipolesis with the megakaryocytes in treated mice. Because treatment with reparixin was previously reported to reduce both TGF-ß content and marrow fibrosis, these results identify neutrophil/megakaryocyte emperipolesis as the cellular interaction that links interleukin 8 to TGF-ß abnormalities in the pathobiology of marrow fibrosis.
Assuntos
Emperipolese , Fator de Transcrição GATA1 , Megacariócitos , Mielofibrose Primária , Animais , Humanos , Camundongos , Emperipolese/efeitos dos fármacos , Fator de Transcrição GATA1/antagonistas & inibidores , Interleucina-8 , Megacariócitos/metabolismo , Neutrófilos/metabolismo , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
Clonal myeloproliferation and development of bone marrow (BM) fibrosis are the major pathogenetic events in myelofibrosis (MF). The identification of novel antifibrotic strategies is of utmost importance since the effectiveness of current therapies in reverting BM fibrosis is debated. We previously demonstrated that osteopontin (OPN) has a profibrotic role in MF by promoting mesenchymal stromal cells proliferation and collagen production. Moreover, increased plasma OPN correlated with higher BM fibrosis grade and inferior overall survival in MF patients. To understand whether OPN is a druggable target in MF, we assessed putative inhibitors of OPN expression in vitro and identified ERK1/2 as a major regulator of OPN production. Increased OPN plasma levels were associated with BM fibrosis development in the Romiplostim-induced MF mouse model. Moreover, ERK1/2 inhibition led to a remarkable reduction of OPN production and BM fibrosis in Romiplostim-treated mice. Strikingly, the antifibrotic effect of ERK1/2 inhibition can be mainly ascribed to the reduced OPN production since it could be recapitulated through the administration of anti-OPN neutralizing antibody. Our results demonstrate that OPN is a novel druggable target in MF and pave the way to antifibrotic therapies based on the inhibition of ERK1/2-driven OPN production or the neutralization of OPN activity.
Assuntos
Osteopontina , Mielofibrose Primária , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/metabolismo , Mielofibrose Primária/patologia , Animais , Camundongos , Modelos Animais de Doenças , Transdução de Sinais/efeitos dos fármacos , Osteopontina/antagonistas & inibidores , Osteopontina/sangue , Osteopontina/metabolismo , Fibrose/tratamento farmacológico , HumanosRESUMO
Calreticulin (CALR) mutations present the main oncogenic drivers in JAK2 wildtype (WT) myeloproliferative neoplasms (MPN), including essential thrombocythemia and myelofibrosis, where mutant (MUT) CALR is increasingly recognized as a suitable mutation-specific drug target. However, our current understanding of its mechanism-of-action is derived from mouse models or immortalized cell lines, where cross-species differences, ectopic over-expression and lack of disease penetrance are hampering translational research. Here, we describe the first human gene-engineered model of CALR MUT MPN using a CRISPR/Cas9 and adeno-associated viral vector-mediated knock-in strategy in primary human hematopoietic stem and progenitor cells (HSPCs) to establish a reproducible and trackable phenotype in vitro and in xenografted mice. Our humanized model recapitulates many disease hallmarks: thrombopoietin-independent megakaryopoiesis, myeloid-lineage skewing, splenomegaly, bone marrow fibrosis, and expansion of megakaryocyte-primed CD41+ progenitors. Strikingly, introduction of CALR mutations enforced early reprogramming of human HSPCs and the induction of an endoplasmic reticulum stress response. The observed compensatory upregulation of chaperones revealed novel mutation-specific vulnerabilities with preferential sensitivity of CALR mutant cells to inhibition of the BiP chaperone and the proteasome. Overall, our humanized model improves purely murine models and provides a readily usable basis for testing of novel therapeutic strategies in a human setting.
Assuntos
Transtornos Mieloproliferativos , Mielofibrose Primária , Humanos , Animais , Camundongos , Calreticulina/genética , Calreticulina/metabolismo , Janus Quinase 2/genética , Transtornos Mieloproliferativos/genética , Mutação , Células-Tronco Hematopoéticas/metabolismo , Mielofibrose Primária/genética , Mielofibrose Primária/metabolismoRESUMO
Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by the clonal expansion of myeloid cells, notably megakaryocytes (MKs), and an aberrant cytokine production leading to bone marrow (BM) fibrosis and insufficiency. Current treatment options are limited. TGF-ß1, a profibrotic and immunosuppressive cytokine, is involved in PMF pathogenesis. While all cell types secrete inactive, latent TGF-ß1, only a few activate the cytokine via cell type-specific mechanisms. The cellular source of the active TGF-ß1 implicated in PMF is not known. Transmembrane protein GARP binds and activates latent TGF-ß1 on the surface of regulatory T lymphocytes (Tregs) and MKs or platelets. Here, we found an increased expression of GARP in the BM and spleen of mice with PMF and tested the therapeutic potential of a monoclonal antibody (mAb) that blocks TGF-ß1 activation by GARP-expressing cells. GARP:TGF-ß1 blockade reduced not only fibrosis but also the clonal expansion of transformed cells. Using mice carrying a genetic deletion of Garp in either Tregs or MKs, we found that the therapeutic effects of GARP:TGF-ß1 blockade in PMF imply targeting GARP on Tregs. These therapeutic effects, accompanied by increased IFN-γ signals in the spleen, were lost upon CD8 T-cell depletion. Our results suggest that the selective blockade of TGF-ß1 activation by GARP-expressing Tregs increases a CD8 T-cell-mediated immune reaction that limits transformed cell expansion, providing a novel approach that could be tested to treat patients with myeloproliferative neoplasms.
Assuntos
Mielofibrose Primária , Fator de Crescimento Transformador beta1 , Camundongos , Animais , Mielofibrose Primária/tratamento farmacológico , Mielofibrose Primária/genética , Mielofibrose Primária/metabolismo , Anticorpos Monoclonais/farmacologia , Anticorpos Monoclonais/uso terapêutico , Anticorpos Monoclonais/metabolismo , Citocinas/metabolismo , Fibrose , Linfócitos T ReguladoresRESUMO
Myelofibrosis is a myeloproliferative neoplasm characterized by splenomegaly, debilitating constitutional symptoms and bone marrow failure. Disease-related anemia is common and associated with an inferior quality of life and survival. Unfortunately, few therapies exist to improve hemoglobin in myelofibrosis patients. Momelotinib is a JAK1/JAK2 inhibitor that also antagonizes ACVR1, leading to downregulation of hepcidin expression and increased availability of iron for erythropoiesis. In clinical testing, momelotinib has demonstrated a unique ability to improve hemoglobin and reduce transfusion burden in myelofibrosis patients with baseline anemia, while producing reductions in spleen size and symptom burden. This review explores the preclinical rationale, clinical trial data and future role of momelotinib in the evolving therapeutic landscape of myelofibrosis.
Patients with myelofibrosis (MF), a blood cancer, experience many symptoms including tiredness, night sweats and an increased spleen size. They also may experience low red blood cell counts (anemia) and require blood transfusions. MF is normally treated with medications called JAK inhibitors, but they worsen anemia. Momelotinib is a new JAK inhibitor that may be able to improve anemia. This is a review article that covers the available information on momelotinib and describes how this new drug may be incorporated into the future treatment of MF.