The poor outcome in high molecular risk, hydroxycarbamide-resistant/intolerant ET is not ameliorated by ruxolitinib

The role of TET2 in solid tumors and its therapeutic potential: a comprehensive review

Indeed, tumors are a significant health concern worldwide, and understanding the underlying mechanisms of tumor development is crucial for effective prevention and treatment. Epigenetics, which refers to changes in gene expression that are not caused by alterations in the DNA sequence itself, plays a critical role in the entire process of tumor development. It goes without saying that the effect of methylation on tumors is a significant aspect of epigenetics. Among the methylation modifications, DNA methylation is an important part, which plays a regulatory role in tumor-related genes. Ten-eleven translocation 2 (TET2) is a highly influential protein involved in the modification of DNA methylation. Its primary role is associated with the suppression of tumor development, making it a significant player in cancer research. However, TET2 is frequently mentioned in hematological diseases, its role in solid tumors has received little attention. Studying the changes of TET2 in solid tumors and the regulatory mechanism will facilitate its investigation as a clinical target for targeted therapy and may also provide directions for clinical treatment of malignant tumors.

Clinical impact of mutated JAK2 allele burden reduction in polycythemia vera and essential thrombocythemia

The variant allele frequency (VAF) of driver mutations (JAK2, CALR) in myeloproliferative neoplasms is associated with features of advanced disease and complications. Ruxolitinib and interferon were reported to variably reduce the mutant VAF, but the long-term impact of molecular responses (MR) remains debated. We prospectively measured changes in JAK2 and CALR VAF in 77 patients with polycythemia vera and essential thrombocythemia, treated with ruxolitinib for a median of 8 years, and assessed correlation with complete clinical and hematological response (CCHR) and outcomes. At last observation time, JAK2 VAF reduced overall from a median of 68% (range, 20%-99%) to 3.5% (0%-98%). A profound and durable MR (DMR; defined as a VAF stably ≤2%), including complete MR in 8%, was achieved in 20% of the patients, a partial MR (PMR; VAF reduction >50% of the baseline level) in 25%, and 56% had no molecular response (NMR). A CCHR was reached by 69% overall, independently of any degree of MR achieved; conversely, a DMR correlated with longer duration of CCHR and, most importantly, with reduced rate of progression to myelofibrosis and with longer myelofibrosis-free, event-free and progression-free survival. Achievement of PMR also had some favorable impact on outcomes, compared to NMR. A baseline JAK2 VAF <50%, and a VAF reduction of ≥35% after 2 years of treatment, predicted for the achievement of DMR and reduced progression to myelofibrosis. Overall, these findings support the clinical value of achieving profound, durable MR and its consideration as surrogate endpoint in future clinical trials.

Tamoxifen for the treatment of myeloproliferative neoplasms: A Phase II clinical trial and exploratory analysis

Current therapies for myeloproliferative neoplasms (MPNs) improve symptoms but have limited effect on tumor size. In preclinical studies, tamoxifen restored normal apoptosis in mutated hematopoietic stem/progenitor cells (HSPCs). TAMARIN Phase-II, multicenter, single-arm clinical trial assessed tamoxifen's safety and activity in patients with stable MPNs, no prior thrombotic events and mutated JAK2V617F, CALRins5 or CALRdel52 peripheral blood allele burden ≥20% (EudraCT 2015-005497-38). 38 patients were recruited over 112w and 32 completed 24w-treatment. The study's A'herns success criteria were met as the primary outcome ( ≥ 50% reduction in mutant allele burden at 24w) was observed in 3/38 patients. Secondary outcomes included ≥25% reduction at 24w (5/38), ≥50% reduction at 12w (0/38), thrombotic events (2/38), toxicities, hematological response, proportion of patients in each IWG-MRT response category and ELN response criteria. As exploratory outcomes, baseline analysis of HSPC transcriptome segregates responders and non-responders, suggesting a predictive signature. In responder HSPCs, longitudinal analysis shows high baseline expression of JAK-STAT signaling and oxidative phosphorylation genes, which are downregulated by tamoxifen. We further demonstrate in preclinical studies that in JAK2V617F+ cells, 4-hydroxytamoxifen inhibits mitochondrial complex-I, activates integrated stress response and decreases pathogenic JAK2-signaling. These results warrant further investigation of tamoxifen in MPN, with careful consideration of thrombotic risk.

Epigenetics in myeloproliferative neoplasms

The myeloproliferative neoplasms (MPNs) are a group of acquired clonal disorders where mutations drive proliferative disease resulting in increased blood counts and in some cases end-stage myelofibrosis. Epigenetic changes are the reversible modifications to DNA- and RNA-associated proteins that impact gene activity without changing the DNA sequence. This review summarizes mechanisms of epigenetic changes and the nucleosome. The drivers and epigenetic regulators in MPNs are outlined. In MPNs, distinct patterns of epigenetic dysregulation have been seen in chronic and in advanced phases. Methylation age and histone modification are altered in MPNs and by further treatment. The alterations found in methylation age in MPNs and with treatment are discussed, and the changes in histone modification with Janus kinase (JAK) inhibition are evaluated. Currently available therapeutic areas where the epigenome can be altered are outlined. Thus, we review the current knowledge and understanding of epigenetics in MPN and consider further management options. Understanding the epigenome and its alteration in MPNs and epigenetic changes associated with the progression of disease will lead to advances in therapeutic options.

Identification of Potential Key Genes and Regulatory Markers in Essential Thrombocythemia Through Integrated Bioinformatics Analysis and Clinical Validation

Introduction

Essential thrombocytosis (ET) is a group of myeloproliferative neoplasms characterized by abnormal proliferation of platelet and megakaryocytes. Research on potential key genes and novel regulatory markers in essential thrombocythemia (ET) is still limited.

Methods

Downloading array profiles from the Gene Expression Omnibus database, we identified the differentially expressed genes (DEGs) through comprehensive bioinformatic analysis. GO, and REACTOME pathway enrichment analysis was used to predict the potential functions of DEGs. Besides, constructing a protein–protein interaction (PPI) network through the STRING database, we validated the expression level of hub genes in an independent cohort of ET, and the transcription factors (TFs) were detected in the regulatory networks of TFs and DEGs. And the candidate drugs that are targeting hub genes were identified using the DGIdb database.

Results

We identified 63 overlap DEGs that included 21 common up-regulated and 42 common down-regulated genes from two datasets. Functional enrichment analysis shows that the DEGs are mainly enriched in the immune system and inflammatory processes. Through PPI network analysis, ACTB, PTPRC, ACTR2, FYB, STAT1, ETS1, IL7R, IKZF1, FGL2, and CTSS were selected as hub genes. Interestingly, we found that the dysregulated hub genes are also aberrantly expressed in a bone marrow cohort of ET. Moreover, we found that the expression of CTSS, FGL2, IKZF1, STAT1, FYB, ACTR2, PTPRC, and ACTB genes were significantly under-expressed in ET (P<0.05), which is consistent with our bioinformatics analysis. The ROC curve analysis also shows that these hub genes have good diagnostic value. Besides, we identified 4 TFs (SPI1, IRF4, SRF, and AR) as master transcriptional regulators that were associated with regulating the DEGs in ET. Cyclophosphamide, prednisone, fluorouracil, ruxolitinib, and lenalidomide were predicted as potential candidate drugs for the treatment of ET.

Discussion

These dysregulated genes and predicted key regulators had a significant relationship with the occurrence of ET with affecting the immune system and inflammation of the processes. Some of the immunomodulatory drugs have potential value by targeting ACTB, PTPRC, IL7R, and IKZF1 genes in the treatment of ET.

Current Concepts of Pathogenesis and Treatment of Philadelphia Chromosome-Negative Myeloproliferative Neoplasms

Philadelphia chromosome-negative myeloproliferative neoplasms are hematopoietic stem cell disorders characterized by dysregulated proliferation of mature myeloid blood cells. They can present as polycythemia vera, essential thrombocythemia, or myelofibrosis and are characterized by constitutive activation of JAK2 signaling. They share a propensity for thrombo-hemorrhagic complications and the risk of progression to acute myeloid leukemia. Attention has also been drawn to JAK2 mutant clonal hematopoiesis of indeterminate potential as a possible precursor state of MPN. Insight into the pathogenesis as well as options for the treatment of MPN has increased in the last years thanks to modern sequencing technologies and functional studies. Mutational analysis provides information on the oncogenic driver mutations in JAK2, CALR, or MPL in the majority of MPN patients. In addition, molecular markers enable more detailed prognostication and provide guidance for therapeutic decisions. While JAK2 inhibitors represent a standard of care for MF and resistant/refractory PV, allogeneic hematopoietic stem cell transplantation remains the only therapy with a curative potential in MPN so far but is reserved to a subset of patients. Thus, novel concepts for therapy are an important need, particularly in MF. Novel JAK2 inhibitors, combination therapy approaches with ruxolitinib, as well as therapeutic approaches addressing new molecular targets are in development. Current standards and recent advantages are discussed in this review.

The Prevalence of TET2 Gene Mutations in Patients with BCR-ABL-Negative Myeloproliferative Neoplasms (MPN): A Systematic Review and Meta-Analysis

Multiple recurrent somatic mutations have recently been identified in association with myeloproliferative neoplasms (MPN). This meta-analysis aims to assess the pooled prevalence of TET2 gene mutations among patients with MPN. Six databases (PubMed, Scopus, ScienceDirect, Google Scholar, Web of Science and Embase) were searched for relevant studies from inception till September 2020, without language restrictions. The eligibility criteria included BCR-ABL-negative MPN adults with TET2 gene mutations. A random-effects model was used to estimate the pooled prevalence with 95% confidence intervals (CIs). Subgroup analyses explored results among different continents and countries, WHO diagnostic criteria, screening methods and types of MF. Quality assessment was undertaken using the Joanna Briggs Institute critical appraisal tool. The study was registered with PROSPERO (CRD42020212223). Thirty-five studies were included (n = 5121, 47.1% female). Overall, the pooled prevalence of TET2 gene mutations in MPN patients was 15.5% (95% CI: 12.1-19.0%, I2 = 94%). Regional differences explained a substantial amount of heterogeneity. The prevalence of TET2 gene mutations among the three subtypes PV, ET and MF were 16.8%, 9.8% and 15.7%, respectively. The quality of the included studies was determined to be moderate-high among 83% of the included studies. Among patients with BCR-ABL-negative MPN, the overall prevalence of TET2 gene mutations was 15.5%.

Myeloproliferative neoplasms treated with hydroxyurea, pegylated interferon alpha-2A or ruxolitinib: clinicohematologic responses, quality-of-life changes and safety in the real-world setting

Introduction: Real-world data of responses, quality-of-life (QOL) changes and adverse events in patients with myeloproliferative neoplasms (MPN) on conventional therapy (hydroxyurea ± anagrelide), pegylated interferon alpha-2A (PEG-IFNα-2A) or ruxolitinib are limited. Methods: We prospectively studied MPN patients receiving conventional therapy, PEG-IFNα-2A or ruxolitinib. Next-generation sequencing of 69 myeloid-related genes was performed. Clinicohematologic responses, adverse events, and QOL (determined by the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score, MPN-SAF TSS) were evaluated. Results: Seventy men and fifty-five women with polycythemia vera (PV) (N = 23), essential thrombocythemia (ET) (N = 56) and myelofibrosis (MF) (N = 46) were studied for a median of 36 (range: 19-42) months. In PV, responses were comparable for different modalities. CREBBP mutations were associated with inferior responses. In ET, PEG-IFNα-2A resulted in superior clinicohematologic complete responses (CHCR) (P = 0.045). In MF, superior overall response rates (ORR) were associated with ruxolintib (P = 0.018) and JAK2V617F mutation (P = 0.04). For the whole cohort, ruxolitinib led to rapid and sustained reduction in spleen size within the first 6 months, and significant improvement of QOL as reflected by reduction in MPN-SAF TSS (P < 0.001). Adverse events of grades 1-2 were observed in 44%, 62% and 20% of patients receiving conventional therapy, PEG-IFNα-2A and ruxolitinib respectively; and of grade 3-4 in 7% and 9% of patients receiving PEG-IFNα-2A and ruxolitinib. Conclusions: Conventional therapy, PEG-IFNα-2A and ruxolitinib induced responses in all MPN subtypes. PEG-IFNα-2A led to superior CHCR in ET; whereas ruxolitinib resulted in superior ORR in MF, and significant reduction in spleen size and improvement in QOL.

Modification of the Histone Landscape with JAK Inhibition in Myeloproliferative Neoplasms

Dysregulation of epigenetic processes is increasingly understood to play a role in the pathogenesis of myeloproliferative neoplasms (MPNs). Ruxolitinib, a JAK/STAT inhibitor, has proved a useful addition to the therapeutic arsenal for these disorders, but has limited disease modifying activity. We determined the effect of JAK inhibition on the histone landscape of MPN cells in cell line models of MPNs and validated using samples from the MAJIC randomised clinical trial of ruxolitinib in polycythaemia vera and essential thrombocythaemia. We demonstrated an epigenetic modifying effect of ruxolitinib using a histone modification assay. The majority of 21 histone H3 modifications were upregulated, with H3K27me3 and H3K36me2 significant in the combined cell line results. Chromatin immunoprecipitation and sequencing (CHIP-seq) for three marks of interest, H3K4me1, H3K4me3 and H3K27ac, was consistent with the histone modification assay showing a significant increase in H3K4me3 and H3K27ac peaks at promoter regions, both marks of active transcription. In contrast, RNA sequencing demonstrates a coordinated reduction in gene expression in a number of cell pathways including PI3K-AKT signalling, transcriptional misregulation in cancer and JAK-STAT signalling in spite of these histone changes. This highlights the complex mechanisms of transcriptional control within the cells which was reflected in analysis of the histone landscape in patient samples following ruxolitinib treatment.

Next Generation Sequencing in MPNs. Lessons from the Past and Prospects for Use as Predictors of Prognosis and Treatment Responses

The myeloproliferative neoplasms (MPNs) are acquired hematological stem cell neoplasms characterized by driver mutations in JAK2, CALR, or MPL. Additive mutations may appear in predominantly epigenetic regulator, RNA splicing and signaling pathway genes. These molecular mutations are a hallmark of diagnostic, prognostic, and therapeutic assessment in patients with MPNs. Over the past decade, next generation sequencing (NGS) has identified multiple somatic mutations in MPNs and has contributed substantially to our understanding of the disease pathogenesis highlighting the role of clonal evolution in disease progression. In addition, disease prognostication has expanded from encompassing only clinical decision making to include genomics in prognostic scoring systems. Taking into account the decreasing costs and increasing speed and availability of high throughput technologies, the integration of NGS into a diagnostic, prognostic and therapeutic pipeline is within reach. In this review, these aspects will be discussed highlighting their role regarding disease outcome and treatment modalities in patients with MPNs.

Forging ahead or moving back: dilemmas and disappointments of novel agents for myeloproliferative neoplasms

The common 'Philadelphia chromosome'-negative myeloproliferative neoplasms (MPN) comprise essential thrombocythaemia, polycythaemia vera and myelofibrosis. These are clinically diverse disorders and present many challenges during their course, ranging from the management of very indolent, chronic-phase disease through to very aggressive stages frequently associated with poor quality of life, heavy symptom burdens and potentially life expectancies of <18 months. Their management also requires expertise in thrombosis and haemostasis in addition to marrow failure, debilitating symptom control and balancing the 'pros and cons' of intensive therapy such as allogeneic stem cell transplant versus novel and established therapies. In the past 15 years this field has seen rapid advances following an understanding of the pivotal importance of constitutive Janus kinase/signal transducers and activators of transcription (JAK/STAT) signalling, the interplay of the wider genomic landscape and the development of updated diagnostic criteria, prognostic scores and targeted therapies. In this article, we review the successes and failures of novel agents and approaches to MPN management.