Mutation-Driven S100A8 Overexpression Confers Aberrant Phenotypes in Type 1 CALR-Mutated MPN.

Numerous pathogenic CALR exon 9 mutations have been identified in myeloproliferative neoplasms (MPN), with type 1 (52bp deletion; CALRDEL) and type 2 (5bp insertion; CALRINS) being the most prevalent. Despite the universal pathobiology of MPN driven by various CALR mutants, it is unclear why different CALR mutations result in diverse clinical phenotypes. Through RNA sequencing followed by validation at the protein and mRNA levels, we found that S100A8 was specifically enriched in CALRDEL but not in CALRINS MPN-model cells. The expression of S100a8 could be regulated by STAT3 based on luciferase reporter assay complemented with inhibitor treatment. Pyrosequencing demonstrated relative hypomethylation in two CpG sites within the potential pSTAT3-targeting S100a8 promoter region in CALRDEL cells as compared to CALRINS cells, suggesting that distinct epigenetic alteration could factor into the divergent S100A8 levels in these cells. The functional analysis confirmed that S100A8 non-redundantly contributed to accelerated cellular proliferation and reduced apoptosis in CALRDEL cells. Clinical validation showed significantly enhanced S100A8 expression in CALRDEL-mutated MPN patients compared to CALRINS-mutated cases, and thrombocytosis was less prominent in those with S100A8 upregulation. This study provides indispensable insights into how different CALR mutations discrepantly drive the expression of specific genes that contributes to unique phenotypes in MPN.

Comparison of antiplatelet antibody profiles between hepatitis C virus-associated immune thrombocytopenia and primary immune thrombocytopenia.

Hepatitis C virus-associated immune thrombocytopenia (HCV-ITP) has been assumed to be one of secondary ITP and associated with antiplatelet antibodies. This study was to clarify the antibody profile in HCV-ITP compared with primary ITP. We enrolled 55 HCV-ITP, 30 primary ITP, 11 Helicobacter pylori-ITP, 21 HCV control, and 16 healthy volunteers. We reviewed their blood cell counts, autoimmune markers, and spleen size. We used enzyme-linked immunosorbent assay kit to detect the specific antibody to glycoproteins IIb/IIIa, Ia/IIa, Ib/IX, IV, and human leukocyte antigen (HLA) class I. Compared with primary ITP patients, HCV-ITP patients had an older age, lower white blood cell (WBC) count and fewer presented with severe thrombocytopenia. The rate of positive antibody detection was 63.6% for the HCV-ITP group higher than the rate of 40% for the primary ITP. In the HCV control, antiplatelet antibodies were detected in 38.1% patients and no one had more than two types of antibodies. The antiplatelet antibodies correlated to severer thrombocytopenia. An HLA class I antibody was associated with lower WBCs and larger spleen. In conclusion, HCV-ITP patients had a high rate of positive antiplatelet antibody. The antibodies were associated with not only lower platelets but also leukopenia and splenomegaly.

Real-world experience with Ropeginterferon-alpha 2b (Besremi) in Philadelphia-negative myeloproliferative neoplasms.

BACKGROUND/PURPOSE: Ropeginterferon alpha-2b (Ropeg) is a novel pegylated interferon-alpha recently approved for the treatment of polycythemia vera (PV) in Europe. However, other than data from clinical trials, little is known about this agent in real world practice. METHODS: A compassionate use program employing Ropeg for treating patients with unmet medical need was initiated in Taiwan in 2017. Herein, we collected clinical data and assessed the safety as well as efficacy of Ropeg in nine patients treated in this program. RESULTS: Collectively, among evaluable patients, both the molecular response and complete blood count remission rates were 62.5%. Most therapy-related side effects were mild, and there was no treatment discontinuation attributable to intolerable adverse events. The agent also showed efficacy in symptom amelioration and spleen size reduction. Although no specific patterns of cytokine level alteration could be identified, significantly attenuated plasma levels of inflammation markers were observed in one particular patient who happened to have normalized spleen size and most remarkable reduction in JAK2 mutant allele burden, indicating all-around improvement in every aspect of this case. Furthermore, plasma hepcidin levels increased in two-thirds of PV patients, illustrating the potential of Ropeg to restore normal regulation of erythropoiesis. Using RNA sequencing on pre- and post-treatment samples from one patient, we demonstrated altered expression of genes participating in IFN response, inflammation, apoptosis, and cellular differentiation. CONCLUSION: Conclusively, observed signs of efficacy and safety in our real-world experience prove Ropeg as a promising option for the treatment of MPN.

Molecular heterogeneity unravelled by single-cell transcriptomics in patients with essential thrombocythaemia.

Significant phenotypic heterogeneity exists in patients with all subtypes of myeloproliferative neoplasms (MPN), including essential thrombocythaemia (ET). Single-cell RNA sequencing (scRNA-Seq) holds the promise of unravelling the biology of MPN at an unprecedented level of resolution. Herein we employed this approach to dissect the transcriptomes in the CD34+ cells from the peripheral blood of seven previously untreated ET patients and one healthy adult. The mutational profiles in these patients were as follows: JAK2 V617F in two, CALR in three (one type I and two type II) and triple-negative (TN) in two. Our results reveal substantial heterogeneity within this enrolled cohort of patients. Activation of JAK/STAT signalling was recognized in discrepant progenitor lineages among different samples. Significantly disparate molecular profiling was identified in the comparison between ET patients and the control, between patients with different driver mutations (JAK2 V617F and CALR exon 9 indel), and even between patients harbouring the same driver. Intra-individual clonal diversity was also found in the CD34+ progenitor population of a patient, possibly indicating the presence of multiple clones in this case. Estimation of subpopulation size based on cellular immunophenotyping suggested differentiation bias in all analysed samples. Furthermore, combining the transcriptomic information with data from targeted sequencing enabled us to unravel key somatic mutations that are molecularly relevant. To conclude, we demonstrated that scRNA-Seq extended our knowledge of clonal diversity and inter-individual heterogeneity in patients with ET. The obtained information could potentially leapfrog our efforts in the elucidation of the pathogenesis of the disease.

Aberrant let7a/HMGA2 signaling activity with unique clinical phenotype in JAK2-mutated myeloproliferative neoplasms.

High mobility group AT-hook 2 (HMGA2) is an architectural transcription factor that is negatively regulated by let-7 microRNA through binding to it's 3'-untranslated region. Transgenic mice expressing Hmga2 with a truncation of its 3'-untranslated region has been shown to exhibit a myeloproliferative phenotype. To decipher the let-7-HMGA2 axis in myeloproliferative neoplasms, we employed an in vitro model supplemented with clinical correlation. Ba/F3 cells with inducible JAK2V617F expression (Ton.JAK2.V617F cells) showed upregulation of HMGA2 with concurrent let-7a repression. Ton.JAK2.V617F cells treated with a let-7a inhibitor exhibited further escalation of Hmga2 expression, while a let-7a mimic diminished the Hmga2 transcript level. Hmga2 overexpression conferred JAK2-mutated cells with a survival advantage through inhibited apoptosis. A pan-JAK inhibitor, INC424, increased the expression of let-7a, downregulated the level of Hmga2, and led to increased apoptosis in Ton.JAK2.V617F cells in a dose-dependent manner. In samples from 151 patients with myeloproliferative neoplasms, there was a modest inverse correlation between the expression levels of let-7a and HMGA2 Overexpression of HMGA2 was detected in 29 (19.2%) of the cases, and it was more commonly seen in patients with essential thrombocythemia than in those with polycythemia vera (26.9% vs 12.7%, P=0.044). Patients with upregulated HMGA2 showed an increased propensity for developing major thrombotic events, and they were more likely to harbor one of the 3 driver myeloproliferative neoplasm mutations in JAK2, MPL and CALR Our findings suggest that, in a subset of myeloproliferative neoplasm patients, the let-7-HMGA2 axis plays a prominent role in the pathogenesis of the disease that leads to unique clinical phenotypes.

The Genomic Landscape in Philadelphia-Negative Myeloproliferative Neoplasm Patients with Second Cancers.

Patients with myeloproliferative neoplasms (MPNs) are characterized by systemic inflammation. With the indolent nature of the diseases, second cancers (SCs) have emerged as a challenging issue in afflicted patients. Epidemiological studies have confirmed the excessive risk of SCs in MPNs, but little is known about their molecular basis. To explore further, we used whole exome sequencing to explore the genetic changes in the granulocytes of 26 paired MPN patients with or without SC. We noticed that MPN−SC patients harbor genomic variants of distinct genes, among which a unique pattern of co-occurrence or mutual exclusiveness could be identified. We also found that mutated genes in MPN−SC samples were enriched in immune-related pathways and inflammatory networks, an observation further supported by their increased plasma levels of TGF-ß and IL-23. Noteworthily, variants of KRT6A, a gene capable of mediating tumor-associate macrophage activity, were more commonly detected in MPN−SC patients. Analysis through OncodriveCLUST disclosed that KRT6A replaces JAK2V617F as the more prominent disease driver in MPN−SC, whereas a major mutation in this gene (KRT6A c.745T>C) in our patients is linked to human carcinoma and predicted to be pathogenic in COSMIC database. Overall, we demonstrate that inflammation could be indispensable in MPN−SC pathogenesis.

Clinicopathological characteristics and treatment outcome in obese patients with diffuse large B-cell lymphoma.

BACKGROUND: Aberrant MYC and BCL2 expression, cell of origin (COO), and National Comprehensive Cancer Network international prognostic index (NCCN-IPI) are commonly used for risk assessment and treatment decision in patients with diffuse large B-cell lymphoma (DLBCL). Although obesity has been shown to be of predictive value in DLBCL patients, it remains unclear whether it retains its prognostic relevance after those aforementioned novel factors being taken into consideration. METHODS: Patients with DLBCL were identified retrospectively in a single institute and data were collected through electronic databases and pharmacy records. RESULTS: Fifteen (17.6%) out of the 85 patients with DLBCL in our cohort were categorized as obese. They had lower platelet counts, were younger and more likely to harbor either BCL2- or MYC-overexpressing tumors. The NCCN-IPI scores, COO, and other clinical parameters were not significantly different between obese and non-obese patients. In spite that obesity adversely affected the treatment response to immunochemotherapy, multivariate analysis showed that only NCCN-IPI risk categories [hazard ratio (HR) 2.83 for high-intermediate or high-risk, versus low-intermediate or low-risk, P=0.034] and BCL2/MYC expressional status (HR 4.12 for BCL2high and/or MYChigh, versus both low expressors, P=0.004) independently predicted progression-free survival (PFS) outcome, whereas obesity lost its prognostic value in this regard (HR 1.81 for obese patients, P=0.242). Similarly, high-intermediate to high NCCN-IPI risk (HR 3.11, P=0.034) and increased expression in either BCL2 or MYC (HR 5.63, P=0.001) both portended an inferior overall survival (OS), but the presence of obesity did not affect the outcome (HR 1.65, P=0.352). CONCLUSIONS: Our study has demonstrated that, for the first time, obesity increases the frequency of BCL2- or MYC-overexpressing tumors in patients with DLBCL.

Enhanced Risk for Specific Somatic Myeloproliferative Neoplastic Mutations in Patients with Stroke.

BACKGROUND: Somatic mutations of Janus kinase 2 (JAK2V617F), calreticulin (CALR), and myeloproliferative leukemia virus oncogene (MPL) are the major clonal molecules that drive the pathogenesis of myeloproliferative neoplasms (MPN). It is well recognized that MPN patients carry an excessive risk of thrombohemorrhagic complications. However, little is known about the prevalence of these clonal markers in patients with cerebral vascular disease. METHODS: To address this issue, 153 consecutive stroke patients in Taiwan were enrolled in the study. Allele-specific PCR (AS-PCR), real-time AS-PCR, and Illumina paired-end sequencing were employed to detect the presence of MPL, JAK2V617F, and CALR exon 9 mutations, respectively. RESULTS: JAK2V617F mutation was detectable in 13 samples (8.5%), but the allele burdens (AB) were greater than 1% in only six (3.9%) of them. Compared to JAK2-unmutated patients, those with JAK2V617F AB > 1% had significantly higher white blood count (p = 0.01), although four of the six did not exhibit MPN phenotypes. Two patients had a heterozygous CALR exon9 mutation locating outside the coding region and did not alter the amino acid sequence of this protein. On the other hand, there were no patients carrying the MPL mutations. Using patient age, baseline hemogram, and stroke-relevant risk factors, we developed a predictive model that could successfully identify stroke patients at risk of carrying clonal JAK2V617F mutation. CONCLUSION: The prevalence of JAK2V617F mutation in stroke patients was higher than that seen in general population. Based on our newly developed probability stratification model, genotyping of JAK2V617F mutation in selected patients with stroke might be warranted.