JAK2, CALR, MPL and triple-negative mutational status has a direct impact on symptom severity and disease burden assessed by MPN10 score in myeloproliferative neoplasms (MPNs). Among 93 patients; median MPN10 score was 48 (5-76) in JAK2 mutants versus 25 (4-80) in JAK2 negative (p < .001); 22.5 (4-65) in CALR mutants versus 35 (5-80) in CALR negative (p < .050) and 21 (10-48) in triple negative versus 40 (4-80) in JAK2/CALR/MPL mutants (p < .001). At three years, progression free and overall survival of JAK2-positive versus JAK2-negative patients were 62% versus 100% (p < .001); 85% versus 100% (p = .011) and were 100% versus 78% (p = .067); 100% versus 92% (p = .197) in CALR-positive versus CALR-negative patients and 100% versus 75% (p = .004); 100% versus 90% (p = .015) in triple negative versus mutant patients, respectively. MPN10 score in association with driver gene mutations can be used as a predictor of survival in MPN patients.

Aims: JAK2V617F(JAK2), calreticulin(CALR), and MPL515L/K(MPL) mutations are important in essential thrombocythemia(ET) and may be associated with various clinical consequences of the disease. Thisstudy aimed to compare the clinical and haematological parameters of ET patients regarding the mentioned mutations and the role of plateletcrit(PCT).

Methods: Seventy patients who were diagnosed with ET between 2005 and 2017 in a single centre were included in this descriptive study. The initial symptoms and clinical findings were retrieved from the electronic database. JAK2 gene V617F mutations, MPL gene exon 10 mutations, and CALR gene exon 9 DNA sequence analyses were performed. Forty-one healthy volunteers were included to perform ROC curve analysis for interpreting PCT value.

Results: The distributions of patients according to the mutations were as follows: Thirty-seven(52.9%) patients were JAK2-positive, 15(21.4%) were CALR-positive, 2(2.8%) patients were positive for both CALR and JAK2, and 1 (1.4%) was only MPL-positive. Fifteen (21.4%) patients were triple-negative. The ET patients with JAK2 mutation showed a higher level of haemoglobin at the time of diagnosis. The ET patients with CALR mutation presented with higher platelet and LDH levels (p=0.002 and p=0.001, respectively). The PCT level was higher in the CALR-positive group when compared to the others (p=0.026). A sensitivity value of 97.6 % and specificity value of 98.6% were determined regarding PCT% at a cut-off value of 0.37 inET patients. In CALR-positive patients, the sensitivity and specificity values were 100% for the PCT at a cut-off value of 0.42%.

Conclusion: We determined that the platelet count and blood LDH level was high in the ET patient group with CALR mutation. Besides,we found that the blood haemoglobin level was higher in the ET patient group with JAK2 mutation. Additionally, the PCT levelwashigher in the CALR groupwhen compared to theotherpatientgroups.

Keywords: JAK2V617F; CALR,MPL515L/K; Essential thrombocythemia; platelet count; plateletcrit.

Hematopoiesis is a highly regulated and complex process involving hematopoietic stem cells (HSCs), cell surface adhesion molecules, and cytokines as well as cells of the hematopoietic niche in the bone marrow (BM). Myeloproliferative neoplasms (MPNs) are characterized by clonal expansion of HSCs involving one or more blood cell lineages. Philadelphia-negative MPNs (Ph-neg MPNs) comprise polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). In nearly all patients with Ph-neg MPN, mutations in the genes encoding janus kinase 2 (JAK2), calreticulin (CALR), or the thrombopoietin receptor (MPL) can be detected and, together with additional mutations in epigenetic modifier genes, these genetic aberrations contribute to the clonal expansion of the cells. In addition to these intracellular changes in the malignant clone, inflammatory processes involving both the clonal and the non-clonal cells contribute to the signs and symptoms of the patients, as well as to progression of the disease to myelofibrosis (MF) or acute leukemia, and to thrombotic complications. This contribution has been corroborated in preclinical studies including mouse models and patient-derived iPS cells, and in clinical trials, using anti-inflammatory drugs such as JAK inhibitors and steroids, or immunomodulatory drugs such as IMiDs and interferon-alpha (IFNa), all of which change the (im)balance of circulating inflammatory factors (e.g., TNFa, IL-1b, and TGFβ) in MPN. Currently, allogeneic hematopoietic (stem) cell transplantation (allo-HCT) remains the only curative treatment for Ph-neg MPN and is the treatment of choice in intermediate-2 and high-risk MF. HCT can reverse inflammatory changes induced by MPN as well as fibrosis in a large proportion of patients, but it also induces itself profound changes in inflammatory cells and cytokines in the patient, which may help to eradicate the disease but also in part cause significant morbidity (e.g., by graft-versus-host disease). In this review, we focus on the contribution of aberrant inflammation to disease pathogenesis in Ph-neg MPN as well as the current understanding of its alterations after allogeneic HCT.

Keywords: JAK inhibitors; allogeneic hematopoietic stem cell transplantation; cytokines; inflammation; myeloproliferative neoplasm.

OBJECTIVE

The primary objective was to determine the prevalence of calreticulin (CALR) mutation in patients with non-JAK2V617F mutated essential thrombocythemia (ET). The secondary objectives were to evaluate the accuracy of CALR mutation analysis by high-resolution melting (HRM) analysis and real-time polymerase chain reaction (PCR) compared with DNA sequencing and to compare clinical characteristics of CALR mutated and JAK2V617F mutated ET.

METHODS

This was a prospective cohort study involving ET patients registered at Chiang Mai University in the period September 2015-September 2017 who were aged more than 2 years, and did not harbor JAK2V617F mutation. The presence of CALR mutation was established by DNA sequencing, HRM, and real-time PCR for type 1 and type 2 mutation. Clinical data were compared with that from ET patients with mutated JAK2V617F.

RESULTS

Twenty-eight patients were enrolled onto the study. CALR mutations were found in 10 patients (35.7%). Three patients had type 1 mutation, 5 patients had type 2 mutation, 1 patient had type 18 mutation, and 1 patients had novel mutations (c.1093 C-G, c.1098_1131 del, c.1135 G-A). HRM could differentiate between the types of mutation in complete agreement with DNA sequencing. Patients with a CALR mutation showed a significantly greater male predominance and had a higher platelet count when compared with 42 JAK2V617F patients.

CONCLUSIONS

The prevalence of CALR mutation in JAK2V617F-negative ET in this study is 35.7%. HRM is an effective method of detecting CALR mutation and is a more advantageous method of screening for CALR mutation.

BACKGROUND

Hematopoietic malignancies are a group of blood cell disorders characterized by abnormal hematopoietic proliferation.

OBJECTIVE

The identification of specific clinicopathologic characteristics and tumor-related gene status provides critical information on potential therapeutic targets.

METHODS

The specimens were tested with immunohistochemistry, flow cytometry, RT-PCR and fragment analysis.

RESULTS

In this study, a patient with a long history of tobacco use was reported with a diagnosis of simultaneous low-grade B-cell lymphoproliferative disorder (LPD) and myeloproliferative neoplasm (MPN). Mutational analysis revealed that JAK2 V617F mutation and CALR mutation with 52bp deletion were present in this patient.

CONCLUSIONS

These results suggest that lymphoproliferative and myeloproliferative neoplasms may coexist, although the pathogenetic mechanism of coexisting hematologic requires further investigation. Additionally, the data indicate that JAK2 V617F and CALR mutations are not mutually exclusive and the actual frequency of simultaneous JAK2 V617F and CALR mutations is unknown. Whether the coexistence of these mutations imposes any biological or clinical significance awaits further investigation.

The understanding of the basic molecular mechanisms of myeloproliferative neoplasms in the last few years led to updating of their diagnostic criteria in the recent classification of myeloid and lymphoid neoplasms by the WHO, which was published in 2017. The major changes relating to the diagnosis of myeloproliferative neoplasms include lowering of the hemoglobin threshold and mandatory bone marrow biopsy as major criteria for the diagnosis of polycythemia vera, as well as adding acquired mutation in either CALR or MPL in addition to the common JAK2V617F mutation as a major criterion for diagnosing essential thrombocythemia or myelofibrosis. We review the newest discoveries on the pathogenesis of myeloproliferative neoplasms, highlighting the relevant new additions to their diagnostic criteria, and relevant therapeutic considerations.

The therapeutic landscape of the Philadelphia-negative myeloproliferative neoplasms (MPNs) is markedly changing consequent to the development of JAK-inhibitors and the use of ruxolitinib (RUX) in patients with myelofibrosis (MF) and patients with polycythemia vera (PV) who develop refractoriness or intolerance to hydroxyurea. The use of Interferon-alpha2 (IFN) is rapidly expanding in several countries, based upon favourable safety and efficacy profiles in several single-arm studies during the last 30 years, displaying complete hematological remissions in a large proportion of patients, a reduction in the JAK2V617 F and CALR mutational burden and in a subset of patients with PV with normalisation of the bone marrow after long-term treatment - even being sustained for several years after discontinuation of IFN. To this end the concept of chronic inflammation as the driving force for MPN disease progression is being increasingly recognized. This novel concept has initiated phase II studies in patients with PV and MF of combination therapy with IFN and RUX. Areas covered and Expert commentary: Herein we highlight the background, the rationales and perspectives for this novel combinatorial approach which is foreseen as the most encouraging and promising treatment for patients with MPNs - hopefully with the potential of cure - at least operational cure - in a subset of patients.

In myeloproliferative neoplasms (MPN), JAK2V617F allele burden measurement has an impact on prognosis that helps in patient monitoring. Less is known about its usefulness in CALR-mutated cases. Additional mutations found by next-generation sequencing have also shown an impact on prognosis that may drive therapeutic choices, especially in myelofibrosis, but few studies focused on CALR-mutated patients. We performed a molecular evaluation combining next-generation sequencing with a myeloid panel and CALR allele burden measurement at diagnosis and during follow-up in a cohort of 45 patients with CALR-mutated essential thrombocythaemia. The bone marrow histology was also blindly reviewed in order to apply the WHO2016 classification. The most frequently mutated gene was TET2 (11/21 mutations). CALR type 1-like patients appear to have a more complex molecular landscape. We found an association between disease progression and CALR allele burden increase during follow-up, independently of additional mutations and WHO2016-reviewed diagnosis. Patients with disease progression at the time of follow-up showed a significant increase in CALR allele burden (+16·7%, P = 0·005) whereas patients without disease progression had a stable allele burden (+3·7%, P = 0·194). This result argues for clinical interest in CALR allele burden monitoring.

Activation of the JAK-STAT pathway by driver mutations of JAK2, CALR or MPL is the pathogenesis of myeloproliferative neoplasms (MPN). Mutations in epigenetic regulators that often coexist with driver mutations reinforce the function of MPN initiating cells and support MPN onset and maintenance. In myelofibrosis patients, JAK2 inhibitors exerted an innovative therapeutic effect on splenomegaly and constitutional symptoms, but had minimal effects on the JAK2V617F allele burden. Epigenetic abnormalities may be a good target for novel therapeutic strategies aiming to induce molecular remission in myelofibrosis patients. New information obtained by next-generation sequencing technologies would greatly contribute to elucidation of the mechanisms underlying MPN onset, progression and leukemic transformation.

Individualized medicine is important for patients with myeloproliferative neoplasms (MPNs), including essential thrombocythemia, polycythemia vera, and myelofibrosis, which are heterogeneous in terms of genetic mutation profile, prognosis, disease burden, and symptoms. Status of MPN driver mutations in JAK2, CALR, and MPL (or lack of one of these mutations) and other myeloid mutations (ASXL1, SRSF2, CBL, and IDH1/2, among others) affects diagnosis and prognosis. Management begins with estimating the prognosis, disease burden including MPN symptoms, and prevention of vascular events. Allogeneic stem cell transplantation is the definitive therapy in a subset of patients with myelofibrosis, the majority of whom receive JAK inhibition with ruxolitinib to relieve splenomegaly and symptoms and to prolong survival. Ruxolitinib is now a second-line therapy in polycythemia vera, with pegylated interferon being evaluated as a potential front-line therapy compared with hydroxyurea. The therapeutic landscape is evolving to include new JAK inhibitors, which may affect cytopenias (pacritinib and momelotinib), combination therapies including ruxolitinib, and novel targets such as pentraxin and telomerase. Assessing the therapeutic efficacy (including symptom impact) and toxicity of these new approaches is necessary to determine longitudinal management of MPNs in clinical practice and is a key component of "individualizing" care for patients with MPNs.

The introduction of next-generation sequencing has broadened the genetic landscape of myeloproliferative neoplasms (MPNs) beyond JAK2, MPL, and CALR. However, the biological role and clinical impact of most other mutations are not well defined. We interrogated 101 genes in 143 BCR-ABL1-negative MPNs in chronic phase from 2 large institutions. We detected SF3B1 mutations in 15 cases (10%) and set to investigate the clinical, morphologic, and molecular features of SF3B1 mutated (SF3B1+) MPNs in comparison to SF3B1 wild-type (SF3B1-) cases and to identify distinctive features with myelodysplastic/myeloproliferative neoplasms with ring sideroblasts (RS) and thrombocytosis, which can show partial clinical and morphological overlap with MPNs. SF3B1+ cases were enriched in primary myelofibrosis in both prefibrotic and fibrotic stage, but mutations of SF3B1 seem to occur only as a late event in the fibrotic phase of essential thrombocythemia and polycythemia vera. SF3B1+ MPNs showed borderline lower hemoglobin but no other clinical or molecular differences compared to SF3B1- MPNs. Of note, RS were present only in a subset of SF3B1+ cases (4/10) without any other feature of erythroid or granulocytic dysplasia. Our results suggest that mutations in SF3B1 are not a rare event in MPNs, especially in primary myelofibrosis and during late fibrotic stages of essential thrombocythemia and polycythemia vera, but are not associated with myelodysplastic progression. Careful examination of bone marrow and peripheral blood for morphologic dysplasia is crucial to reach the correct diagnosis and avoid a misdiagnosis of myelodysplastic/myeloproliferative neoplasms with RS and thrombocytosis, a pitfall with potential prognostic and therapeutic implications.

In late 2013, somatic mutations in calreticulin (CALR), mainly those involving insertions and deletions in exon 9, attracted the great attention of hematologists and researchers. These JAK2- and MPL- mutual exclusive mutations enjoy a favorable specificity and prevalence (20-30%) in patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF), suggesting promise for these mutations in disease management. Moreover, these genetic variations are now also considered as a group of independent risk factors for disease prognosis. In this mini-review, we will document the value of CALR mutations in disease diagnosis, prognosis, and therapeutic strategy selection, and we will discuss current advances in methods to detect these mutations.

Because of its capacity to increase a physiologic inflammatory response, to stimulate phagocytosis, to promote cell lysis and to enhance pathogen immunogenicity, the complement system is a crucial component of both the innate and adaptive immune responses. However, many infectious agents resist the activation of this system by expressing or secreting proteins with a role as complement regulatory, mainly inhibitory, proteins. Trypanosoma cruzi, the causal agent of Chagas disease, a reemerging microbial ailment, possesses several virulence factors with capacity to inhibit complement at different stages of activation. T. cruzi calreticulin (TcCalr) is a highly-conserved, endoplasmic reticulum-resident chaperone that the parasite translocates to the extracellular environment, where it exerts a variety of functions. Among these functions, TcCalr binds C1, MBL and ficolins, thus inhibiting the classical and lectin pathways of complement at their earliest stages of activation. Moreover, the TcCalr/C1 interaction also mediates infectivity by mimicking a strategy used by apoptotic cells for their removal. More recently, it has been determined that these Calr strategies are also used by a variety of other parasites. In addition, as reviewed elsewhere, TcCalr inhibits angiogenesis, promotes wound healing and reduces tumor growth. Complement C1 is also involved in some of these properties. Knowledge on the role of virulence factors, such as TcCalr, and their interactions with complement components in host-parasite interactions, may lead toward the description of new anti-parasite therapies and prophylaxis.

Keywords: C1q; Trypanosoma cruzi; calreticulin; complement; host immune evasion; host-parasite interaction.

Primary Myelofibrosis is a BCR-ABL negative myeloproliferative neoplasm with a variety of hematologicalpresentations, including thrombosis, bleeding diathesis and marrow fibrosis. It is estimated to have an incidence of1.5 per 100,000 people each year. Although JAK2 or MPL mutations are seen in PMF, several other mutations haverecently been documented, including mutations in CALR, epigenetic regulators like TET, ASXL1, and 13q deletions.The identification of these mutations has improved the ability to develop novel treatment options. These include JAKinhibitors like ruxolitinib, heat shock protein-90 inhibitors like ganetespib, histone deacetylase inhibitors includingpanobinostat, pracinostat, vorinostat and givinostat, hypomethylating agents like decitabine, hedgehog inhibitors likeglasdegib, PI3K, AKT and mTOR inhibitors like everolimus as well as telomerase inhibitors like imtelstat. Researchon novel therapeutic options is being actively pursued in order to expand treatment options for primary myelofibrosishowever currently, there is no curative therapy other than allogenic hematopoietic stem cell transplantation (ASCT)which is possible in select patients.

Childhood essential thrombocythemia (ET) is a rare chronic myeloproliferative disorder. The quality of life of ET patients may decrease as a result of ischemic and hemorrhagic complications of unclear origin. Our goal was to characterize the hemostatic system in children with ET. We genotyped and investigated blood samples from 20 children with ET in a prospective case series study using platelet aggregation, functional flow cytometry (FC) assay and standard clotting assays. Three children had a JAK2V617F mutation, 4 had mutations in CALR and 13 were triple-negative. Myelofibrosis in stage 1-2 was detected in 3 children. Three patients had bleeding episodes and seven had ischemic events. Aggregation in response to collagen, adenosine diphosphate, and ristomycin was decreased in all patients. In FC, significant changes in the whole patient group compared to the healthy children control group were decrease in the resting forward scatter and PAC1 binding (activated GPIIb/IIIa) level. For the activated platelets, dense granules release (by mepacrine), PAC1, and GPIIb/IIIa levels were significantly decreased. GPIb/V/IX, P-selectin, and phosphatidylserine levels manifested only moderate differences. Forward and side scatter changes in response to stimulation (representing shape change) and dense granules release were significantly lower in the 3 patients with bleeding than in the 17 patients without hemorrhage. Activated partial thromboplastin time was slightly prolonged, prothrombin index was slightly shortened and thrombin time was normal, while fibrinogen was mildly decreased in the ET patients. It could be concluded that the observed platelet function defects could be related to bleeding in ET, and be potentially used as a marker.

Myeloproliferative neoplasms (MPNs) are characterized by activation of the JAK-STAT pathway due to driver mutations including JAK2V617F and MPLW515K/L, as well as to mutations in CALR. Driver mutations phosphorylate multiple STAT proteins that lead to proliferations, differentiations and cytokine secretions of various hematopoietic cells. However, hematopoietic cells carrying JAK2V617F, which causes excessive cellular proliferation and differentiation, do not necessarily have a clonal growth advantage in terms of hematopoietic repopulation. Alterations of epigenetic modifiers involving histone modifications and DNA methylations, which often co-exist with driver mutations and eventually upregulate several oncogenes, may play crucial roles in long-term clinical courses characterized by progression to myelofibrosis or acute leukemia in MPNs. In addition to JAK2 inhibition, molecules altered by abnormal epigenetic modifications may be worth exploring as potential new therapeutic targets in MPNs.

Calreticulin (CALR) and JAK2-V617F gene mutations, which are major genetic mutations in patients with primary myelofibrosis (PMF) and essential thrombocythemia (ET), exert different effects on the clinical features and outcomes of these diseases. We analyzed 88 and 9 patients with ET and PMF, respectively, and determined the differences in the clinical characteristics of ET patients with JAK2-V617F compared with CALR mutations. The frequency of the JAK2-V617F and CALR mutations were 64 and 22 %, respectively. Patients with CALR mutations were younger, had a lower white blood cell count, and had a lower rate of thrombotic events than patients with the JAK2 mutation. The neutrophil alkaline phosphatase (NAP) score of 16 patients with CALR mutations was significantly lower than the normal controls, which was mainly due to the high proportion of NAP-negative neutrophils. This is the first report to show an association between CALR mutations in patients with myeloproliferative neoplasms (MPN) and the NAP score. Although the mechanism is unclear, the NAP score could be a useful and reliable biochemical marker to discriminate the mutational status of MPN patients. Further investigation is warranted to determine whether these characteristics contribute to the pathogenesis of MPN and the NAP score.

Motility is important for virulence, biofilm formation, and the environmental adaptation of many bacteria. Vibrio parahaemolyticus (V. parahaemolyticus) contains two flagellar systems that are responsible for motility, and are tightly regulated by transcription regulators and sigma factors. In this study, we identified a novel transcription factor, VPA1701, which regulates the swarming motility of V. parahaemolyticus. The VPA1701 deletion mutant (ΔVPA1701) eliminated the swarming motility on the surface of BHI agar plates and reduced colonization in infant rabbits. RNA-seq assays, confirmed by qRT-PCR, indicated that VPA1701 regulated the expression of lateral flagellar cluster genes. Further analyses revealed that VPA1701 directly binds to the promoter region of the flgBCDEFGHIJKL cluster to regulate the expression of lateral flagellar genes. CalR was originally identified as a repressor for the swarming motility of V. parahaemolyticus, and it was inhibited by calcium. In this study, we found that VPA1701 could inhibit the expression of the calR gene to increase the swarming motility of V. parahaemolyticus. Calcium downregulated the expression of calR, indicating that calcium could increase swarming motility of ΔVPA1701 by inhibiting calR. Thus, this study illustrates how the transcription factor VPA1701 regulates the expression of lateral flagellar genes and calR to control the swarming motility of V. parahaemolyticus.

Objective: To analyze the genetic mutations and clinical features of the subtypes of classical BCR-ABL-negative myeloproliferative neoplasm (MPN) . Methods: Mutations of 108 newly diagnosed BCR-ABL-negative MPN patients [including 55 patients with essential thrombocytopenia (ET) , 24 with polycythemia vera (PV) , and 29 with primary myelofibrosis (PMF) ] were identified using next-generation sequencing with 127-gene panel, and the relationship between gene mutations and clinical features were analyzed. Results: Total 211 mutations in 32 genes were detected in 100 MPN patients (92.59% ) , per capita carried (1.96±1.32) mutations. 85.19% (92/108) patients carried the driver gene (JAK2, CALR, MPL) mutations, 69.56% (64/92) of these patients carried at least 1 additional gene mutation. In descending order of mutation frequency, the highest frequency was for activation signaling pathway genes (42.2% , 89/211) , methylation genes (17.6% , 36/211) , and chromatin-modified genes (16.1% , 34/211) . There was a significant difference in the number of mutations in the activation signaling pathway genes, epigenetic regulatory genes, spliceosomes, and RNA metabolism genes among the three MPN subgroups. The average number of additional mutations in PMF patients was higher than that in ET and PV patients (1.69±1.39, 0.67±0.70, 0.87±1.22, χ(2)=13.445, P=0.001) . MPN-SAF-TSS (MPN 10 score) (P=0.006) and myelofibrosis level (P=0.015) in patients with ≥ 3 mutant genes were higher and the HGB level (P=0.002) was lower than in those with<3 mutations. Twenty-six patients (24.1% ) carried high-risk mutation (HMR) , and patients with HMR had lower PLT (P=0.017) , HGB levels (P<0.001) , and higher myelofibrosis level (P=0.010) and MPN10 score (P<0.001) . The frequency of ASXL1 mutations was higher in PMF than in PV patients (34.5% vs. 4.2% , P=0.005) . PMF patients with ASXL1 had lower levels of PLT and HGB (P=0.029 and 0.019) . Conclusion: 69.56% of MPN patients carry at least one additional mutation, and 24.1% patients had HMR. Each subgroup had different mutation patterns. PMF patients had a higher average number of additional gene mutations, especially a higher frequency of ASXL1 mutation; PLT and HGB levels were lower in ASXL1 mutation PMF patients.

目的： 分析经典型BCR-ABL阴性骨髓增殖性肿瘤（MPN）的基因突变及临床特征。 方法： 应用二代测序方法检测108例初诊BCR-ABL阴性MPN患者[原发性血小板增多症（ET）55例，真性红细胞增多症（PV）24例，原发性骨髓纤维化（PMF）29例]与疾病相关的127个基因突变情况，并分析基因突变与临床特征间的关系。 结果： 108例MPN患者中，100例（92.59％）检出32种基因共211个突变，人均检出（1.96±1.32）个突变。85.19％（92/108）的患者检出驱动基因（JAK2、CALR、MPL）突变，其中69.56％（64/92）的患者至少检出1种附加基因突变。按突变频率由高到低依次为激活信号通路基因（42.2％，89/211）、DNA甲基化基因（17.6％，36/211）、染色质修饰基因（16.1％，34/211）。PV、ET、PMF三组间激活信号通路基因、表观遗传调节基因、剪接体和RNA代谢基因突变个数差异均有统计学意义，PMF附加基因平均突变数目高于ET及PV患者（1.69±1.39、0.67±0.70、0.87±1.22，χ(2)＝13.445，P＝0.001）。检出≥3个突变基因患者MPN总症状评估量表（MPN 10评分）（P＝0.006）、骨髓纤维化程度（P＝0.015）均较检出<3个突变基因患者高，且HGB水平更低（P＝0.002）；26例（24.1％）患者检出高危基因突变（HMR），HMR突变的患者具有更低的PLT（P＝0.017）和HGB水平（P<0.001），更高的骨髓纤维化程度（P＝0.010）、MPN10评分（P<0.001）。PMF患者ASXL1突变频率高于PV患者（37.9％对4.2％，P＝0.005），ASXL1突变的PMF患者具有更低的PLT和HGB水平（P＝0.029、0.019）。 结论： 近七成MPN患者检出至少1种附加基因突变，24.1％检出HMR突变，各亚组有不同的基因突变模式；PMF患者附加基因平均突变数目更多，ASXL1突变频率更高。ASXL1突变的PMF患者PLT和HGB水平更低。.

Keywords: ASXL1; Driver gene; JAK2; Myeloproliferative neoplasm; Next-generation sequencing.

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.

Myeloproliferative neoplasms (MPN), are clonal hematopoietic stem cell (HSC) disorders driven by gain-of-function mutations in JAK2 (JAK2-V617F), CALR or MPL genes. MPN treatment options currently mainly consist of cytoreductive therapy with hydroxyurea and JAK2 inhibitors such as ruxolitinib and fedratinib. Pegylated interferon-alpha can induce complete molecular remission (CMR) in some MPN patients when applied at early stages of disease. The ultimate goal of modern MPN treatment is to develop novel therapies that specifically target mutant HSCs in MPN and consistently induce CMR. Basic research has identified a growing number of candidate drugs with promising effects in vitro. A first step on the way to developing these compounds into drugs approved for treatment of MPN patients often consists of examining the effects in vivo using pre-clinical mouse models of MPN. Here we review the current state of MPN mouse models and the experimental setup for their optimal use in drug testing. In addition to novel compounds, combinatorial therapeutic approaches are often considered for the treatment of MPN. Optimized and validated mouse models can provide an efficient way to rapidly assess and select the most promising combinations and thereby contribute to accelerating the development of novel therapies of MPN.