Somatic mutations of JAK2 exon 12 in patients with JAK2 (V617F)-negative myeloproliferative disorders

The Role of Mutated Calreticulin in the Pathogenesis of BCR-ABL1-Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are characterized by increased proliferation of myeloid lineages in the bone marrow. Calreticulin (CALR) 52 bp deletion and CALR 5 bp insertion have been identified in essential thrombocythemia (ET) and primary myelofibrosis (PMF). There is not much data on the crosstalk between mutated CALR and MPN-related signaling pathways, such as JAK/STAT, PI3K/Akt/mTOR, and Hedgehog. Calreticulin, a multifunctional protein, takes part in many cellular processes. Nevertheless, there is little data on how mutated CALR affects the oxidative stress response and oxidative stress-induced DNA damage, apoptosis, and cell cycle progression. We aimed to investigate the role of the CALR 52 bp deletion and 5 bp insertion in the pathogenesis of MPN, including signaling pathway activation and functional analysis in CALR-mutated cells. Our data indicate that the JAK/STAT and PI3K/Akt/mTOR pathways are activated in CALR-mutated cells, and this activation does not necessarily depend on the CALR and MPL interaction. Moreover, it was found that CALR mutations impair calreticulin function, leading to reduced responses to oxidative stress and DNA damage. It was revealed that the accumulation of G2/M-CALR-mutated cells indicates that oxidative stress-induced DNA damage is difficult to repair. Taken together, this study contributes to a deeper understanding of the specific molecular mechanisms underlying CALR-mutated MPNs.

Therapeutic advances of targeting receptor tyrosine kinases in cancer

Receptor tyrosine kinases (RTKs), a category of transmembrane receptors, have gained significant clinical attention in oncology due to their central role in cancer pathogenesis. Genetic alterations, including mutations, amplifications, and overexpression of certain RTKs, are critical in creating environments conducive to tumor development. Following their discovery, extensive research has revealed how RTK dysregulation contributes to oncogenesis, with many cancer subtypes showing dependency on aberrant RTK signaling for their proliferation, survival and progression. These findings paved the way for targeted therapies that aim to inhibit crucial biological pathways in cancer. As a result, RTKs have emerged as primary targets in anticancer therapeutic development. Over the past two decades, this has led to the synthesis and clinical validation of numerous small molecule tyrosine kinase inhibitors (TKIs), now effectively utilized in treating various cancer types. In this manuscript we aim to provide a comprehensive understanding of the RTKs in the context of cancer. We explored the various alterations and overexpression of specific receptors across different malignancies, with special attention dedicated to the examination of current RTK inhibitors, highlighting their role as potential targeted therapies. By integrating the latest research findings and clinical evidence, we seek to elucidate the pivotal role of RTKs in cancer biology and the therapeutic efficacy of RTK inhibition with promising treatment outcomes.

Novel germline JAK2R715T mutation causing PV-like erythrocytosis in 3 generations. Amelioration by Ropeg-Interferon

Polycythemia vera (PV) is a clonal disorder arising from the acquired somatic mutations of the JAK2 gene, including JAK2V617F or several others in exon 12. A 38-year-old female had a stroke at age 32 and found to have elevated hemoglobin, normal leukocytes, normal platelets, and tested negative for JAK2V617F and exon 12 mutations. Next generation sequencing revealed a novel mutation: JAK2R715T in the pseudokinase domain (JH2) at 47.5%. Its presence in her nail DNA confirmed a germline origin. Her mother and her son similarly had erythrocytosis and a JAK2R715T mutation. Computer modeling indicated gain-of-function JAK2 activity. The propositus and her mother had polyclonal myelopoiesis, ruling out another somatic mutation-derived clonal hematopoiesis. Some erythroid progenitors of all three generations grew without erythropoietin, a hallmark of PV. The in vitro reporter assay confirmed increased activity of the JAK2R715T kinase. Similar to PV, the JAK2R715T native cells have increased STAT5 phosphorylation, augmented transcripts of prothrombotic and inflammatory genes, and decreased KLF2 transcripts. The propositus was not controlled by hydroxyurea, and JAK2 inhibitors were not tolerated; however, Ropeginterferon-alfa-2b (Ropeg-IFN-α) induced a remission. Ropeg-IFN-α treatment also reduced JAK2 activity in the propositus, her mother and JAK2V617F PV subjects. We report dominantly inherited erythrocytosis secondary to a novel germline JAK2R715T gain-of-function mutation with many but not all comparable molecular features to JAK2V617F PV. We also document a previously unreported inhibitory mechanism of JAK2 signaling by Ropeg-IFN-α.

Advances in Molecular Understanding of Polycythemia Vera, Essential Thrombocythemia, and Primary Myelofibrosis: Towards Precision Medicine

Myeloproliferative neoplasms (MPNs), including Polycythemia Vera (PV), Essential Thrombocythemia (ET), and Primary Myelofibrosis (PMF), are characterized by the clonal proliferation of hematopoietic stem cells leading to an overproduction of hematopoietic cells. The last two decades have seen significant advances in our understanding of the molecular pathogenesis of these diseases, with the discovery of key mutations in the JAK2, CALR, and MPL genes being pivotal. This review provides a comprehensive update on the molecular landscape of PV, ET, and PMF, highlighting the diagnostic, prognostic, and therapeutic implications of these genetic findings. We delve into the challenges of diagnosing and treating patients with prognostic mutations, clonal evolution, and the impact of emerging technologies like next-generation sequencing and single-cell genomics on the field. The future of MPN management lies in leveraging these molecular insights to develop personalized treatment strategies, aiming for precision medicine that optimizes outcomes for patients. This article synthesizes current knowledge on molecular diagnostics in MPNs, underscoring the critical role of genetic profiling in enhancing patient care and pointing towards future research directions that promise to further refine our approach to these complex disorders.

Acute myeloid leukemias with JAK2/STAT mutations are associated with PD-L1 upregulation

Even though overexpression of the immune checkpoint protein, programmed cell death ligand-1 (PD-L1), is observed in solid tumors, its expression patterns in acute myeloid leukemia remain understudied. As activation of the JAK/STAT pathway has been shown to enhance PD-L1 expression in preclinical models, we evaluated biopsies from AML patients with activating mutations in JAK2/STATs. PD-L1 expression was significantly upregulated in JAK2/STAT mutant cases when compared to JAK2 wildtype controls as demonstrated by PD-L1 immunohistochemistry staining and quantified using the combined positive score (CPS) system. There is significant overexpression of phosphorylated STAT3 expression in patients with oncogenic JAK2 activation and a positive correlation between p-STAT3 and PD-L1 expression. In conclusion, we demonstrate the CPS scoring system could be applied as a quantitative measure of PD-L1 expression in leukemias and that JAK2/STATs mutant AML can be potential candidates for checkpoint inhibitor trials.

Triple-Negative Primary Myelofibrosis: A Bone Marrow Pathology Group Study

Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm driven by canonical gene mutations in JAK2, CALR, or MPL in >80% of the cases. PMF that lacks these canonical alterations is termed triple-negative PMF (TN-PMF). The pathologic and genetic characteristics of TN-PMF compared with those of conventional PMF with canonical driver mutations (DM-PMF) have not been well studied. We aimed to identify clinicopathologic and molecular genetic differences between patients with TN-PMF (n = 56) and DM-PMF (n = 89), all of whom fulfilled the 2016 World Health Organization diagnostic criteria for PMF. Compared with the control group, patients in the TN-PMF group were more likely to have thrombocytopenia and less likely to have organomegaly. The bone marrow in patients with TN-PMF showed fewer granulocytic elements and more frequent dyserythropoiesis. Cytogenetic analysis showed a higher incidence of trisomy 8. Targeted next-generation sequencing revealed a lower frequency of ASXL1 mutations but enrichment of ASXL1/SRSF2 comutations. Our findings demonstrated several clinicopathologic and molecular differences between TN-PMF and DM-PMF. These findings, particularly the observed mutation profile characterized by a higher frequency of ASXL1 and SRSF2 comutation, suggest that at least a subset of TN-PMF may be pathogenetically different from DM-PMF, with potential prognostic implications.

Clinicopathologic characteristics of myeloproliferative neoplasms with JAK2 exon 12 mutation

The presence of JAK2 exon 12 mutation was included by the 2016 World Health Organization (WHO) Classification as one of the major criteria for diagnosing polycythemia vera (PV). Few studies have evaluated the clinical presentation and bone marrow morphology of these patients and it is unclear if these patients fulfill the newly published criteria of 5th edition WHO or The International Consensus Classification (ICC) criteria for PV. Forty-three patients with JAK2 exon 12 mutations were identified from the files of 7 large academic institutions. Twenty patients had complete CBC and BM data at disease onset. Fourteen patients met the diagnostic criteria for PV and the remaining six patients were diagnosed as MPN-U. At diagnosis, 9/14 patients had normal WBC and platelet counts (isolated erythrocytosis/IE subset); while 5/14 had elevated WBC and/or platelets (polycythemic /P subset). We found that hemoglobin and hematocrit tended to be lower in the polycythemia group. Regardless of presentation (P vs IE), JAK2 deletion commonly occurred in amino acids 541-544 (62 %). MPN-U patients carried JAK2 exon 12 mutation, but did not fulfill the criteria for PV. Half of the patients had hemoglobin/hematocrit below the diagnostic threshold for PV, but showed increased red blood cell count with low mean corpuscular volume (56-60 fL). Three cases lacked evidence of bone marrow hypercellularity. In summary, the future diagnostic criteria for PV may require a modification to account for the variant CBC and BM findings in some patients with JAK2 exon 12 mutation.

Molecular Genetics of Thrombotic Myeloproliferative Neoplasms: Implications in Precision Oncology

Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) include polycythaemia vera, essential thrombocythaemia, and primary myelofibrosis. Unlike monogenic disorders, a more complicated series of genetic mutations are believed to be responsible for MPN with various degrees of thromboembolic and bleeding complications. Thrombosis is one of the early manifestations in patients with MPN. To date, the driver genes responsible for MPN include JAK2, CALR, MPL, TET2, ASXL1, and MTHFR. Affords have been done to elucidate these mutations and the incidence of thromboembolic events. Several lines of evidence indicate that mutations in JAK2, MPL, TET2 and ASXL1 gene and polymorphisms in several clotting factors (GPIa, GPIIa, and GPIIIa) are associated with the occurrence and prevalence of thrombosis in MPN patients. Some polymorphisms within XRCC1, FBG, F2, F5, F7, F12, MMP9, HPA5, MTHFR, SDF-1, FAS, FASL, TERT, ACE, and TLR4 genes may also play a role in MPN manifestation. This review aims to provide an insightful overview on the genetic perspective of thrombotic complications in patients with MPN.

The differences of hemogram, myelogram, and driver gene mutations in classic myeloproliferative neoplasms

The aim of this study was to explore and compare routine blood features and pathological characteristics of bone marrow tissues in essential thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis, prefibrotic stage (prePMF) and overt fibrotic stage (overtPMF), and the correlation between common driver gene mutations and clinical manifestations of myeloproliferative neoplasms (MPN). Methods: We analyzed 259 MPN patients treated at Tongji Hospital of Huazhong University of Science and Technology from January 2016 to December 2020. Results: Among ET, PV, prePMF, and overtPMF, the median leukocyte counts of PV and prePMF were significantly higher than those of ET. The average hemoglobin level of overtPMF was significantly lower than that of ET, PV, and prePMF. ET and prePMF had higher platelet counts than PV and overtPMF, whereas ET had the lowest platelet distribution width. Regarding hematopoietic tissues in the bone marrow, enlarged megakaryocytes were easily found in ET, PV, and prePMF, whereas the average diameter of megakaryocytes in prePMF was smaller than in ET, and PV showed various sizes of megakaryocytes. An increased M/E ratio and dilation of sinus were seen more frequently in PMF. Additionally, JAK2-positive patients tended to have significantly higher leukocyte counts than CALR-positive patients in ET and PMF.

The Contribution of JAK2 46/1 Haplotype in the Predisposition to Myeloproliferative Neoplasms

Haplotype 46/1 (GGCC) consists of a set of genetic variations distributed along chromosome 9p.24.1, which extend from the Janus Kinase 2 gene to Insulin like 4. Marked by four jointly inherited variants (rs3780367, rs10974944, rs12343867, and rs1159782), this haplotype has a strong association with the development of BCR-ABL1-negative myeloproliferative neoplasms (MPNs) because it precedes the acquisition of the JAK2V617F variant, a common genetic alteration in individuals with these hematological malignancies. It is also described as one of the factors that increases the risk of familial MPNs by more than five times, 46/1 is associated with events related to inflammatory dysregulation, splenomegaly, splanchnic vein thrombosis, Budd-Chiari syndrome, increases in RBC count, platelets, leukocytes, hematocrit, and hemoglobin, which are characteristic of MPNs, as well as other findings that are still being elucidated and which are of great interest for the etiopathological understanding of these hematological neoplasms. Considering these factors, the present review aims to describe the main findings and discussions involving the 46/1 haplotype, and highlights the molecular and immunological aspects and their relevance as a tool for clinical practice and investigation of familial cases.

Myeloproliferative Neoplasms, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology

The classic Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) consist of myelofibrosis, polycythemia vera, and essential thrombocythemia and are a heterogeneous group of clonal blood disorders characterized by an overproduction of blood cells. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for MPN were developed as a result of meetings convened by a multidisciplinary panel with expertise in MPN, with the goal of providing recommendations for the management of MPN in adults. The Guidelines include recommendations for the diagnostic workup, risk stratification, treatment, and supportive care strategies for the management of myelofibrosis, polycythemia vera, and essential thrombocythemia. Assessment of symptoms at baseline and monitoring of symptom status during the course of treatment is recommended for all patients. This article focuses on the recommendations as outlined in the NCCN Guidelines for the diagnosis of MPN and the risk stratification, management, and supportive care relevant to MF.

Assessment of relation between JAK2 gene and thrombosis in myeloproliferative neoplasms

Background Thrombotic complications are the most considerable etiology causing morbidity and mortality in patients with philadelphia (Ph) negative myeloproliferative neoplasms (MPN). There are many studies evaluating the association of JAK2 mutation and risk of thrombosis in MPN with inconclusive results. We also investigated the relation between JAK2 mutation in all Ph negative MPN and thrombosis. Material and Methods Thrombotic events and demographic features of 177 patients with Ph negative MPN were evaluated retrospectively. Results JAK2 V617 F mutation was detected in 57% of patients with essential thrombocythemia (ET), %90.3 of pateints with polycythemia vera (PV), 100% of pateints with primary myelofibrosis (PMF). Thrombotic complications occured more frequently with JAK2 mutation in all MPN patients than without (p=0.014). In JAK 2 mutation positive groups, the median age, thrombosis risk scores and leucocyte values are higher, splenomegaly and arterial and/or venous thrombosis are detected more frequently (p

Thrombotic and Atherogenetic Predisposition in Polyglobulic Donors

This work analyses the results of research regarding the predisposition of genetic hematological risks associated with secondary polyglobulia. The subjects of the study were selected based on shared laboratory markers and basic clinical symptoms. JAK2 (Janus Kinase 2) mutation negativity represented the common genetic marker of the subjects in the sample of interest. A negative JAK2 mutation hypothetically excluded the presence of an autonomous myeloproliferative disease at the time of detection. The parameters studied in this work focused mainly on thrombotic, immunological, metabolic, and cardiovascular risks. The final goal of the work was to discover the most significant key markers for the diagnosis of high-risk patients and to exclude the less important or only complementary markers, which often represent a superfluous economic burden for healthcare institutions. These research results are applicable as a clinical guideline for the effective diagnosis of selected parameters that demonstrated high sensitivity and specificity. According to the results obtained in the present research, groups with a high incidence of mutations were evaluated as being at higher risk for polycythemia vera disease. It was not possible to clearly determine which of the patients examined had a higher risk of developing the disease as different combinations of mutations could manifest different symptoms of the disease. In general, the entire study group was at risk for manifestations of polycythemia vera disease without a clear diagnosis. The group with less than 20% incidence appeared to be clinically insignificant for polycythemia vera testing and thus there is a potential for saving money in mutation testing. On the other hand, the JAK V617F (somatic mutation of JAK2) parameter from this group should be investigated as it is a clear exclusion or confirmation of polycythemia vera as the primary disease.

Genetic Background of Polycythemia Vera

Polycythemia vera belongs to myeloproliferative neoplasms, essentially by affecting the erythroblastic lineage. JAK2 alterations have emerged as major driver mutations triggering PV-phenotype with the V617F mutation detected in nearly 98% of cases. That’s why JAK2 targeting therapeutic strategies have rapidly emerged to counter the aggravation of the disease. Over decades of research, to go further in the understanding of the disease and its evolution, a wide panel of genetic alterations affecting multiple genes has been highlighted. These are mainly involved in alternative splicing, epigenetic, miRNA regulation, intracellular signaling, and transcription factors expression. If JAK2 mutation, irrespective of the nature of the alteration, is known to be a crucial event for the disease to initiate, additional mutations seem to be markers of progression and poor prognosis. These discoveries have helped to characterize the complex genomic landscape of PV, resulting in potentially new adapted therapeutic strategies for patients concerning all the genetic interferences.

[Clinical and laboratory features compared between JAK2 exon12 and JAK2 V617F mutated polycythemia vera]

Objective: To compare clinical and laboratory features between JAK2 exon12 and JAK2 V617F mutated polycythemia vera (PV) . Method: We collected data from 570 consecutive newly-diagnosed subjects with PV and JAK2 mutation, and compared clinical and laboratory features between patients with JAK2 exon12 and JAK2 V617F mutation. Results: 543 (95.3%) subjects harboured JAK2 V617F mutation (JAK2 V617F cohort) , 24 (4.2%) harboured JAK2 exon12 mutations (JAK2 exon12 cohort) , and 3 (0.5%) harboured JAK2 exon12 and JAK2 V617F mutations. The mutations in JAK2 exon12 including deletion (n=10, 37.0%) , deletion accompanied insertion (n=10, 37.0%) , and missense mutations (n=7, 25.9%) . Comparing with JAK2 V617F cohort, subjects in JAK2 exon12 cohort were younger [median age 50 (20-73) years versus 59 (25-91) years, P=0.040], had higher RBC counts [8.19 (5.88-10.94) ×10(12)/L versus 7.14 (4.11-10.64) ×10(12)/L, P<0.001] and hematocrit [64.1% (53.7-79.0%) versus 59.6% (47.2%-77.1%) , P=0.001], but lower WBC counts [8.29 (3.2-18.99) ×10(9)/L versus 12.91 (3.24-38.3) ×10(9)/L, P<0.001], platelet counts [313 (83-1433) ×10(9)/L versus 470 (61-2169) ×10(9)/L, P<0.001] and epoetin [0.70 (0.06-3.27) versus 1.14 (0.01-10.16) IU/L, P=0.002] levels. We reviewed bone marrow histology at diagnosis in 20 subjects with each type of mutation matched for age and sex. Subjects with JAK2 exon12 mutations had fewer loose megakaryocyte cluster (40% versus 80%, P=0.022) compared with subjects with JAK2 V617F. The median follow-ups were 30 months (range 4-83) and 37 months (range 1-84) for cohorts with JAK2 V617F and JAK2 exon12, respectively. There was no difference in overall survival (P=0.422) and thrombosis-free survival (P=0.900) . Conclusions: Compared with patients with JAK2 V617F mutation, patients with JAK2 exon12 mutation were younger, and had more obvious erythrocytosis and less loose cluster of megakaryocytes.

[The relationship between symptom burden and hematologic responses after treatment with interferon/hydroxyurea in patients with polycythemia vera]

Objective: To explore the relationship between symptom burden and hematologic responses after treatment with interferon and/or hydroxyurea in patients with polycythemia vera (PV) . Methods: Hematologic responses after continuous treatment with interferon and/or hydroxyurea for six months were evaluated in 190 patients with PV using the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (MPN-10 score) . In all patients, the PV diagnosis was based on the 2016 World Health Organization diagnostic definitions. Results: The study cohort comprised 93 (48.9% ) male and 97 (51.1% ) female patients. The median age at the time of MPN-10 assessment was 60 (32-82) years. The median MPN-10 score of the entire cohort was 9 (range, 0-67) . The median MPN-10 score of patients treated with interferon plus hydroxyurea (n=27) was 11 (0-67) , which was significantly higher than those of patients treated with interferon only (n=64) (6[0-56], P=0.019) or hydroxyurea only (n=99) (9[0-64], P=0.047) , whereas the median MPN-10 score was not significantly different between those treated with interferon only and hydroxyurea only (P=0.421) . The rate of severe symptom burden (i.e., any single symptom burden score ≥ 7 and/or total score ≥ 44) was 28.9% (55/190) in the entire cohort, whereas the rate of severe symptom burden was not significantly different among the interferon only (23.4% ) , hydroxyurea only (29.3% ) , and interferon plus hydroxyurea (40.7% ) groups (P>0.05 for all two-group comparisons) . When evaluating MPN-10 score, 37.4% (71/190) of the patients achieved complete hematologic remission (CHR) . Only 28.9% (55/190) patients had adequate disease control, defined as CHR without severe symptom burden. Reasons for inadequate disease control were evaluating blood counts alone, severe symptom burden alone, and evaluating blood counts accompanied with severe symptom burden in 42.1% (80/190) , 8.4% (16/190) , and 20.5% (39/190) of the patients, respectively. Compared to the patients with a platelet count ≤ 400×10(9)/L, those with a platelet count > 400×10(9)/L had a significantly higher rate of severe symptom burden (40.8% [20/49] vs 24.8% [35/141], P=0.044) and a higher median MPN-10 score (14[0-67] vs 7[0-56], P=0.038) . Platelet count > 400×10(9)/L was associated with an increased risk of severe symptom burden (hazard ratio, 2.089; 95% confidence interval, 1.052-4.147, P=0.035) . Conclusions: Symptoms related to disease after treatment with interferon and/or hydroxyurea were rather universal in patients with PV. Some patients still experienced severe symptom burden despite achieving CHR. Platelet count > 400×10(9)/L was associated with an increased risk of severe symptom burden in patients with PV treated with interferon and/or hydroxyurea.

Recent Advances in the Use of Molecular Analyses to Inform the Diagnosis and Prognosis of Patients with Polycythaemia Vera

Genetic studies in the past decade have improved our understanding of the molecular basis of the BCR-ABL1-negative myeloproliferative neoplasm (MPN) polycythaemia vera (PV). Such breakthroughs include the discovery of the JAK2V617F driver mutation in approximately 95% of patients with PV, as well as some very rare cases of familial hereditary MPN caused by inherited germline mutations. Patients with PV often progress to fibrosis or acute myeloid leukaemia, both associated with very poor clinical outcome. Moreover, thrombosis and major bleeding are the principal causes of morbidity and mortality. As a result of increasingly available and economical next-generation sequencing technologies, mutational studies have revealed the prognostic relevance of a few somatic mutations in terms of thrombotic risk and risk of transformation, helping to improve the risk stratification of patients with PV. Finally, knowledge of the molecular basis of PV has helped identify targets for directed therapy. The constitutive activation of the tyrosine kinase JAK2 is targeted by ruxolitinib, a JAK1/JAK2 tyrosine kinase inhibitor for PV patients who are resistant or intolerant to cytoreductive treatment with hydroxyurea. Other molecular mechanisms have also been revealed, and numerous agents are in various stages of development. Here, we will provide an update of the recent published literature on how molecular testing can improve the diagnosis and prognosis of patients with PV and present recent advances that may have prognostic value in the near future.

Lab tests for MPN

Molecular laboratory investigations for myeloproliferative neoplasm (MPN) can ideally be divided into two distincts groups, those for the detection of the BCR-ABL rearrangement (suspect of chronic myeloid leukemia) and those for the variants determination of the driver genes of the negative Philadelphia forms (MPN Ph neg). The BCR-ABL detection is based on RT-Polymerase Chain Reaction techniques and more recently on droplet digital PCR (ddPCR). For this type of analysis, combined with chromosome banding analysis (CBA) and Fluorescent in situ hybridization (FISH), it is essential to quantify BCR-ABL mutated copies by standard curve method. The investigation on driver genes for MPN Ph neg forms includes activity for erythroid forms such as Polycythemia Vera (test JAK2V617F and JAK2 exon 12), for non-erythroid forms such as essential thrombocythemia and myelofibrosis (test JAK2V617F, CALR exon 9, MPL exon 10), for "atypical" ones such as mastocytosis (cKIT D816V test) and for hypereosinophilic syndrome (FIP1L1-PDGFRalpha test). It's crucial to assign prognosis value through calculating allelic burden of JAK2 V617F variant and determining CALR esone 9 variants (type1/1like, type2/2like and atypical ones). A fundamental innovation for investigating triple negative cases for JAK2, CALR, MPL and for providing prognostic score is the use of Next Generation Sequencing panels containing high molecular risk genes as ASXL1, EZH2, TET2, IDH1/IDH2, SRSF2. This technique allows to detect additional or subclonal mutations which are usually acquired in varying sized sub-clones of hematopoietic progenitors. These additional variants have a prognostic significance and should be indagated to exclude false negative cases.

Polycythemia Vera (PV): Update on Emerging Treatment Options

Polycythemia Vera (PV) is a chronic myeloproliferative neoplasm characterized by exuberant red cell production leading to a broad range of symptoms that compromise quality of life and productivity of patients. PV reduces survival expectation, primarily due to thrombotic events, transformation to blast phase and post-PV myelofibrosis or to development of second cancers, which are associates with poor prognosis. Current therapeutic first line recommendations based on risk adapted classification divided patients into two groups, according to age (< or >60 years) and presence of prior thrombotic events. Low-risk patients (age <60 years and no prior history of thrombosis) should be treated with aspirin (81-100 mg/d) and phlebotomy, to maintain hematocrit <45%. High-risk patients (age >60 years and/or prior history of thrombosis), in addition to aspirin and phlebotomies, should receive cytoreductive therapy in order to reduce thrombotic risk. Nowadays hydroxyurea still remains the cytoreductive agent of first choice, reserving Interferon to young patients or childbearing women. During the last years, ruxolitinib emerged as a new treatment in PV patients, as second line therapy: it appeared especially effective in patients with severe pruritus, symptomatic splenomegaly, or post-PV myelofibrosis symptoms. Currently, in PV treatment, several molecules have been tested or are under investigation. At present, the drug that has shown the most encouraging results is givinostat.

Applications of next-generation sequencing in hematologic malignancies

In the last decade, next-generation sequencing (NGS) has rapidly progressed from a research method to a core component of standard-of-care clinical testing. In oncology, tumor sequencing provides a critical tool to detect somatic driver mutations that not only characterize disease but also impact therapeutic decision-making. Here, we review the important role of NGS in the evaluation of hematopoietic neoplasms. We discusstechnical and practical considerations relevant in somatic mutation testing, emphasizing issues unique to blood cancers. Then, we describe how NGS data is being used to facilitate diagnosis, inform prognosis, guide therapy selection, and even monitor disease. This broad overview highlights the transformative impacts NGS data provides throughout the clinical course of patients with hematologic malignancies.

Polycythaemia vera: molecular genetics, diagnostics and therapeutics

Polycythaemia vera is one of several classical myeloproliferative neoplasms that may occur in a juvenile onset or late-onset adult forms. It is linked to specific genetic mutations that cause a deleterious elevation in the patient's red cell mass. The discourse on genetics includes an exposé on the molecular biology of the disease and how a shared JAK2 V617F mutation can co-exist among three distinct neoplasms. Concepts of genetics and immunology help define the origin and behaviour of the disease: the tracking of allele burdens of mutations (genetic dosage), the timing or order of acquired mutations, the import of bystander mutations and the onco-inflammatory response; all theories are invoked to explain the progression of disease severity and potential transformational leukaemia. The World Health Organization's diagnostic criteria are accessed to focus on the subtleties of the Hb laboratories and sifting through the challenging listing of differential diagnoses that mimic PV, and our report includes an overview of manual and automated phlebotomy (erythrocytapheresis) procedures, enumerating their clinical indications, significance of temporary phlebotomy resistance and optimizing safety/ efficacy, quality and cost. Stratification of low and high-risk disease distinguishes when to commence chemo-cytoreductive therapy in the high-risk patient to prevent thrombotic complications. Drug resistance is circumvented by artfully switching drugs or using novel drug designs.

The 2020 revision of the guidelines for the management of myeloproliferative neoplasms

In 2016, the World Health Organization revised the diagnostic criteria for myeloproliferative neoplasms (MPNs) based on the discovery of disease-driving genetic aberrations and extensive analysis of the clinical characteristics of patients with MPNs. Recent studies have suggested that additional somatic mutations have a clinical impact on the prognosis of patients harboring these genetic abnormalities. Treatment strategies have also advanced with the introduction of JAK inhibitors, one of which has been approved for the treatment of patients with myelofibrosis and those with hydroxyurea-resistant or intolerant polycythemia vera. Recently developed drugs aim to elicit hematologic responses, as well as symptomatic and molecular responses, and the response criteria were refined accordingly. Based on these changes, we have revised the guidelines and present the diagnosis, treatment, and risk stratification of MPNs encountered in Korea.

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.

Polycythemia vera: the current status of preclinical models and therapeutic targets

INTRODUCTION

Polycythemia vera (PV) is the most common myeloproliferative neoplasm (MPN). PV is characterized by erythrocytosis, leukocytosis, thrombocytosis, increased hematocrit, and hemoglobin in the peripheral blood. Splenomegaly and myelofibrosis often occur in PV patients. Almost all PV patients harbor a mutation in the JAK2 gene, mainly represented by the JAK2^V617F point mutation.

AREAS COVERED

This article examines the recent in vitro and in vivo available models of PV and moreover, it offers insights on emerging biomarkers and therapeutic targets. The evidence from mouse models, resembling a PV-like phenotype generated by different technical approaches, is discussed. The authors searched PubMed, books, and clinicaltrials.gov for original and review articles and drugs development status including the terms Myeloproliferative Neoplasms, Polycythemia Vera, erythrocytosis, hematocrit, splenomegaly, bone marrow fibrosis, JAK2^V617F, Hematopoietic Stem Cells, MPN cytoreductive therapy, JAK2 inhibitor, histone deacetylase inhibitor, PV-like phenotype, JAK2^V617F BMT, transgenic JAK2^V617F mouse, JAK2 physiologic promoter.

EXPERT OPINION

Preclinical models of PV are valuable tools for enabling an understanding of the pathophysiology and the molecular mechanisms of the disease. These models provide new biological insights on the contribution of concomitant mutations and the efficacy of novel drugs in a 'more faithful' setting. This may facilitate an enhanced understanding of pathogenetic mechanisms and targeted therapy.

Essential thrombocythemia A retrospective case series

BACKGROUND

Essential thrombocythemia (ET) is rare in children, and pediatric guidelines are lacking. Therefore, we aimed to evaluate ET diagnosis and treatment in a pediatric cohort.

PROCEDURE

Data of patients with ET from three hospitals were reviewed. Molecular diagnosis included JAK2V617F, CALR, and MPL mutations. Patients were evaluated for acquired von Willebrand syndrome (AVWS). Follow-up included clinical symptoms, adverse events, and treatment.

RESULTS

Twelve children (median age: 8 years, range 1-14.5) were included. Mean lag period between the first documentation of thrombocytosis until ET diagnosis was 36 months. Six patients were positive for JAK2V617F and two for CALR mutations. In six of nine patients, AVWS was diagnosed. At diagnosis, only 33% of patients started therapy with aspirin (n = 4) and hydroxyurea (n = 2). In three of eight untreated patients, therapy was added during follow-up. The cohort was followed for a median of 32.5 months (range: 4-108 months). Clinical follow-up disclosed vascular complications in 4 of 12 patients (deep vein thrombosis, n = 1; transient ischemic attack, n = 3). Two females experienced excessive bleeding; both were diagnosed with AVWS. Neither leukemia nor myelofibrosis evolved in our cohort.

CONCLUSION

Increased awareness to pediatric ET is warranted, as delayed diagnosis is common. Compared to adults, AVWS may be more prevalent among children with ET.

JAK2 exon 12 mutations in cases with JAK2V617F-negative polycythemia vera and primary myelofibrosis

Molecular detection of JAK2 mutation (V617F or exon 12) is included as a major diagnostic criterion for polycythemia vera (PV) by the WHO 2016 guidelines. JAK2 exon 12 mutations are seen in about 2-5% of JAK2V617F-negative cases of PV. Mutations in JAK2 cause constitutive activation of JAK-STAT pathway which results in variable phenotypes. PV patients with exon 12 mutations in JAK2 present characteristically with erythrocytosis. There are limited reports describing the spectrum of JAK2 exon12 mutations in myeloproliferative neoplasms (MPNs). Here, we describe the characteristics of a series of MPN patients with mutations in exon 12 of JAK2 of which two were novel variants associated with polycythemia. Interestingly, we noted two patients presenting as myelofibrosis having JAK2 exon 12 mutations.

Myeloproliferative and lymphoproliferative disorders: State of the art

Myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are clonal disorders complicated mainly by vascular events and transformation to myelofibrosis (for PV and ET) or leukemia. Although secondary malignancies, in particular, lymphoproliferative disorders (LPNs), are rare, they occur at a higher frequency than found in the general population, and there has been recent scientific discussion regarding a hypothetical relationship between treatment with JAK inhibitors in MPN and the risk of development of LPN. This has prompted increased interest regarding the coexistence of MPN and LPN. This review focuses on the role of JAK2 and the JAK/STAT pathway in MPN and LPN, whether there is a role for the genetic background in the occurrence of both MPN and LPN and whether there is a role for cytoreductive drugs in the occurrence of both MPN and LPN. Furthermore, whether an increased risk of lymphoma development is limited to patients who receive the JAK inhibitor ruxolitinib, is a more general phenomenon that occurs following JAK1/2 inhibition or is associated with preferential JAK1 or JAK2 targeting is discussed.

The role of driver mutations in myeloproliferative neoplasms: insights from mouse models

High frequency of JAK2V617F or CALR exon 9 mutations is a main molecular feature of myeloproliferative neoplasms (MPNs). Analysis of mouse models driven by these mutations suggests that they are a direct cause of MPNs and that the expression levels of the mutated genes define the disease phenotype. The function of MPN-initiating cells has also been elucidated by these mouse models. Such mouse models also play an important role in modeling disease to investigate the effects and action mechanisms of therapeutic drugs, such as JAK2 inhibitors and interferon α, against MPNs. The mutation landscape of hematological tumors has already been clarified by next-generation sequencing technology, and the importance of functional analysis of mutant genes in vivo should increase further in the future.

Clinical and molecular profile of a Brazilian cohort of patients with classical BCR-ABL1-negative myeloproliferative neoplasms

Background

The classical BCR-ABL1-negative myeloproliferative neoplasms (MPNs) are Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF). In developing countries, there are few reports that truly reveal the clinical setting of these patients. Therefore, we aimed to characterize a single center MPN population with a special focus on the correct diagnosis based on the recent review of the WHO criteria for the diagnosis of myeloid neoplasms.

Methods

This retrospective study analyzed data from medical records of patients with classical BCR-ABL1-negative MPNs diagnosed from January 1997 to October 2017 and followed at the University Hospital of Ribeirão Preto Medical School.

Results

A total of 162 patients were assessed, 61 with PV, 50 with ET, and 51 with PMF. The mutational status analysis revealed that 113 (69.3%) harbored the JAK2V617F mutation, 23 (14.1%), the CALR mutation, and 12 (7.4%) had a triple-negative status. None of the patients were found to have mutations on the thrombopoietin receptor gene (MPL), including some ET and PMF patients who were not tested. Among the PV patients, 57 (93.5%) were positive for the JAK2V617F mutation, one (1.6%) presented an in-frame deletion JAK2 exon 12 mutation and one (1.6%) presented a missense JAK2 exon 9 mutation, not previously described. The overall survival was lower in the triple-negative patients with PMF, when compared to the JAK2V617F or CALR-mutated (p = 0.002).

Conclusion

The frequency of somatic mutations and survival in our cohort, stratified according to the respective disease, was consistent with the literature data, despite some limitations. Further prospective epidemiological studies of MPN cohorts are encouraged in developing countries.

The molecular details of cytokine signaling via the JAK/STAT pathway

More than 50 cytokines signal via the JAK/STAT pathway to orchestrate hematopoiesis, induce inflammation and control the immune response. Cytokines are secreted glycoproteins that act as intercellular messengers, inducing proliferation, differentiation, growth, or apoptosis of their target cells. They act by binding to specific receptors on the surface of target cells and switching on a phosphotyrosine-based intracellular signaling cascade initiated by kinases then propagated and effected by SH2 domain-containing transcription factors. As cytokine signaling is proliferative and often inflammatory, it is tightly regulated in terms of both amplitude and duration. Here we review molecular details of the cytokine-induced signaling cascade and describe the architectures of the proteins involved, including the receptors, kinases, and transcription factors that initiate and propagate signaling and the regulatory proteins that control it.

Disruption of R867 and Y613 interaction plays key roles in JAK2 R867Q mutation caused acute leukemia

Janus tyrosine kinase 2 (JAK2) mediates downstream signaling of cytokine receptors in all hematological lineages, constitutively active somatic JAK2 mutations were important for the leukemogenesis of acute leukemia (AL). The JAK2 R867Q somatic mutation is detected in a subset of AL patients. However, roles of JAK2 R867Q mutation in the pathogenesis of AL remain unclear. In this study, homology modeling analysis showed that loss of interaction between R867 and Y613 disrupted the JAK2 JH1/JH2 domain's interactions was responsible for its activation. JAK2 R867Q and mutations (R867A and R867G) abolished this interaction caused JAK2 constitutive activation. While, mutations (R867K, Y613E, R867K/Y613E) repairing this interaction reduced JAK2 R867Q mutation's activity. Furthermore, our studies showed that abolished R867 and Y613 interaction disrupted JH1/JH2 domains' interactions and led to JAK2 constitutive activation. More importantly, mutations (R867Q, R867A and R867G) disrupted this interaction enhanced the activity of JAK2-STAT5 pathway and the proliferation of Ba/F3 and MV4-11 cells. Further study showed that JAK2 R867Q mutation promoted the expression of proliferation marker and inhibited the differentiation marker of Ba/F3 and MV4-11 cells. Thus our studies provide clues in understanding the pathogenesis of JAK2 R867Q mutation in AL.

The role of the thrombopoietin receptor MPL in myeloproliferative neoplasms: recent findings and potential therapeutic applications

Introduction: Classical Myeloproliferative Neoplasms (MPNs) include three disorders: Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF). MPNs are associated with constitutive activation of JAK2 leading to persistent cell signaling downstream of the dimeric myeloid cytokine receptors due to mutations in three genes encoding JAK2, calreticulin (CALR) and the thrombopoietin (TPO) receptor (MPL or TPOR). CALR and MPL mutants induce JAK2 activation that depends on MPL expression, thus explaining why they induce megakaryocyte pathologies including ET and PMF, but not PV. In contrast, JAK2 V617F drives all three diseases as it induces persistent signaling via EPOR, G-CSFR (CSF3R) and MPL. Areas Covered: Here, we review how different pathogenic mutations of MPL are translated into active receptors by inducing stable dimerization. We focus on the unique role of MPL on the hematopoietic stem cell (HSC), explaining why MPL is indispensable for the development of all MPNs. Last but not least, we describe how CALR mutants are pathogenic via binding and activation of MPL. Expert Opinion: Altogether, we believe that MPL is an important, but challenging, therapeutic target in MPNs that requires novel strategies to interrupt the specific conformational changes induced by each mutation or pathologic interaction without compromising the key functions of wild type MPL.

The Role of New Technologies in Myeloproliferative Neoplasms

The hallmark of BCR-ABL1-negative myeloproliferative neoplasms (MPNs) is the presence of a driver mutation in JAK2, CALR, or MPL gene. These genetic alterations represent a key feature, useful for diagnostic, prognostic and therapeutical approaches. Molecular biology tests are now widely available with different specificity and sensitivity. Recently, the allele burden quantification of driver mutations has become a useful tool, both for prognostication and efficacy evaluation of therapies. Moreover, other sub-clonal mutations have been reported in MPN patients, which are associated with poorer prognosis. ASXL1 mutation appears to be the worst amongst them. Both driver and sub-clonal mutations are now taken into consideration in new prognostic scoring systems and may be better investigated using next generation sequence (NGS) technology. In this review we summarize the value of NGS and its contribution in providing a comprehensive picture of mutational landscape to guide treatment decisions. Finally, discussing the role that NGS has in defining the potential risk of disease development, we forecast NGS as the standard molecular biology technique for evaluating these patients.

Detection of Exon 12 and 14 Mutations in Janus Kinase 2 Gene Including a Novel Mutant in V617F Negative Polycythemia Vera Patients from Pakistan

The most frequently reported genetic aberration among polycythemia vera (PV) patients is a gain of function mutation V617F in exon 14 of Janus kinase 2 (JAK2) gene. However in many investigations, V617F negative PV patients have been reported to harbor mutations in JAK 2 exon 12. We investigated 24 patients with PV (diagnosed following 2016 WHO guidelines) to detect V617F mutation through allele specific PCR. The frequency of which was found to be 19/24 (79.2 %). Later on JAK2 exon 12 and 14 was amplified by conventional PCR in V617F negative patients and subjected to sequence analysis. A total of 03 mutated sites in exon 12 were detected in only two V617F-negative patients 2/5 (40%). All three substitutions were heterozygous i.e. F537F/I found in both patients and R528R/T, which is a novel mutation. In addition, one patient 1/5 (10%) manifested amino acid substitution V617A in JAK2 exon 14. Hematological parameters of individuals harboring mutations do not vary significantly than rest of the PV patients. Previous history and 2.3 years of follow-up studies reveal 15-year survival of V617F positive patients (n=19) to be 76%, while it is 94% for wild type V617 patients (n=05). Mean TLC of the patient cohort was 17.6± 9.1 x 109/L, mean platelet count was 552± 253 x 109/L, mean hemoglobin was 16.9± 3.2 g/dl, mean corpuscular volume (MCV) was 77.2± 13.0 fl and mean corpuscular hemoglobin (MCH) was 25.6± 3.9 pg. This is the very first attempt from Pakistan to screen JAK2-exon 12 mutations in PV patients. We further aim to investigate Jak2 exon 12 mutations in larger number of PV patients to assess their clinical relevance and role in disease onset, progression and transformation.

Unique Case of Myeloproliferative Neoplasm with Two Rare Clonal Abnormalities: Rare JAK2 Exon 12 Mutation and Rare e14a3 (b3a3) BCR/ABL Fusion Transcript

Myeloproliferative neoplasms (MPNs) are clonal disorders divided into Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) or Ph chromosome-negative MPNs. Co-occurrence of these disease entities is very rare and typically involves presence of common p190 or p210 BCR/ABL fusion transcript (responsible for CML) along with JAK2V617F mutation (most common driver mutation in Ph-negative MPNs). Because of the rarity of such cases, it is not clear if the outcomes are any different in these patients. In this article, we report a unique patient with polycythemia vera driven by a rare complex in-frame deletion-insertion mutation in JAK2 exon 12, and CML driven by uncommon p210 e14a3 (b3a3) BCR/ABL fusion transcript. We describe clinical and laboratory features, bone marrow pathology, treatment, and overall outcome.

Effects of JAK2 V556F mutation on the JAK2's activity, structural stability and the transformation of Ba/F3 cells

Although roles of somatic JAK2 mutations in clonally myeloproliferative neoplasms (MPNs) are well established, roles of germline JAK2 mutations in the pathogenesis of MPNs remain unclear. Recently, a novel activating, germline JAK2 F556V mutation was identified and involved in the pathogenesis of MPNs, but, its pathogenesis mechanism was still unknown. In this study, homology models of JAK2 demonstrated that F556 located between two threonine residues which interacted with ATP phosphate groups by hydrogen bonds, Thr555 with the γ-phosphate and Thr557 with the β-phosphate in the active site of JAK2's JH2 domain. Moreover, the hydrogen bond between Thr557 and Arg715 played vital roles in sustaining the structural conformation of JH2's active site and JH1-JH2 domains' interactions. When F556 was replaced by other amino acids except Trp, the hydrogen bond, JH2 domain's structural conformation and JH1-JH2 domains' interactions disrupted for changing the helix between β2 and β3 strands which finally caused JAK2 activation. Mechanistic and functional studies showed that JAK2 F556V mutation disrupted JAK2 JH2 domain's activity, caused JAK2-STAT5 pathway activation and promoted the proliferation of BaF3 cells. Thus, our results herein may provide clues to understand the pathogenesis mechanism of JAK2 F556V mutation in the MPNs.

Roles of germline JAK2 activation mutation JAK2 V625F in the pathology of myeloproliferative neoplasms

Janus tyrosine kinase 2 (JAK2) mediates downstream signaling of cytokine receptors in all hematological lineages, constitutively active somatic JAK2 mutations play key roles in the pathology of myeloproliferative neoplasms (MPNs). Recently, germline JAK2 mutations are also associated with triple-negative MPNs. A novel germline mutation JAK2 V625F is reported to be involved in a subset of MPNs patients. However, the pathogenesis of this mutation caused MPN is still unclear. In this study, the homology models of JAK2 V625F showed that the newly formed interaction between F625 and Y613 disrupted the JAK2 JH1-JH2 domain interactions was responsible for its activation, when F625 and Y613 interaction was disrupted, its activity significantly decreased. While, when this interaction was repaired whether by forming hydrogen bond or salt bond, it would cause JAK2 activation. Biochemical studies also demonstrated that JAK2 V625F mutation led to JAK2-STAT5 pathway activation and promoted the proliferation of BaF3 cells. Thus, our results herein provide clues to understand the mechanism JAK2 V625F mutation caused MPNs and give information for the development of JAK2 mutation specific inhibitors.

Somatic Mutations in Philadelphia Chromosome-Negative Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPN) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). MPN are characterized by clonal proliferation of myeloid progenitors leading to erythrocytosis, thrombocytosis, or leukocytosis, and risk of hemorrhagic and thrombotic events, as well as myelofibrosis and blast transformation. The discovery of somatic mutations in MPN, namely JAK2 V617F, JAK2 exon 12, MPL, and CALR mutations, has permitted a more specific approach to diagnosis and treatment. The prevalence of JAK2 V617F mutations is higher than 95% in PV, 50%-75% in ET and 40%-75% in PMF. JAK2 exon 12 mutations are specific of PV. A 20%-30% of patients with ET and PMF present a CALR mutation. The screening of mutations strengthens the diagnosis of MPN since 97% of MPN have at least 1 somatic mutation. Interestingly, different mutations grant different phenotype and prognosis. Of particular importance, CALR mutations grant a favorable prognosis in ET and PMF, while ASXL1 mutations confer a poorer outcome. In fact, the use of CALR/ASXL1 status for the prognostication of patients has increased clinical value and is now suggested for guidance of therapy in PMF. The increasing importance of mutations in the management of MPN warrants a more frequent revision of current diagnostic criteria and prognostic models and a better understanding of the mechanisms leading to MPN subset differentiation.

HIF2A germline-mutation-induced polycythemia in a patient with VHL-associated renal-cell carcinoma

In this study, we report here a rare case of polycythemia and cRCC in the same patient, which may be helpful in understanding clinical features and molecular mechanisms underlying VHL-mutation-associated cRCC and polycythemia induced by germline mutation of HIF2A. Firstly, we identified a rare but well studied germline mutation resulting in polycythemia in HIF2A (c.1609G>A, p.Gly537Arg) in the blood of the patient and his daughter. Meanwhile, we identified an inactivating VHL mutation (c.391A>T, p.N131Y), as well as TP53 mutation(c.977A>T, p.E326V) and mTOR mutation(c.7498A>T, p.I2500F) in renal cancer tissue. Moreover, protein levels of VHL, HIF1A, HIF2A, EPO, and VEGF estimated by immunohistochemical staining substantiated hyperactivation of the oxygen-sensing pathway. In addition, we identified 158 somatic SNP/indel mutations, including 90 missense/nonsense/splice/stop-loss mutations by whole-exome sequencing (WES) of the tumor specimen and matched normal DNA.

Prognosis of Primary Myelofibrosis in the Genomic Era

Currently, prognostication in primary myelofibrosis (PMF) relies on the International Prognostic Scoring System (IPSS), dynamic IPSS (DIPSS), and DIPSS-plus, which incorporate age, blood counts, constitutional symptoms, circulating blasts, red cell transfusion need, and karyotype. Although the JAK2 V617F mutation was discovered a decade ago and MPL mutations shortly thereafter, it was the recent discovery of CALR mutations in the vast majority of JAK2/MPL-unmutated patients and recognition of the powerful impact of CALR mutations and triple-negative (JAK2/MPL/CALR-negative) status on outcome that set the stage for revision of traditional prognostic models to include molecular information. Additionally, the advent of next-generation sequencing has identified a host of previously unrecognized somatic mutations across hematologic malignancies. As in the myelodysplastic syndromes, the majority of common and prognostically informative mutations in PMF affect epigenetic regulation and mRNA splicing. Thus, a need has arisen to incorporate mutational information on genes such as ASXL1 and SRSF2 into risk stratification systems. Mutations in yet other genes appear to be important players in leukemic transformation, and new insights into disease pathogenesis are emerging. Finally, the number of prognostically detrimental mutations may affect both survival and response to ruxolitinib, which has significant implications for clinical decision making. In this review, we briefly summarize the prognostic models in use today and discuss in detail the somatic mutations commonly encountered in patients with PMF, along with their prognostic implications and role in leukemic transformation. Emerging prognostic models that incorporate new molecular information into existing systems or exclude clinical variables are also presented.

Atypical haematological presentation in a case of polycythaemia vera with a new variant mutation detected in exon 12: c.1605G>T (p.Met535Ile)

One of the major genetic insights into the pathogenesis of polycythaemia vera included the identification of the somatic point gain-of-function mutations in Janus kinase 2 gene-first JAK2V617F on exon 14, present in 95%-97% of the cases, and later on exon 12. In the literature, we can find some reported studies where different exon 12 mutations are identified. Unlike patients with JAK2V617F mutation in exon 14, the mutation at exon 12 is not usually associated with an increase in the three haematopoietic series (erythrocytosis, leucocytosis and thrombocytosis). It appears to be associated with a distinct syndrome, mostly characterised by isolated and more marked erythrocytosis, independently of the mutational variant. We report here the case of a patient who is JAK2exon 12 positive, presenting a novel mutation-c.1605G>T (p.Met535Ile)-associated with c.1612C>T (p.His538Tyr) mutation previously described, evidencing an atypical clinical phenotype.

Cytokine Signaling in Tumor Progression

Cytokines are molecules that play critical roles in the regulation of a wide range of normal functions leading to cellular proliferation, differentiation and survival, as well as in specialized cellular functions enabling host resistance to pathogens. Cytokines released in response to infection, inflammation or immunity can also inhibit cancer development and progression. The predominant intracellular signaling pathway triggered by cytokines is the JAK-signal transducer and activator of transcription (STAT) pathway. Knockout mice and clinical human studies have provided evidence that JAK-STAT proteins regulate the immune system, and maintain immune tolerance and tumor surveillance. Moreover, aberrant activation of the JAK-STAT pathways plays an undeniable pathogenic role in several types of human cancers. Thus, in combination, these observations indicate that the JAK-STAT proteins are promising targets for cancer therapy in humans. The data supporting this view are reviewed herein.