Over the past 35 years, interferons have been explored in various formulations for the management of Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), such as essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis, and remain a key tool in caring for patients with these diseases. These agents are excellent cytoreductive agents with high rates of hematologic response, are helpful in symptom management, and have a long track record of safety and manageable toxicities. More recently, they have shown promise in sustaining responses over many years, with associated reductions in driver mutations (JAK2, MPL, CALR) of these diseases, particularly in PV and ET. Since reductions in molecular mutant allele burden have been correlated with several response outcomes such as reductions in both thrombotic risk and disease progression, there is emerging proof that interferons may offer disease-modifying activity. These long-term benefits and their use as the preferred agent in young pregnant women who need cytoreduction make interferons often the first choice in young adult population who harbor a lifetime risk of progression. Looking forward, the prospect of sustained treatment-free responses, like chronic myeloid leukemia after deep molecular response, and normal life expectancy may also be on the frontier. Despite relative rookies such as JAK inhibitors in the MPN landscape, the veteran in the game, interferon, remains a key player.

Myelofibrosis (MF) is a myeloproliferative neoplasm that is accompanied by driver JAK2, CALR, or MPL mutations in more than 90% of cases, leading to constitutive activation of the JAK-STAT pathway. MF is a multifaceted disease characterized by trilineage myeloid proliferation with prominent megakaryocyte atypia and bone marrow fibrosis, as well as splenomegaly, constitutional symptoms, ineffective erythropoiesis, extramedullary hematopoiesis, and a risk of leukemic progression and shortened survival. Therapy can range from observation alone in lower-risk and asymptomatic patients to allogeneic hematopoietic stem cell transplantation, which is the only potentially curative treatment capable of prolonging survival, although burdened by significant morbidity and mortality. The discovery of the JAK2 V617F mutation prompted the development of JAK inhibitors (JAKi) including the first-in-class JAK1/JAK2 inhibitor ruxolitinib and subsequent approval of fedratinib, pacritinib, and momelotinib. The latter has shown erythropoietic benefits by suppressing hepcidin expression via activin A receptor type 1 (ACVR1) inhibition, as well as reducing splenomegaly and symptoms. However, the current JAKi behave as anti-inflammatory drugs without a major impact on survival or disease progression. A better understanding of the genetics, mechanisms of fibrosis, cytopenia, and the role of inflammatory cytokines has led to the development of numerous therapeutic agents that target epigenetic regulation, signaling, telomerase, cell cycle, and apoptosis, nuclear export, and pro-fibrotic cytokines. Selective JAK2 V617F inhibitors and targeting of mutant CALR by immunotherapy are the most intriguing and promising approaches. This review focuses on approved and experimental treatments for MF, highlighting their biological background.

Clonal hematopoiesis (CH) arises when a substantial proportion of mature blood cells is derived from a single hematopoietic stem cell lineage. It is considered to be a premalignant state that predisposes individuals to an increased risk of cancers. Recently, emerging evidence has demonstrated a strong association between CH and both the incidence and mortality of cardiovascular diseases (CVD), with the relative risks being comparable to those attributed to traditional cardiovascular risk factors. In addition, CH has been suggested to play a role in CVD and anti-cancer treatment-related cardiotoxicity amongst cancer survivors. Moreover, certain forms of chemotherapy and radiation therapy have been shown to promote the clonal expansion of specific CH-related mutations. Consequently, CH may play a substantial role in the realm of cardio-oncology. In this review, we discuss the association between CH with cancer and CVD, with a special focus on anti-cancer treatment-related cardiotoxicity, discuss possible future research avenues and propose a systematic approach for clinical practice.

Calreticulin (CALR) is an endoplasmic reticulum chaperone. Frameshift mutations in CALR were discovered in patients with myeloproliferative neoplasm showing increased platelet counts. The frameshift was observed in the last exon of CALR, leading to a novel C-terminal tail. Calreticulin mutations were categorised into Type I and Type II depending upon the extent of retention of CALR WT sequences. Clinically, Type I mutations induced myelofibrosis, while Type II mutations were associated with early onset of the disease. Both mutations induced ligand-independent activation of the thrombopoietin receptor (TpoR) and consequently enhanced platelet production. However, no specific difference in signalling mechanism could be demonstrated between them. Using over-expression of CALR WT, CALR ∆52 (Type I) and CALR ins5 (Type II) in HEK cells, we showed that Type I CALR mutations downregulated the basal mTORC2 signalling without affecting mTORC1. The decrease in basal mTORC2 signalling was attributed to CALR ∆52-induced increased expression of c-JUN through occupation of the enhancer sequences of jun. Furthermore, increased c-JUN expression decreased the expression of RICTOR, a component of mTORC2. Strikingly, overexpression of RICTOR or knockdown of c-JUN reversed the inhibitory effect of CALR ∆52 on mTORC2 activity. Finally, we demonstrated that CALR ∆52 decreased the glucose uptake and cellular ATP levels in a c-JUN-mTORC2-dependent manner. These findings not only contribute to our understanding of the molecular mechanisms underlying mutant CALR driven myeloproliferative neoplasm but also provide potential therapeutic targets against the disease.

Myelofibrosis (MF) is the most common complication of myeloproliferative neoplasms (MPNs)，which is markedly correlated with a dismal prognosis. Murine model such as the thrombopoietin receptor (MPL)W515L-mutant MPN mouse model functions as a crucial vehicle in disease research, is widely used in basic and applied research on MPNs and MF.However, the lack of methods for dynamic observation of MF progression hinders mechanistic studies and drug development for MF. Here we develop a sensitive, stable and minimally invasive MPN evaluation system to assess the evolution of myelofibrosis in murine model.Key peripheral blood parameters (WBC, RBC, HGB, HCT, PLT, and tumor cell proportion) from MPN mice were analyzed using PCA to reduce dimensionality and generate a comprehensive evaluation score (Y). Based on peripheral blood smear observations and predefined score cut-off values (0.59 and - 0.44), MPN was classified into mild, moderate, and severe stages. Validation conducted across diverse experimental settings yielded outcomes that were in alignment with the pathological grading of myelofibrosis. This system facilitated the dynamic monitoring of MF progression in applied research on pigment epithelium-derived factor treatment for MPN and basic studies on the role of NLRP inflammasomes in the bone marrow microenvironment. We believed that this minimally invasive evaluation system for grading MF severity in MPN mouse model will provide a potential tool for MPN pathogenesis research and targeted therapy development.

Primary myelofibrosis (PMF) is a clonal blood disorder characterized by mutually exclusive driver mutations in JAK2, CALR, or MPL genes. So far, it is largely unclear if the driver mutations have a specific impact on DNA methylation (DNAm) profiles and how epigenetic alterations in PMF are related to other myeloid malignancies.

When we compared DNAm profiles from PMF patients we found very similar epigenetic modifications in JAK2 and CALR mutated cases, whereas MPL mutations displayed less pronounced and distinct patterns. Furthermore, induced pluripotent stem cell (iPSC) models with JAK2 mutations indicated only a moderate association with PMF-related epigenetic changes, suggesting that these alterations may not be directly driven by the mutations themselves. Additionally, PMF-associated epigenetic changes showed minimal correlation with allele burden and seemed to be largely influenced by shifts in the cellular composition. PMF DNAm profiles compared with those from other myeloid malignancies-such as acute myeloid leukemia, juvenile myelomonocytic leukemia, and myelodysplastic syndrome-showed numerous overlapping changes, making it difficult to distinguish PMF based on individual CpGs. However, a PMF score created by combining five CpGs was able to discern PMF from other diseases.

These findings demonstrate that PMF driver mutations do not directly evoke epigenetic changes. While PMF shares epigenetic alterations with other myeloid malignancies, DNA methylation patterns can distinguish between PMF and related diseases.

Arterial and venous thromboses are the most significant complications in patients with myeloproliferative neoplasms (MPNs), with the primary treatment goal being thrombotic risk reduction. In MPN with no history of thrombosis, primary prevention mainly involves the use of aspirin, and cytoreduction is added in high-risk patients. However, thrombotic complications can unveil an MPN in ∼20% of cases, necessitating the initiation of both antithrombotic therapy for the thrombosis and cytoreductive treatment for the MPN. The duration of anticoagulant therapy after an initial venous thromboembolic event is subject to discussion. Furthermore, the occurrence of a thrombotic complication in patients with a known diagnosis of MPN prompts a reconsideration of both antithrombotic and hematologic management. This review uses case-based discussions to explore the management of thrombotic complications in patients with MPN. It addresses the nature and duration of antithrombotic treatments, as well as the approach to cytoreduction. Special attention is given to the place of direct oral anticoagulants and to the management of patients with MPN with splanchnic vein thrombosis, which is disproportionately common in this group.

Somatic mutations in the JAK2, CALR, and MPL genes are traditionally tested using a cascading reflex algorithm in BCR::ABL1-negative myeloproliferative neoplasms (MPNs). However, next-generation sequencing (NGS) has revealed that these variants may coexist, exposing limitations in current testing practices.

This pilot study analyzed 3 JAK2 p.V617F-positive MPN cases and 3 cases negative for classical driver mutations using the Oncomine Myeloid Assay GX v2 assay (Thermo Fisher Scientific) on the Genexus Integrated Sequencer (Thermo Fisher Scientific).

JAK2 p.V617F status was 100% concordant between polymerase chain reaction (PCR) and NGS. Next-generation sequencing detected a concurrent driver MPL mutation in 1 case, an SF3B1 variant in 1 case, and an IDH2 variant in a JAK2-positive case that have established prognostic and therapeutic significance. In cases negative for conventional targets, NGS detected DNMT3A and TET2 variants, which are associated with clonal hematopoiesis and MPN initiation. One case had a JAK2 p.V617F alteration at a variant allele frequency of 0.9%, below the NGS-reportable range but detectable by PCR, adding another caveat to profiling of MPNs.

Next-generation sequencing provides comprehensive molecular profiling in patients with MPNs, identifying additional prognostic and therapeutic markers. However, PCR remains superior for detecting low-variant allele frequency variants. We propose an updated MPN testing strategy that integrates PCR and NGS within a reflex algorithm to optimize diagnostics and therapeutic guidance.

This study aims to conduct a comprehensive bibliometric analysis of ET research, focusing on contributions from authors, institutions, and countries or regions, while mapping collaboration networks. Furthermore, it identifies development trends to provide insights for future research.

A bibliometric analysis of ET-related publications (2001-2024) was conducted using data from the Web of Science Core Collection, focusing on publication trends, co-authorship networks, co-citation relationships, and citation bursts.

A total of 4,297 studies published in 778 journals were included in the analysis. ET research has grown rapidly, with major contributions from researchers in the United States and Europe, particularly through extensive collaborations. Leading figures such as Ayalew Tefferi and Alessandro M. Vannucchi have driven advances in ET classification, molecular mechanisms, and targeted therapies. The discovery of driver mutations, such as JAK2, has revolutionized the diagnostic and therapeutic approaches to ET. Research focus has shifted from clinical morphological diagnosis to molecular diagnostics, with the field now entering the era of targeted therapies. However, the heterogeneity of ET, the limitations of targeted therapies, particularly the lack of management experience and data for high-risk and special populations, as well as the incomplete understanding of the role of inflammation in the disease mechanism, continue to hinder both clinical and scientific progress in ET research.

Bibliometric analysis demonstrates significant advances in ET research, particularly in molecular pathology and targeted therapies. Future research should address ET heterogeneity, optimize management of high-risk and special populations, overcome the limitations of targeted therapies, and further elucidate the role of inflammation to achieve individualized precision therapy.

The classical BCR::ABL-negative myeloproliferative neoplasms (MPN) include polycythemia vera, essential thrombocythemia, and primary myelofibrosis. They are acquired clonal disorders of hematopoietic stem cells leading to hyperplasia of one or several myeloid lineages. MPN are caused by three main recurrent mutations, JAK2V617F and mutations in the calreticulin (CALR) and thrombopoietin receptor (MPL) genes. Here, we review the general diagnosis, the complications, and the management of MPN. Second, we explain the physiopathology of the natural disease development and its regulation, which contributes to MPN heterogeneity. Thirdly, we describe the new paradigm of MPN development highlighting the early origin of driver mutations, decades before the onset of symptoms, and the consequence of early detection of MPN cases in the general population for prompt diagnosis and better medical management. Finally, we present interferon-α therapy as a potential, early disease-modifying drug after reporting its good hematologic and molecular efficacies in polycythemia vera, essential thrombocythemia, and early myelofibrosis in clinical trials as well as its mechanism of action in pre-clinical studies. As a result, we may expect that, in the future, MPN patients will be diagnosed very early during the course of disease and that new selective therapies under development, such as interferon-α, JAK2V617F inhibitors and CALRmut monoclonal antibodies, will be able to intercept the mutated clones.

Allogeneic hematopoietic cell transplantation (HCT) is the only curative treatment for myelofibrosis (MF), and current guidelines recommend assessing all patients with MF for eligibility. Several patient- and disease-specific factors impact transplantation outcomes, and timely assessment of potential transplant candidates is key to optimizing post-HCT outcomes. The role of HCT in the treatment of MF continues to evolve, with the adoption of newer and safer approaches, enhanced donor availability, use of reduced-intensity conditioning, improvements in graft-versus-host disease (GVHD) prophylaxis and treatment, and greater understanding of high-risk clinical and molecular features of the disease. These developments highlight the importance of early and ongoing assessment throughout the MF disease course to optimize eligibility and consideration for HCT. Ruxolitinib is approved for first-line treatment of intermediate- or high-risk MF, and emerging data have clarified the important role of ruxolitinib in not only optimizing clinical status before HCT but also mitigating and treating post-HCT complications in patients with MF, notably acute and chronic GVHD and relapse. Here we review strategies for optimizing clinical outcomes in patients considered for and undergoing HCT for MF treated with ruxolitinib. We discuss strategies for appropriate patient and donor selection, optimization of ruxolitinib therapy in the pre- and peri-HCT periods, choice of conditioning regimen, GVHD prophylaxis, post-HCT management of GVHD, continued monitoring for MF relapse, and the role of post-HCT ruxolitinib maintenance to reduce risks of GVHD and disease relapse.

Myelofibrosis (MF) is a chronic myeloid neoplasm characterized by myeloproliferation, bone marrow fibrosis, splenomegaly, and constitutional symptoms related to pro-inflammatory cytokine signaling. Biologically, MF is characterized by constitutive activation of JAK-STAT signaling; accordingly, JAK inhibitors have been rationally developed to treat MF. Following the initial approval of ruxolitinib in 2011, three additional agents have been approved: fedratinib, pacritinib, and momelotinib. As these therapies are noncurative, allogeneic stem cell transplantation remains a key treatment modality and patients with MF who are deemed candidates should be referred to a transplant center. This potentially curative but toxic approach is typically reserved for patients with higher-risk disease, and JAK inhibitors are recommended in the pretransplant setting. JAK inhibitors have proven effective at managing splenomegaly and constitutional symptoms and should be started early in the disease course in patients presenting with these clinical manifestations; asymptomatic patients may initially be followed with close surveillance. Drug-related myelosuppression has been a challenge with initial JAK inhibitors, particularly in patients presenting with a cytopenic phenotype. However, newer agents, namely pacritinib and momelotinib, have proven more effective in this setting and are approved for patients with significant thrombocytopenia and anemia, respectively. Resistance or disease progression is clinically challenging and may be defined by several possible events, such as increasing splenomegaly or progression to accelerated or blast phase disease. However, with multiple JAK inhibitors now approved, sequencing of these agents appears poised to improve outcomes. Additionally, novel JAK inhibitors and JAK inhibitor-based combinations are in clinical development.

Patients with essential thrombocythemia (ET) have a chronic evolution with a risk of hematologic transformation associated with a dismal outcome. Because patients with resistance or intolerance have adverse prognosis, it is important to identify which patient will respond to first-line treatment. We, therefore, aim to describe the association between additional mutations and response to first-line treatment in patients with ET. In this retrospective study, we analyzed the molecular landscape of 121 ET patients first-line treated with hydroxyurea (HU; n = 86) or pegylated interferon (peg-IFN; n = 35). Patients undergoing peg-IFN therapy were younger and had higher proportion of low and very low risk of thrombosis recurrence. A total of 62 patients (51%) had ≥1 additional mutations at diagnosis. At 12 months of treatment, 75 patients (62%) achieved complete response (CR), 37 (31%) partial response, and 7 (6%) no response. The presence of at least 1 additional mutation at diagnosis was associated with not achieving CR (hazard ratio [HR], 0.65; P = .038), whereas treatment with peg-IFN was associated with higher CR (HR, 2.00; P = .002). The number of additional mutations at diagnosis was associated with hematologic progressions (P < .0001). None of the patients receiving peg-IFN therapy progressed to myelofibrosis, whereas 16 of 86 patients (19%) treated with HU developed secondary myelofibrosis. In conclusion, our results suggest that the presence of at least 1 additional mutation at diagnosis is associated with failure to achieve CR and also with an increased risk of hematologic evolution.

Despite its known superior diagnostic yield for chromosomal anomalies compared with karyotype and fluorescence in situ hybridization (FISH) studies, chromosome genomic array testing (CGAT) is not used as a routine clinical test for myelofibrosis. Although many prognostic systems exist that risk stratify patients at diagnosis, limited tools are available to prognosticate transplant outcome.

The current study aimed at testing whether CGAT results obtained before transplantation improves prognosis of post-transplant outcome in patients with myelofibrosis compared with current risk categorization systems, for example, DIPSS plus (Dynamic International Prognostic Scoring System).

We studied patients with myelofibrosis who underwent hematopoietic cell transplantation between 2000 and 2017 at our center (N = 44). We assessed the prognostic significance of CGAT, DIPSS plus, and the total count of gene mutations for post-transplant clinical outcomes, including relapse-free survival (RFS), overall survival (OS), and graft-versus-host-disease (GVHD).

Abnormal CGAT results were seen in 24 patients (55%), including 18 with copy-neutral loss of heterozygosity (cnLOH, 41%). With a median follow-up of 91 (range 2-258) months starting from the CGAT sample date, RFS was 59% and OS was 68%. The outcome analysis showed significant prognostic implication from CGAT (normal vs. abnormal), specifically for patients with intermediate risk by DIPSS-plus scores and those with 0∼2 mutations. CGAT alone significantly stratified the patients' RFS outcome (P = .03). The addition of CGAT to DIPSS-plus improved the significance from a P value of .08 to .003, whereas the addition of CGAT to mutation count improved the P value from .02 to .01. The best stratification system for RFS was achieved when CGAT, DIPSS-plus, and mutation count were all considered (P = 1e-08). The current study also confirmed individual anomalies that are prognostically significant, including U2AF1 mutation (n = 5, P = .03) and 1q gain (n = 3, P = .01), which were associated with worse RFS. ASXL1 mutations (n = 14) appeared to associate with a later onset of chronic GVHD (P =.03).

Pretransplant CGAT analysis augments the existing risk stratification tools and may be considered as routine clinical testing for myelofibrosis.

Patients with chronic, indolent myeloproliferative neoplasms (MPNs) are at risk for transformation to highly lethal leukemia, although targetable mechanisms driving progression remain elusive. We discovered that the High Mobility Group A1 (HMGA1) gene is up-regulated with MPN progression in patients and required for evolution into myelofibrosis (MF) or acute myeloid leukemia (AML) in preclinical models. HMGA1 encodes the HMGA1 epigenetic regulators that modulate the chromatin state during embryogenesis and tissue regeneration. While HMGA1 is silenced in most differentiated cells, it becomes aberrantly re-expressed in JAK2 mutant (JAK2-V617F) MPN, with the highest levels after transformation to secondary MF or AML. Here, we review recent work highlighting HMGA1 function in MPN progression. Though underlying mechanisms continue to emerge, increasing evidence suggests that HMGA1 functions as a "chromatin key" required to "unlock" regions of the genome involved in clonal expansion and progression in MPN. Together, these findings illuminate HMGA1 as a driver of MPN progression and a promising therapeutic target.

Essential thrombocythemia, a clonal myeloproliferative neoplasm with excessive platelet production, is associated with an increased risk of thrombosis and bleeding. The annual incidence rate of essential thrombocythemia in the US is 1.5/100 000 persons.

Patients with essential thrombocythemia have a persistent platelet count of 450 × 109/L or greater. The differential diagnosis includes myeloproliferative neoplasms (polycythemia vera, primary myelofibrosis, chronic myeloid leukemia); inflammatory conditions such as rheumatoid arthritis and systemic lupus erythematosus; infections; splenectomy; iron deficiency anemia; and solid tumors such as lung cancer. Approximately 90% of individuals with essential thrombocythemia have genetic variants that upregulate the JAK-STAT (signal transducer and activator of transcription 5) signaling pathway, including Janus kinase 2 (JAK2, 64%), calreticulin (CALR, 23%), and myeloproliferative leukemia virus oncogene (MPL, 4%). The median age at diagnosis of essential thrombocythemia is 59 years. The median overall survival exceeds 35 years in those diagnosed at 40 years or younger. Patients with essential thrombocythemia are at increased risk of arterial thrombosis (11%), venous thrombosis (7%), and hemorrhagic complications (8%). Thrombosis risk is increased among those with a history of thrombosis, age older than 60 years, a JAK2 gene variant, and cardiovascular risk factors (eg, hypertension, diabetes mellitus, hyperlipidemias, tobacco use). Use of aspirin (81-100 mg/d) is suggested for most patients with essential thrombocythemia to lower thrombosis risk. In a retrospective study of 300 affected patients with a low thrombosis risk (younger than 60 years with no prior thrombosis), those not taking aspirin (100 mg/d) had a risk of arterial thrombosis of 9.4/1000 patient-years and a venous thrombosis risk of 8.2/1000 patient years; cardiovascular risk factors were associated with a higher risk of arterial thrombi (incidence rate ratio, 2.5 [95% CI, 1.02-6.1]), and a JAK2 gene variant was associated with increased risk of venous thrombosis (incidence rate ratio, 4.0 [95% CI, 1.2-12.9]). In a randomized trial of 114 patients at higher risk for thrombosis (age older than 60 years or a prior thrombotic event), cytoreduction with hydroxyurea significantly lowered the risk of arterial or venous thrombotic events compared with no cytoreductive therapy (3.6% vs 24%; P < .01). At a median of 8.5 years from diagnosis, approximately 10% of patients with essential thrombocythemia develop myelofibrosis and about 3% develop acute myeloid leukemia.

Essential thrombocythemia is a rare clonal myeloproliferative neoplasm associated with an increased risk of venous and arterial thrombosis, hemorrhage, myelofibrosis, and acute myeloid leukemia. Based on individual risk factors for thrombosis, persons with essential thrombocythemia may be treated with low-dose aspirin, either alone or in combination with a cytoreductive drug such as hydroxyurea.

Calreticulin (CRT) is a 46 kDa highly conserved protein initially identified as calregulin, a prominent Ca2+-binding protein of the endoplasmic reticulum (ER). Subsequent studies have established that CRT functions in the ER's protein folding response and Ca2+ homeostatic mechanisms. An ER retention signal on the carboxyl terminus of CRT suggested that CRT was restricted to the ER. However, the identification of CRT in the nucleus and cytosol has established that CRT is a multi-compartmental, multifunctional protein. CRT also plays an important role in cancer progression. Most recently, CRT was identified on the cell surface and shown to be a potent 'eat-me' signal that plays a key role in the uptake of apoptotic and viable cancer cells by phagocytes. Elevated CRT exposure on the outer leaflet of cancer cells has been linked with anticancer immunity and superior therapeutic outcomes in patients with non-small cell lung carcinoma, colorectal carcinoma, acute myeloid leukemia, ovarian cancer, and high-grade serous carcinomas. Mutations in the CRT gene have been identified in a subset of patients with myeloproliferative neoplasms. The most recent studies from our laboratory have revealed a new and significant function for extracellular CRT as a plasminogen receptor. This discovery has profound implications for our understanding of the role of CRT in myeloproliferative neoplasms, specifically, essential thrombocythemia.

Aurora kinase B (AURKB) was reported to assist Aurora kinase A (AURKA) to regulate cellular mitosis. AURKA has been found activated in myeloproliferative neoplasms (MPNs) patients with CALR gene mutation, however, it's unclear whether AURKB displays a compensatory function of AURKA in regulation of CALR mutant cell growth and differentiation. Here, we found that AURKB, similar with AURKA, was aberrantly activated in CALR mutant patients, and displayed a more tolerance to the aurora kinase inhibitor. Inhibition of AURKA decreased cell growth and colony formation, induced cell differentiation and apoptosis, while, this inhibitive degree was further enhanced when AURKB was blocked by incremental inhibitor. Transcriptomic analyses revealed a more significant gene enrichment in cells with knockdown of AURKB than that of AURKA, mainly reflecting in oxidative phosphorylation, mitosis, proliferation and apoptosis signaling pathway. Moreover, downregulation of AURKB enhanced cell growth arrest and apoptosis more obviously than that of AURKA, and additionally promoted cell differentiation and metabolism-oxygen consumption rate (OCR). Otherwise, overexpression of AURKA or AURKB facilitated the cell proliferation of CALR mutant cells, and made cells more sensitive to the aurora kinase inhibitor. These results suggest that activated AURKB not only supports the functions of AURKA in promoting the growth of CALR mutated cells, but also has impeded the differentiation of these cells.

More than a decade following the discovery of Calreticulin (CALR) mutations as drivers of myeloproliferative neoplasms (MPN), advances in the understanding of CALR-mutant MPN continue to emerge. Here, we summarize recent advances in mehanistic understanding and in targeted therapies for CALR-mutant MPN.

Structural insights revealed that the mutant CALR-MPL complex is a tetramer and the mutant CALR C-terminus is exposed on the cell surface. Targeting mutant CALR utilizing antibodies is the leading therapeutic approach, while mutant CALR-directed vaccines are also in early clinical trials. Additionally, chimeric antigen receptor (CAR) T-cells directed against mutant CALR are under evaluation in preclinical models. Approaches addressing the cellular effects of mutant CALR beyond MPL-JAK-STAT activation, such as targeting the unfolded protein response, proteasome, and N-glycosylation pathways, have been tested in preclinical models. In CALR-mutant MPN, the path from discovery to mechanistic understanding to direct therapeutic targeting has advanced rapidly. The longer-term goal remains clonally-selective therapies that modify the disease course in patients.

Myeloid neoplasms include myeloproliferative and myelodysplastic neoplasms and acute myeloid leukaemia. Historically, these diseases have been diagnosed based on clinicopathological features with sometimes arbitrary thresholds that have persisted even as molecular features were gradually incorporated into their classification. As such, although current diagnostic approaches can classify the majority of myeloid neoplasms accurately using a combination of molecular and clinicopathological features, some areas of overlap persist and occasionally pose diagnostic challenges. These include overlap across BCR::ABL1-negative myeloproliferative neoplasms; between clonal cytopenia of undetermined significance and myelodysplastic neoplasms; myelodysplastic/myeloproliferative neoplasms; and, detection of KIT mutations in myeloid neoplasms other than mastocytosis, raising the prospect of systemic mastocytosis. Molecular testing has become state of the art in the diagnostic work-up of myeloid neoplasms, and molecular patterns can inherently help to classify overlapping entities if considered within a framework of haematological presentations. For future development, molecular testing will likely include whole genome and transcriptome sequencing, and primarily molecular classifications of myeloid neoplasms have already been suggested. As such, genetically defined groups should still constitute the basis for our understanding of disease development from early onset to progression, while clinicopathological features could then be used to describe the stage of the disease rather than the specific type of myeloid neoplasm.

Calreticulin (CALR) mutations are detected in around 20% of patients with primary and post-essential thrombocythemia myelofibrosis (MF). Regardless of driver mutations, patients with splenomegaly and symptoms are generally treated with JAK2-inhibitors, most commonly ruxolitinib. Recently, new therapies specifically targeting the CALR mutant clone have entered clinical investigation. To collect information on efficacy and safety of ruxolitinib in CALR-mutated patients, we report a sub-analysis of the "RUX-MF" (NCT06516406) study, comprising 135 CALR-mutated and 786 JAK2-mutated ruxolitinib-treated patients. Compared to JAK2-mutated patients, CALR-mutated patients started ruxolitinib with a more severe disease (higher peripheral blast counts, lower hemoglobin levels and worse marrow fibrosis) and after a longer median time from diagnosis (2.6 versus 0.7 years, p < 0.001). At 6 months, spleen responses were numerically inferior in CALR-mutated patients, who also had significantly lower rates of symptom responses (56.1% versus 66.7%, p = 0.04).

To compare the efficacy and safety of gecacitinib (also known as jaktinib) with hydroxyurea (HU) in treating myelofibrosis (MF) patients. In this multicenter, randomized phase 3 trial (ZGJAK016), intermediate- or high-risk primarily JAK inhibitor naïve MF patients were assigned in a 2:1 ratio to receive either gecacitinib (100 mg twice a day, BID) or HU (500 mg BID). The primary endpoint was the proportion of patients with ≥35% reduction in spleen volume (SVR35) from baseline at week 24. Secondary endpoints included the best spleen response rate, the proportion of patients with a ≥50% reduction in total symptom score (TSS50), anemia improvement, and safety profile. At 24 weeks, the SVR35 was reached by 64.8% of patients on gecacitinib (46/71), compared to 26.5% on HU (9/34), P = 0.0002. The best spleen response rates were also superior for gecacitinib at 81.7%, vs 32.4% for HU, P < 0.0001. The TSS50 rates were 62.0% for gecacitinib- and 50% for HU-treated patients. Among non-transfusion-dependent patients with baseline hemoglobin (HGB) ≤ 100 g/L, 31.0% (13/42) in the gecacitinib group showed a ≥20 g/L increase in HGB, compared to 15.0% (3/20) in HU group. The common grade ≥ 3 treatment-emergent adverse events (TEAEs), including anemia (26.8% vs 44.1%), thrombocytopenia (15.5% vs 32.4%), leukopenia (2.8% vs 20.6%), and neutropenia (1.4% vs 20.6%), were less frequent with gecacitinib than HU. Treatment discontinuation due to TEAEs was lower in gecacitinib (7.0%) compared to HU (11.8%). Gecacitinib demonstrates superior efficacy and a more favorable safety profile compared to HU, making it a promising treatment option for managing MF, particularly in patients with anemia (This trial was registered with ClinicalTrials.gov, (NCT04617028)).

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic cancers characterized by hyperproliferation of the myeloid lineages. These clonal marrow disorders are extremely rare in pediatric patients. MPN is reported to occur 100 times more frequently in adults, and thus research is primarily focused on this patient group. At present, modern diagnostic techniques, primarily genetic, facilitate the identification of the biology of these diseases. The key genes are JAK2, MPL, and CALR, namely, driver mutations, which are present in approximately 90% of patients with suspected MPN. Moreover, there are more than 20 other mutations that affect the development of these hematological malignancies, as evidenced by a review of the literature. The pathogenic mechanism of MPNs is characterized by the dysregulation of the JAK/STAT signaling pathway (JAK2, MPL, CALR), DNA methylation (TET2, DNMT3A, IDH1/2), chromatin structure (ASXL1, EZH2), and splicing (SF3B1, U2AF2, SRSF2). Although rare, myeloproliferative neoplasms can involve young patients and pose unique challenges for clinicians in diagnosis and therapy. The paper aims to review the biological markers of MPNs in pediatric populations-a particular group of patients that has been poorly studied due to the low frequency of MPN diagnosis.

Constitutive activation of Janus kinase 2 (JAK2)/signal transducer and activator of transcription (STAT) signaling pathway is central to the pathogenesis of myeloproliferative neoplasms (MPNs). Long noncoding RNAs (lncRNAs) regulate diverse biological processes. However, the role of lncRNAs in MPN pathogenesis is not well studied.

The expression of lnc-AC004893 in MPN patients was measured by quantitative real-time PCR (qRT-PCR). Gene-specific short hairpin RNAs (shRNAs) were designed to inhibit the expression of lnc-AC004893, and western blot was performed to explore the role of lnc-AC004893 via regulating the JAK2/STAT5 signaling pathway. Furthermore, co-IP was performed to determine the binding ability of lnc-AC004893 and STAT5 protein. Finally, the BaF3-JAK2V617F-transplanted mouse model was used to assess the biological role of lnc-ac004893 in vivo.

We report that lnc-AC004893, a poorly conserved pseudogene-209, is substantially upregulated in MPN cells compared with normal controls (NCs). Knockdown of lnc-AC004893 by specific shRNAs suppressed cell proliferation and decreased colony formation. Furthermore, the knockdown of lnc-AC004893 reduced the expression of p-STAT5 but not total STAT5 in HEL and murine IL-3-dependent Ba/F3 cells, which present constitutive and inducible activation of JAK2/STAT5 signaling. In addition, inhibition of murine lnc-ac004893 attenuated BaF3-JAK2V617F-transplanted phenotypes and extended the overall survival. Mechanistically, knockdown of lnc-AC004893 enhanced the binding ability of STAT5 and protein tyrosine phosphatase SHP1. Furthermore, knockdown of lnc-AC004893 decreased STAT5-lnc-AC004893 interaction but not SHP1-lnc-AC004893 interaction.

Lnc-AC004893 regulates STAT5 phosphorylation by affecting the interaction of STAT5 and SHP1. Lnc-AC004893 might be a potential therapeutic target for MPN patients.

Primary myelofibrosis (PMF) is the most advanced subtype among the classic Philadelphia chromosomenegative myeloproliferative neoplasms (MPNs). A majority of patients carry one of three mutually-exclusive somatic driver mutations: JAK2 (60-65%), CALR (20-25%), or MPL (5%). Co-occurrence of these mutations is rarely reported. Here we report a case with a triple positive combination of JAK2, CALR and MPL driver mutations.

A 69-year-old male was admitted to hospital for acute exacerbation of chronic obstructive pulmonary disease (COPD) and was found to have splenomegaly and leukocytosis. Nextgeneration revealed JAK2, CALR, MPL mutations, and additional variants in SF3B1, SRSF2, and STAG2. The patient was diagnosed with PMF and treated with ruxolitinib and COPD therapy. Due to nausea, the ruxolitinib dose was reduced. After therapy, spleen volume decreased and hematologic responses were poor. Another genetic mutation of ASXL1 was later found. After adjusting the medication and adding antiemetics, the patient's condition improved.

The rare coexistence of JAK2, CALR, and MPL mutations challenges the assumption of their mutual exclusivity. Further study of these mutations is essential for developing better treatment strategies.

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm characterized by bone marrow fibrosis, cytopenias, and organomegaly. Four JAK inhibitors are US-FDA approved for treatment of MF. While these drugs reduce symptom burden and spleen size to varying degrees, they do not affect the natural disease course or decrease the risk of leukemic transformation. Therefore, there is a strong need for newer therapies to further advance the field and improve the outcomes of MF. In this review, we cover novel therapies for MF currently in early stages of development.

We present the latest data from early phase clinical trials in MF using drugs with diverse therapeutic mechanisms, including novel JAK-STAT pathway inhibitors, epigenetic therapies, antifibrotic agents, and immunotherapeutic strategies. Additionally, we cover drugs targeted toward anemia improvement in MF.

Numerous agents representing diverse drug classes are in clinical development for MF. While deeper and durable improvements in splenomegaly, symptoms, and anemia are the main clinical objectives, a number of putative biomarkers are being assessed as measures of potential 'disease modification.' Although JAK inhibitor monotherapy represents the current standard, it is hoped that JAK inhibitor-based rational combinations and driver mutation-specific therapies will soon usher in a new era.

This study aimed to compile bioinformatic and experimental information for JAK2 missense variants previously reported in myeloproliferative neoplasms (MPN) and determine if germline JAK2-I724T, recently found to be common in New Zealand Polynesians, associates with MPN.

For all JAK2 variants found in the literature, gnomAD_exome allele frequencies were extracted and REVEL scores were calculated using the dbNSFP database. We investigated the prevalence of JAK2-I724T in a cohort of 111 New Zealand MPN patients using a TaqMan assay, examined its allelic co-occurrence with JAK2-V617F using Oxford Nanopore sequencing, and modelled the impact of I724T on JAK2 using I-Mutant and ChimeraX software.

Several non-V617F JAK2 variants previously reported in MPN had REVEL scores greater than 0.5, suggesting pathogenicity. JAK2-I724T (REVEL score 0.753) was more common in New Zealand Polynesian MPN patients (n = 2/27; 7.4%) than in other New Zealand patients (n = 0/84; 0%) but less common than expected for healthy Polynesians (n = 56/377; 14.9%). Patients carrying I724T (n = 2), one with polycythaemia vera and one with essential thrombocythaemia, had high-risk MPN. Both patients with JAK2-I724T were also positive for JAK2-V617F, found on the same allele as I724T, as well as separately. In silico modelling did not identify noticeable structural changes that would give JAK2-I724T a gain-of-function.

Several non-canonical JAK2 variants with high REVEL scores have been reported in MPN, highlighting the need to further understand their relationship with disease. The JAK2-I724T variant does not drive MPN, but additional investigations are required to exclude any potential modulatory effect on the MPN phenotype.

Cytokines are pleiotropic molecules involved in hematopoiesis, immune responses, infections, and inflammation. They play critical roles in hematopoietic cell transplantation (HCT) and immune effector cell (IEC) therapies, mediating both therapeutic and adverse effects. Thus, cytokines contribute to the immunopathology of graft-versus-host disease (GVHD), cytokine release syndrome (CRS), and immune effector cell-associated neurotoxicity syndrome (ICANS). This review examines cytokine functions in these contexts, their influence on engraftment and immune recovery post-transplantation, and their role in mediating toxicities. We focus on current and potential uses of cytokines to enhance engraftment and potentiate IEC therapies, as well as strategies to mitigate cytokine-mediated complications using cytokine blockers (e.g., tocilizumab, anakinra) and JAK inhibitors (e.g., ruxolitinib). We discuss new insights into GVHD physiology that have led to novel treatments, such as CSF1R blockade, which is effective in refractory chronic GVHD.

Myeloproliferative neoplasms (MPNs) are hematological disorders characterized by abnormal production of myeloid cells due to genetic mutations. Since 2013, researchers have identified somatic mutations in the Calreticulin (CALR) gene, primarily insertions or deletions, in two Philadelphia chromosome-negative MPNs; essential thrombocytosis (ET) and primary myelofibrosis (PMF), and occasionally in chronic myelomonocytic leukemia (CMML). This study aims to identify the various types of CALR mutations and their impact on CALR-positive MPN patients' clinical manifestations and outcomes.

A single-center retrospective study was conducted. The data was collected from pre-existing records. The study was carried out on Philadelphia-negative MPN patients who were being followed up on at the NCCCR (National Center for Cancer Care and Research) to assess the clinical manifestation and outcome of disease treatment. All patients included, were followed in our center between January 1, 2008, and November 20, 2021.

A total of 50 patients with CALR-positive MPN were reviewed with a median follow-up of three years (1-11). This cohort included 31 (62%) patients with ET, 10 (20%) patients with PMF, and 9 (18%) patients with prefibrotic myelofibrosis (pre-MF). The study involved 38 (76%) male and 12 (24%) female patients. There were 16 (32%) patients diagnosed before the age of 40, 24 (48%) patients diagnosed between the ages of 40 and 60; and 10 (20%) patients diagnosed after the age of 60. Molecular analysis showed 24 (48%) patients with CALR type 1, 21 (42%) patients with CALR type 2, and 5 (10%) patients with none Type 1, none Type 2 CALR mutations. Two patients have double mutations; 1(2%) with none Type 1, none Type 2 CALR and JAK2 mutations, and 1(2%) with CALR type 1 and MPL mutations. The thrombotic events were 3 (6%) venous thromboembolisms, 3 (6%) abdominal veins thromboses, 2 (4%) strokes, and 4 (8%) ischemic cardiac events. Only 4 (8%) patients progressed to Myelofibrosis and were carrying CALR 1 mutations, and 1 (2%) patient progressed to AML with CALR 2 mutation.

The data shows a significant rise in CALR-positive MPN diagnoses in younger people, emphasizing the need for a better assessment tool to improve disease management and reduce complications.

In this issue of Blood, Reis et al1 identify a monoclonal antibody, INCA033989, that selectively targets mutant calreticulin (mutCALR) in myeloproliferative neoplasms (MPNs), inhibiting its oncogenic activity without affecting normal hematopoiesis.

Modern oncology increasingly relies on the role of proteins as key components in cancer diagnosis, prognosis, and targeted therapy. This review examines advancements in protein biomarkers across several cancer types, including breast cancer, lung cancer, ovarian cancer, and hepatocellular carcinoma. These biomarkers have proven critical for early detection, treatment response monitoring, and tailoring personalized therapeutic strategies. The article highlights the utility of targeted therapies, such as tyrosine kinase inhibitors and monoclonal antibodies, in improving treatment efficacy while minimizing systemic toxicity. Despite these advancements, challenges like tumor resistance, variability in protein expression, and diagnostic heterogeneity persist, complicating universal application. The review underscores future directions, including the integration of artificial intelligence, advanced protein analysis technologies, and the development of combination therapies to overcome these barriers and refine personalized cancer treatment.

Myeloproliferative neoplasms (MPN) are a heterogenous group of disorders of clonal hematopoiesis characterized by constitutive activation of the JAK/STAT signaling pathway leading to proliferation of blood cells. Cardiovascular disease (CVD) contributes significantly to the morbidity and mortality of patients with MPN. Particularly well-known CVD complications of MPNs are arterial and venous thrombotic events. However, MPNs are also associated with other forms of CVD including atrial fibrillation, heart failure, and pulmonary hypertension. Recent studies have characterized outcomes of patients with MPN and CVD, including acute myocardial infarction (AMI), heart failure, atrial fibrillation, and pulmonary hypertension. Additionally, optimal cardiovascular disease prevention strategies in patients with MPN are not yet clear. Further investigation is warranted to improve CVD outcomes in patients with MPN. Clinicians should be aware of cardiovascular complications of MPN, including thrombotic as well as non-thrombotic complications (heart failure, arrhythmias, pulmonary hypertension).

Clonal hematopoiesis (CH), the expansion of hematopoietic stem cells and their progeny driven by somatic mutations in leukemia-associated genes, is a common phenomenon that rises in prevalence with advancing age to affect most people older than 70 years. CH remains subclinical in most carriers, but, in a minority, it progresses to a myeloid neoplasm, such as acute myeloid leukemia, myelodysplastic syndrome, or myeloproliferative neoplasm. Over the last decade, advances in our understanding of CH, its molecular landscape, and the risks associated with different driver gene mutations have culminated in recent developments that allow for a more precise estimation of myeloid neoplasia risk in CH carriers. In turn, this is leading to the development of translational and clinical programs to intercept and prevent CH from developing into myeloid neoplasia. Here, we give an overview of the spectrum of CH driver mutations, what is known about their pathophysiology, and how this informs the risk of incident myeloid malignancy.

Recurrent somatic mutations in the JAK2 , CALR , and the MPL genes are noted in BCR:ABL1 negative classic myeloproliferative neoplasms (MPN) that includes polycythemia vera (PV), essential thrombocytosis (ET), and primary myelofibrosis (PMF).

Mutation profile and clinical features of MPN cases diagnosed at a tertiary care center in North India are being described. JAK2V617F mutation was screened using ARMS PCR, and CALR mutation was screened using allele-specific PCR followed by fragment analysis. MPL and JAK2 Exon 12 mutations were screened by Sanger sequencing. Some of the samples were also screened using commercial kits based on single-plex RT PCR.

A total of 378 cases (including 124 PV, 121 ET, and 133 PMF cases) were screened over 6.5 years. JAK2V617F mutation was noted in 90.3%, 61.1%, and 69.2% of cases of PV, ET, and PMF, respectively. In PV, JAK2V617F wild-type cases were associated with a significantly lower age (44 yrs vs 54 yrs; P = 0.001), lower TLC (6.3 vs 16.9; P = 0.001), and a lower platelet count (188 × 109/L vs 435 × 109/L; P = 0.009) as compared to the JAK2V617F mutated cases. CALR and MPL mutations were noted in 17.4% and 12% and 0.8% and 5.3% of ET and PMF cases, respectively. Type 1 CALR mutations were commoner in both ET and PMF. The triple negative cases constituted 20.7% and 13.5% cases of ET and PMF, respectively. In ET, the triple negative cases were found to have a significantly lower median age of presentation (42 yrs vs 52 yrs; P = 0.001), lower median TLC (10.2 × 109/L vs 13.2 × 109/L; P = 0.024), and a higher median platelet count (1238 × 109/L vs 906 × 109/L; P = 0.001) as compared to driver genes mutated cases. In PMF, the triple negative cases were found to have a significantly lower hemoglobin level (7.9 g/dl vs 11.0 gl/dl; P = 0.001) and a significant female preponderance ( P = 0.05) as compared to the mutated cases. CALR mutations were found to have a significantly lower median age (43 yrs vs 56 yrs; P = 0.001) and lower hemoglobin (9.6 g/dl vs 11.3 g/dl) as compared to the JAK2 mutations.

Our data on the driver gene mutational profile of BCR:ABL1 negative MPN is one of the largest patient cohorts. The prevalence and clinicopathological features corroborate with that of other Asian studies.

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.

Dysregulated JAK/STAT hyperactivity is essential to the pathogenesis of myelofibrosis, and JAK inhibitors are the first-line treatment option for many patients. There are four FDA-approved JAK inhibitors for patients with myelofibrosis. Single-agent JAK inhibition can improve splenomegaly, symptom burden, cytopenias, and possibly survival in patients with myelofibrosis. Despite their efficacy, JAK inhibitors produce variable or short-lived responses, in part due to the large network of cooperating signaling pathways and downstream targets of JAK/STAT, which mediates upfront or acquired resistance to JAK inhibitors. Synergistic inhibition of JAK/STAT accessory pathways can increase the rates and duration of response for patients with myelofibrosis. Two recently reported, placebo-controlled phase III trials of novel agents added to JAK inhibition met their primary endpoint, and additional late-stage studies are ongoing. This paper will review role of dysregulated JAK/STAT signaling, biological plausible additional therapeutic targets and the recent advancements in combination strategies with JAK inhibitors for myelofibrosis.

Myeloproliferative neoplasms (MPNs), encompassing disorders like polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are characterized by clonal hematopoiesis without the Philadelphia chromosome. The JAK2 V617F mutation is prevalent in PV, ET, and PMF, while mutations in MPL and CALR also play significant roles. These conditions predispose patients to thrombotic events, with PMF exhibiting the lowest survival among MPNs. Chronic inflammation, driven by cytokine release from aberrant leukocytes and platelets, amplifies cardiovascular risk through various mechanisms, including atherosclerosis and vascular remodeling. Additionally, MPN-related complications like pulmonary hypertension and cardiac fibrosis contribute to cardiovascular morbidity and mortality. This review consolidates recent research on MPNs' cardiovascular implications, emphasizing thrombotic risk, chronic inflammation, and vascular stiffness. Understanding these associations is crucial for developing targeted therapies and improving outcomes in MPN patients.

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are clonal haematopoietic stem cell disorders characterized by specific driver mutations and an increased risk of both macrothrombosis and microthrombosis. Serotonin receptor type 1B (HTR1B) was found to be expressed by various solid tumours, and also primary bone marrow mononuclear cells from myelodysplastic neoplasm and acute myeloid leukaemia patients, representing a potential therapeutic target. In this study we assessed for the first time the expression levels of HTR1B mRNA in the peripheral blood mononuclear cells (PBMC) of 85 newly diagnosed MPN patients, consisting of 28 polycythemia vera, 25 essential thrombocythemia and 32 primary myelofibrosis cases. Levels of HTR1B expression between MPN subtypes and control group were not significantly different. However, at clinical data examination, it was observed that MPN patients with a recent history of major thrombosis and/or signs of impaired microcirculation exhibited significantly higher HTR1B expression levels compared to non-thrombotic MPNs and control group. Moreover, thrombotic MPN patients had significantly higher HTR1B expression than patients with recent thrombosis and absence of MPN diagnostic criteria. These findings suggest that increased levels of HTR1B expression in PBMC might be associated with thrombosis in MPN patients, but larger studies are needed for confirmation, including testing of the receptor protein expression level.

Leukemia represents a diverse group of hematopoietic neoplasms that can be classified into different subtypes based on the molecular aberration in the affected cell population. Identification of these molecular classification is required to identify specific targeted therapeutic approaches for each leukemic subtype. In general, targeted therapy approaches achieve good responses in some leukemia subgroups, however, resistance against these targeted therapies is common. In this review, we summarize molecular drug resistance biomarkers in targeted therapies in BCR::ABL1-driven chronic myeloid leukemia (CML) and JAK2-driven myeloproliferative neoplasms (MPNs). While acquisition of secondary mutations in the BCR::ABL1 kinase domain is the a common mechanism associated with TKI resistance in CML, in JAK2-driven MPNs secondary mutations in JAK2 are rare. Due to high prevalence and lack of specific therapy approaches in MPNs compared to CML, identification of crucial pathways leading to inhibitor persistence in MPN model is utterly important. In this review, we focus on different alternative signaling pathways activated in both, BCR::ABL1-mediated CML and JAK2-mediated MPNs, by combining data from in vitro and in vivo-studies that could be used as potential biomarkers of drug resistance. In a nutshell, some common similarities, especially activation of PDGFR, Ras, PI3K/Akt signaling pathways, have been demonstrated in both leukemias. In addition, induction of the nucleoprotein YBX1 was shown to be involved in TKI-resistant JAK2-mediated MPN, as well as TKI-resistant CML highlighting deubiquitinating enzymes as potential biomarkers of TKI resistance. Taken together, whole exome sequencing of cell-based or patients-derived samples are highly beneficial to define specific resistance markers. Additionally, this might be helpful for the development of novel diagnostic tools, e.g., liquid biopsy, and novel therapeutic agents, which could be used to overcome TKI resistance in molecularly distinct leukemia subtypes.