How I treat polycythemia vera

Management of hematocrit levels for testosterone replacement patients, a narrative review

INTRODUCTION

Testosterone replacement therapy is gaining more and more popularity among hypogonadal men. The positive effects on body composition, metabolic functions, and mental well-being can improve the quality of life of many men. However, testosterone can also trigger several side effects, including increases in hematocrit and hemoglobin levels. Exogenous testosterone tends to increase erythropoiesis. The testosterone-induced increase in red blood cells can increase performance via improved transport of oxygen to the body. However, red blood cell overproduction can cause blood clots and severe sequelae such as heart attack, stroke, or pulmonary embolism. These side effects need to be closely monitored in testosterone replacement therapy (TRT) patients. Traditionally, cessation of TRT was recommended for patients with severe polycythemia. However, cessation of TRT can lead to the recurrence of symptoms experienced before TRT. Fortunately, recent innovations in testosterone preparations allow a treatment with less side effects on hematocrit levels.

OBJECTIVES

This review focuses on highlighting novel methods to treat hypogonadism while minimizing side effects related to hematocrit levels.

METHODS

We identified relevant articles using PubMed and Google Scholar searching for specific terms from 2000-2024.

RESULTS

Elevations in hematocrit levels triggered by testosterone therapy seem to be controversial, some studies advocate noninferior effects as compared to placebo while others found adverse side effects on cardiovascular health. However, the way of administration of testosterone seems to strongly influence the extent of hematocrit increases and can therefore be minimized by choosing the right testosterone preparation.

CONCLUSION

Depending on the route of administration, testosterone replacement therapy can lead to significant increases in hematocrit and potential cardiovascular incidents. On the other hand, for hypogonadal patients with anemia, testosterone replacement therapy might be beneficial not only for restoring healthy testosterone levels but also red blood cells.

Von Willebrand factor activity levels are influenced by driver mutation status in polycythemia vera and essential thrombocythemia patients with well-controlled platelet counts

Von Willebrand factor ristocetin cofactor (VWF activity) and platelet count (PLT) are negatively correlated in patients with polycythemia vera (PV) and essential thrombocythemia (ET). However, VWF activity does not always normalize upon controlling PLT in those patients. To address this issue, we investigated the correlation between VWF activity and PLT in PV and ET patients. The negative correlation between VWF activity and PLT was stronger in calreticulin mutation-positive (CALR+) ET than in Janus kinase 2 mutation-positive (JAK2+) PV or ET groups. When PLT were maintained at a certain level (<600 × 10⁹ /L), low VWF activity (<50%) was more frequently observed in JAK2+ PV patients than in JAK2+ ET (p=0.013) or CALR+ ET (p=0.013) groups, and in PV and ET patients with ≥50% JAK2+ allele burden than in those with allele burden <50% (p=0.015). High VWF activity (>150%) was more frequent in the JAK2+ ET group than in the CALR+ ET group (p=0.005), and often associated with vasomotor symptoms (p=0.002). This study suggests that some patients with JAK2+ PV or ET have VWF activity outside the standard range even with well-controlled PLT, and that the measurement of VWF activity is useful for assessing the risk of thrombosis and hemorrhage.

High platelet-to-lymphocyte ratio may differentiate polycythemia vera from secondary polycythemia

Discriminating polycythemia vera (PV) from secondary polycythemia (SP) is crucial due to the inherent risk of thrombosis in PV and different treatment approaches. The majority of PV patients have subnormal serum erythropoietin levels and harbor Janus kinase 2 (JAK2) mutations; however, serum erythropoietin levels may be normal in approximately one third of PV patients and mutational analysis is costly and requires access to specialized laboratories. Recently, neutrophil-to-lymphocyte (NLR) and platelet-to-lymphocyte ratios (PLR) emerged as rapidly available biomarkers to identify PV patients under an increased risk of thrombosis and death. This multicenter retrospective study investigated whether these two biomarkers may also be used to differentiate PV from SP. A total of 207 subjects were included (103 PV and 104 SP) with both baseline NLR (median 4.33 vs. 1.89) and PLR (median 259.12 vs. 81.11) being significantly higher in PV than in SP (p < 0.001 for both analyses). According to the receiver operating curve analysis, PLR (area under the curve, AUC 0.936, the optimal cut-off value of > 138.1 had 82.5% sensitivity and 91.67% specificity for the detection of PV) outperformed other tested variables (NLR, total leukocytes, neutrophils, lymphocytes and platelets) and its cut-off values with 100% specificity and sensitivity were able to confirm (PLR > 224.56; 31% patients) and to exclude (PLR < 68.8; 13% patients) the highest proportions of PV patients. Therefore, PLR may represent a cheap and a rapidly available biomarker with valuable diagnostic and prognostic properties. This information may be particularly useful in resource-limited settings; however, our results need validation on larger datasets.

Advances in the Treatment of Polycythemia Vera: Trends in Disease Management

Treatment modalities for polycythemia vera (PV) have evolved over time. Phlebotomy and low-dose aspirin suffice in low-risk patients, but cytoreductive therapies are indicated in all high-risk patients (age ≥ 65 years or those with a history of PV-related thrombotic event) and may be considered for low-risk patients with progressively increasing splenomegaly, progressively increasing leucocyte and platelet counts, and for those who do not tolerate phlebotomy. Hydroxyurea/hydroxycarbamide or interferons can be used as first-line drugs. Hydroxyurea may not be tolerated by some patients, and it also carries risk of myelosuppression. Interferon alfa is especially useful for PV symptoms, and the newer preparation, ropeginterferon alfa-2b, has lesser incidence of flu-like reactions. Ruxolitinib reduces the JAK2V617F mutation burden and is used as a second-line drug. Anagrelide reduces platelet production and can be used in conjunction with hydroxyurea in patients with excessive thrombocytosis. The alkylating agent, busulfan, can also be used as a last resort in patients with a limited life expectancy. Prospective future treatments include givinostat, a histone deacetylase inhibitor, and idasanutlin, a murine double minute 2 antagonist.

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

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

New Perspectives on Polycythemia Vera: From Diagnosis to Therapy

Polycythemia vera (PV) is mainly characterized by elevated blood cell counts, thrombotic as well as hemorrhagic predisposition, a variety of symptoms, and cumulative risks of fibrotic progression and/or leukemic evolution over time. Major changes to its diagnostic criteria were made in the 2016 revision of the World Health Organization (WHO) classification, with both hemoglobin and hematocrit diagnostic thresholds lowered to 16.5 g/dL and 49% for men, and 16 g/dL and 48% for women, respectively. The main reason leading to these changes was represented by the recognition of a new entity, namely the so-called “masked PV”, as individuals suffering from this condition have a worse outcome, possibly owing to missed or delayed diagnoses and lower intensity of treatment. Thrombotic risk stratification is of crucial importance to evaluate patients’ prognosis at diagnosis. Currently, patients are stratified into a low-risk group, in the case of younger age (<60 years) and no previous thromboses, and a high-risk group, in the case of patients older than 60 years and/or with a previous thrombotic complication. Furthermore, even though they have not yet been formally included in a scoring system, generic cardiovascular risk factors, particularly hypertension, smoking, and leukocytosis, contribute to the thrombotic overall risk. In the absence of agents proven to modify its natural history and prevent progression, PV management has primarily been focused on minimizing the thrombotic risk, representing the main cause of morbidity and mortality. When cytoreduction is necessary, conventional therapies include hydroxyurea as a first-line treatment and ruxolitinib and interferon in resistant/intolerant cases. Each therapy, however, is burdened by specific drawbacks, underlying the need for improved strategies. Currently, the therapeutic landscape for PV is still expanding, and includes several molecules that are under investigation, like long-acting pegylated interferon alpha-2b, histone deacetylase inhibitors, and murine double minute 2 (MDM2) inhibitors.

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.

Givinostat: an emerging treatment for polycythemia vera

INTRODUCTION

Polycythemia vera (PV), a Philadelphia chromosome-negative myeloproliferative neoplasm, is characterized by panmyelosis, pancytosis, and a JAK2 mutation. Patients are at increased risk of thrombohemorrhagic events, and progression to myelofibrosis or acute leukemia. Current treatments include aspirin, phlebotomy, and cytoreductive drugs (most commonly hydroxyurea). Givinostat is a potent, class I/II histone deacetylase (HDAC) inhibitor that is in phase I/II clinical trials in PV. Givinostat was well tolerated and yielded promising clinico-hematological responses. A phase III study of givinostat versus hydroxyurea in high-risk PV patients is planned.

AREAS COVERED

We present an overview of PV, current treatment guidelines, and the putative mechanism(s) of action of givinostat. We discuss the preclinical and clinical studies of givinostat in PV and briefly review approved and investigational competitor compounds.

EXPERT OPINION

HDAC inhibitors have long been known to be active in PV, but chronic toxicities can be challenging. Givinostat, however, is active and well tolerated, and is entering a pivotal Phase III randomized trial. Givinostat offers the possibility of replacing hydroxyurea as the standard first-line cytoreductive choice for PV patients. This would completely change the current therapeutic paradigm and guidelines for PV management. Although surrogate clinical study endpoints may suffice for regulatory purposes, thrombosis reduction and prevention of disease progression remain most important to patients and clinicians.

Recommendations for the use of pegylated interferon-α in the treatment of classical myeloproliferative neoplasms

The classical myeloproliferative neoplasms (MPN) are uncommon clonal haemopoietic malignancies characterised by excessive production of mature blood cells. Clinically, they are associated with thrombosis, haemorrhage, varying degrees of constitutional disturbance and a risk of progression to myelofibrosis or acute myeloid leukaemia. Many of the disease manifestations may be ameliorated by treatment with interferon-α (IFN), but its use in Australian MPN patients has been limited due to the inconvenience of frequent injections and side-effects. The pegylated form of IFN is a long-acting preparation, which is better tolerated, and its Pharmaceutical Benefits Scheme listing is likely to lead to increased usage. We review the literature on risks and benefits of IFN treatment for MPN, suggest criteria for patient selection in each of these diseases and discuss strategies to manage the side-effects of pegylated IFN.

[A new case of rare erythrocytosis due to EGLN1 mutation with review of the literature]

INTRODUCTION

The origin of polycythemia is often simple to detect. Sometimes it is necessary to look for hereditary forms, the decisive parameters being the dosage of erythropoietin and the measurement of the oxygen dissociation curve (P50). These rare diseases are related to high oxygen-affinity haemoglobins, abnormalities of the erythropoietin receptor or dysfunction of the HIF (hypoxia-inducible factor) pathway.

CASE REPORT

We report the case of a 56-year-old patient with unexplained polycythemia associated with normal serum erythropoietin and normal P50, in whom the never previously described mutation c.400C>T(p.Gln134*) on exon 1 in the EGLN1 gene (encoding PHD2) was found.

CONCLUSION

In the face of an unexplained polycythemia a good cooperation between clinicians and biologists is necessary to be able to characterize rare hereditary pathologies.

Macrophage Inflammation, Erythrophagocytosis, and Accelerated Atherosclerosis in Jak2 V617F Mice

RATIONALE

The mechanisms driving atherothrombotic risk in individuals with JAK2 ^V617F ( Jak2 ^VF) positive clonal hematopoiesis or myeloproliferative neoplasms are poorly understood.

OBJECTIVE

The goal of this study was to assess atherosclerosis and underlying mechanisms in hypercholesterolemic mice with hematopoietic Jak2 ^VF expression.

METHODS AND RESULTS

Irradiated low-density lipoprotein receptor knockout ( Ldlr^-/-) mice were transplanted with bone marrow from wild-type or Jak2 ^VF mice and fed a high-fat high-cholesterol Western diet. Hematopoietic functions and atherosclerosis were characterized. After 7 weeks of Western diet, Jak2 ^VF mice showed increased atherosclerosis. Early atherosclerotic lesions showed increased neutrophil adhesion and content, correlating with lesion size. After 12 weeks of Western diet, Jak2 ^VF lesions showed increased complexity, with larger necrotic cores, defective efferocytosis, prominent iron deposition, and costaining of erythrocytes and macrophages, suggesting erythrophagocytosis. Jak2 ^VF erythrocytes were more susceptible to phagocytosis by wild-type macrophages and showed decreased surface expression of CD47, a "don't-eat-me" signal. Human JAK2VF erythrocytes were also more susceptible to erythrophagocytosis. Jak2 ^VF macrophages displayed increased expression and production of proinflammatory cytokines and chemokines, prominent inflammasome activation, increased p38 MAPK (mitogen-activated protein kinase) signaling, and reduced levels of MerTK (c-Mer tyrosine kinase), a key molecule mediating efferocytosis. Increased erythrophagocytosis also suppressed efferocytosis.

CONCLUSIONS

Hematopoietic Jak2 ^VF expression promotes early lesion formation and increased complexity in advanced atherosclerosis. In addition to increasing hematopoiesis and neutrophil infiltration in early lesions, Jak2 ^VF caused cellular defects in erythrocytes and macrophages, leading to increased erythrophagocytosis but defective efferocytosis. These changes promote accumulation of iron in plaques and increased necrotic core formation which, together with exacerbated proinflammatory responses, likely contribute to plaque instability.

How I treat polycythemia vera

Since its discovery, polycythemia vera (PV) has challenged clinicians responsible for its diagnosis and management and scientists investigating its pathogenesis. As a clonal hematopoietic stem cell (HSC) disorder, PV is a neoplasm but its driver mutations result in overproduction of morphologically and functionally normal blood cells. PV arises in an HSC but it can present initially as isolated erythrocytosis, leukocytosis, thrombocytosis, or any combination of these together with splenomegaly or myelofibrosis, and it can take years for a true panmyelopathy to appear. PV shares the same JAK2 mutation as essential thrombocytosis and primary myelofibrosis, but erythrocytosis only occurs in PV. However, unlike secondary causes of erythrocytosis, in PV, the plasma volume is frequently expanded, masking the erythrocytosis and making diagnosis difficult if this essential fact is ignored. PV is not a monolithic disorder: female patients deregulate fewer genes and clinically behave differently than their male counterparts, while some PV patients are genetically predisposed to an aggressive clinical course. Nevertheless, based on what we have learned over the past century, most PV patients can lead long and productive lives. In this review, using clinical examples, I describe how I diagnose and manage PV in an evidence-based manner without relying on chemotherapy.

The biophysics and mechanics of blood from a materials perspective

Cells actively interact with their microenvironment, constantly sensing and modulating biochemical and biophysical signals. Blood comprises a variety of non-adherent cells that interact with each other and with endothelial and vascular smooth muscle cells of the blood vessel walls. Blood cells are further experiencing a range of external forces by the hemodynamic environment and they also exert forces to remodel their local environment. Therefore, the biophysics and material properties of blood cells and blood play an important role in determining blood behaviour in health and disease. In this Review, we discuss blood cells and tissues from a materials perspective, considering the mechanical properties and biophysics of individual blood cells and endothelial cells as well as blood cell collectives. We highlight how blood vessels provide a mechanosensitive barrier between blood and tissues and how changes in vessel stiffness and flow shear stress can be correlated to plaque formation and exploited for the design of vascular grafts. We discuss the effect of the properties of fibrin on blood clotting, and investigate how forces exerted by platelets are correlated to disease. Finally, we hypothesize that blood and vascular cells are constantly establishing a mechanical homeostasis, which, when imbalanced, can lead to hematologic and vascular diseases.

Interferon Alpha Has a Strong Anti-tumor Effect in Philadelphia-negative Myeloproliferative Neoplasms

BACKGROUND

Despite the important progress in the research of myeloproliferative neoplasms (MPN), treatment options are still limited. Currently, a cytoreductive approach is the backbone treatment, with hydroxyurea (HU) being the most important agent. However, this drug is not always well-tolerated and has been questionably linked to a potential leukemogenic effect. A valid alternative is interferon alfa (IFN-α), but it is reserved for selected patients owing to the more frequent side effects and the lack of final results from the studies directly comparing IFN-α with HU, which is why we provided the results of the so far largest real-life analysis.

PATIENTS AND METHODS

From 2000 to 2016, 63 patients with Philadelphia-negative MPN prospectively received either HU or IFN-α.

RESULTS

During a median follow-up period of 121 months (range, 88-168 months), 97% of the patients treated with IFN-α achieved a hematologic response (60% complete, 37% partial) compared with 78% in the HU group (56% complete, 20% partial; P < .01). Molecular responses were limited to patients treated with IFN-α. IFN-α was well-tolerated with no secondary malignancy, whereas HU was associated with more toxic events and cases of leukemic transformation. A significantly longer progression-free survival (5.0 vs. 3.1 years; P < .001) and overall survival (7.8 vs. 5.8 years; P = .006) were observed in the IFN-α group compared with the HU cohort.

CONCLUSION

Our data support IFN-α as a more valid therapeutic option owing to its more profound hematologic responses, durable molecular remissions, long-term disease control, and reduced risk of leukemic transformation with a favorable toxicity profile.

Targeting compensatory MEK/ERK activation increases JAK inhibitor efficacy in myeloproliferative neoplasms

Constitutive JAK2 signaling is central to myeloproliferative neoplasm (MPN) pathogenesis and results in activation of STAT, PI3K/AKT, and MEK/ERK signaling. However, the therapeutic efficacy of current JAK2 inhibitors is limited. We investigated the role of MEK/ERK signaling in MPN cell survival in the setting of JAK inhibition. Type I and II JAK2 inhibition suppressed MEK/ERK activation in MPN cell lines in vitro, but not in Jak2V617F and MPLW515L mouse models in vivo. JAK2 inhibition ex vivo inhibited MEK/ERK signaling, suggesting that cell-extrinsic factors maintain ERK activation in vivo. We identified PDGFRα as an activated kinase that remains activated upon JAK2 inhibition in vivo, and PDGF-AA/PDGF-BB production persisted in the setting of JAK inhibition. PDGF-BB maintained ERK activation in the presence of ruxolitinib, consistent with its function as a ligand-induced bypass for ERK activation. Combined JAK/MEK inhibition suppressed MEK/ERK activation in Jak2V617F and MPLW515L mice with increased efficacy and reversal of fibrosis to an extent not seen with JAK inhibitors. This demonstrates that compensatory ERK activation limits the efficacy of JAK2 inhibition and dual JAK/MEK inhibition provides an opportunity for improved therapeutic efficacy in MPNs and in other malignancies driven by aberrant JAK-STAT signaling.

Recommendations for the diagnosis and treatment of patients with polycythaemia vera

OBJECTIVES

To present the Central European Myeloproliferative Neoplasm Organisation (CEMPO) treatment recommendations for polycythaemia vera (PV).

METHODS

During meetings held from 2015 through 2017, CEMPO discussed PV and its treatment and recent data.

RESULTS

PV is associated with increased risks of thrombosis/thrombo-haemorrhagic complications, fibrotic progression and leukaemic transformation. Presence of Janus kinase (JAK)-2 gene mutations is a diagnostic marker and standard diagnostic criterion. World Health Organization 2016 diagnostic criteria for PV, focusing on haemoglobin levels and bone marrow morphology, are mandatory. PV therapy aims at managing long-term risks of vascular complications and progression towards transformation to acute myeloid leukaemia and myelodysplastic syndrome. Risk stratification for thrombotic complications guides therapeutic decisions. Low-risk patients are treated first line with low-dose aspirin and phlebotomy. Cytoreduction is considered for low-risk (phlebotomy intolerance, severe/progressive symptoms, cardiovascular risk factors) and high-risk patients. Hydroxyurea is suspected of leukaemogenic potential. IFN-α has demonstrated efficacy in many clinical trials; its pegylated form is best tolerated, enabling less frequent administration than standard interferon. Ropeginterferon alfa-2b has been shown to be more efficacious than hydroxyurea. JAK1/JAK2 inhibitor ruxolitinib is approved for hydroxyurea resistant/intolerant patients.

CONCLUSIONS

Greater understanding of PV is serving as a platform for new therapy development and treatment response predictors.

Health Care Costs and Thromboembolic Events in Hydroxyurea-Treated Patients with Polycythemia Vera

BACKGROUND

Patients with polycythemia vera (PV) are at increased risk of thromboembolic events (TEs), which are key contributors to reduced overall survival compared with the age- and sex-matched general population. In addition to aspirin and phlebotomy to maintain hematocrit level < 45%, many patients receive cytoreduction with hydroxyurea (HU), which is associated with improved survival and may reduce the risk of cardiovascular events and TEs. However, 1 in 4 patients become resistant to or intolerant of HU. In the general population, prophylaxis and treatment following arterial and venous thromboses are associated with increased health care resource utilization and costs.

OBJECTIVE

To describe the health care resource utilization and costs associated with TEs in patients with PV treated with HU in the United States.

METHODS

This retrospective cross-sectional analysis of the Truven Health Analytics MarketScan Research Databases included adult patients with a PV diagnosis who were newly treated with HU and continuously enrolled in medical and pharmacy benefit plans for ≥ 12 months pre- and post-index. HU treatment administration, persistence, adherence, and related adverse events, as well as TEs, were reported during the 12-month follow-up period. HU treatment patterns were further analyzed in a subgroup analysis comparing patients with and without a ≥ 45-day gap in HU treatment. Health care resource utilization and costs were analyzed in a subgroup analysis comparing patients who had TEs in the 12-month follow-up period with those who did not. Tests for statistically significant differences across the comparison groups were conducted, including chi-square tests for categorical variables and t-tests for continuous variables.

RESULTS

The records of 1,322 patients with PV were included in this study. Mean age was 66.0 years; 51.3% were men; and 14.0% had a history of TEs. During the first year of HU treatment, 764 (57.8%) patients had a treatment gap of ≥ 45 days; however, treatment adherence was similar between those with and those without a gap (85.2% vs. 90.7%, respectively). TEs occurred in 216 (16.3%) patients within 12 months of HU initiation. Health care resource utilization was higher for patients with TEs versus those without, including the proportion of patients requiring inpatient services (50.9% vs. 18.4%; P < 0.001) and emergency room visits (48.1% vs. 26.3%; P < 0.001) and the mean number of inpatient admissions (1.7 vs. 1.3; P = 0.004); office visits (18.9 vs. 14.1; P < 0.001); and prescriptions (45.8 vs. 36.2; P<0.001). In addition, total mean health care costs ($45,040 vs. $16,438; P < 0.001); inpatient costs ($18,952 vs. $4,794; P < 0.001); outpatient costs ($20,844 vs. $8,046; P < 0.001); and outpatient pharmacy costs ($5,244 vs. $3,598; P = 0.002) were higher among patients with TEs than those without.

CONCLUSIONS

Patients with PV receiving treatment with HU remain at risk for TEs. The occurrence of TEs during the 12-month follow-up in this patient population was associated with higher health care resource utilization and costs.

DISCLOSURES

This study was funded by Incyte Corporation. Parasuraman and Paranagama are employees and stockholders of Incyte Corporation. Shi and Bonafede are employees of Truven Health Analytics, which was awarded a research contract to conduct this study with and on behalf of Incyte Corporation. Study concept and design were contributed by all of the authors, who also interpreted the data and wrote and revised the manuscript. Bonafede and Shi collected the data. This study was presented as an abstract at the Academy of Managed Care Pharmacy NEXUS Annual Meeting on October 26-29, 2015, in Orlando, Florida.

Antithrombotic therapy for venous thromboembolism in myeloproliferative neoplasms

In myeloproliferative neoplasms (MPNs) the incidence of venous thromboembolism (VTE) is 0.6–1.0 per 100 pt-years, and the rate of recurrence after VTE is 6.0–6.5 per 100 pt-yrs. Vitamin K-antagonists (VKA) reduces the risk of recurrence after VTE at usual sites (i.e., deep venous thrombosis (DVT) of the legs and pulmonary embolism (PE)) by 48–69%, with a rate of recurrent thrombosis per 100 pt-yrs of 3.4–4.7 on VKA and 8.9–9.6 off VKA; VKA discontinuation produces a 2.2-fold increased risk of novel thrombotic events with respect to continuation. However, the rate of both recurrent thrombosis and major bleeding on VKA is higher in MPN patients than in non-MPN patients, and the risk-benefit balance of long-term VKA treatment is challenging. In the absence of strong evidence, the tailored management of MPN-related VTE should operatively consider the risk categories for recurrence and bleed well established in the non-MPN setting. In summary, MPN patients with VTE are candidates for life-long VKA treatment, especially after unprovoked proximal DVT and PE. Aspirin can offer a moderate benefit in those patients who stop anticoagulation. The use of direct oral anticoagulants should be explored aiming to ameliorate the rate of bleeding.

Ruxolitinib for the treatment of inadequately controlled polycythemia vera without splenomegaly: 80-week follow-up from the RESPONSE-2 trial

RESPONSE-2 is a phase 3 study comparing the efficacy and safety of ruxolitinib with the best available therapy (BAT) in hydroxyurea-resistant/hydroxyurea-intolerant polycythemia vera (PV) patients without palpable splenomegaly. This analysis evaluated the durability of the efficacy and safety of ruxolitinib after patients completed the visit at week 80 or discontinued the study. Endpoints included proportion of patients achieving hematocrit control (< 45%), proportion of patients achieving complete hematologic remission (CHR) at week 28, and the durability of hematocrit control and CHR. At the time of analysis, 93% (69/74) of patients randomized to ruxolitinib were receiving ruxolitinib; while in the BAT arm, 77% (58/75) of patients crossed over to ruxolitinib after week 28. No patient remained on BAT by week 80. Among patients who achieved a hematocrit response at week 28, the probability of maintaining response up to week 80 was 78% in the ruxolitinib arm. At week 80, durable CHR was achieved in 18 patients (24%) in the ruxolitinib arm versus 2 patients (3%) in the BAT arm. The safety profile of ruxolitinib was consistent with previous reports. These data support that ruxolitinib treatment should be considered also as a standard of care for hydroxyurea-resistant/hydroxyurea-intolerant PV patients without palpable splenomegaly.

Allogeneic stem-cell transplantation for myelofibrosis

PURPOSE OF REVIEW

Allogeneic hematopoietic stem-cell transplantation (HSCT) remains the only curative therapy for myelofibrosis. The number of HSCTs performed for this indication has been steadily increasing over the past years, even after the approval of the Janus kinase (JAK) inhibitor, ruxolitinib. This increase may be attributed to improved patient selection based on new prognostic molecular markers, more frequent use of matched unrelated donors, secondary to better (high-resolution) human leukocyte antigen typing and supportive care. Ruxolitinib approval raises new questions regarding the role of JAK inhibitors in the transplant setting.

RECENT FINDINGS

The current review summarizes recent updates on HSCT in myelofibrosis. Predictors for transplant outcomes, and specific considerations related to myelofibrosis patient selection for HSCT (e.g. molecular risk stratification) are reviewed. In addition, this review will consider management of myelofibrosis patients in the peritransplant period, including the role of ruxolitinib in the pretransplant period, pre and posttransplant splenomegaly, transplant protocols, posttransplant follow-up of minimal residual disease and interventions in the event of poor engraftment.

SUMMARY

HSCT remains a highly relevant treatment option for myelofibrosis in the era of JAK inhibitors. Recent advances may contribute to a refined definition of HSCT eligibility and identification of the optimal transplantation time, conditioning protocols and posttransplant management.

SOHO State-of-the-Art Update and Next Questions: MPN

The discovery of the activating Janus kinase (JAK)2V617F mutation in 2005 in most patients with the classic Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) spurred intense interest in research into these disorders, culminating in the identification of activating mutations in MPL in 2006 and indels in the gene encoding calreticulin (CALR) in 2013, thus providing additional mechanistic explanations for the universal activation of JAK-signal transducer and activator of transcription (JAK-STAT) observed in these conditions, and the success of the JAK1/2 inhibitor ruxolitinib, which first received regulatory approval in 2011. The field has continued to advance rapidly since then, and the past 2 years have witnessed important changes to the classification of MPN and diagnostic criteria for polycythemia vera (PV), novel insights into the mechanisms of bone marrow fibrosis in primary myelofibrosis (PMF), increasing appreciation of the biologic differences between essential thrombocythemia (ET), prefibrotic and overt PMF, and between primary and post-PV/ET myelofibrosis (MF). Additionally, the mechanisms through which mutant CALR drives JAK-STAT pathway activation and oncogenic transformation are now better understood. Although mastocytosis is no longer included under the broad heading of MPN in the 2016 revision to the World Health Organization classification, an important milestone in mastocytosis research was reached in 2017 with the regulatory approval of midostaurin for patients with advanced systemic mastocytosis (AdvSM). In this article, we review the major recent developments in the areas of PV, ET, and MF, and also briefly summarize the literature on midostaurin and other KIT inhibitors for patients with AdvSM.

Disease and treatment characteristics of polycythemia vera patients in Belgium: Results from a scientific survey

OBJECTIVE

The current survey aimed to gather predefined disease parameters and treatment strategies to characterize the polycythemia vera (PV) patient population in Belgium.

METHODS

Cross-sectional data from PV patients, seen at least once between May 2014 and May 2015 at 10 sites in Belgium, were collected in aggregated form and analyzed descriptively and quantitatively.

RESULTS

Data from 343 PV patients were collected. Of these, 174 (50.7%) were male and 256 (74.6%) were ≥60 years of age. Ninety-two (26.8%) had a prior history of thrombotic events. Considerable proportions of patients had increased hematological parameters (hematocrit > 45% [31.2%], leukocytes > 10 × 10⁹ /L [33.3%], and platelet > 400 × 10⁹ /L [38.2%]). Most patients had non-palpable spleen (284, 87.7%) and no phlebotomies during the past 6 months (197, 57.4%). Low-dose aspirin was given as thrombosis prophylaxis in 249 (72.6%) patients, while 232 (67.6%) received hydroxyurea (HU) as cytoreductive treatment. Forty-one patients (12.0%) were reported as resistant and/or intolerant to HU. Seventeen patients (5.0%) received ruxolitinib in the context of clinical trials.

CONCLUSION

This survey provides better insight into the characteristics of Belgian PV patients and currently used treatment strategies. It shows that 232 (67.6%) PV patients continue to receive HU despite being potentially HU-resistant.

Hydroxyurea: Analytical techniques and quantitative analysis

Hydroxyurea is a potent disease-modifying therapeutic agent with efficacy for the treatment of sickle cell anemia. When administered at once-daily oral doses that lead to mild marrow suppression, hydroxyurea leads to substantial and sustained fetal hemoglobin induction, which effectively inhibits erythrocyte sickling. When escalated to maximum tolerated dose, hydroxyurea has proven laboratory and clinical effects for both children and adults with sickle cell anemia. However, there is substantial inter-patient variability with regard to the optimal dosing regimen, as well as differences in treatment-related toxicities and responses that may be explained by hydroxyurea pharmacokinetics and pharmacogenetics. Addressing the safety and efficacy of hydroxyurea treatment requires quantitative and accurate drug analysis, and various laboratory techniques have been established. We review the historical and current analytical techniques for measuring hydroxyurea concentrations accurately, and discuss clinical settings where quantitative analysis can increase understanding and safety of this important therapeutic agent, and ultimately improve patient outcomes.

Developmental Therapeutics in Myeloproliferative Neoplasms

The unprecedented success of the Janus kinase (JAK) 1/2 inhibitor ruxolitinib in myelofibrosis (MF) provided much-needed impetus for clinical drug development for the Philadelphia chromosome-negative myeloproliferative neoplasms. The survival benefit conferred by this agent, along with its marked efficacy with regard to spleen volume and symptom reduction, have made ruxolitinib the cornerstone of drug therapy in MF. However, there remain significant unmet needs in the treatment of patients with MF, and many novel classes of agents continue to be investigated in efforts to build on the progress made with ruxolitinib. These include inhibitors of histone deacetylases (HDACs) and DNA methyltransferases, phosphatidylinositol-3-kinase isoforms, heat shock protein 90, cyclin-dependent kinases 4/6, and Hedgehog signaling, among others. In parallel, other JAK inhibitors with potential for less myelosuppression or even improvement of anemia, greater selectivity for JAK1 or JAK2, and the ability to overcome JAK inhibitor persistence are in various stages of development. First-in-class agents such as the activin receptor IIA ligand trap sotatercept (for anemia of MF), the telomerase inhibitor imetelstat, and the antifibrotic agent PRM-151 (recombinant human pentraxin-2) are also in clinical trials. In polycythemia vera, a novel interferon administered every 2 weeks is being developed for front-line therapy in high-risk individuals, and inhibitors of human double minute 2 (HDM2) have shown promise in preclinical studies, as have HDAC inhibitors such as givinostat (both in the laboratory and in the clinic). Ruxolitinib is approved for second-line therapy of polycythemia vera and is being developed for essential thrombocythemia.

Detection of driver and subclonal mutations in myelofibrosis: clinical impact on pharmacologic and transplant based treatment strategies

INTRODUCTION

Myelofibrosis (MF) is the most aggressive form among Philadelphia negative (Ph-) myeloproliferative neoplasms (MPNs). In the last years, the mutational landscape of MF has expanded remarkably by the identification of additional recurrent mutations, called subclonal mutations. Areas covered: Here we describe the available data about the currently identified subclonal mutations and their prognostic value in MF patients. We also review the practical value of including such molecular information in available prognostic models for both outcome prediction and possibly treatment decision with regards to transplant indication. Lastly, we covered the available data on the application of molecular markers for minimal residual disease (MRD) monitoring after transplantation. Expert commentary: The demonstration of the prognostic value of additional mutations suggests to define this molecular profile at diagnosis and when an allogeneic transplant can be advised, particularly in younger patients. The presence of molecular markers might offer the possibility to evaluate the depth of remission and to monitor MRD after transplantation. Prospective clinical studies are needed to validate the use of this molecular data in the routine clinical practice.

Experience with ruxolitinib in the treatment of polycythaemia vera

Polycythaemia vera (PV) is a myeloproliferative neoplasm classically characterized by an erythrocytosis and is associated with a high risk of thromboembolic events, constitutional symptoms burden and risk of transformation to myelofibrosis and acute myeloid leukaemia. Therapy is directed at the haematocrit (HCT) to reduce the risk of thrombotic events and usually comprises low-dose aspirin and phlebotomy to maintain HCT at >45%. Frequently in addition, cytoreductive therapy is indicated in high-risk patients for normalizing haematological parameters to mitigate the occurrence of thromboembolic events. Unfortunately, there is no clear evidence that current therapies reduce the risk of transformation to myelofibrosis and for some a risk of a therapy related complication is unknown for example leukaemia due to hydroxycarbamide (HC). First-line therapy for treating PV remains HC or interferon, the latter most often in younger patients, especially those of childbearing age. However, therapy related intolerance or resistance is a common feature and results in limited treatment options for such patients. The discovery of the JAK2 V617F mutation and consequently targeted therapy with Janus kinase inhibitors, in particular ruxolitinib, has extended the spectrum of agents that can be used as second or third line in PV. The findings of the phase II trial RESPONSE and the preliminary data from RESPONSE 2 trial have identified a role for ruxolitinib in PV patients who are resistant or intolerant to HC. In this article, using clinical cases we demonstrate our experience with ruxolitinib highlighting the clinical benefits and limitations we encountered in clinical practice.

Polycythemia Vera Management and Challenges in the Community Health Setting

Patients with polycythemia vera (PV) experience shortened survival, increased risk of thromboembolic and hemorrhagic events, and burdensome symptoms. For all patients with PV, treatment with aspirin and hematocrit control with phlebotomy are recommended. In addition, patients with high-risk status or poor hematocrit control benefit from cytoreductive therapy with hydroxyurea, although approximately 1 in 4 patients develops resistance or intolerance. For patients who are resistant to or intolerant of hydroxyurea, studies have shown that ruxolitinib, a Janus kinase 1/2 inhibitor, provides hematocrit control, reduces spleen size, normalizes blood counts, and improves PV-related symptoms. For many patients, PV is managed in a community health setting, and it is important that community hematologists, oncologists, and internists are familiar with the contemporary management of PV to improve patient outcomes, including management for patients who present with unique health-care needs. This review provides an overview of current treatment options for patients with PV and discusses challenging circumstances encountered by community providers in the management of PV, including symptom assessment, identification of hydroxyurea resistance/intolerance, pregnancy, elective surgeries, concomitant immunosuppressants, and managing patients in areas with limited access to specialized hematologic care.

The efficacy and safety of continued hydroxycarbamide therapy versus switching to ruxolitinib in patients with polycythaemia vera: a randomized, double-blind, double-dummy, symptom study (RELIEF)

The randomized, double-blind, double-dummy, phase 3b RELIEF trial evaluated polycythaemia vera (PV)-related symptoms in patients who were well controlled with a stable dose of hydroxycarbamide (also termed hydroxyurea) but reported PV-related symptoms. Patients were randomized 1:1 to ruxolitinib 10 mg BID (n = 54) or hydroxycarbamide (prerandomization dose/schedule; n = 56); crossover to ruxolitinib was permitted after Week 16. The primary endpoint, ≥50% improvement from baseline in myeloproliferative neoplasm -symptom assessment form total symptom score cytokine symptom cluster (TSS-C; sum of tiredness, itching, muscle aches, night sweats, and sweats while awake) at Week 16, was achieved by 43·4% vs. 29·6% of ruxolitinib- and hydroxycarbamide-treated patients, respectively (odds ratio, 1·82; 95% confidence interval, 0·82-4·04; P = 0·139). The primary endpoint was achieved by 34% of a subgroup who maintained their hydroxycarbamide dose from baseline to Weeks 13-16. In a post hoc analysis, the primary endpoint was achieved by more patients with stable screening-to-baseline TSS-C scores (ratio ≤ 2) receiving ruxolitinib than hydroxycarbamide (47·4% vs. 25·0%; P = 0·0346). Ruxolitinib treatment after unblinding was associated with continued symptom score improvements. Adverse events were primarily grades 1/2 with no unexpected safety signals. Ruxolitinib was associated with a nonsignificant trend towards improved PV-related symptoms versus hydroxycarbamide, although an unexpectedly large proportion of patients who maintained their hydroxycarbamide dose reported symptom improvement.

[Abdominal pain and hypertension in a 55-year-old male patient]

A 55-year-old male patient under permanent testosterone therapy for hypogonadism presented with abdominal pain and increased blood pressure values. In the physical examination a plethora was noted and laboratory examinations revealed polyglobulia. In the subsequent diagnostic process polycythemia vera and cancer could be excluded as the cause. A secondary polyglobulia due to testosterone substitution was diagnosed. Unphysiologically high testosterone levels represent a rare cause of secondary polyglobulia and with an appropriate medical history should be taken into account at an early stage.

New molecular genetics in the diagnosis and treatment of myeloproliferative neoplasms

PURPOSE OF REVIEW

Myeloproliferative neoplasms (MPN) are conditions of great interest because of the identification of their molecular basis and of the entering of new small molecules into clinical practice. The aim of this review is to report the role of mutations in the diagnosis, prognosis, and in the prediction of response to JAK inhibitors in MPN.

RECENT FINDINGS

New mutations of the CALR gene have been discovered in patients without JAK2 or MPL mutations and are now included in the World Health Organization classification system. The role of ASXL1 and SRSF2 together with the driver mutations is emerging in the prognostication of myelofibrosis.

SUMMARY

A wide mutational analysis of MPN helps to define diagnosis and prognosis. In the future, clinical trials based on a robust valuation of mutations will guide treatment decision-making towards precision medicine.

Polycythemia vera masked due to severe iron deficiency anemia

Polycythemia vera is one of the chronic myeloproliferative diseases and very few patients present with its actual clinical manifestations. The most common findings are increased red cell mass and an increased leukocyte count with decreased erythropoietin. We present a case where there was a delay in the diagnosis of polycythemia because of menorrhagia in the past. On admission, the patient presented with elevated red and white blood cell counts, erythropoietin was low, and polycythemia was then suspected. A bcr-abl test was performed to rule out chronic myelogenous leukemia. JAK2 mutation was positive, and the patient was diagnosed with polycythemia vera.

Characteristics and treatment of polycythemia vera patients in clinical practice: a multicenter chart review on 1476 individuals in Germany

PURPOSE

Treatment recommendations for patients with polycythemia vera (PV) are well established. Most multicenter trials investigating novel therapeutic strategies for PV are developed and conducted at university hospitals and specialized academic centers. The majority of patients in Germany, however, are treated in an outpatient (ambulatory) setting. The aim of this study was to evaluate the 'real-life' situation in a cohort of 1467 patients by analyzing data from a survey conducted at private practices and primary care centers.

METHODS

Eligible private practices and primary care centers treating patients with MPN were recruited to participate in a paper-pencil-based survey conducted from March 2015 until March 2016 in Germany. Hematologists were asked to report from patient charts. Descriptive analyses were conducted to assess for outcomes examined by reported prognostic risk scores, symptom scores and clinical response criteria.

RESULTS

In total, 34 centers participated in our retrospective survey and provided data on 1476 patients. Most patients were of older age (66.7 % older than 66 years of age), which was the main risk factor according to the criteria published by Tefferi and colleagues. Molecular status at diagnosis was not evaluated in 23 % of patients. Low rates of constitutional symptoms were reported in this physician-based survey with concentration problems, fatigue and itching being the main PV-related symptoms. Phlebotomy and hydroxyurea were the main cytoreductive measures for hematocrit control. The majority of patients were responsive (67.8 %) and tolerant (77.3 %) to hydroxyurea therapy. Interferon and JAK inhibitor therapy were used in <10 % of patients, respectively. Overall, leukocytosis, thrombocytosis and hematocrit could be effectively controlled by any therapy applied. Lack of efficacy was reported on reduction of constitutional symptoms and splenomegaly.

CONCLUSIONS

The patient population investigated was older than participants in published large multicenter trials. The majority of patients were categorized as 'high risk.' Age was the main risk factor. Molecular status was unavailable in the majority of patients diagnosed prior to 2008. The physician-based survey reported on significantly lower rates of constitutional symptoms than patient-based surveys in the literature. Consistent with previously published reports, hydroxyurea is the main agent used for PV therapy in an outpatient setting resulting in efficient control of hematopoietic parameters. Constitutional symptoms and splenomegaly, however, may not be reduced efficiently, which could be improved by the use of JAK inhibitor treatment for high-risk patients in the future.

Ruxolitinib is effective in patients with intermediate-1 risk myelofibrosis: a summary of recent evidence

Ruxolitinib is the only therapy with an approved indication for myelofibrosis (MF), a myeloproliferative neoplasm associated with progressive bone marrow fibrosis and extramedullary hematopoiesis. Although the pivotal phase 3 COMFORT studies included only patients with intermediate-2 or high-risk MF, the US indication includes all patients with intermediate- or high-risk disease. Data from recent nonrandomized studies confirm that the benefits of ruxolitinib established in the COMFORT studies in terms of spleen size reduction and symptom improvement also extend to patients with intermediate-1 risk MF, who tend to have less advanced disease than patients with higher-risk MF. Given the disease-modifying potential of ruxolitinib therapy, timely initiation of ruxolitinib therapy may not only improve patients' current clinical status but also lead to better long-term outcomes. The decision of whether or when to initiate ruxolitinib treatment should be based on the expected benefit-risk ratio for each patient, specifically considering potential adverse effects.

Acute promyelocytic leukemia co-existing with JAK2 V617F positive myeloproliferative neoplasm: a case report

The V617F mutation of Janus-associated kinase 2 (JAK2) is commonly seen in myeloproliferative neoplasms (MPN). Transformation of JAK2 positive MPNs to acute leukemia has been reported. We here report a case of acute promyelocytic leukemia which was later confirmed to have a co-existing JAK2 V617F positive MPN. In addition, the patient was found to have FLT3-TKD mutation, which, together with PML/RARa, could play a role in the MPN transformation to APL.

Contemporary insights into the pathogenesis and treatment of chronic myeloproliferative neoplasms

This review is based on the deliberations at the 5th John Goldman Colloquium held in Estoril on 2nd October 2015 and the 9th post-ASH International Workshop on chronic myeloid leukemia (CML) and BCR-ABL1-negative myeloproliferative neoplasms (MPN) which took place on the 10th-11th December 2014, immediately following the 56th American Society of Hematology Annual Meeting. It has been updated since and summarizes the most recent advances in the biology and therapy of these diseases, in particular updates of genetics of MPN, novel insights from mouse MPN models, targeting CML stem cells and its niche; clinical advances include updates on JAK2 inhibitors and other therapeutic approaches to BCR-ABL1-negative MPNs, the use of alpha interferons, updates on tyrosine kinase inhibitors (TKI) randomized trials in CML, TKI cessation studies, and optimal monitoring strategies.

Second line therapies in polycythemia vera: What is the optimal strategy after hydroxyurea failure?

Cytoreductive therapies have traditionally been the standard treatment for older patients with polycythemia vera (PV) or those with a history of prior thrombosis. Hydroxyurea (HU) is the most frequently used cytoreductive agent in PV. However, approximately 24% of patients treated with HU will eventually develop resistance or intolerance and patients who fail HU have an increased risk of death, transformation to myelofibrosis or acute myeloid leukemia. Interferon-alpha has been used in younger PV patients and is capable of inducing a complete hematologic response and significant reductions, or even eradication, of JAK2 V617F mutation allele burdens in a small but notable subset of PV patients. The potential toxicities of interferon-alpha must be weighed against the disease control benefit in a case-by-case fashion. Recently JAK2 inhibitor, ruxolitinib, demonstrated significant improvement in controlling the hematocrit and splenomegaly versus best available therapy in patients with PV who failed or are intolerant to HU and currently is FDA-approved in this setting. In this review, we will discuss novel emerging therapies for PV with a special focus on the currently available and upcoming treatment options for patients who fail HU.

The 2016 revision of WHO classification of myeloproliferative neoplasms: Clinical and molecular advances

Clinical evidence supports the need of changing the diagnostic criteria of the 2008 updated WHO classification for polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). In JAK2-mutated patients who show characteristic bone marrow (BM) morphology, clinical studies demonstrated that a hemoglobin level of 16.5g/dL in men and 16.0g/dl for women or a hematocrit value of 49% in men and 48% in women are the optimal cut off levels for distinguishing JAK2-mutated ET from "masked/prodromal" PV. Therefore BM morphology was upgraded to a major diagnostic criterion. Regarding ET the key issue was to improve standardization of prominent BM features enhancing differentiation between "true" ET and prefibrotic/early primary myelofibrosis (prePMF). These two entities have shown a different epidemiology and clinical outcomes. Concerning prePMF a more explicit clinical characterization of minor criteria is mandated for an improved distinction from ET and overt PMF and accurate diagnosis and outcome prediction.

Ruxolitinib: a targeted treatment option for patients with polycythemia vera

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm characterized by erythrocytosis and the presence of Janus kinase (JAK) 2V617F or similar mutations. This review summarizes the pathophysiology of PV, the challenges associated with traditional treatment options, and the scientific rationale and supportive clinical evidence for targeted therapy with ruxolitinib. Accumulating evidence indicates that activating mutations in JAK2 drive the PV disease state. Traditional PV treatment strategies, including aspirin, phlebotomy, and cytoreduc­tive agents such as hydroxyurea, provide clinical benefits for some but not all patients and may not adequately treat PV-related symptoms. Furthermore, traditional treatment approaches are associated with potential side effects that may limit their usage and lead some patients to discon­tinue the treatment. Ruxolitinib is an orally available small-molecule tyrosine kinase inhibitor that is a potent and selective inhibitor of JAK1/JAK2. Ruxolitinib is approved in the US for patients with PV with an inadequate response or intolerance to hydroxyurea and in Europe for adults with PV who are resistant to or intolerant of hydroxyurea. In the Phase III RESPONSE registration trial, ruxolitinib was superior to the best available therapy in patients with PV who were resistant to or intolerant of hydroxyurea in controlling hematocrit levels, reducing spleen volume, and improving PV-related symptoms and quality-of-life measures. The most common nonhematologic adverse events in ruxolitinib-treated patients were headache, diarrhea, pruritus, and fatigue in the RESPONSE trial; hematologic adverse events were primarily grade 1 or 2. In the Phase IIIb nonregistration RELIEF trial, there were nonsignificant trends toward an improved symptom control in patients with PV on a stable hydroxyurea dose who were generally well controlled but reported disease-associated symptoms and switched to ruxolitinib vs those who continued hydroxyurea therapy. Updated treatment guidelines will be important for educating physicians about the role of ruxolitinib in the treatment of patients with PV.

Pacritinib: a new agent for the management of myelofibrosis?

INTRODUCTION

Myelofibrosis (MF) is a clonal haematological disease associated with recurrent somatic gene mutations (JAK2V617F, MPL, CALR) and constitutive activation of the Janus kinase (JAK)/Signal Transducer and Activator of Transcription pathway. MF is often characterised by debilitating symptoms and JAK inhibitors (JAKIs) have revolutionised available therapeutic options. Ruxolitinib, a JAK1 and 2 inhibitor, is the only currently approved agent. Several other JAKIs are undergoing evaluation in the clinical trial setting and Pacritinib , a novel JAK2 and FLT3 inhibitor, is at an advanced stage of investigation with recent completion of a Phase III trial and another ongoing.

AREAS COVERED

Within this article we focus on pacritinib, summarising the development, preclinical and up-to-date results from the Phase I - III trials. We present the most recent data on efficacy and safety and indirectly compare this novel JAKI with ruxolitinib.

EXPERT OPINION

The kinome array data for pacritinib suggests that it has a range of targets differing to those for ruxolitinib. Pacritinib appears to be an effective agent for the control of MF-related symptoms and splenomegaly with potentially fewer haematological side-effects when compared with ruxolitinib and seems a particularly promising agent for anaemic and thrombocytopenic patients. It is also an attractive drug for potential combination studies due to its good tolerability.

Optimal therapy for polycythemia vera and essential thrombocythemia: Preferred use of interferon therapy based on phase 2 trials

OBJECTIVES

To determine the value of recombinant interferon-alfa (rIFNα) in the treatment of polycythemia vera (PV) and essential thrombocythemia (ET) based on its biological activities and phase 2 clinical studies, pending completion of phase 3 trials; to determine importance of the Internet in patient decision-making in treatment selection.

RESULTS

The value of rIFNα in PV and ET is based upon its biological effects on PV stem cells and megakaryocyte proliferation. Single-arm trials are useful for life-threatening diseases when there are relatively few patients to evaluate endpoints, such as rIFNα treatment of PV and ET. Proper diagnostic criteria are mandatory; for PV, the current World Health Organization criteria emphasizing increased hemoglobin values exclude approximately one-third of eligible patients. Importance of these data: Single-arm studies in diseases exemplified by rIFNα in PV require updated diagnostic criteria for research and for clinical practice. The influence of the Internet on patient decisions for treatment is noteworthy.

CONCLUSION

The biologic basis for selecting therapy is exemplified by rIFNα in treating PV and ET. Current single-arm studies of rIFNα in PV and ET are relevant and acceptable. The importance of the Internet in patient decision-making is important.

From Philadelphia-Negative to JAK2-Positive: Effect of Genetic Discovery on Risk Stratification and Management

The 2005 discovery of the JAK2 mutation redefined the diagnosis and natural history of myeloproliferative neoplasms (MPNs). Most importantly, this improvement in the pathobiologic conceptualization has focused our evolution of this field from being defined as what it is not (e.g., Philadelphia [Ph]-negative) to what it is (e.g., JAK2-positive, CALR-positive) in the majority of MPN cases. In the ensuing 10 years, the field has experienced a paradigm shift in terms of understanding of the biologic basis of the development of MPNs, an explosion of knowledge of the genetics of MPNs, and has translated disease knowledge into effective targeted therapies. With greater uniformity and agreement on the diagnosis and differences among the individual MPNs, augmented by improved cytogenetic and molecular classification, attention has turned now to addressing the need for uniformity in risk stratification of patients in the clinic for both disease complications and disease transformation. This article will highlight the developments in the field with regard to risk stratification and prognostication in MPNs with focus on the clinical aspects of the patient who presents with either essential thrombocytosis (ET), polycythemia vera (PV), or myelofibrosis (MF).