Severe thrombocytopenia (platelets <50 × 109/L) is associated with very poor outcome of patients with myelofibrosis (MF). As patients with primary myelofibrosis (PMF) differ from patients with ...postessential thrombocythemia (PET‐MF) and postpolycythemia vera myelofibrosis (PPV‐MF), we aimed to evaluate the significance of low platelets among these patients. We present clinical characteristics and outcome of patients with either PMF, PPV‐MF, or PET‐MF, and thrombocytopenia who presented to our institution between 1984 and 2015. Of 1269 patients (877 PMF, 212 PPV‐MF, 180 PET‐MF), 11% and 14% had platelets either <50 × 109/L or between 50‐100 × 109/L, respectively. Patients with platelets <50 × 109/L were most anemic and transfusion dependent, had highest blast count and unfavorable karyotype. In general, their overall and leukemia‐free survival was the shortest with median time of 15 and 13 months, respectively; with incidence of acute leukemia almost twice as high as in the remaining patients (6.9 vs 3.6 cases per 100 person‐years). Nevertheless, this observation remains mostly significant for patients with PMF, as those with PEV/PVT‐MF have already significantly inferior prognosis with platelets <100 × 109/L.
Interferon-alpha (rIFNα) is the only disease-modifying treatment for polycythemia vera (PV), but whether or not it prolongs survival is unknown. This large single center retrospective study of 470 PV ...patients compares the myelofibrosis-free survival (MFS) and overall survival (OS) with rIFNα to two other primary treatments, hydroxyurea (HU) and phlebotomy-only (PHL-O). The median age at diagnosis was 54 years (range 20-94) and the median follow-up was 10 years (range 0-45). Two hundred and twenty-nine patients were women (49%) and 208 were high-risk (44%). The primary treatment was rIFNα in 93 (20%), HU in 189 (40%), PHL-O in 133 (28%) and other cytoreductive drugs in 55 (12%). The treatment groups differed by ELN risk score (p < 0.001). In low-risk patients, 20-year MFS for rIFNα, HU, and PHL-O was 84%, 65% and 55% respectively (p < 0.001) and 20-year OS was 100%, 85% and 80% respectively (p = 0.44). In high-risk patients, 20-year MFS for rIFNα, HU, and PHL-O was 89%, 41% and 36% respectively (p = 0.19) and 20-year OS was 66%, 40%, 14% respectively (p = 0.016). In multivariable analysis, longer time on rIFNα was associated with a lower risk of myelofibrosis (HR: 0.91, p < 0.001) and lower mortality (HR: 0.94, p = 0.012). In conclusion, this study supports treatment of PV with rIFNα to prevent myelofibrosis and potentially prolong survival.
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.
Summary
We assessed the diagnostic performances of erythropoietin and JAK2 mutations in 1,090 patients with suspected polycythemia who were referred for red cell mass (RCM) measurement. In patients ...with a high haematocrit and/or haemoglobin level, a low erythropoietin level (<=3·3 mUI/ml) and JAK2 mutation showed comparable positive predictive value (PPV) for true polycythemia (RCM>=125%), 92·1% and 90% respectively. A very‐low erythropoietin level (<=1·99 mUI/ml) had a PPV of 100% for polycythemia vera (PV) diagnosis. We confirmed the correlations between RCM, erythropoietin and JAK2 variant allelic frequency in PV patients. This study prompts the need to revisit the role of EPO in PV diagnostic criteria.
Disease Overview
Polycythemia vera (PV) is a JAK2‐mutated myeloproliferative neoplasm characterized by clonal erythrocytosis; other features include leukocytosis, thrombocytosis, splenomegaly, ...pruritus, constitutional symptoms, microcirculatory disturbances, and increased risk of thrombosis and progression into myelofibrosis (post‐PV MF) or acute myeloid leukemia (AML).
Diagnosis
A working diagnosis is considered in the presence of a JAK2 mutation associated with hemoglobin/hematocrit levels of >16.5 g/dL/49% in men or 16 g/dL/48% in women; morphologic confirmation by bone marrow examination is advised but not mandated.
Cytogenetics
Abnormal karyotype is seen in 15%–20% of patients with the most frequent sole abnormalities being +9 (5%), loss of chromosome Y (4%), +8 (3%), and 20q− (3%).
Mutations
Over 50% of patients harbor DNA sequence variants/mutations other than JAK2, with the most frequent being TET2 (18%) and ASXL1 (15%). Prognostically adverse mutations include SRSF2, IDH2, RUNX1, and U2AF1, with a combined incidence of 5%–10%.
Survival and Prognosis
Median survival is ⁓15 years but exceeds 35 years for patients aged ≤40 years. Risk factors for survival include older age, leukocytosis, abnormal karyotype, and the presence of adverse mutations. Twenty‐year risk for thrombosis, post‐PV MF, or AML are ⁓26%, 16% and 4%, respectively.
Risk Factors for Thrombosis
Two risk categories are considered: high (age >60 years or thrombosis history) and low (absence of both risk factors). Additional predictors for arterial thrombosis include cardiovascular risk factors and for venous thrombosis higher absolute neutrophil count and JAK2V617F allele burden.
Treatment
Current goal of therapy is to prevent thrombosis. Periodic phlebotomy, with a hematocrit target of <45%, combined with once‐ or twice‐daily aspirin (81 mg) therapy, absent contraindications, is the backbone of treatment in all patients, regardless of risk category. Cytoreductive therapy is reserved for high‐risk disease with first‐line drugs of choice being hydroxyurea and pegylated interferon‐α and second‐line busulfan and ruxolitinib. In addition, systemic anticoagulation is advised in patients with venous thrombosis history.
Additional Treatment Considerations
At the present time, we do not consider a drug‐induced reduction in JAK2V617F allele burden, which is often incomplete and seen not only with peg‐IFN but also with ruxolitinib and busulfan, as an indicator of disease‐modifying activity, unless accompanied by cytogenetic and independently‐verified morphologic remission. Accordingly, we do not use the specific parameter to influence treatment choices. The current review also includes specific treatment strategies in the context of pregnancy, splanchnic vein thrombosis, pruritus, perioperative care, and post‐PV MF.
Since its approval in 2011, the Janus kinase 1/2 (JAK1/2) inhibitor ruxolitinib has evolved to become the centerpiece of therapy for myelofibrosis (MF), and its use in patients with hydroxyurea ...resistant or intolerant polycythemia vera (PV) is steadily increasing. Several other JAK2 inhibitors have entered clinical testing, but none have been approved and many have been discontinued. Importantly, the activity of these agents is not restricted to patients with JAK2 V617F or exon 12 mutations. Although JAK2 inhibitors provide substantial clinical benefit, their disease-modifying activity is limited, and rational combinations with other targeted agents are needed, particularly in MF, in which survival is short. Many such combinations are being explored, as are other novel agents, some of which could successfully be combined with JAK2 inhibitors in the future. In addition, new JAK2 inhibitors with the potential for less myelosuppression continue to be investigated. Given the proven safety and efficacy of ruxolitinib, it is likely that ruxolitinib-based combinations will be a major way forward in drug development for MF. If approved, less myelosuppressive JAK2 inhibitors such as pacritinib or NS-018 could prove to be very useful additions to the therapeutic armamentarium in MF. In PV, inhibitors of histone deacetylases and human double minute 2 have activity, but their role, if any, in the future treatment algorithm is uncertain, given the availability of ruxolitinib and renewed interest in interferons. Ruxolitinib is in late-phase clinical trials in essential thrombocythemia, in which it could fill an important void for patients with troublesome symptoms.
Polycythemia vera (PV) is characterized by JAK/STAT activation, thrombotic/hemorrhagic events, systemic symptoms, and disease transformation. In high-risk PV, ruxolitinib controls blood counts and ...improves symptoms.
MAJIC-PV is a randomized phase II trial of ruxolitinib versus best available therapy (BAT) in patients resistant/intolerant to hydroxycarbamide (HC-INT/RES). Primary outcome was complete response (CR) within 1 year. Secondary outcomes included duration of response, event-free survival (EFS), symptom, and molecular response.
One hundred eighty patients were randomly assigned. CR was achieved in 40 (43%) patients on ruxolitinib versus 23 (26%) on BAT (odds ratio, 2.12; 90% CI, 1.25 to 3.60;
= .02). Duration of CR was superior for ruxolitinib (hazard ratio HR, 0.38; 95% CI, 0.24 to 0.61;
< .001). Symptom responses were better with ruxolitinib and durable. EFS (major thrombosis, hemorrhage, transformation, and death) was superior for patients attaining CR within 1 year (HR, 0.41; 95% CI, 0.21 to 0.78;
= .01); and those on ruxolitinib (HR, 0.58; 95% CI, 0.35 to 0.94;
= .03). Serial analysis of
V617F variant allele fraction revealed molecular response was more frequent with ruxolitinib and was associated with improved outcomes (progression-free survival PFS
= .001, EFS
= .001, overall survival
= .01) and clearance of
V617F stem/progenitor cells.
1 mutations predicted for adverse EFS (HR, 3.02; 95% CI, 1.47 to 6.17;
= .003). The safety profile of ruxolitinib was as previously reported.
The MAJIC-PV study demonstrates ruxolitinib treatment benefits HC-INT/RES PV patients with superior CR, and EFS as well as molecular response; importantly also demonstrating for the first time, to our knowledge, that molecular response is linked to EFS, PFS, and OS.
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