Concept: Polycythemia vera
Background Current treatment recommendations for patients with polycythemia vera call for maintaining a hematocrit of less than 45%, but this therapeutic strategy has not been tested in a randomized clinical trial. Methods We randomly assigned 365 adults with JAK2-positive polycythemia vera who were being treated with phlebotomy, hydroxyurea, or both to receive either more intensive treatment (target hematocrit, <45%) (low-hematocrit group) or less intensive treatment (target hematocrit, 45 to 50%) (high-hematocrit group). The primary composite end point was the time until death from cardiovascular causes or major thrombotic events. The secondary end points were cardiovascular events, cardiovascular hospitalizations, incidence of cancer, progression to myelofibrosis, myelodysplasia or leukemic transformation, and hemorrhage. An intention-to-treat analysis was performed. Results After a median follow-up of 31 months, the primary end point was recorded in 5 of 182 patients in the low-hematocrit group (2.7%) and 18 of 183 patients in the high-hematocrit group (9.8%) (hazard ratio in the high-hematocrit group, 3.91; 95% confidence interval [CI], 1.45 to 10.53; P=0.007). The primary end point plus superficial-vein thrombosis occurred in 4.4% of patients in the low-hematocrit group, as compared with 10.9% in the high-hematocrit group (hazard ratio, 2.69; 95% CI, 1.19 to 6.12; P=0.02). Progression to myelofibrosis, myelodysplasia or leukemic transformation, and bleeding were observed in 6, 2, and 2 patients, respectively, in the low-hematocrit group, as compared with 2, 1, and 5 patients, respectively, in the high-hematocrit group. There was no significant between-group difference in the rate of adverse events. Conclusions In patients with polycythemia vera, those with a hematocrit target of less than 45% had a significantly lower rate of cardiovascular death and major thrombosis than did those with a hematocrit target of 45 to 50%. (Funded by the Italian Medicines Agency and others; ClinicalTrials.gov number, NCT01645124 , and EudraCT number, 2007-006694-91 .).
Marchioli et al.(1) report in the Journal that a hematocrit target of less than 45% for therapeutic phlebotomy reduces the risk of thrombosis in patients with polycythemia vera. In the genomic era, readers may question attention given to a measurement as mundane as the hematocrit, but this study resolves a half-century of debate about the role of phlebotomy in polycythemia vera and has ramifications for diagnosis and management. Polycythemia vera is a unique myeloproliferative disorder in which there is overproduction of morphologically normal erythrocytes, granulocytes, and platelets, a phenotype that is caused by a mutation (V617F) in JAK2, encoding . . .
Symptomatic Profiles of Patients With Polycythemia Vera: Implications of Inadequately Controlled Disease
- Journal of clinical oncology : official journal of the American Society of Clinical Oncology
- Published over 2 years ago
Polycythemia vera (PV) is a myeloproliferative neoplasm (MPN) associated with disabling symptoms and a heightened risk of life-threatening complications. Recent studies have demonstrated the effectiveness of JAK inhibitor therapy in patients with PV patients who have a history of prior hydroxyurea (HU) use (including resistance or intolerance), phlebotomy requirements, and palpable splenomegaly. We aimed to determine how these features contribute alone and in aggregate to the PV symptom burden.
Ruxolitinib, a Janus kinase (JAK) 1 and 2 inhibitor, was shown to have a clinical benefit in patients with polycythemia vera in a phase 2 study. We conducted a phase 3 open-label study to evaluate the efficacy and safety of ruxolitinib versus standard therapy in patients with polycythemia vera who had an inadequate response to or had unacceptable side effects from hydroxyurea.
Recently reported mature survival data have confirmed the favorable prognosis in polycythemia vera (PV), with an estimated median survival of 24 years, in patients younger than age 60 years old. Currently available drugs for PV have not been shown to prolong survival or alter the natural history of the disease and are instead indicated primarily for prevention of thrombosis. Unfortunately, study endpoints that are being utilized in currently ongoing clinical trials in PV do not necessarily target clinically or biologically relevant outcomes, such as thrombosis, survival, or morphologic remission, and are instead focused on components of disease palliation. Even more discouraging has been the lack of critical appraisal from “opinion leaders”, on the added value of newly approved drugs. Keeping these issues in mind, at present, we continue to advocate conservative management in low-risk PV (phlebotomy combined with once- or twice-daily aspirin therapy) and include cytoreductive therapy in “high-risk” patients; in the latter regard, our first, second, and third line drugs of choice are hydroxyurea, pegylated interferon-α and busulfan, respectively. In addition, it is reasonable to consider JAK2 inhibitor therapy, in the presence of protracted pruritus or markedly enlarged splenomegaly shown to be refractory to the aforementioned drugs.
Current drug therapy for myeloproliferative neoplasms, including essential thrombocythemia (ET) and polycythemia vera (PV), is neither curative nor has it been shown to prolong survival. Fortunately, prognosis in ET and PV is relatively good, with median survivals in younger patients estimated at 33 and 24 years, respectively. Therefore, when it comes to treatment in ET or PV, less is more and one should avoid exposing patients to new drugs that have not been shown to be disease-modifying, and whose long-term consequences are suspect (e.g., ruxolitinib). Furthermore, the main indication for treatment in ET and PV is to prevent thrombosis and, in that regard, none of the newer drugs have been shown to be superior to the time-tested older drugs (e.g., hydroxyurea). We currently consider three major risk factors for thrombosis (history of thrombosis, JAK2/MPL mutations, and advanced age), in order to group ET patients into four risk categories: “very low risk” (absence of all three risk factors); “low risk” (presence of JAK2/MPL mutations); “intermediate-risk” (presence of advanced age); and “high-risk” (presence of thrombosis history or presence of both JAK2/MPL mutations and advanced age). Herein, we provide a point-of-care treatment algorithm that is risk-adapted and based on evidence and decades of experience.
Treatments for high-risk essential thrombocythemia (ET) address thrombocytosis, disease-related symptoms, as well as risks of thrombosis, hemorrhage, transformation to myelofibrosis and leukemia. Patients resistant/intolerant to hydroxycarbamide (HC) have a poor outlook. MAJIC (ISRCTN61925716) is a randomized phase II trial of ruxolitinib (JAK1/2 inhibitor) vs Best Available Therapy (BAT) in ET and polycythemia vera (PV) patients resistant or intolerant to HC. Here findings of MAJIC-ET are reported, where the modified intention-to-treat population included 58 & 52 patients randomized to receive ruxolitinib or BAT respectively. There was no evidence of improvement in complete response within 1 year reported in 27 (46.6%) patients treated with ruxolitinib vs 23 (44.2%) with BAT (P=.40). At 2 years rates of thrombosis, hemorrhage and transformation were not significantly different, however some disease-related symptoms improved in patients receiving ruxolitinib relative to BAT. Molecular responses were uncommon; there were two complete molecular responses (CMR) and one partial molecular response (PMR) in CALR positive ruxolitinib-treated patients. Transformation to myelofibrosis occurred in one CMR patient, presumably due to the emergence of a different clone raising questions about the relevance of CMR in ET patients. Grade 3&4 anemia occurred in 19% & 0% of ruxolitinib vs 0% (both grades) BAT arm, grade 3&4 thrombocytopenia in 5.2% & 1.7% of ruxolitinib vs 0% (both grades) of BAT treated patients. Rates of discontinuation or treatment switching did not differ between the two trial arms. The MAJIC-ET trial suggests that ruxolitinib is not superior to current second-line treatments for ET.
Polycythemia vera (PV), a clonal disorders of hematopoietic stem/progenitor cells that manifests with prevalent expansion of red cell mass, is the most frequent among chronic myeloproliferative neoplasms (MPN). It is characterized by a V617F point mutation in JAK2 exon 14 , or less common mutations in exon 12, in virtually all cases. The landmark discovery of autonomously activated JAK/STAT signaling pathway paved the way for the clinical development of the first target drug, the JAK1 and JAK2 inhibitor ruxolitinib, that is now approved for patients with resistance or intolerance to hydroxyurea. Phlebotomies and hydroxyurea are still the cornerstone of treatment, aimed to prevent the first appearance or recurrence of cardiovascular events that, together with progression to post-PV myelofibrosis and leukemia, represent the main cause of death. Interferon-alpha is an alternative drug, shown to induce molecular remissions; currently, it is undergoing phase 3 trials, that might eventually lead to its approval. The last few years have witnessed important advances for an accurate and precocious diagnosis of PV, the understanding of pathogenesis and for improved patient management. This review will focus on the most recent achievements, trying to unify the different concepts in a personalized approach to the patient with PV.
Myeloproliferative neoplasms (MPNs) include essential thrombocythemia, polycythemia vera (PV) and primary myelofibrosis (PMF). Phenotype-driver mutations of JAK2, CALR and MPL genes are present in MPNs and can be variably combined with additional mutations. Driver mutations entail a constitutive activation of the JAK2/STAT pathway, the key signaling cascade in MPNs. Among JAK2 inhibitors (JAKis), ruxolitinib (RUX) has been approved for the treatment of intermediate and high risk myelofibrosis (MF) and of PV inadequately controlled by or intolerant of hydroxyurea. Other JAKis, such as fedratinib, pacritinib proved to be useful in MF. The primary endpoints in MF trials were spleen volume response (SVR) and symptom response, whereas in PV trials they were hematocrit control with/without spleen response. In advanced MF, RUX achieved a SVR of more than 35% in around 60% of patients and is long lasting, establishing a new benchmark for MF treatment. RUX efficacy in early MF is also remarkable and toxicity is mild. In PV, hematocrit control was achieved with RUX in approximately 60% of the cases and SVR in 40%. Symptom relief was evident in both conditions. In the long term however, many MF patients lose their SVR. Indeed, the definition of RUX-failure and the design of new trials in this setting are unmet needs. Decrease of hemoglobin/platelet levels and increased infection rates are the most common side effects of RUX, and non-melanoma skin tumors need to be monitored while on treatment. In conclusion, the introduction of JAKis raises the bar of treatment goals in MF and PV.
Polycythemia vera (PV) is the most common myeloproliferative neoplasm (MPN), the ultimate phenotype of the JAK2 V1617F mutation, the MPN with the highest incidence of thromboembolic complications, which usually occur early in the course of the disease, and the only MPN in which erythrocytosis occurs. The classical presentation of PV is characterized by erythrocytosis, leukocytosis, and thrombocytosis, often with splenomegaly and occasionally with myelofibrosis, but it can also present as isolated erythrocytosis with or without splenomegaly, isolated thrombocytosis or isolated leukocytosis, or any combination of these. When PV is present, the peripheral blood hematocrit (or hemoglobin) determination will not accurately represent the actual volume of red cells in the body, because in PV, in contrast to other disorders causing erythrocytosis, when the red cell mass increases, the plasma volume usually increases. In fact, unless the hematocrit is greater than 59%, true erythrocytosis cannot be distinguished from pseudoerythrocytosis due to plasma volume contraction. Usually, the presence of splenomegaly or leukocytosis or thrombocytosis establishes the diagnosis. However, when a patient presents with isolated thrombocytosis and a positive JAK2 V617F assay, particularly a young woman, the possibility of PV must always be considered because of plasma volume expansion. The WHO PV diagnostic guidelines are not helpful in this situation, since the hematocrit is invariably normal and a bone marrow examination will not distinguish ET from PV. Only a direct measurement of both the red cell mass and plasma volume can establish the correct diagnosis. In managing a PV patient, it is important to remember that PV is an indolent disorder in which life span is usually measured in decades, even when myelofibrosis is present, that chemotherapy is futile in eradicating the disease but does increase the incidence of acute leukemia and that hydroxyurea is not safe in this regard nor is it antithrombotic. Phlebotomy to a sex-specific normal hematocrit is the cornerstone of therapy and there now exist safe remedies for controlling leukocytosis, thrombocytosis, and extramedullary hematopoiesis and symptoms due to inflammatory cytokines when this is necessary.