Therapeutic options for patients with polycythemia vera and essential thrombocythemia refractory/resistant to hydroxyurea

Therapeutics for sickle cell disease intravascular hemolysis

Sickle cell disease (SCD) is a genetic disorder predominantly affecting individuals of African descent, with a significant global health burden. SCD is characterized by intravascular hemolysis, driven by the polymerization of mutated hemoglobin within red blood cells (RBCs), leading to vascular inflammation, organ damage, and heme toxicity. Clinical manifestations include acute pain crises, hemolytic anemia, and multi-organ dysfunction, imposing substantial morbidity and mortality challenges. Current therapeutic strategies mitigate these complications by increasing the concentration of RBCs with normal hemoglobin via transfusion, inducing fetal hemoglobin, restoring nitric oxide signaling, inhibiting platelet-endothelium interaction, and stabilizing hemoglobin in its oxygenated state. While hydroxyurea and gene therapies show promise, each faces distinct challenges. Hydroxyurea's efficacy varies among patients, and gene therapies, though effective, are limited by issues of accessibility and affordability. An emerging frontier in SCD management involves harnessing endogenous clearance mechanisms for hemolysis products. A recent work by Heggland et al. showed that CD-36-like proteins mediate heme absorption in hematophagous ectoparasite, a type of parasite that feeds on the blood of its host. This discovery underscores the need for further investigation into scavenger receptors (e.g., CD36, SR-BI, SR-BII) for their possible role in heme uptake and detoxification in mammalian species. In this review, we discussed current SCD therapeutics and the specific stages of pathophysiology they target. We identified the limitations of existing treatments and explored potential future developments for novel SCD therapies. Novel therapeutic targets, including heme scavenging pathways, hold the potential for improving outcomes and reducing the global burden of SCD.

Relationship between amide ratio assessed by Fourier-transform infrared spectroscopy: A biomarker candidate for polycythemia vera disease

The study utilized Fourier transform infrared (FTIR) spectroscopy coupled with chemometrics to investigate protein composition and structural changes in the blood serum of patients with polycythemia vera (PV). Principal component analysis (PCA) revealed distinct biochemical properties, highlighting elevated absorbance of phospholipids, amides, and lipids in PV patients compared to healthy controls. Ratios of amide I/amide II and amide I/amide III indicated alterations in protein structures. Support vector machine analysis and receiver operating characteristic curves identified amide I as a crucial predictor of PV, achieving 100% accuracy, sensitivity, and specificity, while amide III showed a lower predictive value (70%). PCA analysis demonstrated effective differentiation between PV patients and controls, with key wavenumbers including amide II, amide I, and CH lipid vibrations. These findings underscore the potential of FTIR spectroscopy for diagnosing and monitoring PV.

Long-acting interferon: pioneering disease modification of myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are clonal disorders of hematopoietic stem cells. The malignant clones produce cytokines that drive self-perpetuating inflammatory responses and tend to transform into more aggressive clones, leading to disease progression. The progression of MPNs follows a biological sequence from the early phases of malignancy, polycythemia vera, and essential thrombocythemia, to advanced myelofibrosis and leukemic transformation. To date, the treatment of MPNs has focused on preventing thrombosis by decreasing blood cell counts and relieving disease-related symptoms. However, interferon (IFN) has been used to treat MPNs because of its ability to attack cancer cells directly and modulate the immune system. IFN also has the potential to modulate diseases by inhibiting JAK2 mutations, and recent studies have demonstrated clinical and molecular improvements. Long-acting IFN is administered less frequently and has fewer adverse effects than conventional IFN. The current state of research on long-acting IFN in patients with MPNs is discussed, along with future directions.

A phase II trial to assess the efficacy and safety of ropeginterferon α-2b in Chinese patients with polycythemia vera

Ropeginterferon α-2b is a mono-PEGylated proline-interferon for the treatment of polycythemia vera (PV). This drug is used biweekly with a starting dose of 100 μg (50 μg if patients receiving hydroxyurea) and 50 μg increments up to a maximum dose of 500 μg. Increasing evidence indicates that patients can tolerate higher starting doses of ropeginterferon α-2b. This phase II trial utilizes 250 μg as the starting dose, 350 μg at week 2 and 500 μg at week 4 as the target dose. Doses can be adjusted according to tolerability. This study assesses the safety, efficacy and molecular response of ropeginterferon α-2b in Chinese patients with PV utilizing the 250-350-500 μg dosing schema. This study will be used to support the application of a biologics license for PV treatment in China.

SURPASS-ET: phase III study of ropeginterferon alfa-2b versus anagrelide as second-line therapy in essential thrombocythemia

Patients diagnosed with high-risk essential thrombocythemia (ET) have limited treatment options to reduce the risk of thrombosis and lessen the progression of the disease by targeting the molecular source. Hydroxyurea is the recommended treatment, but many patients experience resistance or intolerance. Anagrelide is an approved second-line option for ET, but concerns of a higher frequency of disease transformation may affect its role as a suitable long-term option. Interferons have been evaluated in myeloproliferative neoplasms for over 30 years, but early formulations had safety and tolerability issues. SURPASS-ET (NCT04285086) is a phase III, open-label, multicenter, global, randomized, active-controlled trial that will evaluate the safety, efficacy, tolerability and pharmacokinetics of ropeginterferon alfa-2b compared with anagrelide as second-line therapy in high-risk ET.

The MDM2 antagonist idasanutlin in patients with polycythemia vera: results from a single-arm phase 2 study

Idasanutlin, an MDM2 antagonist, showed clinical activity and a rapid reduction in JAK2 V617F allele burden in patients with polycythemia vera (PV) in a phase 1 study. This open-label phase 2 study evaluated idasanutlin in patients with hydroxyurea (HU)-resistant/-intolerant PV, per the European LeukemiaNet criteria, and phlebotomy dependence; prior ruxolitinib exposure was permitted. Idasanutlin was administered once daily on days 1 through 5 of each 28-day cycle. The primary end point was composite response (hematocrit control and spleen volume reduction > 35%) in patients with splenomegaly and hematocrit control in patients without splenomegaly at week 32. Key secondary end points included safety, complete hematologic response (CHR), patient-reported outcomes, and molecular responses. All patients (n = 27) received idasanutlin; 16 had response assessment (week 32). Among responders with baseline splenomegaly (n = 13), 9 (69%) attained any spleen volume reduction, and 1 achieved composite response. Nine patients (56%) achieved hematocrit control, and 8 patients (50%) achieved CHR. Overall, 43% of evaluable patients (6/14) showed a ≥50% reduction in the Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (week 32). Nausea (93%), diarrhea (78%), and vomiting (41%) were the most common adverse events, with grade ≥ 3 nausea or vomiting experienced by 3 patients (11%) and 1 patient (4%), respectively. Reduced JAK2 V617F allele burden occurred early (after 3 cycles), with a median reduction of 76%, and was associated with achieving CHR and hematocrit control. Overall, the idasanutlin dosing regimen showed clinical activity and rapidly reduced JAK2 allele burden in patients with HU-resistant/- intolerant PV but was associated with low-grade gastrointestinal toxicity, leading to poor long-term tolerability. This trial was registered at www.clinincaltrials.gov as #NCT03287245.

Transformation of Polycythemia Vera to Pure Erythroid Leukemia

Pure erythroid leukemia (PEL) is an aggressive and exceedingly rare form of acute leukemia characterized as a neoplastic proliferation of immature cells committed to the erythroid lineage. It has a poor overall median survival of two to three months. To our knowledge, there are currently only a handful of reports of PEL arising from polycythemia vera. Most reported cases have been associated with radiation therapy or chemotherapeutic alkylating agents. Here we report a rare occurrence of polycythemia vera treated with phlebotomy and hydroxyurea that underwent leukemic transformation to pure erythroid leukemia.

Immunotherapy and Immunomodulation in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are characterized by chronic inflammation. The discovery of constitutively active JAK-STAT signaling associated with driver mutations has led to clinical and translational breakthroughs. Insights into the other pathways and novel factors of potential importance are being actively investigated. Various classes of agents with immunomodulating or immunosuppressive properties have been used with varying degrees of success in treating myeloproliferative neoplasms. Early clinical trials are investigating the feasibility, effectiveness, and safety of immune checkpoint inhibitors, cell-based immunotherapies, and SMAC mimetics. The dynamic landscape of immunotherapy and immunomodulation in myeloproliferative neoplasms is the topic of the present review.

Thromboembolic events in polycythemia vera

Thromboembolic events and cardiovascular disease are the most prevalent complications in patients with polycythemia vera (PV) compared with other myeloproliferative disorders and are the major cause of morbidity and mortality in this population. Moreover, a vascular complication such as arterial or venous thrombosis often leads to the diagnosis of PV. The highest rates of thrombosis typically occur shortly before or at diagnosis and decrease over time, probably due to the effects of treatment. Important risk factors include age (≥ 60 years old) and a history of thrombosis; elevated hematocrit and leukocytosis are also associated with an increased risk of thrombosis. The goal of therapy is to reduce the risk of thrombosis by controlling hematocrit to < 45%, a target associated with reduced rates of cardiovascular death and major thrombosis. Low-risk patients (< 60 years old with no history of thrombosis) are managed with phlebotomy and low-dose aspirin, whereas high-risk patients (≥ 60 years old and/or with a history of thrombosis) should be treated with cytoreductive agents. Interferon and ruxolitinib are considered second-line therapies for patients who are intolerant of or have an inadequate response to hydroxyurea, which is typically used as first-line therapy. In this review, we discuss factors associated with thrombosis and recent data on current treatments, including anticoagulation, highlighting the need for more controlled studies to determine the most effective cytoreductive therapies for reducing the risk of thrombosis in patients with PV.

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.

Ruxolitinib vs best available therapy for ET intolerant or resistant to hydroxycarbamide

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 2 trial of ruxolitinib (JAK1/2 inhibitor) vs best available therapy (BAT) in ET and polycythemia vera patients resistant or intolerant to HC. Here, findings of MAJIC-ET are reported, where the modified intention-to-treat population included 58 and 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 2 complete molecular responses (CMR) and 1 partial molecular response in CALR-positive ruxolitinib-treated patients. Transformation to myelofibrosis occurred in 1 CMR patient, presumably because of the emergence of a different clone, raising questions about the relevance of CMR in ET patients. Grade 3 and 4 anemia occurred in 19% and 0% of ruxolitinib vs 0% (both grades) in the BAT arm, and grade 3 and 4 thrombocytopenia in 5.2% and 1.7% of ruxolitinib vs 0% (both grades) of BAT-treated patients. Rates of discontinuation or treatment switching did not differ between the 2 trial arms. The MAJIC-ET trial suggests that ruxolitinib is not superior to current second-line treatments for ET. This trial was registered at www.isrctn.com as #ISRCTN61925716.

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.

Patterns of hydroxyurea use and clinical outcomes among patients with polycythemia vera in real-world clinical practice: a chart review

BACKGROUND

Hydroxyurea (HU) is among the most commonly used cytoreductive treatments for polycythemia vera (PV), but previous research and clinical experience suggest that not all patients respond optimally, consistently, or durably to HU treatment. This study investigated patterns of HU use and impact on disease control among patients with PV in real-world clinical practice in the United States.

METHODS

Oncologists and hematologists recruited between April and July 2014 reported data from patient charts. Treatment history and disease symptom comparisons between HU subgroups were performed using Chi square tests or one-way analyses of variance for categorical and continuous variables. Other analyses were performed using descriptive statistics.

RESULTS

Overall, 329 physicians participated and provided data on 1309 patients with PV (62.3 % male; mean age = 62.5 years, mean time since diagnosis = 5.2 years). In the 229 (17.5 %) patients who had stopped HU, the most common reasons for HU discontinuation-as assessed by the treating clinician-were inadequate response (29.3 %), intolerance (27.5 %), and disease progression (12.7 %). Among patients currently on HU, a significant proportion had elevated blood cell counts: 34.4 % had hematocrit values ≥45 %, 59.4 % had platelet levels >400 × 10(9)/L, and 58.2 % had WBC counts > 10 × 10(9)/L. Two-thirds (66.3 %) of patients had ≥1 elevated count, 40.3 % had ≥2 elevated counts, and 19.8 % had all 3 counts elevated. The most common PV-related signs and symptoms among all patients were fatigue and splenomegaly.

CONCLUSIONS

Although many patients with PV benefit from HU therapy, some continue to have suboptimal control of their disease, as evidenced by persistence of abnormally elevated blood cell counts and the continued experience of disease-related manifestations (signs and symptoms). These data further denote a significant medical need for some patients with PV currently or previously treated with HU.

Management of side effects of BCR/ABL-negative chronic myeloproliferative neoplasm therapies. Focus on anagrelide

Although hydroxyurea is considered the first-line cytoreductive therapy in high-risk patients with polycythemia vera or essential thrombocythemia, approximately 20-25% of patients develop resistance or intolerance and they need an alternative therapy. Anagrelide is the treatment of choice in patients with essential thrombocythemia intolerant or with resistance to hydroxyurea. Anagrelide is usually well tolerated. Although there is concern about the increased risk of cardiac side effects, in most cases these are mild, and easily manageable. In this paper, the available evidence about the management of patients with myeloproliferative neoplasms, with a special focus on the side effects of drug therapies is reviewed.

Current and future treatment options for polycythemia vera

Patients with polycythemia vera (PV), a myeloproliferative neoplasm characterized by an elevated red blood cell mass, are at high risk of vascular and thrombotic complications and have reduced quality of life due to a substantial symptom burden that includes pruritus, fatigue, constitutional symptoms, microvascular disturbances, and bleeding. Conventional therapeutic options aim at reducing vascular and thrombotic risk, with low-dose aspirin and phlebotomy as first-line recommendations for patients at low risk of thrombotic events and cytoreductive therapy (usually hydroxyurea or interferon alpha) recommended for high-risk patients. However, long-term effective and well-tolerated treatments are still lacking. The discovery of mutations in Janus kinase 2 (JAK2) as the underlying molecular basis of PV has led to the development of several targeted therapies, including JAK inhibitors, and results from the first phase 3 clinical trial with a JAK inhibitor in PV are now available. Here, we review the current treatment landscape in PV, as well as therapies currently in development.

Ruxolitinib versus standard therapy for the treatment of polycythemia vera

BACKGROUND

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.

METHODS

We randomly assigned phlebotomy-dependent patients with splenomegaly, in a 1:1 ratio, to receive ruxolitinib (110 patients) or standard therapy (112 patients). The primary end point was both hematocrit control through week 32 and at least a 35% reduction in spleen volume at week 32, as assessed by means of imaging.

RESULTS

The primary end point was achieved in 21% of the patients in the ruxolitinib group versus 1% of those in the standard-therapy group (P<0.001). Hematocrit control was achieved in 60% of patients receiving ruxolitinib and 20% of those receiving standard therapy; 38% and 1% of patients in the two groups, respectively, had at least a 35% reduction in spleen volume. A complete hematologic remission was achieved in 24% of patients in the ruxolitinib group and 9% of those in the standard-therapy group (P=0.003); 49% versus 5% had at least a 50% reduction in the total symptom score at week 32. In the ruxolitinib group, grade 3 or 4 anemia occurred in 2% of patients, and grade 3 or 4 thrombocytopenia occurred in 5%; the corresponding percentages in the standard-therapy group were 0% and 4%. Herpes zoster infection was reported in 6% of patients in the ruxolitinib group and 0% of those in the standard-therapy group (grade 1 or 2 in all cases). Thromboembolic events occurred in one patient receiving ruxolitinib and in six patients receiving standard therapy.

CONCLUSIONS

In patients who had an inadequate response to or had unacceptable side effects from hydroxyurea, ruxolitinib was superior to standard therapy in controlling the hematocrit, reducing the spleen volume, and improving symptoms associated with polycythemia vera. (Funded by Incyte and others; RESPONSE ClinicalTrials.gov number, NCT01243944.).

Polycythemia Vera Diagnosed after Esophageal Variceal Rupture

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm that leads to hyperviscosity and the risk of thrombosis. We encountered the case of a young male Filipino patient diagnosed with PV after the rupture of esophageal varices. The complete blood cell count showed a slight increase in white blood cells. An abdominal computed tomography scan disclosed splenomegaly and occlusion of the portal vein and collateral vessels. A blood examination demonstrated an increase in all three blood cell lines within three months. Based on the presence of severe hypercellularity of the bone marrow and positivity for the JAK2V617F mutation, we finally diagnosed the patient with PV.