Cardiovascular Risk in Philadelphia-Negative Myeloproliferative Neoplasms: Mechanisms and Implications—A Narrative Review

by Samuel Bogdan TodorCristian IchimAdrian Boicean, and Romeo Gabriel Mihaila

Abstract

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

Ropeginterferon alfa-2b shows anti-polycythaemia vera activity without causing clinically significant anaemia

Keita Kirito, Albert Qin, Shanshan Suo, Rongfeng Fu, Daoxiang Wu, Toshiaki Sato, Oleh Zagrijtschuk, Kazuya Shimoda, Norio Komatsu & Jie Jin

July 11, 2o24

Polycythaemia vera (PV) is a Philadelphia chromosome-negative myeloproliferative neoplasm (MPN) that, in most cases, harbour the Janus kinase 2 gene (JAK2) driver mutation JAK2V617F [1]. PV is characterised by an over-production of blood cells with increased haematocrit levels, which is a risk factor for thrombotic events (TEs) and cardiovascular mortality [12]. Low-dose aspirin and phlebotomy are usually recommended for patients with low-risk PV (i.e., no history of thrombosis and age ≤60 years). The National Comprehensive Cancer Network (NCCN) recommends ropeginterferon alfa-2b (BESREMi®) as a preferred cytoreductive treatment for patients with low- or high-risk PV [3].

Ropeginterferon alfa-2b is a novel polyethylene glycol (PEG)-conjugated recombinant proline-interferon alpha (IFN-a) with a favourable in vivo pharmacokinetic (PK) profile [45]. Ropeginterferon alfa-2b has demonstrated substantial anti-PV clinical activity, including complete haematologic response (CHR; defined as a haematocrit <45% without phlebotomy, a platelet count ≤ 400 × 109/L, and a white blood cell count ≤10 × 109/L) and a reduction in the JAK2V617F allele burden [6,7,8,9]. Ropeginterferon alfa-2b injection is approved for adult patients with PV at an initial dose of 100 µg (or 50 µg for patients already receiving cytoreductive therapy) with 50 µg incremental intrapatient increases in the dose up to a maximum recommended dose of 500 µg every two weeks. It can take several months to reach the plateau dose level [6]. An alternative dosing regimen with a higher starting dose of 250 µg and simpler intrapatient dose escalation to 500 µg every two weeks with flexible dose adjustment according to tolerability was explored as a treatment option. This regimen controlled PV effectively, as defined by the CHR, and was associated with a shorter time to achieve a CHR [89]. In this report, we aimed to examine the data from the approved slow-dose titration and exploratory higher starting dose regimens focusing on the dynamics of haemoglobin (Hgb) and the occurrence of anaemia. Anaemia is important in the context of PV treatment for several reasons. First, patients who undergo frequent phlebotomy may suffer from symptomatic iron deficiency, leading to anaemia [10]. Anaemia and symptoms can negatively affect the patient well-being and should be avoided in patients with PV and MPNs. The symptoms include headache, insomnia, concentration difficulties, dizziness, restless legs and may coincide and potentiate the disease-related symptoms of the underlying MPN [11,12,13]. Commonly used agents in the PV treatment cause anaemia in substantial numbers of cases ranging from 18% with hydroxyurea (HU) [14] to 72% with ruxolitinib [1115]. Anaemia is symptomatic in many cases and may limit the treatment dose or lead to treatment interruption if uncontrolled or severe cases are present. Association between venous thromboembolism and iron-deficiency anaemia has also been shown [16]. Thus, having an agent that can effectively control the elevated haematocrit without excessively suppressing the normal erythropoiesis is a major therapeutic advantage.

An important question regarding ropeginterferon alfa-2b in this context is whether the control of haematocrit is commonly accompanied by clinically significant anaemia, i.e., at the ≥grade 3 level or at the moderate, grade 2 level, but the anaemia is persistent and unmanageable. We therefore performed a retrospective analysis of the effect of ropeginterferon alfa-2b on Hgb levels at various time points or on the occurrence of anaemia with the data available from our two prospective clinical studies in patients with PV.

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Disease Duration, Elevated WBC Count, and VAF Predict Disease Progression in Polycythemia Vera

June 14, 2024

Author(s): Megan Hollasch

Time from diagnosis to enrollment, elevated white blood cell (WBC) count, and variant allele frequency (VAF) were significantly associated with an increased risk of disease progression among patients with polycythemia vera (PV), according to data from the phase 4 prospective, observational REVEAL study (NCT02252159) presented at the 2024 EHA Congress by Michael R. Grunwald, MD.

“Five predictors of PV progression were identified: disease duration, thrombotic event [TE] history, WBC count of greater than 11 × 109/L, hematocrit [HCT] level of 0.45 L/L or lower, and VAF. However, HCT [level] of 0.45 L/L or lower may be confounded by disease duration and cytoreductive treatment covariates. These results provide additional support for the use of disease duration and elevated WBC and VAF as risk factors for disease progression, and identify history of TEs as a potential novel risk factor,” Grunwald and coauthors wrote in a poster presentation of the findings. Grunwald is chief of the Leukemia Division at Atrium Health’s Levine Cancer Institute and director of the Transplantation and Cellular Therapy Program at Levine Cancer Institute in Charlotte, North Carolina.

At a median follow-up of 3.7 years, findings from REVEAL, the largest prospective, observational clinical study in patients with PV to date (n = 2023), showed that 6.7% of patients progressed to myelofibrosis (MF). Results from a univariate analysis of patients with vs without progression revealed that significant covariates consisted of time from PV diagnosis to enrollment (OR, 1.065; 95% CI, 1.040-1.090; P < .0001), history of TEs (yes vs no; OR, 1.722; 95% CI, 1.170-2.534; P = .0059), HCT levels of 0.45 L/L or lower (>0.45 vs ≤0.45 L/L; OR, 0.593; 95% CI, 0.410-0.858; P = .0056), and white blood cell (WBC) count of greater than 11 × 109/L at enrollment (>11 vs ≤11 × 109/L; OR, 2.053; 95% CI, 1.445-2.918; P < .0001).

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Pooled Analysis Shows Cytoreduction to Be Safe, Tolerable in Younger Patients With PV

Ashling Wahner

Cytoreductive therapy with interferon alfa (rIFNα) or hydroxyurea is safe and well tolerated in patients with polycythemia vera (PV) under the age of 60 years and induces annualized discontinuation rates comparable to those reported with these agents in older patients with PV, for whom cytoreductive therapy is routinely used, according to findings from a meta-analysis that were published in Blood Advances.1

Across the 14 studies included in this analysis, rIFNα discontinuation rates ranged from 4.6% to 37% over median durations of 0.4 to 6.3 years. Hydroxyurea discontinuation rates ranged from 2.6% to 17% over median durations of 0.5 to 14 years.

Although the use of cytoreductive agents, such as rIFNα and hydroxyurea, is associated with reduced thrombosis risk in PV, these agents are not routinely recommended by the European LeukemiaNet (ELN) or the National Comprehensive Cancer Network (NCCN) for patients with PV under the age of 60 years. The ELN recommends cytoreductive therapy for patients with PV who are younger than 60 years of age and have not had prior thrombotic events provided that they have strictly defined phlebotomy intolerance, symptomatic progressive splenomegaly, persistent or progressive leukocytosis, extreme thrombocytosis, persistently high cardiovascular risk, inadequate hematocrit control requiring phlebotomies, and/or persistently high symptom burden.2 The NCCN does not recommend cytoreductive therapy as initial treatment for patients with low-risk disease.3

“Unfortunately, effective and potentially life-prolonging cytoreductive therapy is often deferred in younger patients who are considered ‘low-risk’ because of their age and lack of thrombosis history,” senior study author Ghaith Abu-Zeinah, MD, an instructor in medicine at Weill Cornell Medical College and an assistant attending physician at the NewYork Presbyterian Hospital in New York, New York, and coauthors, wrote in the paper.1 “The rationale for withholding cytoreductive therapy is data-sparse and driven by theoretical concerns for toxicity and unknown benefits from early treatment. Yet, there is some evidence that early treatment is both well tolerated and potentially useful.”

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Dr Raajit Rampal Discusses Disease Modification and Emerging Therapies in Polycythemia Vera

Laura Joszt, MA

Achieving a disease-modifying therapy for polycythemia vera might require adjusting the end points in a study needed for a drug to be approved, said Raajit Rampal, MD, PhD, hematologic oncologist, associate attending physician, Memorial Sloan Kettering Cancer Center.

Transcript

Currently, there are no disease-modifying treatments in polycythemia vera, but it is being explored. What might such a therapy look like?

If we talk about disease modification, the first question is, what do you mean by disease modification? I think, what we would want is for our patients to live the longest and fullest life, free of the symptoms or burdens of their disease. To me, that is the sort of working definition of disease modification. From there, one can try to come up with biological definitions of things like depleting the stem cell, which are important things. But keeping this on a patient level, what we want for our patients [is a life free of disease burden]. How do we think about therapies that address those issues?

Part of it is a regulatory conundrum in the sense that studies have to meet certain end points for drugs to get approved, but the way we study the drugs is relative to the definitions of the end points that make the drugs successful. In many cases, [the end point is asking] are you controlling the hematocrit adequately? That’s one of the major things in polycythemia vera. But in order to really try to get at the question of disease modification, we’ve got to think about changing the end points of our studies to reflect that.

What are the things that are going to best correlate with the idea that you aren’t keeping patients free of the catastrophic consequences of their disease, like blood clots, like [disease] turning into leukemia or myelofibrosis? Are you controlling the patient’s symptoms to an adequate degree? Those are the things that I think are fundamental. But we’ve got to change the end points of our studies to really get at that.

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Younger Patients With PV May Benefit From Earlier Treatment With Cytoreductive Therapies

Laura Joszt, MA

Although patients younger than age 60 with polycythemia vera (PV) are typically not treated with cytoreductive therapy due to treatment toxicity concerns, this may result in an undertreatment of patients as there is no clear evidence that the risk of toxicity exceeds the potential benefit of treatment, according to a study published in Blood Advances.1

PV causes an overproduction of blood cells in the bone marrow, which leads to high numbers of circulating red blood cells.2 This thickens the blood, which may not flow through smaller blood vessels properly. Although PV can be diagnosed at any age, it most often occurs in people over the age of 60 years.2

For most patients, phlebotomy is the standard treatment, and it may be the only treatment needed for years. However, additional treatment to suppress the formation of blood cells in the bone marrow may be needed. Cytoreductive therapies, such as interferons, hydroxyurea, ruxolitinib, and anagrelide, may be needed, particularly for high-risk patients.3

Currently, cytoreductive therapies are not routinely recommended by the European LeukemiaNet or National Comprehensive Cancer Network for patients with PV younger than 60 years who don’t have a history of thrombosis, a high symptom burden, or an intolerance to phlebotomy.

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Rusfertide Treatment Strengthens Response and Decreases Erythrocytosis Among Patients With Polycythemia Vera

Jordan Kadish

03/22/2024

According to findings from the international phase 2 REVIVE trial published in The New England Journal of Medicine, treatment with rusfertide, a peptide mimetic of the master iron regulatory hormone hepcidin, strengthened responses and decreased erythrocytosis among patients with polycythemia vera (PV). Patients who received rusfertide demonstrated a mean hematocrit of less than 45% during the dose-finding period.

Marina Kremyanskaya, MD, PhD, Icahn School of Medicine at Mount Sinai, New York, New York, and coauthors stated, “Polycythemia vera is a chronic myeloproliferative neoplasm characterized by erythrocytosis,” or a high concentration of red blood cells in the blood. “The safety and efficacy of rusfertide in patients with phlebotomy-dependent polycythemia vera are unknown,” they added.

To expand on the available research, the study authors aimed to assess the efficacy of rusfertide among patients with polycythemia vera. The primary end point was a response, which was characterized by the hematocrit control, absence of phlebotomy, and finishing the trial regimen during part 2. The modified Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) patient diary was utilized to assess patient-reported outcomes of symptoms.

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