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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Serum Albumin Levels May Predict Survival Among Patients With Myelofibrosis Treated With Ruxolitinib

Serum albumin may function as a dynamic surrogate marker for clinical outcomes among patients with myelofibrosis treated with ruxolitinib, according to research published in JCO Precision Oncology. The utility of this surrogate measure may, however, vary by a given patient’s treatment status.

Previous work has established ruxolitinib, a JAK inhibitor, as a standard of care among patients with myelofibrosis. Yet although this treatment may help to reduce spleen size and symptom burden, it is unclear whether it improves overall survival (OS) rates.

New models, such as the RR6 model, have aimed to provide a prognostic surrogate measure for OS, though whether these models effectively distinguish high-risk disease from cases where there is no response to treatment is unclear. For this study, researchers aimed to evaluate whether serum albumin — which is linked with an anti-inflammatory response to treatment — is an effective surrogate marker for OS among patients with myelofibrosis.

Overall, data from 396 patients were included. In the cohort, among evaluable patients, 91 had received ruxolitinib while 305 were naïve to treatment, 58% of patients were male sex, and 72% of patients had primary myelofibrosis.

Analysis suggested that serum albumin levels frequently dropped among all patients, though this was less pronounced among patients treated with ruxolitinib. Relatedly, patients with a high serum albumin level at baseline had improved median OS periods (53.5 months) compared to patients with low levels (29.8 months; odds ratio, 1.95; <.001).

The link between serum albumin levels and OS was independent of variables included in the dynamic international prognostic scoring system, though only among patients who were naïve to ruxolitinib.

Future efforts to incorporate serum albumin with other inflammatory markers into an inflammatory index and assess its relevance in the context of other JAK inhibitors and combinations are ongoing.

Furthermore, among patients treated with ruxolitinib, changes in serum albumin levels predicted OS. Among patients with stable levels or an increase, median OS was 82.7 months, compared with 64.1 months among patients with a decrease (=.04).

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Genetics and Genetic Testing to Inform Myelofibrosis Clinical Management

by Charles Bankhead, Senior Editor, MedPage Today 

The history of primary myelofibrosis dates back to 1951 and the description of four distinct clinicopathologic entitiesopens in a new tab or window that came to be known as myeloproliferative neoplasms (MPNs): chronic myeloid leukemia (CML), polycythemia vera, essential thrombocythemia, and myelofibrosis.

Discovery of the Philadelphia (Ph) chromosome in 1960opens in a new tab or window paved the way to identification of BCR/ABL as the principal genetic driver of CML. Another 45 years passed before the discovery of a first genetic driver of non-Ph MPNs, a mutation in the Janus kinase 2 (JAK2) gene,opens in a new tab or window which occurs in 50-60% of myelofibrosis cases.

“The identification of that particular pathway was foundational, and it has changed the face of how we treat patients,” said James Rossetti, DO, of the University of Pittsburgh. “The JAK2 mutation is not present in everyone with myelofibrosis, and there are other mutations as well.”

Researchers identified a third key driver in 2013opens in a new tab or window: calreticulin gene (CALR). The mutation is associated with about 25% of myelofibrosis cases.

Most studies have shown that JAK2MPL, and CALR are mutually exclusiveopens in a new tab or window and do not occur together. However, a few studies have shown co-occurrence of the three key mutations. Even though JAK2MPL, and CALR usually do not occur together, numerous other mutations have been identified in association with the three primary mutations. As many as 80% of patients with myelofibrosisopens in a new tab or window have one or more other mutations.

Historically, myelofibrosis treatment was palliative in nature, aimed at relieving specific symptoms. The discovery of the JAK2 driver mutation has transformed treatment. Since 2011 four JAK2 inhibitors have received FDA approval: ruxolitinib (Jakafi)opens in a new tab or window, fedratinibopens in a new tab or window (Inrebic), pacritinibopens in a new tab or window (Vonjo), and momelotinibopens in a new tab or window (Ojjaara). All four drugs demonstrated ability to reduce splenomegaly, a major clinical manifestation of myelofibrosis, as well as symptoms.

Some of the co-occurring mutations are targetable, creating interest in combination therapies that simultaneously target different signaling pathways, said Aaron Gerds, MD, of the Cleveland Clinic. One such combination was evaluated in a clinical trial that paired a JAK2 inhibitor with an IDH2 inhibitor.

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Direct and indirect costs for patients with myeloproliferative neoplasms

Abstract

Myeloproliferative neoplasms (MPNs) are associated with substantial healthcare resource use and productivity loss. This retrospective cohort analysis used disability leave and medical claims data to measure direct and indirect healthcare costs associated with MPNs. The analysis included 173 patients with myelofibrosis (MF), 4477 with polycythemia vera (PV), 6061 with essential thrombocythemia (ET), and matched controls (n = 519, n = 13,431, and n = 18,183, respectively). Total healthcare costs were significantly higher for cases versus controls in each cohort (mean cost difference: MF, $67,456; PV, $10,970; ET, $22,279). Cases were more likely than controls to take disability leave and incurred higher disability-related costs. Among subgroups with thrombotic events, direct and indirect costs were higher for cases versus controls. Thrombotic events substantially increased direct costs and disability leave for patients with PV or ET compared with the full PV or ET cohorts. These findings demonstrate increased economic burden for patients with MPNs.

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Lack of Mutations Associated With Favorable Prognosis in MPN-U

Laura Joszt, MA

Among patients with myeloproliferative neoplasm, unclassifiable (MPN-U), bone marrow blast and the Dynamic International Prognostic Scoring System (DIPSS) plus score can predict overall survival (OS), according to a study published in American Journal of Clinical Pathology.1 In addition, the study found that the lack of certain mutations seemed to be associated with a better prognosis.

MPN-U is a type of MPN that doesn’t fit one of the other types of MPNs, such as chronic myelogenous leukemia (CML), myelofibrosis (MF), essential thrombocythemia (ET), or polycythemia vera (PV).2 Janus kinase (JAK) mutations are often present in PV, ET, and primary MF; MPL or CALR mutations are often present in ET and primary MF; and chromosome errors are present in patients with CML.2

This study identified additional potential poor prognostic markers for patients with MPN-U, which is important as MPN-U is a heterogeneous category with features that typically preclude classification. MPN-U cases show “a range of clinicopathologic presentations and differences in prognosis depending on the stage of disease,” the authors explained. “Creating further challenges, MPN-U cases remain relatively understudied.”

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Carotid Plaque Burden and Neutrophil-Lymphocyte Ratio in Patients with Philadelphia Negative Myeloproliferative Neoplasms and Their Relation to JAK2 V617F Mutation

Mahmoud Gaber, Mohamed Ezeldin, Mustafa Adel Younis, Moamen Abdelfadil Ismail, and Asmaa Ahmed Abdel-baset

 

Abstract

Background: Philadelphia negative myeloproliferative neoplasms are characterized by clonal myeloid cell proliferation. The JAK2V617F mutation may influence inflammation and atherosclerosis. Neutrophil-Lymphocyte Ratio and carotid plaque burden are markers associated with inflammation and cardiovascular risk, respectively.

This study aimed to investigate the relationship between NLR, carotid plaque burden, and JAK2V617F mutation in PN-MPN patients.

Patients and Methods: A retrospective case-control study included 90 PN-MPN patients and 60 controls. Data on demographics, comorbidities, thrombosis, laboratory parameters, carotid plaque burden, and JAK2V617F mutation status were collected.

Results: Age, gender distribution, smoking status, and comorbidities did not significantly differ between PN-MPN patients and controls. Thrombosis incidence in PN-MPN patients did not significantly differ from controls. Carotid plaque burden and NLR were significantly higher in PN-MPN patients compared to controls (p=0.024 and p<0.001, respectively). Majority of PN-MPN patients (78.9%) had positive JAK2V617F mutation status. NLR was significantly higher in PN-MPN patients with positive JAK2V617F mutation compared to negative (p=0.001). There was a significant difference in thrombosis incidence between patients with positive and negative JAK2V617F mutation status.

Conclusion: The study identified a significant link between higher N/L ratios and the JAK2V617F mutation in patients with PN-MPNs, proposing the N/L ratio as a potential marker for disease activity or mutation status. Despite observing a higher incidence of thrombosis in MPN patients and increased carotid plaque in PN-MPN patients compared to controls, no significant correlation was found between these cardiovascular risk markers and the JAK2V617F mutation status, suggesting other factors influence thrombosis risk in these patients.

Predictors of clinical outcome in myeloproliferative neoplasm, unclassifiable: A Bone Marrow Pathology Group study

Genevieve M Crane, MD, PhD; Julia T Geyer, MD; Beenu Thakral, MD; Sa A Wang, MD, Geoffrey D Wool, MD, PhD; Ke David Li, MD; Adam R Davis, MD; Leonardo Boiocchi, MD; David Bosler, MD; Carlos E Bueso-Ramos, MD, PhD

April 10, 2024

Abstract

Objectives

Myeloproliferative neoplasm, unclassifiable (MPN-U, revised to MPN, not otherwise specified in the fifth edition of the World Health Organization classification) is a heterogeneous category of primary marrow disorders with clinical, morphologic, and/or molecular features that preclude classification as a more specific MPN subtype due to stage at diagnosis, overlapping features between MPN subtypes, or the presence of coexisting disorders. Compared with other MPN subtypes, the contribution of the mutational landscape in MPN-U in conjunction with other clinical and morphologic biomarkers to prognosis has been less well investigated.

Methods

We performed a multicenter, retrospective study of MPN-U (94 cases) to better define the clinicopathologic features, genetic landscape, and clinical outcomes, including subgroups of early-stage, advanced-stage, and coexisting disorders. The Dynamic International Prognostic Scoring System (DIPSS) plus scoring system was applied to assess its relevance to MPN-U prognosis.

Results

Multivariate analysis demonstrated bone marrow blast count and DIPSS plus score as statistically significant in predicting overall survival. Univariate analysis identified additional potential poor prognostic markers, including abnormal karyotype and absence of JAK2 mutation. Secondary mutations were frequent in the subset analyzed by next-generation sequencing (26/37 cases, 70.3%) with a borderline association between high molecular risk mutations and overall survival.

Conclusions

This study, as one of the largest of MPN-U studies incorporating both clinicopathologic and molecular data, moves toward identification of biomarkers that better predict prognosis in this heterogeneous category.

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Dr. Guo Develops Test Promising Answers for Cancer Patients

Cancer researcher, Belinda Guo, knows that one of the biggest issues for people with myeloproliferative neoplasms (a group of rare blood cancers), is not knowing if the cancer will progress.

Dr Belinda Guo and her team at the University of Western Australia’s Translational Cancer Pathology Laboratory have invented a new blood-based test that detects specific changes in the blood of patients diagnosed with myelofibrosis.

With funding from Cancer Council WA, they are now working with clinicians to assess the blood of individuals who have undergone a bone marrow transplant to see if the transplant has worked.

We sat down with Belinda to hear more about her research project. Read the full interview below.

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New study paves the way for precision drugs to treat blood cancers

by Tampere University

April 4, 2024

The Janus kinase 2 (JAK2) protein mediates signaling from several cytokine receptors in the regulation of hematopoiesis and immune responses. Somatic mutations in human JAK2 lead to constitutive activation and cytokine-independent signaling and underlie several hematological malignancies from myeloproliferative neoplasms (MPN) to acute leukemia and lymphomas. JAK2 contains an active kinase domain and an inactive pseudokinase domain. Interestingly, pathogenic mutations mainly occur in the regulatory pseudokinase domain.

Due to its critical pathogenic role, JAK2 has become an important therapeutic target. The four currently approved JAK2 inhibitors relieve symptoms but do not heal the patient or affect survival. These drugs target the highly conserved kinase domain and affect both normal and mutated JAK2 and, due to side effects, carry a black box warning that limits their use in elderly, cardiac and cancer patients. The selective inhibition of pathogenic JAK2 is a key pending goal in drug discovery that requires a precise mechanistic understanding of the regulation of JAK2 activation.

“To understand the molecular and structural basis of the physiological and pathogenic activation of JAK2, we used single-molecule microscopy and erythropoietin receptor (EpoR) as a model system.

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A new mouse model highlights the need for better JAK inhibitors in myeloproliferative neoplasms

Charles E. de Bock

The discovery that the gain of function JAK2 V617F mutation is present in myeloproliferative neoplasms (MPNs) has led to numerous clinical trials assessing the efficacy of JAK inhibitors. Most notably, ruxolitinib, a combined JAK1/2 selective inhibitor, has gained approval in patients with myeolofibrosis (MF), and additional JAK2 inhibitors including fedratinib, pacritinib, and momelotinib also under evaluation for patients with MF. However, while these inhibitors demonstrate some clinical benefit, they do not adequately reduce the mutant clone fraction. 1 , 2 Consequently, a critical question for the field has been whether the lack of a durable response is attributed to either (i) the inability of current JAK inhibitors to completely block the pathway or (ii) the possibility that mutant clones are not entirely dependent on this activated pathway.

To address these two possibilities, a new study from the laboratory of Ross Levine, published in Cancer Discovery,developed an innovative mouse model of Jak2 V617F alone or in combination with Tet2 loss. The novel aspect of this mouse model lies in the ability to control the expression and genetic deletion of Jak2 V617F allele from mutant clones upon development of MPN. To do so, it utilizes two orthogonal site‐specific recombinases which exert precise control over the temporal expression and deletion of the Jak2 V617F allele.

The mouse model uses the well‐established Cre recombinase that recognises short nucleotide target sequences called Lox sites, in conjunction with the relatively new Dre recombinase which recognizes short nucleotide sequences called Rox sites. Importantly, the strategic arrangement and orientation of these sequences can lead to either flipping or deletion of the intervening DNA sequence. In this context, Dre recombinase is employed to initiate the expression of the Jak2 V617F allele. Subsequently, a modified CreER recombinase, translocated to the nucleus upon tamoxifen treatment, can delete the Jak2 V617F allele (Figure 1A). This intricate mouse model provided a powerful tool for comparing the durability of response between JAK inhibitors and the genetic loss of Jak2 V617F in the context of MPNs.

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