SVR With Pacritinib Is Linked With OS Benefit in Myelofibrosis With Thrombocytopenia

May 26, 2025

Author(s): Ashling Wahner

Fact checked by: Gina Mauro

The achievement of spleen volume response (SVR) of at least 10% (SVR10) at week 12 with pacritinib (Vonjo) was positively associated with overall survival (OS) in patients with myelofibrosis and thrombocytopenia, although more stringent SVR thresholds were not significantly associated with OS, according to findings from a post hoc landmark analysis of the phase 3 PERSIST-2 trial (NCT02055781).1

The investigators assessed OS among SVR responders vs nonresponders using 4 different SVR thresholds: at least 35% (SVR35), at least 20% (SVR20), SVR10, and greater than 0% (SVR0). The data, which were published in the European Journal of Haematology, showed that the greatest separation of OS curves between responders and nonresponders was observed among patients who received pacritinib (n = 89) at 200 mg twice daily and achieved SVR10 vs those who did not respond at that threshold (HR, 0.00; 95% CI, 0.00-0.14; < .01). No deaths were observed among the responders, whereas 5 nonresponders died.

“We found that a significant association was not observed with more stringent SVR or total symptom score [TSS] thresholds, likely because the number of responders was lower, and thus a larger number of observations would be needed to detect statistical significance at such thresholds,” lead study author Helen Ajufo, MD, MS, of the Department of Medicine, Leukemia Service, at Memorial Sloan Kettering Cancer Center, in New York, New York, and coinvestigators explained in the paper.

SVR0 and SVR20 also conferred improved OS, although these more stringent response thresholds were less prognostic of the pacritinib survival benefit.

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Real-World Data Shows Favorable Efficacy and Safety With Busulfan for MPNs

Busulfan treatment of myeloproliferative neoplasms (MPNs) demonstrated high response rates and infrequent adverse events (AEs), according to a study of real-world data from hospitals in the United Kingdom.

“Given the lack of prospective studies on the use of busulphan, our study contributes valuable real-world data on the safety and efficacy of busulphan which clinicians should find useful in managing this challenging cohort,” the researchers wrote in their report.

In the retrospective study, researchers analyzed data from 115 patients with MPNs from 13 hospitals. The median age of the cohort was 78 years and 44% of patients were male. The majority of patients had a diagnosis of essential thrombocythemia (ET) at 67%, followed by 24% with polycythemia vera (PV), 5% with MPN not otherwise specified, and 4% with myelofibrosis. JAK2 and CALR mutations were present among 62% and 13% of patients, respectively.

There were 16% of patients with a history of malignancy, including 8% of nonmelanoma skin cancers, and 8% with cancers that included those of the breast, prostate, lung, low-grade lymphoma, and melanoma.

One previous line of therapy (LOT) had been received by 13% of patients, 63% had 2 LOTs, 19% had 3 LOTs, and 5% had 4 LOTs. The most common previous cytoreductive therapy was hydroxycarbamide (78%), followed by anagrelide (16%), pegylated interferon (8%), P32 (3%), and ruxolitinib (2%).

The dosing regimens of busulfan included repeated single doses (31%) with a median dose of 38 mg, 1- to 4-week courses (30%) with a median dose 3.5 mg, and continuous therapy lasting more than 4 weeks (35%) with a median dose of 2 mg.

Our study contributes valuable real-world data on the safety and efficacy of busulphan which clinicians should find useful in managing this challenging cohort.

The median time from busulfan initiation to last follow-up or death was 23 months. There were 14% of patients who were alive with acceptable blood count control without any other cytoreductive therapy.

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Interferon Lowers Myelofibrosis Risk in Young Patients With Polycythemia Vera, Essential Thrombocytopenia

May 15, 2025

Author(s): Alexandra Gerlach, Associate Editor

Early treatment with interferon reduced secondary myelofibrosis (sMF) risk in adolescent and young adult (AYA) patients with polycythemia vera (PV) or essential thrombocytopenia (ET), according to study data published in Leukemia.1

Red blood cells | Image Credit: © fotogurmespb - stock.adobe.com

MF is an incurable, rare hematologic malignancy characterized by the overproduction of red blood cells. This causes bone marrow scarring, which leads to severe anemia—a key factor impacting overall survival (OS) for patients with MF. It can develop as a primary disease or secondary to ET and PV, as well as progress to acute myeloid leukemia in some cases. Although MF is primarily diagnosed in older adults, 20% of cases are in individuals under the age of 40.1,2

AYA patients with ET or PV face unique clinical challenges due to their longer life expectancy because of a lack of data on long-term outcomes and treatment strategies. Existing guidelines are specific to older populations, despite the unique clinical considerations in younger patients.1

“These patients are expected to live for several decades, and the accumulation of additional thrombotic risk factors (age, cardiovascular conditions, additional mutations) may progressively heighten this risk,” the authors wrote. “This highlights a substantial and emerging concern regarding thrombotic events in this younger demographic.”1

The study evaluates complication rates, including thrombosis and progression to sMF, and the impact of interferon (IFN) on outcomes in patients diagnosed before the age of 25. The primary outcomes of the study were thrombosis-free survival (TFS), myelofibrosis-free survival (MFS), and OS in the entire cohort and for ET and PV patients separately, and the impact of treatment on these outcomes. Secondary outcomes were identification of risk factors associated with thrombotic events and sMF.1

The study included a total of 348 patients, of whom 278 were diagnosed with ET and 70 with PV, with a median age at diagnosis of 20 years. The incidence of thrombotic events was about 1.9 per 100 patient-years, with elevated white blood cell count (≥ 11 × 109/L) and absence of splenomegaly at diagnosis identified as significant risk factors. However, cytoreductive therapy did not reduce thrombotic risk. The incidence of sMF was 0.7 per 100 patient-years, with CALR mutations and a history of thrombosis associated with higher risk.1

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Seiter Explores Time of Initiation and Alternate Dosing of Ruxolitinib in Myelofibrosis

By Targeted Oncology Staff
Fact checked by Jonah Feldman

During a live event, Karen Seiter, MD, discussed the role of the JAK/STAT pathway in myeloproliferative neoplasms and the use of ruxolitinib to treat myelofibrosis.

Karen Seiter, MD

Karen Seiter, MD

Professor of Medicine
New York Medical College
Director of  the Adult Leukemia Service
Westchester Medical Center
Valhalla, NY

CASE SUMMARY

  • A 68-year-old woman presented to her physician with symptoms of mild fatigue.
  • Spleen was palpable 6 to 7 cm below the left costal margin
  • Past medical history: no known comorbidities
  • Next-generation sequencing testing: JAK2 V617F mutation
  • Karyotype: 46,XX
  • Bone marrow biopsy: megakaryocyte proliferation and atypia with evidence of reticulin fibrosis
  • Blood smear: leukoerythroblastosis
  • Diagnosis: primary myelofibrosis

Risk

  • Dynamic International Prognostic Scoring System: intermediate-1
  • Mutation-Enhanced International Prognostic Scoring System for Transplantation-Age Patients: intermediate risk

Laboratory Values

  • Red blood cell count: 3.40 ×106/μL
  • Hemoglobin level: 9.7 g/dL
  • Hematocrit: 32.3%
  • Mean corpuscular volume: 94 μm3
  • White blood cell count: 23,000/μL
  • Platelet count: 450,000/μL
  • Peripheral blood blasts: <1%

Peers & Perspectives in Oncology: What disease states are currently classified as myeloproliferative neoplasms (MPNs)?

Seiter: The latest classification is the 2022 World Health Organization [WHO] classification.1,2 As a clinician, when we have myeloproliferative diseases, we think of MPNs [as meaning the patient] has too much of something: The WBC count is too high but with maturing myeloid and not with a lot of blasts, or the hemoglobin [level] is too high, or the [platelet count is] too high. That would be potentially chronic myelocytic leukemia [CML], polycythemia vera [PV], essential thrombocytopenia [ET], and for primary myelofibrosis, the most common presentation would be somebody with either anemia, with abdominal distension or early satiety from splenomegaly. The WBC count could be high; it could be low; platelets could be high, or they could be low.

When we’re working up patients with MPN, the first step is always to make sure that they don’t have CML, because CML can look like myelofibrosis because CML can present with a high platelet count. The first step is always to [test for] the Philadelphia chromosome and perform BCR::ABL1 testing to make sure it’s not CML.

Most of these patients are going to have a bone marrow [biopsy] done. There’s always the debate about, if you have somebody with a hemoglobin level of 20 g/dL, where it looks pretty clear that they have PV, do you need a bone marrow [biopsy] in order to formally diagnose the patient? You do because that’s part of the diagnostic criteria. But sometimes, if you have a much older patient with frailty, you have to consider the goals of care. Sometimes, there may be cases of patients who don’t get the bone marrow biopsy done. The only time it would be reasonable is if the hemoglobin level is high; for anything else, there are so many other things that [it] could be that it’s important to do the bone marrow biopsy for a diagnosis.

Mastocytosis used to be [listed among the] MPNs, but [the WHO] made it its own classification. MPNs with eosinophilia are a separate category. Now we have the myelodysplastic syndrome [MDS]/MPN overlap; that’s a separate category. Then, we have MDS, secondary myeloid neoplasms, and acute myeloid leukemia.

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Fedratinib Shows Promise in Rare Myeloproliferative Neoplasms

By Andrew Kuykendall, MD

Andrew Kuykendall, MD, an assistant member at the H. Lee Moffitt Cancer Center of University of South Florida in Tampa, FL, discusses data from a phase 2 trial (NCT05177211) which evaluated fedratinib (Inrebic), a JAK2-selective kinase inhibitor, in patients with atypical chronic myeloid leukemia (aCML), chronic neutrophilic leukemia (CNL), myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN)-unclassifiable, and MDS/MPN-ring sideroblasts and thrombocytosis per the 2016 WHO classification.

According to findings from this multi-institutional, investigator-initiated study presented at the 2024 American Society of Hematology (ASH) Annual Meeting, fedratinib demonstrated promising efficacy and a manageable safety profile in this patient population.

At the time of data cutoff, 24 patients were enrolled and 19 patients were evaluable. A total of 53% of patients achieved a response at 24 weeks, including 50% symptom responses and 37.5% spleen responses. Of those treated for ≥24 weeks, spleen volume decreased by an average of 32%, and 85% showed symptomatic improvement. Responses were enriched in patients with CSF3R mutations (83%) and JAK-STAT pathway mutations (70%). Further, the median overall survival (OS) was estimated at 19.7 months.

“This was a very high-risk population, as these diagnoses are associated with poor prognosis. Despite that, we observed spleen responses in approximately 35% of patients, symptom responses in 50%, and some durable responses, with the median time on treatment nearing a year. These outcomes were particularly exciting given the molecular features of this patient population, which typically predict lower response rates,” Kuykendall shares.

Safety findings showed that fedratinib was well tolerated, The majority of adverse events (AEs) were grades 1 or 2, and the most commonly seen AEs were diarrhea (37.5%), constipation (37.5%), and anemia (29%). A single grade 4 neutropenia event resolved with dose adjustments.

“Regarding the safety profile, it was consistent with prior studies of fedratinib. There were some manageable low-grade gastrointestinal [adverse events]. We implemented a more proactive approach to mitigate these, including the use of antiemetics during the first 8 weeks. Overall, the [adverse event] profile remained manageable, and the efficacy outcomes likely exceeded our initial expectations,” adds Kuykendall.

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Ruxolitinib Discontinuation at Conditioning Does Not Increase GVHD Risk in Myelofibrosis

May 7, 2025

Author(s): Alexandra Gerlach, Associate Editor

Stopping ruxolitinib (Jakafi; Incyte Corp) prior to the conditioning regimen may not influence graft-versus-host disease (GVHD) risk more than in patients with myelofibrosis (MF), according to data published in Cancer Immunology, Immunotherapy.1

MF is an incurable, rare hematologic malignancy that is part of a group of diseases called myeloproliferative neoplasms, which are characterized by the overproduction of red blood cells. This causes bone marrow scarring, leading to severe anemia—a key factor impacting overall survival for patients with MF. Other symptoms include fatigue, enlarged spleen, night sweats, bone pain, and weight loss. MF can develop as a primary disease or secondary to essential thrombocythemia and polycythemia vera. In some cases, it can progress to acute myeloid leukemia.2

Ruxolitinib is the standard of care for first-line treatment of patients with MF that was originally approved by the FDA in 2011 for the treatment of intermediate- and high-risk MF. It was also the first approved treatment for patients 12 years of age and older with steroid-refractory acute GVHD in 2019. Ruxolitinib is a Janus kinase (JAK) 1/2 inhibitor that targets the JAK/STAT pathway, a critical cellular signaling pathway that helps cells respond to cytokines. Identification of mutations within the JAK/STAT pathway paved the way for the development of agents such as ruxolitinib, fedratinib (Inrebic; Bristol Myers Squibb), momelotinib (Ojjaara; GSK), and pacritinib (Vonjo; CTI BioPharma).2,3

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FDA Grants Fast Track Designation to Givinostat for Polycythemia Vera

May 6, 2025

Author(s): Jax DiEugenio

Fact checked by: Chris Ryan

The FDA has granted fast track designation to givinostat (Duvyzat), an orally administered histone deacetylase (HDAC) inhibitor, for the treatment of patients with polycythemia vera (PV).1

The agent is being evaluated in the ongoing phase 3 GIV-IN PV trial (NCT06093672), which aims to compare the efficacy and safety of givinostat to hydroxyurea in patients with JAK2 V617F–positive, high-risk PV, which is characterized by the clonal overproduction of erythroid, myeloid, and megakaryocytic lineages within the bone marrow. By targeting aberrant gene expression, givinostat may suppress pathologic cell proliferation associated with driver mutations such as JAK2 V617F, which are common in patients with PV.

“The FDA decision to grant givinostat fast track designation underscores the urgent need for innovative treatments for PV and highlights the potential of givinostat to make a meaningful difference,” Paolo Bettica, MD, PhD, chief medical officer at Italfarmaco Group, stated in a news release. “We look forward to working closely with the FDA as we plan for completion of our phase 3 clinical trial.”

The FDA and European Medicines Agency both previously granted orphan drug designation to givinostat for PV. In the United States, the FDA previously approved givinostat for the treatment of patients 6 years of age or older with Duchenne muscular dystrophy.2

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Real-World Findings Confirm Clinical Data on Momelotinib in MF With Anemia

May 1, 2025

Author(s): AJMC Contributor

Real-world insights on momelotinib (Ojjaara; GlaxoSmithKline) in patients with myelofibrosis (MF) and anemia have been published, showing consistent and, in some cases, better results than those shown previously in clinical studies of the drug.1

The results offer some of the first glimpses into real-world findings of the Janus kinase (JAK) inhibitor, which received approval toward the end of 2023, becoming the first and only treatment indicated for patients with MF and anemia.2

“This study presents the largest real-world cohort of MF patients treated with momelotinib and is the first to apply the recently proposed 2024 criteria for anemia response,” wrote the researchers, publishing the insights in Blood Cancer Journal.1

The retrospective study included 122 patients with MF and anemia across multiple treatment centers. Patients had disease-related symptoms or symptomatic splenomegaly and could be JAK-naive (23.4%) or previously received treatment with a JAK inhibitor (76.6%).

At treatment initiation, 73.8% of patients were dependent on transfusions. Among these patients, the median Hb level increased from 7.7 g/dL (range, 4.7-9.8) at treatment initiation to 8.7 g/dL at 3 months of follow-up. By 6 months, 30.6% of patients had major responses and 36.1% had minor responses. At the time follow-up point, median red blood cell transfusion frequency had dropped from 4 units per month to 1 unit per month.

The results offer some of the first glimpses into real-world findings of the JAK inhibitor momelotinib, which was approved in 2023.

Among the remaining patients who were not dependent on transfusions at treatment initiation, the median Hb level increased from 8.9 g/dL (range, 7.2-10.8) to 10.2 g/dL. At 6 months of follow-up, 36.4% of patients demonstrated a major response, and 27.3% demonstrated a minor response.

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Prediction of resistance to hydroxyurea therapy in patients with polycythemia vera: a machine learning study (PV-AIM) validated in a prospective interventional phase IV trial (HU-F-AIM)

Published April 25, 2025

Florian H. Heidel, Valerio De Stefano, Matthias Zaiss, Jens Kisro, Eva Gückel, Susanne Großer, Mike W. Zuurman, Kirsi Manz, Kenneth Bryan, Armita Afsharinejad, Martin Griesshammer & Jean-Jacques Kiladjian

Abstract

Polycythemia vera (PV) is a myeloproliferative neoplasm associated with increased thromboembolic (TE) risk and hematologic complications. Hydroxyurea (HU) serves as the most frequently used first-line cytoreductive therapy worldwide; however, resistance to HU (HU-RES) develops in a significant subset of patients, leading to increased morbidity and necessitating alternative treatments. This study, part of the PV-AIM project, employed machine learning techniques on real-world evidence (RWE) from the Optum® EHR database containing 82.960 PV patients to identify baseline predictors of HU-RES within the first 6–9 months of therapy. Using a Random Forest model, the study analyzed data from 1850 patients, focusing on laboratory parameters and clinical characteristics. Key predictive markers included red cell distribution width (RDW) and hemoglobin (HGB), showing the strongest association with HU-RES. A synergistic interaction between RDW and HGB was identified, enabling TE risk stratification. This study provides a robust framework for early detection of HU-RES using readily available clinical data, facilitating timely intervention. These findings underscore the importance of personalized treatment approaches in managing PV and highlight the utility of machine learning in enhancing predictive accuracy and clinical outcomes. Based on the results of PV-AIM we initiated an open-label, prospective, single-arm, interventional, phase IV study (HU-F-AIM) evaluating HU-resistance/intolerance. Validation of predictive biomarkers may facilitate identification of patients at risk of HU resistance who may benefit from alternative treatment options, possibly preventing ongoing phlebotomy during HU treatment, a frequent therapeutic choice in high-risk PV associated with early disease progression and increased thromboembolic complications. We propose an updated terminology that differentiates between true molecular resistance and clinical resistance, that may indicate the requirement for alternative therapeutic strategies.

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Assessing Risk for JAK Inhibitor Selection in Myelofibrosis

By Targeted Oncology Staff

In part 1, experts explores how assessing individual risk factors is crucial in selecting the appropriate JAK inhibitor for patients with myelofibrosis.

CASE

AARON T. GERDS, MD, MS: How do you use molecular testing, bone marrow results, and clinical features to stratify risk in patients with myelofibrosis?

PRITHVIRAJ BOSE, MD: At this point, I believe we are all receiving the myeloid mutation panels. We also order JAK2MPL, and CALR: the 3 drivers. However, most clinicians would order a myeloid mutation panel because we know that many of the mutations are prognostic. This is the whole point of risk stratification, which is now increasingly sophisticated and integrates multiple clinical, molecular, [and] cytogenetic variables to determine who needs a transplant.

These are the first actions I take when speaking with a new patient. I get an idea of their risk in terms of survival and prognosis, and that informs my decision to refer them to transplant. I then counsel the patient appropriately.

I do not believe molecular testing informs treatment because our drugs are, for the most part, mutation agnostic. All we have are JAK inhibitors, which are not mutation specific. However, from a prognostic standpoint, the [role] of molecular testing is key.

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