Optimal Ruxolitinib Dosing in Myelofibrosis Critical for Improved Effectiveness, Survival in Real-World Setting

March 27, 2025

Author(s): Luke Halpern, Assistant Editor

Patients with myelofibrosis (MF) started on appropriate and highest tolerated doses of ruxolitinib (Jakafii; Incyte Corporation) experienced better trends in response and improved health-related quality of life (HRQoL), highlighting the importance of proper ruxolitinib dosing, timing, and administration to ensure the most effective patient responses in terms of symptom relief, spleen size reduction, and improved overall survival (OS).1

Diagnosis of Myelofibrosis. Laboratory blood bottle (tube), glass slide with blood smear, hematology test, stethoscope lying on notebook with printed text hematological diagnosis

Ruxolitinib is effective at reducing symptoms in myelofibrosis. | Image Credit: © shidlovski – stock.adobe.com

It’s critical for treatment providers administering ruxolitinib for MF to know the expected real-world presentation of treatment complications. Patients being administered ruxolitinib face higher health care resource utilization and clinical burdens, including an increased risk of anemia development and adverse treatment events. Still, the treatment is highly effective when dosed and administered appropriately and when proper consideration of adverse events, such as anemia or graft-versus-host disease, is included in counseling.1,2

According to the investigators, the expected optimal starting dose for initiating ruxolitinib is based on a patient’s baseline platelet count. Further dose titration—up to 25 mg twice daily—can be utilized to maximize efficacy, which has been demonstrated to be dose-dependent. However, suboptimal adherence is consistently reported among patients treated with ruxolitinib, which could contribute to poor survival outcomes and undermine disease control.1,3

Poor adherence rates have been observed in the ongoing Ruxolitinib Observational Study in Myelofibrosis Treated Patients in Italy (ROMEI), an observational study of ruxolitinib-treated patients with MF in Italy. Twenty-four-week findings confirmed ruxolitinib’s therapeutic effects and a favorable safety profile but also indicated that up to one third (25% to 40%) of patients receiving ruxolitinib could have been undertreated despite their clinical presentation necessitating higher doses. An interim analysis, conducted by the current authors, was commissioned to investigate ruxolitinib dosing patterns and correlations with clinical outcomes in patients who completed the first 12 months of follow-up or prematurely discontinued the ROMEI trial.1

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Thrombosis, Major Bleeding Events More Frequent in Myelofibrosis Compared With Other Myeloproliferative Neoplasms

March 26, 2025

Author(s): Luke Halpern, Assistant Editor

Results of a nationwide Swedish population-based study indicate that patients with myelofibrosis (MF) have increased rates of thromboembolic events and major bleeding compared with presentations in other myeloproliferative neoplasms (MPN), with thromboembolic complications and major bleeding events diverging based on varying treatment groups. These results, published by study authors in Blood Advances, can help health care providers more effectively care for patients with MF, allowing them to counsel patients on associated bleeding risks.1

Thrombosis can be a deadly complication in patients with myelofibrosis. | Image Credit: © Matthieu – stock.adobe.com

The clinical presentation of MF evolves throughout the development of the disease, eventually presenting as bone marrow fibrosis, hepatosplenomegaly, fatigue, and progressive pancytopenia, ultimately leading to reduced patient quality of life and heightened morbidity. Bleeding and thromboembolic events have been known to be possible complications of MF, but literature on this association is lacking. According to the present investigators, studies analyzing this association are plagued by small cohorts, seldom-included control patients, and populations containing varying MPNs, rather than MF specifically.2,3

To fill the present gaps in literature regarding thromboembolic and bleeding event prevalence in patients with MF, the current study authors conducted a nationwide analysis to assess the frequency of arterial and venous events, major bleeding, all-cause stroke, and all-cause mortality in Swedish patients with primary MF (PMF) and secondary MF (SMF) compared with matched controls. They also aimed to investigate if outcomes varied based on the therapy used in MF while attempting to describe relevant risk factors for major bleeding and thromboembolic events among patients with MF.1

Multiple Swedish registries of patients diagnosed with hematologic malignancies were consulted, with all adult patients registered with a diagnosis of MF from 2008 to 2021 included. In total, 1079 patients with MF and 395 controls were included, with a median age of 72 years at diagnosis. Notably, over a third of the patients (40.7%) had an International Prognostic Scoring System (IPSS) score of intermediate-2 or high risk. Furthermore, mutations were present in many patients enrolled in the study and diagnosed after June 1, 2016, with 53.6% having a JAK2 V617F mutation.1

Across the follow-up period, 125 arterial and 51 venous events occurred in the MF cohort, with event rates of 2.59 and 1.06 events per 100 patient years, compared with 337 (rate 1.51, HR: 1.73; 95% CI, 1.40-2.12; < .001) and 86 (rate 0.38, HR: 2.75; 95% CI, 1.95-3.90; P < .001) among the control patients. When patients were divided based on diagnoses of PMF or SMF, rates of arterial and venous events were noticeably higher among patients with SMF compared with PMF. In addition, 80 cases of acute myocardial infarction (rate: 1.66), 40 ischemic strokes (rate: 0.83), and 38 pulmonary emboli (rate: 0.79) were documented in the MF cohort.1

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Real World Management of Cytopenias and Infections in Patients With Myelofibrosis Treated With Ruxolitinib

Liesl A. Butler, Cecily Forsyth, Claire Harrison, Andrew C. Perkins

ABSTRACT
Introduction: Ruxolitinib was the first JAK2 inhibitor approved for the treatment of primary and secondary myelofibrosis. It is
currently used worldwide as first-line therapy for advanced disease (intermediate-2 and high-risk) and is effective in polycythaemia
vera (PV) and essential thrombocythaemia (ET), but not funded for this indication in many countries. Ruxolitinib has proven
benefits with respect to symptom control, reduction in spleen size and prolongation of survival; however, it rarely induces a
substantial reduction in allele burden and never provides a cure. Moreover, there are frequently encountered adverse effects and
dosing issues that require careful management to optimise its therapeutic benefit.

Methods and Results: In this case-based review, we use seven informative common clinical scenarios to discuss appropriate
investigation and management of cytopenias and infection issues.

Conclusions: We make recommendations based on 15 years of experience in using ruxolitinib and other JAK inhibitors for the
treatment of myelofibrosis. We discuss when allogeneic haematopoietic stem cell transplantation (AHSCT) should be considered
and some of the currently available alternative JAK inhibitors and trial options when AHSCT is not an option.

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Emerging Therapies in Myelofibrosis Could Extend Beyond JAK Inhibitors

March 24, 2025

Author(s): Ashley Chan

Fact checked by: Ashling Wahner

The September 2023 FDA approval of momelotinib (Ojjaara) for the treatment of patients with primary and secondary myelofibrosis with anemia provided the treatment paradigm with its fourth FDA-approved JAK inhibitor, a class of drugs that has helped improve symptoms associated with myelofibrosis and decrease spleen size, according to Raajit Rampal, MD, PhD.

Additional classes of drugs, such as BET inhibitors and immunotherapy agents, are also currently under investigation in clinical trials and could become “game-changers” if effective, Rampal noted.

“The major [message is] that myelofibrosis is not a monolithic disease, and the selection of the treatment needs to be tailored to the underlying issues and challenges the patient is facing,” said Rampal in an interview with OncLive®.

In the interview, Rampal discussed currently available JAK inhibitors and their limitations, emerging treatments for myelofibrosis, tips for treatment selection, and his takeaways from the 6th Annual Miami Cancer Institute Global Summit on Immunotherapies for Hematologic Malignancies.

Rampal is a hematologist-oncologist, the director of the Center for Hematologic Malignancies, and the director of the Myeloproliferative Neoplasms Program at Memorial Sloan Kettering Cancer Center in New York, New York.

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Optimizing Myelofibrosis Care in the Age of JAK Inhibitors

Author: Douglas Tremblay, MD

How do you assess a patient’s prognosis at the time that they are diagnosed with myelofibrosis?
In the clinic, we use several scoring systems that have been developed based on the outcomes of hundreds of patients with myeloproliferative neoplasms (MPNs) to try to predict survival from time of diagnosis. Disease features associated with a poor prognosis include anemia, elevated white blood cell count, advanced age, constitutional symptoms, and increased peripheral blasts. Some of these scoring systems also incorporate chromosomal abnormalities as well as gene mutations to further refine prognostication.1

Determining prognosis can be important to creating a treatment plan, particularly to decide if curative allogeneic stem cell transplantation is necessary. However, I always caution patients that these prognostic scoring systems cannot tell the future and that each patient may respond differently to treatment.

How do you monitor for disease progression?
I will discuss with patients how they are feeling in order to determine if there are any new or developing symptoms that could be a sign that their disease is progressing. I will also review their laboratory work looking for changes in blood counts that could be a signal of disease evolution.

For instance, development of anemia or thrombocytopenia may signal worsening bone marrow function or progression to secondary acute leukemia. If there are concerning signs or symptoms, I will then perform a bone marrow biopsy with aspirate that will include assessment of mutations and chromosomal abnormalities to determine if their disease is progressing.

What are the first-line treatment options for a patient newly diagnosed with myelofibrosis, and how do you determine the best course of action?
For patients with myelofibrosis, the first-line treatment options include Janus kinase (JAK) inhibitors, which are effective at improving spleen size and reducing symptom burden. The US Food and Drug Administration (FDA) has approved 4 JAK inhibitors for the treatment of myelofibrosis: ruxolitinib, fedratinib, pacritinib, and momelotinib (Table).2-13 In general, ruxolitinib is the first-line treatment option unless there is thrombocytopenia, in which case pacritinib is more appropriate. In patients with baseline anemia, momelotinib may be the best choice.

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Pelabresib Plus Ruxolitinib Improves Spleen Responses in Myelofibrosis

By Roman Fabbricatore
Fact checked by Russ Conroy

Pelabresib (CPI 0610) in combination with ruxolitinib (Jakafi) significantly improved spleen responses and elicited robust clinical activity compared with placebo/ruxolitinib in patients with JAK inhibitor-naïve myelofibrosis, according to results from the phase 3 MANIFEST-2 trial (NCT04603495) published in Nature Medicine.1

Efficacy data from the trial revealed that the primary end point of spleen volume reduction of at least 35% at week 24 favored the investigational combination vs the placebo arm: 65.9% vs 35.2%, respectively (difference, 30.4%; 95% CI, 21.6%-39.3%; P <.001). Additionally, the mean percent change at week 24 in the respective arms was –50.6% (95% CI, –53.2% to –48.0%) vs –30.6% (95% CI, –33.7% to –27.5%). Spleen volume response was consistently higher with pelabresib vs placebo across predefined subgroups.

Furthermore, the hemoglobin response rate, defined as a 1.5 g/dl or greater mean increase, occurred in in 10.7% of the pelabresib arm (95% CI, 6.60%-14.90%) vs 6.0% of the placebo arm (95% CI, 2.85%-9.19%). Transfusions were received in the first 24 weeks of treatment in 27.6% and 37.5% of respective arms.

Greater reductions in NF-κB-regulated cytokines (–32.1% [95% CI, –34.9% to –29.2%] vs –19.4% [95% CI, –22.5% to –16.2%]), tumor necrosis factor (TNF; –43.5% [95% CI, –47.0% to –39.8%] vs –26.4% [95% CI, –30.5% to –22.1%]), and interleukin-6 (IL-6; –35.4% [95% CI, –44.2% to –25.2%] vs –14.5% [95% CI, –25.2% to –2.3%]) were seen in the investigational arm vs the placebo arm. Of note, a reduction in IL-8 levels was observed with pelabresib (–14.3% [95% CI, –22.3% to –5.5%]), but an increase was observed in the placebo arm (31.2% [95% CI, 17.5%-46.5%).

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Dr Rampal on ​Emerging Therapies Under Investigation in Myelofibrosis

March 17, 2025

Author(s): Raajit K. Rampal, MD, PhD

Fact checked by: Ashling Wahner ,Chris Ryan

Raajit Rampal, MD, director of the Center for Hematologic Malignancies and director of the Myeloproliferative Neoplasms Program at Memorial Sloan Kettering Cancer Center, discusses emerging treatments for patients with myelofibrosis.

The therapeutic paradigm for myelofibrosis continues to expand with emerging treatment options, particularly with combination therapies, novel JAK inhibitors, and immunotherapeutic agents, Rampal begins. Among these, pelabresib (CPI-0610), a BET inhibitor, has completed phase 3 trials. Preliminary data from the phase 3 MANIFEST-2 trial (NCT04603495), which were presented in December 2023, demonstrated improved spleen responses and a trend toward better symptom management with the combination of pelabresib and ruxolitinib (Jakafi) vs placebo plus ruxolitinib in patients with JAK inhibitor–naive myelofibrosis. Updated findings from MANIFEST-2 were published in Nature Medicine in March 2025.

Beyond pelabresib, several other agents are currently in phase 3 trials for patients with myelofibrosis, Rampal says. Selinexor (Xpovio), which is currently FDA approved for the treatment of patients with relapsed/refractory multiple myeloma, is being studied in combination with ruxolitinib in patients with myelofibrosis in the phase 3 XPORT-MF-034 trial (NCT04562389). Additionally, navtemadlin (KRT-232), an MDM2 inhibitor, is undergoing clinical evaluation in patients with myelofibrosis. Notably, these trials are ongoing, and no conclusive data are available at this time, Rampal emphasizes.

The development of next-generation JAK inhibitors also represents a promising area of investigation, according to Rampal. These newer inhibitors are anticipated to demonstrate greater potency and selectivity compared with existing agents, though they remain in early-phase clinical trials, he notes.

Rampal states that one of the most exciting advancements in this setting is the emergence of immunotherapies. Calreticulin-targeted antibodies are currently being evaluated in clinical trials, and 2 candidates are in development, he reports. If these agents prove effective, they could significantly alter the treatment paradigm, he concludes.

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Jakafi May Not Associate with Long-Term Benefits in Myelofibrosis Subset

March 16, 2025

Author(s): Spencer Feldman

Fact checked by: Alex Biese

Among patients with calreticulin (CALR)-mutated myelofibrosis, real-world data reveal insights into those with splenomegaly and/or symptoms requiring therapy with Janus kinase 2 (JAK2) inhibitors.

The findings suggest that while Jakafi (ruxolitinib) shows some initial benefits, CALR-mutated patients may require more targeted and innovative therapeutic approaches for better long-term outcomes, according to study findings published in Annals of Hematology.

“Overall, despite the initial benefits of [Jakafi], CALR-mutated patients may require more innovative therapeutic interventions to achieve optimal outcomes. This further emphasizes the necessity of exploring alternative or adjunctive therapies tailored specifically for CALR-mutated individuals,” lead study author Dr. Francesca Palandri and colleagues wrote in the study.

Palandri is currently an adjunct professor primarily based in the Department of Experimental, Diagnostic and Specialty Medicine at the Università di Bologna, Bologna, Italy. She is also a junior researcher at Azienda Ospedaliero-Universitaria di Bologna, Institute of Hematology, Bologna, Italy.

Patients with CALR mutations began Jakafi with more severe disease, including higher peripheral blast counts, lower hemoglobin levels and worse marrow fibrosis, and after a longer median time from diagnosis (2.6 versus 0.7 years) compared to patients with JAK2 mutations. At six months, spleen responses were numerically lower in CALR-mutated patients, who also had lower rates of symptom responses (56.1% versus 66.7%, respectively). However, CALR-mutated patients experienced lower rates of high white blood cell counts.

Furthermore, in patients with delayed Jakafi initiation, anemia and reduced starting doses correlated with poorer survival. Managing anemia through interventions like danazol, erythropoiesis-stimulating agents, iron chelation and optimized Jakafi dosing may improve outcomes, according to study authors. The study also highlights the potential benefits of alternative JAK2 inhibitors with lower hematological toxicity.

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Optimizing Treatment in Patients With Myelofibrosis and Transfusion-Dependent Anemia

By Clinical Content Hub

In patients with MF, greater anemia severity and transfusion dependency have been linked to worse overall survival and quality of life (QOL). Historically, the only available treatment strategies for MF-related anemia have shown limited efficacy and an increased risk for numerous adverse effects.1,2

In September 2023, the US Food and Drug Administration (FDA) approved momelotinib, an oral inhibitor of JAK1 and JAK2 as well as activin A receptor type 1 (ACVR1), for the treatment of adults with anemia and intermediate or high-risk MF. Momelotinib is currently the only FDA-approved therapy indicated for the treatment of MF patients with anemia.3 In clinical trials, this first-in-class treatment has shown efficacy in treating anemia and other key manifestations of MF.4

Douglas Tremblay, MD, is an assistant professor of medicine at the Icahn School of Medicine at Mount Sinai in New York City, New York, specializing in hematologic malignancies such as myelodysplastic/myeloproliferative overlap syndromes, myeloproliferative neoplasms, and acute myeloid leukemia. He serves as the principal investigator on multiple clinical trials focused on myeloid neoplasms. In this article, Dr Tremblay discusses treatment strategies for MF patients, with a particular focus on those with transfusion-dependent anemia, as well as emerging developments in the MF treatment landscape.

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Promising New Treatment for Myelofibrosis Blood Cancer Using a Combination Targeted Therapy 

By 

An international phase 3 clinical trial of a new drug combination for treating the blood cancer myelofibrosis found that adding a second, experimental drug to standard treatment was more effective than the standard treatment alone. Further, adding the second drug did not significantly increase side effects. Memorial Sloan Kettering Cancer Center (MSK) enrolled the most patients in the trial.

“This is one of the largest myelofibrosis clinical trials to date,” says MSK leukemia specialist Raajit Rampal, MD, PhD, lead author of the study, published March 10 in Nature Medicine. “There is a real unmet need for patients with this disease, and the findings from this trial represent an exciting advance.”

This study looked at adding an experimental drug called pelebresib to the drug ruxolitinib (Jakafi®), which is the current treatment for myelofibrosis. Both drugs are targeted therapies. Pelebrisib blocks the action of proteins involved in inflammation and cancer; ruxolitinib blocks a protein called JAK. This combination approach was based on ongoing research from the lab of MSK leukemia specialist and physician-scientist Ross Levine, MD.

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