Navigating the Expanding Landscape of Myelofibrosis Treatment

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, splenomegaly, debilitating constitutional symptoms, and cytopenias.¹ Patients often experience profound fatigue, night sweats, early satiety, and weight loss, with the disease carrying a median survival that varies widely depending on risk category. Management of MF is risk-adapted, guided by validated prognostic scoring systems, such as the Dynamic International Prognostic Scoring System (DIPSS), that stratify patients as lower or higher risk to determine prognosis and inform treatment selection.² While the treatment landscape has evolved substantially over the past decade, optimizing therapy for individual patients remains a complex clinical challenge.

Ruxolitinib: The Established Standard of Care

For more than a decade, ruxolitinib (Jakafi; Incyte Corporation), an oral JAK1/JAK2 inhibitor, has served as the cornerstone of pharmacologic treatment for intermediate-2 and high-risk MF.³ Its approval in 2011 by the FDA was based on data from the landmark phase 3 COMFORT-II trial (NCT00934544)⁴, which demonstrated significant spleen volume reduction and symptom improvement compared with placebo or best available therapy. Real-world data from more than 4500 patients have since reinforced the drug’s effectiveness, confirming reductions in splenomegaly and improved overall survival, consistent with trial findings.³ Transient anemia and thrombocytopenia are among the most commonly observed adverse effects, though these rarely require permanent discontinuation. Ruxolitinib also remains the only JAK inhibitor with a clearly demonstrated survival benefit in MF, underscoring its continued role as the preferred frontline agent for most patients.

Despite its clinical utility, ruxolitinib carries notable limitations. Treatment-emergent cytopenias can constrain dosing, potentially compromising efficacy. Approximately 70% to 80% of patients develop anemia by the end of frontline therapy with JAK inhibitors, and nearly half of those require transfusions.⁵ After 2 to 3 years, some patients develop drug resistance, likely due to the limited impact on driver mutation burden. These challenges highlight the need for additional therapeutic strategies, particularly for patients with baseline cytopenias or those who lose response over time.

Addressing Cytopenias: Ruxolitinib Use in Anemia and Thrombocytopenia

A significant proportion of patients present with anemia or thrombocytopenia at diagnosis, historically limiting ruxolitinib use. However, findings from a retrospective real-world analysis have shown that most patients with hemoglobin levels less than 10 g/dL or platelet counts at or below 100 × 10⁹/L at diagnosis were able to maintain ruxolitinib doses of 10 mg twice daily or higher for nearly 2 years, with improved spleen size and symptom control observed in the majority.³ These findings affirm the clinical viability of ruxolitinib across a broader patient population than originally captured in pivotal trials, though dose optimization and careful monitoring are essential.

Role of Transplantation and Emerging Therapies

Allogeneic hematopoietic stem cell transplantation remains the only potentially curative modality for MF but is limited by high procedural morbidity and mortality, restricting its application to carefully selected, fit patients with higher-risk disease.¹ For those not eligible for transplantation, the goal of therapy shifts toward symptom management, spleen reduction, and preservation of quality of life. As the therapeutic pipeline continues to evolve—with combination strategies involving ruxolitinib plus novel agents such as navitoclax and luspatercept (Reblozyl; Celgene Corporation) under active investigation—pharmacists and clinicians are positioned to play a critical role in supporting individualized treatment decisions, monitoring adverse effects, and educating patients on the growing range of available options.

References

1. Wei CT, Than H, Huang FJ, Billa G, Lee LH. Managing myelofibrosis: matching advances in treatments with clinical unmet needs. Hematol Oncol. 2025;43(suppl 1):e70053. doi:10.1002/hon.70053

2. Stuckey R, Segura Díaz A, Gómez-Casares MT. Myelofibrosis: treatment options after ruxolitinib failure. Curr Oncol. 2025;32(6):339. doi:10.3390/curroncol32060339

3. Al-Ali HK, Gerds AT, Grunwald MR, Yu J. A review of real-world experience with ruxolitinib for myelofibrosis. Clin Lymphoma Myeloma Leuk. 2025;25(5):e262-e281. doi:10.1016/j.clml.2024.12.013

4. Controlled myelofibrosis study with oral Janus-associated kinase (JAK) inhibitor treatment-II: the COMFORT-II trial. ClinicalTrials.gov. https://clinicaltrials.gov/study/NCT00934544

5. Martino M, Pitea M, Sgarlata A, et al. Treatment strategies used in treating myelofibrosis: state of the art. Hematol Rep. 2024;16(4):698-713. doi:10.3390/hematolrep16040067