Ruxolitinib Remains Cornerstone of Myelofibrosis Treatment as New Combinations Are Studied

Ruxolitinib remains the cornerstone of pharmacologic treatment for intermediate-2 and high-risk myelofibrosis, with phase 3 COMFORT trials demonstrating significant spleen volume reduction and symptom improvement compared with placebo or best available therapy. Real-world data across more than 4500 patients have reinforced the drug's effectiveness, confirming reductions in splenomegaly and improved overall survival consistent with trial findings.

Myelofibrosis is a chronic myeloproliferative neoplasm characterized by progressive bone marrow fibrosis, splenomegaly, debilitating constitutional symptoms, and cytopenias. Management 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.

For more than a decade, ruxolitinib, an oral JAK1/JAK2 inhibitor, has served as the standard of care. Its 2011 FDA approval was based on the landmark phase 3 COMFORT trials. 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 clearly demonstrated survival benefit in myelofibrosis.

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. After 2 to 3 years, some patients develop drug resistance, likely due to limited impact on driver mutation burden.

A significant proportion of patients present with anemia or thrombocytopenia at diagnosis, historically limiting ruxolitinib use. Retrospective real-world analysis showed that most patients with hemoglobin 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.

Allogeneic hematopoietic stem cell transplantation remains the only potentially curative modality for myelofibrosis but is limited by high procedural morbidity and mortality, restricting its application to carefully selected, fit patients with higher-risk disease. For patients not eligible for transplantation, the goal of therapy is symptom management, spleen reduction, and preservation of quality of life. Combination strategies involving ruxolitinib plus novel agents such as navitoclax and luspatercept are under active investigation.