Fedratinib Improves Overall and Landmark Survival Rates in Patients Diagnosed with Myelofibrosis and Prior Ruxolitinib Treatment

Myelofibrosis (MF) is a cancer of the bone marrow typically characterized by scarring, anemia, and enlargement of the spleen. Driven by dysregulation of Janus kinase, JAK inhibitors such as ruxolitinib (RUX) have proven useful in treating MF. RUX is a JAK1/2 inhibitor approved by the FDA for treatment of intermediate- or high-risk myelofibrosis. Despite its approval, RUX is not well-tolerated and many patients must discontinue its use due to lack or loss of response or development of cytopenia. Fedratinib (FEDR), a selective JAK2 inhibitor, was recently approved in the United States in 2019, but its effectiveness in a real-world setting in patients with MF previously treated with RUX has not been evaluated. Therefore, the present study evaluated 229 patients with MF who had been treated with RUX with and without FEDR treatment.

Enrolled participants (n = 229) were grouped by FEDR treatment (n = 70) or no FEDR (n = 159). The group that did not receive FEDR was further stratified by timing of RUX treatment (before 2019 approval [n = 50] vs after 2019 approval [n = 109]). Participants were on average aged 70 years, primarily female, and white. Median duration of FEDR therapy was 3.7 months (range, 0-12.2 months) at an initial dose of 400 mg/day (47%) or 200 mg/day (21%). In the FEDR treatment group, 90% of patients had Eastern Cooperative Oncology Group performance status 0 or 1, compared with 74% in the non-FEDR group. Median overall survival was not reached in the FEDR treatment group and was 17 months in the non-FEDR patients. Landmark survival at 3 months and 12 months for the FEDR treatment group was 91% and 72%, respectively, and in the non-FEDR group it was 72% and 54%, respectively. In the non-FEDR group that received RUX after 2019, landmark survival at 3 months was 75% and at 12 months was 48% of patients.

These data indicate that for up to 1 year after baseline, treatment with FEDR demonstrated improved survival rates in patients previously treated with RUX compared with similar patient demographics who did not receive FEDR. In summary, the evidence suggests that FEDR may offer substantially improved survival probability in patients receiving post-RUX therapy for primary MF.


  • Passamonti F, Do Q, Lou Y, et al. Real-world outcomes with fedratinib therapy in patients who discontinued ruxolitinib for primary myelofibrosis. American Society of Hematology Annual Meeting and Exposition; December 11-14, 2021. Abstract 3645.

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