Interim Analysis Confirms Efficacy, Tolerability of Ruxolitinib in Myelofibrosis

By Melissa Badamo - Last Updated: October 13, 2023

A study published in Annals of Hematology confirmed the efficacy and tolerability of ruxolitinib treatment in patients with primary myelofibrosis (MF) who are JAKi-naive or pretreated with JAKi.

This two-arm, open-label study is an interim analysis of JAKoMo, a prospective, noninterventional, phase IV study in MF and the first large, real-world cohort to be reported in the European Union.

JAKoMo included 928 patients from 122 German centers who were either JAKi-naive (50%) or pretreated with JAKi (50%) and had a diagnosis of primary MF.

The study, conducted by Steffen Koschmieder, MD, Ph.D., and colleagues, evaluated the 464 JAKi-naive patients (median age, 73 years).

For a median duration of 1.5 years, patients received ruxolitinib therapy at either 40 mg/day (25.4%), 30 mg/day (39.5%), 20 mg/day or less (35.1%), or 10 mg/day or less (20.8%), with a median dosage of 23.77 mg/day. Patients were observed for up to 36 months.

Of the patients, 82.5% experienced rapid (<1 month) significant decreases in palpable spleen size. After two months of ruxolitinib therapy, median spleen length was reduced 42% from 13.9 cm BCM at baseline to 8 cm and remained stable throughout the trial.

Patients also saw a significant improvement in symptom burden during ruxolitinib treatment, while Eastern Cooperative Oncology Group (ECOG) performance status showed a trend toward improvement.

The 24-month overall survival (OS) was 81.2%. Of the patients, 80 (17.2%) died during the study, 25 (5.4%) terminated the study due to disease progression, and seven (1.5%) terminated the study because of transformation to acute myeloid leukemia (AML).

86.9% of patients experienced at least one adverse events (AEs), most commonly anemia (31.2%) and thrombocytopenia (28.6%), while 51.3% of patients experienced at least one severe adverse events (most commonly anemia).

Overall, researchers concluded, “This large analysis of [ruxolitinib] treatment in therapy-naive MF patients confirms feasibility in the real-world setting and demonstrates efficacy and tolerability comparable to those observed in the more selected JUMP and COMFORT-II drug approval trial populations.”


Koschmieder S, Isfort S, Schulte C, et al. Real-world analysis of ruxolitinib in myelofibrosis: interim results focusing on patients who were naïve to JAK inhibitor therapy treated within the JAKoMo non-interventional, phase IV trial. Ann Hematol. 2023; doi:10.1007/s00277-023-05458-1

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