Predictive Factors for Anemia Response to Erythropoiesis-stimulating Agents in Myelofibrosis

Objective: Erythropoiesis-stimulating agents (ESAs) are commonly used to treat the anemia of myelofibrosis (MF), but information on the predictors of response is limited.

Methods: Results of ESA therapy were analyzed in 163 MF patients with severe anemia, most of whom had inadequate erythropoietin (EPO) levels (<125 U/L) at treatment start.

Results: According to the revised criteria of the International Working Group for Myelofibrosis Treatment and Research, anemia response was achieved in 86 patients (53%). Median response duration was 19.3 months. In multivariate analysis, baseline factors associated with a higher response rate were female sex (P=.007), leukocyte count ≥10×10 /L (P=.033), and serum ferritin <200 ng/mL (P=.002). Patients with 2 or 3 of the above features had a significantly higher response rate than the remainder (73% vs 28%, respectively; P<.001). Over the 373 patient-years of follow-up on ESA treatment, nine patients developed thrombotic complications (six arterial, three venous), accounting for 2.41 events per 100 patient-years. Survival time from ESA start was longer in anemia responders than in non-responders (P=.011).

Conclusion: Besides the already established predictive value of EPO levels, these data can help to identify which MF patients are more likely to benefit from ESA treatment.