In JAK2 inhibitor-naïve patients13, MMB was compared to ruxolitinib and among patients completing 24 weeks of therapy, spleen response rates were similar (26.5% vs 29%) while anemia response rates were superior with MMB (transfusion-independence rate of 66.5% vs 49.3%) and symptoms response rates with ruxolitinib (42.2% vs 28.4%); grade 3/4 anemia occurred more frequently with ruxolitinib (23% vs 6%) while other AEs were reported to be similar. Here, JAK2 is linked to anemia.