Estimated probabilities of splenic response using the Early and Late models. To demonstrate how the early (left panel) and late (right panel) models can be used to predict splenic response, plots based on increasing spleen size are shown for a hypothetical patient treated with JAK-inhibitor therapy. Two possible WBC counts were inputted (blue circles=7*109/L WBC; yellow triangles=35*109/L WBC). All other patient characteristics are fixed: 70 year old male diagnosed 140 weeks ago treated at 100% of the recommended phase 2 dose, platelets 210*109/L, Hgb 10.7 g/dL, requiring transfusions at baseline, and European Consensus Criteria MF-3.