Serial blood counts obtained in 2 clinical responders to lestaurtinib. (A) Patient 15, a 74-year-old woman with an ITD mutation, presented with a WCC of 140.7 × 109/L, and was initially cytoreduced with hydroxyurea (HU). HR was achieved on 60 mg of lestaurtinib, with complete clearance of peripheral-blood blasts. There was rapid disease progression after lestaurtinib was withdrawn at day 17 due to the onset of grade 4 fatigue. (B) Patient 19, a 74-year-old man with a D835Y point mutation, presented with a WCC of 42.4 × 109/L and was initially cytoreduced with hydroxyurea. HR was achieved on 60 mg of lestaurtinib, with peripheral-blood blast clearance, transient normalization of neutrophil and platelet counts, and transfusion independence lasting 2 months before disease progression.
