IDH1 and Splenomegaly: Patients who received non-intensive approaches at first R/R episode were more likely to have the following characteristics at initial diagnosis compared with those receiving intensive salvage regimens: older age (72 years; p < 0.0001), more secondary AML (27%; p = 0.0007), less extramedullary disease such as hepatomegaly or splenomegaly (15%; p = 0.003), lower WBC (26 × 109/L; p = 0.02), lower FLT3-ITD allelic ratio (0.4; p = 0.0004) and more isocitrate dehydrogenase (IDH) mutations (14%; p = 0.003; Table 2).