We recently synthesized and discovered a new compound (17f) that inhibits STAT5 phosphorylation and transcriptional activity in various CML and AML cells, without detectable effects on other signal transduction molecules, such as STAT3 and the protein kinases ERK1/2 and AKT [23]. The gene discussed is STAT5A; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.