Imatinib, the first approved drug in this category, is an adenosine triphosphate, competitive inhibitor of KIT, PDGFRA, BCR-ABL, and ABL tyrosine kinases, which was already used in the treatment of patients with chronic myeloid leukemia (CML) who bear the BCR-ABL fusion gene [3, 16]. The gene discussed is PDGFRA; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.