The U.S. FDA has granted Orphan Drug Designation to APTO-253, an investigational drug of Aptose Biosciences, a Ontario, Canada based biotechnology company for the treatment of acute myeloid leukemia (AML). AML is a rare form of cancer derived from myeloid stem cells in the bone marrow. It is a challenging blood cancer to treat and currently there are few treatment options. It has been shown in the literature that epigenetic suppression of the Krüppel-like factor 4 (KLF4) gene may be a key oncogenic event leading to AML. APTO-253 is a targeted inducer of the KLF4 tumor suppressor gene. Preclinical studies have demonstrated favorable outcomes with APTO-253 against AML cells. According to Aptose Biosciences, APTO-253 is currently in a Phase Ib clinical trial in patients with relapsed or refractory hematologic malignancies.