APTO-253 is a novel small molecule that inhibits expression of the c-Myc oncogene, leading to cell cycle arrest and programmed cell death (apoptosis) in human-derived solid tumor and hematologic cancer cells. Likewise, in nonclinical pharmacology studies APTO-253 demonstrates in vivo anti-tumor activity against xenograft models of solid tumors and hematologic cancers, with acute myeloid leukemia (AML) cells exhibiting a particular sensitivity to APTO-253. A Phase 1 study with APTO-253 was completed and demonstrated modest clinical activity in patients with advanced solid tumors, and APTO-253 is currently under evaluation in a Phase 1b trial in patients with acute leukemias (including AML) and high-risk MDS. The original formulation of APTO-253 led to filter-clogging in the Phase 1b trial, and since that time Aptose has developed an improved formulation speculated to avoid such events moving forward. Further, manufacturing delays of a clinical supply with the new drug product formulation led to delays in the Phase 1b clinical trial, and Aptose is now performing studies to determine the root cause and corrective action of the manufacturing delay. It is likely that these issues will be resolved during the second half of 2017 such that the clinical supply of APTO-253 can be manufactured with confidence and the program can be positioned for a return to the clinical trial and/or partnering.