Regorafenib in Combination With Venetoclax and Azacitidine for the Treatment of Patients With Relapsed or Refractory Acute Myeloid Leukemia

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative * Age: ≥ 18 years * Eastern Cooperative Oncology Group (ECOG) ≤ 2 * Patients with histologically confirmed AML, according to World Health Organization (WHO) criteria, with refractory/relapsed (R/R) disease who are ineligible for therapies known to be effective for treatment of their AML * Patients with extramedullary disease may be included if they also have marrow involvement * Patients with acute promyelocytic leukemia (APL) will not be eligible * Patients with R/R myelodysplastic syndrome (MDS)/AML, as defined by the presence of 10 - 19% blasts, are also eligible at the discretion of the principal investigator (PI) * Fully recovered from the acute toxic effects (except alopecia) to ≤ grade 1 to prior anti-cancer therapy * Ability to swallow pills * White blood cells (WBC) ≤ 25 x 10\^9/L prior to initiation of study therapy. Cytoreduction with hydroxyurea prior to treatment and/or during cycle 1 may be required (To be performed within 14 days prior to day 1 of protocol therapy) * Total bilirubin ≤ 1.5 x upper limit of normal (ULN) (unless has Gilbert's disease) (To be performed within 14 days prior to day 1 of protocol therapy) * Aspartate aminotransferase (AST) ≤ 3.0 x ULN (To be performed within 14 days prior to day 1 of protocol therapy) * Alanine aminotransferase (ALT) ≤ 3.0 x ULN (To be performed within 14 days prior to day 1 of protocol therapy) * Creati…