Dendritic Cell/AML Fusion Cell Vaccine Following Allogeneic Transplantation in AML Patients

This research study is studying a cancer vaccine called Dendritic Cell/AML Fusion vaccine (DC/AML vaccine) as a possible treatment for Acute Myelogenous Leukemia (AML). The interventions involved in this study are: * Dendritic Cell/AML Fusion vaccine (DC/AML vaccine) * Decitabine, a chemotherapy drug

Inclusion Criteria: * Patients with AML who have undergone AML cell harvest and cryopreservation as per protocol 16-593 or companion protocol 18-232. * Patients must have had a minimum of 5x107 cells cryopreserved. * Patients must be day 25-45 following allogeneic transplantation from either: * Group A: HLA 8/8 or 7/8 matched related donor or HLA 8/8 matched unrelated donor, as determined by antigen or allele level typing at HLA A,B,C, and HLA DRB1. OR * Group B: Haplo-identical donor * Patients must be ≥ 18 years old * ECOG performance status ≤2 (Appendix A) * Participants must have normal organ and marrow function as defined below: * Total bilirubin ≤ 2.0 mg/dL (unless patient has Gilbert's disease) * AST(SGOT)/ALT(SGPT) ≤ 3 × institutional upper limit of normal * Creatinine ≤ 2.0 mg/dl * Absolute neutrophil count \> 1000 * Platelet count \> 50,000 * The effects of DC/AML fusion cells on the developing human fetus are unknown. For this reason, women of child-bearing potential and men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. * No evidence of ongoing grade 2 or higher aGVHD * Must be on prednisone \60% * Resolution of all transplant related grade III-IV toxicity as per CTC criteria 4.0 * Complete remission defined by absence of circulating blasts and less than 5% blasts in the bone marrow * Ability to understand and the willingness to sign a written informed consent document. Eligibility Prior to Initiating Vaccination (Groups A and B) * Assessments to be done between Day 45-75 post-transplant. * At least 2 doses of fusion vaccine were produced * No ongoing grade II-IV acute GVHD * Prednisone requirement of \< 20mg a day or steroid equivalent * Participants must have normal organ and marrow function as defined below: * Total bilirubin ≤ 2.0 mg/dL (unless patient has Gilbert's disease) * AST(SGOT)/ALT(SGPT) ≤ 3 × institutional upper limit of normal * Creatinine ≤ 2.0 mg/dl * Absolute neutrophil count \> 1000 * Platelet count \> 50,000 * No uncontrolled acute infection * No CTCAE grade ≥ 3 non-hematologic toxicity * No serious intercurrent illness such as active acute infection, or significant cardiac disease characterized by clinically significant arrhythmia, active ischemic coronary disease or symptomatic congestive heart failure. * Participants must be in a complete remission Pre-Treatment Criteria Prior to Decitabine (Group A Cohort 2) * Assessments to be done within 3 days prior to initiation of therapy. * Participants must have normal organ and marrow function as defined below: * Total bilirubin ≤ 2.0 mg/dL (unless patient has Gilbert's disease) * AST(SGOT)/ALT(SGPT) ≤ 3 × institutional upper limit of normal * Creatinine ≤ 2.0 mg/dl * Absolute neutrophil count \> 1000 * Platelet count \> 50,000 Exclusion Criteria: * Because of compromised cellular immunity, patients with a known history of HIV are excluded * Leukemia with active CNS involvement * Patients must not be pregnant. All premenopausal patients will undergo pregnancy testing. Men will agree to not father a child while on protocol treatment. Men and women will practice effective birth control while receiving protocol treatment. * Participants may not be receiving any other Non-FDA approved study agents at the start of vaccination * Uncontrolled intercurrent illness including uncontrolled active infection, symptomatic congestive heart failure, unstable angina pectoris, clinically significant cardiac arrhythmia, or psychiatric illness that would limit compliance with study requirements. * Autoimmune or inflammatory disorders requiring active treatment with systemic steroids or immunosuppressive therapy limited to the following: * GI Disorders: (including inflammatory bowel disease \[e.g., ulcerative colitis, Crohn's disease\] * Systemic lupus erythematosus * Wegener's syndrome \[granulomatosis with polyangiitis\] * Myasthenia gravis * Graves' disease * Rheumatoid arthritis * Hypophysitis * Uveitis