Phase 1 Study Evaluating ZEN003365 in Relapsed/Refractory Lymphoproliferative Malignancies or Relapsed/Refractory AML

Inclusion Criteria: Dose Escalation and Expansion Stages: * ECOG performance status ≤ 1 for LPM patients, ≤ 2 for AML patients * Age 18 years or older * Adverse events (AEs), except for alopecia, from any previous treatments must have recovered to eligibility levels from prior toxicity * Adequate renal, hepatic and coagulation function, as specified per protocol * Written informed consent granted prior to any study-specific screening procedures LPM Patients: * Histologically confirmed lymphoproliferative malignancy * Have received prior protocol-specified disease-dependent prior treatments * Have measurable disease * Platelets ≥ 75,000/µL (≥50,000/µL if bone marrow involvement), absolute neutrophil count (ANC) ≥ 1,000/ µL, and hemoglobin (Hgb) ≥ 8 g/dL * Patients must have been off previous anticancer therapy for at least 3 weeks or 5 half-lives, whichever is longer, and the subject must have recovered to eligibility levels from prior toxicity AML: * Refractory or relapsed AML patients, without curative intent, e.g., not a stem cell transplant candidate * Any prior chemotherapy must have been completed ≥ 2 weeks, any therapy with biologics must have been completed ≥ 4 weeks prior to day 1 of study treatment, and the participant must have recovered to eligibility levels from prior toxicity * Blast count ≤ 10,000/µL prior to initiation of therapy Exclusion Criteria Dose Escalation and Expansion Stages: * Prior exposure to a BET inhibitor * Prior allogeneic hematopoietic cell transplant * Chronic graft versus host disease * Known, active fungal, bacterial, and/or viral infection * Uncontrolled autoimmune hemolytic anemia or thrombocytopenia * Current subdural hematoma * CNS or leptomeningeal metastases * Requirement for medications or agents known to be sensitive CYP3A4 substrate drugs, CYP3A4 substrate drugs with a narrow therapeutic range or to be strong inhibitors/inducers of CYP3A4 * Requirement for immunosuppressive agents * Evidence of significant cardiovascular disease or significant screening ECG abnormalities * Any medical conditions that, in the Investigator's opinion, would impose excessive risk to the patient. AML patients: * Acute promyelocytic leukemia (APL) * Chronic myeloid leukemia (CML) in blast crisis