Venetoclax and Lintuzumab-Ac225 in AML Patients

Inclusion Criteria: 1. Refractory or relapsed AML which will include: 1. Refractory disease will be defined as at least 1 prior treatment with no remission. 2. Relapsed disease will be defined as 5% or more blasts in bone marrow seen after remission. 3. Patients with AML arising from myelodysplastic syndromes (including CMML) or myeloproliferative neoplasms (secondary AML, ts-AML) are also eligible. 2. Circulating blast count ≤ 200/μL within 10 days prior to first cycle of treatment. Hydroxyurea should be used to keep the peripheral blast count ≤ 200/μL until the first day of protocol treatment, to the extent that this is possible 3. ECOG ≤ 2 4. Estimated creatinine clearance ≥ 50 mL/min 5. AST and ALT ≤ 3.0 x ULN 6. Bilirubin ≤ 3.0 x ULN Exclusion Criteria: 1. Active CNS Leukemia. 2. Known HIV infection or known hepatitis B or hepatitis C infection (with a detectable viral load). 3. Participant has received strong and/or moderate CYP3A inducers within 7 days prior to the initiation of study treatment. 4. Secondary refractory AML (e.g., treated for current relapse without achieving remission); a. With the exception that single agent FLT3 inhibitors, IDH1/IDH2 inhibitors are allowed for current relapse without achieving remission. 5. Have received prior radiation to maximally tolerated levels to any critical normal organ. 6. Clinically significant cardiac disease. 7. Active, uncontrolled serious infection. 8. Have other non-myeloid malignancy within 2 years of entry (with exceptions). 9. Psychiatric disorder that would preclude study participation 10. Previous solid organ transplant (prior treatment with SCT is allowed but not if patient has GVHD or is still receiving immunosuppression/GVHD therapy).