A Phase 1/2 Study of SL-401 as Consolidation Therapy for Adult Patients With Adverse Risk Acute Myeloid Leukemia in First CR, and/or Evidence of Minimal Residual Disease (MRD) in First CR

• The patient has a diagnosis of AML according to World Health Organization (WHO) criteria.

• The patient received any induction chemotherapy regimen and may have received post-remission consolidation therapy prior to screening.

• The patient has achieved a first or second CR or CRi. For patients without evidence of MRD in CR/CRi, CR (or CRi) must have been initially identified within 12 months prior to screening.

• OR The patient has achieved first or second CR or CRi with evidence of MRD as determined locally at least 6 months post stem cell transplant without evidence of acute or chronic graft-versus-host disease post-transplant and has not received immunosuppressant therapy for at least 14 days prior to SL-401 therapy.

• The patient has adverse risk disease or AML for which there is otherwise a substantial risk of relapse, which includes but is not limited to: adverse karyotype, FLT3 internal tandem duplication (ITD) mutation, history of antecedent hematologic disorder (AHD), therapy-related AML, history of requiring more than 1 cycle of intensive induction chemotherapy to achieve first remission, and/or presence of persistent MRD (detected by cytogenetics, molecular markers, or flow cytometry) at any point after the initial induction cycle.

• For patients enrolling in Stage 2, the bone marrow evaluation determined locally within the previous 6 months indicates the presence of MRD.

• The patient is not considered to be an immediate candidate for allogeneic stem cell transplant as determined by the investigator.

• The patient is ≥18 years old.

• The patient has an Eastern Cooperative Oncology Group (ECOG) performance score (PS) of 0-2.

• The patient has adequate organ function, including cardiac, renal, and hepatic function:

‣ Left ventricular ejection fraction (LVEF) ≥institutional lower limit of normal as measured by multigated acquisition scan (MUGA) or 2-dimensional (2-D) echocardiography (ECHO) within 28 days prior to start of therapy and no clinically significant abnormalities on a 12-lead electrocardiogram (ECG)

⁃ Serum creatinine ≤1.5 mg/dL

⁃ Serum albumin ≥3.2 g/dL in the absence of receipt of (IV) albumin within the previous 72 hours.

⁃ Bilirubin ≤1.5 mg/dL

⁃ Aspartate transaminase (AST) and alanine transaminase (ALT) ≤2.5 × the upper limit of normal (ULN)

⁃ Creatine phosphokinase (CPK) ≤2.5 × the ULN.

⁃ The patient has adequate bone marrow reserve:

⁃ • Absolute neutrophil count (ANC) \> 0.5 × 10\^9/L

⁃ The patient is a woman of child bearing potential (WOCBP) who has had a negative serum or urine pregnancy test within 1 week prior to SL-401 treatment (intervals shorter than 1 week are acceptable if required by institutional guidelines).

⁃ A written and voluntarily signed informed consent must be obtained from the patient or legally authorized representative, in accordance with local regulations, before the initiation of any study related procedures. The patient or legally authorized representative must be able to read and understand the informed consent form (ICF).

⁃ The patient is able to adhere to the study visit schedule and other protocol requirements, including follow-up for survival assessment.

⁃ The patient (male and female) agrees to use acceptable contraceptive methods for the duration of time on the study, and continue to use acceptable contraceptive methods for 2 months after the last infusion of SL-401.