Inclusion Criteria

1. First allogeneic HSCT, in ≤ CR2, and MRD negative prior to transplant (including
matched sibling, MUD with at least 6 of 8 HLA markers, or haploidentical with at least
5 of 10 HLA markers) as:

- Adjuvant therapy for AML (Group 1) at 90 days (±10 days) post-HSCT defined as
patients with CRMRD; or

- Treatment for refractory/relapsed AML (first relapse post-HSCT) when disease
occurs after transplant (Group 2) defined as

- First relapse (MRD+ or frank relapse) post-HSCT

- Patients in Arm 1B (SOC) who experience first relapse (MRD+ or frank
relapse) post HSCT

- Safety Lead-in defined as patients who fit all the criteria for Group 2 only

2. Are ≥18 years of age

3. Karnofsky/Lansky score of ≥60

4. Life expectancy ≥12 weeks

5. Adequate blood, liver, and renal function

- Blood: Hemoglobin ≥7.0 g/dL (can be transfused)

- Liver: Bilirubin ≤2X upper limit of normal; aspartate aminotransferase ≤3X upper
limit of normal

- Renal: Serum creatinine ≤2X upper limit of normal or measured or calculated
creatinine clearance ≥45mL/min

7. Patients are allowed to be on experimental conditioning regimens prior to transplant if
no planned maintenance therapy post-transplant.

8. In Group 2, patients may receive bridging therapy at the investigators' discretion in
situations where MT-401 is not ready for administration or the treating physician believes
the patient would benefit

Exclusion Criteria

1. Clinically significant or severely symptomatic intercurrent infection

2. Pregnant or lactating

3. For Group 1, anti-neoplastic therapy after HSCT and prior to or during dosing of
MT-401

4. For Group 2, concomitant anti-neoplastic therapy during or after dosing of MT-401

5. Evidence of acute or chronic GVHD ≥Grade 2 (exception: acute or chronic Grade 2 GVHD
of skin allowed if stable) within one week prior to receiving MT-401

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

Eligibility last updated 12/27/22. Questions regarding updates should be directed to the study team contact.