Safety and Tolerability Evaluation of MaaT033

Inclusion Criteria: 1. Male or Female 2. Age ≥ 18 years 3. Patients diagnosed with AML defined according to WHO 2016 criteria with ≥20% leukemic blasts in the bone marrow or with high- risk myelodysplastic syndrome, receiving intensive chemotherapy 4. Patients healthy enough to likely receive their consolidation or second cycle of chemotherapy after induction chemotherapy 5. Patients healthy enough to likely receive HSCT 6. Informed written consent 7. Patient recovered from neutropenia Exclusion Criteria: 1. Acute promyelocytic leukemia (AML-M3) 2. AML secondary to myeloproliferative disorder or chronic myelomonocytic leukemia (CMML) 3. Acute myeloid leukemia BCR-ABL1+ 4. Active CNS leukemia 5. Patients with a life expectancy of \<70 days according to investigator's opinion, or subject to therapeutic limitations 6. Confirmed or suspected intestinal ischemia 7. Confirmed or suspected toxic megacolon or gastrointestinal perforation 8. Active uncontrolled infection according to the attending physician 9. Any gastro-intestinal bleeding in the past 3 months 10. Any history of gastro-intestinal surgery in the past 3 months 11. Any history of inflammatory bowel disease 12. Any counter-indication to swallow capsules 13. Enrollment in another trial that may interfere with this study 14. Known allergy or intolerance to trehalose, maltodextrin or PEG 15. Women of childbearing potential without efficient contraceptive protection 16. Pregnant or breastfeeding 17. Patients with EBV-negative serology 18. Subject who, in the judgment of the Investigator, is likely to be non-compliant or uncooperative during the study, or unable to cooperate because of a language problem, poor mental development; 19. Exclusion period of a previous study 20. Administrative or legal supervision 21. Confirmed positive result to SARS-CoV-2 nasopharyngeal test at screening