This is an open-label study to evaluate the absorption, metabolism, and excretion (AME) of carbon-14 ([14C])-revumenib in participants with acute leukemia.

Participants will be enrolled in this study primarily to complete the 11-day AME portion of the study; participants who are receiving benefit from revumenib may remain on study until progressive disease (PD) or unacceptable toxicity.

Key Inclusion Criteria:

• Males and females (of non-childbearing potential) aged ≥18 years
• Relapsed or refractory acute leukemia, including participants who are MRD-positive by multiparametric flow cytometry or next-generation sequencing, and including participants with isolated extramedullary disease.
• Previously received standard of care therapy
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 2
• Adequate liver and cardiac function
• Fertile males agree to use barrier contraception from the time of enrollment through 120 days after the last study drug dose

Key Exclusion Criteria:

• Active diagnosis of acute promyelocytic leukemia
• White blood cell (WBC) count >25,000/microliters at time of enrollment.
• Detectable human immunodeficiency virus viral load within the previous 6 months
• Hepatitis B or Hepatitis C
• Cardiac, gastrointestinal, or graft-versus-host disease (GVHD)
• History of or any concurrent condition, therapy, laboratory abnormality, or allergy to excipients that might confound the results of the study, interfere with the participant's ability to participate for the full duration of the study, or not be in the best interest of the participant to participate
• Must not be receiving any moderate or strong cytochrome P450 3A4 (CYP3A4) inhibitor/inducers
• Any commercially available or investigational antileukemic therapy other than revumenib except for short-term administration of corticosteroids and/or hydroxyurea for cytoreduction
• Participation in another therapeutic interventional clinical study in which an investigational agent was administered within 30 days before starting revumenib
• Any concurrent systemic treatment to prevent GVHD