Study of Revumenib, Azacitidine, and Venetoclax in Pediatric and Young Adult Patients With Refractory or Relapsed Acute Myeloid Leukemia

This is a research study to find out if adding a new study drug called revumenib to commonly used chemotherapy drugs is safe and if they have beneficial effects in treating patients with acute myeloid leukemia (AML) or acute leukemia of ambiguous lineage (ALAL) that did not go into remission after treatment (refractory) or has come back after treatment (relapsed), and to determine the total dose of the 3-drug combination of revumenib, azacitidine and venetoclax that can be given safely in participants also taking an anti-fungal drug. Primary Objective * To determine the safety and tolerability of revumenib + azacitidine + venetoclax in pediatric patients with relapsed or refractory AML or ALAL. Secondary Objectives * Describe the rates of complete remission (CR), complete remission with incomplete count recovery (CRi), and overall survival for patients treated with revumenib + azacitidine + venetoclax at the recommended phase 2 dose (RP2D).