A Phase 1/2 Study of Bleximenib in Participants With Acute Leukemia (cAMeLot-1)

The purpose of this study is to determine the recommended Phase 2 dose(s) (RP2D\[s\]) of bleximenib in phase 1 Part 1 (Dose Escalation) and to determine the safety and tolerability at RP2D in Phase 1 Part 2 (Dose expansion). The purpose of the Phase 2 part of the study is to evaluate the efficacy of bleximenib at the RP2D.

Inclusion Criteria: Phase 1: * Age 2 years to less than (\=40 mL/min per the CKiD (Chronic Kidney Disease in Children) Schwartz formula * Eastern Cooperative Oncology Group (ECOG) performance status grade of 0, 1 or 2. Pediatric participants only: Performance status \>=70 by Lansky scale (for participants \< 16 years of age) or \>=70 Karnofsky scale (for participants \>=16 years of age) * A female of childbearing potential must have a negative highly sensitive serum beta-human chorionic gonadotropin at screening and within 48 hours prior to the first dose of study treatment * Participant must agree to all protocol required contraception requirements and avoid sperm or egg donations or freezing for future reproductive use while on study and for 90 days (males) or 6 months (females) after the last dose of study treatment Exclusion Criteria: * Acute promyelocytic leukemia, diagnosis of Down syndrome associated leukemia or juvenile myelomonocytic leukemia according to World Health Organization (WHO) 2016 criteria * Active central nervous system (CNS) disease * Prior solid organ transplantation * QTc according to Fridericia's formula (QTcF) for males \>= 450 millisecond (msec) or for females \>= 470 msec. Participants with a family history of Long QT syndrome are excluded * Exclusion criteria related to stem cell transplant: a. Received prior treatment with allogenic bone marrow or stem cell transplant \