A Phase 1/2 Study of Bleximenib in Participants With Acute Leukemia

Inclusion Criteria:

Phase 1:

• Relapsed or refractory (R/R) acute leukemia and has exhausted, or is ineligible for,available therapeutic options

• Participants greater than or equal (>=)12 and less than (<) 18 years of age are onlyeligible for the Phase 1 adolescent cohort

• Acute leukemia harboring histone-lysine N-methyltransferase 2A (KMT2A),nucleophosmin 1 gene (NPM1) or nucleoporin 98 gene or nucleoporin 214 gene (NUP98 orNUP214) alterations

Phase: 2

• Participants greater than 18 years are eligible

• Must have had an initial diagnosis of acute myeloid leukemia (AML) per the WHO 2022classification criteria and have relapsed/refractory disease

• AML harboring KMT2A-r (gene rearrangement/translocation) or NPM1 mutations only

For Both Phase 1 and 2:

• Pretreatment clinical laboratory values meeting the following criteria: (a)Hematology: white blood cell (WBC) count less than or equal to (<=) 20*10^9/liter (L) and (b) renal function; Estimated or measured glomerular filtration rate greaterthan or equal to (>=) 50 milliliter per minute (mL/min) per four variable modifieddiet in renal disease (MDRD) equation

• Eastern Cooperative Oncology Group (ECOG) performance status grade of 0, 1 or 2.Adolescent participants only: Performance status >=70 by Lansky scale (forparticipants less than [<]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 serumbeta-human chorionic gonadotropin at screening and within 48 hours prior to thefirst dose of study treatment

• Participant must agree to all protocol required contraception requirements and avoidsperm or egg donations or freezing for future reproductive use while on study andfor 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 orjuvenile myelomonocytic leukemia according to World Health Organization (WHO) 2016criteria

• Active central nervous system (CNS) disease

• Prior solid organ transplantation

• QTc according to Fridericia's formula (QTcF) for males >= 450 millisecond (msec) orfor females >= 470 msec. Participants with a family history of Long QT syndrome areexcluded

• Exclusion criteria related to stem cell transplant: a. Received prior treatment withallogenic bone marrow or stem cell transplant <=3 months before the first dose ofstudy treatment; b. Has evidence of graft versus host disease; c. Received donorlymphocyte infusion <=1 month before the first dose of study treatment; d. Requiresimmunosuppressant therapy (exception: daily doses <=10 milligrams (mg) prednisone orequivalent are allowed for adrenal replacement)

• Prior cancer immunotherapy within 4 weeks prior to enrollment or blinatumomab within 2 weeks prior to enrollment. Additional prior cancer therapies must not be givenwithin 4 weeks prior to enrollment or 5 half-lives of the agent (whichever isshorter)