A First in Human Study of the Menin-KMT2A (MLL1) Inhibitor JNJ-75276617 in Participants with Acute Leukemia

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 with a body weight of >= 40 kg are only eligible 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 or NUP214) alterations

Phase: 2

• Participants greater than 18 years are eligible
• Must have had an initial diagnosis of acute myeloid leukemia (AML) per the WHO 2022 classification criteria.
• 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 renal function; Estimated or measured glomerular filtration rate greater than or equal to (>=) 50 milliliter per minute (mL/min) per four variable modified diet 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 (for participants less than [<]16 years of age) or >=70 Karnofsky scale (for participants >=16 years of age)
• A participant 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
• A participant must agree to all the following during the study and for 90 days after the last dose of study treatment: (a) wear a condom when engaging in any activity that allows for passage of ejaculate to another person; (b) not to donate sperm or freeze for future use for the purpose of reproduction. In addition, the participant should be advised of the benefit for a partner to use a highly effective method of contraception as condom may break or leak

• 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

allogenic bone marrow or stem cell transplant <=3 months before the first dose of study treatment; b. Has evidence of graft versus host disease; c. Received donor lymphocyte infusion <=1 month before the first dose of study treatment; d. Requires immunosuppressant therapy (exception: daily doses <=10 milligrams (mg) prednisone or equivalent are allowed for adrenal replacement)