Overview

The purpose of Part 1 (Dose Escalation) of the study is to assess the effective dose (recommended Phase 2 dose\[s\] \[RP2Ds\]) that can be safely administered, and dosing regimens of JNJ-90189892 in participants with relapsed or refractory (R/R) acute myeloid leukemia (AML) or R/R higher-risk type of myelodysplastic neoplasms (MDS \[type of cancer of the blood and bone marrow, which does not respond to treatment or comes back after treatment\]). The purpose of Part 2 (Cohort Expansion) is to further assess the safety, tolerability and efficacy in participants with R/R AML or higher-risk types of MDS at the RP2D regimen(s). The purpose of Part 3 and 4 is to assess the effective dose (recommended Phase 2 combination dose \[RP2CD\]) that can be safely administered, and dosing regimens of JNJ-90189892 in combination with azacitadine (AZA) + venetoclax (VEN) in participants with R/R AML (part 3) and newly diagnosed (ND) AML (part 4).

Eligibility

Inclusion Criteria:

• A. For Parts 1, 2, and 3: Have a diagnosis, per the world health organization (WHO) 2022 criteria, of (a) Parts 1, 2, and 3: Acute myeloid leukemia (AML) or (b) Parts 1 and 2: Moderate high, high, or very high-risk myelodysplastic neoplasms (MDS) per Molecular International Prognostic Scoring System (IPSS-M); B. For Part 4 only: Previously untreated acute myeloid leukemia (AML) per the WHO 2022 criteria
• Body weight that is greater than or equals to (\>=) 40 kg
• Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2
• Have adequate renal function defined as Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) Estimated Glomerular Filtration Rate (eGFR) \>=40 milligrams per minute (mL/min) computed with the calculator on the national kidney foundation website
• Participants must have laboratory parameters in the required range

Exclusion Criteria:

• Has a medical history of clinically significant pulmonary compromise, particularly the current need for supplemental oxygen use to maintain adequate oxygenation
• Has evidence of uncontrolled systemic viral, bacterial, or fungal infection. Antimicrobial prophylaxis is permitted
• All participants- Has known allergies, hypersensitivity, or intolerance to JNJ-90189892 or its excipients; Parts 3 and 4- Has known allergies, hypersensitivity, or intolerance to venetoclax (VEN), azacitadine (AZA), or their excipients
• Had major surgery or had significant traumatic injury within 14 days of planned first dose of JNJ-90189892
• Had a prior or concurrent second malignancy with natural history or treatment likely to interfere with any study endpoints of safety or the efficacy of the study treatment
• Has known active central nervous system involvement