A Dose Escalation and Expansion Study Evaluating the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of RO7283420.

This open-label, entry-into-human (EIH) study will evaluate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics of RO7283420. Escalating doses of RO7283420 will be administered to participants with Acute Myeloid Leukemia (AML) in order to determine the maximum tolerated dose (MTD) and/or recommended Phase II dose (RP2D).

The study will include AML participants with measurable disease, for whom standard-of-care (SOC) is not available. Two Groups of AML participants will be included in this study: * Group I participants will have hematologic relapse/refractory disease defined as participants not in complete remission (CR) or complete remission with incomplete hematologic recovery (CRi). * Group II participants will have molecular relapse/persistent disease (participants with a CR or CRi, and a positive MRD based on local multi-parameter flow cytometry (MFC) or molecular assessment). The study consists of three parts: * Part A (single-participant dose escalation cohorts) - single participants from Group I will receive increment-based escalating doses until a Grade \>=2 AE related to RO7283420 or a clear pharmacodynamic effect * Part B (multiple-participant dose escalation cohorts) - multiple-participant cohorts of \>=3 participants will be enrolled for dose escalation for Group I and Group II independently. * Part C (dose expansion) - participants will receive the respective identified RP2D for that group. The treatment period for each participant will be up to 7 months with a maximum number of cycles depending on the dosing frequency the participant receives. Each participant will receive up to 6, 9, and 18 cycles of treatment with RO7283420, when treated with Q3W, every-2-weeks (Q2W), or once-a-week (QW) dosing regimens, respectively. Additional 3, 5, or 9 cycles may be administered for the Q3W, Q2W, and QW dosing regimens, respectively, in case the participants have achieved at least partial remission (PR).