The main objective of the dose-escalation part of the trial is to determine the safety and tolerability, Pharmacokinetic (PK), biomarkers, and efficacy, and to determine the Maximum Tolerated Dose and/or the Recommended Phase 2 Dose (RP2D) of BI 754091 on the basis of patients with dose-limiting toxicities (DLTs) in patients with selected advanced solid malignancies. Safety and tolerability will be evaluated by monitoring the occurrence of adverse events (AEs), serious AEs (SAE), and laboratory parameter abnormalities, as well as changes to vital signs.