Additional Study Information: The purpose of this study is to identify the most appropriate dose that can be safely administered and that can have an effect on haematological cancer cells. BAY 1251152 works by obstructing a protein in your bodys cells called positive transcription elongation factor b (PTEFb) / cyclin-dependent kinase 9 (CDK9) pathway, which plays a role in the growth of tumor cells in humans. It is believed that the experimental drug may slow down and/or stop the growth of tumors. The study will also investigate the pharmacokinetics (study of what the body does to the drug), as well as pharmacodynamics (study of what the drug does to the body), which may provide information about the effects of BAY 1251152. The study will also measure some biological markers (markers of biological activity in your body) that can be used to predict the response and safety of the proposed treatment.