Effects of Itraconazole and Rifampin on the Blood Tazemetostat Levels

The participants of this study will have advanced malignancies (also known as advanced cancer). The main aim of this trial will be to study the blood levels (known as pharmacokinetics) of the tazemtostat (the study drug) when administered in combination with another drug. Part 1 of the study will evaluate the interaction between the drugs tazemetostat and itraconazole. Part 2 of the study will evaluate the interaction between the drugs tazemetostat and rifampin For both Parts 1 and 2, safety and the level that effects of the study drug can be tolerated (known as tolerability) will be assessed throughout.