A Study to Compare the Blood Levels and Safety of Tazemetostat in Participants With Advanced Cancer and Moderate/Severe Liver Impairment to Participants With Advanced Cancer and Normal Liver Function

This study is comparing blood levels, safety, and effects of tazemetostat — an oral cancer drug that targets a specific protein involved in cancer cell growth — given at different doses or formulations to patients with advanced solid tumors or blood cancers that have stopped responding to prior treatments. **You may be eligible if...** - You are 18 or older - You have a confirmed advanced solid tumor that has progressed after standard treatments, with no remaining standard therapy options, OR a blood cancer that has relapsed after at least 2 standard treatments - You have measurable or evaluable disease on imaging - You are in reasonably good overall health (ECOG performance status 0-2) - Your expected survival is more than 3 months - Your prior treatment toxicities have largely resolved - You can swallow and retain oral medications **You may NOT be eligible if...** - You have had chemotherapy, targeted therapy, or major surgery within 28 days before study entry - You have significant organ dysfunction (blood counts, kidneys, liver) - You are pregnant or breastfeeding - You have serious uncontrolled gastrointestinal conditions that prevent absorbing oral medications - Your cancer has not failed at least the required number of prior treatments Talk to your doctor to see if this trial is right for you.