The purpose of the first phase of this study (phase I) is to find the dose of a new therapy, CX5461, that can be tolerated without causing very severe side effects and to see what effects the study drug has this cancer. Participants are given CX5461 and are watched very closely to see what side effects they have and to make sure the side effects are not severe. If serious side effects are seen in patients at the first dose level, doses of CX5461 may be lowered in subsequent patients. If the side effects are not serious, then more participants are asked to join this study and are given higher doses. This will continue until a dose is found that causes severe but temporary side effects. Doses higher than that will not be given.