BTM-3566 in Advanced Solid Tumors

The goal of this clinical trial is to learn about what doses of BTM-356 are safe to use in adults with advanced cancers in solid tumors. It will also learn about how effective different doses of BTM-3566 are in treating cancer. The main questions it aims to answer are: What adverse events and toxicities (harmful side effects) are associated with different doses of BTM-3566? What are the blood levels of BTM-3566 in your body at different timepoints? What effect does BTM-3566 have on reducing tumor size and/or preventing the worsening of cancer? All participants will receive BTM-3566 and none will receive placebo (a look-alike substance that contains no drug). Participants will: * Take BTM-3566 for 7 days, then take a 7 day break. This 2 week dosing schedule of 7 days on/7 days off will continue until your disease worsens or you cannot tolerate treatment. * Visit the clinic approximately 7 times during screening and the first month of treatment. Visits will be reduced to approximately 2 visits per month after. * Keep a diary of when (and how much) BTM-3566 you take, along with how much you weigh on each dosing day.