Additional Study Information: The study drug, CFT8634, is an investigational therapy that has been shown in animal studies to help break down the BRD9 protein, an important protein in the body that helps SMARCB-null tumors, such as your own, to grow. CFT8634 is able to do so by using the body's own protein-recycling equipment. (In short, your cells are capable of breaking down proteins into their amino acid building blocks in order to rebuild themselves again.) By breaking down the BRD9 protein, the study drug may be able to help destroy these cancer cells in humans. The purpose of this study is to find out if treatment with the study drug is safe, to find out the acceptable dose of the medication, and if it has any good or bad effects in people with SMARCB1-perturbed cancers. This is the first time the study drug is being tested in humans and it is not yet approved by the United States Food and Drug Administration (FDA).