You are being asked to take part in this research study because your tumor results from the NCI-COG Pediatric MATCH screening protocol make you a candidate to receive the study drug called BVD-523FB (ulixertinib) that we are testing in this study. The overall goal of this study is to test any good and bad effects of the study drug BVD-523FB (ulixertinib) on your tumor. A second goal of the study is to evaluate side effects that might be caused by BVD-523FB (ulixertinib), which could shrink your cancer but it could also cause side effects and to learn more about the pharmacology (how your body handles the drug) of BVD-523FB (ulixertinib).