The main purpose of this study is to learn how well tumors that have specific genetic changes (mutations) respond to drugs that target those changes. This combination of a tumor with a mutation and a drug that aims at that mutation is called a match. There are two steps for participants in this study: The first step is called screening. The purpose of screening is to perform tests on your tumor tissue to find out what mutations, if any are present in your tumor. To be eligible for screening, you must have a tumor sample already available for testing, or there must be a way to do a biopsy of your tumor that your doctor thinks is safe. The consent form you are reading now is for the screening step of the Pediatric MATCH study. The second step is the investigational treatment part of the study. In this step we will see whether there is an investigational (experimental) drug available through the Pediatric MATCH study that targets the mutations (if any) that are found in your tumor. If so, your study doctor will tell you about the drug and explain the specifics of getting that drug. He or she will explain the potential side effects and benefits of the drug. In some cases, the side effects of these drugs in children might not be known. If you consent and are eligible, you will then receive the drug and we will look to see what its effects are on your tumor.