A Study of Belzutifan in Adolescent Participants With Solid Tumors (MK-9999-01E/LIGHTBEAM-U01)

Researchers are looking for new ways to treat adolescents with locally advanced, unresectable, or metastatic solid tumors. Participants were enrolled into pheochromocytoma/paraganglioma (PPGL), wild type gastrointestinal stromal tumor (wtGIST), and Von Hippel-Lindau (VHL) disease-associated localized tumors cohorts: * PPGL are rare cancers that start in cells that make hormones in the adrenal glands * wtGIST is a less common type of cancer that starts in the digestive tract. Wild type means it does not have certain gene mutations (changes) * VHL disease-associated localized tumors are rare tumors caused by a certain gene mutation that may be passed down from parents to children * Locally advanced means the cancer has spread into nearby tissue * Unresectable means the cancer cannot be removed by surgery * Metastatic means the cancer has spread to other parts of the body The goal of the study is to learn about the safety of belzutifan and if people tolerate it.