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

LIGHTBEAM-U01 Substudy 01E: A Phase 2 Substudy to Evaluate the Safety and Efficacy of Belzutifan in Participants With Solid Tumors

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.

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Has a diagnosis of one of the following: locally advanced, unresectable, or metastatic pheochromocytoma/paraganglioma or wild-type gastrointestinal stromal tumors, or localized tumors associated with von Hippel-Lindau disease
• Has measurable disease per RECIST 1.1

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Has a pulse oximeter reading <92% at rest, requires intermittent supplemental oxygen, or requires chronic supplemental oxygen
• Has clinically significant cardiac disease or electrocardiogram indicating uncontrolled cardiac condition or has congenital long QT syndrome
• Has a history of human immunodeficiency virus infection
• Has received prior treatment with any hypoxia inducible factor-2α inhibitor, including belzutifan
• Has had an allogenic tissue/solid organ transplant
• Has a history of autologous stem cell transplant within 6 months of start of study intervention
• Has known additional malignancy that is progressing or has required active treatment within the past 2 years
• Has known active central nervous system metastases and/or carcinomatous meningitis
• Has an active infection requiring systemic therapy