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

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• Age12 Years to 17 Years
• SexAll
• Healthy volunteersNo

You may be able to join if

• 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

You cannot join if

• 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

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

belzutifan. An orally active, small molecule inhibitor of hypoxia inducible factor (HIF)-2alpha (HIF-2a), with potential antineoplastic activity. Upon oral administration, belzutifan binds to and blocks the function of HIF-2alpha, thereby preventing HIF-2alpha heterodimerization and its subsequent binding to DNA. This results in decreased transcription and expression of HIF-2alpha downstream target genes, many of which regulate hypoxic signaling. This inhibits cell growth and survival of HIF-2alpha-expressing tumor cells. HIF-2alpha, the alpha subunit for the heterodimeric transcription factor HIF-2, is overexpressed in many cancers and promotes tumorigenesis. NCI Drug Dictionary

Treatments listed in the registry

• Belzutifan (Drug): Administered once daily via oral tablet

Na · Single Group · masking: None

Main goals

• Number of Participants Who Experience One or More Adverse Events (AEs) (Up to approximately 5 years)
• Number of Participants Who Discontinue Study Intervention Due to an AE (Up to approximately 5 years)

Other goals

• Area Under the Concentration-Time Curve From Time 0 to 24 hours of Belzutifan
• Minimum Plasma Concentration (Cmin) of Belzutifan
• Maximum Plasma Concentration (Cmax) of Belzutifan
• Objective Response Rate (ORR)
• Duration of Response (DOR)

Planned enrollment: 15 (estimated).

• University of Iowa ( Site 5017), Iowa City, Iowa

6 recruiting sites outside the US. Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT07700758
• NCI Drug Dictionary: C135627

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Oct 22, 2026. Public record; not medical advice.