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

What this study involves

The registry says this study is recruiting. Individual locations may have different availability.

Study type

Interventional

Phase

Phase 2

Age range

12 years - 17 years

Sex eligible

All sexes

Healthy volunteers

Not accepted

Participants

15 Estimated

These are starting points, not an eligibility decision. The research team must review the full requirements.

About the research

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.

Who may be able to participate?

The list below is the sponsor’s full registry wording. It can include conditions, prior treatment, test results and other requirements. A match in search does not mean you qualify.

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

Treatment, groups and participation

The registry may describe treatments and study duration without a complete visit calendar. Ask the study team for the exact schedule, procedures, risks, costs and alternatives. Keep your usual care plan unless your treating clinician tells you otherwise.

Assignment

Not applicable

Masking

No masking

What researchers are measuring

Outcome measures describe what is being studied. They are not proof that a treatment works.

Primary measures

Secondary measures

Research locations (10)

The overall study status and a local site’s status can differ. Confirm that location’s availability before traveling.

10 locations

Study team and timeline

Lead sponsor

Merck Sharp & Dohme LLC

Study start

Oct 13, 2026 Actual

Primary completion

Jan 2, 2034 Estimated

Study completion

Jan 2, 2034 Estimated

First posted

Jul 14, 2026 Actual

Last updated

Nov 10, 2026 Actual

Official study contacts