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

NCT07700758 | Not Yet Recruiting Phase 2 FDA Drug

• 5 other identifiers: 9999-01EU1111-1330-93702025-524515-37-00MK-9999-01ELIGHTBEAM-U01
• Study Type: interventional
• Target: 15
• Locations: 0 countries
• Sites: N/A

Brief Summary

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.

Conditions

Malignant Neoplasm

Outcome Measures

Primary Outcomes (2)

• Number of Participants Who Experience One or More Adverse Events (AEs)

  An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants that experience AEs will be reported.

  Up to approximately 5 years

• Number of Participants Who Discontinue Study Intervention Due to an AE

  An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The number of participants that discontinue study intervention due to an AE will be reported.

  Up to approximately 5 years

Secondary Outcomes (5)

• Area Under the Concentration-Time Curve From Time 0 to 24 hours of Belzutifan

  At designated timepoints (up to 5 weeks)

• Minimum Plasma Concentration (Cmin) of Belzutifan

  At designated timepoints (up to 5 weeks)

• Maximum Plasma Concentration (Cmax) of Belzutifan

  At designated timepoints (up to 5 weeks)

• Objective Response Rate (ORR)

  Up to approximately 5 years

• Duration of Response (DOR)

  Up to approximately 5 years

Study Arms (1)

Belzutifan

EXPERIMENTAL

Participants will receive belzutifan 80 mg (body weight \<40 kg) or 120 mg (body weight ≥40 kg) orally once daily for approximately 2 years.

Drug: Belzutifan

Interventions

Belzutifan DRUG

Administered once daily via oral tablet

Also known as: MK-6482, PT2977, WELIREG®

Belzutifan

Eligibility Criteria

• Age: 12 Years - 17 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• 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 may not qualify if:

• 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

Sponsors & Collaborators

• Merck Sharp & Dohme LLC: lead

Related Links

• Merck Clinical Trials Information

MeSH Terms

Conditions

Neoplasms

Interventions

belzutifan

Study Officials

• Medical Director

  Merck Sharp & Dohme LLC

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 8, 2026
• First Posted: July 14, 2026
• Study Start (Estimated): November 23, 2026
• Primary Completion (Estimated): January 2, 2034
• Study Completion (Estimated): January 2, 2034
• Last Updated: July 14, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share