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Study of Belzutifan Plus Fulvestrant for ER+/HER2- Metastatic Breast Cancer

This study is looking at how well belzutifan plus fulvestrant works and if it's safe for adults with a type of breast cancer called estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer. This is a type of breast cancer that has spread and cannot be removed by surgery. Researchers are comparing this combination to everolimus plus either fulvestrant or exemestane. You may be able to join if you are 18 or older, have this specific type of breast cancer, and your cancer has gotten worse after previous endocrine therapy. The main goal is to see how long people live without their cancer growing or spreading (progression-free survival), which will be measured for up to about 29 months. The current recruitment status is unclear.

Study design
This interventional study plans to enroll 120 participants. It compares two different treatment combinations for metastatic breast cancer.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
The study will measure how long participants live without their cancer growing or spreading for up to approximately 29 months.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT06428396

Study of Belzutifan (MK-6482) Plus Fulvestrant for ER+/HER2- Metastatic Breast Cancer (MK-6482-029/LITESPARK-029)

Active, Not Recruiting
PHASE2Ages 18+InterventionalTreatment
Merck Sharp & Dohme LLC
~120 participants
Updated 2026-08-28 on ClinicalTrials.gov
What's tested:BelzutifanFulvestrantEverolimusExemestane

At a glance

Recruiting sites
0 of 41 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Progression-free Survival (PFS)
Measured over Up to approximately 29 months

Conditions

Metastatic Breast Cancer

Explore related trials

Breast Carcinoma

Where it's being run

41 sites across 28 states
California4
Buenos Aires3
Region M. de Santiago3
Taiwan3
Georgia2
Texas2
Wisconsin2
South Korea2

Study leadership

  • Medical Director · STUDY_DIRECTOR · Merck Sharp & Dohme LLC

Who to contact

This trial hasn't published a contact. View it on ClinicalTrials.gov

Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Has a diagnosis of estrogen receptor positive (ER+)/human epidermal growth factor receptor negative (HER2-) invasive breast carcinoma that is either locally advanced disease not amenable to resection or metastatic disease not treatable with curative intent
Has documented radiographic confirmation of disease progression during or after the last administered endocrine therapy (ET)
Provides additional tissue from the same sample used to determine ER and HER2 status locally
Has received ET in the noncurative setting and has 1) Radiographic disease progression on 12 months or more of ET in combination with CDK4/6 inhibitor in the noncurative setting or 2) Received at least 2 lines of ET in the noncurative setting including CDK4/6 inhibitor where the CDK 4/6 inhibitor was discontinued due to intolerance
Has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 assessed within 7 days of randomization
Participants who have AEs due to previous anticancer therapies must have recovered to ≤Grade 1 or baseline. Participants with endocrine-related AEs who are adequately treated with hormone replacement or participants who have ≤Grade 2 neuropathy are eligible
Participants who are hepatitis B surface antigen (HBsAg) positive are eligible if they have received hepatitis B virus (HBV) antiviral therapy for at least 4 weeks prior to the first dose of study intervention and have undetectable HBV viral load prior to randomization

Exclusion

Has Breast cancer amenable to treatment with curative intent
Is unable to receive any of the endocrine therapies (ETs) (ie, fulvestrant or exemestane)
Has known difficulty in tolerating oral medications, unable to swallow orally administered medication, or conditions which would impair absorption of oral medications such as uncontrolled nausea or vomiting (ie, CTCAE =Grade 3 despite antiemetic therapy), ongoing gastrointestinal obstruction, motility disorder, malabsorption syndrome, or prior gastric bypass
Has advanced/metastatic, symptomatic visceral spread at risk of rapidly evolving into life-threatening complications
Has active, bleeding diathesis, or on oral anti-vitamin K medication
Has history of noninfectious pneumonitis/interstitial lung disease including radiation pneumonitis that required steroids or has current pneumonitis/interstitial lung disease
Has a known germline BRCA mutation (deleterious or suspected deleterious) and has received previous treatment with poly-ADP ribose polymerase (PARP) inhibition either in the adjuvant or metastatic setting
Has received prior fulvestrant in the adjuvant, unresectable locally advanced, or metastatic setting
Has received any line of cytotoxic chemotherapy or PARP inhibitor in the unresectable or noncurative advanced/metastatic setting
Has received prior radiotherapy for non-central nervous system (CNS) disease or required corticosteroids for radiation-related toxicities including radiation pneumonitis, within 14 days of the first dose of study intervention
Is currently receiving either a strong inhibitor or inducer of CYP3A4 that cannot be discontinued for the duration of the study
Has received prior systemic anticancer therapy including investigational agents within 4 weeks before randomization
Has received a live or live-attenuated vaccine within 30 days before the first dose of study intervention
Has concurrent active Hepatitis B and Hepatitis C virus infection
Has clinically significant cardiac disease, including unstable angina, acute myocardial infarction within 6 months from Day 1 of study medication administration, or New York Heart Association Class III or Class IV congestive heart failure
Has not adequately recovered from major surgery or have ongoing surgical complications

What this trial measures

  • Progression-free Survival (PFS)Up to approximately 29 months

    PFS is defined as the time from randomization to the first documented disease progression per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) based on blinded independent central review (BICR) or death due to any cause, whichever occurs first.