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Metastatic Breast CancerPhase 2NCT06428396

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

A Phase 2 study testing Belzutifan, Fulvestrant and Everolimus in people with Metastatic Breast Cancer, run by Merck Sharp & Dohme LLC at 41 sites in 9 countries.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

The purpose of this study is to assess the efficacy and safety of belzutifan (MK-6482) plus fulvestrant compared to everolimus plus endocrine therapy (ET) (investigator's choice of fulvestrant or exemestane) in adults with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2-)… Read more about this study

Who is it for?
Ages 18 years and older
Conditions the study is for
Metastatic Breast Cancer
What is being tested?
Belzutifan, Fulvestrant and Everolimus
Could I receive a placebo?
No, everyone receives an active treatment
How many people
120 participants
Where
41 sitesin 9 countries
Study dates
27 Nov 2024to 25 Dec 2028
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • 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

Who cannot join

  • 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
Show all 16Show fewer
  • 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

Trial locations and contacts

41 sites in 9 countries.

41 sites in 9 countries

United States14 sites

  • Cedars Sinai Medical Center ( Site 0012)

    Beverly Hills, California, 90211

  • MD Anderson Cancer Center at Cooper ( Site 0024)

    Camden, New Jersey, 08103

  • City of Hope - Phoenix ( Site 0006)

    Goodyear, Arizona, 85338

  • MD Anderson ( Site 0015)

    Houston, Texas, 77030

  • Moores Cancer Center at UC San Diego Health ( Site 0025)

    La Jolla, California, 92093

  • USC/Norris Comprehensive Cancer Center ( Site 0013)

    Los Angeles, California, 90033

  • SSM Health Dean Medical Group - South Madison Campus Health Research/Circuit Clinical ( Site 0034)

    Madison, Wisconsin, 53715

  • Northwest Georgia Oncology Centers, a Service of Wellstar Cobb Hospital ( Site 0011)

    Marietta, Georgia, 30060

  • Medical College of Wisconsin - Froedtert Hospital ( Site 0014)

    Milwaukee, Wisconsin, 53226

  • Southeastern Regional Medical Center ( Site 0010)

    Newnan, Georgia, 30265

  • USC Norris Oncology Hematology Newport Beach ( Site 0029)

    Newport Beach, California, 92663

  • Renown Regional Medical Center ( Site 0018)

    Reno, Nevada, 89502

  • Mays Cancer Center ( Site 0022)

    San Antonio, Texas, 78229

  • CHRISTUS Highland ( Site 0005)

    Shreveport, Louisiana, 71105

Other trials in United States

Argentina7 sites

  • Instituto Alexander Fleming-Alexander Fleming ( Site 0505)

    Buenos Aires, Buenos Aires F.D., C1426ANZ

  • Centro de Investigaciones Metabólicas (CINME)-Oncology ( Site 0504)

    CABA, Buenos Aires, C1056ABI

  • Hospital Británico de Buenos Aires-Oncology ( Site 0500)

    Ciudad Autónoma de Buenos Aires, Buenos Aires, C1280AEB

  • Sanatorio Allende - Cerro-Oncology ( Site 0506)

    Córdoba, Córdoba Province, 5000

  • Hospital Italiano de Córdoba ( Site 0508)

    Córdoba, X5004BAL

  • Instituto de Investigaciones Clínicas Mar del Plata ( Site 0502)

    Mar del Plata, Buenos Aires, B7600FZO

  • Instituto de Oncología de Rosario ( Site 0501)

    Rosario, Santa Fe Province, S2000KZE

Other trials in Argentina

Chile4 sites

  • FALP ( Site 4102)

    Santiago, Region M. de Santiago, 7500921

  • Pontificia Universidad Catolica de Chile ( Site 4108)

    Santiago, Region M. de Santiago, 8330024

  • Bradfordhill ( Site 4100)

    Santiago, Region M. de Santiago, 8420383

  • Centro de Investigación del Maule ( Site 4106)

    Talca, Maule Region, 3460000

Other trials in Chile

United Kingdom4 sites

  • Ipswich Hospital ( Site 1911)

    Ipswich, Suffolk, IP4 5PD

  • St Bartholomews Hospital ( Site 1900)

    London, London, City of, EC1A 7BE

  • The Royal Cornwall Hospital ( Site 1904)

    Truro, England, TR1 3LJ

  • The Christie Hospital NHS Foundation Trust ( Site 1902)

    Withington, Manchester, M20 4BX

Other trials in United Kingdom

Colombia3 sites

  • Fundacion Valle del Lili ( Site 1204)

    Cali, Valle del Cauca Department, 760032

  • IMAT S.A.S ( Site 1205)

    Montería, Departamento de Córdoba, 230002

  • Oncologos Del Occidente ( Site 1200)

    Pereira, Risaralda Department, 660001

Other trials in Colombia

Taiwan3 sites

  • National Cheng Kung University Hospital ( Site 3300)

    Tainan, 704302

  • National Taiwan University Hospital ( Site 3301)

    Taipei, 10002

  • National Taiwan University Cancer Center ( Site 3302)

    Taipei, 106

Other trials in Taiwan

Thailand3 sites

  • Faculty of Medicine Siriraj Hospital ( Site 3500)

    Bangkoknoi, Bangkok, 10700

  • Songklanagarind Hospital ( Site 3501)

    Hat Yai, Changwat Songkhla, 90110

  • Faculty of Medicine - Khon Kaen University ( Site 3502)

    Muang, Changwat Khon Kaen, 40002

Other trials in Thailand

South Korea2 sites

  • Seoul National University Hospital ( Site 3100)

    Seoul, 03080

  • Samsung Medical Center ( Site 3101)

    Seoul, 06351

Other trials in South Korea

Canada1 site

  • Jewish General Hospital ( Site 0400)

    Montreal, Quebec, H3T 1E2

Other trials in Canada

About this study

Official title: A Phase 2, Randomized, Active-controlled, Open-label, Multicenter Study of Belzutifan Plus Fulvestrant in Participants With Estrogen Receptor Positive, HER2 Negative Unresectable Locally Advanced or Metastic Breast Cancer After Progression on Previous Endocrine Therapy (LITESPARK-029)

The purpose of this study is to assess the efficacy and safety of belzutifan (MK-6482) plus fulvestrant compared to everolimus plus endocrine therapy (ET) (investigator's choice of fulvestrant or exemestane) in adults with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2-) unresectable metastatic breast cancer. There is no formal hypothesis testing in this study.

Being tested
Belzutifan, Fulvestrant, Everolimus, Exemestane
Medical subject headings
Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • BelzutifanDrug

    Also called MK-6482

    Belzutifan 120 mg administered QD as an oral tablet.

  • FulvestrantDrug

    Fulvestrant 500 mg administered as an IM injection.

  • EverolimusDrug

    Administered at 10mg via oral tablets QD.

  • ExemestaneDrug

    Administered at 25 mg via oral tablets QD.

Study groups in NCT06428396
Study groupRoleWhat they receive
Belzutifan + FulvestrantExperimentalParticipants will receive belzutifan 120 mg orally once daily (QD) PLUS fulvestrant 500 mg via intramuscular (IM) injection on Days 1 and 15 of Cycle 1, and Day 1 of each 28-day cycle thereafter until progressive disease or discontinuation.
Receives: Drug: Belzutifan; Drug: Fulvestrant
Everolimus + ET (fulvestrant or exemestane)Active comparatorParticipants will receive everolimus 10 mg orally QD PLUS investigator's choice of fulvestrant 500 mg via IM injection on Days 1 and 15 of Cycle 1, and Day 1 of each 28-day cycle thereafter OR exemestane 25 mg orally QD until progressive disease or discontinuation.
Receives: Drug: Fulvestrant; Drug: Everolimus; Drug: Exemestane

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Progression-free Survival (PFS)

    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.

    Measured: Up to approximately 29 months

Secondary outcomes (7)

  1. Progression-free Survival (PFS) at 6 months

    PFS data will be cumulated to a certain cut-off date and the analysis will be performed via Kaplan-Meier approach to estimate the PFS rate at 6 months using the entire PFS data up to the cut-off date. The cut-off date is event-driven and estimated to be approximately 28 months.

    Measured: Up to approximately 29 months

  2. Progression-free Survival (PFS) at 12 months

    PFS data will be cumulated to a certain cut-off date and the analysis will be performed via Kaplan-Meier approach to estimate the PFS rate at 12 months using the entire PFS data up to the cut-off date. The cut-off date is event-driven and estimated to be approximately 28 months.

    Measured: Up to approximately 29 months

  3. Overall Survival (OS)

    OS is defined as the time from randomization to death due to any cause.

    Measured: Up to approximately 29 months

  4. Objective Response Rate (ORR)

    ORR is defined as the percentage of participants who have achieved confirmed Complete Response (CR: disappearance of all target lesions) or a Partial Response (PR: at least a 30% decrease in the sum of diameters of target lesions) per RECIST 1.1 as assessed by BICR.

    Measured: Up to approximately 29 months

  5. Clinical Benefit Rate (CBR)

    CBR is defined as the percentage of participants who have CR: Disappearance of all target lesions, PR: At least a 30% decrease in the sum of diameters of target lesions, or stable disease (SD: Neither sufficient decrease to qualify for PR nor sufficient increase to qualify for PD, taking as reference the smallest sum diameters while on study) for ≥24 weeks per RECIST 1.1 as assessed by BICR.

    Measured: Up to approximately 29 months

  6. Number of Participants Who Experience an Adverse Event (AE)

    An AE was 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 could therefore have been 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.

    Measured: Up to approximately 46 months

  7. Number of Participants Who Discontinue Study Treatment Due To an AE

    An AE was 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 could therefore have been 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.

    Measured: Up to approximately 46 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted24 May 2024
  2. Study start27 Nov 2024
  3. Primary completion5 May 2027 (estimated)
  4. Study completion25 Dec 2028 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
120 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06428396
Sponsor's protocol ID
6482-029
Other IDs
MK-6482-029, LITESPARK-029
Status last verified
Aug 2026
First submitted
20 May 2024
Last updated
28 Aug 2026
Results posted
No
Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing Belzutifan, Fulvestrant and Everolimus in people with Metastatic Breast Cancer, run by Merck Sharp & Dohme LLC at 41 sites in 9 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 16 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 28 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 41 sites in United States, Argentina, Chile, United Kingdom, Colombia and 4 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Progression-free Survival (PFS) (time frame: Up to approximately 29 months). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06428396.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Aug 2026.

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