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

Exclusion Criteria

• •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