TROFUSE-010

An Open-label, Randomized Phase 3 Study of MK-2870 as a Single Agent and in Combination with Pembrolizumab Versus Treatment of Physician’s Choice in Participants with HR+/HER2- Unresectable Locally Advanced or Metastatic Breast Cancer

• Has unresectable locally advanced or metastatic centrally-confirmed hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer

• Has radiographic disease progression on one or more lines of endocrine therapy for unresectable locally advanced/metastatic HR+/HER2- breast cancer, with one in combination with a CDK4/6 inhibitor

• Is a chemotherapy candidate

• Has an eastern cooperative oncology group (ECOG) performance status of 0 to 1 assessed within 7 days before randomization

• Has adequate organ function

• Human immunodeficiency virus (HIV)-infected participants must have well controlled HIV on antiretroviral therapy

• Participants who are Hepatitis B surface antigen (HBsAg) positive are eligible if they have received HBV antiviral therapy for at least 4 weeks, and have undetectable HBV viral load

• Participants with a history of Hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable