MK2870-010

The purpose of this study is to test the safety and anti-cancer activity of the drug MK-2870 (sacituzumab tirumotecan, also called sac-TMT) given alone and MK-2870 given with pembrolizumab (MK-2870 plus pembro) in people with advanced breast cancer that cannot be surgically removed. In addition, the study will test the safety of the study drugs, evaluate how well the drugs work compared to each other, determine which treatments help participants live longer, and assess which treatments improve participants’ quality of life.

This study will compare MK-2870 given alone and MK-2870 combined with pembrolizumab to four standard chemotherapies commonly used to treat breast cancer: paclitaxel, nab-paclitaxel, capecitabine, and liposomal doxorubicin. It will also compare MK-2870 given alone to MK-2870 combined with pembrolizumab.

MK-2870 is investigational. “Investigational” means that it is not yet approved by the U.S. Food and Drug Administration (FDA) and it must be tested to see if it is a safe and effective treatment for the disease or condition being studied. It has not been approved to use alone or in combination with pembrolizumab.

Pembrolizumab (pembro) is also called KEYTRUDA™. Pembrolizumab has been approved by certain health authorities for treating various cancers, including some types of breast cancer. Pembrolizumab is not approved for hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer.

In order to participate you must meet the following criteria:

• Have unresectable locally advanced or metastatic centrally-confirmed hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer.
• Have 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.
• Are a chemotherapy candidate.
• Have an eastern cooperative oncology group (ECOG) performance status of 0 to 1.
• Have adequate organ function.

You will be excluded from the study if any of the following criteria apply to you:

• Have breast cancer amenable to treatment with curative intent.
• Have experienced an early recurrence (<6 months after completing adjuvant/neoadjuvant chemotherapy) and therefore is eligible to receive second-line (2L) treatment.
• Have symptomatic advanced/metastatic visceral spread at risk of rapidly evolving into life-threatening complications.
• Have received prior chemotherapy for unresectable locally advanced or metastatic breast cancer.

This is a partial list of eligibility requirements. To inquire about your eligibility, please call the contact number provided. If you wish to inquire via email, please include the title of the study in your message.