Breast Cancer Study of Preoperative Pembrolizumab + Radiation

This study is being done to assess the feasibility of pembrolizumab (study drug) combined with standard radiation to the tumor (tumor boost) before patients undergo standard treatment that can consist of one or more of the following: breast-conserving surgery, radiation to the entire breast/chest wall after surgery, and chemotherapy. Study participants will receive two doses of the study drug intravenously (through the vein) before their planned breast surgery or chemotherapy. The study drug will be administered three weeks apart. At the time of the second dose, radiation to the tumor in the affected breast will be given. This type of radiation treatment is called a "tumor boost", which is a standard part of radiation therapy for breast cancer that may occur either before or after planned breast-conserving surgery. Patients will receive breast surgery or begin chemotherapy approximately six weeks after your first dose of the study drug.

NCT Number	NCT03366844
Lead Sponsor	Stephen Shiao Collaborators: United States Department of Defense
Conditions	Breast Cancer
Enrollment	66 participants
Start Date	2017-12-22
Primary Completion	2025-02-06 (estimated)
Study Completion	2030-12-07 (estimated)
Updated on ClinicalTrials.gov	2026-04-20