Abstract OT1-02-02: A phase II study of pembrolizumab in combination with palliative radiotherapy for metastatic hormone receptor positive breast cancer

BACKGROUND: Despite recent advances in the treatment of patients with metastatic hormone receptor positive (HR+)/HER2- breast cancer (BC), it remains an incurable disease. The activity of immune checkpoint inhibitors (ICI) as monotherapy in patients with metastatic HR+/HER2- BC has been limited. Therefore, the addition of other strategies that elicit an immunogenic tumor microenvironment may be needed. We hypothesize that radiation therapy (RT)...