Pembrolizumab and Oral Metronomic Cyclophosphamide in Patients With Chest Wall Breast Cancer

This is a Phase II single center, open-label, non-randomized study in patients with locally recurrent, inoperable, and/or metastatic inflammatory breast cancer with lymphangitic spread to the chest wall. Patients will be treated with pembrolizumab administered as an intravenous infusion at 200 mg in 21-day treatment cycles and oral cyclophosphamide (CTX) 50 mg per day in metronomic administration as a 21 days cycle Forty-six patients will be required for the study. Key inclusion criteria are PDL1 (≥1%) positive and/or tumor infiltrating lymphocyte positive (≥1%) locally advanced "chest wall" breast cancer (with or without distant metastases), who have been treated with chemotherapy or radiation therapy may be eligible for this study. Patients with cutaneous metastases only (with or without evidence of primary tumor) are eligible for the study. Key exclusion criteria included prior anti PD1 or anti CTLA-4 or other immune pathway-targeted therapy. Patients with autoimmune diseases and/or receiving drugs who interfere with the immune system will not be eligible.