Evaluation of Pembrolizumab in Lymphopenic Metastatic Breast Cancer Patients Treated With Metronomic Cyclophosphamide

One tablet per day. Cyclophosphamide will continue to be administered as long as patient experiences clinical benefit in the opinion of the investigator or symptomatic deterioration attributed to disease progression as determined by the investigator after an integrated assessment of radiographic data and clinical status or withdrawal of consent.

IV infusion every 3 weeks. Pembrolizumab will continue to be administered as long as patient experiences clinical benefit in the opinion of the investigator or symptomatic deterioration attributed to disease progression as determined by the investigator after an integrated assessment of radiographic data and clinical status or withdrawal of consent.