Dendritic Cell Vaccines Against Her2/Her3 and Pembrolizumab for the Treatment of Brain Metastasis From Triple Negative Breast Cancer or HER2+ Breast Cancer

This phase IIa trial studies how well dendritic cell vaccines against Her2/Her3 and pembrolizumab work for the treatment of triple negative breast cancer or HER2+ breast cancer or HER+ Breast cancer that has spread to the brain (brain metastasis). Dendritic cell vaccines work by boosting the immune system (a system in the body that protect against infection) to recognize and destroy the cancer cells. . Pembrolizumab is an "immune checkpoint inhibitor" which is designed to either "unleash" or "enhance" the cancer immune responses that already exist by either blocking inhibitory molecules" or by activating stimulatory molecules. Giving dendritic cell vaccines and pembrolizumab may shrink the cancer.