Immune Checkpoint Inhibitors in Breast Cancer: A Narrative Review

Breast cancer is the most frequently diagnosed malignancy in patients worldwide and the main cause of cancer-related death. Though still incurable, metastatic breast cancer’s prognosis has been considerably improved in the past 10 years due to the introduction of new targeted agents, such as immune checkpoint inhibitors (ICI). However, these medications are associated with unique side effects known as immune-mediated adverse events (irAE). In this paper, we review the clinical evidence for the use of ICIs in breast cancer, in both the metastatic as well as neoadjuvant/adjuvant setting, followed by a review of irAE most commonly seen, and the medications used to treat them. Our opinion is that any cancer specialist treating patients with breast cancer should be aware of these side effects for early detection and management, and oncologists should be the leaders of the multidisciplinary team that will take care of them.