Current usage of pembrolizumab in triple negative breast cancer (TNBC)

IntroductionThe use of immune checkpoint inhibitors (ICI) targeting the PD-1/PD-L1 pathway has changed the landscape in the treatment of triple negative breast cancer (TNBC). The ICI pembrolizumab in combination with chemotherapy now forms a standard of care for the treatment of advanced PD-L1 positive TNBC and as part of neoadjuvant therapy for high-risk early-stage disease. Evidence in this space is rapidly advancing.Areas coveredThis review aims to highlight the evolving role of immunotherapy in TNBC management and to discuss current challenges. The studies in this review were searched from PubMed and ClinicalTrials.gov.Expert opinionThe KEYNOTE-522 trial demonstrated that the addition of peri-operative pembrolizumab to neoadjuvant chemotherapy improves patient outcomes in early-stage TNBC. However, critical questions remain including how to select which patients truly gain benefit from the addition of pembrolizumab; the optimal duration of therapy, and the optimal adjuvant therapy depending on pathologic response.