Developing therapies for triple-negative breast cancer subtypes

Metastatic triple-negative breast cancer is associated with a poor prognosis due to its aggressive tumour biology and the small number of effective treatments; the latter is historically due to the absence of either oestrogen or HER2 receptor expression against which to direct therapies. Recent years have seen the development of new treatments, with PD1/PD-L1 immune checkpoint inhibitors, antibody–drug conjugates that deliver chemotherapy more selectively, and poly (ADP-ribose) polymerase inhibitors for patients with BRCA1/BRCA2 germline mutations.