Outcome of patients with metastatic triple negative breast cancer treated with first-line chemotherapy: a single institution retrospective analysis.

No differences in clinical outcome were found according to PD-L1 status or chemotherapy regimen chosen. In "unselected" patients, single agent or combination chemotherapy could be appropriate, although in the immunotherapy era patients with newly diagnosed mTNBC should be routinely tested for PD-L1 status. The variability in PD-L1 expression by metastatic site warrants further investigation.