A case of metastatic triple negative breast cancer patient with BRCA2 pathogenic variant who administered PARP inhibitor prior to immune-checkpoint inhibitor and chemotherapy

With the introduction of new agents such as poly (adenosine diphosphate ribose) polymerase (PARP) inhibitors, immune-checkpoint inhibitors (ICIs), and trastuzumab deruxtecan, the range of effective treatment options for patients with metastatic triple negative breast cancer (mTNBC) has considerably expanded. Generally, mTNBC is recognized as an aggressive disease with a poor prognosis, making the improvement of patient outcomes a critical issue. However, for patients harboring BRCA1/2 pathogenic variants and programmed death ligand 1 (PD-L1) positivity or having human epidermal growth factor receptor 2-low disease, the recommended treatment protocols for these agents remain unclear. In this report, we discuss the case of a patient with a BRCA2 pathogenic variant and PD-L1 positive mTNBC who received PARP inhibitors as a first-line therapy, followed by ICIs and chemotherapy as second-line regimen.