Table 1.

Current International guidelines regarding the use of PARP-inhibitors in BC patients with metastatic disease.

Society	Recommendation
ASCO[18]	Patients with TN metastatic BC with germline BRCA1 or 2 mutations who have previously been treated with chemotherapy in the neoadjuvant, adjuvant, or metastatic disease setting may be offered an oral PARP inhibitor rather than chemotherapy (Type: evidence-based; benefits outweigh harms; Evidence quality: moderate; Strength of recommendation: strong). Patients with HR-positive/HER2-negative metastatic BC with germline BRCA1 or 2 mutations who are no longer benefiting from ET may be offered an oral PARP inhibitor in the first-through to third-line setting rather than chemotherapy (Type: evidence-based; benefits outweigh harms; Evidence quality: moderate; Strength of recommendation: strong)
NCCN[19]	The NCCN Panel recommends assessing for germline BRCA 1/2 mutations in all patients with recurrent or metastatic BC to identify candidates for PARP-inhibitor therapy. While olaparib and talazoparib are FDA indicated in HER2-negative disease, the NCCN Panel supports use in any BC subtype associated with germline BRCA 1/2 mutations.
ESMO[17]	Patients with HER2-negative metastatic BC and germline pathogenic or likely pathogenic variants in BRCA1 or BRCA2 should be offered treatment with a PARP inhibitor (olaparib or talazoparib), independent of HR status, as an alternative to chemotherapy [I, A; ESMO-MCBS v1.1 score: 4; ESCAT score: I-A]. Prior treatment with anthracyclines and taxanes should not be required before offering patients with metastatic BC and BRCA germline mutation treatment with a PARP inhibitor; nor should HR-positive patients be required to demonstrate complete endocrine resistance [I, D].
ESO-ESMO [20]	For patients with a germline BRCA mutation, single agent PARP inhibitor (olaparib or talazoparib) is a preferred treatment option for those with triple-negative advanced BC. In ER-positive germline BRCA-associated advanced BC, the optimal sequence between a PARP inhibitor and ET with or without a CDK4/6 inhibitor is unknown. Given the OS benefit seen with CDK4/6 inhibitors, the panel recommends their use before a PARP inhibitor.

Abbreviations: ASCO, American Society of Clinical Oncology; NCCN, National Comprehensive Cancer Network; ESMO, European Society of Medical Oncology; TN, triple-negative; BC, breast cancer; ET, endocrine therapy; MCBC, magnitude clinical benefit scale; ESCAT, ESMO Scale for Clinical Actionability of molecular Targets.