BRCA-mutated metastatic breast cancer is a type of metastasized breast cancer whose tumors have a germline BRCA-mutation. Olaparib, a poly (ADP-ribose) polymerase inhibitor, when combined with standard immunotherapy like durvalumab, has shown significant antitumor activity. This study aims to examine the safety of olaparib-durvalumab combination therapy for the treatment of BRCA-mutated metastatic breast cancer.

This multicenter, open-label, phase1/2, basket trial included a total of 34 patients with BRCA-mutated metastatic breast cancer (germline BRCA1-mutated or BRCA2-mutated or both) who had not received more than two previous lines of chemotherapy. All patients were assigned to receive 300 mg olaparib twice a day for 4 weeks, followed by a combination of 300 mg olaparib twice daily and durvalumab 1.5 g via intravenous fusion every 4 weeks. The primary outcomes of the study were safety, tolerability, and 12-week disease-control rate.

Of 34 patients, 11 (32%) experienced grade-3 or worse adverse events, including anemia (12%), neutropenia (9%), and pancreatitis (6%). No treatment-related deaths were reported during the trial. Three patients (9%) discontinued the treatment due to adverse events. A total of 24 patients (80%) had disease control at 12 weeks.

The research concluded that olaparib-durvalumab combination therapy demonstrated promising antitumor activity with good safety and tolerability.