Talazoparib Maintenance Therapy in Triple-negative Breast Cancer

The investigators propose a randomized phase II clinical trial of talazoparib maintenance therapy in TNBC patients whose tumor showed clinical benefit (platinum-sensitivity) to first- or second-line platinum-based chemotherapy (monotherapy or combination with other agents). Patients are eligible when they meet at least one of two following platinum-sensitivity criteria: 1. They should have received 6 tri-weekly doses or 18 weekly doses of platinum-based therapy in non-progression status (at least stable disease) at the time of enrollment; 2. They should remain in complete or partial response status after 4-6 tri-weekly doses or 12-18 weekly doses of platinum-based chemotherapy. Eligible patients are enrolled to the trial within 4 to 8 weeks after last chemotherapy and 1:1 randomized to receive talazoparib versus placebo maintenance therapy. The primary endpoint is PFS by RECIST 1.1 after randomization. The secondary endpoints include OS, time from randomization to second progression or death (PFS2), and objective response rate (ORR) by RECIST 1.1, adverse events by CTCAE 5.0 criteria, quality of life evaluated by EORTC-QLQ-C30, and EuroQoL EQ-5D.