Efficacy Of The Parp Inhibitor (Pi) Abt-888 (Veliparib [Vel]) Either With Carboplatin (Carb) Or As A Single Agent Followed By Post-Progression Therapy In Combination With Carb In Patients (Pts) With Brca1- Or Brca2-(Brca)-Associated Metastatic Breast Cancer (Mbc).

520 Background: Based on the concept of synthetic lethality combining platinum agents and PIs should benefit patients (pts) with BRCA-associated MBC. We report mature outcomes with vel alone, or with carb. Methods: Pts with germline BRCA-associated MBC, ECOG performance status of ≤ 2, without prior PI treatment were included. In phase I the maximum tolerated dose (MTD) of carb (AUC of 5) IV every 21 days, and vel 150 mg BID were defined. In phase II, pts received vel 400 mg BID and upon progression, carb and vel at the MTD. Results: Between 6/2010 and 4/2014, 72 evaluable pts (28 in phase I, 44 in phase II) with BRCA1 (34 patients) or BRCA2 (37 patients) mutations (1 pt had both) and with MBC were enrolled. The median age was 44-years (range; 28-68); 49% of pts had hormone receptor + MBC. Pts received a median of 1 (0 – 5) prior chemo-regimen for MBC. Response rate (RR) for the 28 pts in phase I was 50% [CR rate 18%] and 2 pts remain in CR at 43+ and 34+ cycles, both are on vel maintenance, alone; median ...