Phase I/Ib Study Of The Parp Inhibitor (Parpi) Olaparib (O) With Carboplatin (C) In Triple Negative Breast Cancer (Tnbc) At Low Genetic Risk (Nct00647062)

Background: PARPi O demonstrates single agent activity in breast and ovarian cancer (Br/OvCa) pts with germline BRCA1/2 mutation (gBRCAm), and with BRCA-like phenotype. Subsets of TNBC are known to respond to therapies targeting DNA repair mechanisms. We hypothesize that O and C combination can be safely tolerated in TNBC pts and may result in benefit. Methods: Pts with recurrent or unresectable TNBC, BRCAPro score Results: 25 women (median age 52 [39-76]) were treated. All pts except one received prior therapy (median 5 [0-12]; prior platinum in 3pts). DLT was thrombocytopenia (DL 2: O 400mg/C AUC4 [1/6pts] and DL3: O 400mg/C AUC 5 [2/3pts]). MTD was reached at DL3 (C/AUC 5 with O 400mg capsule q12h d1-7 q21d). The expansion dose was O 400mg q12h d1-7, C/AUC 4. Gr 3/4 AEs included neutropenia (36%), thrombocytopenia (12%), and anemia (12%). 2 pts required C dose reduction and early discontinuation due to delayed marrow recovery. 13 pts (52%) needed peg-filgrastim, 6 (24%) blood transfusion, and 3 (12%) erythropoietin on at least one cycle. Responses (N=22 evaluable) included 1 CR (46+ mo), 2 PR (3, 5 mo), and 8 with SD ≥4 mo (36%; median 5 [4-7]), for a disease control rate of 50%. The pt who achieved CR had a strong family history of Br/OvCa. Peripheral blood mononuclear cells preC1, d3 or d7, and prior to C2 were collected for PAR incorporation ELISA. Paired tumor biopsies (pre/post-cycle1) were obtained from expansion cohort patients for biomarker proteomics and apoptosis endpoints; results will be presented. Conclusions: RP2D O capsule formulation 400 mg q12h d1-7 with C AUC4 q21d is tolerable in heavily pretreated TNBC pts. Interactive marrow suppression was observed. Citation Format: Victoria L. Chiou, Elise C. Kohn, Christina M. Annunziata, Lori Minasian, JoAnne Zujewski, Minshu Yu, Jay Ji, James Doroshow, Nicolas Gordon, Nicole Houston, Jung-Min Lee. Phase I/Ib study of the PARP inhibitor (PARPi) olaparib (O) with carboplatin (C) in triple negative breast cancer (TNBC) at low genetic risk (NCT00647062). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT337. doi:10.1158/1538-7445.AM2014-CT337