Abstract P3-14-08: Preclinical efficacy of targeting c-MET by ARQ197 in combination with PARP inhibitor plus standard cytotoxic agent in triple-negative breast cancer cell lines

Abstracts: Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium; December 8-12, 2015; San Antonio, TX Background : Triple-negative breast cancer (TNBC), accounts for 15% of all invasive breast cancers (BCs) and has the poorest survival outcome of all BC subtypes. Due to its heterogeneity, TNBC lacks validated therapeutic targets compared with other BC subtypes (Sohn et al., 2014; Foulkes et al., 2010). Therefore, improved approaches to treatment of these cancers are unmet needed. Several molecular targets including: epidermal growth factor receptor (EGFR), poly ADP ribose polymerase (PARP), and hepatocyte growth factor receptor (c-MET) are under clinical investigation for the treatment of this disease (De et al., 2014; Cleator et al., 2007). The MET oncogene encodes a membrane-bound tyrosine kinase implicated in the formation and/or progression of several cancer types including TNBC, and several studies have shown c-Met overexpression to be an independent predictor of poor outcome in BC (Ho-Yen et al., 2014), c-MET may play a critical role in the development of the most aggressive BCs and may be a rational therapeutic target (Graveel et al., 2009). Currently inhibitors targeting c-MET (including ARQ197) are undergoing clinical trials in a variety of cancers including TNBC (Gaule et al., 2014; ClinicalTrials.gov). Recently, PARP inhibitors in combination with chemotherapy, has shown promising results in TNBC in clinical and preclinical studies (Tutt et al., 2010; De et al., 2014). We argue that, blocking the PARP-mediated nuclear machinery for repairing DNA-damage in presence of cytotoxic DNA damaging agents in conjunction with co-targeting c-Met pathway dependent downstream effectors may have a robust anti-tumor activity in TNBC cell lines. Methodology : BT-20 ( PIK3CA mutated, H1047R), HCC70 ( PTEN null), HCC1937 ( PTEN null), MDA-MB-231 ( KRAS/BRAF mutated), MDA-MB-468 ( PTEN null) and SUM149PT ( BRCA1 mutated) cells were used for this study. Growth inhibition, survival/proliferation, colony formation and apoptosis were examined using MTT assay, 2D proliferative /growth assay, 3D-ON-TOP assays, and annexinV staining respectively. Results : 1) For all TNBC cell lines, the IC50 of single agent ARQ197 was from 0.5 µM to 1.5 µM (following 96 hours treatment) 2) ARQ197 as a single agent or in combination with ABT888 or in triple combination dose dependently decreased cell growth/proliferation 3) annexin V positive cells were increased following treatment with single agent ARQ197 or in combination with ABT888 or in triple combination 4) 70-99% anti-proliferative activities were observed on 3D-ON TOP colony formation assay with ARQ197 alone or in combination in all tested cell lines. Conclusion: Our preclinical in vitro drug sensitivity data suggest that administration of c-MET inhibitor may enhance the antitumor activity of PARP inhibitor plus standard cytotoxic agent in TNBC models. Mechanism studies are ongoing, the results of which will be presented in the meeting. Citation Format: Sun Y, Carlson JH, Lin X, De PK, Williams C, Hausman S, Dey N, Leyland-Jones BR. Preclinical efficacy of targeting c-MET by ARQ197 in combination with PARP inhibitor plus standard cytotoxic agent in triple-negative breast cancer cell lines. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-14-08.