Abstract 126: Dasatinib attenuates Src pathway signaling and combined with veliparib and carboplatin potently inhibits tumor growth in PTEN-null TNBC model

Abstract

Abstract Background: The combination of a poly ADP ribose polymerase (PARP) inhibitor with a DNA-damaging agent has shown promise in treating triple-negative breast cancer (TNBC); but not all patients respond to this combination. The Src protein kinase modulates multiple cancer cell properties and plays a key role in tumorigenic processes. However, Src inhibitors as single agents have shown limited effects in solid tumors. In this study, we examined the antitumor effects of the Src inhibitor dasatinib, the PARP inhibitor veliparib, and the DNA-damaging agent carboplatin in PTEN-null TNBC cells in vitro and tumors in vivo to try to identify the combination with the most clinical potential. Methods: The PTEN-null TNBC cell line, MDA-MB-468, was used in this study. For in vitro studies, proliferation, cellular apoptosis, and 3D on-top clonogenic growth were measured, tube formation assays and western blot analysis were performed. For in vivo studies, a xenograft model was used to examine treatment responses, and immunohistochemical analysis was performed. Results: Interestingly, treatment with the combination of veliparib plus carboplatin led to an increase in Src phosphorylation of MDA-MB-468 cells. Importantly, addition of dasatinib attenuated Src overexpression induced by veliparib plus carboplatin and further increased the activation of caspase 3 and PARP, thereby enhancing the antitumor efficacy of veliparib plus carboplatin. In an MDA-MB-468 xenograft model, the triple combination of dasatinib with veliparib plus carboplatin showed greater tumor growth inhibitory effects compared with single agents or double combinations. No systemic toxicity was observed in mice treated with the triple combination. Conclusion: Here, we provide novel evidence that veliparib combined with carboplatin drives Src activation in the preclinical model tested. Moreover, we provide provocative in vitro and in vivo data highlighting the potential for increasing therapeutic efficacy by combining dasatinib with veliparib and carboplatin in PTEN-null TNBC. Citation Format: Yuliang Sun, Xiaoqian Lin, Jennifer Aske, Casey Williams, Mark Abramovitz, Brian Leyland-Jones. Dasatinib attenuates Src pathway signaling and combined with veliparib and carboplatin potently inhibits tumor growth in PTEN-null TNBC model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 126.