Abstract 5401: TGF-β signaling inhibition as a potential approach to target suboptimally debulked ovarian tumors

Abstract

Abstract The current standard of care for all patients with high-grade, advanced-stage serous ovarian cancer is surgery followed by adjuvant chemotherapy. Resection of all visible residual disease to less than 1 cm is associated with a favorable prognosis, but this optimal debulking can only be achieved in ∼70% of patients. Patients with suboptimal cytoreduction are presumed to have lower response rates to subsequent chemotherapy and are known to have a poor prognosis. Recently, we performed a meta-analysis of 1,525 publicly available expression profiling assays and identified a 200-gene expression signature of primary ovarian tumors to predict the outcome of debulking surgery. The signature was validated using two independent sets of tumors. This debulking signature consists of transcripts positively regulated by TGF-β, indicating that hyperactivation of TGF-β signaling may be responsible of the aggressive biological and clinical behavior of suboptimally debulked tumors. In this study, we evaluated the potential anti-tumor effect of TGF-β signaling blockade in ovarian cancer cells in vitro and in vivo. Integrated TGF-β signaling was observed in 8 of 10 ovarian cancer cell lines tested by a SMAD-binding element based luciferase assay. The potential anti-tumor effect of a small molecular TGFBR1 kinase inhibitor LY2157299 was further investigated in SKOV3 cell line, which presents both endogenous and inducible TGF-β signaling and is highly disseminative when inoculated into immunodeficient mice. Although imposing minimum effect on in vitro cellular proliferation, LY2157299 significantly inhibited tumor-dissemination related biological processes in SKOV3 cells including migration, invasion and mesothelial cell adhesion. In an interperitoneal SKOV3 xenograft model, administration of LY2157299 significantly increased cisplatin related cytotoxicity and tumor burden reduction. Taken together, our study has provided evidence for the potential clinical use of LY2157299 to improve the treatment and survival of women with suboptimal surgery. Citation Format: Wei Wei, Michael J. Birrer. TGF-β signaling inhibition as a potential approach to target suboptimally debulked ovarian tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5401. doi:10.1158/1538-7445.AM2015-5401