Abstract B46: Use of a novel orthotopic ovarian cancer transplant patient derived xenograft model as a preclinical platform for bench to bedside research.

Introduction: Treatment for cancer is moving from a “one size fits all” to a personalized and targeted approach addressing the unique biology of each patients9 tumor. Preclinical research in ovarian cancer (OVCA) has relied on established cell lines that have recently been shown to have marked differences in molecular profiles when compared to ovarian tumors from the TCGA. Patient derived xenografts (PDXs) are emerging as a reliable preclinical model that can recapitulate the principal characteristics of the patients9 original tumor while remaining biologically stable while passaged in mice. We developed an orthotopic model that involves transplanting tumor directly to the fallopian tube/ovary in order to accurately study ovarian cancer tumorigenicity and metastasis in the native environment. Experimental Procedures: Fresh OVCA tumor was transplanted orthotopically to the fallopian tube/ovary of NSG 5-8 week female mice. Tumor growth was followed over time with ultrasound. Tumors were evaluated by IHC, genomic and proteomic analysis. Alu II probe staining was performed to evaluate human stroma content. DNA sequencing analysis was performed using a 153 ovarian cancer gene panel, which includes all genes relevant to OVCA, including homologous recombination and all actionable genes. Reverse Phase Protein Array Analysis (RPPA) was used to evaluate signaling pathway activation. Several primary ovarian tumor cultures were also developed from the patients9 tumor for mechanistic studies. Results: To date, we have transplanted tumor from 18 primary, 4 interval, and 6 recurrent ovarian debulking surgeries using an orthotopic ovarian tumor transplant approach with an 90% success rate in generating tumors in mouse passage 1 (MP1) and 100% in generating MP2 and MP3. The mean time for tumors to reach ~1 cm (first passage in mice) was 8 weeks and ~6 weeks when tumors were then passaged again (MP2/MP3). We have generated 12 BRCA1/2 deleterious mutation positive carrier PDXs. Alu staining of PDXs demonstrated human cells in the stroma. We have generated several primary tumor cell lines from the original tumors/PDXs. These primary cells express ovarian epithelial markers CK7, and PAX8. Targeted DNA sequencing analysis showed that P53 and BRCA1/2 pathogenic mutations were highly conserved from the patient tumor, to the PDXs (MP1-3) and primary tumor cell lines. We evaluated 280 phospho/total proteins in our tumor samples by RPPA. Unsupervised cluster analysis of 24 patient tumors and correlating PDX (MP1-3) and 6 cell lines showed that several parent tumors clustered together with their MP1-3 PDXs. WO-2-1 BRCA 2 mutant PDXs were sensitive to platinum treatment demonstrating a response similar to that noted in the original patient after platinum chemotherapy. Conclusions: Although technically more challenging the orthotopic transplantation technique is feasible in generating ovarian cancer PDX models that more closely resemble the natural environment for ovarian cancer tumor growth and metastasis. PDXs maintain consistent gene alterations and signaling pathway activation to the original patient tumor. Given PDXs maintain the characteristics of the patients9 original tumor, they are excellent models to study therapeutic response. Citation Format: Erin George, Hyoung Kim, Clemens Krepler, Janos Tanyi, Zhi Wei, Katrin Sproesser, Patricia Brafford, Marilda Beqiri, Adina-Monica Vultur, Rachel Lee, Mark Morgan, Ronny Drapkin, Tan Ince, Meenhard Herlyn, Fiona Simpkins. Use of a novel orthotopic ovarian cancer transplant patient derived xenograft model as a preclinical platform for bench to bedside research. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B46.