Abstract AS25: An adeno-associated virus (AAV) 9 vector delivering modified human mullerian inhibiting substance (MIS) as a gene therapy for ovarian cancer

Abstract

Abstract Purpose: Ovarian cancer is the most lethal malignancy of the female reproductive tract; as such, effective treatments are needed to improve patient survival. MIS has previously been shown to inhibit growth of a stem-like subset of the total cell population in ovarian cancer cell lines (Wei et al, 2010; Meirelles et al, 2012). We have recently engineered novel peptide modifications to human MIS (LR-MIS), which increase production and potency in vitro and in vivo (Pepin et al, 2013), and inserted it into an AAV vector. AAV delivered gene therapy has undergone a clinical resurgence with a good safety profile and sustained gene expression (Zhang et al, 2011). Therefore, we assessed the efficacy of a single intraperitoneal (ip) dose of AAV9-LR-MIS to inhibit tumor growth of an established cell line for subsequent evaluation in patient-derived ovarian cancer xenografts (PDX). Methods: 6 week old female nude mice were treated with a single ip injection of 3e11 or 1e12 virions of AAV9 LR-MIS or GFP. Serum levels of human MIS were monitored weekly by ELISA. After serum steady state was achieved, the established ovarian cancer cell line, OVCAR5 was xenografted subcutaneously at 1e6 cells per animal. Tumors treated with AAV were measured twice weekly. Additionally, Patient ascites were processed to isolate the cancer cell population, which was specifically amplified in vitro to create low passage primary cell lines. Results: AAV9-LR-MIS treatment resulted in elevated and sustained blood concentrations of MIS (Fig1A) in nude mice without any signs of toxicity, and significantly inhibited OVCAR5 tumor growth (p=0.0003) (Fig1B) in two separate experiments. AAV9-GFP revealed that the pancreas, omentum, gut mesentery, and body wall muscles were the primary sites of infection. Treatment with MIS induced downregulation of CCND1 in tumors. A panel of 15 primary ovarian cancer cell lines, all expressing the MIS type II receptor were generated from patient ascites and cells are being tested for their ability to grow as PDX in Nude, NOD/SCID, and NSG mice. Figure 1.AAV-LR-MIS treatment results in stable expression of MIS and inhibition of tumor growth of OVCAR5 xenografts. A) Weekly MIS ELISA of serum from mice after single doses of 1e10 to 1e12 virions. B) Tumor growth of 1e6 OVCAR5 cells xenografted into nude mice (N=5) pretreated with 3e11/mouse (1.5e13/kg) LR-MIS or GFP virus (p=0.0003 by two-way ANOVA).Figure 1. AAV-LR-MIS treatment results in stable expression of MIS and inhibition of tumor growth of OVCAR5 xenografts. A) Weekly MIS ELISA of serum from mice after single doses of 1e10 to 1e12 virions. B) Tumor growth of 1e6 OVCAR5 cells xenografted into nude mice (N=5) pretreated with 3e11/mouse (1.5e13/kg) LR-MIS or GFP virus (p=0.0003 by two-way ANOVA). Conclusions: AAV9 virally delivered human LR-MIS can produce adequate sustained levels of MIS that inhibited the growth of the human ovarian cancer cell line, OVCAR 5. AAV9 LR MIS provides a well-tolerated, low toxicity treatment of ovarian cancer, which can now be evaluated in a phase 0 trial using PDX models being prepared from human ovarian cancer ascites. Citation Format: David Pepin, Amanda Sosulski, Katherine Hendren, Li Hua Zhang, Fotini Nicolaou, Dan Wang, Guangping Gao, Patricia K Donahoe. An adeno-associated virus (AAV) 9 vector delivering modified human mullerian inhibiting substance (MIS) as a gene therapy for ovarian cancer [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS25.