Neural Stem Cell Mediated Delivery of AR2011 Oncolytic Virus for Ovarian Cancer.

DIANA MACHADO; RACHAEL MOONEY; JENNIFER BATALLA COVELLO; MOHAMED HAMMAD; LOPEZ, MARIA VERONICA; OSVALDO L PODHAJCER; DAVID T CURIEL; KAREN ABOODY

Chicago

Congreso; 21th Annual Meeting of the American Society of Gene & Cell Thera; 2018

American Society of Gene & Cell Thera

Ovarian cancer is the most lethal gynecologic malignancy, afflicting approximately 22,000 women per year in the U.S. Once it has metastasized to the abdominal cavity (stage III), patients have only a 34% 5-year survival rate following standard treatment with surgical debulking and combination chemotherapy. Oncolytic virotherapy is a promising novel approach that can induce cancer cell death irrespective of radio- or chemoresistance, and also stimulate immune system recognition of cancer cells by exposing tumor antigens upon lysis. Although clinical trials to date have demonstrated safety, the efficacy of this approach has been limited by delivery hurdles including rapid inactivation by the immune system, poor viral penetration of tumors, and an inability of the virus to effectively reach invasive metastatic foci separated by normal tissue. Inherently tumor-tropic neural stem cells (NSCs) have the ability to penetration metastases, making them an ideal cell carrier to overcome these hurdles. In particular, the clonal human NSC line used here (HB1.F3.CD21) enables reproducible viral loading, non-immunogenicity, and chromosomal stability, with demonstrated clinical safety in first-in-human brain tumor trials. We previously reported NSC distribution to peritoneal ovarian metastases in an immunodeficient model. We now demonstrate NSC distribution to intraperitoneal (IP) ID8.Renilla.eGFP ovarian cancer metastases in a C59Bl/6 immunocompetent mouse model. This allows us to assess their ability to provide protection from immune-mediated viral clearance and neutralization, while selectively delivering oncolytic viruses to ovarian tumor foci. The oncolytic adenovirus used in these studies, AR2011, replicates under the control of the Secreted Protein Acidic Rich in Cysteine (SPARC) promoter. SPARC is overexpressed not only in tumor cells, but also in tumor-associated stroma, enabling efficient viral spread throughout the tumor and its microenvironment. AR2011 also contains enhancer elements that respond to tumor conditions of hypoxia and inflammation. Significant tumor killing of ID8 ovarian cancer cells was observed in vitro after 5 days of co-culture with NSC.AR2011 (at a ratio of 1000:1). NSCs also protected the oncolytic activity of AR2011 when cultured in the presence of ovarian cancer patient ascites fluid, which was confirmed to have neutralizing antibodies against adenovirus. For in vivo NSC biodistribution studies, NSC.qtracker 605, or NSC.qtracker 655 were injected IP. Two days later, 3D block-face cryo-images of harvested mice were created to visualize NSC biodistribution. For oncoviral efficacy studies, 5E6 of either NSC.AR2011 or free AR2011 were administered IP weekly for 3 weeks, with cisplatin and no treatment controls, and followed for long-term survival, monitoring tumor progression with serial BLI. In vivo results demonstrate IP NSC.AR2011 seeding of virus at the majority of established ovarian tumor metastases. Viral distribution was confirmed via IHC and qPCR. Comparative in vivo efficacy studies are in progress, with and without a PD-L1 checkpoint inhibitor to potentially enhance the oncolytic virotherapy with an additional immune component. We expect NSC-mediated AR2011 treatment +/- PD-L1 antibody to improve long-term survival as compared to standard of care chemotherapy regimens, without the associated off-target toxicities. We aim to demonstrate preclinical efficacy and safety, to streamline this NSC.AR2011 approach to clinical trials for in patients suffering from stage III ovarian cancer.