Delivery of nucleic acids (e.g. genes or RNAi) to combat metastatic ovarian cancer is a highly promising therapeutic approach. Tumor cells may be killed by nucleic acids encoding either pro-apoptotic factors or enzymes that can convert prodrugs into toxic molecules. Invariably, however, the success of any gene therapy approach hinges on the ability to deliver the nucleic acid-based effector molecules to target tumors with high specificity and efficiency, a feat that has been largely difficult to achieve. Most vector targeting approaches to date have relied on cell surface receptors overexpressed on some subpopulation of target cancer cells. Unfortunately, there is no unique cell surface biomarker that specifically identifies all cells in a tumor. To overcome this limitation, we propose to develop a platform of protease-activatable viral vectors that we call Provectors. The Provectors cannot deliver transgenes until they become activated by extracellular proteases present at high levels in ovarian tumor microenvironments. In particular, the Provectors are designed to detect matrix metalloproteinases (MMPs), such as MMP-2 and MMP-9, whose overexpression is correlated to ovarian cancer progression and death. Our Provector technology is based on the clinically promising adeno-associated virus (AAV), which has recently been approved as the first human gene therapy product in Europe. We have key pilot data demonstrating our ability to build Provectors whose transduction capabilities are activated by MMPs. In an orthotopic ovarian cancer model, a Provector prototype is able to significantly increase transgene delivery and expression in tumors with decreased off-target delivery to liver and spleen. Furthermore, after just a single intravenous injection of Provector encoding HSV-tk, metastatic ovarian tumor bearing mice treated with ganciclovir had significantly better therapeutic outcomes compared to controls. The proposed project will support the design and characterization of the 2nd generation of Provectors with improved features and enable further in vivo testing.
In specific aim 1, we will construct a modular platform of high efficiency Provectors for targeting metastatic ovarian tumors.
In specific aim 2, we will characterize the developed Provectors via a panel of in vitro assays. Finally, in specific aim 3, we will test the performance of Provectors in preclinical models of ovarian cancer. The proposed project, if successful, will generate a suite of protease-activatable Provectors with improved properties that can target and eradicate metastatic ovarian tumors in vivo.

Public Health Relevance

As contemporary biomedical research efforts continue to identify a long list of genes as potential targets for therapeutic intervention of cancer, the next generation of biological therapies for cancer treatment may be nucleic acid-based. The proposed platform technology aims to achieve both high efficiency and specificity of nucleic acid delivery to ovarian tumors. The central goal of the work is to develop biological therapies for cancer treatment that are more effective and less toxic by constructing stimulus-responsive and potentially patient-specific nucleic acid delivery technologies.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Gene and Drug Delivery Systems Study Section (GDD)
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Welch, Anthony R
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Rice University
Biomedical Engineering
Biomed Engr/Col Engr/Engr Sta
United States
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Chen, Maria Yanqing; Butler, Susan S; Chen, Weitong et al. (2018) Physical, chemical, and synthetic virology: Reprogramming viruses as controllable nanodevices. Wiley Interdiscip Rev Nanomed Nanobiotechnol :e01545
Brun, Mitchell J; Gomez, Eric J; Suh, Junghae (2017) Stimulus-responsive viral vectors for controlled delivery of therapeutics. J Control Release 267:80-89