Gene Transfer to Ovarian Cancer Versus Normal Tissues with Fiber-Modified Adenoviruses

Abstract

Adenovirus serotype 5 (Ad5) displays unparalleled gene transfer efficacy to cells with high coxsackie-adenovirus receptor (CAR) expression. Unfortunately, cells isolated from clinical human cancers, both ovarian and other types, express highly variable and often low levels of CAR. Fortunately, native Ad5 tropism can be modified to circumvent CAR deficiency and to enhance infectivity. Ad5/3luc1 incorporates the serotype 3 fiber knob and binds to a receptor distinct from CAR, while the fiber of Ad5lucRGD is modified with an RGD-4C motif, allowing CAR-independent binding to integrins. We studied the liver tropism and blood clearance of these viruses after intravenous (i.v.) injection, and biodistribution after intraperitoneal (i.p.) injection to tumor-bearing mice. To estimate efficacy, we assessed gene transfer to purified human primary ovarian cancer cells, and in a mouse model of ovarian cancer. Ad5/3luc1 achieved improved gene transfer over Ad5lucRGD, and both infectivity-enhanced viruses were superior to the isogenic control with an unmodified Ad5 capsid. In the presence of malignant ascites, gene transfer was improved with both Ad5/3luc1 and Ad5lucRGD. Thus, retargeting to the Ad3 receptor enhances gene transfer to clinically relevant ovarian cancer substrates, while the mouse toxicity and biodistribution profile of both fiber-modified Ad vectors is comparable to Ad5.

CAR is a cell–cell adhesion protein in human cancer cells and is expressionally modulated by dexamethasone, TNFα, and TGFβ

“…A Brüning and IB Runnebaum applied retargeting of adenoviral vectors to integrins, 26,28,29 independent of CAR expression and its localization, can be a promising tool for more efficient gene transfer efficiencies into human cancer cells. Application of cytokines enhancing expression of CAR and integrins preferentially with anti-tumoral activity can contribute to a better therapeutic efficacy in gene therapeutic applications.…”

Complex mosaicism is a novel approach to infectivity enhancement of adenovirus type 5-based vectors

“…In addition, serotype chimerism has been demonstrated to accomplish CAR-independent entry with infectivity enhancement. 5,9,11,12 The most recent additional approach has employed a combination of two different functional ligands genetically incorporated in two distinct locales of a single-fiber knob. This approach has proved to be useful as it has allowed an additional infectivity enhancement of the Ad5 vector due to the additive effect of dual-receptor targeting via both ligands within a single fiber molecule.…”

Transductional targeting of adenovirus vectors for gene therapy

“…67 Subgroup D Ad receptors include CD46 and a(2-3)-linked sialic acid, a common element of glycolipids. [71][72][73] This fiber pseudotyping approach has identified chimeric vectors with superior infectivity to Ad5 in several clinically relevant cell types, including primary ovarian carcinoma cells, [74][75][76] 81 human cardiovascular tissue 82 and others. 83,84 Interestingly, this strategy has been extended to exploit fiber elements from non-human Ads 85,86 and the fiber-like s1 reovirus attachment protein, which targets cells expressing junctional adhesion molecule.…”