Pseudotyped βvβ6 integrin-targeted adenovirus vectors for ovarian cancer therapies

Encouraging results from recent clinical trials are revitalizing the field of oncolyticvirotherapies. Human adenovirus type 5 (HAdV-C5/Ad5) is a common vector for itsease of manipulation, high production titers and capacity to transduce multiple celltypes. However, effective clinical applications are hindered by poor tumor-selectivityand vector neutralization. We generated Ad5/kn48 by pseudotyping Ad5 with thefiber knob domain from the less seroprevalent HAdV-D48 (Ad48). The vector wasshown to utilize coxsackie and adenovirus receptor (CAR) but not CD46 for cell entry.A 20-amino acid peptide NAVPNLRGDLQVLAQKVART (A20) was inserted into the Ad5.Luc HI loop (Ad5.HI.A20) and Ad5/kn48 DG loop (Ad5/kn48.DG.A20) to target aprognostic cancer cell marker, avβ6 integrin. Relative to the Ad5.Luc parent vector, Ad5.HI.A20, Ad5.KO1.HI.A20 (KO1, ablated CAR-binding) and Ad5/kn48.DG.A20showed ~ 160-, 270-and 180-fold increased transduction in BT-20 breast carcinomacells (αvβ6high). Primary human epithelial ovarian cancer (EOC) cultures derivedfrom clinical ascites provided a useful ex vivo model for intraperitoneal virotherapy.Ad5.HI.A20, Ad5.KO1.HI.A20 and Ad5/kn48.DG.A20 transduction was ~ 70-, 60-and 16-fold increased relative to Ad5.Luc in EOC cells (αvβ6high), respectively. A20vectors transduced EOC cells at up to ~ 950-fold higher efficiency in the presenceof neutralizing ovarian ascites, as compared to Ad5.Luc. Efficient transduction andenhanced cancer-selectivity via a non-native avβ6-mediated route was demonstrated,even in the presence of pre-existing anti-Ad5 immunity. Consequently, avβ6-targetedAd vectors may represent a promising platform for local intraperitoneal treatment ofovarian cancer metastases.