Ovarian carcinoma cells are often infected inefficiently by adenoviruses (Ad) due to low expression of coxsackie-adenovirus receptors (CAR), hindering the application of adenovirus-mediated gene therapy in ovarian cancer. In this study, we explored a class of infectivity-enhanced Ad vectors, which contain CAR-independent targeting motifs RGD (Ad5.RGD), polylysine (Ad5.pK7), or both (Ad5.RGD.pK7), for their utility in ovarian cancer gene therapy using in vitro and in vivo model systems. We found that these vectors infected established ovarian carcinoma cell lines and primary ovarian cancer cells with significantly enhanced infectivity. Among them, Ad5.RGD.pK7 appeared to be most efficient. Further, we evaluated their gene delivery efficiency using two different ovarian cancer mouse models - subcutaneous and intraperitoneal human ovarian cancer xenografts. All of the modified vectors appeared to be more efficient than the unmodified Ad5 vector in both models, although some of the differences are not statistically significant. Of these, Ad5.RGD.pK7 exhibited the highest efficacy in the subcutaneous tumor model, while Ad5.pK7 worked most efficiently in the intraperitoneal tumor model. These preclinical results suggest that Ad5.RGD.pK7 and Ad5.pK7 may be very useful in ovarian cancer gene therapy. © 2004 Nature Publishing Group All rights reserved.