However, the impact of pre-existing anti-Ad5 neutralizing antibodies on OAd5-mediated transgene expression and antitumor effects in tumor-bearing hosts has not been fully evaluated because there are no appropriate mouse models in which the impact of anti-Ad5 neutralizing antibodies on both OAd5-meditated transgene expression and OAd5-meditated antitumor effects can be simultaneously evaluated. This evidence concerns the gene PSEN2 and neoplasm.