Development of a Novel CEA Expressing Adenovirus for Treatment

Jones, Frank

Abstract

The objective of this project is to continue developing an adenoviral vector vaccine against CEA that is effective in stimulating cell-mediated immunity in animals previously immune to adenovirus. The Ad-CEA vaccine endpoint is to treat patients with CEA bearing cancers. CEA is a protein that has been reported to be useful as a vaccine treatment target. Evidence indicates that a broad cell-mediated immune (CMI) response is needed to treat certain CEA bearing cancers. Adenovirus (Ad) vector vaccines induce CMI responses and have emerged as a leading candidate to be used as a treatment vaccine delivery platform. First Generation Ad vaccines have proven less effective than anticipated and adverse reactions are in question. Furthermore, pre-existing Ad immunity of most humans causes decreased effectiveness. To address these issues, we have developed an advanced Ad based vector that is devoid of early genes E1, E3, and E2b. These """"""""E2b-deleted"""""""" vectors, with deletions in the polymerase and preterminal protein genes, have an expanded cloning capacity and greatly reduced expression of viral late genes as compared to First Generation. The reduced expression of multiple Ad viral genes has been demonstrated to be advantageous for vaccine development for reasons such as reduced antigenic competition, greater longevity of expression, which provides increased immunologic stimulus and reduced adverse effects. Such advantages are important in the presence of pre-existing Ad immunity, and provide the E2b Ad vectors stealth-like attributes. The Company has exclusive license for the new Ad vector system and the E.C7 cell line that supports vector production. The proposed studies are designed to construct and test the effectiveness of CEA vaccines based on the new E2b-deleted Ad vector platform, which will carry the CEA gene. Ad vaccines will be tested for their potential to induce CEA memory CMI responses as a prime and for their re-immunization (boost) potential in Ad-na?ve and Ad- immune mice. The mice will be monitored for any adverse effects of the vaccine. This project will result in an effective, safe, easy to produce, stable, and easy to use CEA therapeutic vaccine. Our goal is to initiate a Phase I clinical trial using an Ad vector platform within a year of funding.

Public Health Relevance

During this study, we will further develop an advanced vector delivery system for an Ad- CEA treatment vaccine. The system is needed to break through the barrier presented by vaccinees that have had prior adenovirus infections which includes most humans. ? ?