title: Anti-tumor immunotherapy despite immunity to adenovirus using a novel adenoviral vector Ad5 [E1-, E2b-]-CEA.
abstract: Adenovirus serotype 5 (Ad5) has been widely used in clinical trials because it expresses inserted transgenes robustly and augments the innate immune response. Strategies to improve Ad5 vectors that can circumvent Ad5 immunity have become a critical issue, especially for use as a cancer immunotherapeutic in which repeated immunization is required. In this study, we constructed a novel Ad5 vector with unique deletions of the viral DNA polymerase and the pre-terminal protein region (Ad5 [E1-, E2b-]). This vector contains the carcinoembryonic antigen (CEA) gene insert and is designed to induce cell-mediated immunity (CMI) against the tumor-associated target. The CEA immunogenicity and in vivo anti-tumor effects of repeated immunizations with Ad5 [E1-, E2b-]-CEA compared with those observed with current generation Ad5 [E1-]-CEA were tested in Ad5 pre-immunized mice. We report that Ad5-immune mice immunized multiple times with Ad5 [E1-, E2b-]-CEA induced CEA-specific CMI responses that were significantly increased over those detected in Ad5-immune mice immunized multiple times with a current generation Ad5 [E1-]-CEA. Ad5 immune mice bearing CEA-expressing tumors that were treated with Ad5 [E1-, E2b-]-CEA had increased anti-tumor response as compared with Ad5 [E1-]-CEA treated mice. These results demonstrate that Ad5 [E1-, E2b-]-CEA can induce CMI immune responses which result in tumor growth inhibition despite the presence of pre-existing Ad5 immunity. Multiple re-immunizations using the same vector platform are now possible with the novel Ad5 [E1-, E2b-] platform.
authors.affiliation: Etubics Corporation, Seattle, WA 98119, USA. beth@etubics.com
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Gabitzsch
authors.forename: Younong
authors.initials: Y
authors.lastname: Xu
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Balint
authors.forename: Zachary C
authors.initials: ZC
authors.lastname: Hartman
authors.forename: H Kim
authors.initials: HK
authors.lastname: Lyerly
authors.forename: Frank R
authors.initials: FR
authors.lastname: Jones
mesh_terms: D000256:Adenoviridae / Q000235:genetics* / Q000276:immunology; D017498:Adenovirus E1 Proteins / Q000235:genetics; D017502:Adenovirus E2 Proteins / Q000235:genetics; D000818:Animals; D019496:Cancer Vaccines / Q000008:administration & dosage / Q000276:immunology; D002272:Carcinoembryonic Antigen / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D045744:Cell Line, Tumor; D017353:Gene Deletion; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D006801:Humans; D007114:Immunization / Q000379:methods; D007167:Immunotherapy / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D017498:Adenovirus E1 Proteins; D017502:Adenovirus E2 Proteins; D019496:Cancer Vaccines; D002272:Carcinoembryonic Antigen