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Volume 3 Supplement 2

30th Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2015)

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The generation and analysis of a novel combination of recombinant adenovirus vaccines targeting three tumor antigens as an immunotherapeutic

We have reported on a novel adenovirus serotype 5 (Ad5) vector gene delivery platform (Ad5 [E1-, E2b-]), in which regions of the early 1 (E1), early 2 (E2b), and early 3 (E3) genes have been deleted. The unique deletions in this platform result in a dramatic decrease in late gene expression, leading to a marked reduction in host immune response to the vector. CEA, MUC1, and brachyury are tumor-associated antigens (TAA) expressed on a wide range of human tumors. Ad5 [E1-, E2b-]–CEA vaccine (ETBX-011) has been employed in clinical studies as an active vaccine to induce immune responses to CEA in metastatic colorectal cancer patients. The Ad5 [E1-, E2b-]–CEA vector encodes the entire CEA sequence modified to express an enhancer T-cell epitope. We report here the development of novel Ad5 [E1-, E2b-]–brachyury and Ad5 [E1-, E2b-]–MUC-1 vaccine constructs. The Ad5 [E1-, E2b-]–brachyury vector was constructed to encode the entire brachyury gene devoid of 25 amino acids involved in DNA binding, and modified to express an enhancer T cell epitope. The Ad5 [E1-, E2b-]–MUC-1 vector was constructed to encode the entire MUC-1 transgene with eight agonist epitopes, including five in the C-terminus. Our results show that these constructs (CEA, MUC1 and brachyury) are capable of activation, as well as generation of antigen specific T cells in vitro, and of inducing antigen-specific T cells in vaccinated mice. We have also demonstrated that the use of a combination of the three vaccines (designated Tri-Ad5) displays little, if any, antigenic competition in in vitro studies of human dendritic cells for antigen-specific T cell activation and generation, or in murine vaccination studies. The studies reported here support the rationale for the application of Tri-Ad5 as a therapeutic modality to induce immune responses to a diverse range of human TAAs for potential clinical studies.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Tsang, K.Y., Gabitzsch, E.S., Palena, C. et al. The generation and analysis of a novel combination of recombinant adenovirus vaccines targeting three tumor antigens as an immunotherapeutic. j. immunotherapy cancer 3 (Suppl 2), P452 (2015). https://doi.org/10.1186/2051-1426-3-S2-P452

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  • DOI: https://doi.org/10.1186/2051-1426-3-S2-P452

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