Analyses of Recombinant Vaccinia and Fowlpox Vaccine Vectors Expressing Transgenes for Two Human Tumor Antigens and Three Human Costimulatory Molecules

Abstract

Purpose: The poor immunogenicity of tumor antigens and the antigenic heterogeneity of tumors call for vaccine strategies to enhance T-cell responses to multiple antigens. Two antigens expressed noncoordinately on most human carcinomas are carcinoembryonic antigen (CEA) and MUC-1. We report here the construction and characterization of two viral vector vaccines to address these issues. Experimental Design: The two viral vectors analyzed are the replication-competent recombinant vaccinia virus (rV-) and the avipox vector, fowlpox (rF-), which is replication incompetent in mammalian cells. Each vector encodes the transgenes for three human costimulatory molecules (B7-1, ICAM-1, and LFA-3, designated TRICOM) and the CEA and MUC-1 transgenes (which also contain agonist epitopes). The vectors are designated rV-CEA/MUC/TRICOM and rF-CEA/MUC/TRICOM. Results: Each of the vectors is shown to be capable of faithfully expressing all five transgenes in human dendritic cells (DC). DCs infected with either vector are shown to activate both CEA- and MUC-1–specific T-cell lines to the same level as DCs infected with CEA-TRICOM or MUC-1-TRICOM vectors. Thus, no evidence of antigenic competition between CEA and MUC-1 was observed. Human DCs infected with rV-CEA/MUC/TRICOM or rF-CEA/MUC/TRICOM are also shown to be capable of generating both MUC-1- and CEA-specific T-cell lines; these T-cell lines are in turn shown to be capable of lysing targets pulsed with MUC-1 or CEA peptides as well as human tumor cells endogenously expressing MUC-1 and/or CEA. Conclusion: These studies provide the rationale for the clinical evaluation of these multigene vectors in patients with a range of carcinomas expressing MUC-1 and/or CEA.

Combination Chemotherapy and Radiation of Human Squamous Cell Carcinoma of the Head and Neck Augments CTL-Mediated Lysis

“…These vaccines are presently in phase II and phase III clinical trials. They consist of recombinant poxviruses expressing the transgenes CEA and MUC-1 and three T-cell costimulatory molecules (57). The patient could then undergo definitive combination chemotherapy with CDDP and 5-FU concurrent with external-beam radiation (bolus or fractionated doses).…”

Vesicular Stomatitis Virus-Based Therapeutic Vaccination Targeted to the E1, E2, E6, and E7 Proteins of Cottontail Rabbit Papillomavirus

“…Alternatively or in addition, reduced efficacy may have resulted from antigenic competition among the antigens of coexpressed CRPV proteins. Several mechanisms for antigenic competition have been described, including competition for antigen uptake by antigen-presenting cells (APCs), competition of APCs for (in this case) T-helper type 1-related cytokines, and competition of T cells, including T regulatory cells, for physical access to limited numbers of APCs (16,19,41). Future studies could determine whether superior efficacy could be achieved by vaccinating different sites with different VSV-based CRPV vectors to avoid antigenic competition, as in other studies (33).…”

The Human T-Box Mesodermal Transcription Factor Brachyury Is a Candidate Target for T-Cell–Mediated Cancer Immunotherapy

“…CD8 + T cells negatively isolated from T-cell cultures were used as effector cells at various effector-to-target (E:T) cell ratios. When target cells were C1R-A2 or T2, cocultures were incubated at 37jC in a 5% CO 2 atmosphere for 6 h as previously described (20); when carcinoma cell lines were used as targets, cocultures were incubated as previously described (20) in the same conditions for a period of 16 h. Cytotoxic assays employing normal donor CD19 + B cells as targets were conducted for 5 h as previously described (21) due to the high levels of spontaneous release observed after a 16-h incubation period. Supernatants were harvested, and the…”