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MP63-19 IMMUNOGENICITY INVESTIGATION ON RECOMBINANT BCG CONTAINING NY-ESO-1 UPON VACCINATION

INTRODUCTION AND OBJECTIVES: Bladder cancer is one of the most common malignant tumors in the urinary system. Intravesical instillation of BCG has been proved to reduce the recurrence of bladder cancer and prevents the progression of cancer, which in turn improves survival rate and prolongs survival time. However, repetitive irrigation of large-dose BCG leads to various complications. Moreover, 30%-50% patients have low responses to BCG therapy, limiting its clinical applications in bladder cancer. In this study, we have introduced NY-ESO-1, a well-known tumor antigen, into BCG to construct recombinant BCG stains (rBCG::NY-ESO-1). The immunogenicities of the rBCG strains were evaluated in mouse vaccination model. METHODS: Human-derived NY-ESO-1 cDNA was amplified and inserted into the shuttle expression vector pMV261. The recombinant plasmids pMV261-NY-ESO-1 were transformed into BCG by electroporation. The recombinant BCG strains were screened and the expression of NY-ESO-1 was verified by Western blot. The C57BL/6 mice were immunized by subcutaneous injection with rBCG:NY-ESO-1 and BCG at a dose of 5×10^6 CFU per 100µl. Immunological profiles were evaluated at 4 weeks by Enzyme-linked Immunospot Assay (ELISPOT) and flow cytometry (FCM). RESULTS: One-dose injection of rBCG::NY-ESO-1 induced both PPD and NY-ESO-1 specific IFN&ggr; release upon antigen stimulation ex vivo whereas BCG vaccination induced comparable PPD-specific responses and less NY-ESO-1-specific responses. In addition, rBCG vaccinated mice displayed more effect CD8+ T cells and NY-ESO-1-specific IFN&ggr;+CD8+ T cells. Meanwhile, both NY-ESO-1 and PPD-specific IL-10 producing CD8+T cells were decreased in rBCG::NY-ESO-1 vaccinated mice when compared to BCG vaccinated group. Mice vaccinated with rBCG showed less frequencies of Treg at 4 weeks post vaccination. CONCLUSIONS: Vaccination of rBCG containing NY-ESO-1 can induce both PPD and NY-ESO-1 specific cellular responses where NY-ESO-1 specific CD8 T cells exhibit more functional effects. Introduction of NY-ESO-1 into BCG thus orchestrates NY-ESO-1-specific immune responses and immune modulator of BCG, which might increase the efficacy of intravesical instillation of BCG against bladder cancer. Source of Funding: none