Cancer remains one of the leading causes of death worldwide, emphasizing the urgent need for innovative and effective therapeutic strategies. Among emerging modalities, personalized cancer vaccines (PCVs) have attracted significant attention as a prom...
Cancer remains one of the leading causes of death worldwide, emphasizing the urgent need for innovative and effective therapeutic strategies. Among emerging modalities, personalized cancer vaccines (PCVs) have attracted significant attention as a promising immunotherapeutic approach capable of eliciting patient-specific immune responses against tumor-associated mutations. However, several critical challenges, including the identification of highly immunogenic neoantigens, enhancement of vaccine-induced T cell responses, and strategies to increase anti-tumor efficacy by antigen-specific T cells, remain unresolved for successful clinical translation.
In this dissertation, a series of studies were conducted to develop and evaluate mRNA-based PCVs targeting both MHC class I- and MHC class II-restricted neoantigens in a murine colorectal cancer model. Candidate neoantigens were identified through next-generation sequencing (NGS)–based mutational profiling and in silico prediction of MHC-binding epitopes. The immunogenicity and anti-tumor efficacy of mRNA vaccines encoding MHC-I or MHC-II neoantigens were systematically examined. Co-administration of MHC-I and MHC-II antigens significantly enhanced antigen-specific CD8+ T cell responses (IFN-γ+ TNF-α+ CD8+ T cells) and improved tumor suppression compared to single-antigen vaccination. The treatment resulted in increased infiltration of CD4+ and CD8+ T cells into tumor tissues, expansion of short-lived effector CD8+ T cells, and reduction of regulatory T cells (Tregs), thereby promoting a favorable immune microenvironment.
To further evaluate therapeutic optimization, the efficacy of vaccination at different stages of tumor progression was assessed. Early-stage vaccination produced superior anti-tumor effects, reduced postoperative tumor recurrence, and induced durable memory T cell responses sustained for over 90 days. Moreover, combination therapy with immune checkpoint inhibitors (anti–PD-1 and anti–Tim-3 antibodies) exhibited synergistic tumor regression, confirming the benefit of concurrent immunomodulation. Finally, combination of the mRNA-based neoantigen vaccine with mRNA-encoded interleukin-12 (IL-12) markedly enhanced CD8+ and CD4+ T cell infiltration within tumor tissues and produced potent, synergistic anti-cancer efficacy.
Collectively, this work establishes a comprehensive preclinical framework for mRNA-based PCVs, demonstrating that (i) rapid identification of highly immunogenic neoantigens, (ii) rational co-administration of MHC-I and MHC-II antigens, and (iii) synergistic combination with cytokine or checkpoint immunotherapies represent key strategies to maximize therapeutic benefit. These findings provide mechanistic insights and translational implications for the design of next-generation personalized mRNA vaccines in precision cancer immunotherapy.