Harnessing Vaccines in the Treatment of Solid Tumors: Advances, Challenges, and Future Directions

Immunotherapy has become a cornerstone of cancer treatment in both the early and advanced setting in recent years, leading to the achievement of substantial and durable responses with an excellent safety profile across different tumor types. This demonstrates the high potential of engaging the immune system in the treatment of solid tumors. Consequently, there has been renewed interest in vaccines to enhance therapeutic effects, prevent tumor development, and eliminate or control minimal residual disease. Although therapeutic cancer vaccines have shown potential benefits in certain settings, their results in clinical trials remain highly variable and generally unsatisfactory, depending on tumor site, biology, and vaccine type. Currently, Sipuleucel-T for prostate cancer is the only cell-based vaccine that received FDA approval for the treatment of a solid tumor. Innovative techniques such as personalized neoantigen vaccines and mRNA-based vaccines have shown promising preclinical and early-phase clinical results, supporting their further development. Despite the current evidence of vaccine efficacy in treating solid tumors being derived from only a few clinical trials with relatively small sample sizes, ongoing trials are also exploring innovative approaches aimed at preventing cancer development or enhancing immune responses in combination with other immunotherapeutic agents. In this review, we provide an overview of the clinical results and the current state of vaccine development for cancer treatment, outlining future perspectives on their role in managing patients with cancer.