Dendritic cells in cancer immunotherapy: functional barriers, reprogramming strategies and translational challenges.

Cancer immunotherapy depends on effective antigen presentation and T cell activation. Antigen-presenting cells (APCs), especially dendritic cells (DCs), play a central role in this process by capturing tumor antigens, processing them, and presenting antigenic peptides to T cells through major histocompatibility complex molecules. However, APC function is often impaired within the tumor microenvironment. Reduced antigen presentation, weak co-stimulatory signaling, suppressive cytokines, metabolic stress, and inhibition by myeloid-derived suppressor cells and regulatory T cells all limit effective antitumor immunity. These defects contribute to immune escape and reduce the efficacy of current immunotherapies. In this mini review, we summarize the key roles of APCs in antitumor immune responses and discuss major APC-based therapeutic strategies, including dendritic cell vaccines, nanoparticle-based antigen delivery, mRNA vaccine platforms, DC-targeted delivery systems, and oncolytic virus-based combinations. We also highlight functional reprogramming approaches that aim to restore APC activity through innate immune activation, blockade of immunosuppressive cytokines, and metabolic regulation. Although these strategies have shown strong potential, their clinical translation remains limited by tumor antigen heterogeneity, complex manufacturing, poor immune infiltration, and persistent immunosuppression in the tumor microenvironment. Future APC-based immunotherapy should move beyond single antigen presentation enhancement and focus on integrated immune remodeling. Rational combinations with immune checkpoint blockade, innate immune agonists, radiotherapy, chemotherapy, and biomarker-guided patient selection may help generate stronger and more durable antitumor responses.