Multifunctional nano-vaccines integrating lipid-conjugated tumor antigens with TLR/STING agonists enhance cancer immunotherapy.

Although there are several ongoing clinical trials using neoantigen peptide-based cancer vaccines, challenges still exist to implement in clinical approval such as poor antigen stability, inefficient delivery, and inadequate immune activation. To address these limitations, we developed a polymer-based polyvalent peptide and adjuvant (SPPA) that co-delivers lipid-conjugated tumor-specific peptides with Toll-like receptor 7/8 (3M - 052) and a STING (2'3'-cGAMP) agonist. This nanoplatform enables efficient peptide encapsulation, sustained release, and targeted delivery to antigen-presenting cells (APCs), thereby enhancing both innate and adaptive immune responses. We synthesized and characterized a library of lipid-conjugated tumor-associated and neoantigenic peptides. In vitro, SPPA significantly upregulated pro-inflammatory genes and cytokine secretion, confirming robust innate immune activation and demonstrated effective cellular uptake and lymphatic trafficking. In vivo, SPPA alone or in combination with anti-PD-1 antibody (αPD-1) elicited strong cytotoxic T lymphocyte (CTL) responses and inhibited tumor growth in four aggressive syngeneic mouse models: Triple-negative breast cancer (4T1), HER2+ breast cancer (TUBO), lung carcinoma (LLC1), and renal cell carcinoma (RENCA). The combination therapy led to pronounced tumor growth inhibition, survival benefit, and immune cell infiltration, including elevated CD8+IFN-γ+ T cells and M1 macrophages, and reduced regulatory T cells and MDSCs. Spatial transcriptomics revealed localized transcriptional reprogramming, with downregulation of extracellular matrix genes and activation of inflammatory pathways. Collectively, these findings establish SPPA as a potent and versatile nanovaccine platform capable of inducing durable antitumor immunity, especially when combined with immune checkpoint blockade. This approach offers strong translational potential for personalized immunotherapy across diverse solid tumor types.