Nanoplex cluster-mediated synergistic modulation of dendritic cells and T cells amplifies tumor-specific adaptive immunity

Abstract

Tumor immune evasion is greatly impacted by immune checkpoint molecules that impede the activation of costimulatory signals. Inadequate costimulatory molecules restrict the immune system's capacity to generate strong responses to malignancies. This study presents a development of a dual-nanoplex cluster (NC) formulation that effectively overcomes these issues. The formulation comprises a nanoplex (NP) encapsulating CpG ODN 1826 (CpG NP), which stimulates TLR-9 and elevates the levels of CD80/86 costimulatory molecules on antigen-presenting cells, and a NP incorporating CTLA-4 siRNA (siCTLA-4 NP), which suppresses the production of the immunological checkpoint molecule CTLA-4 on T cells. The two NPs undergo a cycloaddition reaction involving azide groups (AZ) on the NPs and alkyne groups at both termini of an MMP-2-cleavable peptide (APA) to produce a NC. The NC formation process is modulated to fabricate a flexible and deformable architecture with optimized size that maximizes passive melanoma accumulation while maintaining systemic stability, exhibiting intratumoral cleavability and substantial tumor suppression efficacy. Ex-vivo study of cell composition in spleens and tumors, along with tumor-specific antigen stimulation assays on splenocytes, suggests that NC treatment can switch the immunosuppressive tumor microenvironment into an immunocompetent state. These findings demonstrate that our NC formulation, which integrates CTLA-4 suppression with DC stimulation, potentiates immune responses against tumor tissues, providing novel insights and potential applications in the field of cancer immunotherapy.