Altered epitopes enhance macrophage-mediated anti-tumour immunity to low-immunogenic tumour mutations.

Personalized neoantigen therapy has shown long-term and stable efficacy in specific patient populations. However, not all patients have sufficient levels of neoantigens for treatment. Although somatic mutations are commonly found in tumours, a significant portion of these mutations do not trigger an immune response. Patients with low mutation burdens continue to exhibit unresponsiveness to this treatment. We propose a design paradigm for neoantigen vaccines by utilizing the highly immunogenic unnatural amino acid p-nitrophenylalanine (pNO2Phe) for sequence alteration of somatic mutations that failed to generate neoepitopes. This enhances the immunogenicity of the mutations and transforms it into a suitable candidate for immunotherapy. The nitrated altered epitope vaccines designed according to this paradigm is capable of activating circulating CD8+ T cells and inducing immune cross-reactivity against autologous mutated epitopes in different MHC backgrounds (H-2Kb, H-2Kd, and human HLA-A02:01), leading to the elimination of tumour cells carrying the mutation. After immunization with the altered epitopes, tumour growth was significantly inhibited. It is noteworthy that nitrated epitopes induce tumour-infiltrating macrophages to differentiate into the M1 phenotype, surprisingly enhancing the MHC II molecule presenting pathway of macrophages. Nitrated epitope-treated macrophages have the potential to cross-activate CD4+ and CD8+ T cells, which may explain why pNO2Phe can enhance the immunogenicity of epitopes. Meanwhile, the immunosuppressive microenvironment of the tumour is altered due to the activation of macrophages. The nitrated neoantigen vaccine strategy enables the design of vaccines targeting non-immunogenic tumour mutations, expanding the pool of potential peptides for personalized and shared novel antigen therapy. This approach provides treatment opportunities for patients previously ineligible for new antigen vaccine therapy.

Self-assembled nanoparticles based on DNA origami and a nitrated T helper cell epitope as a platform for the development of personalized cancer vaccines.

Neoantigen vaccines constitute an emerging and promising cancer immunotherapy. However, not all neoantigens have anti-tumor activity, as poor CD4+ epitope recognition can lead to the lack of greatly limit the persistence of the CD8+ T cell response. Therefore, we designed a self-assembled nanoplatform hereinafter referred to as DNA-coupled nitrated T helper cell epitope nanoparticle (DCNP) based on DNA origami containing a nitrated CD4 + T cell epitope, which can facilitate the effective activation of neoantigen-specific CD8+ T cells. Moreover, we embedded the cytidine-phosphate-guanosine oligonucleotide (CpG ODN) motif sequence in the DNA skeleton to function as a built-in adjuvant to activate Toll-like receptor 9. DCNP can markedly improve adjuvant and neoantigen co-delivery to lymphoid organs and promote neoantigen presentation on dendritic cells. Moreover, DCNP induced robust, and long-lived neoantigen-specific CD8+ T cell responses that significantly delayed tumor growth. Further, these effects were largely dependent on the nitrated T cell epitope. Collectively, our findings indicate that DCNP is a promising platform that could improve the development of personalized therapeutic neoantigen vaccines for cancer immunotherapy.