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.

PDL1-targeted vaccine exhibits potent antitumor activity by simultaneously blocking PD1/PDL1 pathway and activating PDL1-specific immune responses.

Despite the clinical success of immune checkpoint blockade, only a subset of people exhibits durable responses, suggesting that an alternative immunotherapeutic strategy is required. This paper reported a two-in-one cancer vaccine that targets programmed death ligand 1 (PDL1) that blocks the PD1/PDL1 pathway and also activates antitumor immune response. The PDL1- NitraTh vaccine, which consists of the extracellular domain of PDL1 and nitrated T cell epitope, effectively broke the immune tolerance of PDL1 and elicited PDL1-specific humoral and cellular immunity. The treatment of PDL1-NitraTh exhibited potent antitumor activity. Moreover, immunization of PDL1 vaccine increased the infiltration of tumor lymphocytes and decreased the proportion of Treg cells in tumor tissues, suggesting that the vaccine may remodel the tumor microenvironment. The upregulation of PDL1 in tumor tissues was induced by PDL1-NitraTh vaccine but not in spleen and lymphomas. This upregulation of PDL1 is beneficial to the antitumor activity of PDL1-specific humoral and cellular immunity induced by PDL1-NitraTh. In summary, PDL1-targeted vaccine exhibits potent antitumor activity and may provide an alternative immunotherapy strategy for patients who are not sensitive to PDL1 antibody drugs.

Efficient Acquisition of Fully Human Antibody Genes against Self-Proteins by Sorting Single B Cells Stimulated with Vaccines Based on Nitrated T Helper Cell Epitopes.

Single B cell antibody technology is a method for isolating antigen-specific B cells from human peripheral blood and obtaining antibody genes in developing antibody drugs. However, owing to immune tolerance to autoantigen, human autoantigen-specific B cells are difficult to acquire by conventional single B cell technology. In this study, we constructed a nitrated T-cell epitope named NitraTh by incorporating p-nitrophenylalanine into a universal T helper epitope. NitraTh had enhanced ability to activate CD4+ T cells and can be recognized by CD4+ T cells with different HLA class II haplotypes. This NitraTh can also break immune tolerance to autoantigens, such as human epidermal growth factor receptor 2 (HER2) and cannabinoid receptor 1, and induce strong specific IgM+ B cell responses in vitro. HER2-NitraTh vaccine can also stimulate the generation of HER2-specific IgG+ B cells in human immune system mice, which was established by cotransplanting lymphocytes and autologous dendritic cells in immunodeficient mice. We obtained 30 fully human IgG antibody genes by sorting single B cells from the human immune system mice immunized with HER2-NitraTh vaccine. The analysis of antibody genes showed that sorted B cells underwent the extensive somatic mutation of the antibody genes. We randomly selected eight genes for cloning, six of which expressed antibodies that can bind to HER2. Hence, we provided a convenient and effective method in acquiring fully human antibody genes against self-proteins, which can be used in developing therapeutic antibody drugs.