The endocytosis-mediating performances of two types of peptide ligands, cell receptor binding peptide (CRBP) and cell membrane penetrating peptide (CMPP), were analyzed and compared using a common carrier of peptide ligands-human ferritin heavy chain (hFTH) nanoparticle. Twenty-four copies of a CMPP(human immunodeficiency virus-derived TAT peptide) and/or a CRBP (peptide ligand with strong and specific affinity for either human integrin(α β ) or epidermal growth factor receptor I (EGFR) that is overexpressed on various cancer cells) were genetically presented on the surface of each hFTH nanopariticle. The quantitative level of endocytosis and intracellular localization of fluorescence dye-labeled CRBP- and CMPP-presenting nanoparticles were estimated in the in vitro cultures of integrin- and EGFR-overexpressing cancer and human dermal fibroblast cells(control). From the cancer cell cultures treated with the CMPP- and CRBP-presenting nanoparticles, it was notable that CRBPs resulted in quantitatively higher level of endocytosis than CMPP (TAT) and successfully transported the nanoparticles to the cytosol of cancer cells depending on concentration and treatment period of time, whereas TAT-mediated endocytosis localized most of the nanoparticles within endosomal vesicles under the same conditions. These novel findings provide highly useful informations to many researchers both in academia and in industry who are interested in developing anticancer drug delivery systems/carriers.

Although anti-cancer vaccination and immune checkpoint (IC) therapy have emerged as potent cancer treatment modalities, their application remains limited to a subset of patients due to vaccine adjuvant toxicities and IC-blocking antibody-associated systemic immune adverse events. Here, an innovative platform is reported for adjuvant-and antibody-free cancer immunotherapy using human heavy chain ferritin (huHF)-derived optimally designed structures presenting multiple-copies of tumor-specific antigens (TSAs) or IC molecules (ICMs) on their surface. Through structure-guided molecular design, TSA-presenting huHFs for targeting TSAs at dendritic cells (DCs) are constructed with preservation of huHF-intrinsic affinity for transferrin receptors on DCs, and multi-copies of an ICM are also presented on huHF for blocking a cognate regulatory IC. The adjuvant-free co-administration of TSA-and ICM-presenting huHFs effectively elicits TSA-specific CD8+ T cell activation, strikingly suppresses both tumor growth and interleukin 17+ CD4+ T cell responses, and generates long-lasting protective immunity, indicating that this novel approach offers a promising breakthrough in cancer immunotherapy.

Although protein nanoparticles (PNPs) (e.g., viral capsids) capable of delivering a broad range of drug agents have shown distinctive advantages over synthetic nanomaterials, PNPs have an intrinsic drawback that hampers their clinical application, that is, potential immunogenicity. Here, a novel method for resolving the immunogenicity problem of PNPs, which is based on the genetic presentation of albumin‐binding peptides (ABPs) on the surface of PNP, is reported. ABPs are inserted into the surface of a viral capsid (hepatitis B virus capsid/HBVC) while preserving the native self‐assembly function of HBVC. The ABPs effectively gather human serum albumins around HBVC and significantly reduce both inflammatory response and immunoglobulin titer in live mice compared to ABP‐free HBVC. Furthermore, ABP‐conjugated HBVCs remain within tumors for a longer period than HBVCs conjugated to tumor cell receptor‐bindingpeptides, indicating that the ABPs are also capable of enhancing tumor‐targeting performance. Although applied to HBVC for proof of concept, this novel approach may provide a general platform for resolving immunogenicity and cancer‐targeting problems of PNPs, which enables the development of a variety of PNP‐based drug delivery carriers with high safety and efficacy.

Cancer chemotherapeutic drugs such as doxorubicin, mitomycin C, and gemcitabine, which are mostly small synthetic molecules, are still clinically useful for cancer treatment. However, despite considerable therapeutic efficacy, severe toxicity-associated problems, which are mainly caused by the non-specific mode of action such as chromosomal DNA damage and interference in the DNA replication even in normal cells, remain unresolved and a major challenge for safer and thus more widespread adoption of chemotherapy. Herein, an innovative platform is developed through beneficially integrating core peptide units into highly-ordered, stable, and flexibly guest-adaptable structure of apoferritin, which simultaneously fulfills high-capacity loading of chemotherapeutic drugs compared with the case of FDA-approved antibody-drug conjugates, efficient drug targeting to cancer cells, and cancer cell-specific drug release and activation. This approach dramatically reduces drug toxicity to normal cells, significantly enhances efficacy in in vivo cancer treatment without toxicity to normal organs of mice, and thus is expected to open up a novel clinical route to break through the limits of current cancer chemotherapy.

Accumulating data have highlighted the role of monocytes/macrophages in immune escape by generating immunologically "cold" tumors that do not respond to immunotherapy. CD244 (SLAMF4, 2B4), a member of the signaling lymphocyte activation molecule family, is expressed on myeloid cells, but its precise role has not been elucidated. Using monocyte lineage-specific CD244-deficient (LysM-cre+/-CD244fl/fl;cKO) mice challenged with B16F10 melanoma, we report for the first time that CD244 negatively regulates tumor immunity by inhibiting the differentiation and functional maturation of CD11b+Ly6ChiF4/80lo monocytes into CD11b+Ly6CloF4/80hi macrophages within the tumor microenvironment. CD244-deficient macrophages more effectively activated antigen-specific T cell responses compared to WT macrophages, thus delaying tumor growth in the B16F10 melanoma model. Moreover, combinatorial intervention of anti-PD-L1 antibodies with CD244-KO BMDM markedly improved tumor rejection compared to the anti-PD-L1 antibody alone or in combination with WT BMDM. Consistent with the murine data, transcriptome analysis of human melanoma tissue single-cell RNA-sequencing dataset (SCP398 from single-cell portal), revealed 221 differentially expressed genes of CD244- monocytes/macrophages were associated with phagocytosis, antigen presentation, and autophagy. Additionally, cell type deconvolution analysis within melanoma patients bulk RNA-seq datasets from TCGA database, revealed presence of CD244- monocytes/macrophages significantly increased patient survival in primary and metastatic tumors. Hence, we proposed that CD244 serve as a critical immune checkpoint receptor on macrophages, and CD244-deficient macrophages may represent a novel therapeutic modality to convert immunologically "cold" tumors to "hot" tumors, which can function synergistically with checkpoint blockade therapies.