From design to clinic: Engineered peptide nanomaterials for cancer immunotherapy

Nanocarriers for cutting-edge cancer immunotherapies

Cancer immunotherapy aims to harness the body's own immune system for effective and long-lasting elimination of malignant neoplastic tissues. Owing to the advance in understanding of cancer pathology and immunology, many novel strategies for enhancing immunological responses against various cancers have been successfully developed, and some have translated into excellent clinical outcomes. As one promising strategy for the next generation of immunotherapies, activating the multi-cellular network (MCN) within the tumor microenvironment (TME) to deploy multiple mechanisms of action (MOAs) has attracted significant attention. To achieve this effectively and safely, delivering multiple or pleiotropic therapeutic cargoes to the targeted sites of cancerous tissues, cells, and intracellular organelles is critical, for which numerous nanocarriers have been developed and leveraged. In this review, we first introduce therapeutic payloads categorized according to their predicted functions in cancer immunotherapy and their physicochemical structures and forms. Then, various nanocarriers, along with their unique characteristics, properties, advantages, and limitations, are introduced with notable recent applications in cancer immunotherapy. Following discussions on targeting strategies, a summary of each nanocarrier matching with suitable therapeutic cargoes is provided with comprehensive background information for designing cancer immunotherapy regimens.

Tailoring nanovectors for optimal neoantigen vaccine efficacy

The primary objective of neoantigen vaccines is to elicit a robust anti-tumor immune response by generating neoantigen-specific T cells that can eradicate tumor cells. Despite substantial advancements in personalized neoantigen prediction using next-generation sequencing, machine learning, and mass spectrometry, challenges remain in efficiently expanding neoantigen-specific T cell populations in vivo. This challenge impedes the widespread clinical application of neoantigen vaccines. Nanovector-based neoantigen delivery systems have emerged as a promising solutions to this challenge. These nanovectors offer several advantages, such as enhanced stability, targeted intracellular delivery, sustained release, and improved antigen-presenting cell (APC) activation. Notably, they effectively deliver various neoantigen vaccine formulations (DC cell-based, synthetic long peptide (SLP)-based or DNA/mRNA-based) to APCs or T cells, thereby activating both CD4+ T and CD8+ T cells. This ultimately induces a specific anti-tumor immune response. This review focuses on recent innovations in neoantigen vaccine delivery vectors. We aim to identify optimal design parameters for vectors tailored to different neoantigen vaccine types, with an emphasis on enhancing the tumor microenvironment and stimulating the production of neoantigen-specific cytotoxic T cells. By maximizing the potential of these delivery systems, we aim to accelerate the clinical translation of neoantigen nanovaccines and advance cancer immunotherapy.

Highly Efficient Bifunctional Peptides for Tumor Immunotherapy by Simultaneously Activating T Cells and Blocking PD-L1 Immune Checkpoint

Immune checkpoint inhibitors represented by PD-1/PD-L1 monoclonal antibodies have shown great success in tumor immunotherapy. However, the response rate of immune checkpoint blockade (ICB) therapy alone is far from satisfactory due to insufficient and exhausted tumor-infiltrating T cells. Meanwhile, antibody-based drugs have some drawbacks such as high cost and complicated preparation, which require further development of nonantibody immune checkpoint inhibitors and more rational strategies for improving the effectiveness of tumor treatment. Here, a highly efficient bifunctional peptide (Bi-pep) was constructed for tumor treatment by simultaneously activating T cells and blocking the PD-L1 immune checkpoint. This peptide not only can block the PD-1/PD-L1 immunosuppressive pathway but also directly and efficiently promote the activation and proliferation of T cells, thereby showing a significant effect on promoting T cell killing of tumor cells. The Bi-pep-induced antitumor effect was verified on both subcutaneous and orthotopic tumor models, which can significantly inhibit tumor growth and thus prolong the survival of tumor-bearing mice, holding great potential for biomedical applications.

Applications of cell penetrating peptide-based drug delivery system in immunotherapy

Cell penetrating peptides (CPPs) are usually positive charged peptides and have good cell membrane permeability. Meanwhile, CPPs are facile to synthesize, and can be functionalized to satisfy different demands, such as cyclization, incorporating unnatural amino acids, and lipid conjugation. These properties have made them as efficient drug-delivery tools to deliver therapeutic molecules to cells and tissues in a nontoxic manner, including small molecules, DNA, siRNA, therapeutic proteins and other various nanoparticles. However, the poor serum stability and low tumor targeting ability also hindered their broad application. Besides, inappropriate chemical modification can lead to membrane disruption and nonspecific toxicity. In this paper, we first reviewed recent advances in the CPP applications for cancer therapy via covalent or non-covalent manners. We carefully analyzed the advantages and disadvantages of each CPP modifications for drug delivery. Then, we concluded the recent progress of their clinical trials for different diseases. Finally, we discussed the challenges and opportunities CPPs met to translate into clinical applications. This review presented a new insight into CPPs for drug delivery, which could provide advice on the design of clinically effective systemic delivery systems using CPPs.

Vaccine Therapies for Prostate Cancer: Current Status and Future Outlook

Prostate cancer is a prevalent cancer in elderly men, and immunotherapy has emerged as a promising treatment approach in recent years. The aim of immunotherapy is to stimulate the body's immune system to target and destroy cancer cells. Cancer vaccines that are highly specific, safe, and capable of creating long-lasting immune responses are a key focus in cancer immunotherapy research. Despite progress in clinical trials showing positive results, the practical use of cancer vaccines still encounters various obstacles. The complexity of the immune microenvironment and variations in the immune systems of individual patients have hindered the progress of research on prostate cancer vaccines. This review examines the history and mechanisms of cancer vaccines, summarizes recent clinical research findings, and explores future directions in the development of prostate cancer vaccines.

Antiviral fibrils of self-assembled peptides with tunable compositions

The lasting threat of viral pandemics necessitates the development of tailorable first-response antivirals with specific but adaptive architectures for treatment of novel viral infections. Here, such an antiviral platform has been developed based on a mixture of hetero-peptides self-assembled into functionalized β-sheets capable of specific multivalent binding to viral protein complexes. One domain of each hetero-peptide is designed to specifically bind to certain viral proteins, while another domain self-assembles into fibrils with epitope binding characteristics determined by the types of peptides and their molar fractions. The self-assembled fibrils maintain enhanced binding to viral protein complexes and retain high resilience to viral mutations. This method is experimentally and computationally tested using short peptides that specifically bind to Spike proteins of SARS-CoV-2. This platform is efficacious, inexpensive, and stable with excellent tolerability.