Challenges and Opportunities for Effective Cancer Immunotherapies

A novel self-assembled nucleobase-nanofiber platform of CDN to activate the STING pathway for synergistic cancer immunotherapy

2', 3'-cGAMP (CDN) as cGAS-STING pathway agonist is extensively used in tumor treatment. However, due to its negatively charged nature (containing two phosphate groups) and high hydrophilicity, CDN faces challenges in crossing cell membranes, resulting in reduced efficiency of its use. Additionally, CDN is susceptible to inactivation through phosphodiesterase hydrolysis. Therefore, the development of a new drug delivery system for CDN is necessary to prevent hydrolysis and enhance targeted accumulation in tumors, as well as improve cellular uptake for STING activation. In this study, we have developed peptide-polymer nanofibers (PEG-Q11) that incorporate thymine (T) and arginine (R) residues to facilitate complexation with CDN through the principles of Watson-Crick base pairing with thymine and favorable electrostatic interactions and bidentate hydrogen bonding with arginine side chains. The entrapment efficiency (EE) of PEG-Q11T3R4@CDN was found to be 51% higher than that of PEG-Q11@CDN. Due to its favorable biocompatibility, PEG-Q11T3R4@CDN was employed for immunotherapy in mouse CT26 tumors. In local tumor treatment, the administration of PEG-Q11T3R4@CDN at a low dose and through a single injection exhibited inhibitory effects. Furthermore, the local injection of PEG-Q11T3R4@CDN resulted in systemic therapeutic responses, effectively suppressing tumor metastasis by activating CD8 + T cells to target distant tumors. This research not only underscores the potential of PEG-Q11T3R4@CDN as an efficient therapeutic agent but also highlights its ability to achieve long-lasting systemic therapeutic outcomes following local treatment. Consequently, PEG-Q11T3R4@CDN represents a promising strategy for immunization.

Bacteria-based immunotherapy for cancer: a systematic review of preclinical studies

Immunotherapy has been emerging as a powerful strategy for cancer management. Recently, accumulating evidence has demonstrated that bacteria-based immunotherapy including naive bacteria, bacterial components, and bacterial derivatives, can modulate immune response via various cellular and molecular pathways. The key mechanisms of bacterial antitumor immunity include inducing immune cells to kill tumor cells directly or reverse the immunosuppressive microenvironment. Currently, bacterial antigens synthesized as vaccine candidates by bioengineering technology are novel antitumor immunotherapy. Especially the combination therapy of bacterial vaccine with conventional therapies may further achieve enhanced therapeutic benefits against cancers. However, the clinical translation of bacteria-based immunotherapy is limited for biosafety concerns and non-uniform production standards. In this review, we aim to summarize immunotherapy strategies based on advanced bacterial therapeutics and discuss their potential for cancer management, we will also propose approaches for optimizing bacteria-based immunotherapy for facilitating clinical translation.

Emerging applications of cancer bacteriotherapy towards treatment of pancreatic cancer

Pancreatic cancer is a highly aggressive form of cancer with a five-year survival rate of only ten percent. Pancreatic ductal adenocarcinoma (PDAC) accounts for ninety percent of those cases. PDAC is associated with a dense stroma that confers resistance to current treatment modalities. Increasing resistance to cancer treatments poses a challenge and a need for alternative therapies. Bacterial mediated cancer therapies were proposed in the late 1800s by Dr. William Coley when he injected osteosarcoma patients with live streptococci or a fabrication of heat-killed Streptococcus pyogenes and Serratia marcescens known as Coley's toxin. Since then, several bacteria have gained recognition for possible roles in potentiating treatment response, enhancing anti-tumor immunity, and alleviating adverse effects to standard treatment options. This review highlights key bacterial mechanisms and structures that promote anti-tumor immunity, challenges and risks associated with bacterial mediated cancer therapies, and applications and opportunities for use in PDAC management.

Therapeutic tumor vaccines — a rising star to benefit cancer patients

Malignant tumors are still a worldwide threat to human health. Tumor treatment strategies are constantly evolving, and the advent of tumor immunotherapy has brought up hope to many types of tumors, especially for those that are refractory to conventional therapies including surgery, radiotherapy, and chemotherapy. Tumor vaccines can initiate or amplify an anti-tumor immune response in tumor patients through active immunization, and therefore occupy an important position in tumor immunotherapy. The main types of tumor vaccines include tumor cell vaccines, dendritic cell vaccines, polypeptide vaccines and nucleic acid vaccines. Due to factors such as poor antigen selection and suppressive tumor microenvironment, earliest tumor vaccines on clinical trials failed to achieve satisfactory clinical effects. However, with the development of second-generation genome sequencing technologies and bioinformatics tools, it is possible to predict neoantigens generated by tumor-specific mutations and therefore prepare personalized vaccines. This article summarizes the global efforts in developing tumor vaccines and highlights several representative tumor vaccines in each category.

A Review on Cancer Immunotherapy and Applications of Nanotechnology to Chemoimmunotherapy of Different Cancers

Clinically, different approaches are adopted worldwide for the treatment of cancer, which still ranks second among all causes of death. Immunotherapy for cancer treatment has been the focus of attention in recent years, aiming for an eventual antitumoral effect through the immune system response to cancer cells both prophylactically and therapeutically. The application of nanoparticulate delivery systems for cancer immunotherapy, which is defined as the use of immune system features in cancer treatment, is currently the focus of research. Nanomedicines and nanoparticulate macromolecule delivery for cancer therapy is believed to facilitate selective cytotoxicity based on passive or active targeting to tumors resulting in improved therapeutic efficacy and reduced side effects. Today, with more than 55 different nanomedicines in the market, it is possible to provide more effective cancer diagnosis and treatment by using nanotechnology. Cancer immunotherapy uses the body's immune system to respond to cancer cells; however, this may lead to increased immune response and immunogenicity. Selectivity and targeting to cancer cells and tumors may lead the way to safer immunotherapy and nanotechnology-based delivery approaches that can help achieve the desired success in cancer treatment.