Co-delivery of human cancer-testis antigens with adjuvant in protein nanoparticles induces higher cell-mediated immune responses.

Nanoparticles have attracted considerable interest as cancer vaccine delivery vehicles for inducing sufficient CD8+ T cell-mediated immune responses to overcome the low immunogenicity of the tumor microenvironment. Our studies described here are the first to examine the effects of clinically-tested human cancer-testis (CT) peptide epitopes within a synthetic nanoparticle. Specifically, we focused on two significant clinical CT targets, the HLA-A2 restricted epitopes of NY-ESO-1 and MAGE-A3, using a viral-mimetic packaging strategy. Our data shows that simultaneous delivery of a NY-ESO-1 epitope (SLLMWITQV) and CpG using the E2 subunit assembly of pyruvate dehydrogenase (E2 nanoparticle), resulted in a 25-fold increase in specific IFN-γ secretion in HLA-A2 transgenic mice. This translated to a 15-fold increase in lytic activity toward target cancer cells expressing the antigen. Immunization with a MAGE-A3 epitope (FLWGPRALV) delivered with CpG in E2 nanoparticles yielded an increase in specific IFN-γ secretion and cell lysis by 6-fold and 9-fold, respectively. Furthermore, combined delivery of NY-ESO-1 and MAGE-A3 antigens in E2 nanoparticles yielded an additive effect that increased lytic activity towards cells bearing NY-ESO-1+ and MAGE-A3+. Our investigations demonstrate that formulation of CT antigens within a nanoparticle can significantly enhance antigen-specific cell-mediated responses, and the combination of the two antigens in a vaccine can preserve the increased individual responses that are observed for each antigen alone

Protein-Based Nanoparticles for Cancer Immunotherapy

Although progress has been made in conventional cancer therapy, cancer is still the second leading cause of death in the United States. Recently, a new approach for cancer treatment known as immunotherapy has shown remarkable success. Within immunotherapy, cancer vaccines train the body to recognize tumor-associated antigens for targeted destruction of cancer cells. While promising, clinical success of cancer vaccines to date has been limited. Our work focuses on utilizing a viral-mimetic design to develop a new platform to improve cancer vaccine efficacy. We have been exploring the non-viral E2 protein nanoparticle as a cancer vaccine platform. We verified that simultaneous delivery of cancer antigen epitopes (e.g., gp100, NY-ESO-1, MAGE-A3) and adjuvant (CpG) within E2 nanoparticles resulted in improved anti-tumor responses. Prophylactic immunization with CpG-gp-E2 (E2 conjugated with gp100 and CpG) increased animal survival time by ̴ 40% in an aggressive tumor model. Furthermore, we demonstrated that simultaneous delivery of human-restricted cancer-testis epitopes and CpG within E2 (CpG-NYESO-E2 and CpG-MAGE-E2) resulted in an increase in IFN-γ secretion and enhanced lytic activity towards human cancer cells expressing the antigen. These results demonstrate the broad efficacy of the E2 nanoparticle platform against various target cancer antigens.One of the promising new FDA-approved approaches in cancer immunotherapy is the obstruction of inhibitory effects of immune checkpoint molecules (e.g., PD-1). However, treatments with checkpoint inhibitors are still not effective in a significant portion of patients. To address this, we examined the therapeutic effects of combination delivery of anti-PD-1 with CpG-gp-E2 nanoparticles. In the B16-F10 melanoma tumor model, ̴ 50% of the mice treated with combination therapy remained tumor-free, compared with 0% and ̴ 5% survival for vaccine and anti-PD-1 treatments alone, respectively. Cell uptake of the E2 nanoparticle in vitro was also investigated, and we demonstrated that surface display of CpG on E2 increased the nanoparticle uptake by APCs, which can potentially further increase the vaccine efficacy. Altogether, our results demonstrate the potential of the E2 protein nanoparticle as an effective cancer vaccine platform for inducing anti-tumor responses. These findings could lead to more effective cancer treatments

Protein-based nanoparticles in cancer vaccine development.

Peptide and protein-based cancer vaccines usually fail to elicit efficient immune responses against tumors. However, delivery of these peptides and proteins as components within caged protein nanoparticles has shown promising improvements in vaccine efficacy. Advantages of protein nanoparticles over other vaccine platforms include their highly organized structures and symmetry, biodegradability, ability to be specifically functionalized at three different interfaces (inside and outside the protein cage, and between subunits in macromolecular assembly), and ideal size for vaccine delivery. In this review, we discuss different classes of virus-like particles and caged protein nanoparticles that have been used as vehicles to transport and increase the interaction of cancer vaccine components with the immune system. We review the effectiveness of these protein nanoparticles towards inducing and elevating specific immune responses, which are needed to overcome the low immunogenicity of the tumor microenvironment

An Antigen-Delivery Protein Nanoparticle Combined with Anti-PD-1 Checkpoint Inhibitor Has Curative Efficacy in an Aggressive Melanoma Model.

Immune checkpoint inhibition is a promising alternative treatment to standard chemotherapies; however, it fails to achieve long-term remission in a significant portion of patients. A previously developed protein nanoparticle-based platform (E2 nanoparticle) delivers cancer antigens to increase antigen-specific tumor responses. While prior work has focussed on prophylactic conditions, the objectives in this study are therapeutic. It is hypothesized that immune checkpoint inhibition, when augmented by antigen delivery using E2 nanoparticles containing CpG oligonucleotide 1826 (CpG) and a glycoprotein 100 (gp100) melanoma antigen epitope (CpG-gp-E2), would synergistically elicit antitumor responses. To identify a regimen primed for obtaining effective treatment results, immune benchmarks in the spleen and tumor are examined. Conditions that lead to significant immune activation, including increases in gp100-specific interferon gamma (IFN-?), CD8 T cells in the spleen, tumor-infiltrating CD8 T cells, and survival time are identified. Based on the findings, the resulting combination of CpG-gp-E2 and anti-programmed cell death protein 1 (anti-PD-1) treatment in tumor-challenged mice yield significantly increased long-term survival; more than 50% of the mice treated with combination therapy were tumor-free, compared with 0% and ≈5% for CpG-gp-E2 and anti-PD-1 alone, respectively. Evidence of a durable antitumor response is also observed upon tumor rechallenge, pointing to long-lasting immune memory

Viral-mimicking protein nanoparticle vaccine for eliciting anti-tumor responses.

The immune system is a powerful resource for the eradication of cancer, but to overcome the low immunogenicity of tumor cells, a sufficiently strong CD8(+) T cell-mediated adaptive immune response is required. Nanoparticulate biomaterials represent a potentially effective delivery system for cancer vaccines, as they can be designed to mimic viruses, which are potent inducers of cellular immunity. We have been exploring the non-viral pyruvate dehydrogenase E2 protein nanoparticle as a biomimetic platform for cancer vaccine delivery. Simultaneous conjugation of a melanoma-associated gp100 epitope and CpG to the E2 nanoparticle (CpG-gp-E2) yielded an antigen-specific increase in the CD8(+) T cell proliferation index and IFN-γ secretion by 1.5-fold and 5-fold, respectively, compared to an unbound peptide and CpG formulation. Remarkably, a single nanoparticle immunization resulted in a 120-fold increase in the frequency of melanoma epitope-specific CD8(+) T cells in draining lymph nodes and a 30-fold increase in the spleen, relative to free peptide with free CpG. Furthermore, in the very aggressive B16 melanoma murine tumor model, prophylactic immunization with CpG-gp-E2 delayed the onset of tumor growth by approximately 5.5 days and increased animal survival time by approximately 40%, compared to PBS-treated animals. These results show that by combining optimal particle size and simultaneous co-delivery of molecular vaccine components, antigen-specific anti-tumor immune responses can be significantly increased