LIGHT protein suppresses tumor growth by augmentation of immune response

Combination of LIGHT (TNFSF14)-Armed Myxoma Virus Pre-Loaded into ADSCs and Gemcitabine in the Treatment of Experimental Orthotopic Murine Pancreatic Adenocarcinoma

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is a weakly immunogenic fatal neoplasm. Oncolytic viruses have dual anti-cancer properties including tumor-lysing and immune response-boosting effects and offer attractive alternative for PDAC management. Adipose-derived stem cells (AD-SCs) of mesenchymal origin were infected ex vivo with recombinant oncolytic myxoma virus (MYXV), which encodes murine LIGHT, also called tumor necrosis factor ligand superfamily member 14 (TNFSF14). ADSC-shielded virus were administered into murine pancreatic cancer lesions that had been induced orthotopically in immunocompetent mice. Ensuing oncolysis and the activation of anti-tumor immune responses provided significant survival benefit. Although adjunct therapy with gemcitabine improved the cytolytic killing of pancreatic cancer cells in vitro, it induced no additional survival advantage in this model in vivo.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a deadly neoplasm. Oncolytic viruses have tumorolytic and immune response-boosting effects and present great potential for PDAC management. We used LIGHT-armed myxoma virus (vMyx-LIGHT) loaded ex vivo into human adipose-derived mesenchymal stem cells (ADSCs) to evaluate murine PDAC treatment in conjunction with gemcitabine (GEM). The cytotoxicity of this treatment was confirmed in vitro using human and murine pancreatic cancer cell cultures, which were more sensitive to the combined approach and largely destroyed. Unlike cancer cells, ADSCs sustain significant viability after infection. The in vivo administration of vMyx-LIGHT-loaded ADSCs and gemcitabine was evaluated using immunocompetent mice with induced orthotopic PDAC lesions. The expression of virus-encoded LIGHT increased the influx of T cells to the tumor site. Shielded virus followed by gemcitabine improved tumor regression and survival. The addition of gemcitabine slightly compromised the adaptive immune response boost obtained with the shielded virus alone, conferring no survival benefit. ADSCs pre-loaded with vMyx-LIGHT allowed the effective transport of the oncolytic construct to PDAC lesions and yielded significant immune response; additional GEM administration failed to improve survival. In view of our results, the delivery of targeted/shielded virus in combination with TGF-β ablation and/or checkpoint inhibitors is a promising option to improve the therapeutic effects of vMyx-LIGHT/ADSCs against PDAC in vivo.

Systemic Delivery of mLIGHT-Armed Myxoma Virus Is Therapeutic for Later-Stage Syngeneic Murine Lung Metastatic Osteosarcoma

Cancers that metastasize to the lungs represent a major challenge in both basic and clinical cancer research. Oncolytic viruses are newly emerging options but successful delivery and choice of appropriate therapeutic armings are two critical issues. Using an immunocompetent murine K7M2-luc lung metastases model, the efficacy of MYXV armed with murine LIGHT (TNFSF14/CD258) expressed under virus-specific early/late promoter was tested in an advanced later-stage disease K7M2-luc model. Results in this model show that mLIGHT-armed MYXV, delivered systemically using ex vivo pre-loaded PBMCs as carrier cells, reduced tumor burden and increased median survival time. In vitro, when comparing direct infection of K7M2-luc cancer cells with free MYXV vs. PBMC-loaded virus, vMyx-mLIGHT/PBMCs also demonstrated greater cytotoxic capacity against the K7M2 cancer cell targets. In vivo, systemically delivered vMyx-mLIGHT/PBMCs increased viral reporter transgene expression levels both in the periphery and in lung tumors compared to unarmed MYXV, in a tumor- and transgene-dependent fashion. We conclude that vMyx-mLIGHT, especially when delivered using PBMC carrier cells, represents a new potential therapeutic strategy for solid cancers that metastasize to the lung.

EnLIGHTenment of tumor vessel normalization and immunotherapy in glioblastoma

Glioblastoma multiforme (GBM) is a highly vascularized and aggressive brain tumor. Despite aggressive standard care, GBM remains predominantly fatal; hence, new innovative therapies are required. Recent research published in the Journal of Pathology has identified the CGKRK peptide as a promising tool with which to specifically target the tumor vasculature from high-grade glioma. This tumor vessel-homing peptide was fused to the tumor necrosis factor superfamily member LIGHT/TNFSF14, and injected intravenously into murine orthotopic GBM models. After treatment, the tumor vasculature appeared to be less abnormal, with normalized features such as increased endothelial barrier integrity, pericyte contractility, and tumor perfusion. Moreover, CGKRK-LIGHT induced the appearance of high endothelial venules (HEVs), which are specialized structures that play a role in lymphocyte trafficking and have been shown to increase T-cell infiltration in solid tumors. Combining CGKRK-LIGHT with anti-angiogenic and immune checkpoint blockade treatments boosted HEV induction and cytotoxic T-cell infiltration, leading to a reduction in tumor burden. In this Commentary, I highlight the therapeutic opportunities provided by and the current limitations of LIGHT-vascular targeting peptide as a new approach to target GBM and enhance tumor vessel delivery and immunotherapy efficacy. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The promise and challenges of immune agonist antibody development in cancer

Immune cell functions are regulated by co-inhibitory and co-stimulatory receptors. The first two generations of cancer immunotherapy agents consist primarily of antagonist antibodies that block negative immune checkpoints, such as programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte protein 4 (CTLA4). Looking ahead, there is substantial promise in targeting co-stimulatory receptors with agonist antibodies, and a growing number of these agents are making their way through various stages of development. This Review discusses the key considerations and potential pitfalls of immune agonist antibody design and development, their differentiating features from antagonist antibodies and the landscape of agonist antibodies in clinical development for cancer treatment.

Vessel Normalization in the Spot-LIGHT of Cancer Treatment

Targeting the aberrant, nonfunctional tumor vasculature is one of the most promising approaches of new anticancer therapies. Here, we discuss a recent publication and a novel mechanism by which tumor-associated macrophages can actively induce vessel normalization and junction stability, and improve the distribution of therapeutic drugs into a tumor.

A novel vaccine containing EphA2 epitope and LIGHT plasmid induces robust cellular immunity against glioma U251 cells

EphA2 is a receptor tyrosine kinase and can be acted as an attractive antigen for glioma vaccines. In addition, LIGHT plays an important role on enhancing T cell proliferation and cytokine production. To improve the CTL mediated immune response against glioma cells, we prepared the novel vaccine containing EphA2(883-891) peptide (TLADFDPRV) and LIGHT plasmid and utilized it to immunize the HLA-A2 transgenic HHD mice. In addition, trimera mice were immunized with the novel vaccine to elicit the antitumor immune response. The results demonstrated that the novel vaccine could induce robust cellular immunity against glioma U251 cells without lysing autologous lymphocytes. Moreover, the novel vaccine could significantly inhibit the tumor growth and prolong the life span of tumor bearing mice. These findings suggested that the novel vaccine containing EphA2 epitope and LIGHT plasmid could induce anti-tumor immunity against U251 cells expressing EphA2, and provided a promising strategy for glioma immunotherapy.

Creation of a lysine-deficient LIGHT mutant with the capacity for site-specific PEGylation and low affinity for a decoy receptor

The cytokine LIGHT is a promising candidate for cancer therapy. However, the therapeutic effect of LIGHT as a systemic anticancer agent is currently insufficient because of its instability and its binding to nonfunctional soluble decoy receptor 3 (DcR3), which is overexpressed in various tumors. Modification of proteins with polyethylene glycol (PEGylation) can improve their in vivo stability, but PEGylation may occur randomly at all lysine residues and the NH(2)-terminus; therefore, PEGylated proteins are generally heterogeneous and have decreased bioactivity. In this study, we attempted to create a lysine-deficient LIGHT mutant that could be PEGylated site-specifically and would have lower affinity for DcR3. We prepared phage libraries expressing LIGHT mutants in which all the lysine residues were replaced with other amino acids. A lysine-deficient LIGHT mutant [mLIGHT-Lys(-)] was isolated by panning against lymphotoxin beta receptor (LTbetaR). mLIGHT-Lys(-) could be site-specifically PEGylated at its NH(2)-terminus, yielding molecular uniformity and in vitro bioactivity equal to that of non-PEGylated, wild-type LIGHT. Furthermore, mLIGHT-Lys(-) was not trapped by the nonfunctional DcR3, despite binding to its functional receptors. These results suggest that mLIGHT-Lys(-) might be a useful candidate for cancer therapy.

Creation of a LIGHT mutant with the capacity to evade the decoy receptor for cancer therapy

The cytokine LIGHT activates various anti-tumor functions through its two receptors, lymphotoxin beta receptor (LTbetaR) and herpes virus entry mediator (HVEM), and is expected to be a promising candidate for cancer therapy. However, LIGHT is also trapped by decoy receptor 3 (DcR3), which is highly expressed in various tumors. Here, we used phage display technique to create LIGHT mutants that specifically bind LTbetaR and HVEM, and is not trapped by DcR3 for optimized cancer therapy. We constructed phage library displaying structural variants of LIGHT with randomized amino acid residues. After the affinity panning, we created 6 clones of LIGHT mutants as candidates for DcR3-evading LIGHT. Analysis of binding affinities showed that all candidates had 10-fold lower affinities for DcR3 than wild-type LIGHT, while 5 of the 6 clones had almost the same affinity for LTbetaR and HVEM. Furthermore, analysis of detailed binding kinetics showed that lower affinity for DcR3 is dependent on their faster off-rate. Further, we showed that the LIGHT mutant had almost the same cytotoxicity via LTbetaR, and had 62-fold higher DcR3-evading capacity compared to the wild type. Our data provide valuable information for construction of more functional LIGHT mutants that might be powerful tools for cancer therapy.