Immune Response Is an Important Aspect of the Antitumor Effect Produced by a CD40L-Encoding Oncolytic Adenovirus

Abstract

Oncolytic adenovirus is an attractive platform for immunotherapy because virus replication is highly immunogenic and not subject to tolerance. Although oncolysis releases tumor epitopes and provides costimulatory danger signals, arming the virus with immunostimulatory molecules can further improve efficacy. CD40 ligand (CD40L, CD154) induces apoptosis of tumor cells and triggers several immune mechanisms, including a Thelper type 1 (T H 1) response, which leads to activation of cytotoxic T cells and reduction of immunosuppression. In this study, we constructed a novel oncolytic adenovirus, Ad5/3-hTERT-E1A-hCD40L, which features a chimeric Ad5/3 capsid for enhanced tumor transduction, a human telomerase reverse transcriptase (hTERT) promoter for tumor selectivity, and human CD40L for increased efficacy. Ad5/3-hTERT-E1A-hCD40L significantly inhibited tumor growth in vivo via oncolytic and apoptotic effects, and (Ad5/3-hTERT-E1A-hCD40L)-mediated oncolysis resulted in enhanced calreticulin exposure and HMGB1 and ATP release, which were suggestive of immunogenicity. In two syngeneic mouse models, murine CD40L induced recruitment and activation of antigenpresenting cells, leading to increased interleukin-12 production in splenocytes. This effect was associated with induction of the T H 1 cytokines IFN-g, RANTES, and TNF-a. Tumors treated with Ad5/3-CMV-mCD40L also displayed an enhanced presence of macrophages and cytotoxic CD8 þ T cells but not B cells. Together, our findings show that adenoviruses coding for CD40L mediate multiple antitumor effects including oncolysis, apoptosis, induction of T-cell responses, and upregulation of T H 1 cytokines. Cancer Res; 72(9); 2327-38. Ó2012 AACR.

Multimodal immunogenic cancer cell death as a consequence of anticancer cytotoxic treatments

“…However, the observation that the tumor microenvironment tends to be pro-oxidative 63 implies that a therapeutic approach using antioxidants to decrease ROS production would be favorable to stimulate antitumor immunity. Importantly, many anticancer agents, including chemotherapy, 30 radiation, 22 or oncolytic viruses, 9,64,65 have been shown to induce HMGB1 release from cancer cells, highlighting the significance of further addressing the mechanism of how these modalities affect the redox status of HMGB1.…”

“…70 We and others recently showed that oncolytic viruses induce secretion of extracellular ATP from human cancer cells (Figure 1). 9,65 Unlike ecto-CRT induction, the release of ATP and HMGB1 is triggered by a range of death-inducing stimuli, and is not restricted to induction in apoptotic cell death. 47 Although ATP production is required for efficient vaccinia virus production 71 and facilitates HIV infection through its interaction with P2Y2 receptors, 72 there is little knowledge of how oncolytic viruses provoke ATP release.…”

“…113 Recent studies delineated that oncolytic viruses such as vaccinia, measles, HSV-2, and adenovirus cause the release of HMGB1. 64,65,114,115,116,117 Although HMGB1 interacts with viral components and may modulate viral replication, 117 the molecular mechanisms of how each oncolytic virus differentially produces these DAMPs remain largely elusive.…”

“…However, there are only two reports showing that virus-induced ecto-CRT was correlated with enhanced intratumoral infiltrations of immune subpopulations, which accounted for the 'in vivo' remarkable antitumor immunity. 9,65 Several studies showed that recombinant oncolytic adenoviruses induced ACD in human malignant glioma cells, 120 brain tumor stem cells, 121 osteosarcoma cells, 105 and lung cancer cells. 122 Newcastle disease virus also triggered autophagy in glioma cells to promote its viral replication.…”

Intravenously usable fully serotype 3 oncolytic adenovirus coding for CD40L as an enabler of dendritic cell therapy

“…Unfortunately, adenovirus alone is not potent enough to initiate a powerful vaccine effect thus presenting the rationale for arming them with immunostimulatory molecules such as CD40L, a potent stimulator of dendritic cells (DCs). [4][5][6][7] There are more than 50 identified serotypes of adenoviruses. Serotype 5 adenoviruses (Ad5) are commonly used in gene therapy applications.…”