Appleton, Elizabeth

Abstract T-cell immune tolerance is established in part through the activity of the autoimmune regulator (AIRE) transcription factor in medullary thymic epithelial cells (mTEC) of the thymus. AIRE induces expression of peripheral tissue–specific self-antigens for presentation to naïve T cells to promote activation/deletion of autoreactive T cells. This traditional role of AIRE in mTECs is to prevent autoimmunity. Herein, we demonstrate that tumors mimic the role of AIRE in mTECs to evade immune rejection. We found that AIRE induced a profile of “selfness” at the RNA and protein levels which, when presented on major histocompatibility complexes (MHC), shielded the tumor from inherently self-tolerized T cells. Moreover, we describe an in vivo immunotherapy in which engineered changes in AIRE expression in tumor cells altered their profile of selfness, exposing both AIRE-modified and parental unmodified tumor cells to T-cell attack. Therefore, by resetting the immunologic selfness of cancer cells, this AIRE-mediated immunotherapy (i) converted a highly tolerized T-cell compartment into a tumor-reactive T-cell population; (ii) conferred upon nonimmunogenic tumors de novo sensitivity to immune checkpoint blockade; (iii) removed the need to identify potentially immunogenic tumor-associated antigens as targets for generation of T-cell responses; and (iv) lead to potent T cell–mediated rejection of aggressive, immunologically cold, nonimmunogenic tumors. Patient RNA sequencing data showed that the expression of AIRE predicted response to immune therapies with a strong correlation between AIRE expression and markers of T-cell receptor signaling, suggesting that our studies have therapeutic translational value.

Abstract Most oncolytic viruses are delivered by intratumoural injection, and local administration can induce regression of both injected and distant tumours in mice and patients. However, the mechanisms by which local viral infection reprograms systemic immunity remain poorly understood. Here we show that intratumoural RP1, an oncolytic HSV-1 encoding GM-CSF and GALV-GP-R ⁻ , drives regression of injected and uninjected murine melanoma tumours and prolongs survival. RP1 elicits coordinated CD4 ⁺ and CD8 ⁺ T cell infiltration accompanied by local cytokine remodelling, reshaping the immune landscape at both tumour sites. Leveraging the Timer of Cell Kinetics and Activity (Tocky) system and Kaede photoconvertible protein technology, we resolve the temporal dynamics of CD8 ⁺ T cell responses following local virotherapy and identify two systemically induced, virus-driven CD8 ⁺ T cell populations distinguished by TCR engagement kinetics: antigen-engaged Timer-positive ‘viral-induced precursors’ (VIPs) and Timer-negative KLRG1 ⁺ ‘viral-induced terminal effectors’ (VITEs). Single-cell transcriptomic and pseudotime analyses reveal divergent differentiation trajectories; VIPs exhibit sustained antigen engagement within the tumour microenvironment (TME), a transcriptional programme associated with self-renewal, and preferential homing to draining lymph nodes. A VIP-associated gene signature correlates with clinical response to RP1 plus PD-1 blockade in the IGNYTE trial of RP1 and nivolumab in PD-1-refractory melanoma and is independently associated with response to immune checkpoint inhibitor (ICI) therapy in melanoma. These findings establish a mechanistic link between local oncolytic virotherapy, systemic CD8 ⁺ T cell reprogramming, and durable regression of distant lesions in patients.

Background Antitumor immune responses induced by oncolytic immunotherapy (OI) are often followed by upregulation of programmed death-ligand 1 (PD-L1). As such, the combination of OI with blockade of the programmed cell death protein-1 (PD-1)/PD-L1 axis has demonstrated therapeutic activity in preclinical and clinical trials. The purpose of this study is to understand further the immune-mediated mechanism of interaction between oncolytic viruses and anti-PD-1 therapy. Methods Tumor cells and immune cells (splenocytes) were cultured separately, or in co-culture with vusolimogene oderparepvec, an oncolytic herpes simplex virus expressing the fusogenic gibbon-ape leukemia virus-fusogenic membrane glycoprotein protein (GALV) and granulocyte-macrophage colony-stimulating factor (GM-CSF), also known as RP1. Viral replication, interferon (IFN) responses and PD-L1 expression were analyzed using wild-type, IFNAR1, TNFAR1 and STING knockout splenocytes. In vivo studies evaluated immune cell infiltrates into the tumor following RP1 administration with anti-PD-1 therapy. Results RP1 replication was evident in tumor cells but not splenocytes. This was also accompanied by upregulated IFN expression in cultured splenocytes that was absent in cultured tumor cells. However, when these cell types were co-cultured, splenocytes mediated an interferon response to RP1 via STING that was transmitted to tumor cells in a non-touch-dependent manner. Tumor cells responded to these input signals via upregulation of cell surface major histocompatibility complex-I and PD-L1 through tumor intrinsic JAK-STAT signaling. In vivo, an IFN signature was observed following intratumoral injection of RP1, both in injected and non-injected tumors, which was further increased when combined with anti-PD-1 therapy. Marked upregulation of PD-L1 was observed in tumors injected with RP1 accompanied by the recruitment of CD11b+Ly6G+neutrophils into the tumor microenvironment, which stained positive for PD-L1. Conclusion Overall, the data demonstrate that RP1 remodels the tumor microenvironment through a combination of direct and indirect effects on both tumor and immune cells, resulting in an overall more inflamed phenotype.

Abstract Description We used C57BL/6 mice bearing B16-F10 tumors expressing EGFRviii, treated with anti-EGFRviii CAR T cells and the oncolytic virus vesicular stomatitis virus (VSV). TCR signaling in CAR T cells was investigated using the novel Tocky transgenic mouse model, which reports T cell activation over time using an unstable fluorescent protein reporter of Nr4a3. We further investigated CAR T phenotypes using CyTOF and scRNA-Seq. Using an MHC I tetramer for the dominant VSV epitope VSV-N52-59, we found that 20-50% of transfused CAR T adopted TCR specificity against VSV-N (TCR-primed), far above the predicted frequency in a naïve T cell repertoire. Ex vivo, these TCR-primed CAR T produced increased levels of Granzyme B and IFNγ over tetramer negative CAR T against either TCR or CAR targets. TCR-primed CAR had decreased levels of T cell activation as compared to non-TCR-primed CAR. CyTOF and scRNA-Seq analyses demonstrated a hyper-effector phenotype among TCR-primed CAR, with increased expression of T-bet, CD44, Granzyme B, IFNγ, and perforin. TCR sequencing revealed hyper-expansion of VSV N-specific CAR T cells and little overlap in clonotypes between CAR T co-treated with PBS versus VSV. Overall, CAR T cells that undergo endogenous anti-viral TCR priming and signaling appear to adopt a unique phenotype that promotes their cytotoxic function. These data suggest that engineering anti-viral TCRs into CAR T could be used to improve efficacy with OV boosting. Funding Sources Supported by NIH T32GM145408 and NIH R01CA269384. Topic Categories Vaccines and Immunotherapy (VAC)

Abstract Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of liquid tumors but faces many challenges against solid tumors including T cell exhaustion and poor CAR durability. Here, we show that engaging the CAR T cell endogenous TCR using an oncolytic virus (OV) enhances CAR T cell functionality, durability, and therapy. Upon combination therapy of solid tumors with CAR T cells and vesicular stomatitis virus (VSV), a subpopulation of antiviral, TCR-primed CAR T cells was generated with enhanced effector functions, altered activation states, and differential gene and protein expression when compared to CAR T cells that do not undergo TCR priming. Single cell RNA-sequencing showed clonal expansion of anti-VSV CAR T cells, selective avoidance of exhaustion, and enhancement of effector-associated genes with VSV-mediated CAR T cell expansion. CD4 T cells played a pivotal role in both the generation and polarization of these TCR-primed CAR T cells. These results provide a strong rationale both for a novel use of intravenous administration of oncolytic viruses with separate applications from their direct oncolytic activity and for directly exploiting the TCR and its endogenous interactions as tools for fine tuning the phenotype and function of CAR T cells, with particular efficacy against solid tumors.

Abstract T cell immune tolerance is established in part through the activity of the Auto-immune Regulator (AIRE) transcription factor in the medullary Thymic Epithelial Cells (mTEC) of the thymus. AIRE induces expression of SELF peripheral tissue-specific antigens for presentation to naïve T cells to promote activation/deletion of potentially autoreactive T cells. We show, for the first time to our knowledge, that tumors mimic the role of AIRE in mTEC to evade immune rejection. Thus, by expressing a broad range of SELF epitopes against which minimal functional T cell reactivities exist because of thymic deletion, AIRE acts as a master controller of SELFNESS, effectively cloaking the tumor from T cell attack. Moreover, we describe a completely novel immunotherapy in which engineered changes in AIRE expression in tumor cells alters their profile of SELFNESS, exposing both AIRE-modified, and parental unmodified, tumor cells to T cell attack. Consistent with our studies, patient RNAseq shows expression of AIRE predicts response to immune therapies with a strong correlation between AIRE expression and markers of TCR signaling. Therefore, by re-setting the immunological SELFNESS of cancer cells, this novel AIRE-mediated immunotherapy 1). converts a highly tolerized T cell compartment into a heteroclitic tumor-reactive T cell population; 2) confers de novo sensitivity to immune checkpoint blockade upon non-immunogenic tumors; 3). completely removes the need to identify potentially immunogenic tumor-associated antigens as targets for generation of de novo CD8+ and helper CD4+ T cell responses; and 4) leads to potent T cell-mediated rejection of aggressive, immunologically cold, non-immunogenic tumors.

Intravenous infusion of oncolytic reovirus in patients leads to infection of brain tumors, infiltration by cytotoxic T cells, and up-regulation of PD-L1.

Objective Oncolytic viruses (OVs) represent promising, proinflammatory cancer treatments. Here, we explored whether OV-induced innate immune responses could simultaneously inhibit HCV while suppressing hepatocellular carcinoma (HCC). Furthermore, we extended this exemplar to other models of virus-associated cancer. Design and results Clinical grade oncolytic orthoreovirus (Reo) elicited innate immune activation within primary human liver tissue in the absence of cytotoxicity and independently of viral genome replication. As well as achieving therapy in preclinical models of HCC through the activation of innate degranulating immune cells, Reo-induced cytokine responses efficiently suppressed HCV replication both in vitro and in vivo. Furthermore, Reo-induced innate responses were also effective against models of HBV-associated HCC, as well as an alternative endogenous model of Epstein–Barr virus-associated lymphoma. Interestingly, Reo appeared superior to the majority of OVs in its ability to elicit innate inflammatory responses from primary liver tissue. Conclusions We propose that Reo and other select proinflammatory OV may be used in the treatment of multiple cancers associated with oncogenic virus infections, simultaneously reducing both virus-associated oncogenic drive and tumour burden. In the case of HCV-associated HCC (HCV-HCC), Reo should be considered as an alternative agent to supplement and support current HCV-HCC therapies, particularly in those countries where access to new HCV antiviral treatments may be limited.