Liseth, Olivia

Abstract The paradigm in the field of oncolytic virotherapy proposes that tumor cell killing by an oncolytic virus (OV) culminates in the priming of antitumor CD8+ T cells. However, this ignores the impact a highly immunodominant antiviral response against the OV has on the subdominant antitumor response, particularly with regard to the naturally low affinity of tumor antigens to their cognate T-cell receptors. To investigate this experimentally, we first studied the interaction between the two responses in B16 and MC38 tumor models, both expressing ovalbumin (OVA). Contrary to the accepted paradigm, the inflammatory vesicular stomatitis virus (VSV) failed to expand OVA-specific T cells in vivo unless armed with tumor-associated antigen (TAA). In fact, treatment with the control VSV led to the ablation of antitumor T cells and a shift toward dysfunction as determined by the upregulation of markers, including LAG3 and CD39, correlating with lower rates of survival. Combination with anti–PD-1 immune checkpoint blockade therapy significantly improved survival only when VSV expressed TAA. VSV-expressing altered peptide ligand variants of tumor antigens, which evade mechanisms of central tolerance, expanded near self-antigen–specific T cells with the ability to cross-react with tolerized tumor antigens, thus providing an antitumor effector population capable of proliferating in the presence of a potent antiviral response. Taken together, these findings offer a rational approach to OV design which preserves acute antitumor therapy provided by antiviral innate and T-cell responses while promoting the induction of tumor-specific T cells. Significance: Oncolytic viruses can induce an antiviral T-cell response that occludes an antitumor response, challenging the paradigm in the field and elucidating strategies to optimize the efficacy of oncolytic viroimmunotherapy.

Abstract Introduction We have shown that combining CAR T cells with oncolytic viruses (OVs) generates a subpopulation of highly cytotoxic CAR T cells that can mediate long-term solid tumor therapy. Methods To profile these CAR T cells, we used C57BL/6 mice bearing B16F10 tumors expressing EGFRviii, treated with anti-EGFRviii CAR T cells and the OV 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. Results 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 (referred to as TCR-primed), indicating significant in vivo expansion. 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. However, TCR-primed CAR T cells were notably less activated via Nr4a3 as compared to non-TCR-primed CAR T. CyTOF and scRNA-Seq analyses demonstrated a hypereffector phenotype among TCR-primed CAR, with increased expression of T-bet, CD44, granzyme B, IFNγ, and perforin. TCR sequencing revealed hyperexpansion of VSV N-specific CAR T cells and little overlap in clonotypes between CAR T co-treated with PBS versus VSV. These TCR-primed CAR T cells exhibited a CD4-helped phenotype with increased expression of chemotactic and migratory transcripts. When CAR T and OV were administered with antibody-mediated CD4 depletion, the TCR-primed CAR population was significantly diminished, emphasizing the importance of the immune triad for CAR T expansion. Conclusion Overall, CAR T cells that undergo endogenous anti-viral TCR priming and signaling adopt a unique phenotype that promotes their expansion and cytotoxic function. Interactions with CD4 T cells appear to be integral for the generation of this subpopulation of CD8 CAR T cells. Funding Source NIH Topic Categories Tumor Immunology: Checkpoints, Prevention, and Treatment (TIPT)

Chimeric antigen receptor (CAR) T cell therapy faces many challenges against solid tumors including T cell exhaustion and poor CAR durability. Here, we show that engaging the CAR T cell endogenous T cell receptor (TCR) using an oncolytic virus 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 non–TCR-primed CAR T cells. Single-cell RNA sequencing showed clonal expansion of anti-VSV CAR T cells and enhancement of effector-associated genes with VSV-mediated CAR T cell expansion. CD4 T cells played a pivotal role in the development of these TCR-primed CAR T cells. These results provide a strong rationale both for a novel use of systemic oncolytic virotherapy and for directly exploiting the CAR T cell TCR to fine tune the CAR T cell phenotype and function.

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.

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 The paradigm in the field of oncolytic virotherapy proposes that tumor cell killing by an oncolytic virus (OV) culminates in the priming of antitumor CD8 T cells. However, this ignores the impact a highly immunodominant antiviral response against the OV has on the antitumor response which has been weakened by mechanisms of central tolerance. Here, we show that inflammatory Vesicular Stomatitis Virus (VSV) failed to prime an adoptively transferred, or pre-existing, population of tumor-reactive T cells.Combination with αPD1 immune checkpoint blockade therapy improved survival only when VSV expressed tumor associated antigens (TAA). These data show that, in this model, the highly inflammatory OV VSV alone actively outcompetes antitumor immunity. However, we also show that viral expression of a mutant near-self TAA can break central tolerance expanding heteroclitic self-reactive and near-self-reactive T cells, thus overcoming viral immunodominance by promoting tumor-specific T cell proliferation in parallel with expanding antiviral T cells.

INTRODUCTION: Perinatal mental illness imparts a significant health burden. A multitude of factors are hypothesized to increase the incidence of perinatal mood and anxiety disorders (PMADs) in the fetal surgical population, including uncertain fetal prognosis and the inherent risks of surgery and preterm delivery. We sought to determine the disease course of PMADs in the fetal surgery population. METHODS: A retrospective chart review was conducted of fetal surgery patients from 2017 to 2021 at a tertiary care center. Demographics, surgical, obstetric, and psychiatric diagnoses were recorded. Standard descriptive analyses were performed. RESULTS: One hundred nineteen eligible patients were identified. Fetal surgery was performed at a median gestational age of 23.0 (range 16.0–34.0) weeks. Laser ablation of placental anastomoses (n=51) and in utero myelomeningocele repair (n=22) were the most common procedures. 26.8% (32/119) had preexisting mood disorders, with 59.3% (19/32) and 53.1% (17/32) on a baseline medication for depression or anxiety, respectively, prior to surgery. 26.4% (23/87) of patients without a history of anxiety or depression had a new diagnosis of PMAD. Two patients experienced suicidal ideation. 6.7% (8/119) and 10.1% (12/119) initiated a new psychiatric medication during or post-pregnancy, respectively. 19.8% (21/113) received a therapy referral. Among patients with baseline anxiety or depression, 62.5% (20/32) experienced an exacerbation postpartum with 25.0% (8/32) referred for therapy, and 34.3% (11/32) changing dose or medication for anxiety and 37.5% (12/32) for depression. CONCLUSION: Among patients undergoing fetal surgery, a high incidence of PMAD was identified. Most patients with prepregnancy anxiety or depression experienced an exacerbation postpartum. Further research into effective supportive interventions is warranted.