Solid Tumor Immunotherapy with T Cell Engager-Armed Oncolytic Viruses

AbstractMalignant mesothelioma (MM) is a treatment-resistant tumor originating in the mesothelial lining of the pleura or the abdominal cavity with very limited treatment options. More effective therapeutic approaches are urgently needed to improve the poor prognosis of MM patients. Chimeric Antigen Receptor (CAR) T cell therapy has emerged as a novel potential treatment for this incurable solid tumor. The tumor-associated antigen mesothelin (MSLN) is an attractive target for cell therapy in MM, as this antigen is expressed at high levels in the diseased pleura or peritoneum in the majority of MM patients and not (or very modestly) present in healthy tissues. Clinical trials using anti-MSLN CAR T cells in MM have shown that this potential therapeutic is relatively safe. However, efficacy remains modest, likely due to the MM tumor microenvironment (TME), which creates strong immunosuppressive conditions and thus reduces anti-MSLN CAR T cell tumor infiltration, efficacy and persistence. Various approaches to overcome these challenges are reviewed here. They include local (intratumoral) delivery of anti-MSLN CAR T cells, improved CAR design and co-stimulation, and measures to avoid T cell exhaustion. Combination therapies with checkpoint inhibitors as well as oncolytic viruses are also discussed. Preclinical studies have confirmed that increased efficacy of anti-MSLN CAR T cells is within reach and offer hope that this form of cellular immunotherapy may soon improve the prognosis of MM patients.

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Mechanisms that allow vaccination against an oncolytic vesicular stomatitis virus-encoded transgene to enhance safety without abrogating oncolysis

Scientific Reports ◽

10.1038/s41598-021-94483-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Amanda W. K. AuYeung ◽

Robert C. Mould ◽

Ashley A. Stegelmeier ◽

Jacob P. van Vloten ◽

Khalil Karimi ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Vesicular Stomatitis Virus ◽

Cell Response ◽

Viral Infections ◽

T Cell Response ◽

Oncolytic Viruses ◽

Oncolytic Virotherapy ◽

Cell Immunity ◽

Vesicular Stomatitis

AbstractVaccination can prevent viral infections via virus-specific T cells, among other mechanisms. A goal of oncolytic virotherapy is replication of oncolytic viruses (OVs) in tumors, so pre-existing T cell immunity against an OV-encoded transgene would seem counterproductive. We developed a treatment for melanomas by pre-vaccinating against an oncolytic vesicular stomatitis virus (VSV)-encoded tumor antigen. Surprisingly, when the VSV-vectored booster vaccine was administered at the peak of the primary effector T cell response, oncolysis was not abrogated. We sought to determine how oncolysis was retained during a robust T cell response against the VSV-encoded transgene product. A murine melanoma model was used to identify two mechanisms that enable this phenomenon. First, tumor-infiltrating T cells had reduced cytopathic potential due to immunosuppression. Second, virus-induced lymphopenia acutely removed virus-specific T cells from tumors. These mechanisms provide a window of opportunity for replication of oncolytic VSV and rationale for a paradigm change in oncolytic virotherapy, whereby immune responses could be intentionally induced against a VSV-encoded melanoma-associated antigen to improve safety without abrogating oncolysis.

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290 Cytokine and immune subset signatures in patients with various solid and hematological malignancies treated with oncolytic vaccinia virus delivered by autologous stromal vascular fraction cells

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0290 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A317-A317

Author(s):

Dobrin Draganov ◽

Antonio Santidrian ◽

Ivelina Minev ◽

Duong Nguyen ◽

Dmitriy Zamarin ◽

...

Keyword(s):

T Cell ◽

Vaccinia Virus ◽

Stromal Vascular Fraction ◽

Oncolytic Viruses ◽

Multiparameter Flow Cytometry ◽

Viral Dna ◽

Cell Responses ◽

The Impact ◽

Immune Subset

BackgroundThe development of oncolytic viruses for the treatment of cancer has been significantly hampered by their rapid clearance in circulation due to complement and antibody-mediated neutralization. In our recent first-in-human Phase I clinical trial, we evaluated the safety and feasibility of our approach to enhance virus delivery and improve tumor targeting by utilizing an autologous stromal vascular fraction (SVF) based cell delivery system. Patient sample analysis demonstrated that patients could be stratified based on the level of vaccinia virus amplification in vivo, as evidenced by analysis of persistent viral DNA in the blood.MethodsIn the current study, we evaluated the immunomodulatory potential of vaccinia virus delivered by autologous stromal vascular fraction (SVF)-derived cells and attempted to identify immunological correlates of successful vaccinia virus amplification in vivo. To this end, we performed an extensive time-course analysis of cytokines in patients‘ plasma as well as various peripheral blood immune subpopulations using Luminex multi-analyte profiling and multiparameter flow cytometry, respectively. We also analyzed the impact of this therapeutic approach on the innate and adaptive immune subpopulations, including NK cells, myeloid cells, as well as effector, regulatory and memory T cells.ResultsTherapy with SFV-delivered oncolytic vaccinia virus induced a coordinated activation of cytokine, T cell and NK cell responses in patients as early as 1 day after treatment, which peaked around 1-week and lasted for up to 1-month post treatment. The ability of the oncolytic virus to effectively amplify in cancer patients correlated with significant changes of multiple innate (NK) and adaptive (T cell) immunological parameters. Interestingly, patient stratification into groups with transient versus persistent viral DNA was linked to opposing and mutually exclusive patterns of robust activation of NK versus T cell responses, respectively. Our study also identified intriguing cytokine and immune subset frequency signatures present at baseline and associated with successful amplification and persistence of oncolytic vaccinia virus in vivo.ConclusionsOverall, this study establishes the timeline of treatment-related immunological changes and identifies biomarkers present at baseline and potential immunological correlates associated with the persistence of virus amplification in vivo. Therefore, our findings provide new insights into the role of interpatient immunological variability and will contribute to the proper evaluation of the therapeutic potency of oncolytic virotherapy in future clinical trials.

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