Shaping the Tumor Stroma and Sparking Immune Activation by CD40 and 4-1BB Signaling Induced by an Armed Oncolytic Virus

Abstract

Pancreatic cancer is a severe indication with short expected survival despite surgery and/or combination chemotherapeutics. Checkpoint blockade antibodies are approved for several cancer indications, but pancreatic cancer has remained refractory. However, there are clinical data suggesting that stimulation of the CD40 pathway may be of interest for these patients. Oncolytic viruses armed with immunostimulatory genes represent an interesting approach. Herein, we present LOAd703, a designed adenovirus armed with trimerized and that activates the CD40 and 4-1BB pathways, respectively. As many cells in the tumor stroma, including stellate cells and the infiltrating immune cells, express CD40 and some 4-1BB, we hypothesize that LOAd703 activates immunity and simultaneously modulates the biology of the tumor stroma. Tumor, stellate, endothelial, and immune cells were infected by LOAd703 and investigated by flow cytometry, proteomics, and functional analyses. LOAd703-infected pancreatic cell lines were killed by oncolysis, and the virus was more effective than standard-of-care gemcitabine. In xenograft models, LOAd703 efficiently reduced established tumors and could be combined with gemcitabine for additional effect. Infected stellate and tumor cells reduced factors that promote tumor growth (Spp-1, Gal-3, HGF, TGFβ and collagen type I), while chemokines were increased. Molecules involved in lymphocyte migration were upregulated on infected endothelial cells. Dendritic cells were robustly stimulated by LOAd703 to produce costimulators, cytokines and chemokines, and such DCs potently expanded both antigen-specific T cells and NK cells. LOAd703 is a potent immune activator that modulates the stroma to support antitumor responses. .

A Flow Cytometry-Based Method to Determine the Titer of Adenoviruses Expressing an Extraneous Gene

“…[22][23][24][25] In recent times, different types of recombinant oncolytic viruses have been developed, which enhance the functioning of the immune system against cancer, by attenuating the PD-1/PD-L1 axis and/or enhancing cancer immune system. [26][27][28] The high precision of expression titers like a GFP 50 titer helps accurate determination of the viral titer and transgene expression level, which, in turn, contributes to the quality control regimen for pharmaceutical products. Expression levels of transgene products can be measured by immunofluorescent staining using specific antibodies, instead of using reporter genes, including GFP.…”

Enhanced Antitumor Efficacy of Oncolytic Adenovirus–loaded Menstrual Blood–derived Mesenchymal Stem Cells in Combination with Peripheral Blood Mononuclear Cells

“…From here on, another important factor in improving the efficacy of CELYVIR should be the optimization of the OAdv used by, for example, using more potent OAdvs (44) or OAdvs encoding immunostimulatory sequences or transgenes to enhance the immune response against the tumor (24,45,46).…”

Transient redirection of T cells for adoptive cell therapy with telomerase-specific T helper cell receptors isolated from long term survivors after cancer vaccination

“…46,47 The natural role of these cells as "helpers" suggest that ACT with Th cells may be suitable for combination with other therapies, including checkpoint inhibitors, vaccines, oncolytic viruses or ACT with CTLs or CAR T cells. 5,6,48 The cloned TCRs, C13 and D71, are widely applicable, as they recognize a universal tumour antigen (hTERT) and are DP4restricted. These TCRs may thus be employed for exploring the Th approach across different cancers and combinatory regimes.…”