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TRX1-enhanced CAR T cells retain their antitumor functions under pro-oxidative conditions

ABSTRACT: Immunotherapies with CAR-T cells achieve remarkable success, especially against B-cell malignancies. However, their activity against non-hematopoietic solid tumors is very limited. One central cause of this failure may be that a pro-oxidative tumor microenvironment can downmodulate the activation and migration of T-cells. In contrast to tumor cells, primary T cells have very low levels of antioxidants. This makes them prone to pro-oxidative effects. Oxidation-induced dysregulation of actin cytoskeletal dynamics hinders T-cell migration which allows only low tumor infiltration rates. In addition, the proliferation and the effector functions of T-cells (tumor cell killing) are disrupted. In order to strengthen human CAR-T cells against a pro-oxidative tumor microenvironment, we have increased increase their antioxidant capacity, e.g. by expressing antioxidants. We aimed to characterize the importance of antioxidant empowerment at functional level and at the molecular level. Among the antioxidant systems, thioredoxin1 (TRX1)-empowerment, allowed CAR T cells to retain their capacities for cytolytic immune synapse formation, cytokine release, proliferation, and cytotoxicity under pro-oxidative conditions. At the molecular level, gene expression analysis revealed that a pro-oxidative micromilieu caused a downmodulation of costimulatory and cytokine signals of T cells. One unique focus of this study was also to investigate global influence of reactive oxygen species on protein oxidation in T cells. Therefore, using TRX1 kinetic trapping and consequently mass spectrometry was employed to get insight into global oxidation levels in T cells. This analysis, namely redoxosome analysis, unveiled 196 oxidized proteins which were annotated to regulate several antitumor T cell functions. Taken together, our results provide evidence that TRX1 empowerment can increase CAR T cell efficacy against solid tumors.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Thomas Ruppert

LAB HEAD: Thomas Ruppert

PROVIDER: PXD031073 | Pride | 2022-11-23

REPOSITORIES: Pride

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Project description:Anti-cancer immunotherapy approaches are increasingly coveted. Chimeric antigen receptor (CAR)-T cell therapy has been shown to be an effective treatment for hematological tumors, but the treatment of solid tumors still lacks effectiveness, due to lower intra-tumor infiltration of CAR-T cells and tumor-induced immunosuppression. Macrophages represent a very large proportion of the tumor environment, participate in many aspects to tumor development and therefore represent interesting therapeutic targets. Macrophages can infiltrate solid tumor tissue and interact with almost all cellular components in the tumor microenvironment. In addition, macrophages can also promote a direct anti-tumor response by phagocyting tumor cells. We have developed macrophages expressing a CAR receptor against the HER2 antigen. The CAR receptor possesses an intracellular domain CD3ζ having homology with the protein FcεRI-γ, which once activated by the recognition antibody-antigen, induces the phagocytic activity of macrophages. 72% of macrophages express the CAR after transduction. CAR-M can specifically phagocyte HER2 coated-beads in a much more effective way than WT macrophages. We have then confirmed the capacity of CAR-M to phagocyte HER2+ cancer cell lines. Co-culture of CAR-M with breast cancer tumoroids (HER2+ or HER2-) has also been performed demonstrating their efficacy in a more complex environment. However, in the tumor microenvironment, due to their plasticity, macrophages tend to adopt an anti-inflammatory phenotype losing their anti-tumor activities. We have therefore developed a combined strategy by inhibiting two proprotein convertases, Furin and PC1/3 in CAR-M. The inhibition of furin or PC1/3 induces an increase in pro-inflammatory markers and maintains macrophage activation in the presence of cancer cells. In addition, HER2+ CAR-M with shFurin or shPC1/3 greatly increases the phagocytic activity on Her2+ beads or Her2+ tumors. These enzymes are therefore phenotypic regulators of macrophages. Our strategy is therefore based on a double activation of tumor-infiltrating macrophages. The first one consists in boosting the phagocytic activity of macrophages by having them express a CAR receptor targeting a tumor antigen. The second allows their reprogramming towards a pro- inflammatory phenotype by the inhibition of Furin and/or PC1/3 proprotein convertases

Project description:A significant challenge for chimeric antigen receptor (CAR) T cell therapy against glioblastoma (GBM) is its immunosuppressive tumor microenvironment (TME), which is densely populated and supported by protumoral glioma-associated microglia and macrophages (GAMs). Targeting CD47, a don't-eat-me signal overexpressed by tumor cells, disrupts the CD47-SIRPalpha axis and induces GAM phagocytic function. However, antibody-mediated CD47 blockade monotherapy is associated with toxicity and low bioavailability in solid tumors. To overcome these limitations, we combined local CAR T cell therapy with paracrine GAM modulation to effectively eliminate GBM. To this end, we engineered a new CAR T cell against epidermal growth factor receptor variant III (EGFRvIII) that constitutively secretes a signal regulatory protein gamma (SIRPgamma)-related protein (SGRP) with high affinity to CD47. Anti-EGFRvIII-SGRP CAR T cells eliminated EGFRvIII+ GBM in a dose-dependent manner in vitro and eradicated orthotopically xenografted EGFRvIII-mosaic GBM by locoregional application in vivo. This resulted in significant tumor-free long-term survival, followed by partial tumor control upon tumor re-challenge. Combining anti-CD47 antibodies with anti-EGFRvIII CAR T cells failed to achieve a similar therapeutic effect, underscoring the importance of sustained paracrine GAM modulation. Multidimensional brain immunofluorescence microscopy and in-depth spectral flow cytometry on GBM-xenografted brains showed that anti-EGFRvIII-SGRP CAR T cells accelerated GBM clearance, increased CD68+ cell trafficking to tumor scar sites and promoted GAM-mediated tumor cell uptake. In a peripheral lymphoma mouse xenograft model, anti-CD19-SGRP CAR T cells had superior efficacy to conventional anti-CD19 CAR T cells. Validation on human GBM explants revealed that anti-EGFRvIII-SGRP CAR T cells had a similar tumor-killing capacity to anti-EGFRvIII CAR monotherapy but showed a slight improvement in the maintenance of tumor-infiltrated CD14+ cells. Thus, local anti-EGFRvIII-SGRP CAR T cell therapy combines the potent antitumor effect of engineered T cells with the modulation of the surrounding innate immune TME. This results in the additive elimination of bystander EGFRvIII- tumor cells in a manner that overcomes the main mechanisms of CAR T cell therapy resistance, including tumor innate immune suppression and antigen escape.

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TRX1-enhanced CAR T cells retain their antitumor functions under pro-oxidative conditions

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