Late-breaking Poster Asia-Pacific Vaccine and Immunotherapy Congress 2024

Enhancing CAR T cells against solid tumours with novel gene-editing approaches (#109)

Thomas J Cole 1 , Phillip K Darcy 1 , Paul A Beavis 1 , Kevin Sek 1
  1. Peter MacCallum Cancer Centre, Melbourne

CAR T cell therapy has been incredibly successful in treating haematological malignancies but has faced additional hurdles in the context of solid tumours. One such challenge is immunosuppression by secreted metabolites such as adenosine at the tumour site. We have demonstrated that CRISPR deletion of the A2A adenosine receptor could armour CAR T cells against the TME leading to greater therapeutic efficacies in solid tumours. Alternatively, engineering CAR T cells to express the adenosine A1 receptor (A1R) at the tumour site energises CAR T cells by driving enhanced cytokine production and T cell effector differentiation. Utilizing CRISPR homology-directed repair, we were able to achieve expression of the A1R in CAR T cells following antigen stimulation at the tumour site only. This has been demonstrated in multiple CAR T cell models that tumour-specific A1R expression enhances CAR T cell effector function and tumour control in vivo. Weighted gene co-expression network analysis (WGCNA), ATAC-seq and scRNA-seq point towards the role of several transcription factors involved downstream in A1R CAR T cell signalling. Specifically, we identified IRF8 as a key mediator of effector differentiation and cytokine production. Given that the effector phenotype of A1R CAR T cells increases cytokine production, there is scope to test this gene-editing strategy in syngeneic immunocompetent mouse models with an intact immune system. Furthermore, this approach has the potential to synergise with checkpoint blockade as prolonged A1R signalling also drives exhaustion and upregulation of checkpoint receptors in CAR T cells. Leveraging the tumour-site specific expression of A1R, we can combine this approach with other strategies that promote memory and stem-like characteristics in CAR T cells leading to greater expansion and optimal CAR T cell differentiation upon antigen encounter.