Virtual Flash Talk & E-Poster Presentation 34th Lorne Cancer Conference 2022

Characterisation of dual-specific chimeric antigen receptor T cells targeting Her2 and EGFRvIII to eliminate heterogeneous tumours (#34)

Hannah Hughes-Parry 1 2 , Melinda Iliopoulos 1 , Andrew J Kueh 1 , Marco J Herold 1 2 , Ryan S Cross 1 , Misty R Jenkins 1 2 3
  1. The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
  2. The Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
  3. Institute for Molecular Science, La Trobe University, Bundoora, VIC, Australia

The heterogeneity of solid tumours is a significant obstacle to the response and long-term remission of patient malignancies following Chimeric Antigen Receptor (CAR) T-cell immunotherapy in the clinic. While long-term remission has been achieved against haematological cancers, relapses have frequently occurred several months post-treatment due to outgrowing target antigen-negative tumour cells, and solid tumour responses have been less effective1. Therefore, to improve solid tumour elimination and prevent relapse, CAR T-cell immunotherapy may be improved by the targeting of multiple tumour-associated antigens through dual-specific CAR T-cells, in which T-cells are engineered to express CARs against multiple antigens. Existing studies have observed significant improvements over single-specific CAR T-cells2,3; however, few studies have interrogated the underlying biology. Therefore, we have characterised dual-targeting CAR T-cells against the Her2 and EGFRvIII tumour antigens in vitro and have generated an immunocompetent mouse model to test these constructs in vivo. Utilising functional in vitro assays to measure cytotoxic function, we have demonstrated that dual-specific CAR T- cells exhibit enhanced killing of heterogeneous target tumour cells compared to single-specific and pooled single-specific CAR T cells. Using CRISPR technology, we have also generated an immunocompetent mouse model tolerant to our antigens of interest, Her2 and EGFRvIII, and demonstrated the subcutaneous and intracranial growth of these antigen-expressing tumours. This model allows us to evaluate the efficacy of dual-targeting CAR T cells against heterogeneous tumours in a mouse model with an intact immune system.

  1. 1. O'Rourke, D.M.; Nasrallah, M.P.; Desai, A.; Melenhorst, J.J.; Mansfield, K.; Morrissette, J.J.D.; Martinez-Lage, M.; Brem, S.; Maloney, E.; Shen, A., et al. A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma. Sci Transl Med 2017, 9, doi:10.1126/scitranslmed.aaa0984.
  2. 2. Ruella M, Barrett DM, Kenderian SS, et al. Dual CD19 and CD123 targeting prevents antigen-loss relapses after CD19-directed immunotherapies. The Journal of Clinical Investigation 2016; 126: 3814-3826.
  3. 3. Hegde M, Corder A, Chow KKH, et al. Combinational Targeting Offsets Antigen Escape and Enhances Effector Functions of Adoptively Transferred T Cells in Glioblastoma. Molecular Therapy 2013; 21: 2087-2101.