Poster Presentation Melbourne Immunotherapy Network Winter Symposium 2021

Novel EGFRvIII-specific murine CAR T cells completely eliminate glioblastoma tumours (#100)

Rebecca C Abbott 1 2 , Daniel J Verdon 1 , Fiona M Gracey 3 , Hannah E Hughes-Parry 1 2 , Melinda Iliopoulos 1 , Katherine A Watson 1 , Matthias Mulazzani 1 , Kylie Luong 1 , Colleen D'Arcy 4 , Lucy C Sullivan 5 , Ben R Kiefel 3 , Ryan S Cross 1 , Misty R Jenkins 1 2 6
  1. Department of Immunology, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
  2. Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
  3. Myrio Therapeutics, Scoresby, Victoria, Australia
  4. Anatomical Pathology, Royal Children's Hospital, Parkville, Victoria, Australia
  5. Department of Microbiology and Immunology, Peter Doherty Institute, Parkville, Victoria, Australia
  6. Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia

Glioblastoma is an aggressive and highly malignant brain tumour which accounts for approximately 60% of all adult brain cancer diagnosis and has a survival rate of just 5% over 5 years1. New and targeted treatments for glioblastoma are critically required to enhance patient survival. Chimeric Antigen Receptor (CAR) T cell therapy is a form of immunotherapy which is greatly enhancing the survival of patients with haematological malignancies2. This therapy provides a patient’s own immune cells with a synthetic receptor, enabling recognition and lysis of malignant cells. Thus far, all CARs have been developed by rederiving pre-existing monoclonal antibodies. Here, we have developed a novel pipeline using a human Retained Display (ReD) antibody platform to screen for single chain binders (scFvs) to EGFRvIII. We identified a high affinity binder; which we have designated GCT02 and used it to design a second generation CAR. We characterised the function of this CAR in vitro and in vivo orthotopic xenograft models of glioblastoma. Our GCT02 CAR generally secreted lower quantities of evaluated cytokines (with the exception of higher GCT02 CD8+ secretion of IFN-γ), with comparable cytotoxic function to the Clone 2173 (C2173) CAR; an EGFRvIII-specific CAR being currently used in clinical trials3, with a reported 300-fold lower affinity4. In our in vivo models, a single intravenously delivered dose of GCT02 CAR T cells completely eliminated implanted glioblastoma tumour cells two weeks post treatment. We have identified and characterised a high affinity EGFRvIII-specific CAR using a novel human phage display screening platform. The GCT02 CAR was found to have effective anti-tumour functions in vitro, and against in vivo xenograft models of glioblastoma.

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  3. O'Rourke DM, Nasrallah MP, Desai A, Melenhorst JJ, Mansfield K, Morrissette JJD, Martinez-Lage M, Brem S, Maloney E, Shen A et al. (2017) A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma. Science translational medicine. 9(399).
  4. Johnson LA, Scholler J, Ohkuri T, Kosaka A, Patel PR, McGettigan SE, Nace AK, Dentchev T, Thekkat P, Loew A et al. (2015) Rational development and characterization of humanized anti-EGFR variant III chimeric antigen receptor T cells for glioblastoma. Sci Transl Med. 7(275):275ra222.