Poster Presentation 31st Lorne Cancer Conference 2019

Novel Peptide-MHC Chimeric Antigen Receptor T cells for the treatment of Diffuse Midline Glioma (#403)

Shiqi Wang 1 2 , Fiona Gracey 3 , Bradley McColl 3 , Ryan S Cross 1 , Misty R Jenkins 1 4
  1. Walter and Eliza Hall Institute of Medical Research, Victoria, AUSTRALIA, Australia
  2. My Room Clinical Research Fellow; Murdoch Children's Research Institute and Children's Cancer Foundation, Parkville, Victoria
  3. AffinityBIO, Small Technologies Cluster, Scoresby, Victoria
  4. Institute for Molecular Science, La Trobe University, Bundoora, Victoria, Australia

Diffuse Midline Glioma (otherwise known as DMG or DIPG, Diffuse Intrinsic Pontine Glioma) is a rare but devastating brain tumour of childhood: median age of diagnosis is 5 – 9 years of age, with 2 year overall survival of <10%.1 The only proven treatment is palliative radiotherapy that extends survival but does not provide cure.1 Recurrent mutations in Histone 3.3, resulting in a replacement of lysine by methionine at position 27 (K27M), are one of the most common, key driver mutations in DMG tumourigenesis.2 Patients who are HLA-A2 positive present a novel peptide at the cell surface derived from this K27M mutation;3 this HLA-A2 restricted H3K27M epitope has been the target of immune vaccine and T cell receptor-based approaches.4, 5

Chimeric Antigen Receptor(CAR)-T cell therapy is a promising form of adoptive cell therapy, that re-engineers patient-derived T cells to express a hybrid receptor specific to a tumour-specific antigen of choice.6 CAR-T therapy directed against the CD-19 antigen has been extraordinarily successful in various haematological malignancies,7 and its tumour-specific nature makes this therapy very appealing to apply to DMG.

We generated single chain variable fragments (scFv) against the novel H3K27M- HLA-A2 peptide-MHC complex by Retained Display screening;8 Clone 1 and Clone 2. These were cloned into a second generation CAR construct, and demonstrated cytotoxic function against H3K27M-HLA-A2 positive T2 cells in vitro, as well as corresponding cytokine release data.

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  8. 8. Beasley MD, Niven KP, Winnall WR, Kiefel BR. (2015) Bacterial cytoplasmic display platform Retained Display (ReD) identifies stable human germline antibody frameworks. Biotechnol J. 10(5):783-789.