Oral Presentation 32nd Lorne Cancer 2020

Novel ovarian cancer treatment using CAR-T cells targeting the non-functional P2X7 receptor (#25)

Carmela Ricciardelli 1 , Hayley Chapman 1 , Vasiliki J Willett 1 , Victoria N Nikitaras 1 , Anne M Macpherson 1 , Noor Alia A Lokman 1 , Veronika Bandara 2 , Batjargal Gundsambuu 2 , Tim Sadlon 2 , Silvana Napoli 2 , Simon C Barry 2 , Martin K Oehler 1 3
  1. Discipline of Obstetrics and Gynaecology, Adelaide Medical School, Robinson Research Institute, University of Adelaide, Adelaide, SA, Australia
  2. Molecular Immunology, Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
  3. Department of Gynaecological Oncology, Royal Adelaide Hospital, Adelaide, South Australia, Australia

P2X7 receptor (P2X7) is a ligand-gated ion channel which is activated in the presence of ATP, allowing calcium ions (Ca2+) to enter the cell through the opening of a pore. Prolonged exposure to ATP leads to conformational change in P2X7, leading to the formation of a non-functional form, nfP2X7. Recent studies have identified nfP2X7 on various cancer cells including ovarian cancer, but not healthy cells, which makes it a promising tumour associated antigen candidate for CAR T-cell immunotherapies.

In this study we assessed the effects of nfP2X7 CAR-T on ovarian cancer cell lines (SKOV-3 and OVCAR-3), normal peritoneal cells (LP-9) and primary serous ovarian cancer cells in vitro by MTT assay. We evaluated the effects of nfP2X7 CAR-T using a patient derived explant assay.  In addition, we investigated the effect of nfP2X7 CD3 CAR-T-cells in vivo using an OVCAR-3 xenograft model. OVCAR-3-Luc cells were injected intra-peritoneally (i.p,) into NOD/SCID (NSG) mice and mice with detectable tumours were randomised after 21 days to receive an i.p. injection of either nfP2X7 CAR T cells or un-transduced (UT) T cells..

nfP2X7 CAR-T significantly inhibited the survival of OVCAR-3 and primary serous ovarian cancer derived from patient ascites compared to UT T cells. No significant effects of  nfP2X7 CAR-T were observed on SKOV3 or LP-9 cells. nfP2X7 CAR T-cells induced significantly more apoptosis (measured by cleaved caspase 3 immunohistochemistry) compared to an equal number of UT T cells using a patient derived explant assay. Treatment with nfP2X7 CAR-T cells significantly reduced tumour burden in mice injected with OVCAR-3 cells compared to UT T cells after 2, 4 and 6 weeks of treatment.  In conclusion, this study demonstrates that nfP2X7 CAR-T-cells have great potential to be developed as novel immunotherapy for ovarian cancer.