Poster Presentation 36th Lorne Cancer Conference 2024

Using intravital two-photon imaging to gain insights into T cell dynamics and the influence of the tumour microenvironment in mouse models of glioma. (#141)

Matthias Mulazzani 1 , Kylie Luong 1 , Valeria Arcucci 1 , Verena C Wimmer 1 , Melinda Iliopoulos 1 , Kathy A Watson 1 , Kelly Rogers 1 , Misty R Jenkins 1 2
  1. Walter and Eliza Hall Institute of Medical Research, Parkville, VICTORIA, Australia
  2. Biochemistry and Chemistry, La Trobe Institute of Molecular Science, Melbourne, VIC, Australia

Chimeric Antigen Receptor (CAR) T cell therapy involves re-engineering patient-derived T cells to redirect T cell cytotoxicity against tumour cells. Whilst CAR T cell therapy has demonstrated remarkable success in treating haematological malignancies, the same success has not yet been recapitulated in solid tumours, including brain tumours. To enhance CAR T therapy strategies, it is crucial to understand the dynamics of CAR T cells within the tumour microenvironment and their interactions with other cellular players.

We have established a chronic cranial window implant, which provides a window into the brain of immunocompetent mouse model of glioma (Mulazzani et al, 2019, PNAS). In combination with two-photon microscopy, this allows us to visualize tumour cell growth intravitally, longitudinally over the entire tumour course. We can examine the extent of T cell infiltration, accumulation, directionality, velocity, and persistence across time in the same mouse.

We found that antigen-specific CAR T cells can infiltrate and accumulate in the brain as early as two days after infusion, but the CAR T cells did not show migration towards or away from tumour; instead, they travelled along tumour border. Despite our in vitro T cell killing assays demonstrating CAR T cell effectiveness, they were unable to clear the tumour in vivo and the mice all eventually succumbed to disease. This suggests a possibility of other cellular players within the tumour microenvironment hindering T cells cytotoxicity, emphasising the need for combination therapy approaches.

This cutting-edge in vivo intravital imaging technique allows us to gain new insights into the complex interactions between CAR T cells and other immune cells and tumour cells within the brain microenvironment, which can ultimately inform the development of more effective immunotherapies for brain tumours.

  1. Mulazzani et al, 2019, Mulazzani et al, 2019, PNAS