Poster Presentation 29th Lorne Cancer Conference 2017

Exploring the immunological landscape in locally advanced rectal cancer to improve neoadjuvant chemoradiotherapy followed by radical surgery (#188)

Joseph CH Kong 1 2 3 , Glen R Guerra 1 2 3 , Rosemary M Millen 2 3 , Satish K Warrier 1 , Craig Lynch 1 , Alexander G Heriot 1 , Paul Neeson 3 4 , Wayne A Phillips 3 5 , Robert G Ramsay 2 3
  1. Department of Surgical Oncology, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
  2. Differentiation and Transcription Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
  3. University of Melbourne, Melbourne, VIC, Australia
  4. Haematology Immunology Translational Research Laboratoy, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
  5. Surgical Oncology Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia

Subheadings: Developing immunoassays to optimize immunotherapy for patients with locally advanced rectal cancer.

Background: Current treatment algorithms for locally advanced rectal cancer indicate the use of neoadjuvant chemoradiotherapy followed by radical surgery. However, 20-30% will not respond to chemoradiotherapy at which point there are no other therapeutic options available. Recently it was confirmed that the immune status of patients with rectal cancer predicts disease progression (1). This finding suggests that approaches to increase the immune response in the patients with a suboptimal immune profile might improve patient outcomes. Accordingly, promising emerging immunotherapies employing cancer vaccination will commence next year involving our lab. In view of this, we have focused on developing assays that allow the real-time evaluation of immune responses in patients with solid tumours undergoing immunotherapies.

Methods: Fresh rectal cancer biopsies were processed to generate rectal cancer organoids and tumour-derived T infiltrating lymphocytes (TILs). TILs were FACS profiled to determine the proportion of cytotoxic and other T-cells. These are then co-cultured for seven days and organoid death was measured by fluorescence microscopy using an apoptotic marker Caspase 3/7 and propidium iodine.

Results: Thus far eight patients have been recruited for this pilot study. An effector (TILs) to target (organoid) ratio of 10:1 showed complete organoid death within 12 hours, whereas a ratio of 1:1 can take up to 24 hours or longer. Overall FACS analyses of the composition of the TIL population revealed more CD8+ and NKT cells than CD4+ and NK cells. Activation markers and proportion of T-regulatory cells were also assessed. Collectively a comprehensive picture of the phenotype and functionality of the rectal cancer-derived TILs has been generated.

Conclusion: As a proof of concept, we have established the first assays to our knowledge that test the ability of matched patient-derived TILs to kill rectal cancer cells from the same patient. These assays form a platform for the evaluation of immunotherapies on a patient specific basis.