Poster Presentation 31st Lorne Cancer Conference 2019

Colorectal cancer patient-derived xenografts for pre-clinical drug trials (#112)

Suad Abdirahman 1 2 , Adele Preaudet 2 , Lotta Burstroem 2 , Oliver Sieber 1 2 , Tracy Putoczki 1 2
  1. Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
  2. Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia

Colorectal cancer (CRC) is the third most common cancer worldwide, and is one of the most commonly occurring cancers in Australia. When detected early, CRC is treatable; however, patients often relapse and ultimately succumb to metastatic (m) disease. Despite many advances in cytotoxic and targeted therapies, chemotherapy response rates for mCRC remain low, primarily due to the development of treatment resistance. Our aim was to establish and characterise a cohort of CRC patient-derived xenografts (PDXs), a renewable resource that more accurately models the human disease, for use in pre-clinical therapeutic studies. Human tumour tissue was subcutaneously engrafted into immunocompromised mice directly after patient surgery. Tumours have been serially transplanted, with each passage biobanked and available for pre-clinical studies. Haematoxylin and Eosin staining, immunohistochemical staining, western blotting and genomic profiling have been used to compare the expression signatures of the transplanted tumours with the original patient tumour. We engrafted 33 patient tumours, with an overall engraftment success rate of 66.7%. However, we noted that 12.1% of these immediately turned into lymphomas, and a further 12.1% resulting in a mixed lineage whereby the PDX line resulted in both lymphomas and CRC tumours. These PDX lines have been excluded from our studies, resulting in an actual engraftment success rate of an overall 55% of PDXs that maintained the histopathological features of the original patient tumour. Ultimately, we had 16 PDXs composed of 3 Stage 1, 8 Stage 2, and 5 Stage 3 tumours. An additional 28 patient tumours have been archived for future use. For 4 of our PDX lines, second generation lines with acquired 5-Fluorouracil (5-FU) resistance, or Cetuximab resistance, are being generated. These new tools will allow us to investigate potential new therapeutics that can overcome resistance to these commonly used standard-of-care treatments. Our established CRC PDX library will serve as a platform that will facilitate the pre-clinical characterisation of novel therapies, and treatment combinations.