E-Poster Presentation 34th Lorne Cancer Conference 2022

Establishing tumour organoid models of cancer of unknown primary enables in vitro testing of genomically informed and individualised drug treatments (#221)

Atara Posner 1 2 , Hui Li Wong 3 , Tharani Sivakumaran 3 , Jennii Luu 4 , Karla J Cowley 4 , Richard Rebello 1 2 , Krista Fisher 3 , Samantha Webb 3 , Penny Schofield 3 , Anna deFazio 5 6 , Owen Prall 3 , Sean Grimmond 1 2 , Oliver Hofmann 1 , Kaylene J Simpson 4 7 , Frederic Hollande 1 2 , Linda Mileshkin 3 , Richard Tothill 1 2
  1. University of Melbourne Centre for Cancer Research, The University of Melbourne, Melbourne, Melbourne, Victoria, Australia
  2. Department of Clinical Pathology, The University of Melbourne, Melbourne, Victoria, Australia
  3. Peter MacCallum Cancer Centre, Melbourne, Vic, Australia
  4. Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  5. The Westmead Institute for Medical Research, The University of Sydney, Sydney, NSW, Australia
  6. Department of Medical Oncology, Crown Princess Mary Cancer Centre, Westmead Hospital, Sydney, NSW, Australia
  7. Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia

Cancer of unknown primary (CUP) constitutes a poor outcome group of heterogenous metastatic cancers whereby a standardized clinical investigation fails to identify a tumour site of origin. In the absence of a known tissue of origin (TOO), clinical decision making is challenging, and treatments are limited and often ineffective.

There is currently a paucity of preclinical models of CUP tumours. We propose that establishing three-dimensional cell cultures (tumour organoids) for CUP may be useful to empirically test multiple drugs in vitro and then direct the most effective treatments in individual patients. Furthermore, this enables development of in vitro models of rare cancer types enriched in the CUP population for future discovery research.

As part of the Solving Unknown Primary Cancer (SUPER) program we successfully established tumour organoids in 35% (7/20) of cases. These were whole genome and transcriptome sequenced (WGTS) to confirm matching genomic profiles of the organoids and the originating tumour biopsies. The genomics data was used inform likely TOO as well as identify putative therapeutic targets.

Through the Victorian Centre for Functional Genomics (VCFG) we are currently conducting a compound screen on five CUP organoid cell lines to empirically test the sensitivity of CUP organoids to anti-cancer treatments. Fifty compounds per patient have been selected based on the standard of care site directed treatment (informed by the WGTS predicted TOO) or molecularly targeted treatments based on genomic alterations detected in individual tumours. Organoids were treated with compounds at multiple doses, imaged and quantified for structure size and extent of death.   

Although challenged by the inherent uncertainty of cancer type that would normally inform optimal growth conditions for organoid cell culture, and the limitations of collecting small amounts of fresh tumour samples from advanced metastatic patients, establishing organoids was feasible in approximately one third of CUP cases. These organoid models can be used for in vitro drug testing and may eventually be used for directing better treatment for CUPs.