Flash Talk and Poster Presentation 35th Lorne Cancer Conference 2023

Identifying novel vulnerabilities to sensitise Lkb1-mutant lung adenocarcinoma to T cell mediated killing   (#12)

Jackson A McDonald 1 2 , Danielle Boyd 1 , Sarah Diepstraten 2 3 , Stephen Wilcox 4 , Sarah MacRaild 4 , Lin Tai 3 , Andrew Kueh 3 , Marian Burr 5 6 7 8 9 , Sarah Best 2 10 , Marco Herold 2 3 , Kate Sutherland 1 2
  1. ACRF Cancer Biology and Stem Cells Division, WEHI, Melbourne, Victoria, Australia
  2. Department of Medical Biology, The University of Melbourne, Melbourne, Victoria, Australia
  3. Blood Cells and Blood Cancers Division, WEHI, Melbourne, Victoria, Australia
  5. Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
  6. Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
  7. Department of Haematology, Peter MacCallum Cancer Centre and The Royal Melbourne Hospital, Melbourne, VIC, Australia
  8. Division of Genome Science and Cancer, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
  9. Department of Anatomical Pathology, ACT Pathology, Canberra Health Services, Canberra, ACT, Australia
  10. Personalised Oncology Division, WEHI, Parkville, Victoria, Australia

KRAS is the most frequently altered oncogene in lung adenocarcinoma (LUAD). Recently, the clinical development of targeted therapies has improved the treatment of a subset of patients, however the heterogeneity of KRAS mutant LUAD remains a clinical challenge. Identifying tumour intrinsic dependencies through common co-occurring mutations are sought to more effectively target KRAS-mutant LUAD. Loss-of-function mutations found in STK11/Lkb1, are frequently found co-mutated with KRAS, and comprise an aggressive form of the disease, with resistance to chemotherapy. Immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 axis, which aims to unleash CD8 effector T cells against tumours, are currently used as a first-line treatment strategy for KRAS mutant LUAD patients. However, patients that have the co-mutation of KRAS and STK11 fail to respond to ICIs. Therefore, a greater understanding of the tumour-intrinsic processes that allow STK11/Lkb1 mutant tumours to evade immune detection is required for improving therapeutic outcomes.


Here, we have used an unbiased whole-genome CRISPR knockout screening approach in cancer cell lines generated from the KrasG12D/+/Lkb1fl/fl (KL) mouse model to unveil tumour-intrinsic mechanisms underlying anti-tumour immunity. To identify gene targets that sensitise tumour cells to T cell mediated killing, a co-culture method using the OVA/OT-I system was employed. Importantly, we identified genes in our screen that when deleted confer resistance to T cell mediated killing, which are involved in interferon signalling (Jak1, Stat1, Ifngr1) and MHC-I presentation (B2m, H2-k1), supporting our robustness of our screening platform. Excitingly, several genes were found to sensitise KL tumour cells to T cell mediated killing. Recent investigations validating the ability of candidate genes to sensitise KL tumour cells to T cell killing will be presented. Together, these results demonstrate the power of whole genome CRISPR screens in identifying candidate genes that may serve as therapeutic targets to improve treatment responses in KRAS/STK11/Lkb1 mutant LUAD patients.