Abstract 1713P
Background
Appendiceal cancers (AC) are rare and frequently progress to peritoneal disease, with 5-year survival of 15% for adenocarcinomas (AA) and 75% for mucinous neoplasms (AMN). High-throughput single cell/nuclei RNA sequencing (sc/snRNAseq) can define the tumour microenvironment (TME) to understand disease progression and drug resistance. The study aim was to evaluate the biological profile and TME of AC peritoneal disease by sc/snRNAseq.
Methods
Fresh tumour tissue from 8 AC patients with peritoneal disease (3 AMN, 5 AA) were collected at cytoreductive surgery, Jul 2020-Apr 2022. Tissue was dissociated for scRNAseq or homogenised for nuclei extraction for snRNAseq. 3/4 single cell samples were pooled and 4 single nuclei samples were pooled before they were loaded onto the Chromium 10X platform where single cells/nuclei were captured by barcoded beads. RNA was reverse-transcribed into a library of amplified copy DNA which underwent next generation sequencing. Gene expression differences between different cell types were analysed to describe tumour and TME cell heterogeneity.
Results
A total of 24,492 single cells were sequenced. Cell populations identified by their typical or differential gene expression were: tumour (KRT20, EPCAM, MUC5AC, MUC2); immune (CD45) which included neutrophils (CXCL8, NCSF1), macrophages (CD68, CD14), T lymphocytes (CD3/4/8), Natural Killer Cells (NKG7, GLNY), B Lymphocytes (MS4A1); mesothelial (CALB2); and stromal (COL1A2, PDGFRA). An AA case had a tumour population suggestive of basal proliferating cells (MKI67, TOP2A, STMN1, PBK, CENPF, GTSE1) expressing neuroendocrine genes (CHGA/B, NPY), epithelial-mesenchymal-transition (EMT) genes (VIM, CDH2, MMP2) and neuronal genes (NEFL, NEFM, BEX1/2).
Conclusions
The gene expression profiles of individual cells in AC peritoneal disease suggest that un-/dedifferentiated tumour cells may be undergoing EMT and express markers of neuronal cells. Further validation will be performed with more cases and detailed cell type and state annotation linking to morphology and spatial organisation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Garvan Institute of Medical Research.
Funding
Royal Prince Alfred Cancer Services Grant; Christie Charitable Funds.
Disclosure
M.C. Strach: Financial Interests, Personal, Advisory Board: Specialised Therapeutics; Financial Interests, Personal and Institutional, Funding: ESMO; Financial Interests, Personal, Funding: RACP; Financial Interests, Institutional, Research Grant: Royal Prince Alfred Hospital. C. Koh: Financial Interests, Personal, Advisory Board: Takeda; Financial Interests, Personal, Invited Speaker: W.L. Gore. O. Aziz: Financial Interests, Institutional, Principal Investigator: CRUK. L.G. Horvath: Financial Interests, Personal, Advisory Board, Honorarium donated back to Chris O'Brien Lifehouse (My Hospital): Imagion Biosystems; Financial Interests, Personal, Invited Speaker, No payment: ANZUP (Australia and New Zealand Urogenital and Prostate) Clinical Trials Group; Financial Interests, Personal, Stocks/Shares, Stock options: Imagion Biosystems; Financial Interests, Personal, Stocks/Shares: My Emergency Doctor; Financial Interests, Institutional, Research Grant: Astellas; Financial Interests, Institutional, Invited Speaker, MK7684-001MK3475-991: MSD; Financial Interests, Institutional, Invited Speaker, AMG160 Phase IAMG509 Phase I: Amgen; Financial Interests, Institutional, Invited Speaker, 9785-CL-0335 (ARCHES): Astellas; Financial Interests, Institutional, Invited Speaker, SHR3680-002: Jiangsu Hengrui Medicines; Financial Interests, Institutional, Invited Speaker, C344102: Pfizer; Financial Interests, Institutional, Invited Speaker, JPCM: Eli Lilly; Financial Interests, Institutional, Invited Speaker, DASL-HiCAP: ANZUP; Financial Interests, Institutional, Invited Speaker, GALAHADACISPrevalence: Janssen-Cilag; Financial Interests, Institutional, Invited Speaker, GSK204697: GlaxoSmithKline; Financial Interests, Institutional, Invited Speaker, XL184-021: Exelexis; Financial Interests, Institutional, Invited Speaker, BGB-A317BGB-283BGB-A317-290: Beigene; Financial Interests, Institutional, Invited Speaker, FPT155-001: Five Prime; Financial Interests, Institutional, Invited Speaker, AB928CSP0003: ARCUS; Financial Interests, Institutional, Invited Speaker, Enzametenzarad: Anzup; Financial Interests, Institutional, Invited Speaker, ATG-017: Antagene. J. Barriuso: Financial Interests, Personal, Invited Speaker: Pfizer, Ipsen, NanoString, Servier; Financial Interests, Personal, Advisory Board: Nutricia; Financial Interests, Personal, Expert Testimony: AAA; Non-Financial Interests, Project Lead: EORTC; Non-Financial Interests, Invited Speaker: GETNE; Non-Financial Interests, Principal Investigator: Enets. All other authors have declared no conflicts of interest.