ESTRO 2023 - Abstract Book

S693

Monday 15 May 2023

ESTRO 2023

Conclusion The single characteristic genus or the B/F ratio could not effectively predict RE or SARE. However, the enterotype classification could be the predictor of RE and SARE. PD-0824 Development of a hypoxia gene signature in locally advanced cervical cancer patients (NCT05029258) A. Datta 1,2 , M. Reardon 1 , S. Desai 3 , P. Hyder 3 , L. Barraclough 4 , K. Haslett 4 , J. O'Connor 1,2,5 , C. West 1 , A. Choudhury 1,4 , P. Hoskin 1,4,6 1 The University of Manchester, Division of Cancer Sciences, Shool of Medicine, Faculty of Biology Medicine and Health, Manchester, United Kingdom; 2 The Christie NHS Foundation Trust, Clinical Radiology, Manchester, United Kingdom; 3 The Christie NHS Foundation Trust, Clinical Histopathology, Manchester, United Kingdom; 4 The Christie NHS Foundation Trust, Clinical Oncology, Manchester, United Kingdom; 5 Institute of Cancer Research, Division of Radiotherapy and Imaging, London, United Kingdom; 6 Mount Vernon Cancer Centre, Clinical Oncology, Northwood, United Kingdom Purpose or Objective Cervical cancer is the fourth most frequent cancer in women for incidence and mortality. Hypoxia is a well-known negative prognostic factor and radioresistant component of solid tumours that can be assessed using gene expression signatures. We aimed to derive and validate a cervical cancer–specific gene signature. Materials and Methods Five cervical cancer cell lines(CaSki, HeLa, SiHa, SW-756, MS-751) were exposed to normoxia(21% O2) and hypoxia(1% O2) for 24h. Three independent experiments were carried out. RNA was extracted and RNA-sequencing performed on the Illumina Hi-Seq platform. Differentially expressed genes(DEGs) were used to derive a group of candidate genes. The Cancer Genome Atlas(TCGA) data for locally advanced cervical cancers(LACC; stage 1B2 to IVA) were used to train(n=71) the candidate genes using Prediction Analysis of Microarrays(PAM; 10-fold cross-validation) and test the final signature(n=70). External validation and hazards modelling were investigated in a retrospective cohort(n=106) of primary LACC treated with curative chemoradiation at our institution(2013-2018). Contiguous sections of FFPE diagnostic biopsies were cut for H&E staining and RNA extraction. H&E slides were reviewed by two consultant histopathologists for histology, grade, and tumour percentage. Extracted RNA was analysed on the Clariom-S platform and hypoxia status calculated. Survival was also assessed in a publicly available cohort(GSE36562). Results Sixty-one DEGs in ≥ 4/5 cell lines were selected(p<0.000001) and 55 mapped onto TCGA data. Unsupervised k-means clustering(k=2) was applied to the training data(Fig 1a). ‘Class 2’ had 31 upregulated genes and was enriched for hypoxia- related processes in The Molecular Signatures Database. The top 5 co-expressed genes in the cluster were vascular endothelial growth factor A(VEGFA), phosphoglycerate kinase 1(PGK1), L-lactate dehydrogenase A(LDHA), 6-phosphofructo- 2-kinase/fructose-2,6-bisphosphatase 2(PFKFB4) and hexokinase-2(HK2; Fig 1b). These are all recognised hypoxia-induced regulators of the glycolysis and pyruvate/lactate pathways. The 31-gene signature was prognostic in the training(Fig 1c) and test(Fig 1d) cohorts. Fig1. (A)candidate gene clustering; (B)Rank correlation of signature genes; (C)Kaplan-Meier (KM) plot in TCGA train; (D)and test groups.