ESTRO 2020 Abstract Book

S168 ESTRO 2020

gene expression technologies were assessed (Taqman array cards, RNA-seq, Affymetrix Clariom S). Results The 24 prospective samples (age <12 months) yielded higher quality RNA than the retrospective samples (p = 0.008). Success rate of gene expression using Clariom S was achieved in 560 samples (84%). All samples passed QC metric and all 28 genes of the prostate HS were detected and measurable. RNA quality (r=0.03) and yield (r=-0.05) did not correlate with HS. HS did not increase with Gleason grade group (G3 2.40±0.16, G4 2.31±0.30, G5 2.69±0.22). Clariom S consistently outperformed the other platforms studied. There was an inverse correlation between probe amplicon length and gene expression (n=33, r=-0.67) with the Taqman array card. Intratumour heterogeneity based on HS group was demonstrated in 18 samples (45%). No correlation was seen between histopathological adverse features and HS. Conclusion This is the largest prostate radiotherapy cohort with full gene expression data available and hence a valuable resource for research. The Clariom S gene expression platform was superior to Taqman array cards and RNA-seq for validation of a prostate hypoxia gene signature in definitive radiotherapy cohorts using archival FFPE NC. OC-0320 Correlations of tissue and imaging hypoxia biomarkers during chemoradiation of HNSCC patients N.H. Nicolay 1,2 , G. Kayser 3 , N. Wiedenmann 1,2 , M. Mix 2,4 , M. Werner 3 , A. Grosu 1,2 1 Universitätsklinikum Freiburg, Department of Radiation Oncology, Freiburg, Germany ; 2 Deutsches Krebsforschungszentrum, DKTK Partner Site Freiburg, Heidelberg, Germany ; 3 Universitätsklinikum Freiburg, Department of Pathology, Freiburg, Germany ; 4 Universitätsklinikum Freiburg, Department of Nuclear Medicine, Freiburg, Germany Purpose or Objective Tumor hypoxia impairs the response of head-and-neck cancer (HNSCC) patients to radiotherapy and can be detected both by tissue biomarkers and PET imaging. However, the value of hypoxia biomarkers and imaging for predicting HNSCC patient outcomes are incompletely understood, and potential correlations between tissue and PET data remain to be elucidated. Here, we performed exploratory analyses of potential correlations between tissue-based hypoxia biomarkers and longitudinal hypoxia imaging in a prospective trial of HNSCC patients. Material and Methods 49 patients undergoing radiochemotherapy for locally advanced HNSCCs were enrolled in this prospective exploratory trial. They underwent baseline biopsies and [ 18 F]FMISO PET imaging at weeks 0, 2 and 5 during treatment. Immunohistochemical analyses for hypoxia- associated tissue markers HIF1α, CAIX, CD34 as well as biomarkers for other cellular functions influenced by hypoxia (proliferation: Ki67, cancer stem cells: CD44, DNA repair: Ku80) were assessed, and HPV status was investigated by p16 staining and HPV DNA analyses. Biomarker expression was quantified by the H-score and correlated with biological imaging information (Pearson product-moment correlation coefficient) and patient outcome data (Cox regression analysis). Results High HIF1α tumor levels significantly correlated with increased tumor hypoxia at during the first two weeks of treatment as assessed by the difference in the [ 18 F]FMISO tumor-to-background ratios (r=0.35; p<0.05), and high

HIF1α and CAIX expression were both associated with a deferred decrease in hypoxia between weeks 2 and 5 (r=0.35; p<0.05 for HIF1α; r=-0.39; p<0.05). Locoregional recurrence rates after radiotherapy were significantly higher in patients with high CAIX expression (hazard ratio 2.80 [1.08 – 7.31]; p<0.05) and also increased for high levels of Ku80 as a biomarker for radiation-induced DNA double strand breaks, although this correlation did not reach statistical significance. HPV status did not correlate with any of the tested hypoxia biomarkers, and HPV- positive patients showed lower loco-regional recurrence rates (hazard ratio 0.13 [0.02 – 0.99]; p<0.01) and progression-free survival (hazard ratio 0.232 [0.055– 0.983]; p=0.047) independent of their hypoxia dynamics and expression of hypoxia-associated tissue biomarkers. Conclusion In this exploratory trial, high expression of the tissue- based hypoxia biomarkers HIF1α and CAIX correlated with adverse hypoxia dynamics in HNSCCs during radiochemotherapy as assessed by PET imaging, and high CAIX levels were associated with increased loco-regional recurrence rates. Hence, hypoxia biomarkers warrant further investigations as potential predictors of hypoxia dynamics and hypoxia-associated radiation resistance. OC-0321 Transcriptional subtypes in primary and recurrent head and neck squamous cell carcinomas H. Zitzelsberger 1,2,3 , P. Weber 1,3 , A. Kuenstner 4 , J. Hess 1,2,3 , S. Marschner 2,3 , C. Idel 5 , J. Ribbat-Idel 6 , C. Walz 7 , A.K. Walch 8 , S. Perner 9 , K. Unger 1,2,3 , H. Busch 4 , B. Wollenberg 5 , C. Belka 2,3 1 Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Research Unit Radiation Cytogenetics, Munich, Germany ; 2 University Hospital LMU Munich, Department of Radiation Oncology, Munich, Germany ; 3 Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Clinical Cooperation Group "Personalized Radiotherapy in Head and Neck Cancer", Munich, Germany ; 4 University of Luebeck, Luebeck Institute of Experimental Dermatology and Institute for Cardiogenetics, Luebeck, Germany ; 5 University Hospital Schleswig Holstein Campus Luebeck, Clinic for Otorhinolaryngology - Head and Neck Surgery, Luebeck, Germany ; 6 University Hospital Schleswig- Holstein Campus Luebeck, Institute of Pathology, Luebeck, Germany ; 7 Ludwig-Maximilians University, Institute for Pathology, Munich, Germany ; 8 Helmholtz Zentrum Muenchen - German Research Center for Environmental Health, Research Unit Analytical Pathology, Munich, Germany ; 9 University Hospital Schleswig Holstein Campus Luebeck, Institute of Pathology, Luebeck, Germany Purpose or Objective Patients suffering from advanced head and neck squamous cell carcinomas (HNSCC) are at high risk for developing local and loco-regional recurrences after radiochemotherapy. To elucidate molecular processes associated with tumor recurrences we investigated pairs of primary and relapsed tumors in HPV-negative patients after radiochemotherapy treatment at genome and Tissue samples of 34 pairs of retrospectively collected primary and recurrent tumors of locally advanced HNSCC patients were subjected to whole RNA, exome sequencing and PD-L1 expression profiling. The primary tumors of a retrospectively collected cohort of HNSCC (n=74) was subjected to whole RNA sequencing and PD-L1 profiling. transcriptome levels. Material and Methods