Use of DNA repair pathway analysis to predict overall survival in head and neck cancer patients treated with TFHX chemoradiotherapy

Abstract

6033 Background: Concurrent chemoradiotherapy is a standard-of-care for head and neck cancer. Radiotherapy and chemotherapeutic agents damage DNA; lack of adequate repair induces tumor cell death. The network of DNA repair pathways was examined to predict TFHX chemoradiotherapy outcomes. Methods: Biopsy specimens (paraffin) from 60 HNC patients were evaluated from tissue microarrays. Samples originated from patient groups from phase I/II studies: 1) poor-prognosis radiation-naïve, 2) re-irradiation. All were treated with TFHX-based chemoradiotherapy. DNA repair biomarkers XPF, pMK2, PAR, pH2AX, FANCD2, ATM, BRCA1, RAD51, ERCC1 (clone 8F1), and p53 were explored using IHC, automated image processing, and machine reading (>500 cells/read), for nuclear and cytoplasmic quantity, area, and intensity, and correlated with clinical outcome. Results: There was low inter-core variability per tumor with median patient ranking signal to noise ratio of 15.0 across all markers. Patients were stratified into short and long survival groups by determination of critical marker thresholds. Five DNA repair biomarkers (RAD51, ATM, BRCA1, XPF, FANCD2) exhibited univariate significance for overall survival (p = 2.65e-3, 1.53e-2, 4.77e-4, 8.57e-5, 1.32e-3)(additional clinical parameters multivariate analysis was not feasible due to sample size). ERCC1 was not statistically significant (p = 1.0). Pairwise biomarker combinations improved survival group discrimination. Combination of 4 DNA repair biomarkers (FANCD2, BRCA1, ATM, XPF) was also significant (p = 1.31e-4). Discriminant analysis demonstrated higher fractions of correctly identified patients in good/poor survival groups from four-marker tests. Conclusions: Five DNA repair biomarkers predicted overall survival following TFHX-based chemoradiotherapy. By contrast ERCC1 (8F1) was not significant. Combination of markers improved predictive ability in this study. The analysis of DNA repair pathways, particularly in homologous recombination, DNA damage response, and nucleotide excision repair, may be clinically useful. Validation in a larger, homogeneous patient population, and using platinum-based chemoradiotherapy, is indicated and currently ongoing. [Table: see text]