Abstract 2520: Detection of transcriptional active HPV 16/18 in patients with oropharyngeal squamous cell carcinoma by dual immunohistochemistry p16INK4 and in situ hybridization E6/E7 mRNA in archival material older than 25 years

Abstract

Abstract Introduction: Determination of Human Papillomavirus (HPV) status in oropharyngeal squamous cell carcinomas (OPSCC) is important because it influences the therapeutic decision. A dual protocol combining immunohistochemistry (IHC) for detection of p16INK4 overexpression with in situ hybridization (ISH) for mRNA E6/E7 detection may improve the accuracy of determining the HPV status in OPSCC patients. The aim of this study was to optimize a multiplex method for simultaneous detection of p16 and mRNA E6/E7 on the same formalin-fixed paraffin-embedded (FFPE) tissue samples. Methods: IHC for the detection of p16INK4 and chromogenic ISH for mRNA E6/E7 were combined in different sequences and with different intermediate steps for fixation on OPSCC tissue samples from primary tumors and lymph node metastases. Archival tissue samples stored at Department of Pathology at Haukeland University Hospital since 1990 has been used for tests. Results: A combined method for simultaneous detection of p16INK4 and mRNA E6/E7 transcripts on the same tissue slides were successfully developed. Active HPV status was detected in OPSCC tissue samples from both primary and metastatic lymph nodes for all cases tested, including tissue samples stored for 30 years. The result was correlated to DNA HPV status. Conclusion: This study confirms that a more precise detection of active HPV infection is possible on FFPE tissue slides. This method could be easily implemented in clinical settings for more specific stratification of OPSCC patients. At the same time, the method is also robust and sensitive on retrospective archival material, and this could be used for answering important research questions on HPV-related OPSCC. Citation Format: Stian Tornaas, Siren Fromreid, Hans Jørgen Aarstad, Olav Karsten Vintermyr, Daniela Elena Costea, Harsh Nitin Dongre. Detection of transcriptional active HPV 16/18 in patients with oropharyngeal squamous cell carcinoma by dual immunohistochemistry p16INK4 and in situ hybridization E6/E7 mRNA in archival material older than 25 years [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2520.