Abstract A06: Interrogation of HPV-positive oropharyngeal squamous cell carcinomas with RNA-based Nanostring assay demonstrates expression profile associated with treatment resistance
Authors: Liu Zixing , Mazul Angela , Griffith Malachi , Zolkind Paul 
Published: September 2020

Abstract
Background: Human papilloma virus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is an increasingly common malignancy and public health challenge. HPV-associated OPSCCs typically respond to treatment, and there is an increasing focus on deintensification trials to minimize treatment related morbidity. However, treatment failure rates in locally advanced HPV-associated OPSCC range from 14%-32%, and there is a need to interrogate potential biomarkers of treatment response and resistance to guide patient stratification for deintensification trials and to identify novel treatment targets for high-risk patients.
Methods: We prospectively identified a cohort of 8 patients with HPV-associated OPSCC who subsequently developed a biopsy-proven tumor recurrence. We also identified 8 patients with HPV-associated OPSCC matched to the above cohort by gender, smoking history, TNM stage, and treatment modality who developed a complete response to treatment. The primary samples of each cohort were interrogated with an RNA-based Nanostring immuno-oncology assay.
Results: We identified that treatment-responsive tumors had significantly higher expression of NK cell markers than nonresponders (KIR3DL2, q=0.003, KIR2DL3, q=0.04). These data may indicate a potential role of the innate immune system in tumor eradication. We also identified increased expression of CCL21 in treatment-resistant tumors (q=0.04), a biomarker that has been explored in colorectal cancer due to its association with cancer stem cell-like properties. Interrogation of the tumors by smoking status demonstrated that smokers had significantly higher expression of FGF18 (q=0.003), a fibroblast growth factor linked to epithelial-to-mesenchymal transition and cisplatin resistance. We also looked at the immune checkpoint B7-H3 (CD276), a novel immunotherapeutic target associated with worse outcomes in head and neck cancer. We demonstrate that B7-H3 expression is associated with expression of epithelial-to-mesenchymal transition markers such as TWIST1 (q= 0.01), SOX11 (q= 0.006), COL5A1 (q=0.0001), and CXCL8 (q=0.02). Interestingly, low expression of B7-H3 is associated with increased CD8B expression.
Conclusion: In this genomic analysis of HPV-associated oropharyngeal squamous cell carcinomas, we identify an association between presence of NK cells in the tumor microenvironment and treatment responsiveness. We also identify CCL21 as a potential biomarker of treatment resistance. Further studies are needed to confirm these biomarkers and examine the link between smoking status and immune microenvironment. Finally, we demonstrate that the immune checkpoint B7-H3 is associated with markers of epithelial-to-mesenchymal transition and warrants further exploration as a novel therapeutic target.
Citation Format: Zixing Liu, Angela Mazul, Malachi Griffith, Paul Zolkind. Interrogation of HPV-positive oropharyngeal squamous cell carcinomas with RNA-based Nanostring assay demonstrates expression profile associated with treatment resistance [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr A06.