Abstract 477: Correlation of PD-L1 expression and HPV status among primary and metastasized HNSCC tumors

Abstract

Dysregulation of the immune checkpoints has been identified as one of the mechanisms tumor cells employ for immune escape. Human papillomavirus (HPV) plays an important role in the etiology of one subset of Head and Neck Squamous Cell Carcinomas (HNSCC). Recent studies reported that PD-1/PD-L1 pathway may be correlated with HPV-associated HNSCC. The degree of PD-L1 expression has been reported to be increased in those patients with HPV-positive disease. Also, PD-L1 expression in HNSCC was observed in the primary, recurrent, and metastatic disease setting. However, the clinicopathological implications associated with PD-L1 in HNSCC, as well as in disease metastasis, remain largely unclear. Using immunohistochemistry (IHC) and In situ hybridization (ISH) on VENTANA BenchMark ULTRA automated stainers, 40 cases of HNSCC, with matching primary and metastatic cancer stages, were evaluated for expression of PD-L1, p16, a surrogate marker of transforming HPV infections, and presence of HPV. Formalin-fixed paraffin-embedded tumor samples were subjected to PD-L1- and p16-IHC as well as HPV-ISH. A potential association between PD-L1 expression and HPV status among primary tumors and matched metastases was analyzed. Our data show that expression of PD-L1 or p16 is concordant in the majority of HNSCC primary vs metastatic tumor cases tested. Agreement rate of p16 expression among 40 case pairs of primary vs metastatic tumor was 88.2% with a 95% Confidence Interval (CI) of (73.4-95.3). PD-L1 expression was 76.9% (61.7-87.4) concordant among the 40 case pairs. Agreement rate between PD-L1 and p16 was 77.1% (61.0-87.9) in primary cases and 51.3% (35.9-66.6) in metastatic cases. No obvious association between PD-L1 and p16 expression was observed. Citation Format: Chenglu C. Quon, Xiaoling Xia, Lupe Manriquez, Crystal Schemp, Dawn Sloane, Shahad Alabagi, Mohammed G. Abdelwahab, Pengfei Gu, Lizhen Pang, Khalid Hanif, Nicole Schechter. Correlation of PD-L1 expression and HPV status among primary and metastasized HNSCC tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 477.