Cleaved NOTCH1 Expression Pattern in Head and Neck Squamous Cell Carcinoma Is Associated with NOTCH1 Mutation, HPV Status, and High-Risk Features

Eleni M Rettig, Christine H Chung, Justin A Bishop, Jason D Howard, Rajni Sharma, Ryan J Li, Christopher Douville, Rachel Karchin, Evgeny Izumchenko, David Sidransky, Wayne Koch, Joseph Califano, Nishant Agrawal, Carole Fakhry

The Notch pathway is frequently altered in HNSCCs, however the clinical significance of NOTCH1 dysregulation is poorly understood. This study was designed to characterize expression of the transcriptionally active NOTCH1 Intracellular Domain (NICD1) in HNSCCs and evaluate its association with NOTCH1 mutation status and clinical parameters. Immunohistochemistry for NICD1 was performed on 79 previously sequenced archival HNSCCs with known NOTCH1 mutation status. Three distinct immunohistochemical staining patterns were identified: positive/peripheral (47%), positive/non-peripheral (34%) and negative (19%). NICD1 expression was associated with NOTCH1 mutation status (p<0.001). Most NOTCH1-wild type tumors were peripheral (55%), while mutated NOTCH1 tumors were most commonly negative (47%). Non-peripheral tumors were more likely than peripheral tumors to have extracapsular spread (aOR 16.01, 95%CI=1.92-133.46, p=0.010) and poor differentiation (aOR 5.27, 95%CI=0.90-30.86, p=0.066). Negative staining tumors tended to be poorly differentiated (aOR 24.71, 95%CI=1.53-399.33, p=0.024) and were less likely to be HPV-positive (aOR 0.043, 95%CI=0.001-1.59, p=0.087). NOTCH1 mutagenesis was significantly associated with HPV status, with NOTCH1-wild-type tumors more likely to be HPV-positive than NOTCH1-mutated tumors (aOR 19.06, 95%CI=1.31-276.15, p=0.031). TP53 disruptive mutations were not associated with NICD1 expression or NOTCH1 mutation. In conclusion, NICD1 is expressed in three distinct patterns in HNSCC that are significantly associated with high-risk features. These findings further support a dual role for NOTCH1 as both tumor suppressor and oncogene in HNSCC. Further research is necessary to clarify the role of NOTCH1 in HNSCC and understand the clinical and therapeutic implications therein.