Abstract P133: NF-κB and NRF2 pathways dysregulation is associated with improved outcomes in HPV-associated head and neck cancer
Authors: Kothari Aditi , Schrank Travis Parke , Yarbrough Wendell Gray , Isaeva Natalia 
Published: December 2021

Abstract
This study aims to better understand the mechanisms of HPV carcinogenesis. Additionally, it helps to improve therapeutic personalization, identify new therapeutic targets in cancer, and aids in understanding the role of NF-κB in HPV-driven carcinogenesis, HPV biology, and tumor response to therapy. The incidence of HPV-associated (HPV+) head and neck cancer (HNSCC) is increasing rapidly, however, the mechanisms of HPV-driven carcinogenesis in head and neck cancers have not been thoroughly investigated. The relatively favorable prognosis of HPV+ HNSCC, along with severe side-effects seen in patients due to radiotherapy, it is pertinent to develop de-intensification strategies. However, a reliable prognostic biomarker is a limiting factor for clinical trials aiming to decrease the morbidity of therapy for HPV+ HNSCC through treatment de-escalation. Using molecular characteristics of HPV+ HNSCC and based on the presence or absence of NF-κB activating mutations in TCGA head and neck cancer cohort, we developed an NF-kB activity classifier and identified two intrinsic subtypes of HPV+ HNSCCs. The subtype harboring mutations in NF-κB regulators is associated with activated NF-κB, maintenance of episomal HPV, and improved patient survival. Identification of a subtype of HPV+ HNSCC with active NF-κB, improved survival, and absence of HPV genome integration, suggested that these tumors were driven by a distinct or alternative mechanism of oncogenesis that is dependent on episomal HPV and NF-κB activity, while classical HPV-driven carcinogenesis relies on increased expression of HPV E6 and E7 oncogenes occurring upon HPV genome integration and loss of HPV E2.However, it is not yet known why this subset of tumors with overactive NF-κB displays better survival. An interesting finding from our study was that these tumors with increased NF-κB activity had reduced NRF2 signaling.NRF2 has been associated with resistance to treatment and significant downregulation of NRF2 signaling in the subtype of HPV+ HNSCC with active NF-κB may contribute to increased treatment sensitivity and improved patient survival. Preliminary experiments confirmed that baseline and inducible (with small molecule NRF2 activator or radiation treatment) NRF2 transcriptional activity is downregulated in HPV-positive head and neck cancer cells with deleted CYLD or TRAF3 and activated NF-κB, and that this effect is most likely independent of NRF2 degradation mediated by Cul3. Moreover, expression of major NRF2 targets was decreased in HPV+ HNSCC cells harboring constitutively active NF-κB. Finding an inverse correlation between NF-κB and NRF2 activities suggests that inhibition of NRF2 in NF-κB active HPV+ HNSCCs drives their sensitivity to radiation and that NF-κB regulates NRF2 transcriptional activity in HPV+ HNSCC. This project uncovers the role of NF-κB in HPV-driven head and neck cancer etiology. Our novel NF-κB activity RNA classifier or mutations in NF-κB pathway distinguishing the 2 subtypes of HPV+ HNSCC may serve as prognostic biomarkers to help clinicians with therapeutic decisions.
Citation Format: Aditi Kothari, Travis Parke Schrank, Wendell Gray Yarbrough, Natalia Isaeva. NF-κB and NRF2 pathways dysregulation is associated with improved outcomes in HPV-associated head and neck cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P133.