Abstract B030: Novel strategy to improve response of high risk HPV+ HNSCC to radiation therapy
Authors: Vemulamanda Sri , Issaeval Natalia , Kothari Aditi , Schrank Travis , Yarbrough Wendell G. 
Published: January 2025

Abstract
Background: Improving understanding of head and neck squamous cell carcinoma (HNSCC) has led to the discovery of novel molecular markers to stratify risk and guide treatment decisions. Recently, we have identified two subtypes of HPV+ OPSCC – one with good prognosis and one with poor prognosis. The subtypes are distinct in many ways – somatic genes mutated, HPV viral oncogenes expression, the physical state of the viral genome (integrated vs episomal), as well as global mutation and methylation profiles. Intriguingly, all differences converge on intrinsic tumor NF-κB activity with constitutively active NF-κB (usually arising from genetic defects in NF-κB regulators, including TRAF3 and CYLD) driving significantly elevated radiation sensitivity and improved patient survival. NF-κB-based groups define an important clinically actionable prognostic biomarker in HPV+ HNSCC: one important goal is to de-escalate therapy for patients with molecularly low-risk tumors to improve quality of life amongst survivors, while another goal is to improve the cure for of patients with a high risk of treatment failure. Material and methods: We utilized HPV+ head and neck cancer cells, HPV+ HNSCC xenografted mouse model, patient-derived xenografts (PDX), as well as our novel fully immunocompetent mouse model of high risk HPV+ HNSCC; we applied targeted fractionated radiation. To activate NF-κB, we used two clinically applicable drugs with different mechanisms of action: Toll-like receptor 5 (TLR5) agonist and mitochondria-derived activator of caspases (SMAC) mimetic. Custom NF-κB NanoString panel contains our recently developed NF-κB gene signature along with HPV genes and housekeeping genes that are used to normalize the gene expression data. Results: Both drugs activated NF-κB in HPV+ HNSCC and significantly improved response of HPV+ head and neck cancer cells and tumors to radiation. Interestingly, TLR5 agonist alone had a strong tumor suppressing effect in low NF-κB HPV+ HNSCC; this effect was significantly better than 32 Gy focused radiation given in fractions of 4 Gy. Custom NF-κB NanoString panel is robustly prognostic with NF-κB active tumors having improved outcomes after chemoradiation. Conclusions: Because of the average relatively favorable prognosis of HPV+ HNSCC, urgent need for improved therapy for patients with aggressive high risk tumors is greatly undervalued. Here, we present a clinical assay to risk stratify patients with HPV+ HNSCC and begin to explore pharmacological activation of NF-κB as a strategy to sensitize high risk HPV+ HNSCC to radiation therapy. TLR5 agonist is well known for the remarkable normal tissue protective effects against radiation and other damaging conditions; the dual effect of entolimod – sensitization of HPV+ HNSCC to radiation, while simultaneously protecting normal tissues from severe side effects - may be useful for patients with high-risk HPV+ head and neck cancer in combination with radiotherapy.
Citation Format: Sri Vemulamanda, Natalia Issaeva1, Aditi Kothari, Travis Schrank, Wendell G. Yarbrough. Novel strategy to improve response of high risk HPV+ HNSCC to radiation therapy. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr B030.