Abstract 5060: Role of molecular driver mutations in recurrence of early stage laryngeal cancer following narrow field definitive radiotherapy
Authors: Segura Aaron , Nissen Emily , Lominska Chris , Morse Ryan , Morgan Deri , Neupane Prakash , Pei Dong , Koestler Devin , Kimple Randall , Duvvuri Umamaheswar , Sykes Kevin , Thomas Sufi , Nallani Rohit , Shnayder Lisa , Kakarala Kiran , Yilmaz Emrullah , Bur Andres 
Published: March 2024

Abstract
PURPOSE/OBJECTIVES
Recurrent early-stage laryngeal cancer poses profound clinical and prognostic dilemmas. The primary endpoint of this study was to identify patient exome differences between early-stage laryngeal cancer patients who responded or rapidly progressed following definitive, narrow field radiotherapy. Our study offers the first exploration of mutation patterns in early-stage laryngeal head and neck squamous cell carcinoma (HNSCC) patients receiving curative radiation therapy.
MATERIALS/METHODS
We identified 36 early-stage laryngeal (T1 = 8, T1a = 4, T1b = 2, T1c = 1, T2 = 20, NA =1) HNSCC patients from the University of Kansas Medical Center treated with definitive narrow field radiotherapy to 63-70 Gray (gy) dose. Whole exome sequencing was performed in all patients. Patients were stratified into “responders” (never failed, N=14) and “non-responders” (recurrence &lt;12 months, N=21). Most non-responder patients with local recurrence underwent total salvage laryngectomy (TSL, N=18). All patients underwent whole exome sequencing. The Genome Analysis Toolkit (GATK) was used for pre-processing and functional annotation of variants. Cancer driver genes were detected for each group using the OncodriveCLUST algorithm. Differentially mutated genes were assessed using Fisher’s exact or exact McNemar’s test at P &lt; 0.05. Tumor mutational burden (TMB) comparisons employed the Wilcoxon rank-sum test with the same threshold. For pathway analysis in Reactome and Ingenuity, a P &lt; 0.1 was used for exploratory significance.
RESULTS
Mutation analysis identified distinct cancer driver genes between responders, (N=3), non-responders (N=36), and post-TSL (N=4). Among 75 genes with significant pre-treatment mutation differences between responders and non-responders, KCNT2 and AGAP6 were exclusively mutated in non-responders (OR=0, P=0.005 and OR=0, P=0.027, respectively), ADAMTS7 was solely mutated in responders (OR=inf, P=0.019), and PLEC showed more mutations in responders (OR=11.6, P=0.006). Pathway analysis showed these genes were involved in the RND2 GTPase cycle, protein O-glycosylation related diseases, and apoptotic pathways. Post-treatment analysis indicated an enrichment of mutations in apoptosis regulation pathways, with genes like PLEC being more frequently mutated in responders than in non-responders or TSL patients. In addition, we observed in non-responders that they trended towards higher median pre-treatment TMB compared to responders (7.98 vs 6.16, P=0.072). There was no significant difference in TMB between TSL patients and responders or non-responders pre-treatment.
CONCLUSION
Our analysis reveals distinct mutation patterns in early-stage laryngeal cancer patients by response to radiotherapy and the potential role of these mutated genes in apoptosis related pathways.
Citation Format: Aaron Segura, Emily Nissen, Chris Lominska, Ryan Morse, Deri Morgan, Prakash Neupane, Dong Pei, Devin Koestler, Randall Kimple, Umamaheswar Duvvuri, Kevin Sykes, Sufi Thomas, Rohit Nallani, Lisa Shnayder, Kiran Kakarala, Emrullah Yilmaz, Andres Bur. Role of molecular driver mutations in recurrence of early stage laryngeal cancer following narrow field definitive radiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5060.