Abstract 4352: A high rate of episomal HPV16 is present in head and neck squamous cell carcinoma tumors by long-read whole genome sequencing
Authors: Tulsyan Sonam , Mukhina Vera , Rodriguez Isabel , Choudhury Subhendu R. , Allor Erin , Hatte Kyle , Dean Michael , Gaykalova Daria A. 
Published: March 2024

Persistent Human Papillomavirus (HPV) infection causes an increased risk of Head and Neck Squamous Cell Carcinoma (HNSCC). However, a comprehensive understanding of the intricate molecular events within virus-positive tumors remains a critical knowledge gap. Therefore, we used long-read sequencing to study the intricacies of HPV integration events within the genomic landscape of HPV+ HNSCC tumors. A total of 16 tissue biopsies, including 10 tumors and 6 matched adjacent normal tissues from histopathologically confirmed HNSCC subjects were sequenced by LSK114 chemistry of Oxford Nanopore Technology with an average coverage of 30X and 10X, respectively. The predicted mitochondrial haplotype from Mitomaster confirmed that the tumor/normal pair was from the same individual. The HPV integration status was determined by aligning fastq_pass files at the Cancer Genomics Cloud and viewing the breakpoints in the Integrated Genome Viewer. HPV lineage and sub-lineage classification was determined using ClustalOmega. We detected HPV16 in 8/10 tumors, with sublineages A1 and A2 accounting for 38% (3/8) and D3 for 25% (2/8). One tumor sample had a very low HPV load with only one HPV16 sequence read and low detection by PCR. Interestingly, we found that 5/8 HPV positive tumors had episomal HPV16 with different states. So, two tumors had intact HPV episomes, two more had either a small deletion or an insertion in the episomal HPV, and the last one had a rearranged episomal multimer (Table 1). The remaining three tumors had integrated HPV16: one with type 1 integrations at 11q12.13 and two others with type 2 integrations at chr1q42.12 and chr14q21.1. Our results indicate that episomal HPV16 is more prevalent than integrated HPV16 in primary HPV+ HNSCC samples. These findings provide new insights into the molecular mechanisms and consequences of HPV infection in HNSCC. Table 1: HPV characterization in HNSCC studied tissue biopsies.

Patient ID Race HPV status HPV sublineages Predicted Haplotype HPV pattern #PID_1 Caucasian HPV16 + A2 T2b (T2b) Type 2 Integration (chr1q42.12) #PID_2 - HPV- - I1a (I1a1b) - #PID_3 Caucasian HPV16 + A1 H1q (H1q) Episomal (rearranged multimer) PID_4 African American HPV16 + A1 - Episomal (deletion of 636bp from 4892 to 5528) #PID_5 - HPV16 + A2 H1 (H1+16189) Type 1 Integration (complex chr11q12.13) *#PID_6 Caucasian HPV16 + - T2b (T2b) - PID_7 Caucasian HPV16 + D3 - Episomal #PID_8 African American HPV16 + D3 L1c (L1c3a) Type 2 Integration (chr14q21.1) PID_9 African American HPV16 + A2 - Episomal (insertion of 257bp from 7310-7567) PID_10 Caucasian HPV16 + A1 - Episomal *Very weakly HPV16 positive; #Tumor-normal pair

Citation Format: Sonam Tulsyan, Vera Mukhina, Isabel Rodriguez, Subhendu R. Choudhury, Erin Allor, Kyle Hatte, Michael Dean, Daria A. Gaykalova. A high rate of episomal HPV16 is present in head and neck squamous cell carcinoma tumors by long-read whole genome sequencing [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 4352.