HPV-Positive and HPV-Negative Vulvar Squamous Cell Carcinoma Are Biologically, but Not Clinically, Distinct

BACKGROUND: Vulvar squamous cell carcinoma (VSCC) pathogenesis is traditionally defined by the presence or absence of human papillomavirus (HPV), but the definition of these groups and their molecular characteristics remains ambiguous across studies. OBJECTIVE: The hypothesis of this project was that HPV-positive and HPV-negative VSCC are distinct diagnoses with unique biomarkers and clinically distinct behaviors. The objective was to determine the clinical and biologic relevance of these two groups in VSCC. METHODS: A retrospective cohort analysis of 36 patients with invasive VSCC was performed where HPV status was determined using RNA in situ hybridization (ISH) and polymerase chain reaction (PCR). Clinical annotation, p16 immunohistochemistry (IHC), programmed death ligand-1 (PD-L1) IHC, HPV16 circular E7 RNA (circE7) detection, and RNA-sequencing (RNA-seq) of the cases was performed. RESULTS: A combination of ISH and PCR identified 20 cases (55.6%) as HPV-positive. HPV-status did not impact overall survival (HR: 1.36, 95% CI: 0.307 to 6.037, p=0.6857) or progression-free survival (HR: 1.12, 95% CI: 0.388 to 3.22, p=0.8367), and no significant clinical differences were found between the groups. PD-L1 expression did not correlate with HPV status, but increased expression of PD-L1 correlated with worse overall survival. Transcriptomic analyses (n=23) revealed distinct groups, defined by HPV status, with multiple differentially expressed genes previously implicated in HPV-induced cancers. HPV-positive tumors showed higher global expression of endogenous circular RNAs (circRNAs), including several circRNAs that have previously been implicated in the pathogenesis of other cancers. CONCLUSIONS: In summary, this retrospective cohort analysis did not detect clinical differences between HPV-positive and HPV-negative cases or an association with biomarkers, PD-L1 and circE7. The transcriptomic analysis of VSCC confirmed the biological distinction between these two groups in VSCC and suggested specific diagnostic and therapeutic targets for future studies, including several circRNAs.