[Human papillomavirus and squamous cell cancer of the head and neck region : Prognostic, therapeutic and prophylactic implications]

Hypofractionated Radiotherapy Upregulates Several Immune Checkpoint Molecules in Head and Neck Squamous Cell Carcinoma Cells Independently of the HPV Status While ICOS-L Is Upregulated Only on HPV-Positive Cells

While the treatment of squamous cell carcinoma of the head and neck (HNSCC) with radiotherapy (RT) is complemented more and more by immunotherapy in clinical trials, little is known about the impact of the human papillomavirus (HPV) status or the applied RT scheme on the immune phenotype of the tumor cells. Therefore, we aimed to examine the impact of the HPV status of four human HNSCC cell lines on cell death and the expression of immune checkpoint molecules (ICMs) after RT with either hypofractionation irradiation (5x3.0Gy) or a high single dose (1x19.3Gy) via multicolor flow cytometry and quantitative PCR at an early time point after therapy. In our study, 5x3.0Gy RT induced high numbers of early and late apoptotic cells independent of the HPV status, but necrosis was only increased in the HPV-positive UM-Scc-47 cells. Generally, the immune stimulatory ICMs (CD70, CD137-L, ICOS-L) were less affected by RT compared to the immune suppressive ones (PD-L1, PD-L2, and the herpesvirus entry mediator (HVEM)). A significant higher surface expression of the analyzed ICMs was found after hypofractionated RT compared to a single high dose; however, regardless of the HPV status, with the exception of ICOS-L. Here, HPV-positive HNSCC tumor cells showed a stronger response to 5x3.0Gy than HPV-negative ones. On the RNA level, only minor alterations of ICMs were observed following RT, with the exception of the HPV negative cell line CAL33 treated with 5x3.0Gy, where PD-L2, HVEM and CD70 were significantly increased. We conclude that the HPV status may not distinctly predict immunological responses following RT, and thus cannot be used as a single predictive marker for therapy responses in HNSCC. In contrast, the patient-specific individual expression of ICMs following RT is preferable for the targeted patient selection for immune therapy directed against distinct ICM.

The Modifying Effect of a Functional Variant at the miRNA Binding Site in E2F1 Gene on Recurrence of Oropharyngeal Cancer Patients with Definitive Radiotherapy

Human papillomavirus (HPV) activates E2F1-driven transcription via the E7-RB-E2F1 pathway. A polymorphism in the 3' UTR of E2F1 gene may disrupt a binding site for miRNA and may affect its transcription level, thus modifying the susceptibility to radiotherapy and outcomes through this pathway. We evaluated the association of a polymorphism at the 3'UTR miRNA binding site of E2F1 gene (rs3213180) with risk of recurrence of SCCOP in a cohort of 1008 patients. Log-rank test and univariate and multivariable Cox models were used to evaluate the associations. Compared with patients with E2F1-rs3213180 GG homozygous genotype, the patients with E2F1-rs3213180GC+CC variant genotypes had significantly better disease-free survival (log-rank P<.001) and decreased risk of SCCOP recurrence (HR, 0.4, 95% CI, 0.3-0.5) after multivariable adjustment. Furthermore, among patients with HPV16-positive tumors, the patients with E2F1-rs3213180 GC+CC variant genotypes had significantly better disease-free survival rates (log-rank P<.001) and lower recurrence risk than those with E2F1-rs3213180 GG homozygous genotype (HR, 0.2, 95% CI, 0.1-0.4). Our findings suggest that E2F1-rs3213180 polymorphism may modulate the risk of recurrence in SCCOP patients, particularly for patients with HPV16-positive tumors of SCCOP. However, future larger population and functional studies are warranted to validate these results.