Resumen

Background

The incidence of oropharyngeal squamous cell carcinomas (OPSCCs) associated with oncogenic human papillomavirus (HPV), such as HPV-16, is rapidly increasing worldwide. The presence of HPV in OPSCC confers improved overall- and progression-free survival, relative to HPV-negative tumors. This opens the possibility for de-escalation treatments in HPV-positive OPSCC patients. However, 30% HPV-positive OPSCC patients have an unfavorable outcome, indicating that HPV-positive OPSCC are heterogeneous tumors. Therefore, identifying markers able to predict HPV-positive OPSCC outcome should be useful to design therapeutic protocols ad-hoc for HPV-positive OPSCC patients.

Hypothesis

In this study, the HPV status will be investigated to verify whether HPV DNA, either integrated and/or in the episomal form, could impact the OPSCC patient outcome. Indeed, HPV status may influence the E6/E7 antibody response and gene methylation of host's cells. Therefore, combining markers of HPV status and host cell gene methylation can likely be used as reliable biomarkers of HPV-positive OPSCC outcome.

Aims

1. Determine HPV-16 status in HPV-positive OPSCC cases and its association with disease outcome in HPV-positive OPSCC patients. We hypothesize that different HPV-16 DNA status could be associated with different disease outcomes in HPV-positive OPSCC patients.
2. Examine the impact of adding molecular variations on host cell genes, such as gene methylation, to existing prognostic factors for HPV-positive OPSCC currently based on patient characteristics and clinical factors, such as age, tumor stage, histological grade and HPV test. We hypothesize that methylation-induced variations in gene expression of host cells, combined with the HPV DNA status, will improve the performance of these factors in predicting prognosis of HPV-positive OPSCC patients.

Experimental Design

The proposed project will be carry out in HPV-positive OPSCC tissue and serum samples of HPV-positive OPSCC patients. Specifically, 1) OPSCC tissues will be investigated for HPV status such as DNA viral load, DNA status (episomal vs integrated), genotyping, HPV E5, E6, E7 gene expression, and expression/status of cell genes, such as p16, EGFR and p53 gene (wild type vs mutated) using Real Time PCR techniques and DNA sequencing analyses. Sera will be analyzed for HPV E6/E7 antibodies by ELISA assay. 2) OPSCC tissues will be used to derive primary OPSCC keratinocytes, which will be investigated for: a) HPV status and HPV expression and b) microarray analysis, and c) gene methylation profile.

Expected Results

In HPV positive OPSCC, we expect to identify different HPV status, each associated with a specific E6/E7 serologic profile and a specific gene methylation profile of host cell. These results will allow to identify different molecular signatures associated to HPV-positive OPSCC. Following the disease outcome in post-treated HPV-positive OPSCC patients, we will be able to associate the different molecular signatures with favorable or poor disease outcome.

Impact On Cancer

This study will identify reliable prognostic biomarkers to predict the disease outcome in HPV-positive OSCC patients. These prognostic biomarkers, in turn, will allow to design therapeutic protocols ad-hoc for HPV-positive OPSCC patients.