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Precancerous cells in the oral cavity may appear as oral potentially malignant disorders, but they may also present as dysplasia without visual manifestation in tumor-adjacent tissue. As it is currently not possible to prevent the malignant transformation of these oral precancers, new treatments are urgently awaited. Here, we generated precancer culture models using a previously established method for the generation of oral keratinocyte cultures and incorporated CRISPR/Cas9 editing. The generated cell lines were used to investigate the efficacy of a set of small molecule inhibitors. Tumor-adjacent mucosa and oral leukoplakia biopsies were cultured and genetically characterized. Mutations were introduced in CDKN2A and TP53 using CRISPR/Cas9 and combined with the ectopic activation of telomerase to generate cell lines with prolonged proliferation. The method was tested in normal oral keratinocytes and tumor-adjacent biopsies and subsequently applied to a large set of oral leukoplakia biopsies. Finally, a subset of the immortalized cell lines was used to assess the efficacy of a set of small molecule inhibitors. Culturing and genomic engineering was highly efficient for normal and tumor-adjacent oral keratinocytes, but success rates in oral leukoplakia were remarkably low. Knock-out of CDKN2A in combination with either the activation of telomerase or knock-out of TP53 seemed a prerequisite for immortalization. Prolonged culturing was accompanied by additional genetic aberrations in these cultures. The generated cell lines were more sensitive than normal keratinocytes to small molecule inhibitors of previously identified targets. In conclusion, while very effective for normal keratinocytes and tumor-adjacent biopsies, the success rate of oral leukoplakia cell culturing methods was very low. Genomic engineering enabled the prolonged culturing of OL-derived keratinocytes but was associated with acquired genetic changes. Further studies are required to assess to what extent the immortalized cultures faithfully represent characteristics of the cells in vivo. [ABSTRACT FROM AUTHOR]

Oral squamous cell carcinomas (OSCCs) develop in genetically altered epithelium in the mucosal lining, also coined as fields, which are mostly not visible but occasionally present as white oral leukoplakia (OL) lesions. We developed a noninvasive genetic assay using next‐generation sequencing (NGS) on brushed cells to detect the presence of genetically altered fields, including those that are not macroscopically visible. The assay demonstrated high accuracy in OL patients when brush samples were compared with biopsies as gold standard. In a cohort of Fanconi anemia patients, detection of mutations in prospectively collected oral brushes predicted oral cancer also when visible abnormalities were absent. We further provide insight in the molecular landscape of OL with frequent changes of TP53, FAT1 and NOTCH1. NGS analysis of noninvasively collected samples offers a highly accurate method to detect genetically altered fields in the oral cavity, and predicts development of OSCC in high‐risk individuals. Noninvasive genetic screening can be employed to screen high‐risk populations for cancer and precancer, map the extension of OL lesions beyond what is visible, map the oral cavity for precancerous changes even when visible abnormalities are absent, test accuracy of promising imaging modalities, monitor interventions and determine genetic progression as well as the natural history of the disease in the human patient. [ABSTRACT FROM AUTHOR]

The prognostic impact of human papillomavirus (HPV) in oropharyngeal cancer is generally acknowledged, and HPV‐status is assessed routinely in clinical practice. Paradoxically, while the oral cavity seems the predilection site for productive HPV‐infections, figures on HPV‐attribution in oral cavity squamous cell carcinoma (OCSCC) differ widely, and prognostic impact is uncertain. Major obstacles are the lack of reproducible assays to detect HPV in nonoropharyngeal cancers, the relatively small cohorts studied and consequently the shortfall of convincing data. In our study, we used a validated, nucleic acid‐based workflow to assess HPV‐prevalence in a consecutive cohort of 1016 OCSCCs, and investigated its prognostic impact. In parallel, we analyzed p16‐immunohistochemistry (p16‐IHC) as surrogate marker for transforming HPV‐infection and independent prognosticator. All OCSCC‐patients diagnosed between 2008 and 2014 at two Dutch university medical centers were included (N = 1069). Formalin‐fixed, paraffin‐embedded (FFPE)‐samples of 1016 OCSCCs could be retrieved. Punch biopsies were taken from the tumor area in the FFPE‐blocks and tested for HPV. P16‐IHC was performed on 580 OCSCCs, including all HPV‐positive tumors. From 940 samples (92.5%), nucleic acids were of sufficient quality for HPV‐testing. In total, 21 (2.2%) OCSCCs were HPV DNA‐positive. All HPV DNA‐positive tumors were E6 mRNA‐positive and considered as true HPV‐positive. There was no difference in survival between HPV‐positive and HPV‐negative OCSCCs. In total, 46 of 580 (7.9%) OCSCCs were p16‐immunopositive, including all HPV‐positive tumors. Survival was comparable in p16‐positive and p16‐negative OCSCCs. To conclude, HPV‐prevalence is very low in OCSCC and neither HPV‐status nor p16‐status affects outcome. Based on these data, determining HPV‐status in OCSCC seems irrelevant for clinical management. What's new? While human papillomavirus (HPV)‐infection is prognostic for oropharyngeal squamous cell carcinoma (OCSCC), its role and prognostic impact in OCSCC remain uncertain. In the present study, nucleic acid‐based HPV‐testing of a cohort of 1016 tumor samples collected from OCSCC patients diagnosed between 2008 and 2014 reveals very low HPV‐prevalence in OCSCC. In addition, no difference was found in survival between HPV‐positive and HPV‐negative tumors. The findings indicate that HPV is uncommon in OCSCC and, when present, has no impact on survival, providing new and important insight into the ongoing debate regarding the role of HPV in OCSCC. [ABSTRACT FROM AUTHOR]