Prospective Study for the Prognostic and Predictive Role of Circulating Tumor Cells in Patients With Oropharyngeal Squamous Cell Carcinoma: CTCO (Circulating Tumor Cells in the Oropharynx)

Head and neck cancers (HNSCC) are primarily squamous cell cancers represented by tumors of the upper aerodigestive tract. Locally advanced stages (stages III and IV) account for 50 to 70% of all presentations. The three main risk factors are smoking, alcohol and oropharyngeal infection with human papilloma virus (HPV).

Apart from HPV status, there is no biomarker for the prognosis in HSNCC patients. Circulating Tumor Cells (CTCs) can provide "real-time" information on tumor behavior and are already used in various cancers (colon, lung). Their detection has limited sensitivity and biomarkers cannot be used for early diagnosis, but may be useful during follow-up to assess local, regional or metastatic early tumor recurrence.

By using blood samples at different times (at diagnosis, after initial treatment and during follow-up), we will be able to measure the variation in quantification and establish a predictive role of these CTCs for the response to treatment.

Our hypothesis is that CTCs may have a key role, in addition to clinical and radiological examination, in detecting early tumor relapse.

We believe that the joint consideration of clinical parameters, treatment strategy and quantification of CTCs could optimize patient follow-up and management.

The CTC extraction system, ClearCell® FX from Biolidics, is an automated microfluidic enrichment system. It has the advantage of recovering fully intact and viable CTCs from a standard blood sample. The gentle sorting principle allows to preserve cell integrity and thus the expression of surface antigens. The CTCs thus isolated can then be re-cultured or analyzed by immunostaining. This high-performance technique, in operation since December 2017 in the Biochemistry Department of Pr Claire Rodriguez-Lafrasse (HCL), has demonstrated its usefulness in lung cancer.

Transcriptomic analysis of CTCs can be performed at the scale of a cell after isolation of the CTCs. CTCs can then be sequenced in RNAseq either in bulk (pool of cells) or cell by cell on our Illumina (Nextseq) sequencer, in order to define the heterogeneity of the tumor. Transcriptome analysis then provides information on the state of the cell as to its position in the epithelio-mesenchymal transition thanks to a molecular signature by phenotype. A priori-free characterization is therefore possible thanks to the RNAseq single-cell. This highly sensitive and innovative technique will allow the study of the gene expression profile of CTCs.