Epidermoid Carcinoma of the Upper Aerodigestive Tract (CEVADS) is the 6th most common cancer worldwide. Despite current therapies (radiotherapy, surgery and chemotherapy), cancers of the Upper Aerodigestive Tract (UAT) have a poor prognosis, with a 10-year survival rate of no more than 20%.
For recurrent or metastatic CEVADS, the therapeutic arsenal, based for many years on chemotherapy and anti-EGFR (Epidermal Growth Factor Receptor) agents, has been enriched by a new therapeutic class: PD-1 inhibitors. For CEVADS, PD-1 inhibitors have been approved for second-line treatment of nivolumab for over a year, and are now used in first-line treatment of pembrolizumab.
The results of this therapeutic class in CEVADS are not as spectacular as for melanoma or bronchial cancer. Indeed, only 20% of patients have a favorable response, compared with half who experience disease progression. This low proportion of responders can be explained by tumor heterogeneity within CEVADS and poor patient selection.
The only marker used to select patients is PD-L1 expression detected by ImmunoHistochemistry (IHC). However, it seems that this marker, described as imperfect, is still little explored in ENT. It needs to be compared with the expression of other cell lines in the tumor microenvironment, which could play an important role in resistance to PD-1 inhibitors.
IHC identifies all macrophages using the CD68 marker, while the CD163 marker is specific to M2 macrophages.
Other targets in the microenvironment are also being investigated, with the discovery of a Tertiary Lymphocyte Structure (TLS) in melanoma treated with immunotherapy.
It therefore seems necessary to gain a better understanding of the mechanisms of tumor progression under immunotherapy in order to develop strategies to optimize response to treatment. This would enable better selection of patients likely to benefit from immunotherapy, and open up prospects for therapeutic combinations.
The hypothesis is that macrophages, but also other cells and factors in the CEVADS microenvironment, play a decisive role in resistance to PD-1 inhibitors. The aim is therefore to continue these macrophage analyses, extend them to other cells in the microenvironment and link them to other prognostic factors under investigation.
A prospective study will analyze tumor tissue during treatment with PD-1 inhibitors, in order to correlate all the factors studied with response or resistance to immunotherapies.
In addition, the oral microbiota, in the lineage of the intestinal microbiota, has been shown to be highly stable over time and to play a role in the oncogenesis of certain cancers, notably CEVADS. Like the intestinal microbiota, it could also represent a prognostic factor in the response to immunotherapies.
Of all the bacteria in this oral microbiota, one has been shown to play a major role: Fusobacterium nucleatum (F. nucleatum). However, little is known about the mechanism of action of intratumoral F. nucleatum on the development of CEVADS. In particular, it is thought to play a role in local cancer immunity, via macrophages, regulatory T cells (Tregs) and TLRs. Finally, it appears that specific antimicrobial T-cell responses may cross-react with tumor antigens, hence the importance of also analyzing the metabolome of commensal bacteria.The aim of this study was to evaluate the evolution of the presence of this bacterium in saliva, as well as the specific immune response to F. nucleatum in patients with CEVADS during immunotherapy treatment.