[Genomic alterations in thymic epithelial tumors: State of knowledge, and the interest of liquid biopsy]

In the absence of randomized phase III trial data, thymic epithelial tumors (TETs) are rare malignancies of the prevascular mediastinum managed according to the WHO histological and the Masaoka-Koga classifications.

Next-generation sequencing has revealed distinct mutational characteristics between thymomas, which are characterized by a low tumor mutational burden and a near-specific GTF2I mutation, and thymic carcinomas which are dominated by alterations in CDKN2A, TP53 and KIT. These findings open the way for novel therapeutic strategies, involving immune checkpoint inhibitors and multi-kinase inhibitors in advanced thymic carcinomas. Notwithstanding the potential of liquid biopsy as a non-invasive monitoring tool, specific biological obstacles in TETs currently limit its clinical applicability.

Recent confirmation of the interest of liquid biopsy in perioperative management of lung cancer raises the prospect of transferring this approach to TETs. The key challenge lies in identifying the biological marker most suited to the monitoring of longitudinal tumors.

Genomic profiling of TETs enhances (rather than supplants) the historical histological classification, and should progressively inform therapeutic stratification, particularly in cases of thymic carcinoma.