Thymic epithelial tumors express vascular endothelial growth factors and their receptors as potential targets of antiangiogenic therapy: A tissue micro array-based multicenter study.

Objectives: Tumor angiogenesis is an essential and complex process necessary for the growth of all tumors which represents a potential therapeutic target. Angiogenesis inhibitors targeting vascular endothelial growth factor (VEGF) or their receptor tyrosine kinases have been approved by the FDA. In thymic epithelial tumors (TET), targeted therapies have been sporadically applied due to their rarity. To ascertain the presence of potential therapeutic targets, we analyzed by immunohistochemistry the expression of angiogenesis-related biomarkers in a large series of TET arranged in Tissue Micro Arrays (TMA). Materials and methods: We assessed by immunohistochemistry the expression of the possible molecular target of anti-angiogenic therapy, i.e. VEGFA, VEGFC, VEGFD, VEGFR1, VEGFR2, VEGFR3, and PDGFR beta, in a TMA series of 200 TET collected in the framework of a multi-institutional collaborative project for Rare Diseases. Results: When compared to the low-risk tumors, high-risk TET (B2, B3, carcinomas) contained higher proportion of cancer cells expressing VEGFA, VEGFC and VEGFD (P < 0.001, P < 0.001, and P < 0.001) growth factors, and their receptors VEGFR1 (P = 0.002), VEGFR2 (P = 0.013), and VEGFR3 (P = 0.041). No differences were observed in terms of PDGFR beta expression. Conclusions: According to our data, it is possible to hypothesize the existence of multiple paracrine and/or autocrine loops in TET, particularly in the high-risk ones, involved in TET growth and progression. Antiangiogenic agents, directed to inhibit these loops, are therefore to be considered as potential tools in advanced TET therapy.