The VEGF-system in primary pulmonary angiosarcomas and haemangioendotheliomas: New potential therapeutic targets?

Malignant epitheloid vascular tumors (epitheloid haemangioendotheliomas and angiosarcomas) of the lung are very rare lesions often posing difficulties in diagnosis. Due to their rare incidence no standardized therapy regimen is established. Surgical resection of the tumor is the mainstay of treatment, but in many cases, especially due to the multifocality of the tumor, negative resection margins cannot be achieved. A blockade of members of the vascular endothelial growth factor (VEGF) system either by antibodies for their ligands or by kinase inhibitors has been increasingly used for the therapy of solid tumors. The aim of our study was to highlight the main distinguishing morphological factors between the two entities for diagnostic purposes. Next, we investigated several factors of the VEGF-signalling pathway as well as Tie 2 in eight primary pulmonary epitheloid haemangioendotheliomas and ten primary pulmonary epitheloid angiosarcomas by means of immunohistochemistry using commercially available antibodies against VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGFR-2, VEGFR-3 and endothelium specific kinase Tie2. The observed positivity for the factors of the VEGF-signalling pathway points towards a possible new therapeutic option in the therapy of pulmonary vascular tumors by a blockade of the ligands or their receptors.