Expression of receptor tyrosine kinases in esophageal carcinosarcoma

Esophageal carcinosarcoma (ECS) is a rare malignant neoplasm associated with a poor patient prognosis. It is characterized by the presence of both malignant epithelial and mesenchymal components. Molecular-targeted therapy of several receptor tyrosine kinases (RTKs) has been reported to be effective in the treatment of various malignant tumors, including carcinosarcoma of several organs. This study aimed to assess the therapeutic potential of targeting RTKs in ECS. Overexpression of RTKs was assessed in 21 ECS cases by immunohistochemistry (IHC). Positively stained cases were further examined for RTK gene mutations and amplifications by direct sequencing analysis and fluorescence in situ hybridization. In epithelial components, KIT, platelet-derived growth factor receptor (PDGFR)A, PDGFRB, MET, epidermal growth factor receptor (EGFR) and HER-2 were overexpressed in 1 (4.8%), 1 (4.8%), 0 (0%), 11 (52.4%), 13 (61.9%) and 2 (9.5%) cases, respectively. In the mesenchymal components the corresponding numbers of cases were 2 (9.5%), 2 (9.5%), 0 (0%), 12 (57.1%), 11 (52.4%) and 0 (0%). No mutations in the c-kit, PDGFRA and c-met genes were found. Among 19 EGFR-positive tumors, 2 had EGFR missense mutations (T790A, exon 20) only in the mesenchymal component. Gene amplification or high polysomy of c-kit, PDGFRA, c-met and EGFR was observed in 1 (33.3%), 0 (0%), 3 (18.8%) and 10 (52.6%) cases, respectively. In conclusion, various RTKs, particularly MET and EGFR were overexpressed in ECSs suggesting that molecular-targeted therapies directed to MET, EGFR or other RTKs may be effective in inhibiting the growth or progression of the epithelial and/or mesenchymal component of ECS.