Cilengitide and Cetuximab Reduce Cytokine Production and Colony Formation of Head and Neck Squamous Cell Carcinoma Cells Ex Vivo.

BACKGROUND/AIM: To analyze ex vivo effects of combined targeting of the epidermal growth factor-receptor (EGFR) by cetuximab (E) plus αVβ3 and αVβ5 integrins by cilengitide (Cil) on colony formation of epithelial cells (CFec) and release of pro-angiogenetic and pro-inflammatory cytokines in head and neck squamous cell carcinoma (HNSCC) cells.

MATERIALS AND METHODS: Collagenase-IV digests of 43 histopathological confirmed HNSCC cases were seeded into laminin-coated 96-well plates containing E, Cil, or Cil+E in final concentrations of 66.7 μg/ml, 10 μM, and 10 μM+66.7 μg/ml, respectively. Following the FLAVINO-assay protocol, supernatants were harvested after 3 days and adherent cells fixed in ethanol. Counting of CFec was facilitated by FITC-labeled pan-cytokeratin antibodies. Out of 43 HNSCC cases, 39 had adherent growth (mean CFec≥4/well in triplicate controls). Cytokines in supernatants were measured using ELISA were interleukin 6 (IL-6), monocyte chemoattractant protein 1 (MCP-1) and vascular endothelial growth factor A (VEGFA).

RESULTS: CFec on laminin was significantly reduced by Cil, E, and Cil+E. Cytokine measurements also revealed significant suppression of MCP-1, IL-6 and VEGFA. The strongest suppression of CFec, MCP-1 and VEGFA release was exerted by Cil and E combined. Efficacy of Cil+E exceeded those of the solely applied pharmaceutics but failed regarding significant synergism of both treatments as E was unable to significantly boost the effects of Cil. In contrast, IL-6 release was significantly suppressed by E but not by Cil, while their combination strongly reduced it.

CONCLUSION: Combined targeting of EGFR and integrins with E and Cil heightens their suppressive effects regarding CFec as well as release of pro-angiogenetic and pro-inflammatory cytokines.