6078 Background: Squamous cell carcinoma of the head and neck (SCCHN) is still an incurable disease in the metastatic setting. A particular subgroup of proteins implicated in the head and neck cancer are the tyrosine kinases (TK). Therapeutic inhibition of several of them including the EGF receptor with cetuximab in combination with radiotherapy or chemotherapy has shown to be clinically useful. Beyond EGFR, oncogenic activation of other TKs may be implicated in the genesis/progression of SCCHN. In this context, the identification of the TKs activated in SCCHN is a must in order to adequately target these kinases with already available inhibitors. Methods: Here we have investigated activated tyrosine kinases in head and neck cancer tumors derived from patients using a human phospho protein array for 42 receptor tyrosine kinases (RTK). Western-blot experiments were performed to validate each phospho RTK in tumors from patients. The same approach was followed in a series of head and neck cancer cell lines. In vivo xenografted models were used to study the antiproliferative effect of the combination of specific TK inhibitors against them. Results: TK receptors of the EGF and the VEGF family were the mostly activated in tumors derived from patients. 90% of patients revealed high pEGFR content. In addition, other EGFR/HER family receptors, such as HER3, were also activated (phosphorylated) in samples from patients. These data were corroborated in the SCCHN cell lines. In these cells, other RTK signalling intermediates were also active. Particularly, the Akt and FAK kinases. Combination of the anti-EGFR-HER2 TK inhibitor lapatinib with dasatinib (that targets FAK) was synergistic in vitro. Combination of lapatinib with the anti-VEGFR TK inhibitor pazopanib was inefficient in vitro, but resulted in a better trend in response in the in vivo xenografted models, as compared to the action of the single agents. Conclusions: Rational target drug combinations should be based on the identification of activated TK receptors or downstream signalling molecules. In head and neck cancer combination strategies using anti-EGFR/HER, anti-FAK, and anti-VEGFR compounds increases the action of individual treatments. These results open the door for future clinical development of these drug combinations. No significant financial relationships to disclose.
Head and neck cancer organoids established by modification of the CTOS method can be used to predict in vivo drug sensitivity
