Primary and secondary resistance to tyrosine kinase inhibitors in lung cancer.

BACKGROUND Tyrosine kinase inhibitors (TKI) have emerged as important therapeutic agents for the treatment of several types of cancer including lung cancer. Recent research attempts show that only a small population of cancer patients responds to TKI and furthermore, these patients eventually develop resistance. Studies support the classification of resistance in primary and secondary resistance. MATERIALS AND METHODS In the present study the differentiation between primary and secondary resistance to TKI in lung cancer cell lines was investigated. Lung cancer cell lines were tested for viability, apoptosis and cell cycle after exposure to the TKI erlotinib and gefitinib. RESULTS Cells with primary resistance showed similar cell-cycle patterns to those with secondary resistance but differences were observed between the two groups in the viability and apoptosis assays. CONCLUSION Understanding the effects of TKI on cell signaling pathways would shed light on the mechanisms of acquired resistance and the differences between primary and secondary resistance.