Abstract 2121: Src mediates acquired resistance to ALK inhibitor in ALK-rearranged non-small cell lung cancers

ALK tyrosine kinase inhibitors (TKIs) play a significant role in the treatment of ALK-rearranged non-small cell lung cancer patients.After the significant initial response to ALK-TKIs, the emergence of acquired resistance ultimately occur for all patients. Understanding the origin of resistance mechanisms within a patient is crucial to guide treatment and developing drugs/combinations to circumvent resistance. There are reported that some of the tyrosine kinases are involving by bypassing ALK signaling, but comprehensive identification of proteins that are significant for acquired resistance in ALK-TKIs is still required. Quantitative proteomic analysis provides a powerful approach in screening for alterations in protein levels. An analysis of the differential proteins expression between original cancer cell and acquired resistance cell would be useful for identification of proteins drug resistance. To investigate the changes of chaperon holding proteins, ALK rearranged-cell line H3122 were used. ALK-TKI Alectinib resistant cell lines were established by exposing increased dose of alectinib to ALK rearranged H3122 cell line (AFR). Luminespib (AUY922, Novartis Pharm.) was used as HSP90 inhibitor and Saracatinib (Selleck Chemicals.) was used as Src inhibitor in this study. We used iTRAQ (isobaric tags for relative and absolute quantitation) technology using nano-LC-MS/MS analysis, to identify alterations in H3122 protein levels of pre/post HSP90 inhibitor treatment. For further analysis, protein expression was measured by western blot. To assess the cancer cell growth inhibition for ALK and/or Src inhibitors, we used colony formation assay. Our results revealed that Crk-Src related proteins were overexpressed in ALK TKI resistance cells and had a significant protein expression changes after HSP90 inhibitor treatment. To address the impact of overcoming resistance by blocking Crk-Src pathway, Drugs/combinations with ALK inhibitor and/or Src inhibitors showed that significant treatment effect in vitro and in vivo study using tumor-bearing mouse model. Conclusion Src is one of the significant signaling pathways in the ALK-rearranged NSCLCs resistant to ALK-TKIs including alectinib, and inhibiting Src signaling could be a potential target for ALK-rearranged NSCLC after ALK-TKI resistance. Citation Format: Ryohei Yoshida, Shunsuke Okumura, Takaaki Sasaki, Yoshinobu Osaki. Src mediates acquired resistance to ALK inhibitor in ALK-rearranged non-small cell lung cancers. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2121.