Abstract 2102A: Simultaneous targeting of EGFR and ALK in EML4-ALK positive lung cancer to inhibit tumor cell proliferation and migration

Approximately 4-7% of non-small cell lung cancers (NSCLC) harbor the EML4-ALK chromosomal rearrangement. ALK has been identified as a molecular driver of cancer and ALK inhibitors have been developed for clinical use. We have confirmed high expression of EGFR in EML4-ALK-positive cell lines (H3122 and H2228). Recognizing the capacity of both EGFR and ALK signaling to regulate tumor cell growth, we investigated the effects of co-inhibition of ALK and EGFR on cell proliferation and migration in EML4-ALK-positive cells in vitro. We also examined the anti-tumor effect of ALK and EGFR inhibitors in xenograft mouse models. Cell proliferation was determined by CCK8 and cell migration was examined by wound healing assay and transwell migration assay. ALK inhibitors (crizotinb, ceritifinib and alectinib) and EGFR inhibitors (erlotinib and gefitinib) were utilized to block ALK and EGFR signaling activity. We confirmed that H3122 and H2228 cells were resistant to EGFR inhibitors in comparison to EML4-ALK negative cell lines H226 and A549. Simultaneous knockdown of ALK and EGFR by siRNA significantly inhibited tumor cell proliferation. Combined inhibition of ALK and EGFR inhibited cell proliferation more potently than single inhibitor treatment alone. In addition, NIH3T3 cells expressing EML4-ALK variants 1, 2 or 3a displayed enhanced ability for cell migration, suggesting a role of EML4-ALK in cell migration. Individual ALK inhibitors and EGFR inhibitors inhibited cell migration. Further, combined ALK and EGFR blockade resulted in a stronger cell migration inhibition than single agent therapy. The combination of ALK inhibitor with EGFR inhibitor was more potent than single target treatment in tumor xenograft growth inhibition. Mechanistic analysis of the co-regulation of cell migration by ALK and EGFR signaling in EML4-ALK positive cells is under investigation. These results identify enhanced inhibitory effects on tumor cell proliferation and migration with simultaneous blockade of ALK and EGFR signaling suggesting that dual targeting may prove more effective than single agent approaches. These findings indicate the potential for therapeutic benefit of co-targeting ALK and EGFR in patients with EML4-ALK positive NSCLC. Citation Format: Chunrong Li, Joseph G. Kern, Shyhmin Huang, Eric A. Armstrong, Lauryn R. Werner, Paul M. Harari. Simultaneous targeting of EGFR and ALK in EML4-ALK positive lung cancer to inhibit tumor cell proliferation and migration. [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 2102A.