Activation of the EGFR pathway is one of the mechanisms inducing acquired 
resistance to anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKI) 
such as crizotinib and alectinib. Ceritinib is a highly selective ALK inhibitor 
and shows promising efficacy in non-small cell lung cancers (NSCLC) harboring 
the ALK gene rearrangement. However, the precise mechanism underlying acquired 
resistance to ceritinib is not well-defined. This study set out to clarify the 
mechanism in ALK-translocated lung cancer and to find the preclinical rationale 
overcoming EGFR pathway-induced acquired resistance to ALK-TKIs. To this end, 
ceritinib-resistant cells (H3122-CER) were established from the H3122 NSCLC cell 
line harboring the ALK gene rearrangement via long-term exposure to ceritinib. 
H3122-CER cells acquired resistance to ceritinib through EGFR bypass pathway 
activation. Furthermore, H3122 cells that became resistant to ceritinib or 
alectinib through EGFR pathway activation showed cross-resistance to other 
ALK-TKIs. Ceritinib and afatinib combination treatment partially restored the 
sensitivity to ceritinib.
IMPLICATIONS: This study proposes a preclinical rationale to use ALK-TKIs and 
afatinib combination therapy for ALK-translocated lung cancers that have 
acquired resistance to ALK-TKIs through EGFR pathway activation. Mol Cancer Res; 
15(1); 106-14. ©2016 AACR.