Anaplastic lymphoma kinase (ALK) rearrangement lung cancer responds to ALK 
tyrosine kinase inhibitors. It is known that many cases ultimately acquired 
resistance to crizotinib. However, a case of primary resistance is rare. We 
present a case of harboring exon 19 deletion in epidermal growth factor receptor 
in ALK rearranged lung adenocarcinoma, who experienced a partial tumor response 
to icotinib after failure with crizotinib therapy and chemotherapy. Considering 
the partial response, we conclude that it is important to find the cause of 
resistance to crizotinib. We detected gene mutations with plasma by the 
next-generation sequencing; the next-generation sequencing demonstrates an 
attractive system to identify mutations improving the outcome of patients with a 
deadly disease.