Abstract
Specific tyrosine-kinase inhibitors (TKIs) are widely used for the treatment of non-small-cell lung cancers with anaplastic lymphoma kinase (ALK) translocations. However, most treated patients eventually develop resistance to the TKIs. The histological transformation into small cell carcinoma is well known to be the underlying mechanism for acquired resistance; however, transformation to squamous cell carcinoma is extremely rare. We, herein, report a case of ALK rearrangement-positive adenocarcinoma that transformed to squamous cell carcinoma after administration of alectinib, and was found to be resistant to ceritinib.