ALK inhibitors are potential anti-cancer drugs that act on tumours with variations of anaplastic lymphoma kinase (ALK) such as an EML4-ALK translocation. ALK inhibitors are potential anti-cancer drugs that act on tumours with variations of anaplastic lymphoma kinase (ALK) such as an EML4-ALK translocation. About 4-7% of non-small cell lung carcinomas (NSCLC) have EML4-ALK translocations.