Lung cancer is the most common cause of cancer mortality in the UK, accounting for more than one in five cancer deaths (Cancer Research UK 2016). Within that number, 85-90% of cases are non-small cell lung cancer (NSCLC) (Reck et al 2014) and, in around 5% of those cases, patients are found to carry a translocation in the anaplastic lymphoma kinase (ALK) gene (Shaw et al 2014). Patients who test positive for this translocation (ALK+) can be treated with ALK inhibitors. While the first-generation ALK inhibitor crizotinib may be effective initially, many patients with advanced ALK+ NSCLC develop resistance and experience disease progression during treatment (Shaw et al 2014).