Figure 4c:

Images in 77-year-old woman with anaplastic lymphoma kinase (ALK)-rearranged advanced non–small cell lung cancer who developed acquired resistance to crizotinib and subsequently responded to alectinib. (a) Baseline CT image obtained prior to crizotinib therapy shows a dominant mass in the left lower lobe (arrow) and multiple lung nodules. (b) Follow-up CT image obtained after 5 months of crizotinib therapy shows marked response to therapy, with a clinically significant reduction of the dominant lung mass (arrow) and lung nodules. However, the mass (arrow) started to grow back over the course of treatment, as noted on (c) a follow-up CT image obtained after 17 months of crizotinib therapy, indicating the development of acquired resistance to crizotinib. Crizotinib therapy was stopped, and the patient was treated with alectinib. On (d) follow-up CT image obtained after 2 months of alectinib therapy, the recurrent tumor responded to therapy (arrow).