Phase 2 study of subjects with ALK positive, advanced NSCLC who have failed up to 3 prior therapies. The study will take place globally at multiple study centers. Subjects will be enrolled to receive ganetespib one time per week for three weeks followed by a rest week; and will repeat this schedule until the cancer gets worse or the subject is unable to tolerate ganetespib. The primary goal of the study is to determine how ganetespib is tolerated and how active it is in ALK positive NSCLC.