ALK and non-small cell lung carcinoma: However, a more pronounced CNS prevention/delay effect was observed in ALK inhibitor-naive, front-line ALK-positive NSCLC patients as studied in ALEX; at 24 months, 16.0 and 4.6% of patients with or without CNS metastases at baseline, respectively, had CNS progression in ALEX, whereas 43.9 and 8% of patients had CNS PD in the phase II studies.