Detection of Resistance Mechanisms in Cerebrospinal Fluid for EGFR-mutant, ALK- and ROS1-rearranged

To determine the detection rate of driver oncogenes and resistance mechanisms in cerebrospinal fluid (CSF) for patients with CNS progression (with or without extra-CNS (eCNS) progression) and concordance with plasma/tissue * For each individual patient with CNS progression (with or without eCNS progression), compare the molecular status (primary oncogene detection and any mechanisms of identifiable resistance including EGFR-, ALK- and ROS1-mutations, ALK-amplification and bypass-tracks activating mutations) of CSF, plasma and CNS tissue (if data from pathology report is available) * Molecular status will also be compared with previously obtained and stored plasma/tissue prior to the initiation of current next-generation tyrosine-kinase inhibitor (TKI)