Patients with EGFR-mutated non-small-cell lung cancer who have progressed after first-line therapy with afatinib and participate in the AIO-TRK-0114 (MARBLE) study (EudraCT-No. 2014-001983-36) are offered participation in Trans-MARBLE. If written informed consent is granted, archival surplus diagnostic tumor samples, blood samples and fresh tumor samples are acquired during medically indicated diagnostic procedures.