Comparison of Standard Dose Alectinib to Alectinib in Adjusted Dose Based on Alectinib Bloodlevels

Inclusion Criteria: * Patients with locally advanced or metastatic NSCLC (stage IIIB to stage IV by AJCC 8th) * ECOG performance status 0-4 * Histologically or cytology confirmed NSCLC * Documented ALK rearrangement based on an EMA approved test * Patients can either be chemotherapy-naïve or have received one line of platinum-based chemotherapy * Patients with brain or leptomeningeal metastases are allowed on the study if the lesions are asymptomatic without neurological signs and clinically stable for at least 2 weeks without steroid treatment. Patients who do not meet these criteria are not eligible for the study * Measurable disease (by RECIST criteria version 1.1) prior to the first dose of study treatment * Signed writte Institutional Review Board (IRB)/Ethical Committee (EC) approved informed consent form, prior to performing any study-related procedures * Observational other studies are allwoed for patients included in this study * Local radiotherapy is allowed for pain Exclusion Criteria: * Any significant concomitant disease determined by the investigator to be potentially aggravated by the investigational drug * Consumption of agents which modulate CYP3A4 or agents with potential QT prolonging effects within 14 days prior to admission and during the study (see concomitant medication restrictions) * Any clinically significant concomitant disease or condition that could interfere with, or for which the treatment might interfere with, the conduct of the study, or absorption of oral medications, or that would, in the opinion of the Principal Investigator, pose an unacceptable risk to the subject in this study. * Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol requirements and/or follow-up procedures; those conditions should be discussed with the patient before trial entry.