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

This study compares two approaches to dosing alectinib, a targeted therapy pill, in people with advanced non-small cell lung cancer (NSCLC) that has a specific genetic change called an ALK rearrangement. One group receives the standard dose; the other receives a dose adjusted based on blood levels of the drug. **You may be eligible if...** - You have locally advanced or metastatic NSCLC (stage IIIB–IV) confirmed by tissue or cell testing - Your tumor has a confirmed ALK rearrangement - You have either not yet had chemotherapy or have received one round of platinum-based chemotherapy - You have measurable disease on imaging scans - You have brain or leptomeningeal metastases that are stable and not causing symptoms **You may NOT be eligible if...** - You are currently taking medications that significantly affect how the liver processes drugs (CYP3A4 inhibitors/inducers) or drugs that can prolong the heart's electrical activity - You have another serious medical condition that the investigator believes would be worsened by alectinib Talk to your doctor to see if this trial is right for you.