Mechanisms of Resistance to Amivantamab in Patients With NSCLC With EGFR Exon 20 Insertion

This study investigates why some lung cancers stop responding to a drug called amivantamab. It focuses on patients with non-small cell lung cancer (NSCLC) who have a specific genetic change called an EGFR exon 20 insertion. Researchers will collect blood and tissue samples to understand how the cancer develops resistance. **You may be eligible if...** - You are 18 or older - You have advanced non-small cell lung cancer with the EGFR exon 20 insertion mutation - You are currently receiving amivantamab as a single treatment (not combined with other drugs) in France - Your cancer has progressed while on amivantamab - You are enrolled in the French national health insurance program **You may NOT be eligible if...** - You are receiving amivantamab combined with another treatment - You are not willing to provide blood samples - You are not in France's healthcare system Talk to your doctor to see if this trial is right for you.