Study of FIH of STX-241 in Locally Advanced or Metastatic NSCLC Resistant to EGFR TKIs

This study is testing STX-241 — a new targeted drug — in patients with advanced non-small cell lung cancer (NSCLC) whose tumors have an EGFR mutation and have developed a specific resistance mutation (C797X) after treatment with third-generation EGFR-blocking drugs. This resistance mutation is a common reason why these lung cancers eventually stop responding to targeted therapy. **You may be eligible if...** - You are 18 or older with confirmed advanced NSCLC (stage IIIB/C or IV) with an EGFR exon 19 deletion or L858R mutation - Your cancer has progressed on a third-generation EGFR inhibitor (like osimertinib) - A blood or tissue test after progression shows the C797X resistance mutation, and does NOT show T790M - You have measurable disease on imaging - You are in good general health (ECOG 0–1) - Your heart, blood, liver, and kidney function are adequate **You may NOT be eligible if...** - Your tumor does not carry the C797X resistance mutation - You are pregnant or breastfeeding - You have serious heart rhythm problems or poor heart function - You have active, uncontrolled infections or autoimmune disease - You have brain metastases that are not stable Talk to your doctor to see if this trial is right for you.