@lmd1, This news has to be so hard to hear. Deflating. Sorry, I'm not on Tagrisso, but I do take a different targeted therapy, that will eventually stop working for me too. It sounds like your oncologist is taking the appropriate steps in ordering a fresh biopsy and biomarker test, to see if there is a different therapy that may help. Do you have progression in just one area, or multiple areas? The Tagrisso may still be protecting other parts of your body, are you continuing to take it?