Tracey L. Evans, MD of the University of Pennsylvania describes what determines using osimertinib in first line treatment.
Dr. Evans had two patients newly diagnosed after the FLAURA results came and both of them were given osimertinib in first line. One of them was given afatinib at first, but had toxicity, which justified immediate shift to osimertinib. And, because the FLAURA data is very impressive, she is convinced to use osimertinib in the first line. However, its still not FDA approved.
So, for those patients who are already on the earlier generation of the EGFR TKI, like the erlotinib or afatinib, Dr. Evans are not switching them over to osimertinib just because of the FLAURA data. Progression is very important to decide the switch. Doctors can do mutation testing to determine if they have mutations that will not respond to osimertinib or what their resistance mechanism is. Another thing to keep in mind is that, there is a small percentage of patients who develop small-cell transformation on their EGFR TKI therapy. This is another reason to do biopsy. Biopsy at progression can guide doctors and other health practitioners on their next step.