Have a patient with metastatic lung adenocarcinoma (EGFR exon 19 del) who is now progressing radiographically with new adrenal met. Liquid NGS shows an EGFR C797N mutation. In review of literature it is not clear if this is an acquired osimertinib resistance mutation (like C797S). Would you switch therapy at this time? PS is 0 and patient has no comorbities
Thanks for the interesting question. I do not think there is a clear cut answer. if the adrenal is the only location you could use SBRT and keep the osi going though likely there will be (potentially slow) progression based on your liquid NGS findings. if you choose to use a first generation TKI like gefitinib or erlotinib then I would also keep the osimertinib going. If you cannot get approval for it, industry might offer patient assistance. I think the SBRT could buy you some more time, though if she feels well on the osi currently. Hopefully we will see some results with this co-mutation from the ORCHARD trial arm adding gefitinib to osimertinib soon.
