Acquired L718V/ co-mutation and discordant molecular pattern between plasmatic and cerebrospinal fluid in a bone and meningeal metastatic L858R+ non-small cell lung cancer: a case report.

Background: Osimertinib is approved in first line metastatic epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer (NSCLC). Acquired L718V mutation is a rare mechanism of resistance towards osimertinib in L858R+ NSCLC with potential sensibility to afatinib. This case reported an acquired L718V/TP53 V727M resistance co-mutation to osimertinib with discordant molecular pattern between plasmatic and cerebral fluid in a leptomeningeal and bone metastatic L858R mutant NSCLC.