Osimertinib as Salvage Therapy in Advanced Non‐Small Cell Lung Cancer After Aumolertinib Resistance With <scp>T790M</scp> Mutation: A Case Report

The third generation of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is recommended universally as the standard treatment for non-small cell lung cancer (NSCLC) carrying the <i>EGFR</i> T790M mutation. With the approval of multiple third-generation EGFR-TKIs, questions have arisen regarding the differences in their efficacy and how to select the most appropriate agent for individual patients. The study reports a case of an advanced NSCLC patient with multiple brain metastases. The patient initially received the pemetrexed plus carboplatin (PC) regimen for 5 months and displayed stable disease. Upon disease progression, the patient was treated with aumolertinib as second-line treatment due to the detection of <i>EGFR</i> L858R and T790M mutations, but the symptoms of brain metastases deteriorated. Switching to osimertinib successfully relieved the patient's symptoms and achieved a long progression-free survival (PFS) of nearly 2 years. Leptomeningeal metastasis was then definitively diagnosed, and the patient eventually died approximately 4 months after osimertinib resistance. This case suggests that osimertinib may be a viable option for <i>EGFR</i>-mutant NSCLC patients after aumolertinib failure, especially for those with intracranial metastases.