We report here a case of osimertinib used at 160 mg once daily in a heavily pretreated patient with EGFR exon 20 T790M-negative advanced NSCLC with LM to achieve a partial response, including shrinkage of the LM, for up to 12 months until further progression.
In this non-selected population, osimertinib had remarkable efficacy in NSCLC patients with LM irrespective of the presence of the EGFR-T790M-resistance mutation.
As this clinical entity is underrepresented in clinical trials, the practicability of plasma EGFR testing and the optimal dose-response relationship of osimertinib in T790M-positive lung cancer complicated with LM deserves further exploration.
In the multivariate analysis, statistically significant factors for longer PPS included T790M-positive, good performance status, and no carcinomatous meningitis.