Prospective study revealed prognostic significance of responses in leptomeningeal metastasis and clinical value of cerebrospinal fluid-based liquid biopsy.

•93.9% of the NSCLC-LM patient cohort carried oncogenic driver mutations.•The composite endpoint for objective response evaluation of LM was valid.•EGFR mutation testing by CSF showed high concordance with primary tumor.•EGFR T790 M occurrence in CSF was relatively rare at diagnosis of LM.