...cohort 1, LM patients were treated with osimertinib with CSF and plasma genotyping performed before the first dosing of osimertinib (baseline, n=45);...Concurrent CDK4 (2.8 versus 11.6 months, P=0.002) and CDKN2A (2.5 versus 9.6 month, P=0.04) mutation with EGFR sensitizing mutations indicated lower median iPFS.