CNSC-04. CEREBROSPINAL FLUID-DERIVED CIRCULATING TUMOR DNA IS SUPERIOR TO PLASMA IN NSCLC PATIENTS WITH CNS PROGRESSION

Abstract Introduction Central nervous system (CNS) metastases are devastating neurologic complications. However, the clinical value of cerebrospinal fluid (CSF) as liquid biopsy medium in EGFR-mutated or ALK-rearranged patients with brain (BM) leptomeningeal (LM) remains unclear. Patients and Methods We retrospectively analyzed gene map 14/48 NSCLC-BM 34/48 NSCLC-LM patients. Compare predictive CSF matched plasma (PLA) for single CNS progression (cohort 1) intracranial simultaneously extracranial disease 2). Circulating cell-free tumor DNA (ctDNA) PLA underwent next-generation sequencing targeting 168 cancer-relevant genes. Results For progression, mutation rate major driver genes is much higher than PLA. Besides, also demonstrated levels potential prognostic markers comparison samples, showing EGFR-amp presented more two times compared to PLA, detection TBX3, PTEN were almost double paired samples. In addition, poor outcomes associated makers including CDKN2A/B, PIK3CA/G, CDK4/6, MET showed exclusively samples.Almost all mutations identified could detect samples both progression. rates mutations, consisting EGFR ALK these survival marker like EGFR-amp, MET, PIK3CA uniquely Conclusion comprehensive genomic profile NSCLC -LM regardless evolution.