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MA16 - Novel Mechanisms for Molecular Profiling (ID 917)
- Event: WCLC 2018
- Type: Mini Oral Abstract Session
- Track: Advanced NSCLC
- Presentations: 1
- Coordinates: 9/25/2018, 13:30 - 15:00, Room 203 BD
MA16.10 - Clinical Utility of Cerebrospinal Fluid Cell-Free DNA for Clarifying Genetic Features of Leptomeningeal Metastases in ALK Rearrangement NSCLC (ID 12142)
14:35 - 14:40 | Presenting Author(s): Meimei Zheng
Leptomeningeal metastases (LM) were associated with a poor prognosis in non small cell lung cancer (NSCLC). LM were much more frequent in EGFR mutant patients, and cerebrospinal fluid (CSF) cell-free DNA (cfDNA) has shown unique genetic profiles of LM in patients harboring EGFR mutations in our previous studies. However, studies in ALK positive NSCLC patients with LM are scarce.a9ded1e5ce5d75814730bb4caaf49419 Method
Lung cancer patients with ALK rearrangement were screened from Sept 2011 to Feb 2018 at our institute. Leptomeningeal metastases were diagnosed by MRI or CSF cytology or next-generation sequencing (NGS) of CSF cfDNAs. Paired plasma were also tested by NGS.4c3880bb027f159e801041b1021e88e8 Result
LM were diagnosed in 22 (7.6%) of 288 ALK rearrangement patients with lung cancer. A total of 11 ALK positive patients with LM were enrolled with CSF cfDNA tested by NGS (one case used CSF precipitates instead of CSF cfDNA). Paired plasma were available in 11 patients. Driver genes were detected in 75.0% CSF samples and 45.5% plasma respectively (P＝0.214). Max allele fractions were higher in CSF cfDNA than in plasma (40.8% versus 0%, P＝0.021). ALK variant 1 (E13:A20) was detected in 3 cases of CSF and paired plasma, respectively. ALK variant 2 (E20:A20) was identified in 5 cases of CSF and 1 paired plasma. Multiple copy number variants (CNV) were mainly found in CSF cfDNA, including EGFR copy number gains. Resistance mutations including gatekeeper gene ALK G1202R was identified in CSF cfDNA with ALK variant 1 and ALK G1269A was detected in plasma. The detection rate of TP53 was 45.4% versus 27.3% in CSF cfDNA and plasma.
CSF cfDNA was more sensitive than plasma to reveal genetic features of ALK-fusion LM, confirming its role as a liquid biopsy medium for LM in driver gene positive NSCLC.6f8b794f3246b0c1e1780bb4d4d5dc53
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P1.01 - Advanced NSCLC (Not CME Accredited Session) (ID 933)
- Event: WCLC 2018
- Type: Poster Viewing in the Exhibit Hall
- Presentations: 1
- Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
P1.01-55 - Unique Genetic Profiles from Cerebrospinal Fluid Could Predict Survival of EGFR-Mutant NSCLC with Leptomeningeal Metastases (ID 12369)
16:45 - 18:00 | Author(s): Meimei Zheng
Leptomeningeal metastases (LM) are more frequent in NSCLC with EGFR mutations；and cerebrospinal fluid (CSF) could reveal the unique genetic profiles of LM in our previous studies, but whether they could predict the overall survival (OS) of LM remains unknown.a9ded1e5ce5d75814730bb4caaf49419 Method
EGFR-mutant NSCLC patients with LM were enrolled，and clinical data and genetic profiles detected by Next-generation sequencing were collected. We further drew nomogram with endpoint of OS after LM, then performed index of concordance (C-index) and survival analysis to evaluate predictive role.4c3880bb027f159e801041b1021e88e8 Result
In total, 61 patients were enrolled and all with genetic profiles from CSF. Patents with high copy number variations (CNVs) or harboring CDK6, TP53 exon5 or FGF19 in CSF demonstrated significant poorer OS than those without (Fig. 1). Cox regression analysis indicated CNVs, CDK6，CDKN2A，TP53，MET and NTRK1 as prognostic factors and further selected for nomogram (Fig. 2). C-index of nomogram was 0.743, indicating the moderate predictive effect. In the calibration curves, we scored the patients based on the model, using bisection and trisection methods to divide into low and high points groups; and low, medium and high points groups (Fig. 3), and significant difference were found in both the survival analyses (NA versus 7.47months, P<0.01) and (NA, 10.33 versus 4.43 months, P<0.01) respectively. Patients who received Osimertinib after LM seemed to have longer OS than those who did not (14.5 months versus 7.7 months) but without significant difference(P＝0.10); however interestingly, in those with EGFR T790M negative who took Osimertinib after LM by themselves obtained survival benefit than those who did not(NA versus 7.7 months, P=0.04), and the results needed to be validated.
Unique genetic profiles from CSF could well predict OS of LM. High CNVs, CDK6, TP53 exon5 or FGF19 in CSF in CSF may be related to poor prognosis of LM.