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A. Fortoul
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P1.07 - Immunology and Immunotherapy (ID 693)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Immunology and Immunotherapy
- Presentations: 1
- Moderators:
- Coordinates: 10/16/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
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P1.07-009 - PD-L1 Expression in Circulating Tumor Cells and Response to PD-1 Inhibitor Treatment in Non-Small Cell Lung Cancer Patients (ID 8494)
09:30 - 09:30 | Author(s): A. Fortoul
- Abstract
Background:
Inhibitors of the immune checkpoint PD-1/PD-L1 (ICI) have become a standard of care in non-small cell lung cancer (NSCLC). The outcomes, although very promising, remain inconstant. Patient selection, currently based on PD-L1 expression in tumor tissue, must be improved, through more dynamic and non-invasive tests. PD-L1 staining of circulating tumor cells (CTCs) could represent such a valuable predictive biomarker.
Method:
Blood samples were prospectively collected from patients with advanced NSCLC before their first infusion of nivolumab. Ten ml of blood were collected and CTCs were isolated on cell size-based technology (ISET, Rarecells). PD-L1 expression was assessed by immunofluroescence (IF) on CTCs and immunochemistry (IHC).
Result:
60 advanced NSCLC patients were included. 45 tissue biopsies were available for PD-L1 expression analysis of: 31.4 (68.9%) and 9 (20%) of biopsies were positive, respectively, using a 5% and a 50% cut-off for tumor cell PD-L1 expression. 56 ISET filters were analyzed. The number of PD-L1(+) CTCs ranged from 1.5 to 47.5 per 7.5mL of blood (median 8.5, 12.5% of CTCs). No correlation between tissue and CTC staining of PD-L1 was observed. A optimal cutoff of 30/7.5mL number of CTCs was determined. Patients with elevated CTCs (>30/7.5mL) experienced a decrease of overall and progression-free survival (p=0.04 and p<0.0001 respectively). PD-L1 expression on CTCs at baseline was not predictive of outcome in the global population but significantly increased in “non-responders” group (PFS <6 months) in comparison with the “responder” group (PFS>6 months) (p=0.02).Figure 1
Conclusion:
We demonstrated the feasibility of PD-L1 detection in CTCs in patients with advanced NSCLC. In our cohort, PD-L1(+) CTCs are associated with a worse outcome. This can be partly explained by the pejorative impact of the number of CTCs that may outweigh its possible predictive value. The interest of PD-L1 assessment on CTC will be likely reinforced by integrating other biomarkers.
