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MA15 - Immunotherapy Prediction (ID 400)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Chemotherapy/Targeted Therapy/Immunotherapy
- Presentations: 1
MA15.05 - PD-L1 Immunohistochemistry as Biomarker in Non-Small Cell Lung Cancer (NSCLC) (ID 4982)
14:20 - 15:50 | Author(s): H. Fabican
Anti-PD1 (programmed cell death 1) therapeutic antibodies have recently become available as a promising option in the treatment of patients with NSCLC in Austria. Several clinical studies suggested PD-L1 (programmed cell death ligand 1) protein expression in tumor cells to be a useful prognostic biomarker using several antibodies and different cutoffs. We studied PD-L1 expression in our NSCLC patient cohort and compared the performance of different antibodies. Furthermore we aimed to investigate the value of PD-L1 expression as a biomarker in a subset of patients treated with Anti-PD1 immunotherapy.
PD-L1-Imunohistochemistry (IHC) was performed in 437 lung cancer specimens (316 adenocarcinomas, 77 squamous cell carcinomas and 44 NSCLC NOS) using the clones SP263 (Ventana), 28.8 (Abcam) and EL1L3N (Cell Signaling) on the VENTANA IHC platform. The percentages of tumor cells (TC) with membranous staining were determined - irrelevant of staining intensity; TC-counts of less than 1 % were interpreted as negative. Staining with at least two of the antibodies was available in 378 specimens (SP263/28.8 in 320 and 28.8/E1L3N in 117). 60 specimens were stained with three antibodies. From 58 patients receiving Nivolumab clinical information about response to therapy was available.
PD-L1 was expressed in 244 specimens (54.84%). 112 (25.63%) showed TC counts ≥50%, and 132 (30.21%) were <50%. 193 (44.16%) were negative. SP263 showed stronger staining intensity than 28.8 and E1L3N. Differences in TC-percentage were seen in 67 of 378 specimens, with major changes in 16 specimens (negative to positive in 4 and <50% to ≥50% in 12 cases). Higher TC percentages were seen with SP263. In the 58 treated patients complete remission was seen in 6 (4 ≥50%, 2 negative), partial remission in 14 (10 ≥50%, 3 <50%, 1 negative), stable disease in 4 (2 <50%, 2 negative), paradox reaction in 7 (1 ≥50%, 3 <50%, 3 negative) and progressive disease in 27 (4 ≥50%, 14 <50%, 9 negative).
PD-L1 is expressed in the majority of NSCLC patients. Despite minor differences in expression levels all three tests provided reliable results. Furthermore PD-L1-IHC showed to be a useful biomarker in NSCLC especially concerning the good response to Anti-PD1 therapy in tumors with PD-L1 expression ≥50%. However as some PD-L1 negative tumors also responded, negative test results cannot definitely exclude patients from immunotherapy.
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