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Frederique Penault-Llorca
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MA26 - New Therapies and Emerging Data in ALK, EGFR and ROS1 (ID 930)
- Event: WCLC 2018
- Type: Mini Oral Abstract Session
- Track: Targeted Therapy
- Presentations: 2
- Moderators:
- Coordinates: 9/26/2018, 13:30 - 15:00, Room 201 BD
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MA26.06 - Crizotinib-Treated ALK Immunopositive Metastasized NSCLC is Associated with an Unfavorable Prognosis when FISH Negative (ID 13179)
14:05 - 14:10 | Author(s): Frederique Penault-Llorca
- Abstract
- Presentation
Background
Metastasized NSCLC with an ALK fusion are sensitive to a range of tyrosine kinase inhibitors. ALK-positive NSCLC has been identified in the pivotal phase III trial with fluorescence in situ hybridization (ALK FISH+). These tumors are also expressing the fusion product (ALK immunohistochemistry (IHC)+). However, discrepant cases occur, including ALK IHC+ FISH-. The aim of this study was to collect ALK IHC+ cases and compare within this group response to crizotinib treatment of ALK FISH+ cases with ALK FISH- cases.
a9ded1e5ce5d75814730bb4caaf49419 Method
A prospective multicenter investigator initiated research study was started in Europe. Stage IV ALK IHC+ NSCLC cases treated with crizotinib were collected centrally. Slides were validated centrally for ALK IHC (with 5A4 ETOP and D5F3 Ventana protocol) and ALK FISH (Vysis probes).
4c3880bb027f159e801041b1021e88e8 Result
The study started April 1, 2014 and closed in November 2017. Fifteen centers participated. Registration of 3523 ALK IHC tests revealed prevalence of 2.6% ALK IHC+ cases. Local ALK FISH analysis resulted in 46 concordant (ALK IHC+/FISH+) and 18 discordant (ALK IHC+/FISH-) cases. Central validation revealed 37 concordant and 6 discordant cases, 5 of which had follow-up. Validation was hampered by limited amount of tissue in biopsy samples. The time to treatment failure did not differ for concordant nor discordant cases, and neither for local nor validated ALK testing (HR=0.78; 95% CI= 0.27-2.3; p=0.64) and (HR=2.2; 95% CI= 0.72-6.5; p=0.16), respectively). However, overall survival was significantly better for concordant cases than discordant cases after central validation (HR=4.5; 95% CI= 1.2-15.9; p=0.010), but not according to local testing (HR=1.7; 95% CI= 0.45-6.2; p=0.44).
8eea62084ca7e541d918e823422bd82e Conclusion
ALK IHC+ FISH- NSCLC cases are an infrequent finding. We recommend such cases to be validated carefully because our data indicate that ALK IHC+ FISH- cases have a worse survival when treated by crizotinib compared to ALK IHC+ FISH+ cases.
This study was funded by an independent research grant by Pfizer
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MA26.07 - ROS1 (SP384) Immunohistochemistry Inter-Reader Precision Between 12 Pathologists (ID 12387)
14:10 - 14:15 | Author(s): Frederique Penault-Llorca
- Abstract
- Presentation
Background
ROS1 positive non-small cell lung cancer (NSCLC) patients can be treated with specific tyrosine kinase inhibitors including crizotinib. ROS1 positivity is often clinically detected by fluorescence in situ hybridization (FISH), however ROS1 IHC can be used to screen samples prior to FISH confirmation of ROS1 status. The ROS1 (SP384) antibody detects ROS1 with high sensitivity, specificity, and consistency. Consistent interpretation of a ROS1 IHC assay between pathologists is important patient evaluation. Here we present inter-reader precision of 12 pathologists across 60 FFPE cases stained with ROS1 (SP384).
a9ded1e5ce5d75814730bb4caaf49419 Method
A retrospective cohort of 60 FFPE NSCLC cases stained with H&E, Rabbit Monoclonal Negative Control Ig, and ROS1 (SP384) were selected to represent positive, negative, and borderline ROS1 IHC status. Twelve practicing lung pathologists independently scored the cases as positive or negative around a cutoff of cytoplasm staining in > 30% tumor cells at a ≥2+ intensity level using Pathotrainer software (Pathomation bvba). Scoring was blinded to other readers and ROS1 status of the cases. Overall percent agreement (OPA), negative percent agreement (NPA), and positive percent agreement (PPA) were calculated in comparison to the group mode. Average overall percent agreement (AOPA), average positive agreement (APA), and average negative agreement (ANA) were calculated pairwise for each reader pair. Following independent assessment, participating pathologists conducted a discordant case review establishing consensus reads for all 60 cases and compared 44 cases to available FISH results.
4c3880bb027f159e801041b1021e88e8 Result
OPA of each of the 12 readers to the mode was 96.4% (95% CI 93.9-98.6) with PPA of 96.3% (95% CI 92.7-99.4) and NPA of 96.5% (95% CI 92.8-99.5). Pairwise AOPA between each of the 12 readers was 94.5% (95%CI 91.2-97.7) with APA 94.0% (95% CI 89.5-97.6) and ANA 95.0% (95%CI 91.2-97.9).
Consensus IHC scores were concordant with FISH 90.0% (40/44 cases).
8eea62084ca7e541d918e823422bd82e Conclusion
Inter-reader precision around a cutoff of >30% tumor cells with cytoplasmic staining at a ≥2+ intensity level was high in interpreting ROS1 (SP384) in NSCLC samples. Case review highlighted confirmation with FISH in questionable cases and staining patterns to be considered when interpreting ROS1 (SP384) IHC.
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