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O04 - Molecular Pathology I (ID 126)
- Event: WCLC 2013
- Type: Oral Abstract Session
- Track: Pathology
- Presentations: 1
- Moderators:I.I. Wistuba, W.A. Cooper
- Coordinates: 10/28/2013, 10:30 - 12:00, Parkside Ballroom A, Level 1
O04.06 - An international standardization study using the ALK IHC antibody D5F3 and a sensitive detection kit demonstrates high concordance between ALK IHC and ALK FISH and between evaluators (ID 2875)
10:30 - 12:00 | Author(s): M. Dietel
The goal of personalized medicine is treating patients with a therapy predicted to be efficacious based on the molecular characteristics of the tumor, thereby sparing the patient futile or detrimental therapy. Anaplastic lymphoma kinase (ALK) inhibitors are effective against ALK positive non-small cell lung cancer (NSCLC) tumors, but to date the only US Food and Drug Administration approved companion diagnostic is a break-apart fluorescence in situ hybridization (FISH) assay. Immunohistochemistry (IHC) is a clinically applicable cost-effective test that is sensitive and specific for ALK protein expression. The purpose of this study was to assemble an international team of expert pathologists to evaluate and standardize the interpretation of a new automated standardized ALK IHC assay.
Archival NSCLC tumor specimens (n=103) previously tested for ALK rearrangement by FISH were provided by the international collaborators. These specimens were stained by IHC with the anti-ALK (D5F3) primary antibody (Ventana Medical Systems, Inc) combined with OptiView DAB IHC detection and OptiView amplification (Ventana Medical Systems, Inc). The evaluators went through an interpretation training session and scored the specimens as positive, if strong granular cytoplasmic brown staining was present in tumor cells, or negative. IHC results were compared to the FISH results and inter-evaluator agreement comparisons made.
Overall for the 100 evaluable cases the ALK IHC assay was highly sensitive (90%), specific (95%) and accurate (93%) relative to the ALK FISH results. Similar results were observed using a majority score. For the discrepant cases IHC negativity was scored by 7/7 on 3 FISH positive cases and 6/7 evaluators on 2 additional FISH positive cases. IHC positivity was scored on 2 FISH negative cases by 7/7 readers. There was agreement among 7/7 and 6/7 readers on 88% and 96%% of the cases before a consensus review, respectively, and following a review there was agreement among 7/7 and 6/7 on 95% and 97% of the cases, respectively.
Based on expert evaluation the ALK IHC assay using the D5F3 antibody combined with Optiview Detction and Optiview amplification is sensitive, specific and accurate, relative to FISH, and a majority score of multiple readers does not improve these results over an individual reader’s score. Excellent inter-reader agreement was observed for the IHC assay. These data support the algorithmic use of ALK IHC as a screening procedure for ALK protein expression in NSCLC.
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P1.06 - Poster Session 1 - Prognostic and Predictive Biomarkers (ID 161)
- Event: WCLC 2013
- Type: Poster Session
- Track: Biology
- Presentations: 1
- Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
P1.06-023 - Anaplastic Lymphoma Kinase (ALK)-detection in Non-small Cell Lung Cancer: results of the first European IHC-based (D5F3-Optiview) panel test within 16 institutes (ID 1825)
09:30 - 16:30 | Author(s): M. Dietel
The study was supported by Ventana Medical Systems, Inc., a Member of the Roche Group Background: The reliable identification of NSCLC patients with anaplastic lymphoma kinase (ALK) gene rearrangement is crucial for the prescription of ALK tyrosine kinase inhibitors (e.g. crizotinib). Whereas the US FDA-approval (2011) is based upon FISH-testing, the European EMA-approval (2012) refers to the definition of “ALK-positive” NSCLCs without mandating a particular test. Therefore a reliable ALK-immunohistochemistry (IHC) could be a promising option in daily routine practice.
Material and methods: To test the reliability of ALK-IHC-diagnosis in a multi-centre environment (17 European institutes from Belgium, Denmark, France, Germany, Scotland, Spain, Sweden and Switzerland) two tissue microarrays (TMA) consisting of 15 NSCLC cases (all adenocarcinomas; 3 cores for each case) were independently tested for ALK-expression by each laboratory using Ventana Medical System’s ALK (D5F3) primary antibody combined with OptiView DAB IHC detection and OptiView Amplification kits. Cases included in the study were unequivocal ALK-break positive or negative (by FISH), as well as so called “ALK-borderline” cases (low percentage of ALK-break positive cells by FISH, around the cut-off of 15%, therefore challenging in diagnosis, but PCR-confirmed as harbouring EML-4-ALK-fusion variants and thus eligible for therapy). Prior to the TMA-based case testing, each participating instrument was qualified using the VENTANA ALK 2 in 1 Control Slides. To provide a uniform baseline interpretation, a webinar-based training was given to all observers. This training included an overview of the ALK Interpretation Guide, a guided review of 50 patient cases using digital whole slide images, and a proficiency exam certifying each observer.
Results: Detailed data analysis was only partly accomplished at the time of abstract submission and will be presented in detail at the “World Conference on LUNG Cancer” in Sydney. Besides the binary evaluation of the cases (ALK-negative vs. ALK-positive) observers were asked to estimate the staining intensity (0-3) within positive cases in correlation to the number of tumor cells and to generate the H-score.
Conclusion: Referring to the EMA-approval text our multi-centre study may contribute to validation and accuracy of IHC-based ALK-testing. Such a validated and reliable IHC-assay could be used: (a) as a good pre-screening method reducing time consuming and costly FISH analysis (shorten turn-around time for test results) and (b) as a final predictive approach in cases with reduced interpretability of FISH results (e.g. minimal tumor cell content in small biopsies, decalcified or artificial altered tissue, FISH in doubt/”borderline”).