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Published on: January 17, 2018
An international interpretation study using the ALK IHC antibody D5F3 and a sensitive detection kit demonstrates high
Murry W Wynes1, Lynette M Sholl, Manfred Dietel
1*Department of Medicine, Division of Medical Oncology, University of Colorado, Aurora, Colorado; †Department of Pathology Brigham and Women's Hospital, Boston, Massachusetts; ‡Institute of Pathology, Charité University Hospital Berlin, Germany; §Department of Pathology and Medical Biology, University of Groningen, University Medical Centre Groningen, The Netherlands; ‖Princess Margaret Hospital, University Health Network, University of Toronto, Ontario, Canada; ¶Department of Pathology and Molecular Diagnostics, Aichi Cancer Center, Kanokoden, Chikusa-ku, Nagoya, Japan; #Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, Ohio; ** Department of Pathology, University of Colorado, Aurora, Colorado; and ††University of Colorado Comprehensive Cancer Center, Aurora, Colorado.
Introduction:
The goal of personalized medicine is to treat patients with a therapy predicted to be efficacious based on the molecular characteristics of the tumor, thereby sparing the patient futile or toxic therapy. Anaplastic lymphoma kinase (ALK) inhibitors are effective against ALK-positive non-small-cell lung cancer (NSCLC) tumors, but to date the only 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 a new automated standardized ALK IHC assay.
Methods:
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 combined with OptiView DAB IHC detection and OptiView amplification (Ventana Medical Systems, Inc., Tucson, AZ). Specimens were scored binarily as positive if strong granular cytoplasmic brown staining was present in tumor cells. IHC results were compared with the FISH results and interevaluator comparisons made.
Results:
Overall for the 100 evaluable cases the ALK IHC assay was highly sensitive (90%), specific (95%), and accurate relative (93%) to the ALK FISH results. Similar results were observed using a majority score. IHC negativity was scored by seven of seven and six of seven evaluators on three and two FISH-positive cases, respectively. IHC positivity was scored on two FISH-negative cases by seven of seven readers. There was agreement among seven of seven and six of seven readers on 88% and 96% of the cases before review, respectively, and after review there was agreement among seven of seven and six of seven on 95% and 97% of the cases, respectively.
Conclusions:
On the basis of expert evaluation the ALK IHC test is sensitive, specific, and accurate, and a majority score of multiple readers does not improve these results over an individual reader's score. Excellent inter-reader agreement was observed. These data support the algorithmic use of ALK IHC in the evaluation of NSCLC.
Insights
An automated immunohistochemistry (IHC) test for Anaplastic Lymphoma Kinase (ALK) is a sensitive and specific diagnostic tool for non-small-cell lung cancer (NSCLC). This ALK IHC assay shows high accuracy compared to FISH, supporting its clinical use.
Area of Science:
- Oncology
- Molecular Diagnostics
- Pathology
Background:
- Personalized medicine aims to tailor treatments based on tumor molecular characteristics.
- Anaplastic Lymphoma Kinase (ALK) inhibitors are effective for ALK-positive non-small-cell lung cancer (NSCLC).
- Current companion diagnostics for ALK are limited, with fluorescence in situ hybridization (FISH) being the only approved assay.
Purpose of the Study:
- To evaluate a new, automated, and standardized Anaplastic Lymphoma Kinase (ALK) immunohistochemistry (IHC) assay.
- To assess the sensitivity, specificity, and accuracy of the ALK IHC assay in non-small-cell lung cancer (NSCLC) specimens.
- To compare the performance of the ALK IHC assay against the established ALK FISH diagnostic method.
Main Methods:
- 103 archival non-small-cell lung cancer (NSCLC) specimens previously tested by ALK FISH were stained using an automated ALK IHC assay.
- The assay utilized the anti-ALK (D5F3) primary antibody with OptiView DAB detection and amplification.
- Specimens were scored binarily for strong granular cytoplasmic brown staining, and results were compared with FISH findings and interevaluator agreement was assessed.
Main Results:
- The ALK IHC assay demonstrated high sensitivity (90%), specificity (95%), and accuracy (93%) when compared to ALK FISH results in 100 evaluable cases.
- Excellent inter-observer agreement was achieved, with 95-97% agreement among expert pathologists after review.
- The assay showed high concordance with FISH, with minimal discrepancies in both ALK-positive and ALK-negative cases.
Conclusions:
- The evaluated Anaplastic Lymphoma Kinase (ALK) IHC test is a sensitive, specific, and accurate diagnostic tool for non-small-cell lung cancer (NSCLC).
- Expert evaluation confirmed excellent inter-reader agreement, suggesting reliability of the assay.
- These findings support the use of ALK IHC as an algorithmic approach in the diagnostic evaluation of NSCLC.
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