The Relevance of External Quality Assessment for Molecular Testing for ALK Positive Non-Small Cell Lung Cancer: Results from Two Pilot Rounds Show Room for Optimization

Abstract

Background and PurposeMolecular profiling should be performed on all advanced non-small cell lung cancer with non-squamous histology to allow treatment selection. Currently, this should include EGFR mutation testing and testing for ALK rearrangements. ROS1 is another emerging target. ALK rearrangement status is a critical biomarker to predict response to tyrosine kinase inhibitors such as crizotinib. To promote high quality testing in non-small cell lung cancer, the European Society of Pathology has introduced an external quality assessment scheme. This article summarizes the results of the first two pilot rounds organized in 2012–2013.Materials and MethodsTissue microarray slides consisting of cell-lines and resection specimens were distributed with the request for routine ALK testing using IHC or FISH. Participation in ALK FISH testing included the interpretation of four digital FISH images.ResultsData from 173 different laboratories was obtained. Results demonstrate decreased error rates in the second round for both ALK FISH and ALK IHC, although the error rates were still high and the need for external quality assessment in laboratories performing ALK testing is evident. Error rates obtained by FISH were lower than by IHC. The lowest error rates were observed for the interpretation of digital FISH images.ConclusionThere was a large variety in FISH enumeration practices. Based on the results from this study, recommendations for the methodology, analysis, interpretation and result reporting were issued. External quality assessment is a crucial element to improve the quality of molecular testing.

ALK‐rearrangement in non‐small‐cell lung cancer (NSCLC)

“…The FISH break‐apart assay is currently the most reliable approach to ALK testing, but has a number of critical disadvantages. In particular, FISH requires significant time input of extensively trained personnel and cannot be subjected to reasonable automation; furthermore, it demonstrates relatively high failure rates in some sample series and may provide poorly interpretable results in a noticeable fraction of NSCLC cases . Despite these challenges, FISH is still regarded as the gold standard assay for the detection of ALK rearrangements and a comparator for the other ALK detection methods.…”

“…The principle of IHC is based on the fact that activating ALK rearrangements are accompanied by significant overexpression of the catalytic portion of this tyrosine kinase. IHC is generally capable of producing highly reliable results when performed in reference laboratories; however, it requires the standardization of reagents and protocols across pathology laboratories . The Ventana ALK assay used D5F3 antibody is a resultful method of detecting ALK rearrangement.…”

Testing for ROS1 in non-small cell lung cancer: a review with recommendations

“…In 2012, the European Society of Pathology (ESP) proposed an external quality assessment (EQA) scheme to promote high-quality biomarker testing in NSCLC for EGFR mutation analysis and ALK rearrangement detection. From 2014 onwards, ROS1 testing was also included [65]. The EQA was performed at the beginning of the development of ROS1 testing.…”

Novel ALK fusion partners in lung cancer

“…FISH requires significant time input of an extensively trained personnel and cannot be subjected to a reasonable automation; furthermore, it demonstrates relatively high failure rates at least in some sample series and may provide poorly interpretable results in a noticeable fraction of NSCLC cases. In addition, FISH always relies on the purchase of commercial kits, which are highly expensive [2,[6][7][8][9][10][11].…”

“…The principle of IHC is based on the fact that activating ALK rearrangements are accompanied by significant overexpression of the catalytic portion of this tyrosine kinase. IHC is generally capable to produce highly reliable results when performed in reference laboratories, however its interlaboratory reproducibility and performance in heterogenous lung cancer tissue collections remains to be evaluated [8,9,[11][12][13][14]. Use of PCR-based assays is also a common approach for ALK testing.…”