ALK Fluorescence In Situ Hybridization Research Articles

False positivity in break apart fluorescence in-situ hybridization due to polyploidy.

In-situ hybridization (ISH) is a diagnostic tool in the detection of chromosomal anomalies, which has important implications for diagnosis, classification and prediction of cancer therapy in various diseases. Certain thresholds of number of cells showing an aberrant pattern are commonly used to declare a sample as positive for genomic rearrangements. The phenomenon of polyploidy can be misleading in the interpretation of break apart fluorescence in-situ hybridization (FISH). The aim of this study is to investigate the impact of cell size and ploidy on FISH results. In sections of varying thickness of control liver tissue and non-small cell lung cancer cases, nuclear size was measured and the number of MET chromogenic ISH and ALK FISH (liver) or ALK and ROS1 FISH (lung cancer) signals was manually counted and quantified. In liver cell nuclei the number of FISH/chromogenic ISH signals increases with nuclear size related to physiological polyploidy and is related to section thickness. In non-small cell lung cancer cases tumour cells with higher ploidy levels and nuclear size have an increased chance of single signals. Furthermore, additional lung cancer samples with borderline ALK FISH results were examined with a commercial kit for rearrangements. No rearrangements could be demonstrated, proving a false positive ALK FISH result. In case of polyploidy there is an increased likelihood of false positivity when using break apart FISH probes. Therefore, we state that prescribing one single cut-off in FISH is inappropriate. In polyploidy, the currently proposed cut-off should only be used with caution and the result should be confirmed by an additional technique.

Abstract 1271: Detection of ALK, ROS1 and RET fusion transcripts in FFPE samples of non-small cell lung cancer patients using a novel RT-PCR based assay

Abstract Background and objective: Detection of genomic rearrangements like ALK fusions are mandatory in non-small cell lung cancer (NSCLC) as those alterations can be targeted by an increasing number of drugs. Fluorescence in-situ hybridization (FISH) is the gold standard but multiplexed technologies allow the analysis of several targets simultaneously. We have evaluated a novel RT-PCR based assay for the detection of ALK, ROS1 and RET rearrangement in NSCLC patients in this research study. Materials and Methods: FFPE tissue sections from 309 patients with late stage NSCLC were screened for ALK and ROS1 status using immunohistochemistry (IHC) and confirmed with FISH. Total nucleic acids were extracted from tissue sections using the Maxwell RSC RNA FFPE kit (Promega). Fusions were detected by RT-PCR using a prototype ALK/RET/ROS1 Fusion Panel assay (Roche). A subset of discordant cases were further analyzed by RNA sequencing using the QIAseq Targeted RNAscan Lung Cancer Panel (Qiagen). Results: All 309 samples were tested by RT-PCR with a 0% invalid rate. ALK fusions were detected in 39 samples: 29 were ALK FISH+, 5 were ALK FISH not contributive, 3 were ALK FISH- (less than 15% tumor cells presenting a gene fusion), and 2 were ALK IHC- and not tested by FISH. ROS1 fusions were detected in 12 samples: 9 were ROS1 FISH+, 1 was ROS1 FISH-, and 2 were ROS1 IHC- and not tested by FISH. RET fusions were detected in 3 samples. The remaining 255 samples were RT-PCR-: 5 were ALK FISH+ containing fusions not covered by the RT-PCR assay, 1 was ALK FISH+ containing ALK polysomy, 1 was ROS1 FISH+ containing a fusion not covered by the RT-PCR assay, 1 was ROS1 FISH+ containing ROS1 amplification, 1 was ROS1 FISH+ but ROS1 RNAseq-, and 246 samples were IHC- or IHC+/FISH-. The overall concordance rate between RT-PCR and FISH for ALK and ROS1 gene rearrangements was 91.9%. Although the RT-PCR assay did not detect 5 ALK and 1 ROS1 fusions due to design limitations, it did identify the presence of fusions in 9 tumors that were undetected by FISH (8 ALK and 1 ROS1). Conclusion: Using limited amount of biological material, RT-PCR was able to detect a substantial majority of ALK and ROS1 fusions identified by FISH, as well as fusions that were missed by the initial IHC/FISH screening. This study demonstrates RT-PCR as a feasible approach to detecting fusions in NSCLC. Citation Format: Marc G. Denis, Audrey Vallée, Christine Sagan, Guillaume Herbreteau, Sandrine Charpentier, Jaya Rajamani, Michael Lee, Ellen Ordinario. Detection of ALK, ROS1 and RET fusion transcripts in FFPE samples of non-small cell lung cancer patients using a novel RT-PCR based assay [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1271.

Assessment of ALK Fusions in Uncommon Inflammatory Myofibroblastic Tumors With ALK IHC Positivity but FISH-Equivocal Findings by Targeted RNA Sequencing.

Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) are common methods to detect ALK status in inflammatory myofibroblastic tumors (IMTs). However, equivocal ALK FISH signals and inconsistency between FISH and IHC are occasionally observed. To study the inconsistency between FISH and IHC, and clarify ALK status in IMT by targeted RNA sequencing (RNAseq). In this study, 12 consultation cases preliminarily diagnosed as uncommon IMTs with ALK IHC positivity but FISH negativity, plus 3 ALK-positive and 3 ALK-negative IMTs, were re-analyzed by IHC, FISH, and RNAseq. As a result, 1 case with FUS-TFCP2 fusion was detected by RNAseq, which was previously misdiagnosed as IMT. In the other 11 uncommon IMTs, 90.9% (10 of 11) showed equivocal ALK FISH signals, and all were confirmed to harbor ALK fusion by RNAseq, except for 1 failure, suggesting that a low threshold for ALK FISH might be proposed in IMT. Furthermore, RNAseq also identified IGFBP5-ALK in 1 case with ALK IHC positivity but typical FISH negativity, suggesting the possibility of false negatives for ALK FISH. For the typical IMTs, ALK fusion was identified by RNAseq in all 3 ALK-positive IMTs as expected, and additionally FN1-ROS1 fusions were identified in 2 of 3 ALK-negative IMTs. These findings indicated that RNAseq can simultaneously detect multiple gene fusions and provide fusion forms and breakpoints, which is of great value for differential diagnosis, especially for those uncommon IMTs with equivocal FISH findings or inconsistency between IHC and FISH.

Histologic and Molecular Characterization of Non-Small Cell Lung Carcinoma With Discordant ROS1 Immunohistochemistry and Fluorescence In Situ Hybridization.

ROS1 immunohistochemical (IHC) positivity requires follow-up with confirmatory testing such as fluorescence in situ hybridization (FISH). Identifying predictive characteristics of false positive ROS1 IHC cases could aid in optimizing testing algorithms, decrease testing costs and preserve tissue. Retrospective results were retrieved for 2054 patients with non-small cell lung carcinoma submitted to our laboratory for molecular testing. Reflex ROS1 FISH was done on all ROS1 immunoreactive cases using ROS1 D4D6 antibody. Staining intensity and histo-score was recorded for all ROS1 immunoreactive cases. Results of any additional molecular testing (KRAS, BRAF, EGFR, ALK FISH, RET FISH, MET FISH) were also tabulated. ROS1 immunoreactivity was seen in 305/2054 (14.8%) cases. Immunoreactivity was weak in majority of the cases with only 4.6% cases having an histo-score >100 and 5.9% of cases had moderate staining intensity. FISH was negative in 99% (302/305) cases with any degree of IHC expression (discordant cases) while 3 cases were positive by FISH. Diffuse strong IHC staining in greater than 90% of the tumor was noted in 6 cases, 3 (0.98%) of which were confirmed to have ROS1 rearrangement by FISH. The discordant cases had significantly higher rates of EGFR mutations (P<0.0005) in comparison to ROS1 IHC negative cases, were seen more often in adenocarcinoma and adenosquamous cell carcinoma (P<0.0005) with lepidic and acinar patterns, and more likely to occur in primary lung carcinomas (P<0.0005). False positive ROS1 immunoreactivity was very frequent, occurred more commonly in primary NSCLC cases with acinar and/or lepidic histologies and was more likely in EGFR mutated cases. Using higher positivity thresholds for ROS1 IHC and incorporating the histologic and molecular correlates into algorithmic strategies could result in increased specificity and clinical utility of ROS1 IHC assay.

FISH patterns of ROS1, MET, and ALK with a correlation of ALK immunohistochemistry in lung cancer: a case for introducing ALK immunohistochemistry 'Equivocal' interpretation category in the Ventana anti-ALK (D5F3) CDx assay - A tertiary cancer center experience.

Mutations in ROS1, ALK, and MET genes are targetable alterations in non-small cell lung cancer (NSCLC). They can be evaluated by different techniques, most commonly fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). We explored the prevalence of ROS1, ALK, MET mutations, discuss clinicopathological associations and FISH signal patterns on 413 consecutive cases of EGFR negative lung carcinoma from March 2016 to April 2017 using FISH for ALK, ROS1, and MET along with ALK (D5F3) IHC. ROS1 gene rearrangement, ALK positivity (IHC and/or FISH), and MET amplification were seen in 18/358 (5%) cases, 76/392 cases (19.4%), and 10/370 (2.7%) cases, respectively. ALK FISH and ALK IHC were positive in 51/300 (17%) and 58/330 cases (17.57%), respectively, while 8/330 (2.4%) cases were ALK IHC "equivocal" of which 3/8 (37.5%) were ALK FISH positive. Of ALK FISH and IHC co-tested cases, 43/238 (18.07%) cases were positive by both techniques, while 15/43 (34.88%) of ALK positive cases showed discordant ALK FISH and IHC results. All ROS1 rearranged and MET amplified cases were adenocarcinoma. Signet ring cell histology was associated with 78.57% likelihood of being either ALK or ROS1 positive. Genomic heterogeneity was seen in 30% of MET amplified cases. ALK/ROS1/MET gene alterations were found in 25.18% of NSCLC cases. An ALK IHC "equivocal" interpretation category should be incorporated into practice. Atypical patterns of ROS1 and genomic heterogeneity need to be evaluated further for any clinical relevance.

Detection of ALK and ROS1 fusion transcripts in FFPE samples of non-small cell lung cancer patients using a novel RT-PCR based assay and targeted RNA sequencing.

e21695 Background: Detection of genomic rearrangements like ALK and ROS1 fusions are mandatory in non-small cell lung cancer (NSCLC) as those alterations can be targeted by an increasing number of drugs. Fluorescence in-situ hybridization (FISH) has been so far the gold standard but multiplexed technologies would allow analysis of many potential targets simultaneously. We have evaluated a novel RT-PCR based assay and a targeted RNA sequencing solution for the detection of ALK and ROS1 rearrangement in NSCLC patients. Methods: 41 patients with late stage NSCLC were included in the study. ALK and ROS1 status were screened on FFPE tissue sections using immunohistochemistry and confirmed with FISH. Total nucleic acids were extracted from tissue sections using the Maxwell RSC RNA FFPE kit (Promega). Detection of rearrangements was performed by RT-PCR using the prototype ALK/RET/ROS1 Fusion Panel assay (Roche), which detects 7 ALK fusion variants, 13 ROS1 variants and 6 RET variants. For RNA sequencing, the libraries were prepared with the QIAseq Targeted RNAscan Lung Cancer Panel (Qiagen). Sequencing was performed on a MiSeq instrument (Illumina). Results: We tested 16 ALK FISH+ tumors, 4 ROS1 FISH+ tumors, and 21 samples that were either IHC- or IHC+/FISH-. The RT-PCR assay detected 15 of the 16 ALK FISH+ tumors, and 3 of the 4 ROS1 FISH+ tumors. In the 21 IHC- or IHC+/FISH- samples, 1 additional ROS1 fusion and 1 RET fusion were detected. The remaining 19 assays samples were negative. 2 fusions were missed by RT-PCR because the assay design does not cover these rearrangements (KLC1-ALK and CTNND1-ROS1). With targeted RNA sequencing, we were able to detect 14 of the 16 ALK FISH+ tumors and all 4 of the ROS1 FISH+ tumors. We also identified 1 additional ROS1 fusion and 1 RET fusion in the 21 IHC- or IHC+/FISH- samples. 17 patients were negative and 2 tests were not contributive. Overall, using FISH as a reference, the sensitivity of both assays was 90% (18/20). Conclusions: Using limited amount of biological material, both RT-PCR and targeted RNA sequencing were able in one assay to detect the overwhelming majority of ALK and ROS1 fusions identified with FISH. These approaches also allowed us to detect gene rearrangements that were missed by the initial IHC/FISH screening. The RT-PCR assay requires less RNA (as little as 3 ng) and has a much faster turn-around time. The RNA sequencing approach allowed us to identify the fusion partners, but it requires much more RNA and is rather difficult to implement in routine practice.

P1.16 A Study on Clinicopathological Features and Diagnostic Methods of ALK Fusion-Positive Non-Small Cell Lung Cancer in KR

Lung cancer is one of the most common malignancies and the leading cause of cancer-related death in Korea. A lot of efforts have been put into to develop new, more effective treatments and biological markers to predict the therapeutic responses, leading to the discovery of various genetic changes, the so-called “growth drivers” of carcinogenesis. Some genetic alterations have become the new treatment targets, and there have been suggestions that different mutations are associated with different clinicopathological characteristics and prognosis. In this study we aimed to evaluate the status of the key “driver” mutation ALK fusion in Korean non-small cell lung cancer patients and its association with the clinicopathological characteristics, including the presence of other genetic mutations. We also compared different methods for ALK fusion detection, i.e., fluorescence in situ hybridization (FISH), immunohistochemistry (IHC), and next-generation sequencing (NGS) analyses to find out which method would the most effective. A total of 482 NSCLC patients who underwent ALK FISH test were evaluated for clinicopathological features such as age, sex, smoking history, tumor stage, histological subtype, immunohistochemical profile including ALK, EGFR mutation status and survival. Some ALK FISH-positive and -negative cancers were newly submitted to NGS analysis for DNA and RNA alterations. The ALK fusion-positive tumors were associated with younger age, more female patients, frequent nodal metastases and advanced stage, and short survival. The diagnostic agreement rates among ALK FISH, ALK IHC, and NGS ranged from about 60 to 90% and when considering the patient outcome as a measurement of the test efficacy, the ALK FISH may not be the most reliable one in diagnosis of ALK fusion-positive lung cancer. The NGS analysis detected various additional genetic alterations never considered at the time of diagnosis, including NPM3-TRK rearrangement. Comparing the results of ALK FISH, IHC and NGS, we concluded in practice ALK testing should better be diversified concerning FISH and IHC, and NGS analysis would be a good alternative of ALK FISH with an additional advantage of simultaneous detection of different mutations.

Combining ALK Fluorescent In Situ Hybridization and Immunohistochemistry to Analyze Multiple Non-Small Cell Lung Carcinoma Samples per Patient Reveals Intermethod and Intersample-discrepant Results.

ALK inhibitors have improved the therapeutic management of patients with ALK-rearranged advanced non-small cell lung cancers (NSCLC). Several diagnostic methods, mainly fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC), can be used as single or combined tests to detect the so-called "ALK-positive" NSCLC. Intersample and intermethod discrepancies could cause issues with therapeutic consequences in ALK testing. In this article, we report a case series of our real-life experience and issues in combining FISH and IHC in multiple tumor samples per patient to diagnose and treat a subset of "ALK-positive" patients with NSCLC. Among analyses conducted in 40 samples of 18 patients with advanced lung adenocarcinomas, we retrospectively encountered 10 patients with intersample-concordant ALK FISH and IHC results. Discrepant results about FISH and/or IHC were noted between different samples in 8 patients. Therapeutic responses were observed in 5 of 10 crizotinib-treated patients including 1 patient with ALK FISH+ IHC- status and 1 patient with ALK FISH- IHC+ status. Our data highlight the difficulty to predict the response/nonresponse to crizotinib therapy, in patients with advanced NSCLC, not only on the basis of single and multiple tumor samples, but also on the basis of single and combined diagnostic methods.

Next-generation Sequencing for ALK and ROS1 Rearrangement Detection in Patients With Non–small-cell Lung Cancer: Implications of FISH-positive Patterns

BackgroundDetection of ALK and ROS1 gene rearrangements in non–small-cell lung cancer is required for directing patient care. Although fluorescence in situ hybridization (FISH) and immunohistochemistry have been established as gold standard methods, next-generation sequencing (NGS) platforms are called to be at least equally successful. Comparison of these methods for translation into daily use is currently under investigation. Patients and MethodsForty non–small-cell lung cancer paraffin-embedded samples with previous ALK (n = 33) and ROS1 (n = 7) FISH results were examined with the Oncomine Focus Assay and tested for ALK and ROS1 immunoreactivity. Clinical implications of concurrent molecular alterations and concordance between methods were evaluated. ResultsNGS was successful in 32 (80%) cases: 25 ALK and 7 ROS1. Few concomitant alterations were detected: 1 ALK rearranged case had an ALK p.L1196M-resistant mutation, 4 had CDK4, MYC, and/or ALK amplifications, and 1 ROS1 rearranged case showed a FGFR4 amplification. Comparison between techniques revealed 5 (16%) discordant cases that had lower progression-free survival than concordant cases: 7.6 (95% confidence interval, 2.2-13) versus 19.4 (95% confidence interval, 10.1-28.6). Remarkably, 4 of these cases had isolated 3' signal FISH pattern (P = .026). ConclusionOur data support that the identification of 3' isolated signal FISH pattern in ALK and ROS1 cases might suggest a false-positive result. NGS seems a reliable technique to assess ALK and ROS1 rearrangements, offering the advantage over immunohistochemistry of detecting other molecular alterations with potential therapeutic implications.

Evaluation of a Dual ALK/ROS1 Fluorescent In Situ Hybridization Test in Non–Small-cell Lung Cancer

BackgroundSeveral therapeutics targets have emerged to treat patients with non–small-cell lung carcinoma (NSCLC), with numerous biomarkers available to test for treatment choices. Minimum tumor wastage is necessary to permit the analysis of every potentially relevant target. Searching for targetable ALK and ROS1 rearrangements is now mandatory in NSCLC. In the present study, we evaluated the performance of a dual ALK/ROS1 fluorescent in situ hybridization (FISH) probe that concurrently analyzed the 2 oncogenes on a same FISH slide. Materials and MethodsWe used the FlexISH ALK/ROS1 DistinguISH Probe (Zytovision, Bremerhaven, Germany) to analyze a set of 28 formalin-fixed paraffin-embedded NSCLC tumor samples enriched in tumors with ALK- and ROS1-rearranged status. ResultsThe dual ALK/ROS1 FISH probe test results were fully concordant with the results of previous single ALK and ROS1 FISH tests (15 ALK and 3 ROS1 rearrangements) without any false-positive results. Dual- and single-probe FISH test results were also concordant regarding the unusual ALK FISH patterns. These included 1 sample that had negative FISH results with diffuse single 5′-ALK signals and positive ALK immunohistochemistry findings in a patient with a response to crizotinib, 2 paired samples with high percentages of ALK FISH-rearranged nuclei despite negative ALK immunohistochemistry findings, and ALK FISH-positive samples from 2 patients lacking a response to crizotinib therapy despite concordant ALK FISH and immunohistochemistry-positive results. ConclusionThe dual ALK/ROS1 FISH probe test is a valuable tool to search concurrently for both ALK and ROS1 rearrangements on a same FISH slide and could help to spare tumor tissue for other biomarkers tests.

Relationship between driver gene mutations, their relative protein expressions and survival in non-small cell lung carcinoma in Macao.

We report the status of most common gene mutations in non-small cell lung carcinoma (NSCLC) in Macao, and explore the relationship between each gene mutation and clinicopathologic features and survival. EGFR, KRAS and BRAF mutations were detected by PCR in 122 cases of NSCLC. ALK translocation and MET amplification were detected by fluorescence in situ hybridization (FISH). MET and thyroid transcription factor (TTF-1) were investigated by immunohistochemistry. Clinical data were collected for analyzing their correlation with the gene mutations. The mutation of EGFR, KRAS and BRAF was detected in 48 (39.3%), 13 (10.7%) and 3 (2.5%) of 122 cases of NSCLC, respectively. ALK translocation and MET amplification were detected in 7 (5.7%) and 3 cases (2.5%). The rate of EGFR mutation was significantly higher in female and non-smoker patients. In TTF-1 positive cases EGFR mutation was more frequent. Age of the patients over 62-year old was correlated with KRAS mutations. The concordance between ALK IHC and FISH was 58.3%. The MET protein in the cases with MET amplification was 100% positive. The survival was lower in the patients with positive MET protein than those with negative. MET protein was an independent prognostic factor for NSCLC. EGFR mutation occurred frequently in the female never smoke patients with NSCLC. KRAS mutation was more common in old patients. Negative MET protein expression could be used as a negative predictive marker of MET amplification. MET protein expression was an independent prognostic factor for NSCLC.

Molecular Profiling of Malignant Pleural Effusion in Metastatic Non-Small-Cell Lung Carcinoma. The Effect of Preanalytical Factors.

Non-small-cell lung cancer (NSCLC)-associated malignant pleural effusions (MPEs) are sometimes the only available specimens for molecular analysis. This study evaluates diagnostic yield of NSCLC-associated MPE, its adequacy for molecular profiling and the potential influence of MPE volume/cellularity on the analytic sensitivity of our assays. Molecular results of 50 NSCLC-associated MPE cases during a 5-year period were evaluated. Molecular profiling was performed on cell blocks and consisted of fluorescent in situ hybridization (FISH) for ALK gene rearrangements and the following sequencing platforms: Sanger sequencing (for EGFR) and high-throughput pyrosequencing (for KRAS and BRAF) during the first 4 years of the study period, and targeted next-generation sequencing performed thereafter. A total of 50 NSCLC-associated MPE cases were identified where molecular testing was requested. Of these, 17 cases were excluded: 14 cases (28%) due to inadequate tumor cellularity and 3 cases due to unavailability of the slides to review. A total of 27 out of 50 MPE cases (54%) underwent at least EGFR and KRAS sequencing and FISH for ALK rearrangement. Of the 27 cases with molecular testing results available, a genetic abnormality was detected in 16 cases (59%). The most common genetic aberrations identified involved EGFR ( 9 ) and KRAS ( 7 ). Six cases had ALK FISH only, of which one showed rearrangement. MPE volume was not associated with overall cellularity or tumor cellularity (P = 0.360). Molecular profiling of MPE is a viable alternative to testing solid tissue in NSCLC. This study shows successful detection of genetic aberrations in 59% of samples with minimal risk of false negative.

Multiplexed transcriptome analysis to detect ALK, ROS1 and RET rearrangements in lung cancer

ALK, ROS1 and RET gene fusions are important predictive biomarkers for tyrosine kinase inhibitors in lung cancer. Currently, the gold standard method for gene fusion detection is Fluorescence In Situ Hybridization (FISH) and while highly sensitive and specific, it is also labour intensive, subjective in analysis, and unable to screen a large numbers of gene fusions. Recent developments in high-throughput transcriptome-based methods may provide a suitable alternative to FISH as they are compatible with multiplexing and diagnostic workflows. However, the concordance between these different methods compared with FISH has not been evaluated. In this study we compared the results from three transcriptome-based platforms (Nanostring Elements, Agena LungFusion panel and ThermoFisher NGS fusion panel) to those obtained from ALK, ROS1 and RET FISH on 51 clinical specimens. Overall agreement of results ranged from 86–96% depending on the platform used. While all platforms were highly sensitive, both the Agena panel and Thermo Fisher NGS fusion panel reported minor fusions that were not detectable by FISH. Our proof–of–principle study illustrates that transcriptome-based analyses are sensitive and robust methods for detecting actionable gene fusions in lung cancer and could provide a robust alternative to FISH testing in the diagnostic setting.

ALK+ lung adenocarcinoma in never smokers and long-term ex-smokers: prevalence and detection by immunohistochemistry and fluorescence in situ hybridization.

ALK gene rearrangements are identified in 2-5% of all non-small cell lung cancer and are more common in lifetime non-smokers with adenocarcinoma, but the prevalence of ALK rearrangements is not as well characterized in long-term ex-smokers (quit >10years prior to diagnosis). Accurate and timely diagnosis of ALK-rearranged tumors is of clinical importance given the remarkable response to targeted inhibitors. ALK gene rearrangement may be detected by fluorescence in situ hybridization (FISH), and abnormal expression of ALK protein may be detected by immunohistochemistry (IHC), the latter of which is faster and less expensive. The aim of this study is to evaluate the prevalence of ALK rearrangement in non-smokers and long-term ex-smokers with lung adenocarcinoma and to assess the performance of IHC for the detection of ALK+ tumors when compared to FISH. Two hundred fifty-one cases of resected lung adenocarcinoma were retrospectively reviewed, including non-smokers (n=79) or long-term ex-smokers (n=172). ALK IHC and ALK FISH were performed on each case. Four cases demonstrated ALK rearrangement by FISH (4/251; 1.6%). All cases were non-smokers (4/79; 5.1%), and all were positive for ALK by IHC. No additional cases were considered positive by IHC, and only 26 (10.4%) cases were considered equivocal using a conservative approach to interpretation, resulting in a sensitivity of 100% and specificity of 89.5%. ALK rearrangement was not observed in lung adenocarcinoma arising in long-term ex-smokers, whereas it is seen in up to 5.1% of lifetime non-smokers. ALK IHC using the 5A4 antibody demonstrates high sensitivity, supporting its use as a screening test.

Inconsistent results in the analysis of ALK rearrangements in non-small cell lung cancer.

BackgroundIdentification of targetable EML4-ALK fusion proteins has revolutionized the treatment of a minor subgroup of non-small cell lung cancer (NSCLC) patients. Although fluorescence in situ hybridization (FISH) is regarded as the gold standard for detection of ALK rearrangements, ALK immunohistochemistry (IHC) is often used as screening tool in clinical practice. In order to unbiasedly analyze the diagnostic impact of such a screening strategy, we compared ALK IHC with ALK FISH in three large representative Swedish NSCLC cohorts incorporating clinical parameters and gene expression data.MethodsALK rearrangements were detected using FISH on tissue microarrays (TMAs), including tissue from 851 NSCLC patients. In parallel, ALK protein expression was detected using IHC, applying the antibody clone D5F3 with two different protocols (the FDA approved Ventana CDx assay and our in house Dako IHC protocol). Gene expression microarray data (Affymetrix) was available for 194 patients.ResultsALK rearrangements were detected in 1.7 % in the complete cohort and 2.0 % in the non-squamous cell carcinoma subgroup. ALK protein expression was observed in 1.8 and 1.4 % when applying the Ventana assay or the in house Dako protocol, respectively. The specificity and accuracy of IHC was high (> 98 %), while the sensitivity was between 69 % (Ventana) and 62 % (in house Dako protocol). Furthermore, only 67 % of the ALK IHC positive cases were positive with both IHC assays. Gene expression analysis revealed that 6/194 (3 %) tumors showed high ALK gene expression (≥ 6 AU) and of them only three were positive by either FISH or IHC.ConclusionThe overall frequency of ALK rearrangements based on FISH was lower than previously reported. The sensitivity of both IHC assays was low, and the concordance between the FISH and the IHC assays poor, questioning current strategies to screen with IHC prior to FISH or completely replace FISH by IHC.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2646-x) contains supplementary material, which is available to authorized users.

Custom Gene Capture and Next-Generation Sequencing to Resolve Discordant ALK Status by FISH and IHC in Lung Adenocarcinoma

IntroductionWe performed a genomic study in lung adenocarcinoma cases with discordant anaplastic lymphoma receptor tyrosine kinase gene (ALK) status by fluorescent in situ hybridization (FISH) and immunohistochemical (IHC) analysis. MethodsDNA from formalin-fixed paraffin-embedded tissues of 16 discordant (four FISH-positive/IHC–negative and 12 FISH-negative/IHC–positive) cases by Vysis ALK Break Apart FISH and ALK IHC testing (ALK1 clone) were subjected to whole gene capture and next-generation sequencing (NGS) of nine genes, including ALK, echinoderm microtubule associated protein like 4 gene (EML4), kinesin family member 5B gene (KIF5B), staphylococcal nuclease and tudor domain containing 1 gene (SND1), BRAF, ret proto-oncogene (RET), ezrin gene (EZR), ROS1, and telomerase reverse transcriptase (TERT). All discordant cases (except one FISH-negative/IHC–positive case without sufficient tissue) were analyzed by IHC with D5F3 antibody. In one case with fresh frozen tissue, whole transcriptome sequencing was also performed. Twenty-six concordant (16 FISH-positive/IHC–positive and 10 FISH-negative/IHC–negative) cases were included as controls. ResultsIn four ALK FISH-positive/IHC–negative cases, no EML4-ALK fusion gene was observed by NGS, but in one case using fresh frozen tissue, we identified EML4–baculoviral AIP repeat containing 6 gene (BIRC6) and AP2 associated kinase 1 gene (AAK1)-ALK fusion genes. Whole transcriptome sequencing revealed a highly expressed EML4-BIRC6 fusion transcript and a minimally expressed AAK1 transcript. Among the 12 FISH-negative/IHC–positive cases, no evidence of ALK gene rearrangement was detected by NGS. Eleven of 12 FISH-negative/IHC–positive cases detected by ALK1 clone were concordant by repeat ALK IHC with D5F3 antibody (i.e., FISH-negative/IHC–negative by D5F3 clone). Among the 16 ALK FISH-positive/IHC–positive positive controls, whole gene capture identified ALK gene fusion in 15 cases, including in one case with Huntington interacting protein 1 gene (HIP1)-ALK. No ALK fusion gene was observed in any of the 10 FISH-negative/IHC–negative cases. Other fusion genes involving ROS1, EZR, BRAF, and SND1 were also found. ConclusionsALK FISH results appeared to be false-positive in three of four FISH-positive/IHC–negative cases, whereas no false-negative ALK FISH case was identified among 12 ALK FISH-negative/IHC–positive cases by ALK1 clone, which was in keeping with the concordant FISH-negative/IHC–negative status by D5F3 clone. Our targeted whole gene capture approach using formalin-fixed paraffin embedded samples was effective for detecting rearrangements involving ALK and other actionable oncogenes.

Abstract A33: Utility of multiplexed biomarker analysis in non-small-cell lung cancer patients with discrepancies between FISH and immunohistochemical results of ALK testing

Abstract Background: The clinical implications in Non-small cell lung cancer (NSCLC) patients with discrepancy between fluorescent in situ hybridization (FISH) and immunohistochemistry (IHC) assessing ALK status are unclear. Materials and Methods: From 1131 archived tissue samples, we identified 41 NSCLC patients with discrepant results showing positive or borderline ALK FISH and negative IHC using ALK1 antibody. Of these, 21 cases with sufficient tissue remaining for selected reaction monitoring (SRM) and an additional case within normal range FISH split (4%) were sent to confirm ALK IHC using other antibodies (5A4 and D5F3). Target protein levels measured by multiplexed SRM were correlated with records of clinical outcomes after treatment with crizotinib or cytotoxic chemotherapy. Results: Of 22 cases with various ALK FISH results and negative IHC (ALK1), IHC using other antibodies (5A4 and D5F3) identified 4 positive cases, whereas the SRM assay identified 7 cases with tumor-specific ALK protein. IHC showed lower sensitivity in specimen with delayed fixation but SRM showed superior sensitivity in those samples as SRM is independent to modified epitope. Of 8 crizotinib-treated cases, 4 cases with detectable levels of either ALK or cMET proteins had complete or partial responses; cases without either of these proteins (n = 4) did not respond to crizotinib regardless of ALK FISH results. Cases with 3 or more predictive proteins specific to chemotherapeutic agents were found to be more responded to those agents and had a higher probability of progression-free survival. Conclusions: The SRM assay showed superior sensitivity in poorly fixed specimens and can inform therapeutic decision-making in NCSLC patients with ALK screening discordances. Citation Format: TAE-JUNG KIM, HIDEKI TERAI. Utility of multiplexed biomarker analysis in non-small-cell lung cancer patients with discrepancies between FISH and immunohistochemical results of ALK testing. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A33.

Abstract 4244: Comparison of different ALK tests in non-small cell lung cancer (NSCLC) patients treated with crizotinib and their clinical outcome

Abstract Background: The screening algorithm for detection of ALK-rearranged NSCLC is still under investigation. The Break-Apart ALK FISH is the standard diagnostic test for the treatment with crizotinib. However, immunohistochemistry (IHC) with different antibodies shows excellent results when compared to ALK FISH. The efficacy of crizotinib is studied in relation to ALK FISH. We compared IHC outcome and the number of ALK breaks estimated with FISH with clinical outcome. Methods: Patients treated with crizotinib who had biopsies with sufficient tumor tissue were selected. Tumour response was assessed by CT using RECIST. Fluorescence in situ hybridization (FISH) was performed with Vysis LSI ALK Break Apart FISH Probe KIT (Abbott Molecular) and immunohistochemistry with Ventana ALK IHC Kit using D5F3 antibody. Results: Twenty one patients with NSCLC were selected, median (range) age 54 yrs (21-75); 19 had adenocarcinoma, 2 had large-cell carcinoma. We confirmed the presence of EML4-ALK fusions in all samples either by FISH or IHC. Median percentage of ALK breaks was 47% (6-76). Tumour response occurred in 12 pts having a median of 51 (6-76) breaks and 9 non-responders having a median of 27 (15-64) breaks. Of the 12 responders, 8 pts had positive IHC (67%), 3 were negative and 1 was not done; the FISH negative, IHC positive patient was one of the responders. Of the 9 non-responders 2 had positive IHC (22%), 3 negative (33%), and 1 was equivocal and 3 not done. Median PFS for positive IHC is 7.9 mo (95% CI., 5.5 - 10.3) and for negative IHC 1.6 mo (1.3 - 1.8), n = 17, p&amp;lt;0.0001. OS survival data are 6.5 mo (95% CI., 0 - 17.8) and 18.3 mo (95% CI., 11.1 - 25.6) respectively, n = 17 p = 0.052. PFS above 30% number of breaks was 7.0 mo (95% CI., 1.8 - 12.2) versus PFS below is 1.8 mo (95% CI., 0.7 - 2.9), n = 21, p = 0.05. OS survival data are 4.1 mo (95% CI., 0 - 9.3) and 16.1 mo (95% CI., 9.0 - 23.2) respectively, n = 21 p = 0.003. Therefore PFS and OS is more prolonged in those tumors who have ALK breaks above 30%. IHC difference are only significant for PFS. Conclusions: Both ALK FISH and IHC identify NSCLC patients who benefit from crizotinib treatment. Patients with ALK breaks above 30% have a better PFS and OS. IHC only differentiates for PFS. Citation Format: Anthonie J. van der Wekken, Thijo JN Hiltermann, Wim Timens, Ed Schuuring, Harry JM Groen. Comparison of different ALK tests in non-small cell lung cancer (NSCLC) patients treated with crizotinib and their clinical outcome. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4244. doi:10.1158/1538-7445.AM2015-4244

ALK and ROS1 rearrangements tested by fluorescence in situ hybridization in cytological smears from advanced non-small cell lung cancer patients.

The identification of ALK and ROS1 rearrangements and the availability of an effective target therapy, such as crizotinib, represent a new option in the treatment of advanced non-small cell lung cancer (NSCLC) patients. In light of recent advances in non-invasive diagnostic procedures, we aimed to demonstrate that direct cytological smears are suitable for assessing ALK and ROS1 rearrangements in patients with NSCLC. Fifty-five patients with a cytological diagnosis of lung adenocarcinoma (ADC) were evaluated for ALK rearrangements by fluorescence in situ hybridization (FISH) and 12 patients for ROS1 FISH rearrangements. Seventeen of the 55 cytological samples tested for ALK were obtained from the primary tumor and 38 from metastatic lesions. Ten of 12 samples evaluated for ROS1 were obtained from metastatic sites and two from the primary tumor. ALK FISH was successful in 49/55 (89%) cytological ADC samples and ROS1 FISH in all 12 cytological samples. ALK rearrangements were found in 3/13 (23%) primary tumors and 7/36 (19%) metastatic sites. ROS1 rearrangements were found in one of the two primary tumors and in two of the 10 metastases. Two of the three rearranged cases were tested on cytology after knowing that they were rearranged on histology in order to increase representativeness of ROS1 rearranged cases in this study. Whenever cytology represents the only available material for diagnosis and biological characterization of NSCLC, minimally invasive procedures may provide an additional important source of cellular material for FISH assessment of ALK and ROS1 rearrangements.

The role of immunohistochemical analysis in the evaluation of EML4-ALK gene rearrangement in lung cancer.

Among the mutations described in non-small cell lung carcinoma is a rearrangement resulting from an inversion within chromosome 2p leading to the formation of a fusion gene, echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK). Fluorescence in situ hybridization (FISH) is the gold standard for the detection of ALK gene rearrangements. However, molecular methods are not readily available in all pathology laboratories. Immunohistochemistry (IHC) using an antibody directed against the EML4-ALK fusion protein provides a widely available alternative method of detection. We assessed whether IHC is a comparable and cost-effective alternative to FISH analysis for the detection of ALK gene rearrangements. A total of 110 non-small cell lung carcinoma cases (63 surgical/biopsy and 47 cytology specimens), previously tested for ALK gene rearrangements by FISH [7 (6.4%) positive for the rearrangement], were probed for the EML4-ALK fusion protein using a monoclonal EML4-ALK antibody, clone 5A4. Cells were considered to stain positive for ALK if >5% of cells showed cytoplasmic staining of at least grade 1 intensity (scale: 0 to 3). A cost analysis was performed using ALK IHC as a screening test. The sensitivity and specificity of the EML4-ALK IHC stain compared with ALK FISH analysis were 100% and 96%, respectively. All 7 FISH-positive cases stained positive by IHC, whereas 4 FISH-negative cases demonstrated positive staining. One of the 4 FISH-negative, IHC-positive cases harbored an EML4-ALK rearrangement by RT-PCR yielding 3 false-positive results overall. The κ agreement between IHC and FISH methods is 0.76 (substantial/excellent). The potential savings of implementing the ALK IHC as a screening method would be $10,418.21. Sensitivity of the EML4-ALK IHC stain is excellent (100%) but due to its suboptimal specificity, IHC cannot reliably supplant FISH analysis for the detection of ALK gene rearrangements. IHC shows promise as a screening tool to prevent unnecessary costly FISH analysis.