Author of

• 12592

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  P3.10 - Poster Session 3 - Chemotherapy (ID 210)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Medical Oncology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 12627

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    P3.10-035 - Usefulness of IHC for detection of the ALK-fusion gene in non-small cell lung cancer (ID 2122)

    09:30 - 09:30  |  Author(s): E. Sugiyama
    • Abstract

    Background
    Diagnostic guidelines on CAP-IASLC-AMP recommend the use of the ALK fluorescence in situ hybridization (FISH) assay for selecting suitable patients for ALK-TKI therapy. However, based on some reports of the usefulness of immunohistochemistry (IHC) for the detection of ALK, it was considered that it may be possible to use IHC instead of FISH, which is more time-consuming and technically difficult, for the select suitable patients for ALK-TKI therapy in FFPE specimens. The purpose of this study was to investigate the usefulness of IHC as compared to FISH for the diagnosis of ALK-fusion gene-positive NSCLC in clinical practice.

    Methods
    A total of 52 patients with NSCLC who were examined for the ALK-fusion gene by both IHC (Envision Flex+, Dako) and FISH (break-apart probe) at the National Cancer Center Hospital East from March 2012 to March 2013 were included in this study. The reliability and usefulness of IHC as compared to those of FISH were examined for the diagnosis of ALK-fusion gene-positive NSCLC.

    Results
    There were 26 men and 26 women, with a median age 63 years (range, 25-78 years). The pathological diagnosis, based on the examination of 20 resected specimens and 32 biopsy specimens, was adenocarcinoma in 47 cases and poorly-differentiated NSCLC in the remaining 5 cases. ALK protein overexpression was detected by IHC in 11 patients, in contrast, ALK rearrangement was detected by FISH in 9 patients. When the results of the FISH assay were considered as true-positive, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of IHC were 78%, 100%, 74%, 64%, and 93%, respectively. There were 7 patients with discordant ALK status, consisting of 2 patients who were IHC-negative/ FISH-positive, 4 patients who were IHC-positive/ FISH-indeterminate and 1 patient who was IHC-negative/FISH-indeterminate. Of these patients with discordant ALK status, three received ALK-TKI (crizotinib) therapy. The best response rate according to assessment by the RECIST was SD in the patient who was IHC-negative/ FISH-positive, and PR in both the patients who were IHC-positive / FISH-indeterminate. Figure 1

    Conclusion
    Although the ALK-true positive result remained unclear, based on the responses to crizotinib, it might be judged that the result was true-positive in the patients who were IHC-positive/ FISH-indeterminate and true-negative in the patient who was IHC-negative/ FISH-positive. Thus, it appeared that FISH could not determine the ALK status in approximately 10% of the patients, and it can therefore not be considered an absolute diagnostic method.