Detection of ALK fusion transcripts in FFPE lung cancer samples by NanoString technology

BACKGROUND ALK-rearranged lung cancers exhibit specific pathologic and clinical features and are responsive to anti-ALK therapies. Therefore, the detection of ALK-rearrangement is fundamental for personalized lung cancer therapy. Recently, new molecular techniques, such as NanoString nCounter, have been developed to detect ALK fusions with more accuracy and sensitivity. METHODS In the present study, we intended to validate a NanoString nCounter ALK-fusion panel in routine biopsies of FFPE lung cancer patients. A total of 43 samples were analyzed, 13 ALK-positive and 30 ALK-negative, as previously detected by FISH and/or immunohistochemistry. RESULTS The NanoString panel detected the presence of the EML4-ALK, KIF5B-ALK and TFG-ALK fusion variants. We observed that all the 13 ALK-positive cases exhibited genetic aberrations by the NanoString methodology. Namely, six cases (46.15%) presented EML-ALK variant 1, two (15.38%) presented EML-ALK variant 2, two (15.38%) presented EML-ALK variant 3a, and three (23.07%) exhibited no variant but presented unbalanced expression between 5'/3' exons, similar to other positive samples. Importantly, for all these analyses, the initial input of RNA was 100 ng, and some cases displayed poor RNA quality measurements. CONCLUSIONS In this study, we reported the great utility of NanoString technology in the assessment of ALK fusions in routine lung biopsies of FFPE specimens.