Open AccessDetection of an ALK Fusion in Colorectal Carcinoma by Hybrid Capture‐Based Assay of Circulating Tumor DNA
Author(s) -
Lai Andrea Z.,
Schrock Alexa B.,
Erlich Rachel L.,
Ross Jeffrey S.,
Miller Vincent A.,
Yakirevich Evgeny,
Ali Siraj M.,
Braiteh Fadi
Publication year - 2017
Publication title -
the oncologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.176
H-Index - 164
eISSN - 1549-490X
pISSN - 1083-7159
DOI - 10.1634/theoncologist.2016-0376
Subject(s) - kras , neuroblastoma ras viral oncogene homolog , immunohistochemistry , colorectal cancer , microsatellite instability , cancer research , molecular inversion probe , fusion gene , biology , pathology , cancer , medicine , microsatellite , gene , genetics , genotyping , genotype , allele
ALK rearrangements have been observed in 0.05%–2.5% of patients with colorectal cancers (CRCs) and are predicted to be oncogenic drivers largely mutually exclusive of KRAS, NRAS, or BRAF alterations. Here we present the case of a patient with metastatic CRC who was treatment naïve at the time of molecular testing. Initial ALK immunohistochemistry (IHC) staining was negative, but parallel genomic profiling of both circulating tumor DNA (ctDNA) and tissue using similar hybrid capture‐based assays each identified an identical STRN‐ALK fusion. Subsequent ALK IHC staining of the same specimens was positive, suggesting that the initial result was a false negative. This report is the first instance of an ALK fusion in CRC detected using a ctDNA assay. Key Points Current guidelines for colorectal cancer (CRC) only recommend genomic assessment of KRAS, NRAS, BRAF, and microsatellite instability (MSI) status. ALK rearrangements are rare in CRC, but patients with activating ALK fusions have responded to targeted therapies ALK rearrangements can be detected by genomic profiling of ctDNA from blood or tissue, and this methodology may be informative in cases where immunohistochemistry (IHC) or other standard testing is negative.