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Screening of ROS1 rearrangements in lung adenocarcinoma by immunohistochemistry and comparison with ALK rearrangements.

ABSTRACT: ROS1 rearrangement is a predictive biomarker for response to the tyrosine kinase inhibitor, crizotinib. We investigated the usefulness of ROS1 immunohistochemistry (IHC) for the detection of patients who harbor ROS1 rearrangements in two separate cohorts. We also compared ROS1 IHC with ALK IHC in terms of diagnostic performance to predict each gene rearrangement. In a retrospective cohort, IHC was performed in 219 cases of lung adenocarcinoma with already known genetic alterations. In a prospective cohort, we performed IHC for 111 consecutive cases of lung adenocarcinoma and confirmed the results by subsequent FISH. In the retrospective cohort, all 8 ROS1-rearranged tumors were immunoreactive, and 14 of 211 ROS1-wild cases were immunoreactive (sensitivity 100% and specificity 93.4%). In the prospective cohort, all IHC-negative cases were FISH-negative, and 5 of 34 ROS1 immunoreactive cases were ROS1-rearranged (sensitivity 100% and specificity 72.6%). In ROS1-wild tumors, ROS1 protein was more expressed in the tumors of ever-smokers than in those of never-smokers (p = 0.003). ALK IHC showed 100% sensitivity and 98.1 to 100% specificity in both patient cohorts. In conclusion, ROS1 IHC is highly sensitive, but less specific compared with ALK IHC for detection of the corresponding rearrangement. ROS1 IHC-reactive tumors, especially when the tumor is stained with moderate to strong intensity or a diffuse pattern, are recommended to undergo FISH to confirm the gene rearrangement.

SUBMITTER: Cha YJ

PROVIDER: S-EPMC4109990 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:A number of mutations in key oncogenes have been identified as important for the initiation and maintenance of lung adenocarcinoma (LAC). This study elucidated the prevalence and prognostic significance of mutations in the epidermal growth factor receptor gene (EGFR) and rearrangements in the anaplastic lymphoma kinase gene (ALK) in patients with surgically resected primary LAC. PATIENTS AND METHODS:We retrospectively analyzed 675 consecutive patients who underwent radical resection at a single institution. We concurrently analyzed mutations in EGFR and the Kirsten rat sarcoma viral oncogene homolog gene (KRAS) by reverse transcription (RT)-PCR, and investigated ALK rearrangements by immunohistochemistry. LAC with or without various oncogenic mutations was studied for clinicopathological features and their association with disease-free survival (DFS) and overall survival (OS). RESULT:ALK rearrangements and EGFR mutations were detected in 75 and 312 patients, respectively, with coexistence in 5 cases. ALK rearrangements and mutations in EGFR and KRAS were mutually exclusive. Compared with patients with EGFR mutations, ALK rearrangements were more common in younger patients, and those with advanced tumors, lymph node metastases, and higher rates of postoperative adjuvant therapy. Histologically, EGFR mutations were more common than ALK rearrangements in patients with the acinar predominant subtype and the lepidic predominant subtype of LAC, whereas ALK rearrangements were more frequent in the solid predominant subtype with mucin production and invasive mucinous adenocarcinomas. ALK-positive patients had a significantly worse DFS than those with EGFR mutations and wild-type (WT) patients. The mean OS after surgical procedures was significantly longer in EGFR-mutated versus WT patients. No significant differences were found in patients with ALK-positive tumors compared with EGFR-mutated and WT patients. CONCLUSION:Clinicopathological features of LAC with ALK rearrangements differ from those of LAC with EGFR mutations. Patients with ALK rearrangements had a significantly worse DFS than those harboring EGFR mutations. Thus, ALK rearrangements are an adverse prognostic factor in surgically-resected LAC patients, while EGFR mutations are associated with a better prognosis.

Project description:IntroductionTargeted somatic genomic analysis (EGFR, anaplastic lymphoma receptor tyrosine kinase gene [ALK], and ROS1) and programmed death ligand 1 (PD-L1) tumor proportion score (TPS) determined by immunohistochemistry (IHC) are used for selection of first-line therapies in advanced lung cancer; however, the frequency of overlap of these biomarkers in routine clinical practice is poorly reported.MethodsWe retrospectively probed the first 71 pairs of patients with lung adenocarcinoma from our institution. They were analyzed for PD-L1 by IHC using the clone 22C3 pharmDx kit (Agilent Technologies, Santa Clara, CA) and evaluated for co-occurrence of genomic aberrations and clinicopathologic characteristics.ResultsSurgical resection specimens, small biopsy (transbronchial or core needle) samples, and cytologic cell blocks (needle aspirates or pleural fluid) were tested. A PD-L1 TPS of at least ≥50% was seen in 29.6% of tumors. Of 19 tumors with EGFR mutations, ALK fluorescence in situ hybridization positivity, or ROS1 fluorescence in situ hybridization positivity, 18 had a PD-L1 TPS less than 50% versus only one tumor with a PD-L1 TPS of at least 50% (p = 0.0073). Tumors with a PD-L1 TPS of at least 50% were significantly associated with smoking status compared with tumors with a PD-L1 TPS less than 50% but were not associated with patient sex, ethnicity, tumor stage, biopsy site, or biopsy type/preparation.ConclusionsPD-L1 IHC can be performed on routine clinical lung cancer specimens. A TPS of at least 50% seldom overlaps with presence of driver oncogenes with approved targeted therapies. Three biomarker-specified groups of advanced lung adenocarcinomas can now be defined, each paired with a specific palliative first-line systemic therapy of proven clinical benefit: (1) EGFR/ALK/ROS1-affected adenocarcinoma paired with a matched tyrosine kinase inhibitor (∼20% of cases), (2) PD-L1-enriched adenocarcinoma (TPS ≥50%) paired with anti-PD-1 pembrolizumab (∼30% of cases), and (3) biomarker-negative (i.e., EGFR/ALK/ROS1/PD-L1-negative) adenocarcinoma paired with platinum doublet chemotherapy with or without bevacizumab (∼50% of cases).

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Screening of ROS1 rearrangements in lung adenocarcinoma by immunohistochemistry and comparison with ALK rearrangements.

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