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T. Zander



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    MO10 - Molecular Pathology II (ID 127)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track: Pathology
    • Presentations: 1
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      MO10.04 - High throughput parallel amplicon sequencing of common driver mutations from FFPE lung cancer samples in molecular pathological routine diagnostics for a regional health care provider network (ID 2145)

      16:30 - 16:35  |  Author(s): T. Zander

      • Abstract
      • Presentation
      • Slides

      Background
      Treatment paradigms for non–small-cell lung cancer (NSCLC) have shifted from one based only on histology to one that incorporates molecular subtypes involving particular genetic alterations such as activating mutations in EGFR or translocations of ALK. The list of therapeutically targetable lesions is rapidly increasing including mutations in genes such as EGFR, HER2, KRAS, ALK, BRAF, PIK3CA, AKT1, ROS1, NRAS, FGFR1 and MAP2K1. Analysis of these potential targets is becoming a challenge in terms of work load, tissue availability as well as cost. Within the Network Genomic Medicine Lung Cancer (NGM), a regional molecular screening network of the Center for Integrated Oncology Köln Bonn, we aimed to improve on the sequential analysis of a set of 9 target amplicons by Sanger sequencing using bench top ultra-deep parallel sequencing platforms. We aimed to reduce 1) the time requirement for comprehensive molecular diagnostics, 2) the minimal amount of formalin fixed paraffin embedded (FFPE) derived input DNA, 3) while at the same time increasing the number of target regions analysed.

      Methods
      We established a multiplex PCR to amplify up to 640 lung cancer relevant target regions from at least 20ng of FFPE derived tumor DNA. The amplicon libraries were ligated to adapters encompassing medical identifier sequences that allowed multiplexing of up to 48 patients. The resulting libraries were sequenced on a benchtop Illumina platform (MiSeq). Mutations identified by parallel sequencing were confirmed by Sanger sequencing.

      Results
      330 patients were analyzed both by traditional single PCR based Sanger sequencing of 9 amplicons and the newly established parallel sequencing protocol. We found that the NGS approach worked reliably, was less prone to sequencing analysis errors and that the time needed to complete the mutation screening was significantly reduced to 7 working days from previously 21 days. A total of at least 300ng of DNA was needed to complete the analysis of 9 amplicons by Sanger sequencing compared to 20 to 100ng of DNA needed for up to 640 amplicons analyzed by parallel sequencing.

      Conclusion
      Newly multiplex PCR based parallel sequencing allows rapid comprehensive mutation testing in routine molecular pathological diagnostics even on small FFPE embedded transbronchial biopsies.

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    O04 - Molecular Pathology I (ID 126)

    • Event: WCLC 2013
    • Type: Oral Abstract Session
    • Track: Pathology
    • Presentations: 1
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      O04.01 - Identification of CD74-NRG1, a new recurrent fusion gene in invasive mucinous lung adenocarcinomas of never smokers (ID 4022)

      10:30 - 10:40  |  Author(s): T. Zander

      • Abstract
      • Presentation
      • Slides

      Background
      Lung adenocarcinoma (AD) of patients who have never smoked frequently bear targetable genome kinase alterations, such as EGFR mutations and translocations affecting ALK, ROS1, and RET genes. These mutations correlate with kinase inhibitor sensitivity in mouse models or in patients. Unfortunately, therapeutically relevant kinase alterations are not present in all lung cancer specimens. Thus, additional genome alterations need to be discovered in order to provide a therapeutic opportunity for the remaining patients.

      Methods
      We collected a cohort of 25 AD specimens of never smokers lacking mutations in KRAS or EGFR, in which we performed transcriptome sequencing with the aim of identifying new oncogenic driver genes.

      Results
      We were able to identify known kinase fusions affecting ALK, ROS1 and RET genes in 3 cases each. Moreover, we detected one sample carrying a novel chimeric transcript fusing the first six exons of CD74 to the EGF-like domain of the NRG1 III-β3 isoform, leading to the expression of its EGF-like domain in an otherwise NRG1-negative tumor tissue. The fusion gene was further detected in four additional cases out of 94 pan-negative* ADs of never smokers. In total, all 5 cases were identified in stage I invasive mucinous lung adenocarcinomas (IMA) of never smoker females. This tumor type frequently presents with multifocal unresectable disease, for which no effective treatment has been yet established. IMA is highly associated with KRAS mutations; indeed, out of 15 IMA analysed, 6 carried a KRAS mutation (40%), and 4 the CD74-NRG1 fusion (27%). Given the fact that NRG1 signals through ERBB3 and ERBB4 receptors, we aimed to determine which receptor CD74-NRG1 provides the ligand for. We observed that ERBB4 was not expressed in the index case, while ERBB3 was relatively highly expressed and this expression also correlated with a positive phospho-ERBB3 (p-ERBB3) signal in the tumoral tissue of all 5 CD74-NRG1 positive cases. In order to test if this phosphorylation of ERBB3 was statistically significant, we stained a cohort of 241 ADs and found that p-ERBB3 was only positive in 6 of them (p-value<0.0001). Additionally, although both EGFR and ERBB2 were expressed in the index case, only ERBB2 expression correlated with a p-ERBB2 positive signal. These data suggest that CD74-NRG1 might provide the ligand for ERBB3, which may form heterodimers with ERBB2, since ERBB3 is devoid of intrinsic kinase activity and cannot support linear signaling in isolation. This is in line with previous studies showing that NRG1 induces an oncogenic signal through ERBB2-ERBB3 heterodimers engaging the PI3K-AKT pathway. This was further supported by the activation of the PI3K-AKT, but not the MAPK pathway, in CD74-NRG1 transduced H2052 lung cells, after 24h starvation. *pan-negative: EGFR, KRAS, ALK, HER2, BRAF, ROS1 and RET wild-type

      Conclusion
      Altogether, these data shows that CD74-NRG1 is a new recurrent oncogenic fusion gene, highly associated with IMA of never smokers. It also suggests that CD74-NRG1 fusion protein signals through the ERBB2-ERBB3 receptors complex leading to the activation of the PI3K-AKT pathway, providing a therapeutic opportunity for a tumor type with, so far, no effective treatment.

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