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O04 - Molecular Pathology I (ID 126)
- Event: WCLC 2013
- Type: Oral Abstract Session
- Track: Pathology
- Presentations: 1
- Moderators:I.I. Wistuba, W.A. Cooper
- Coordinates: 10/28/2013, 10:30 - 12:00, Parkside Ballroom A, Level 1
O04.01 - Identification of CD74-NRG1, a new recurrent fusion gene in invasive mucinous lung adenocarcinomas of never smokers (ID 4022)
10:30 - 12:00 | Author(s): E. Stoelben
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.
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.
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
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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P3.12 - Poster Session 3 - NSCLC Early Stage (ID 206)
- Event: WCLC 2013
- Type: Poster Session
- Track: Medical Oncology
- Presentations: 1
- Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
P3.12-023 - International Tailored Chemotherapy Adjuvant Trial: ITACA Trial (ID 1452)
09:30 - 16:30 | Author(s): E. Stoelben
This is an ongoing phase III multicenter randomized trial comparing adjuvant pharmacogenomic-driven chemotherapy, based on thymidilate synthase (TS) and excision-repair cross-complementing-1 (ERCC1) gene expression versus standard adjuvant chemotherapy in completely resected Stage II-IIIA non-small cell lung cancer (EudraCT #: 2008-001764-36).
For all the registered patients (pts) the expression of ERCC1 and TS is assessed by qRT-PCR on paraffin-embedded tumor specimens in a central laboratory. Randomization is stratified by stage and smoking status. Trial was emended on Feb, 2011 with the 7th staging system. Primary end point is overall survival; secondary end points include recurrence-free survival, therapeutic compliance, toxicity profile and comparative evaluation of ERCC1 and TS mRNA versus protein expression. It is assumed that the 5-year survival rate in the control arm is 45% and the hazard reduction associated to the experimental treatment is 30%. With a power of 90% to detect the estimated effect with log-rank test, a significant level of 5% (2 tails), 336 events have to be observed; the expected total number of pts is 700. The final statistical analysis will compare all pts in the control arms versus all those treated in the tailored chemotherapies groups. Efficacy analysis will be done on an intent-to-treat basis. Cox proportional hazard model will be used for estimating hazard ratios after adjusting for relevant variables. Within 45 days post-surgery, pts in each genetic profile are randomized to receive either a standard chemotherapy selected by the investigator (cisplatin/vinorelbine, cisplatin/docetaxel or cisplatin/gemcitabine) or an experimental treatment (tailored arms) selected as follows: 1) high ERCC1 and high TS 4 cycles of single agent paclitaxel 2) high ERCC1 and low TS 4 cycles of single agent pemetrexed 3) low ERCC1 and high TS 4 cycles of cisplatin/gemcitabine 4) low ERCC1 and low TS 4 cycles of cisplatin/pemetrexed. All chemotherapy regimens are administered for a total of 4 cycles on a 3-weekly basis.
Currently, 558 pts have been randomized from 26 institutions mainly located in Italy and Germany (average enrolment: 19 patients/month). This is one of the pharmacogenomic-driven trial in the adjuvant setting in the European scenario.