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D. Lin
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MINI 10 - ALK and EGFR (ID 105)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:T. Yap, T. Li
- Coordinates: 9/07/2015, 16:45 - 18:15, Mile High Ballroom 1a-1f
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MINI10.02 - Intratumoral Heterogeneity of ALK-Rearranged and ALK/EGFR Co-Altered Lung Adenocarcinoma (ID 685)
16:50 - 16:55 | Author(s): D. Lin
- Abstract
- Presentation
Background:
Genetic intratumoral heterogeneity has a profound influence on the selection of clinical treatment strategies and addressing resistance to targeted therapy. The purpose of our study is to explore the potential effect of intratumoral heterogeneity on both the genetic and pathologic characteristics of ALK-rearranged lung adenocarcinoma (LADC).
Methods:
We tested ALK fusions and EGFR mutations in 629 LADC patients by using laser capture microdissection (LCM) to capture spatially separated tumor cell subpopulations in various adenocarcinoma subtypes and test for ALK fusions and EGFR mutations in ALK-rearranged, EGFR-mutated, and ALK/EGFR co-altered LADCs in order to compare the oncogenic driver status between different tumor cell subpopulations in the same primary tumor.
Results:
Among the 629 patients, 30 (4.8%) had ALK fusions, 364 (57.9%) had EGFR mutations, and 2 had ALK fusions coexisting with EGFR mutations. Intratumoral heterogeneity of ALK fusions was identified in 9 patients by RT-PCR. In the 2 ALK/EGFR co-altered patients, intratumoral genetic heterogeneity was observed both between different growth patterns and within the same growth pattern. Genetic intratumoral heterogeneity of EGFR mutations was also identified in EGFR-mutated NSCLC. ALK fusions were positively associated with a micropapillary pattern (P=0.002) and negatively associated with a lepidic pattern (P=0.008) in a statistically-expanded analysis of 900 individual adenocarcinoma components, although they appeared to be more common in acinar-predominant LADCs in the analysis of 629 patients.
Conclusion:
Intratumoral genetic heterogeneity was demonstrated to co-exist with histologic heterogeneity in both single-driver and EGFR/ALK co-altered LADCs. As for the latter, one of the dual altered drivers may be the trunk-driver for the tumor.
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