Gastrointestinal malignancies harbor actionable MET exon 14 deletions
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Jeeyun Lee1,2,*, Sai-Hong Ignatius Ou3,*, Ji Min Lee4,*, Hee Cheol Kim5,*, Mineui Hong6, Sun Young Kim1, Jiryeon Jang1, Soomin Ahn6, So Young Kang6, Sujin Lee1, Seung Tae Kim1, Bogyou Kim4, Jaehyun Choi4, Kyung-Ah Kim4, Jiyun Lee1, Charny Park1,6, Se Hoon Park1, Joon Oh Park1,2, Ho Yeong Lim1, Won Ki Kang1, Keunchil Park1,2, Young Suk Park1, Kyoung-Mee Kim2,6
1Department of Medicine, Division of Hematology-Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
2Innovative Cancer Medicine Institute, Samsung Medical Center, Seoul, Republic of Korea
3Chao Family Comprehensive Cancer Center, University of California Irvine School of Medicine, Orange, California, USA
4Samsung Biomedical Research Institute, Samsung Advanced Institute of Technology (SAIT)/Samsung Electronics Co. Ltd, Yeongtong-gu, Suwon-si, Gyeonggi-do, Korea
5Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
6Department of Pathology and Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
*These authors have contributed equally to this work
Young Suk Park, e-mail: firstname.lastname@example.org
Keunchil Park, e-mail: email@example.com
Kyoung-Mee Kim, e-mail: firstname.lastname@example.org
Keywords: MET exon 14 skipping, colorectal carcinoma, MET monoclonal antibodies, crizotinib, gastrointestinal malignancies
Received: May 19, 2015 Accepted: August 31, 2015 Published: September 10, 2015
Recently, MET exon 14 deletion (METex14del) has been postulated to be one potential mechanism for MET protein overexpression. We screened for the presence of METex14del transcript by multiplexed fusion transcript analysis using nCounter assay followed by confirmation with quantitative reverse transcription PCR with correlation to MET protein expression by immunohistochemistry (IHC) and MET amplification by fluorescence in situ hybridization (FISH). We extracted RNAs from 230 patients enrolled onto the prospective molecular profiling clinical trial (NEXT-1) (NCT02141152) between November 2013 and August 2014. Thirteen METex14del cases were identified including 3 gastric cancer, 4 colon cancer, 5 non-small cell lung cancer, and one adenocarcinoma of unknown primary. Of these 13 METex14del cases, 11 were MET IHC 3+ and 2 were 2+. Only one out of the 13 METex14del cases was MET amplified (MET/CEP ratio > 2.0). Growths of two (gastric, colon) METex14del+ patient tumor derived cell lines were profoundly inhibited by both MET tyrosine kinase inhibitors and a monoclonal antibody targeting MET. In conclusion, METex14del is a unique molecular aberration present in gastrointestinal (GI) malignancies corresponding with overexpression of MET protein but rarely with MET amplification. Substantial growth inhibition of METex14del+ patient tumor derived cell lines by several MET targeting drugs strongly suggests METex14del is a potential actionable driver mutation in GI malignancies.
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