Abstract 6376: Effect of MET tyrosine kinase inhibitors on MET amplified gastro-esophageal cancer cells
Authors: Kim Jin-Soo , Hong Sungyoul , Kim Mi Young 
Published: June 2022

Abstract
Background: Many studies have suggested that MET protein overexpression or MET amplification plays a critical role in the progression of gastro-esophageal cancer (GC) and negatively affects survival in patients with GC. However, the criteria used to define overexpression of MET protein have differed among many studies, and in contrast to the initial phase II studies, the phase III trials failed to show any clinical benefit from anti-MET therapies in GCs, even in patients with MET-positive disease. Several studies have used consistent criteria to define MET amplification on FISH, and recent MET inhibitor trials for MET amplified cancers have been successful. Furthermore, hyperactivation of MET pathway are known to reduce the growth-inhibitory effect of trastuzumab in HER2 positive GC. Currently, there is no FDA approved MET inhibitors for GC. Capmatinib and savolitinib, which are selective MET inhibitors, has been evaluated for various MET positive cancers. The aim of this study was to test these MET inhibitors on MET amplified gastro-esophageal cancer (GC) cells.
Material and Methods: Among a total of 37 GC cells in our lab, the following cells were positive for MET by copy number amplification (CNV &gt; 10): SNU-620, ESO51, MKN-45, SNU-5 and OE-33. We assessed cytotoxic response of these GC cells to capmatinib or savolitinib alone by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay and anchorage independent growth in soft agar. Western blots were performed to assess the cellular activity of capmatinib or savolitinib in MET signal pathway. Xenograft studies were performed to evaluate in vivo therapeutic efficacy of savolitinib with MKN-45 cells.
Results: Savolitinib and capmatinib showed anti-proliferative activity against MET amplified GC cell lines in dose-dependent manner. There was no inhibitory effect on GC cells without MET amplification, such as SNU-216 and SNU-1750. Savolitinib inhibited phosphorylation of MET and down-stream signaling pathway, such as AKT or ERK, in MET amplified GC cells. We observed that treatment with savolitinib induced a significant decrease in the number of colonies formed in soft agar. In addition, Savolitinib exhibited dose-responsive anti-tumor efficacy in xenograft model with MKN-45 GC cells. Furthermore, the combination of Trastuzumab and capmatinib exhibited enhanced inhibition of AKT and ERK activation in OE-33 cells, which is positive for both HER2 and MET, and resistant to trastuzumab alone.
Conclusion: Collectively, these data support that targeting MET with Savolitinib and capmatinib efficiently suppresses the growth of MET amplified GC cells. Moreover, MET inhibitor could synergize with trastuzumab to induce the therapeutic effect on the HER2 and MET amplified GC cells. Further studies are warranted to test this concept in clinical setting.
Citation Format: Jin-Soo Kim, Sungyoul Hong, Mi Young Kim. Effect of MET tyrosine kinase inhibitors on MET amplified gastro-esophageal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6376.