Identification of Predictive Biomarker of Regorafenib in Refractory Colorectal Cancer

Regorafenib is a multi-tyrosine kinase inhibitor which has been shown to increase survival in metastatic colorectal cancer patients who have progressed after prior standard treatments. Progression-free survival data suggest that there could be a distinct subgroup of patients that may benefit from regorafenib. Therefore, it would be important to identify predictive biomarker of efficacy of regorafenib. Considering that regorafenib is a multi-tyrosine kinase inhibitor, comprehensive approach is required to discover predictive biomarker. NGS-based sequencing allows generating large amount of data regarding multiple genes and multiple genetic alterations within a single experiment. Also, it requires less amount of DNA or tissue and cost compared to currently used individual gene testing techniques such as direct sequencing or FISH. Moreover, superior sensitivity over Sanger sequencing can be obtained by increasing coverage depth, especially in cases with low tumor purity. Wide range of genes targeted by regorafenib and genes in the major oncogenic pathway of colorectal cancer influenced by regorafenib can be efficiently assessed using NGS-based sequencing. The aim of this study is to identify predictive biomarker of efficacy of regorafeinib in metastatic, refractory colorectal cancer patients using NGS technology.