FMS-like tyrosine kinase 3 (FLT3) amplification in patients with metastatic colorectal cancer.

FMS-like tyrosine kinase 3 (FLT3) plays a key role in hematopoiesis. However, the oncogenic role of FLT3 amplification in patients with metastatic colorectal cancer (mCRC) remains unclear. Here, we aimed to evaluate the characteristics, prognosis, and treatment efficacy of an FLT3 inhibitor (regorafenib) in patients with mCRC with FLT3 amplifications. Tumor tissue samples from 2,329 patients were sequenced using next-generation sequencing in the Nationwide Cancer Genome Screening Project in Japan. The effect of clinicopathological features, co-altered genes, prognosis, and efficacy of regorafenib were investigated. Between April 2015 and June 2018, 85 patients with mCRC with FLT3 amplification were observed. There were no differences in baseline characteristics between patients with and without FLT3 amplification. The frequency of RAS or other gene co-alterations was inversely correlated with the copy number status. Median survival time in patients with FLT3 amplification was significantly shorter than in those with non-FLT3 amplification. Further investigations of FLT3 amplification as a potential treatment target in mCRC are warranted. SUPPORTING INFORMATION.