Long term response on Regorafenib in non-V600E BRAF mutated colon cancer: a case report

Abstract

Background: ^Non-V600E BRAF mutated colorectal cancer (CRC) is a rare disease entity with specific clinical features. These tumors are less likely to have microsatellite instability than CRC with a V600E BRAF mutation and often harbor a KRAS or NRAS mutation. Notably, median overall survival is longer than in wild-type BRAF CRC. Little is known about treatment possibilities in these patients.

Case presentation: We present the case of a 59 year old patient with a rare mutation in BRAF codon 594, who progressed rapidly on all classical therapies but experienced a clear and long lasting response on treatment with Regorafenib.

Conclusion: Little is known about therapies that can be effective in the rare ^non-V600E BRAF mutated CRCs. We present a patient who had a definite response to treatment with Regorafenib. There are no predictive markers that define a subset of CRC patients who benefit most from Regorafenib. The specific features of this ^non-V600E BRAF mutated CRC may be relevant in the exploration of predictive biomarkers for the efficacy of Regorafenib.

Keywords: Case report; Colon cancer; Epithelial to mesenchymal transition; Non-V600E BRAF mutation; Regorafenib.