Possibilities of therapeutic use of HER2-inhibitorsin metastatic colorectal cancer: a case report

Abstract

Current landscape of personalized and molecular-driven approach to cancer treatment contributes to a rapid growth of novel biomarkers used for a targeted therapy. Amplification or over-expression of HER2 has been shown to play an important role in the development and progression of some cancers. Recent studies have shown that over-expression of HER2 is found in up to 5% of colorectal cancers (CRC). These findings led to active research of therapeutic use of HER2-targeted therapy in a subset of patients with metastatic CRC, especially in patients with wild-type RAS, who progressed on anti-EGFR targeted therapy. According to data from several published studies, the rate of objective responses, progression-free and overall survival in this subset of patients matches or exceeds same rates that are achieved while using BRAF-targeted therapies in BRAF-mutated metastatic CRC patients and immunotherapy used in subjects diagnosed with MSI-H tumors. Currently, there is no conclusive data on potential of HER2-targeted therapy in RAS-mutated CRC patients. In this paper, we report a case of durable objective response obtained on trastuzumab therapy in patient with metastatic CRC, mutation in 12 th exon of KRAS gene and over-expression of HER2 in 40% of tumor cells, after progression on several lines of chemotherapy and anti-angiogenic targeted therapy.