Prolonged response of widely metastatic HER2-positive colon cancer to trastuzumab therapy

Abstract

Emerging evidence suggests a small subset of late-stage colon cancer driven by HER2, a biomarker routinely evaluated in select breast and gastric cancers, may respond to HER2-targeted therapy. Herein, we describe a 49-year-old male with widely metastatic colon cancer originating in the sigmoid colon. After failing standard therapy, a biopsy specimen of the tumor was evaluated for novel biomarkers using molecular profiling. After identification of ERBB2 (HER2) amplification using in situ hybridization, the patient subsequently received a trial of trastuzumab monotherapy and experienced a dramatic and durable response. This report builds on our understanding of using precision oncology to improve survival in metastatic colon cancer.