Trastuzumab and pertuzumab in circulating tumor DNA ERBB2-amplified HER2-positive refractory cholangiocarcinoma

Cholangiocarcinoma is a heterogeneous and target-rich disease with differences in actionable targets. Intrahepatic and extrahepatic types of cholangiocarcinoma differ significantly in clinical presentation and underlying genetic aberrations. Research has shown that extrahepatic cholangiocarcinoma is more likely to be associated with ERBB2 (HER2) genetic aberrations. Various anti-HER2 clinical trials, case reports and other molecular studies show that HER2 is a real target in cholangiocarcinoma; however, anti-HER2 agents are still not approved for routine administration. Here, we show in a metastatic cholangiocarcinoma with ERBB2 amplification identified on liquid biopsy (circulating tumor DNA (ctDNA) testing), a dramatic response to now over 12 months of dual-anti-HER2 therapy. We also summarize the current literature on anti-HER2 therapy for cholangiocarcinoma. This would likely become another treatment option for this target-rich disease.