HER2 Blockade in Metastatic Collecting Duct Carcinoma (CDC) of the Kidney: A Case Report

Background: Collecting duct carcinoma of the kidney (CDC) is a rare cancer associated with bad prognosis and, at present, with no specific effective therapies. Case Report: We report a clinical case with disseminated high-grade CDC presenting with widespread metastasis to both lungs, pelvic bones, axial skeleton, and the central nervous system (posterior fossa, both hemispheres and pituitary-hypothalamic). The primary tumor in the kidney was demonstrated (by fluorescence in situ hybridization and immunohistochemistry with Herceptest (3+ score)) to significantly overexpress HER2. Critically ill at presentation, the patient received oral capecitabine together with double HER2 blockade with both intravenous trastuzumab and oral lapatinib. His clinical response was a dramatic improvement and a progressive decline in the radiological size of all of his multiple cancer lesions. Conclusion: Double HER2 blockade is an effective therapy in disseminated CDC even in the presence of brain metastases.