Anti-programmed Death Receptor 1 Blockade Induces Clinical Response in a Patient With Metastatic Collecting Duct Carcinoma

Collecting duct carcinoma (CDC) is a very rare subtype of renal cell carcinoma (RCC), accounting for < 2% of all cases of RCC and associated with a very poor prognosis. Treatment of metastatic CDC with immunotherapy, chemotherapy, and targeted therapy (vascular endothelial growth factor pathway-targeted agents, mammalian target of rapamycin inhibitors) has shown limited success. Programmed death 1 (PD-1) is a receptor expressed by activated T-cells that induces immunosuppression by interaction with PD-1 ligand 1, found on tumor cells. Approved PD-1 inhibitors such as nivolumab and pembrolizumab disrupt this immunosuppressive interaction; their use in CDC has not been reported. We report the case of a patient with metastatic CDC treated with nivolumab with progression after chemotherapy and tyrosine kinase inhibitor therapy. She received 3 mg/kg nivolumab intravenously every 3 weeks for 3 months and underwent repeat imaging; the therapy was well tolerated, without side effects. After 3 months of therapy, our patient experienced a partial response of target lesions (46% reduction); the nontarget lesions remained stable, and no new lesions were identified. Nivolumab might show antitumor activity in patients with metastatic CDC or non-clear cell RCC in whom standard therapies have failed; further study is encouraged.