Phase II study of a trastuzumab biosimilar in combination with paclitaxel for HER2-positive recurrent or metastatic urothelial carcinoma: KCSG GU18-18

•HER2 is a widely explored therapeutic target in solid tumors.•Efficacy and safety of trastuzumab-pkrb + paclitaxel in HER2-positive recurrent or metastatic UC were tested.•The ORR was 48.1% and the duration of response was 6.9 months.•The common TRAEs were peripheral neuropathy, neutropenia, thrombocytopenia, and anemia.•Trastuzumab-pkrb + paclitaxel demonstrates promising efficacy with manageable toxicity profiles.