Trastuzumab Rezetecan in Advanced Solid Tumors Refractory to Standard Therapies

This study is a single-center, multi-cohort, phase II clinical trial. Eligible patients with HER2-positive advanced solid tumors were enrolled after providing informed consent. A total of 90 patients were allocated into three cohorts (30 patients each): those with Extramammary Paget's Disease (EMPD), rare solid tumors, or urothelial carcinoma, who had experienced failure of standard treatment or for whom no standard treatment was available. The participant recruitment period was 12 months, and the follow-up duration was 12 months. All patients received Trastuzumab Rezetecan (SHR-A1811) at a dose of 4.8 mg/kg administered every three weeks (q3w). They were followed until disease progression, withdrawal from the study, loss to follow-up, or death, whichever occurred first. Tumor response was assessed radiologically every 6 weeks during treatment. Safety follow-up was conducted 30 days after the last dose, followed by survival follow-up every 3 months thereafter.