Trastuzumab Rezetecan in Advanced Solid Tumors Refractory to Standard Therapies: A Multicenter, Single-Arm, Phase II Study With Multiple Cohorts
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.
• Voluntarily sign a written informed consent form.
• Age ≥ 18 years.
• Diagnosed with the corresponding advanced tumor confirmed by histology and/or cytology, combined with imaging or ultrasound assessment, and pathologically confirmed as HER2-positive (i.e., HER2 ≥ 1+ by immunohistochemistry \[IHC\]).
• Cohort 1 only: Histologically confirmed extramammary Paget's disease (EMPD) with unresectable locally advanced or metastatic disease.
• Cohort 2 only: Histologically confirmed locally advanced or metastatic rare solid tumor (e.g., sarcoma, urachal cancer) refractory to standard treatment or for whom no standard treatment is available.
• Cohort 3 only: Histologically confirmed locally advanced or metastatic urothelial carcinoma with disease progression following first-line treatment with a PD-1/PD-L1 inhibitor combined with enfortumab vedotin or disitamab vedotin.
• ECOG Performance Status: 0 to 2.
• At least one measurable lesion (according to RECIST v1.1 criteria: non-nodal lesions with longest diameter ≥10 mm on CT scan, nodal lesions with short axis ≥15 mm on CT scan).
• Hematological function:
• Absolute Neutrophil Count (ANC) ≥ 1.5 × 10⁹/L
• Platelet count (PLT) ≥ 70 × 10⁹/L
• Hemoglobin (HGB) ≥ 80 g/L
• Hepatic function:
• Serum total bilirubin (TBIL) ≤ 1.5 × Upper Limit of Normal (ULN)
• Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) ≤ 3 × ULN (≤ 5 × ULN if liver metastases are present)
• Serum albumin ≥ 28 g/L
• Renal function:
• Serum creatinine (Cr) ≤ 1.5 × ULN or Creatinine clearance ≥ 50 mL/min (calculated using the standard Cockcroft-Gault formula)
• Coagulation function:
• International Normalized Ratio (INR) ≤ 1.5 and/or Prothrombin Time (PT) ≤ 1.5 × ULN
• Activated Partial Thromboplastin Time (aPTT) ≤ 1.5 × ULN
• Estimated life expectancy ≥ 3 months.
• Use of medically approved contraception during the treatment period and for at least 120 days after the end of the study; sperm donation or cryopreservation for fertilization purposes is not allowed during this period.
• Ability to comply with the study visit schedule and other protocol requirements.