Efficacy and Safety of Disitamab Vedotin (RC48) in Combination With Bevacizumab or Pyrotinib in Patients With HER2-Positive Metastatic Breast Cancer After Trastuzumab Deruxtecan (T-DXd) Treatment Failure: A Phase II Study
This multicenter, Phase II study (RADIANT-BC01) evaluates the efficacy and safety of Disitamab Vedotin (RC48) in combination with either bevacizumab or pyrotinib in adult patients with HER2-positive metastatic breast cancer whose disease has progressed on prior trastuzumab deruxtecan (T-Dxd) therapy. Eligible participants will be randomized 1:1 to receive RC48 plus bevacizumab (7.5 mg/kg IV every 2 weeks) or RC48 plus pyrotinib (320 mg orally once daily). Treatment continues until disease progression, unacceptable toxicity, withdrawal of consent, or initiation of new anticancer therapy. The primary endpoint is objective response rate (ORR); key secondary endpoints include progression-free survival (PFS), disease control rate (DCR), duration of response (DOR), overall survival (OS), and safety. This study aims to identify new post-T-Dxd treatment options and improve outcomes for patients with advanced HER2-positive breast cancer.
• Age ≥18 years.
• Histologically or cytologically confirmed HER2-positive (IHC 3+ or IHC 2+ with ISH amplification) advanced or metastatic breast cancer.
• Prior treatment with trastuzumab deruxtecan (T-DXd) and documented disease progression during or after therapy.
• At least one measurable lesion at baseline as defined by RECIST v1.1.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
• Adequate organ and marrow function, including:
⁃ Absolute neutrophil count ≥1.5 × 10⁹/L Platelet count ≥100 × 10⁹/L Hemoglobin ≥9 g/dL ALT and AST ≤2.5 × ULN Total bilirubin ≤1.5 × ULN Creatinine clearance ≥50 mL/min Estimated life expectancy of ≥12 weeks. Ability to understand and willingness to sign a written informed consent form.