Efficacy and Safety of PD-L1 Monoclonal Antibody Combined With Metronomic VEX in Advanced Triple-negative Breast Cancer

In recent years, immune therapy has significantly altered the treatment landscape for various malignant tumors, including breast cancer. Apart from its direct cytotoxic effects on tumor cells, metronomic chemotherapy has the potential to modulate the immune microenvironment, thereby demonstrating substantial synergistic potential with immune therapy. In a previous prospective adaptive randomized phase II clinical trial, we identified a promising regimen involving PD-1 monoclonal antibody in combination with vinorelbine + cyclophosphamide + capecitabine (VEX) metronomic chemotherapy. Building on this foundation, we plan to conduct a multicenter, randomized, controlled phase II study to evaluate the efficacy and safety of the PD-L1 monoclonal antibody in combination with VEX metronomic chemotherapy for patients with advanced triple-negative breast cancer, aiming to provide crucial evidence to guide medication for patients in advanced stages. The control group will receive metronomic oral vinorelbine 20 mg every other day + cyclophosphamide 50 mg daily + capecitabine 500 mg three times daily. The experimental group will receive additional PD-L1 inhibitor adebrelimab at a dose of 1200 mg via intravenous infusion every three weeks. Each cycle consists of three weeks, with imaging examinations conducted every six weeks (two cycles) to assess treatment efficacy. Subjects will continue medication until imaging indicates disease progression, toxicity becomes intolerable, withdrawal of informed consent, or the investigator deems it necessary to terminate medication. Evaluation will include efficacy indicators such as median progression-free survival, safety indicators like drug-related adverse reactions, patient survival quality, along with an exploratory analysis of biomarkers potentially associated with efficacy.