Core Viewpoint - CAR-T cell therapy has shown transformative success in hematological malignancies but faces challenges in solid tumors due to immunosuppressive tumor microenvironments and antigen heterogeneity [3][7]. Group 1: Challenges in CAR-T Cell Therapy - The main challenges in treating solid tumors with CAR-T cell therapy include the immunosuppressive tumor microenvironment and antigen expression heterogeneity [7]. - Antigen loss or escape during treatment often leads to off-target effects and resistance to CAR-T cells [3]. Group 2: Innovative Solutions - A research team from Harbin Medical University developed a platform called BROAD-CAR, which utilizes engineered outer membrane vesicles (OMV) to enhance CAR-T cell therapy for solid tumors [4][9]. - OMV can induce strong immune responses and alter the immunosuppressive tumor microenvironment without the risks associated with live bacteria [7]. Group 3: Mechanism and Efficacy - The BROAD-CAR platform enhances CAR-T cell anti-tumor activity by blocking the PD-1/PD-L1 signaling pathway, improving CAR-T cell expansion, and facilitating in situ antigen modification [9]. - In mouse models of breast cancer, BROAD-CAR has been shown to inhibit tumor recurrence and metastasis [9]. Group 4: Overall Implications - This research presents a safe and effective method to enhance the efficacy and applicability of CAR-T cell therapy in solid tumors [11].