MSLN and neoplasm: Upon intravenous administration into murine tumor models, including colorectal cancer (MC38), mesothelin‐expressing colon adenocarcinoma (CT26‐MSLN), and melanoma (B16F10), the engineered bacteria effectively alleviated PD‐L1–mediated suppression of CD8+ cytotoxic T lymphocytes within the tumor microenvironment, thereby significantly inhibiting tumor growth.