STAT3 and chronic hepatitis B virus infection: Thymosin was originally used as an immunomodulatory agent in the treatment of chronic hepatitis B and has been confirmed to significantly inhibit migration and invasion of PD-L1 high expressing NSCLC cells via downregulation of the STAT3-MMP2 signaling pathway compared to PD-L1 low expressing NSCLC cells as evidenced by a prior study [20].