IL21 and cancer: Next, to investigate the expression and distribution characteristics of IL-21, IgG, and TLS in the tumor microenvironment, we performed mIHC on 30 surgical tumor tissues following neoadjuvant chemoimmunotherapy and identified more CD4+IL21+ and IgG-positive cells in MPR tumor tissues (Fig. 3H, I, Supplementary Fig. S3), while there was no difference in nearest non-cancer tissues (N), and LNs.