PDCD1 and neoplasm: Indeed, our observation of ‘highly correlated’ and ‘non-correlated’ anti-PD1 responder biopsies containing disparate amounts of tumor stroma highlight how lack of sufficient stroma in tumor biopsies likely undermined the statistical robustness of the correlations between fucosylated HLA-DRB1 and CD4+ T cells (Extended Data Fig. 6d).