NanoString nCounter analyses showed that intra-tumoral gene expression levels encoding T cell exhaustion markers (that is, LAG-3, TIGIT, CTLA-4 and PD-1) and immunosuppressive markers, including arginase (for which serum levels were negatively correlated with clinical response), were relatively higher in biopsy from Patient 4 (on-treatment greater than baseline) compared with SS samples (Fig. 4c). This evidence concerns the gene PDCD1 and synovial sarcoma.