It is tempting to speculate that expression profiling of LAG-3, together with PD-1, may be a simple way to enrich for tumor-infiltrating T cells that highly co-express multiple checkpoints and co-stimulators, as has been reported for PD-1high CD8 T cells from NSCLC (18, 48) and ovarian cancer (38). This evidence concerns the gene PDCD1 and ovarian cancer.