In contrast, rhodamine-labeled checkpoint inhibitor antibodies covalently attached to the polymer, P/a-CTLA-4 and P/a-PD-1 (schematics on Fig. 2a bottom) or their combination, were readily detected in the tumor parenchyma 4 h after I.V. injection (Fig. 2a, b bottom row). This evidence concerns the gene CTLA4 and neoplasm.