PDCD1 and neoplasm: To ensure that differences observed between LA and HA CAR-T cells upon PD-1 ablation were not due to intrinsic changes in tumor cells derived from differential expression of PD-L1, we utilized a supported lipid bilayer system (SLB) functionalized with the intercellular adhesion molecule 1 (ICAM-1) to facilitate cell attachment, HER2 for CAR recognition and PD-L1 at titrated densities (Fig. 3a)22,23.