(D) -PPA 1 TFA

(D) -PPA 1 TFA is a stable, hydrolysis-resistant D-peptide antagonist that potently inhibits the PD-1/PD-L1 interaction with a PD-1 affinity of 0.51 μM. It has demonstrated functional activity in cellular assays and shows promise in preclinical models for oncology and immunotherapy research, supporting investigations into immune checkpoint blockade.