This invention discloses a PBP
peptide that specifically binds to PD-1, its
screening method, and its applications. The PBP
peptide has the sequence shown in SEQ ID No. 1. This invention uses bacterial
surface display technology to screen for PD-1-targeting PBP peptides. These peptides specifically bind to PD-1, exhibit cross-reactivity with human and mouse PD-1, and can competitively bind to PD-1 with PD-L1, effectively blocking the interaction between PD-1 and PD-L1, reversing the function of exhausted T cells, and exerting an anti-tumor effect. Compared to antibodies, the PBP
peptide obtained in this invention has a small molecular weight, strong penetration ability at tumor sites, low production cost, simple preparation process, and does not cause serious immune-related side effects. While achieving corresponding therapeutic effects, it avoids the disadvantages of
antibody drugs, providing a low-molecular-weight candidate
drug for tumor
immunotherapy.