Peptide Blocking of PD-1/PD-L1 Interaction for Cancer Immunotherapy

Abstract

Immunotherapy has become a promising alternative therapeutic approach for cancer patients. Interruption of immune checkpoints, such as CTLA-4 and PD-1, has been verified to be a successful means for cancer therapy in clinical trials. mAb targeting PD-L1 has been approved to treat urothelial carcinoma, non-small cell lung cancer, or Merkel cell carcinoma by the FDA. However, the high cost of the antibody can limit its application. In our study, targeting PD-L1 peptide (TPP-1), which specifically binds to PD-L1 with high affinity, was identified through bacterial surface display methods. Using a T-cell activation assay and mixed lymphocyte reaction, TPP-1 was verified to interfere with the interaction of PD-1/PD-L1. To examine the inhibitory effect of TPP-1 on tumor growth , a xenograft mouse model using H460 cells was established. The growth rate of tumor masses in TPP-1 or PD-L1 antibody-treated mice was 56% or 71% lower than that in control peptide-treated mice, respectively, indicating that TPP-1 inhibits, or at least retards, tumor growth. IHC of the tumors showed that IFNγ and granzyme B expression increased in the TPP-1 or PD-L1 antibody-treated groups, indicating that TPP-1 attenuates the inhibitory effect of PD-L1 on T cells and that T cells may get reactivated. On the basis of our data, TPP-1 peptide could work as an alternative to antibodies for tumor immunotherapy..

Interfering with MIF-CD74 signalling on macrophages and dendritic cells with a peptide-based approach restores the immune response against metastatic melanoma

“…However, in the field of drug discovery, peptide based approaches emerge with intrinsic advantages, compared to antibodies including their small size, lack of immunogenicity, high affinity, specificity to different targets, low toxicity, good tissue penetration and biocompatibility (22,25,26). Peptides can exert immunomodulatory functions and have been shown to neutralize immune checkpoint receptors in cancer (68)(69)(70). Indeed, linear peptides such as CDR peptides are flexible and likely to bind to different biologically relevant targets (41).…”

Undo the brake of tumour immune tolerance with antibodies, peptide mimetics and small molecule compounds targeting PD‐1/PD‐L1 checkpoint at different locations for acceleration of cytotoxic immunity to cancer cells

“…88 In addition by bacterial surface display methods for peptides that bind PD-L1, targeting PD-L1 peptide (TPP-1) was identified and verified to interfere with the interaction of PD-1/PD-L1 by a T-cell activation assay and mixed lymphocyte reaction. 89 In a xenograft mouse model using H460 cells, TPP-1 and PD-L1 antibody inhibits the tumour growth rates by 56% and 71%, respectively, with increased IFN-γ and granzyme B expression. 89 By characterizing two classes of macrocyclic peptide inhibitors directed at the PD-1/PD-L1 pathway, macrocyclic peptides were found to act by directly binding to PD-L1, capable of antagonizing PD-L1 signalling.…”

“…89 In a xenograft mouse model using H460 cells, TPP-1 and PD-L1 antibody inhibits the tumour growth rates by 56% and 71%, respectively, with increased IFN-γ and granzyme B expression. 89 By characterizing two classes of macrocyclic peptide inhibitors directed at the PD-1/PD-L1 pathway, macrocyclic peptides were found to act by directly binding to PD-L1, capable of antagonizing PD-L1 signalling. 90 Similarly to antibodies, the macrocyclic peptide inhibitors restore the function of T-cells with a rationale for the checkpoint inhibition by these relatively small molecules with the crystal structures showing the two inhibitors bound to PD-L1, demonstrating the interfaces peptidic binding to PD-L1 for further design of small-molecule inhibitors of the PD-1/PD-L1 pathway.…”

“…Using a computational de novo peptide design method for peptides potentially to bind PD‐1, the peptide Ar5Y_4 with a Kd value of 1.38 ± 0.39 μmol/L, which is comparable to the Kd value of the cognate PD‐L1, inhibits the binding of PD‐L1 to PD‐1 and restores the function of suppressed Jurkat T‐cells . In addition by bacterial surface display methods for peptides that bind PD‐L1, targeting PD‐L1 peptide (TPP‐1) was identified and verified to interfere with the interaction of PD‐1/PD‐L1 by a T‐cell activation assay and mixed lymphocyte reaction . In a xenograft mouse model using H460 cells, TPP‐1 and PD‐L1 antibody inhibits the tumour growth rates by 56% and 71%, respectively, with increased IFN‐γ and granzyme B expression …”

“…In addition by bacterial surface display methods for peptides that bind PD‐L1, targeting PD‐L1 peptide (TPP‐1) was identified and verified to interfere with the interaction of PD‐1/PD‐L1 by a T‐cell activation assay and mixed lymphocyte reaction . In a xenograft mouse model using H460 cells, TPP‐1 and PD‐L1 antibody inhibits the tumour growth rates by 56% and 71%, respectively, with increased IFN‐γ and granzyme B expression …”