Identification and Validation of a PD-L1 Binding Peptide for Determination of PDL1 Expression in Tumors

• Published in: Scientific reports Vol. 7; no. 1; pp. 13682 - 11
• Main Authors: Caldwell, Jr, Charles, Johnson, Cory E, Balaji, V N, Balaji, Govardhan A, Hammer, Richard D, Kannan, Raghuraman
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 20.10.2017; Nature Publishing Group UK
• Subjects: Apoptosis; B7-H1 Antigen - metabolism; Biomarkers, Tumor - metabolism; Biotin; Cell Line, Tumor; Flow cytometry; Humans; Immunohistochemistry; Immunosuppressive agents; Lung cancer; Lymphoma; Melanoma; Neoplasms - metabolism; Neoplasms - pathology; Non-small cell lung carcinoma; Patients; PD-1 protein; PD-L1 protein; Peptides; Peptides, Cyclic - metabolism; Protein Binding; Protein Conformation; Sensitivity and Specificity; Squamous cell carcinoma; Tumors
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-10946-2

Blocking the interaction between Programmed Death Ligand 1 (PD-L1) and its receptor, PD-1, is an effective method of treating many types of cancers. Certain tumors overexpress PD-L1, causing host immune cells that express PD-1 to bind PD-L1 and cease killing the tumor. Inhibition of PD-L1 and PD-1 binding can restore host immunity towards tumor killing, and many new drugs have been developed to target this interaction. Current methods of PD-L1 diagnosis have shown to vary based on the antibody, detection kit brand, antigen retrieval method, and clinically defined methods by the FDA. To refine detection of PD-L1, we have identified a peptide, RK-10, and used it to detect PD-L1 expressing tumors with immunohistochemistry or flow cytometry. Flow cytometry was performed on cell lines and patient tissues using a fluorescent peptide (RK-10-Cy5). Immunohistochemistry using a biotin-modified peptide (RK-10-Biotin) was tested against the FDA-approved SP263 clone on biopsied patient tissues. For this study, we evaluated specificity of RK-10 using IHC in over 200 patient tissues, including NSCLC and Hodgkin's Lymphoma. RK-10 shows staining in the tumor regions of FFPE tissues where the SP263 kit does not. RK-10-Cy5 peptide also demonstrates PD-L1 detection in NSCLC, breast, squamous cell carcinoma, and melanoma.