Related Experiment Video
Updated: Feb 20, 2026
Development of a 68Gallium-Labeled D-Peptide PET Tracer for Imaging Programmed Death-Ligand 1 Expression
Published on: February 3, 2023
Identification and Validation of a PD-L1 Binding Peptide for Determination of PDL1 Expression in Tumors
Charles Caldwell1,2, Cory E Johnson3, V N Balaji4
1Departments of Radiology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA.
Abstract:
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.
Insights
A novel peptide, RK-10, offers improved detection of Programmed Death Ligand 1 (PD-L1) in tumors compared to current methods. This peptide enhances immunotherapy by enabling more accurate identification of PD-L1 expressing cancers for treatment.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Blocking Programmed Death Ligand 1 (PD-L1) and its receptor PD-1 interaction is a key cancer immunotherapy strategy.
- Tumor overexpression of PD-L1 can suppress anti-tumor immune responses.
- Current PD-L1 diagnostic methods exhibit variability, impacting treatment efficacy.
Purpose of the Study:
- To develop and evaluate a novel peptide, RK-10, for more precise PD-L1 detection in tumors.
- To compare the efficacy of RK-10 with existing diagnostic methods, including FDA-approved kits.
Main Methods:
- RK-10 was modified with fluorescent (RK-10-Cy5) and biotin (RK-10-Biotin) tags for detection.
- Flow cytometry was used to detect PD-L1 on cell lines and patient tissues with RK-10-Cy5.
- Immunohistochemistry (IHC) with RK-10-Biotin was performed on over 200 patient tissues (NSCLC, Hodgkin's Lymphoma) and compared to the SP263 clone.
Main Results:
- RK-10 demonstrated specific PD-L1 staining in tumor regions of FFPE tissues, including areas missed by the SP263 kit.
- RK-10-Cy5 successfully detected PD-L1 in various cancer types, including NSCLC, breast, squamous cell carcinoma, and melanoma.
- RK-10 shows potential for improved diagnostic accuracy in identifying PD-L1 expressing tumors.
Conclusions:
- The novel peptide RK-10 provides a promising alternative for accurate PD-L1 detection.
- RK-10's ability to identify PD-L1 in diverse tumor types and FFPE tissues enhances its diagnostic utility.
- Improved PD-L1 detection using RK-10 can potentially optimize cancer immunotherapy strategies.
More Related Videos
07:43Using 22C3 Anti-PD-L1 Antibody Concentrate on Biopsy and Cytology Samples from Non-small Cell Lung Cancer Patients
Published on: September 25, 2018
10:18Author Spotlight: Magnetic Fluorescent Bead-Based Dual-Reporter Flow Analysis of PDL1-Vaxx Peptide Vaccine-Induced Antibody Blockade of the PD-1/PD-L1 Interaction
Published on: July 7, 2023