Development and characterization of single domain monoclonal antibody against programmed cell death ligand-1; as a cancer inhibitor candidate

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Programmed cell death-1 (PD-1) and its ligand (PD-L1) are key negative regulators of the immune system.
• Tumor cells exploit PD-L1 expression for immune evasion, down-regulating anti-tumor responses.
• Checkpoint inhibitors (CPIs) are emerging anti-cancer agents that block PD-1/PD-L1 interactions to restore immune function.

Purpose of the Study:

• To develop and characterize a novel nanobody (Nb) targeting human PD-L1 as a potential CPI.
• To evaluate the binding affinity, specificity, and functional activity of the anti-PD-L1 Nb.

Main Methods:

• Immunization of a camel with recombinant PD-L1 protein to generate a nanobody library.
• Selection and characterization of PD-L1 specific nanobodies using ELISA, Western blotting, and flow cytometry.
• Assessment of the nanobody's inhibitory effect and cytotoxicity on cancer cells (A431, HEK293) via MTT assay.

Main Results:

• A specific nanobody, designated A22, was developed with high affinity and specificity for human PD-L1.
• Nanobody A22 effectively detected and bound to PD-L1 on cell surfaces and in lysates.
• The anti-PD-L1 nanobody inhibited PD-L1 function in cancer cells without causing observable cytotoxicity.

Conclusions:

• The developed anti-PD-L1 nanobody (A22) shows significant potential as a novel therapeutic agent for cancer treatment.
• This nanobody offers a promising approach for cancer immunotherapy due to its efficacy and lack of cytotoxicity.