PD-L1 DNA aptamers isolated from agarose-bead SELEX

Area of Science:

• Biochemistry
• Molecular Biology
• Immunology

Background:

• The PD-L1/PD-1 pathway is crucial in anti-tumour immunity, and its dysregulation promotes tumor growth.
• Antibody-based therapies targeting PD-1/PD-L1 are effective cancer treatments but have limitations.
• Aptamers represent a novel class of molecules with potential as alternatives to antibodies.

Purpose of the Study:

• To isolate and characterize DNA aptamers specific to recombinant human PD-L1 (rhPD-L1).
• To evaluate the binding affinity, specificity, and competitive inhibition of selected aptamers against PD-L1.

Main Methods:

• Systematic Evolution of Ligands by Exponential Enrichment (SELEX) was used to isolate DNA aptamers.
• Aptamer sequences were analyzed using MEGA X, and structural features were examined with mFold.
• Binding affinity (K_d) was assessed using ELONA, and specificity/inhibition was evaluated electrochemically.

Main Results:

• Three aptamer candidates (P33, P32, P12) were identified.
• Aptamer P32 demonstrated high specificity for PD-L1 with a dissociation constant (K_d) of 8 nM.
• P32 competes with the control antibody 28-8 for the same binding site on PD-L1.

Conclusions:

• DNA aptamer P32 exhibits high specificity for PD-L1.
• P32 warrants further investigation as a potential cost-effective alternative to antibodies for targeting PD-L1 in cancer therapy.