Novel Complex of PD-L1 Aptamer and Holliday Junction Enhances Antitumor Efficacy in Vivo

Abstract

Blocking the PD-1/PD-L1 pathway can diminish immunosuppression and enhance anticancer immunity. PD-1/PD-L1 blockade can be realized by aptamers, which have good biocompatibility and can be synthesized in quantity economically. For in vivo applications, aptamers need to evade renal clearance and nuclease digestion. Here we investigated whether DNA nanostructures could be used to enhance the function of PD-L1 aptamers. Four PD-L1 aptamers (Apt) were built into a Holliday Junction (HJ) to form a tetravalent DNA nanostructure (Apt-HJ). The average size of Apt-HJ was 13.22 nm, which was above the threshold for renal clearance. Apt-HJ also underwent partial phosphorothioate modification and had improved nuclease resistance. Compared with the monovalent PD-L1 aptamer, the tetravalent Apt-HJ had stronger affinity to CT26 colon cancer cells. Moreover, Apt-HJ markedly boosted the antitumor efficacy in vivo vs. free PD-L1 aptamers without raising systemic toxicity. The results indicate that multiple aptamers attached to a DNA nanostructure may significantly improve the function of PD-L1 aptamers in vivo.

Future Perspectives of Therapeutic, Diagnostic and Prognostic Aptamers in Eye Pathological Angiogenesis

“…Recently, researchers have conjugated an aptamer with HJ (Apt-HJ) that blocks the PD-1/PD-L1 pathway. Interestingly, Apt-HJ had stronger affinity to colon cancer cells compared to the monovalent PD-L1 aptamer [144].…”

“…PD-1 is its receptor expressed on activated T cells, and the interaction with its ligand PD-L1 inhibits T cell response. PD-L1 is expressed on numerous cells, including epithelial cells, endothelial cells and immune system cells [144]. Importantly, PD-L1 is commonly upregulated on the surface of tumor cells, and this confers a tumor evasion mechanism to avoid apoptosis from lymphocytes.…”

Nanopore Analysis as a Tool for Studying Rapid Holliday Junction Dynamics and Analyte Binding

“…Therefore, HJ modifications represent a highly promising therapeutic target. 9,54,55 With this potential application in mind, we also demonstrated target binding kinetics with specific targets. Both examples demonstrated that the observed fluctuations most likely result from the inherent HJ conformational fluctuations.…”

Novel Bispecific Aptamer Targeting PD-1 and Nucleolin for Cancer Immunotherapy

“…3). It has been demonstrated that the size of a nanostructure in uences the rate at which it will be cleared from the body via renal ltration (Li et al 2021). For fair comparison of the in vivo functions of PD-1 aptamer vs. BiApt, the PD-1 aptamer was attached to a DNA structure to form PD1-polyA, which had a similar molecular weight as BiApt.…”