A Glu-urea-Lys Ligand-conjugated Lipid Nanoparticle/siRNA System Inhibits Androgen Receptor Expression In Vivo

Abstract

The androgen receptor plays a critical role in the progression of prostate cancer. Here, we describe targeting the prostate-specific membrane antigen using a lipid nanoparticle formulation containing small interfering RNA designed to silence expression of the messenger RNA encoding the androgen receptor. Specifically, a Glu-urea-Lys PSMA-targeting ligand was incorporated into the lipid nanoparticle system formulated with a long alkyl chain polyethylene glycol-lipid to enhance accumulation at tumor sites and facilitate intracellular uptake into tumor cells following systemic administration. Through these features, and by using a structurally refined cationic lipid and an optimized small interfering RNA payload, a lipid nanoparticle system with improved potency and significant therapeutic potential against prostate cancer and potentially other solid tumors was developed. Decreases in serum prostate-specific antigen, tumor cellular proliferation, and androgen receptor levels were observed in a mouse xenograft model following intravenous injection. These results support the potential clinical utility of a prostate-specific membrane antigen–targeted lipid nanoparticle system to silence the androgen receptor in advanced prostate cancer.

State‐of‐the‐Art Design and Rapid‐Mixing Production Techniques of Lipid Nanoparticles for Nucleic Acid Delivery

“…The opposite was observed for particles designed for tumor accumulation. Increasing the amount of PEG‐C18 from 2.5 to 5.0 mol% resulted in elongated circulation times and an increased accumulation in tumor tissue . This highlights how, by altering the PEG anchor and density, LNP pharmacokinetics and tissue distribution may be tuned for specific applications.…”

“…For LNPs containing PEG‐C16 and C18, maximally 35% and 25%, respectively, accumulated in the liver and these maxima were reached at a later time point compared to PEG‐C14. Not surprisingly, for extra hepatic targets such as tumors, longer circulating LNPs using PEG‐C18 are used to improve tissue accumulation …”

Lipid nanoparticle technology for therapeutic gene regulation in the liver

“…Although there is preclinical evidence that LNP-siRNA can induce hepatic gene silencing following subcutaneous administration, the dose needed for effective gene silencing is considerably higher than for intravenously administered formulations [147]. Of note, while LNP-siRNA systems have been optimized for hepatic gene silencing, preclinical studies have also demonstrated their ability to induce effective gene silencing in extrahepatic target sites including the bone [244] and tumors [245,246]. A major area of interest is applying LNP-siRNA for immunotherapy, by silencing target genes in lymphocytes following intravenous administration for immunotherapy [247][248][249][250][251] (covered by Peer et al in this issue [252]).…”

Lipid Nanoparticles Enabling Gene Therapies: From Concepts to Clinical Utility

“…LNP-siRNA systems containing PEG-DSG (3-5 mol%; 30 nm diameter) that exhibit long circulation lifetimes (t 1/2 of 10-12 h) have been used to knock down the androgen receptor (AR), a fundamental driver of prostate cancer, in an LNCaP xenograft model [68]. However, the dose of LNP-siRNA required to achieve appreciable gene silencing was 30 mg/kg, more than 6,000 times higher than required to achieve an ED 50 in hepatocytes.…”

“…However, the dose of LNP-siRNA required to achieve appreciable gene silencing was 30 mg/kg, more than 6,000 times higher than required to achieve an ED 50 in hepatocytes. In an effort to improve potency, a targeting ligand for the prostate-specific membrane antigen was incorporated, resulting in improved gene silencing activity [68], but not the orders of magnitude improvement required for clinical potential. Similarly, knockdown activity and tumor growth delay were reported at distal tumors in an enzalutamide-resistant LNCaP xenograft model when LNP-siRNA against clusterin was used in combination with AR-ASO [69].…”