Hypersensitivity and Loss of Disease Site Targeting Caused by Antibody Responses to PEGylated Liposomes

Abstract

The systemic application of nucleic acid drugs requires delivery systems that overcome the poor pharmacokinetics, limited biodistribution, and inefficient uptake of nucleic acids. PEGylated liposomes show considerable promise because of their intrinsic ability to accumulate at disease sites and facilitate transfection of target cells. Unlike many viral vectors, PEGylated liposomes are generally considered to be nonimmunogenic. We have developed a PEGylated liposome for the systemic administration of plasmid DNA that achieves high levels of selective gene expression at distal tumor sites. Here we report that the in vivo efficacy and safety of these systems can be severely compromised following repeat administration. This phenomenon is characterized by a loss of disease site targeting, accelerated clearance from the blood, and acute hypersensitivity. These effects are fully attributable to a surprisingly robust, long-lived antibody response generated against polyethylene glycol (PEG) that results from the strong adjuvant effect of the plasmid payload. Importantly, immunogenicity may be substantially reduced by modifying the alkyl chain of the PEG-lipid conjugate, thereby allowing successful repeat dosing of the modified plasmid formulations without adverse side effects. Immunogenicity is a relevant concern for a number of nonviral delivery systems given the potent immunostimulatory properties of many nucleic acid drugs.

Immune responses of therapeutic lipid nanoparticles

“…The ABC phenomenon was also reported with other PEGylated lipid nanoparticles containing pDNA [49] . Judge and colleagues [49] reported that stable plasmid lipid particles (SPLPs) incorporating PEG-S-DSG (a PEGylated lipid containing a C18 alkyl chain) or PEG-S-DPG (C16) increased serum levels of anti-PEG IgM, which in turn reduced gene transfection activity in the tumor by ∼ 10-fold for the second injection.…”

“…Judge and colleagues [49] reported that stable plasmid lipid particles (SPLPs) incorporating PEG-S-DSG (a PEGylated lipid containing a C18 alkyl chain) or PEG-S-DPG (C16) increased serum levels of anti-PEG IgM, which in turn reduced gene transfection activity in the tumor by ∼ 10-fold for the second injection. However, when the acyl chain length of the PEGylated lipid was reduced to C14 (PEG-S-DMG), the resulting SPLPs only induced mild increases in serum levels of anti-PEG IgM (only 1/3 or less compared to the C16 and C18 SPLPs).…”

Developing Lipid Nanoparticle-Based siRNA Therapeutics for Hepatocellular Carcinoma Using an Integrated Approach

“…PEG-lipids with longer acyl chain confer stronger interaction with membrane lipids thus less likely to be extracted/exchanged, and consequently, PEGs with longer lipid anchor are often associated with a slower rate of deshielding (15,(19)(20)(21). Our results suggest that PEG-DMPE may be shed rapidly to expose the "naked" lipid particle consisting of fusogenic lipid D-Lin-DMA, which allows it to fuse with the cell membrane to achieve efficient siRNA transfection in vitro.…”

“…It consists of cholesterol, DSPC, D-Lin-DMA and PEG-C-DMA. Among these components, the neutral lipids DSPC and cholesterol are commonly used in many liposome formulations for maintaining liposome structure whereas PEG-C-DMA and DLin-DMA are unique components of SNALP that are critical for its in vivo delivery efficiency (14,15).…”

Administration in non-human primates of escalating intravenous doses of targeted nanoparticles containing ribonucleotide reductase subunit M2 siRNA

“…Also, it is important to note that no adverse reactions were observed in the animals from the final 3-mg/kg dose when antibodies were present. This result contrasts with the adverse reactions observed with repeated administration of lipid-based systems that are associated with the presence of antibodies (22,23,(25)(26)(27)(28).…”