A New Platform for Oligonucleotide Delivery Utilizing the PEG Prodrug Approach

Abstract

The oligonucleotide (oligo, ODN), Genasense (GS), an ODN currently waiting for FDA approval, was chosen as a model and modified with a 5' or 3' aminohexyl functionality (1 and 4, respectively) using solid-state synthesis. These amino derivatives were reacted with different releasable PEGs (rPEGs). The in vitro results of the PEG-modified oligos (Table 1) clearly show a substantial increase in rat plasma half-life and enhanced stability against a variety of nucleases, especially the predominant nuclease (PEII) in mammals, which is the main source of oligo degradation in cells. The advantage of using a PEG prodrug approach was further demonstrated by the pharmacokinetic (PK) results, which exhibited much greater C(max), plasma half-life, and area under the curve (AUC) for 3 compared to unmodified GS. A key step in the synthesis of ODN prodrug conjugates with a dye label was also accomplished successfully by employing dihydropyran derivatives of alcohols and acids as orthogonal protecting groups during the synthesis.

New Syntheses of Branched, Multifunctional High-Molecular Weight Poly(ethylene glycol)s or (MultiPEG)s

“…It must also be recalled that medium-size bioactive molecules, such as peptides and oligonucleotides, have been subject of such PEG conjugations to increase their solubilisation, cellular uptake, and in vivo stability toward degradation processes [11,12]. Additionally, the use of PEG-based systems as inert, soluble synthetic supports in organic synthesis has been extensively exploited and evaluated for convenient applications on environment compatible synthetic processes [13,14].…”

PEGylation of therapeutic oligonucletides: From linear to highly branched PEG architectures

“…PEGylation slightly improves t 1/2α , which is, however, still generally < 1 h. The majority of injected ONs are quickly removed from blood circulation despite their PEGylation status or whether phosphorothioates are used [90]. PEGylation is known to prolong elimination half-life ( t 1/2β ) to several hours [84, 91, 92].…”

Bioconjugation of Oligonucleotides for Treating Liver Fibrosis

“…Normally, a phosphate bond between PEG and ODN is formed. However, different chemistries in the linker between ODN and PEG can also been introduced (493)(494)(495), which may confer better properties to the conjugates. PEG can be introduced after the synthesis of ODNs, which contain reactive groups, such as amines or thiols.…”

“…For example, ODNs can be easily introduced with a 5' or 3' aminohexyl functionality. The formation of carbamate between ODN and PEG enables the release ability of ODN (494).…”