Dose-Dependent Pharmacokinetic Profiles of 2′-O-Methyl Phosphorothioate Antisense OligonucleotidesinmdxMice

Abstract

Antisense-mediated exon skipping is a promising therapeutic approach for Duchenne muscular dystrophy. It aims to restore the dystrophin open reading frame by skipping exons with antisense oligonucleotides (AONs) to allow production of partly functional proteins. The approach is currently tested in phase 3 clinical trials, but dosing and maintenance regimens have not yet been well studied. This study compared pharmacokinetic and pharmacodynamic effects of different 2'-O-methyl phosphorothioate RNA AON dosing and maintenance regimens in the preclinical mdx mouse model. When comparing different dosing regimens over a period of 8 weeks, higher levels of AON, exon skipping, and protein were observed in muscle after low daily doses compared with large weekly doses. Secondly, after receiving a high loading dose (1,250 mg/kg) in the first week, mice treated with maintenance injections twice weekly for 8 weeks showed higher preservation of therapeutic effects than mice receiving less or no maintenance injections. In both cases, the regimen resulting in the highest AON and exon skipping levels in muscle also resulted in high AON levels in liver and kidneys. These studies underline the importance of balancing optimal AON efficacy and tolerable levels in non-target organs, which may be fine-tuned by further optimization of AON treatment regimens.

Splice-switching antisense oligonucleotides as therapeutic drugs

“…Finally, the DMD trials involve subcutaneous or intravenous administration to target skeletal muscles, whereas the SMA therapeutic is administered by intrathecal injection to specifically target the CNS. The pharmacokinetic profiles of ASOs in the CNS and peripheral organs are distinct, which likely affects the efficacy of an ASO (32,35,143). The fact that clinical trials with SSOs for DMD resulted in statistically significant changes in primary outcome measures suggest that the SSO may cause some exon skipping, but the lack of convincing clinical benefit to patients suggests that more work must be done to improve SSO efficacy by optimizing delivery, dosing or other features of the treatment and or SSO.…”

Functional correction in mouse models of muscular dystrophy using exon-skipping tricyclo-DNA oligomers

“…This discrepancy could be due either to more stringent quantification methods or to a suboptimal dosing regimen of PMO or 2′OMe, which are more potent following administration of multiple low doses [29][30][31] . A similar effect could also occur for tcDNA, especially considering its long lasting activity, and regimens designed to balance the possibility of toxicity due to chronic exposure to high levels of AONs may lead to disease-ameliorating levels of dystrophin.…”

Intracellular Distribution and Nuclear Activity of Antisense Oligonucleotides After Unassisted Uptake in Myoblasts and Differentiated MyotubesIn Vitro

“…To examine the potential effects on gymnosis by the nucleotide composition of the AON, we also followed the fate of Cy3-DMD23-OMePS, an AON that induces exon 23 skipping during splicing of mouse Dmd pre-mRNA [27]. When used under the same experimental conditions, a similar localization was observed with this AON (Fig.…”

“…Two classes of AONs were compared: (1) analogs of a CAG7 AON for degradation of expanded DMPK (CUG)n transcripts for DM1 [7,15] and (2) variants of DMD23, an AON capable of inducing exon 23 skipping in mouse Dmd transcripts [27] (Table 1). We followed uptake and intracellular distribution of these AONs during gymnosis by means of fluorescence microscopy during myoblast proliferation and differentiation.…”