Systemic antisense therapeutics inhibiting DUX4 expression ameliorates FSHD-like pathology in an FSHD mouse model

Abstract

Aberrant expression of the double homeobox 4 (DUX4) gene in skeletal muscle causes muscle deterioration and weakness in Facioscapulohumeral Muscular Dystrophy (FSHD). Since the presence of a permissive pLAM1 polyadenylation signal is essential for stabilization of DUX4 mRNA and translation of DUX4 protein, disrupting the function of this structure can prevent expression of DUX4. We and others have shown promising results using antisense approaches to reduce DUX4 expression in vitro and in vivo following local intramuscular administration. Here we demonstrate that further development of the antisense chemistries enhances in vitro antisense efficacy. The optimal chemistry was conjugated to a cell-penetrating moiety and was systemically administered into the tamoxifen-inducible Cre-driver FLExDUX4 double-transgenic mouse model of FSHD. After four weekly treatments, mRNA quantities of DUX4 and target genes were reduced by 50% that led to 12% amelioration in muscle atrophy, 52% improvement in in situ muscle strength, 17% reduction in muscle fibrosis, and prevention of shift in the myofiber type profile. Systemic DUX4 inhibition also significantly improved the locomotor activity and reduced the fatigue level by 22%. Our data demonstrate that the optimized antisense approach has potential of being further developed as a therapeutic strategy for FSHD.

Systemic delivery of a DUX4-targeting antisense oligonucleotide to treat facioscapulohumeral muscular dystrophy

“… 29 , 30 , 31 For FSHD, no ASOs have yet been tested in patients; different studies, however, have shown that ASOs were efficient in reducing DUX4 and DUX4 target genes in FSHD myocytes and in FSHD mice. 15 , 16 , 17 , 18 , 19 , 21 A major advantage of our systemic approach compared to most other in vivo studies in FSHD mice is that all tested skeletal muscles were targeted by the ASO instead of one muscle or a part of the muscle. Next, this is the first ASO with cEt chemistry that has been tested for FSHD.…”

“…The ASO was able to reduce the DUX4 mRNA transcript, DUX4 target gene expression, and pathology in the tibialis anterior muscle. 21 …”

Downstream events initiated by expression of FSHD-associated DUX4: Studies of nucleocytoplasmic transport, γH2AX accumulation, and Bax/Bak-dependence

“…As potential therapies for FSHD, multiple groups are developing technologies to inhibit the function or expression of DUX4-FL (e.g. Bosnakovski et al, 2019 ; Bouwman et al, 2021 ; Das and Chadwick, 2021 ; Himeda et al, 2020 ; Lim et al, 2020 , 2021 ; Lu-Nguyen et al, 2021 ; Mariot et al, 2020 ; Mellion et al, 2021 ; Oliva et al, 2019 ; Rashnonejad et al, 2020 ; Šikrová et al, 2021 ). Direct targeting of DUX4 will likely be the primary therapeutic strategy for FSHD, because once begun, any technique that inhibits DUX4 expression or function should block multiple pathogenic changes that are dependent on DUX4 transcriptional activity ( Mitsuhashi et al, 2018 ).…”

Meeting report: the 2021 FSHD International Research Congress

“…This treatment led to partial reductions in DUX4 and 2 DUX4-activated mouse target genes and partial improvement in histological and functional outcomes. This study is now published [ 19 ].…”