FORCE platform overcomes barriers of oligonucleotide delivery to muscle and corrects myotonic dystrophy features in preclinical models.

Abstract

Background: We developed the FORCE^TM platform to overcome limitations of oligonucleotide delivery to muscle and enable their applicability to neuromuscular disorders. The platform consists of an antigen-binding fragment, highly specific for the human transferrin receptor 1 (TfR1), conjugated to an oligonucleotide via a cleavable valine-citrulline linker. Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder caused by expanded CUG triplets in the DMPK RNA, which sequester splicing proteins in the nucleus, lead to spliceopathy, and drive disease progression.

Methods: Multiple surrogate conjugates were generated to characterize the FORCE platform. DYNE-101 is the conjugate designed to target DMPK and correct spliceopathy for the treatment of DM1. HSA^LR and TfR1^hu/mu;DMSXL^Tg/Tg mice were used as models of myotonic dystrophy, the latter expresses human TfR1 and a human DMPK RNA with >1,000 CUG repeats. Cynomolgus monkeys were used to determine translatability of DYNE-101 pharmacology to higher species.

Results: In HSA^LR mice, a surrogate FORCE conjugate achieves durable correction of spliceopathy and improves myotonia to a greater extent than unconjugated ASO. In patient-derived myoblasts, DYNE-101 reduces DMPK RNA and nuclear foci, consequently improving spliceopathy. In TfR1^hu/mu;DMSXL^Tg/Tg mice, DYNE-101 reduces mutant DMPK RNA in muscle, thereby correcting splicing. Reduction of DMPK foci in cardiomyocyte nuclei accompanies these effects. Low monthly dosing of DYNE-101 in TfR1^hu/mu;DMSXL^WT/Tg mice or cynomolgus monkeys leads to a profound reduction of DMPK expression in muscle.

Conclusions: These data validate FORCE as a drug delivery platform and support the notion that DM1 may be treatable with low and infrequent dosing of DYNE-101.