Delivery is key: lessons learnt from developing splice‐switching antisense therapies

Abstract

The use of splice‐switching antisense therapy is highly promising, with a wealth of pre‐clinical data and numerous clinical trials ongoing. Nevertheless, its potential to treat a variety of disorders has yet to be realized. The main obstacle impeding the clinical translation of this approach is the relatively poor delivery of antisense oligonucleotides to target tissues after systemic delivery. We are a group of researchers closely involved in the development of these therapies and would like to communicate our discussions concerning the validity of standard methodologies currently used in their pre‐clinical development, the gaps in current knowledge and the pertinent challenges facing the field. We therefore make recommendations in order to focus future research efforts and facilitate a wider application of therapeutic antisense oligonucleotides.

Short-hairpin RNA against aberrant HBBIVSI-110(G>A) mRNA restores β-globin levels in a novel cell model and acts as mono- and combination therapy for β-thalassemia in primary hematopoietic stem cells

“…Indeed, in cases of stable transcripts with aberrant exon boundaries, splice correction by non-permanent delivery of antisense oligonucleotides would normally be suggested. 16,17 However, the present study indicates that action by LV-encoded shRNAs and a resulting increase of normal protein production from the mutant locus should be investigated as a potentially superior therapeutic option. Our findings in MEL-HBB IVSI-110(G>A) and CD34 + cells are therefore not only important for our understanding of disease causation and therapy development for HBB IVSI-110(G>A) β-thalassemia, but also as an analysis and therapy approach for other diseases.…”

Efficacy and Safety Profile of Tricyclo-DNA Antisense Oligonucleotides in Duchenne Muscular Dystrophy Mouse Model

“…However, numerous specific and early biomarkers of toxicity can now be evaluated in mice (treated with high doses of AONs) to predict toxicity in pre-clinical development 20 . These delivery challenges were recognized by experts from the COST Action BM1207 “Networking towards clinical implementation of antisense-mediated exon skipping for rare diseases” 21 (http://exonskipping.eu), and it is becoming clear that these toxicological challenges should be addressed in the very early stages of new AON development to ensure the clinical translation of these studies 22 . Because tcDNA chemistry has never been used in the clinic, as opposed to other naked chemistries, which have been evaluated for other applications before DMD, we believe it is of importance to evaluate its toxicological profile in mice before undertaking expensive and lengthy reglementary toxicological studies.…”

Improvement of Duchenne muscular dystrophy phenotype following obestatin treatment

“…In this sense, obestatin‐mediated fibre restoration would allow the maintenance of vector or cell content in the decisive period between injection and transgene expression in the dystrophic muscles. For instance, the stability of the pre‐conditioned muscle fibre could help mitigate the loss of therapeutic vectors in gene therapy and guarantee a higher therapeutic benefit in restoration of dystrophin in the muscles of DMD patients . The results presented so far provide compelling evidence for a potential way of treating DMD.…”

“…Different potential therapeutic approaches are presently undergoing clinical evaluation . However, current strategies for the treatment of dystrophic skeletal muscle, whether these are gene or cell‐based, face the bottleneck that targeted fibres often degenerate before they are fully rescued, thus causing the loss of the therapeutic agent . A potential approach would be the use of autocrine/paracrine signals involved in muscle regeneration to enhance endogenous satellite cell function and temporarily protect the fibres from degenerating while gene or cell therapy is applied.…”