Cell-penetrating peptide-conjugated, splice-switching oligonucleotides mitigate the phenotype in BTK/Tec double deficient X-linked agammaglobulinemia model.
Bestas B., Estupiñán HY., Wang Q., Kharazi S., He C., K Mohammad D., Gupta D., Wiklander OPB., Lehto T., Lundin KE., Berglöf A., Karlsson MCI., Abendroth F., El Andaloussi S., Gait MJ., Wood MJA., Leumann CJ., Stetsenko DA., Månsson R., Wengel J., Zain R., Smith CIE.
Splice-switching oligonucleotides (SSOs) have been developed as a treatment for various disorders, including Duchenne muscular dystrophy and spinal muscular atrophy. Here, the activity of several different SSOs was investigated as potential treatments for B lymphocyte disorders with a focus on X-linked agammaglobulinemia (XLA), caused by defects in the gene encoding Bruton's tyrosine kinase (BTK). In this study, the activity of locked nucleic acid (LNA), tricyclo-DNA (tcDNA), phosphoryl guanidine oligonucleotides (PGO) and phosphorodiamidate morpholino oligomers (PMO) were compared, targeting the pseudoexon region of BTK pre-mRNA. We further investigated the effect of conjugating cell-penetrating peptides, including Pip6a, to the SSOs. The effect was measured as splice-switching in vitro as well as in a further developed, bacterial artificial chromosome transgenic mouse model of XLA. Therapy in the form of intravenous infusions 2 times a week during 3 weeks of PMO oligomers conjugated to Pip6a was sufficient to partly restore the in vivo B lineage phenotype. SSOs treatment also provides a unique opportunity to get insights into a restoration process, when B lymphocytes of different maturation stages are simultaneously splice-corrected.