Three Novel Enhanced Delivery Oligonucleotide Candidates for Duchenne Muscular Dystrophy (DMD) Mediated High Levels of Exon 53, 45, and 44 Skipping


Pre-Clinical Research

Poster Number: S18


Ashling Holland, PhD, PepGen, Hui Zhang, PhD, PepGen Inc, Colleen Sweeney, BS, PepGen Inc, James Gilbert, PhD, PepGen Inc, Pallavi Lonkar, Ph.D., PepGen Inc., Niels Svenstrup, PhD, PepGen Inc, Christopher Gibbons, PhD, PepGen Inc, Jaya Goyal, Ph.D., PepGen Inc.

Background: PepGen’s enhanced delivery oligonucleotide (EDO) cell-penetrating peptide technology is engineered to optimize tissue delivery and cellular uptake of therapeutic oligonucleotides. EDO candidates are being evaluated for potential treatment of DMD subpopulations amenable to exon 53, 45, or 44 skipping.

Objectives: In vitro and in vivo pharmacology studies to support development of PGN-EDO53, PGN-EDO45, and PGN-EDO44.

Design/Methods: Pharmacology profiles were characterized using normal human myotubes and DMD patient-derived myotubes (PGN-EDO53, PGN-EDO45, PGN-EDO44), and monkeys (PGN-EDO53, PGN-EDO45). In addition, pharmacology was characterized using the mdx model of DMD (using murine analogue PGN-EDO23 applicable to all DMD programs).

Results: Normal human myotubes were dosed with unconjugated PMO (phosphorodiamidate morpholino oligonucleotide) or EDOs (PGN-EDO53, PGN-EDO45, or PGN-EDO44). EDOs demonstrated greater DMD exon skipping activity versus unconjugated PMO with 12-, 34-, and 7-fold higher exon 53, 45, or 44 skipped transcripts, respectively. DMD patient-derived cells further confirmed pharmacological activity.

Single intravenous (IV) dose of 30 or 60 mg/kg PGN-EDO23 in mdx mice resulted in dose-dependent high levels of exon skipping and dystrophin production in biceps. Four monthly 30 mg/kg doses in mdx mice resulted in significant increase in exon skipping levels (91.5%) and dystrophin production (82.3%) suggesting potential accumulation of dystrophin with repeat dosing. Immunofluorescence evaluation showed dystrophin was uniformly distributed across muscle and resulted in 97.1% dystrophin positive area following repeat dosing.

One week following a single IV dose of PGN-EDO53 in monkey biceps, the mean exon 53 skipping level was almost 7-fold higher than for R6G-PMO53 comparator (36.4% versus 5%). Repeat-dose data in monkeys with PGN-EDO45, a novel exon 45 skipping molecule, will also be reported.

Conclusions: Combined, the nonclinical data support further development of PGN-EDO53, PGN-EDO45, PGN-EDO44. These EDOs, along with PGN-EDO51 (another DMD candidate), have the potential, if successful, to address 35% of the DMD population amenable to exon skipping.