"Broadening the Understanding of Peptide Conjugated Oligonucleotides Platform to Expand Therapeutic Use"

Understanding PMOs and the Role of EDOs

At PepGen, we work with unique types of oligonucleotides called phosphorodiamidate morpholino oligomers (PMOs) which, when unconjugated, are neutral molecules that struggle to penetrate cells. While their chemistry allows them to bind sterically and facilitate exon-skipping or splice correction of target transcripts, their cellular uptake is minimal.

That’s where our Enhanced Delivery Oligonucleotide (EDO) technology platform is crucial. EDOs are the result of combining PMOs with cell-penetrating peptides (CPPs), specially designed to improve cellular uptake. These CPPs are positively charged and have unique structural features that allow them to enter cells, delivering the PMOs where they’re needed most.

The Evolution of Cell-Penetrating Peptides (CPPs)

The concept of CPPs isn’t new—they were first inspired by viral peptides like TAT and Penetratin. Over time, scientists modified these peptides, creating earlier-generation CPPs, such as Pips, which incorporated a hydrophobic core and unnatural amino acids to boost cellular uptake and stability.

While these earlier CPPs succeeded in delivering their cargoes, they posed tolerability challenges that limited their therapeutic potential. At PepGen, we’ve gone a step further. Through rigorous empirical testing, we’ve engineered next-generation CPPs that we believe have the potential to strike the perfect balance between efficacy and tolerability. These advanced CPPs are relatively short strings of amino acids at less than 17 amino acids in length, and feature optimized hydrophobic cores, arginine-rich regions, and strategically placed unnatural amino acids. The result of PepGen’s hard work is peptides with enhanced drug-like properties that we believe are well-suited for clinical use.

Why Intracellular Delivery Matters

Precursor mRNA (pre-mRNA) is the primary transcript in the transcription process. It contains both exons (coding sequence) and introns (non-coding sequence). During processing, the intronic regions are spliced out to form mRNA, which is subsequently translated into functional proteins.

In diseases caused by genetic mutations, PMOs are designed to target and modify the resulting mRNA to enhance therapeutic benefit. The more efficiently we can deliver PMOs into cells—and specifically into the nucleus where the pre-mRNA targets are—the better they can do their job. PepGen’s next-generation CPPs play a pivotal role in ensuring high levels of oligonucleotides are delivered to the nucleus, where they can engage pre-mRNA targets and potentially drive therapeutic benefits.

Importance of Enhanced Endosomal Escape

Endolysosomal uptake and trafficking are key pathways for the internalization and movement of most drugs within cells. After endocytosis, drugs must escape the endosomal compartment to reach their targets in the cytoplasm or nucleus.

We have measured the endosomal escape of our EDOs.?Consistent with the higher cellular uptake of PepGen’s next-generation EDOs compared to previous CPPs, we observe increased endosomal escape of these materials as well. We believe this endosomal escape and penetration into the nucleus should lead to superior clinical efficacy compared to predecessor approaches.

What’s Next for the EDO Platform?

We believe our EDO platform has a great deal of potential. We are already evaluating safety and efficacy in clinical trials for Duchenne muscular dystrophy (DMD) and myotonic dystrophy type 1 (DM1). Beyond that, our preclinical research is exploring how EDOs can target additional organs and deliver new types of therapeutic cargoes in other diseases.

It’s an exciting time at PepGen as we believe our approach could pave the way to tackle a broader range of rare diseases with unmet medical need.