PepGen Inc. (NASDAQ:PEPG), a clinical-stage biotechnology company advancing the next generation of oligonucleotide therapies with the goal of transforming the treatment of severe neuromuscular and neurological diseases, today announced that data from its PGN-EDODM1 program will be presented in a poster and late-breaking oral presentation at the 15th International Myotonic Dystrophy Consortium (IDMC-15) being held May 26-30, 2026, in Saguenay, Quebec, Canada. The late-breaking oral presentation will include analyses of individual patient mis-splicing data from the PGN-EDODM1 program, as well as natural history data characterizing mis-splicing in patients with myotonic dystrophy type 1 (DM1).

Ahead of IDMC-15, PepGen's President and Chief Executive Officer, James McArthur, PhD, will present single and initial multiple ascending dose data for PGN-EDODM1 at the 6th Annual Pharma Day, co-hosted by Euro-DyMA and the Myotonic Dystrophy Foundation (MDF), on May 26, 2026, at 11:00–11:20am EDT in Saguenay, Quebec, Canada.

IDMC-15 Presentation Details:

Title: Analysis of Individual Patient Mis-Splicing Data from PGN-EDODM1, an Investigational Therapy for Myotonic Dystrophy Type 1 (DM1)

Presentation Type: Late-Breaking Oral Presentation

Session: Late-Breaking Industry Session

Date & Time: Thursday, May 28^that 3:15–4:15pm EDT

Presenter: James McArthur, PhD, President and Chief Executive Officer of PepGen

Title: The FREEDOM-DM1 clinical trial demonstrated strong splicing correction with single doses of PGN-EDODM1, with an acceptable safety profile

Presentation Type: Poster Session

Date & Time: Wednesday, May 27^th at 10:45am–12:15pm EDT and Thursday, May 28^th at 4:15–7:00pm EDT

Presenter: Dr. Johanna Hamel, Associate Professor of Neurology, Pathology and Laboratory Medicine at the University of Rochester Medical Center

Following the conference, the presentations presented at IDMC-15 will be available on PepGen's website under Scientific Publications.

About PGN-EDODM1

PGN-EDODM1, PepGen's investigational candidate in development for the treatment of DM1, utilizes the Company's proprietary EDO technology to deliver a therapeutic oligonucleotide that is designed to restore the normal splicing function of MBNL1, a key RNA splicing protein. PGN-EDODM1 addresses the deleterious effects of cytosine-uracil-guanine (CUG) repeat expansion in the dystrophia myotonica protein kinase (DMPK) transcripts which sequester MBNL1, by binding to the pathogenic CUG trinucleotide repeat expansion present in the DMPK transcripts and disrupting the binding between the CUG repeat expansion and MBNL1. PepGen believes this innovative therapeutic approach may have considerable advantages over oligonucleotide modalities that rely on knockdown or degradation of the DMPK transcripts as it will allow the DMPK transcripts to continue to perform their normal function within the cell, while also liberating MBNL1 to correct downstream mis-splicing events. The U.S. Food and Drug Administration has granted PGN-EDODM1 both Orphan Drug and Fast Track Designations for the treatment of patients with DM1. The European Medicines Agency (EMA) has granted Orphan Designation for PGN-EDODM1.

About Myotonic Dystrophy Type 1 (DM1)

Myotonic dystrophy type 1 (DM1) is a rare, progressive, and highly variable genetic neuromuscular disease caused by an abnormal expansion of cytosine-thymine-guanine (CTG) repeats in the dystrophia myotonica protein kinase (DMPK) gene. DM1 affects over 115,000 individuals in the U.S. and EU and is characterized by widespread, multisystem symptoms that may include myotonia, progressive muscle weakness, fatigue, cardiac abnormalities, respiratory impairment, and cognitive dysfunction. The disease is driven by toxic RNA transcripts containing expanded cytosine-uracil-guanine (CUG) repeats that sequester muscle blind-like 1 (MBNL1), a key RNA splicing protein, leading to widespread mis-splicing across multiple tissues. There are currently no approved disease-modifying therapies for DM1, underscoring the significant unmet medical need for patients living with the disease.

About PepGen

PepGen Inc. is a clinical-stage biotechnology company developing the next generation of oligonucleotide therapies with the goal of transforming the treatment of severe neuromuscular and neurological diseases. PepGen's Enhanced Delivery Oligonucleotide (EDO) platform is founded on over a decade of research and development and leverages cell-penetrating peptides to improve the uptake and activity of conjugated oligonucleotide therapeutics. Using these EDO peptides, the Company is generating a pipeline of oligonucleotide therapeutic candidates designed to target the root cause of serious diseases.

For more information, please visit PepGen.com. Follow PepGen on LinkedIn and X.

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PepGen Announces Presentations at the 15th International Myotonic Dystrophy Consortium Highlighting Clinical Data from the PGN-EDODM1 Program