8-K: PepGen Updates DM1 Drug Data, Eyes Phase 2 Milestones

PepGen Inc. updated its corporate presentation, highlighting positive Phase 1 data for PGN-EDODM1 in Myotonic Dystrophy Type 1 with unprecedented splicing correction and outlining upcoming Phase 2 milestones.

Summary

• PepGen Inc. updated its Corporate Presentation on October 1, 2025, detailing progress on its lead therapeutic candidate.
• PGN-EDODM1, designed for Myotonic Dystrophy Type 1 (DM1), demonstrates best-in-class potential by selectively targeting pathogenic DMPK RNA.
• The therapy has received Orphan Drug and Fast Track Designation in the U.S., and Orphan Drug Designation in the EU.
• The FREEDOM Phase 1 study (single-ascending dose) showed a mean splicing correction of 53.7% at 15 mg/kg, 29.1% at 10 mg/kg, and 12.3% at 5 mg/kg.
• All patients (100%) in the 15 mg/kg cohort responded to PGN-EDODM1 treatment.
• PGN-EDODM1 exhibited a favorable emerging safety profile and was generally well-tolerated across all doses tested.
• The FREEDOM2 Phase 2 study (multiple-ascending dose) is currently underway, with the 5 mg/kg cohort actively being dosed.
• Upcoming milestones include the release of FREEDOM2 5 mg/kg clinical results in Q1 2026 and 10 mg/kg results in H2 2026.
• The company projects its cash runway to extend into the second half of 2027.

Sentiment

Score: 8

Explanation: The filing presents strong preclinical and Phase 1 clinical data for PGN-EDODM1, particularly the unprecedented splicing correction and favorable safety profile. The clear path to Phase 2 and projected cash runway into 2H 2027 provide a positive outlook, despite the expected lack of functional improvement after a single dose.

Positives

• Achieved unprecedented mean splicing correction of 53.7% at the 15 mg/kg dose in the FREEDOM Phase 1 study, which is the highest ever reported in DM1 patients.
• 100% of patients in the 15 mg/kg cohort responded to PGN-EDODM1 treatment, indicating consistent and robust biological activity.
• PGN-EDODM1 demonstrated a favorable emerging safety profile and was generally well-tolerated across all doses, with all drug-related adverse events at 15 mg/kg being mild or moderate and resolving without intervention.
• Observed robust, greater than dose-proportional increases in muscle tissue concentration following a single dose, suggesting effective delivery of the therapeutic.
• Secured Orphan Drug and Fast Track Designation (U.S.) and Orphan Drug Designation (EU) for PGN-EDODM1, highlighting its potential to address an unmet medical need.
• The company's cash runway is projected into the second half of 2027, providing financial stability for ongoing development activities.
• The EDO platform has been designed to achieve superior nuclear delivery and uptake of therapeutic oligonucleotides, overcoming key limitations of prior approaches.

Negatives

• No significant functional improvements (e.g., 10-Meter Walk Run Test, video hand opening time) were observed after a single dose in the FREEDOM Phase 1 study, though the expectation is that more doses over a longer period are needed for functional benefit.
• One subject at 10 mg/kg in the FREEDOM Phase 1 study did not have a biopsy collected at Day 28 due to a pseudoaneurysm in connection with the biopsy.
• One subject at 15 mg/kg in the FREEDOM Phase 1 study received only 77% of the full dose.

Risks

• Delays or failure to successfully initiate or complete ongoing and planned development activities for product candidates, including PGN-EDODM1.
• Inability to enroll patients in clinical trials, including the FREEDOM2 study.
• Interpretation of clinical and preclinical study results may be incorrect, or anticipated levels of therapeutic activity may not be observed in clinical testing, including for PGN-EDODM1.
• Product candidates, including PGN-EDODM1, may not be safe and effective or otherwise demonstrate safety and efficacy in clinical trials.
• Adverse outcomes from regulatory interactions, including delays in regulatory review, clearance to proceed, or approval by regulatory authorities.
• Changes in the regulatory framework that are beyond the company's control.
• Inability to obtain, maintain, and protect intellectual property, or to enforce patents against infringers and defend the patent portfolio against challenges from third parties.
• Competition from other companies developing therapies for the indications being pursued.
• Unexpected increases in expenses associated with development activities or other events that adversely impact financial resources and cash runway.
• Dependence on third parties for some or all aspects of product manufacturing, research, and preclinical and clinical testing.

Future Outlook

PepGen anticipates the potential for significant correction of mis-splicing with more doses of PGN-EDODM1 over a longer treatment period to potentially provide improved functional benefit for patients with DM1. The company expects to report FREEDOM2 5 mg/kg clinical results in Q1 2026 and 10 mg/kg clinical results in H2 2026, with a cash runway extending into the second half of 2027.

Management Comments

• Our vision is to develop therapies that address the root cause of serious genetic neuromuscular and neurological diseases, driving meaningful, functional improvement.
• We aim to leverage our EDO platform to drive meaningful impact for patients, achieving superior nuclear delivery and uptake of therapeutic oligonucleotides, overcoming key limitations of prior approaches.
• We expect the potential for significant correction of mis-splicing with more doses of PGN-EDODM1 over a longer treatment period to potentially provide improved functional benefit for patients with DM1.

Industry Context

The development of PGN-EDODM1 by PepGen addresses a significant unmet medical need in Myotonic Dystrophy Type 1 (DM1), a rare genetic neuromuscular disease affecting over 115,000 patients in the U.S. and EU, with no approved therapies that target the underlying cause. PepGen's EDO platform aims to overcome key limitations of prior oligonucleotide approaches by enhancing nuclear delivery, positioning it as a potential leader in a competitive but underserved therapeutic area for genetic diseases.

Comparison to Industry Standards

• PGN-EDODM1 achieved a mean 53.7% splicing correction at 15 mg/kg, which is stated as the highest ever reported in DM1 patients, suggesting a potentially superior efficacy profile compared to other investigational therapies in the DM1 space.
• The EDO platform's ability to improve endosomal escape and increase nuclear uptake up to 98-fold for oligonucleotides represents a significant advancement over conventional 'naked oligonucleotide' approaches, which typically show poor muscle cell and nuclear penetration.
• The company's focus on addressing the root cause of DM1 by selectively binding to the pathogenic DMPK transcript aligns with the industry's shift towards precision medicine for genetic disorders, differentiating it from symptomatic treatments.

Stakeholder Impact

• Shareholders: Positive clinical data and clear development milestones could increase investor confidence and potentially lead to share price appreciation. The extended cash runway reduces immediate dilution risk.
• Patients with DM1: The investigational therapy PGN-EDODM1 offers significant hope for a disease with no approved therapies addressing the underlying cause, potentially leading to meaningful functional improvements with longer treatment.
• Employees: Continued positive clinical progress and financial stability provide job security and potential for growth within the company.
• Regulatory Authorities: The Fast Track and Orphan Drug designations indicate recognition of the unmet need and potential of PGN-EDODM1, potentially streamlining the review process.

Next Steps

• Continue dosing the 5 mg/kg cohort in the FREEDOM2 Phase 2 multiple-ascending dose study.
• Begin dosing the 10 mg/kg cohort in the FREEDOM2 study in Q1 2026.
• Report clinical results from the FREEDOM2 5 mg/kg cohort in Q1 2026.
• Report clinical results from the FREEDOM2 10 mg/kg cohort in H2 2026.
• Explore protocol amendment to dose between 10-15 mg/kg in the FREEDOM2 study.
• Continue developing the research pipeline applying the EDO platform to address underlying neuromuscular disease drivers, including Charcot-Marie-Tooth disease.

Key Dates

Recommendation

The filing presents compelling Phase 1 data for PGN-EDODM1, demonstrating unprecedented splicing correction and a favorable safety profile, which are critical indicators of therapeutic potential for Myotonic Dystrophy Type 1. The company has a clear development pathway with the ongoing FREEDOM2 Phase 2 study and a solid cash runway into 2H 2027, mitigating near-term financial risks. While functional improvements were not seen after a single dose, this is expected for a chronic condition requiring longer treatment. The strong biological activity and safety profile position PGN-EDODM1 as a promising candidate in an area of high unmet medical need, making it an attractive investment for long-term growth.

Keywords

Myotonic Dystrophy Type 1, DM1, PGN-EDODM1, EDO platform, oligonucleotide therapy, neuromuscular disease, clinical trials, splicing correction, biotechnology, pharmaceuticals