Boston, MA – [Insert Date] – PepGen Inc. (NASDAQ: PEPG), a clinical-stage biotechnology company focused on transforming the treatment of genetically defined neuromuscular diseases, has announced a significant milestone in its Phase II FREEDOM2-DM1 study. An independent Data and Safety Monitoring Board (DSMB) has unanimously recommended the progression of the study to its highest planned dosage cohort of 12.5mg/kg for PGN-EDODM1, a novel therapeutic candidate for myotonic dystrophy type 1 (DM1). This pivotal decision, made without any modifications to the existing study protocol, underscores the encouraging safety and tolerability profile of PGN-EDODM1 observed to date.
The DSMB’s recommendation is a testament to the robust safety data generated from the fully enrolled 10mg/kg cohort in the FREEDOM2 study and the ongoing open-label extension (OLE) study. Concurrently, the DSMB also approved an increase in the dosage within the OLE study to 10mg/kg from the previous 5mg/kg. This dual approval signifies a strong vote of confidence in PGN-EDODM1’s potential to safely address the complex challenges of DM1.
Myotonic dystrophy type 1 is a rare, progressive, and debilitating multisystemic genetic disorder characterized by myotonia (delayed muscle relaxation), progressive muscle weakness, and a wide range of other symptoms affecting various organs, including the heart, lungs, and gastrointestinal system. The disease is caused by a CTG trinucleotide repeat expansion in the DMPK gene, leading to the sequestration of muscleblind-like 1 (MBNL1) protein and aberrant splicing of numerous genes, ultimately contributing to the widespread cellular dysfunction observed in DM1 patients. Current treatment options are largely supportive, focusing on managing symptoms rather than addressing the underlying genetic cause.
A Promising Therapeutic Approach for Myotonic Dystrophy Type 1
PGN-EDODM1 is PepGen’s lead drug candidate, designed to address the root cause of DM1 by restoring the correct splicing of MBNL1. It utilizes a proprietary Enhanced Delivery Oligonucleotide (EDO) technology, which is engineered to efficiently deliver therapeutic oligonucleotides to target tissues, including skeletal muscle, cardiac muscle, and potentially the central nervous system. By targeting the aberrant splicing events driven by the expanded CTG repeats, PGN-EDODM1 aims to normalize gene expression and mitigate the downstream pathological consequences of the disease.
The FREEDOM2-DM1 study is a multicenter, randomized, double-blind, placebo-controlled Phase II clinical trial designed to evaluate the safety, tolerability, and preliminary efficacy of PGN-EDODM1 in adults with DM1. The study is investigating multiple dose levels of the therapeutic candidate, with the latest advancement marking the initiation of the highest planned dose.
Chronology of Advancement: A Steady March Towards Higher Doses
The journey to the current Phase II advancement has been characterized by meticulous data evaluation and a commitment to patient safety. The FREEDOM2 study has been systematically enrolling participants and progressing through dose escalation cohorts. The decision to advance to the 12.5mg/kg cohort is directly informed by the comprehensive safety analysis of the 10mg/kg cohort, which has now been fully enrolled and has completed its dosing period.
Furthermore, the safety data from the open-label extension (OLE) study has played a crucial role in shaping the DSMB’s recommendation. The OLE allows participants who have completed the placebo-controlled portion of the FREEDOM2 study to continue receiving active treatment, providing valuable long-term safety and efficacy data. Currently, a significant proportion of participants from the 5mg/kg FREEDOM2 cohort have opted to join the OLE study, contributing to the growing dataset. Specifically, six out of the eight participants from the 5mg/kg FREEDOM2 cohort have transitioned into the OLE, increasing the total enrollment in the extension study to 16 participants.
The recent approval to increase the dosage in the OLE study to 10mg/kg from 5mg/kg further validates the positive safety signals observed. This adjustment allows for the evaluation of a higher therapeutic exposure in a real-world, extended treatment setting, providing crucial insights into the long-term benefits and safety profile of PGN-EDODM1.
Supporting Data: A Foundation of Safety and Tolerability
The clinical development of PGN-EDODM1 has been marked by a consistently favorable safety profile, a critical factor for any therapeutic targeting a chronic and progressive disease like DM1. Across both the FREEDOM2 study and the OLE, PGN-EDODM1 has been generally well-tolerated by participants. Importantly, no serious adverse events (SAEs) or dose-limiting toxicities (DLTs) have been reported to date.
The repeated administration of PGN-EDODM1 at both the 5mg/kg and 10mg/kg dose levels has demonstrated no indications of cumulative toxicity. This is a significant finding, as cumulative toxicity can be a concern with chronic treatments, potentially leading to adverse effects over time. The absence of such signals suggests that the therapeutic can be administered safely over extended periods, which is essential for managing a lifelong condition like DM1.
Furthermore, the data indicates a high level of treatment adherence and patient retention. No participants in the FREEDOM2 study or the OLE have discontinued treatment due to adverse events associated with PGN-EDODM1. This high retention rate is a strong indicator of both the tolerability of the drug and the perceived benefit by the participants themselves.
PepGen anticipates reporting preliminary findings from the fully enrolled 10mg/kg FREEDOM2 cohort in November. These results are expected to provide valuable insights into the safety profile and potential efficacy signals at this dose level. Following this, data from the newly initiated 12.5mg/kg cohort is anticipated in the first half of 2027, offering a comprehensive view of the therapeutic’s performance across its intended dose range.
Official Responses: Confidence in the Therapeutic’s Potential
The announcement has been met with enthusiasm from PepGen’s leadership, who have expressed strong confidence in the ongoing development of PGN-EDODM1. James McArthur, President and CEO of PepGen, highlighted the significance of the DSMB’s recommendation.
"The DSMB’s recommendation to advance FREEDOM2 into the highest planned dose level in the study and escalate dosing in the OLE supports the encouraging safety profile of PGN-EDODM1 following multiple months of treatment," stated Mr. McArthur. "In the FREEDOM2 study, seven of eight participants in the 10mg/kg cohort have now completed dosing. We look forward to reporting additional safety, splicing, and functional data from FREEDOM2 as we continue to evaluate the potential of PGN-EDODM1 to address the root cause of disease across multiple organ systems."
Mr. McArthur’s statement underscores the dual focus of PepGen’s development strategy: not only to demonstrate safety but also to show evidence of the drug’s ability to correct the underlying molecular pathology of DM1 and translate that into functional improvements for patients. The mention of "splicing and functional data" indicates that PepGen is actively monitoring key biomarkers and clinical endpoints that reflect the drug’s mechanism of action and its potential to alleviate disease symptoms.
Implications for the Future of DM1 Treatment and PepGen’s Pipeline
The advancement of PGN-EDODM1 to the highest dose in its Phase II study represents a critical step towards potentially bringing a much-needed therapeutic option to individuals living with DM1. The consistently positive safety data, coupled with the robust mechanism of action targeting the core genetic defect, positions PGN-EDODM1 as a promising candidate for disease modification.
PepGen is actively planning for the next stages of development and intends to engage with regulatory authorities. The company plans to discuss further development plans with regulators in an end-of-Phase II meeting. This meeting is a crucial juncture where the company presents its accumulated data and outlines its proposed path forward for regulatory approval. An update from the OLE study, providing further long-term safety and efficacy insights, is anticipated by early January, which will likely inform these discussions.
The regulatory landscape for PGN-EDODM1 has been supportive. The drug has already received Orphan Drug and Fast Track designations from the U.S. Food and Drug Administration (FDA) for the treatment of DM1. These designations are granted to drugs that treat rare diseases or conditions for which there is a significant unmet medical need, and they can expedite the development and review process. More recently, the European Medicines Agency (EMA) has also awarded orphan designation for the treatment, further signaling the global recognition of the unmet need and the potential of PGN-EDODM1.
The progress of PGN-EDODM1 is also building on previous positive momentum for PepGen. In September 2025, PepGen’s stock experienced a significant surge, increasing by over 120%, following the announcement of promising results from a Phase I trial. In that trial, its investigational DM1 candidate demonstrated the highest mean splicing correction observed to date, a key indicator of the drug’s efficacy in addressing the molecular pathology of DM1. This earlier success provided strong preclinical and early clinical validation for PepGen’s oligonucleotide-based approach.
The successful completion of the Phase II study and subsequent regulatory approvals would represent a paradigm shift in the treatment of DM1, moving beyond symptomatic management to a disease-modifying therapy. This would not only profoundly impact the lives of patients and their families but also solidify PepGen’s position as a leader in the development of oligonucleotide-based therapeutics for rare neuromuscular diseases. The company’s continued focus on rigorous scientific evaluation, patient safety, and proactive engagement with regulatory bodies positions PGN-EDODM1 for a potentially transformative future in the treatment landscape of myotonic dystrophy type 1.
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