PEPG

– DSMB recommends advancement of PGN-EDODM1 into the highest dose cohort in the FREEDOM2-DM1 study, as well as FREEDOM-OLE dose escalation from 5 mg/kg to 10 mg/kg – – 10 mg/kg FREEDOM2-DM1 cohort fully enrolled, with 7 of 8 participants having completed dosing; data expected in November – – Results from 12.5 mg/kg FREEDOM2-DM1 cohort expected in 1H 2027 – – Well-funded with $117.2M of cash as of June 30, 2026, sufficient to fund operations into the fourth quarter of 2027 – BOSTON, August 06, 2026--(BUSINESS WIRE)--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 reported financial results for the quarter ended June 30, 2026 and recent corporate highlights. "During the second quarter, our team maintained a strong focus on execution as we advanced FREEDOM2 and continued preparing for our next clinical data readout," said James McArthur, PhD, President and Chief Executive Officer of PepGen. "The DSMB's recommendation to dose escalate in both FREEDOM2 and the open-label extension reflects the encouraging safety profile of PGN-EDODM1 following several months of repeat dosing. We look forward to initiating enrollment in the 12.5 mg/kg cohort shortly and sharing data from the 10 mg/kg cohort in November. We remain confident that repeat dosing has the potential to build on the clinical foundation established in the FREEDOM single-ascending dose trial as we continue evaluating the safety and benefits of PGN-EDODM1 for individuals living with DM1." Recent Program Updates PGN-EDODM1: Myotonic Dystrophy Type 1 (DM1) FREEDOM2 Phase 2 Multiple Ascending Dose (MAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: Corporate Updates In May 2026, PepGen presented a late-breaking oral and poster presentation featuring data from its PGN-EDODM1 program at the 15th International Myotonic Dystrophy Consortium (IDMC-15). The late-breaking oral session included analyses of individual patient mis-splicing data from the PGN-EDODM1 program, as well as natural history data characterizing mis-splicing in patients with DM1. Ahead of IDMC-15, PepGen's President and Chief Executive Officer, James McArthur, PhD, presented 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. Presentation materials are available on PepGen’s website under Scientific Publications. Read the full release here. Financial Results for the Three Months Ended June 30, 2026 Cash, Cash Equivalents and Marketable Securities were $117.2 million as of June 30, 2026. Based on currently planned operations, PepGen believes that its existing cash, cash equivalents, and marketable securities will be sufficient to fund its operations into the fourth quarter of 2027. Research and Development Expenses were $12.5 million for the three months ended June 30, 2026, compared to $18.4 million for the same period in 2025. General and Administrative Expenses were $6.4 million for the three months ended June 30, 2026, compared to $5.5 million for the same period in 2025. Net Loss was $17.8 million, or $(0.26) basic and diluted net loss per share, for the three months ended June 30, 2026, compared to $23.1 million, or $(0.70) basic and diluted net loss per share, for the same period in 2025. PepGen had approximately 69.3 million shares outstanding on June 30, 2026. About PGN-EDODM1 PGN-EDODM1, PepGen's investigational candidate in development for the treatment of DM1, utilizes PepGen'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 recently granted Orphan Designation for PGN-EDODM1. About PepGenPepGen 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, PepGen 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. Forward-Looking StatementsThis press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding whether repeat dosing has the potential to build on the clinical data from the FREEDOM trial, expected timelines for data reports from our FREEDOM2-DM1 trial, including the 10 mg/kg MAD cohort of FREEDOM2 trial and dose escalated 12.5 mg/kg FREEDOM2 trial as well as the OLE trial for PGN-EDODM1, initiation of the 12.5 mg/kg FREEDOM2 cohort of the FREEDOM2 study, forecasts relating to PepGen’s cash runway, and ongoing and planned regulatory timelines and interactions. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to risks related to: delays or failure to successfully initiate or complete our ongoing and planned development activities for our product candidates, including PGN-EDODM1; our ability to enroll patients in our clinical trials, including FREEDOM2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results, including for PGN-EDODM1; our product candidates, including PGN-EDODM1, may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed or approval by regulatory authorities with respect to our programs, including clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our PGN-EDODM1 program; changes in regulatory framework that are out of our control; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent reports filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses PGN-EDODM1, an investigational therapy that has not been approved for use in any country and is not intended to convey conclusions about its efficacy or safety. There is no guarantee that PGN-EDODM1 or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20260806833210/en/ Contacts Investor Contact Laurence WattsNew Street Investor [email protected] Media Contact Julia DeutschLyra Strategic Advisory, [email protected]

– FREEDOM2-DM1 5 mg/kg cohort demonstrated favorable safety, splicing and vHOT data, with the totality of results supporting the potential of the ongoing 10 mg/kg dose cohort – – The FREEDOM2 10 mg/kg cohort is fully enrolled, with data on track for 2H 2026 – – Well-funded with $132.3M of cash as of March 31, 2026, sufficient to fund operations through FREEDOM2 12.5 mg/kg MAD readout and into 2H 2027 – BOSTON, May 12, 2026--(BUSINESS WIRE)--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 reported financial results and recent corporate highlights for the quarter ended March 31, 2026, and recent corporate highlights. "We made encouraging progress during the first quarter of 2026 in our FREEDOM2-DM1 trial. The 5 mg/kg cohort — the initial dose cohort — demonstrated a favorable tolerability profile and promising efficacy trends, reinforcing our confidence in PGN-EDODM1's potential at higher doses," said James McArthur, PhD, President and Chief Executive Officer of PepGen. "Enrollment in the 10 mg/kg cohort is now complete and we remain on track to report data in the second half of this year. With funding in place through the 10 and 12.5 mg/kg cohorts, we are well positioned to continue dose escalating and deliver on the promise of this program for the DM1 community." Recent Program Updates PGN-EDODM1: Myotonic Dystrophy Type 1 (DM1) FREEDOM2 Phase 2 Multiple Ascending Dose (MAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: PepGen reported promising topline results from the 5 mg/kg MAD cohort, demonstrating favorable safety, splicing and vHOT data. The Company believes the totality of safety and efficacy results support the potential of PGN-EDODM1 in the ongoing 10 mg/kg dose cohort. Read the full release here. The Company has fully enrolled the 10 mg/kg MAD cohort of FREEDOM2. PepGen expects to report data from this cohort in the second half of 2026, with data from the 12.5 mg/kg cohort anticipated in 2027. PepGen has currently enrolled 13 patients in the open label extension (OLE) at 5 mg/kg, including 6 patients from FREEDOM2, with no patient discontinuations. The Company has received regulatory clearance to initiate the FREEDOM2 trial in South Korea, Australia, and New Zealand. Sites are currently open and active in Canada, the UK and South Korea, with plans to open sites in New Zealand and Australia. The U.S. Food and Drug Administration (FDA) placed a partial clinical hold on the FREEDOM2 study. The partial clinical hold questions raised by the FDA relate to previously submitted preclinical pharmacology and toxicology studies. The timing of the ongoing FREEDOM2 clinical study has not been impacted. The Company continues to work with the FDA to address the Agency’s questions as quickly as possible. Financial Results for the Three Months Ended March 31, 2026 Cash, Cash Equivalents and Marketable Securities were $132.3 million as of March 31, 2026. Based on currently planned operations, the Company believes that its existing cash, cash equivalents, and marketable securities will be sufficient to fund its operations into the second half of 2027. Research and Development Expenses were $13.0 million for the three months ended March 31, 2026, compared to $25.4 million for the same period in 2025. General and Administrative Expenses were $5.9 million for the three months ended March 31, 2026, compared to $5.9 million for the same period in 2025. Net Loss was $17.8 million, or $(0.26) basic and diluted net loss per share, for the three months ended March 31, 2026, compared to $30.2 million, or $(0.92) basic and diluted net loss per share, for the same period in 2025. PepGen had approximately 69.2 million shares outstanding on March 31, 2026. 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. 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 muscleblind-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. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding the therapeutic potential and safety profile of PGN-EDODM1 based on data from the 5, 10 and 15 mg/kg cohorts of the single dose FREEDOM-DM1 study and data from 5 mg/kg cohort of the multi-dose FREEDOM2-DM1 study, expected timelines for data reports from our FREEDOM2-DM1 trial, forecasts relating to PepGen’s cash runway, and ongoing and planned regulatory interactions, including the potential timing and successful resolution of questions from the FDA relating to the partial clinical hold. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to risks related to: delays or failure to successfully initiate or complete our ongoing and planned development activities for our product candidates, including PGN-EDODM1; our ability to enroll patients in our clinical trials, including FREEDOM2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results, including for PGN-EDODM1; our product candidates, including PGN-EDODM1, may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed or approval by regulatory authorities with respect to our programs, including release of the partial clinical hold placed by the FDA and/or clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our FREEDOM2 program; changes in regulatory framework that are out of our control; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent reports filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses PGN-EDODM1, an investigational therapy that has not been approved for use in any country, and is not intended to convey conclusions about its efficacy or safety. There is no guarantee that PGN-EDODM1 or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20260512245445/en/ Contacts Investor Contact Laurence Watts New Street Investor Relations [email protected] Media Contact Julia Deutsch Lyra Strategic Advisory, LLC [email protected]

– PGN-EDODM1 was generally well-tolerated with all adverse events mild or moderate and no serious adverse events reported – – Mean splicing correction of 7.3% observed with PGN-EDODM1 (n=6) versus 6.8% with placebo (n=2); Excluding one outlier patient, treatment group demonstrated mean splicing correction of 22.9% (n=5) – – Promising trends observed in vHOT in the PGN-EDODM1 treated group – – Company on track to report clinical data from 10 mg/kg multiple dose cohort in 2H 2026 with sufficient cash expected to fund operations into 2H 2027– – Conference call scheduled today at 4:30 p.m. ET – BOSTON, March 30, 2026--(BUSINESS WIRE)--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 promising clinical data from the 5 mg/kg multiple ascending dose cohort (MAD) of the ongoing Phase 2 FREEDOM2-DM1 trial in patients with myotonic dystrophy type 1 (DM1). The Company believes the totality of safety and efficacy results support the potential of the ongoing 10 mg/kg dose cohort, with clinical results expected in the second half of 2026. "We are excited to share data from the lowest dose cohort in our multiple ascending dose study of PGN-EDODM1 in patients with DM1," said Paul Streck, MD, EVP Research and Development. "Overall, we are encouraged by the favorable safety and tolerability profile, and the positive trends exhibited with splicing improvement and vHOT. We look forward to reporting data from the ongoing 10 mg/kg multiple ascending dose cohort of FREEDOM2, which is more than halfway enrolled and remains on track to read out in the second half of this year." FREEDOM2 Results for the 5 mg/kg (n=8) Dose Cohort FREEDOM2 is a Phase 2 MAD, randomized, placebo-controlled clinical trial evaluating PGN-EDODM1 in patients with DM1, with planned dose escalation up to 12.5 mg/kg. The 5 mg/kg cohort enrolled eight patients, who received PGN-EDODM1 or placebo (randomized 6:2) every four weeks over a 12-week period. Key endpoints include safety, splicing correction and functional outcome measures. The data cutoff was March 4, 2026. Splicing, Muscle Tissue Concentration and Functional Data: Patients (n=6) treated with PGN-EDODM1 at 5 mg/kg demonstrated a mean splicing correction of 7.3%, compared to 6.8% in placebo-treated patients (n=2). Excluding an outlier, patients showed a mean splicing correction of 22.9%. The outlier patient exhibited a worsening in splicing correction (70.8%), reducing the overall group mean to 7.3%. Middle finger vHOT in the treatment group showed a positive trend of improvement versus a worsening observed in the placebo group. Both returned to baseline at Week 16. Mean muscle tissue concentrations of PGN-EDODM1 available in 5 of 6 treated patients were 158 ng/g, as measured approximately one week after the fourth dose in the MAD study; one concentration readout remains pending. No meaningful improvements were observed in 10-meter walk/run test (10MWRT) or handgrip strength at the starting PGN-EDODM1 dose of 5 mg/kg. Safety and Tolerability Data: PGN-EDODM1 was generally well-tolerated, with no serious adverse events (SAEs), all related treatment emergent adverse events (TEAEs) reported as mild and non-related TEAEs reported as mild or moderate Nausea was the most common TEAE No treatment-related discontinuations No TEAEs related to renal function and no signs of cumulative toxicity The Company is actively dosing the 10 mg/kg MAD cohort of FREEDOM2, with 5 of 8 patients receiving up to three doses of PGN-EDODM1, and expects to report data in the second half of 2026. In addition, 12 patients have currently enrolled in the open label extension (OLE) at 5 mg/kg, including 5 patients from FREEDOM2. Conference Call Details To access the live audio webcast for today’s conference call beginning at 4:30 p.m. ET, please visit PepGen’s investor website at investors.pepgen.com. An archived replay of the webcast will be available on the Company’s website following the event. 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 recently granted Orphan Designation for PGN-EDODM1. 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. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding various data demonstrating promising results that support the safety and clinical potential of PGN-EDODM1 as a treatment for DM1 and expected timelines for the data report from the 10 mg/kg cohort of our FREEDOM2-DM1 trial, our expected cash runway, the design, initiation and conduct of clinical trials, including expected timelines for our FREEDOM2-DM1 trial, and ongoing and planned regulatory interactions. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to risks related to: delays or failure to successfully initiate or complete our ongoing and planned development activities for PGN-EDODM1; our ability to enroll patients in our clinical trials, including FREEDOM2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results for PGN-EDODM1; that PGN-EDODM1 may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed or approval by regulatory authorities with respect to our programs, including release of the partial clinical hold or clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our FREEDOM2 program; changes in regulatory framework that are out of our control; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent reports filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses PGN-EDODM1, an investigational therapy that has not been approved for use in any country, and is not intended to convey conclusions about its efficacy or safety. There is no guarantee that PGN-EDODM1 or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20260330100190/en/ Contacts Investor Contact Laurence Watts New Street Investor Relations [email protected] Media Contact Julia Deutsch Lyra Strategic Advisory [email protected]

– FREEDOM2-DM1 5 mg/kg cohort data expected in Q1 2026 – – Patient dosing in the FREEDOM2 10 mg/kg cohort is proceeding in Canada and the UK, with data expected in 2H 2026 – – FREEDOM2 trial open in South Korea, Australia, and New Zealand – – Well-funded with $148.5M of cash as of December 31, 2025, sufficient to fund operations into the second half of 2027 – BOSTON, March 04, 2026--(BUSINESS WIRE)--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 reported financial results for the quarter and year-ended December 31, 2025, and recent corporate highlights. "2025 was a transformative year for PepGen as the Phase 1 FREEDOM trial delivered compelling data that set a new benchmark for splicing correction in DM1, reinforced our conviction in PGN-EDODM1 as a potential best-in-class treatment, and further demonstrated the differentiated potential of our EDO platform," said James McArthur, PhD, President and Chief Executive Officer of PepGen. "After a single dose, we observed robust target engagement beginning at the lowest dose of 5 mg/kg — a finding that exceeded our expectations and underscored the potency of our drug candidate. PGN-EDODM1 was generally well-tolerated across doses, and based on the totality of FREEDOM data, we believe that doses of 10 mg/kg could potentially offer a best-in-class treatment option for people living with this serious disease." Dr. McArthur continued: "As we prepare for the 5 mg/kg dose cohort readout from our ongoing randomized, placebo-controlled multiple ascending dose Phase 2 FREEDOM2 study later this quarter, we are focused on building upon the robust muscle oligonucleotide levels and splicing correction observed in FREEDOM, with the goal of translating sustained exposure into meaningful functional benefit. Following the Data Safety Monitoring Board’s recommendation to dose escalate, we are actively dosing the 10 mg/kg cohort in FREEDOM2 – four patients have been dosed, receiving up to two doses. PepGen is entering this new year with strong momentum and a clear path toward potentially delivering a meaningful new treatment for the DM1 community." Recent Program Updates PGN-EDODM1: Myotonic Dystrophy Type 1 (DM1) FREEDOM2 Phase 2 Multiple Ascending Dose (MAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: The Company expects to report results from the 5 mg/kg cohort of the FREEDOM2 trial in the first quarter of 2026. After reviewing safety data from the 5 mg/kg cohort, the Data Safety Monitoring Board (DSMB) recommended escalating to the 10 mg/kg dose. PepGen has since dosed 50% of patients (4/8) in the 10 mg/kg cohort with up to two doses. The Company remains on track to report results from the 10 mg/kg cohort in the second half of 2026. Informed by the prior FREEDOM results, PepGen has amended the FREEDOM2 protocol to provide the option to dose up to 12.5 mg/kg. Patients from the FREEDOM and FREEDOM2 studies in Canada are continuing into the Open Label Extension (OLE) study. The Company has received regulatory clearance for the OLE study in the UK and intends to open the OLE study in all geographies where FREEDOM2 is open. The Company has recently received regulatory clearance to initiate the FREEDOM2 trial in South Korea, Australia, and New Zealand. Sites are currently enrolling in Canada, the UK and South Korea, with plans to open sites in New Zealand and Australia. The U.S. Food and Drug Administration (FDA) has placed a partial clinical hold on the FREEDOM2 study. The partial clinical hold questions raised by FDA relate to previously submitted preclinical pharmacology and toxicology studies. The partial clinical hold did not cite any questions regarding blinded clinical data from the Phase 1 FREEDOM study previously submitted to the FDA in order to initiate the FREEDOM2 study in the U.S. The Company is committed to working with the FDA to address the Agency’s questions as quickly as possible. Other FREEDOM Updates: In October 2025, PepGen’s data were featured in two oral presentations at the 30th Annual International Congress of the World Muscle Society (WMS). One presentation included previously reported positive FREEDOM-DM1 Phase 1 clinical data. In October 2025, the Company gave an oral presentation at the Oligonucleotide Therapeutics Society (OTS) Annual Meeting. The presentation reviewed the use of its Enhanced Delivery Oligonucleotide (EDO) Platform to develop a treatment for DM1 and included a review of the FREEDOM clinical data. 2026 MDA Conference Update The Company will present unblinded final results from FREEDOM-DM1 — its Phase 1, placebo-controlled single ascending dose study of PGN-EDODM1 in DM1 adult patients — in oral and poster presentations at the 2026 Muscular Dystrophy Association (MDA) Clinical & Scientific Conference, being held March 8–11, 2026 in Orlando, Florida. Key study findings include: Efficacy: PGN-EDODM1 demonstrated greater than dose-proportional increases in muscle tissue concentration and splicing correction across all doses at Day 28. Mean splicing correction reached unprecedented levels after a single dose, achieving 12.3%, 29.1%, and 53.7% at 5 mg/kg (n=6), 10 mg/kg (n=5), and 15 mg/kg (n=6), respectively. Safety: PGN-EDODM1 was generally well-tolerated across all doses; treatment-emergent adverse events (TEAEs) were mild to moderate, transient, and required no intervention (except one patient in the 15 mg/kg cohort, managed with oral antihistamines). No electrolyte-related TEAEs were observed, and magnesium levels remained within normal range across all doses. No renal biomarker-related TEAEs were observed at 5 or 10 mg/kg. Post-unblinding, transient moderate albuminuria increases at the 15 mg/kg dose and transient mild albuminuria increases at 10 mg/kg were apparent — both resolving to normal within two to seven days with no clinical symptoms or need for intervention. Following the conference, the presentations presented at the 2026 MDA Clinical & Scientific Conference will be available on PepGen’s website under Scientific Publications. Corporate Updates In December 2025, PepGen appointed Joseph Vittiglio, Esq., as Chief Business and Legal Officer. Mr. Vittiglio brings more than two decades of executive leadership experience across legal, compliance, corporate development, and corporate governance within public biotechnology companies. He joins PepGen after providing consulting support to the Company in 2025. In November 2025, the Company announced that the United States Patent and Trademark Office (USPTO) has issued the Company a new composition of matter patent covering PGN-EDODM1, which leverages PepGen’s proprietary EDO platform, including its unique peptide and linker chemistry. This newly issued composition of matter patent, which serves as a cornerstone of the Company’s expanding patient portfolio, is expected to provide exclusivity for PGN-EDODM1 in the United States into second half of 2042, with the possibility of patent term extension following a potential new drug application and approval by FDA of PGN-EDODM1. Financial Results for the Three Months and Year Ended December 31, 2025 Cash, Cash Equivalents and Marketable Securities were $148.5 million as of December 31, 2025. Based on currently planned operations, the Company believes that its existing cash, cash, equivalents, and marketable securities will be sufficient to fund its operations into the second half of 2027. Research and Development Expenses were $13.9 million for the three months ended December 31, 2025, compared to $19.0 million for the same period in 2024. Research and development expenses were $71.0 million for the year ended December 31, 2025, compared to $76.5 million for the same period in 2024. General and Administrative Expenses were $5.9 million for the three months ended December 31, 2025, compared to $5.4 million for the same period in 2024. General and administrative expenses were $22.6 million for the year ended December 31, 2025, compared to $21.3 million for the same period in 2024. Net Loss was $18.3 million, or $(0.27) basic and diluted net loss per share, for the three months ended December 31, 2025, compared to $22.2 million, or $(0.68) basic and diluted net loss per share, for the same period in 2024. Net loss was $89.7 million, or $(2.12) basic and diluted net loss per share, for the year ended December 31, 2025, compared to $90.0 million, or $(2.85) basic and diluted net loss per share, for the same period in 2024. PepGen had approximately 68,874,944 shares outstanding as of December 31, 2025. 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 recently granted Orphan Designation for PGN-EDODM1. 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. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding the therapeutic potential and safety profile of PGN-EDODM1 based on data from the 5, 10 and 15 mg/kg cohorts of the FREEDOM-DM1 study, our expectations regarding 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 design and conduct of clinical trials with our candidates, including expected timelines for the initial data report from our FREEDOM2-DM1 trial and the potential to extend dosing to the 12.5 mg/kg dose level, the potential for any functional improvements that may result from robust splicing correction with PGN-EDODM1, dose-dependent increases in splicing suggesting that PGN-EDODM1 is getting into the muscle and effectively binding to the target, the potential for PGN-EDODM1 to offer a best-in-class treatment option, the potential for future patent term extension, forecasts relating to our cash runway, and ongoing and planned regulatory interactions and ongoing and planned regulatory interactions, including the potential timing and successful resolution of questions from the FDA relating to the partial clinical hold. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to risks related to: delays or failure to successfully initiate or complete our ongoing and planned development activities for our product candidates, including PGN-EDODM1; our ability to enroll patients in our clinical trials, including FREEDOM2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results, including for PGN-EDODM1; our product candidates, including PGN-EDODM1, may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed with planned clinical studies or approval by regulatory authorities with respect to our investigational drug candidates, including release of the partial clinical hold placed by FDA on the FREEDOM2 study, or other regulatory feedback requiring modifications to our development programs, including release of the partial clinical hold or clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our FREEDOM2 program; changes in regulatory framework that are out of our control; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent reports filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses PGN-EDODM1, an investigational therapy that has not been approved for use in any country, and is not intended to convey conclusions about its efficacy or safety. There is no guarantee that PGN-EDODM1 or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20260304670027/en/ Contacts Investor Contact Laurence Watts New Street Investor Relations [email protected] Media Contact Julia Deutsch Lyra Strategic Advisory, LLC [email protected]

– FREEDOM-DM1 15 mg/kg cohort demonstrated the highest mean splicing correction reported to date in DM1 patients – – FREEDOM2-DM1 5 mg/kg cohort on track to readout in Q1 2026, with all patients enrolled and having received at least one dose – – Recent $115 million financing extends cash runway into the second half of 2027 – BOSTON, November 12, 2025--(BUSINESS WIRE)--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 reported financial results and recent corporate highlights for the quarter ended September 30, 2025. "This quarter was defined by the strong results from the 15 mg/kg cohort of our FREEDOM study, which showed unprecedented levels of splicing correction following a single dose," said James McArthur, PhD, President and Chief Executive Officer of PepGen. "With the key objectives of the FREEDOM study achieved, we are carrying this momentum forward as we advance our multiple ascending dose trial, FREEDOM2. Because mis-splicing is the underlying cause of DM1, we believe that the high levels of splicing correction we achieved have the potential to translate into meaningful functional improvements across key outcome measures, including myotonia and muscle weakness, over time; and we are eager to demonstrate this in FREEDOM2. Bolstered by our recent financing, we are now well positioned to advance FREEDOM2 and further validate the potential of PGN-EDODM1 to become a best-in-class treatment for individuals living with DM1. We look forward to sharing data from the 5 mg/kg multi-dose cohort in the first quarter of next year." Recent Program Updates PGN-EDODM1: Myotonic Dystrophy Type 1 (DM1) FREEDOM Phase 1 Single Ascending Dose (SAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: The Company reported topline results from the 15 mg/kg cohort of PGN-EDODM1, demonstrating a mean splicing correction of 53.7% following a single 15 mg/kg dose—substantially higher than any previously reported splicing correction in DM1 patients and with all patients showing improvement in splicing. PGN-EDODM1 was generally well tolerated at this dose, with drug-related adverse events mild or moderate in severity. For additional details, read the full press release here. FREEDOM2 Phase 2 Multiple Ascending Dose (MAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: All patients in the 5 mg/kg cohort of the FREEDOM2 trial have been enrolled and have received at least one dose. The Company remains on track to report results from the 5 mg/kg cohort in the first quarter of 2026 and expects to initiate dosing in the 10 mg/kg cohort during the same quarter. The Company remains on track to report results from the 10 mg/kg cohort in 2H 2026. Corporate Updates In September 2025, PepGen closed an underwritten public offering, raising $115 million in aggregate gross proceeds before deducting underwriting discounts, commissions, and offering expenses. Based on current plans, these proceeds extend the Company’s cash runway into the second half of 2027. In October 2025, the Company’s data were featured in two oral presentations at the 30th Annual International Congress of the World Muscle Society (WMS). One presentation included the previously reported positive FREEDOM-DM1 Phase 1 clinical data. The presentations presented are available on PepGen’s website under Scientific Publications. In October 2025, PepGen gave an oral presentation at the Oligonucleotide Therapeutics Society (OTS) Annual Meeting. The presentation reviewed the use of its Enhanced Delivery Oligonucleotide (EDO) Platform to develop a treatment for DM1 and included a review of the FREEDOM clinical data. The presentation presented is available on PepGen’s website under Scientific Publications. Financial Results for the Three Months Ended September 30, 2025 Cash, Cash Equivalents and Marketable Securities were $163.7 million as of September 30, 2025. Based on currently planned operations, the Company believes that its existing cash, cash equivalents, and marketable securities will be sufficient to fund its operations into the second half of 2027. Research and Development Expenses were $13.4 million for the three months ended September 30, 2025, compared to $17.7 million for the same period in 2024. General and Administrative Expenses were $5.2 million for the three months ended September 30, 2025, compared to $5.4 million for the same period in 2024. Net Loss was $18.0 million, or $(0.52) basic and diluted net loss per share, for the three months ended September 30, 2025, compared to $21.4 million, or $(0.66) basic and diluted net loss per share, for the same period in 2024. PepGen had approximately 68.7 million shares outstanding on September 30, 2025. 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 myotonic 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. 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. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding the therapeutic potential and safety profile of PGN-EDODM1 based on data from the 5, 10 and 15 mg/kg cohorts of the FREEDOM-DM1 study, our expectations regarding 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 design and conduct of clinical trials with our candidates, including expected timelines for the initial data report from our FREEDOM2-DM1 trial, the potential for any functional improvements that may result from robust splicing correction with PGN-EDODM1, forecasts relating to our cash runway, and ongoing and planned regulatory interactions. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: delays or failure to successfully initiate or complete our ongoing and planned development activities for our product candidates, including PGN-EDODM1; our ability to enroll patients in our clinical trials, including FREEDOM2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results, including for PGN-EDODM1; our product candidates, including PGN-EDODM1, may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed or approval by regulatory authorities with respect to our programs, including clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our FREEDOM and FREEDOM2 clinical trials; changes in regulatory framework that are out of our control; our ability to obtain, maintain and protect our intellectual property; our ability to enforce our patents against infringers and defend our patent portfolio against challenges from third parties; competition from others developing therapies for indications we are pursuing; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent reports filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses PGN-EDODM1, an investigational therapy that has not been approved for use in any country, and is not intended to convey conclusions about its efficacy or safety. There is no guarantee that PGN-EDODM1 or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20251112398555/en/ Contacts Investor Contact Laurence Watts New Street Investor Relations [email protected] Media Contact Julia Deutsch Lyra Strategic Advisory, LLC [email protected]

– Last patient dosed in 15 mg/kg cohort of FREEDOM-DM1; on track to report topline data from study in early Q4 2025 – – FREEDOM to conclude with the 15 mg/kg cohort based on splicing and safety data observed to date; clinical sites will begin transitioning to the Phase 2 multiple ascending dose study, FREEDOM2-DM1 – BOSTON, August 07, 2025--(BUSINESS WIRE)--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 reported financial results and recent corporate highlights for the quarter ended June 30, 2025. "This quarter, we made further progress in the development of our promising myotonic dystrophy type 1 program, PGN-EDODM1. With class-leading mean mis-splicing correction following a single 10 mg/kg dose, we believe PGN-EDODM1 has the potential to become a best-in-class treatment for patients with DM1," said James McArthur, PhD, President and CEO of PepGen. "Having recently completed patient dosing in the 15 mg/kg arm of our single ascending dose FREEDOM trial (PGN-EDODM1-101), we look forward to sharing topline data from this cohort in early Q4 2025. Furthermore, the efficacy and emerging safety profile of PGN-EDODM1 supports our decision to conclude the FREEDOM trial with the 15 mg/kg single dose cohort, with the additional benefit of being able to now transition clinical sites to the FREEDOM2 trial (PGN-EDODM1-102), our multiple ascending dose trial. Our FREEDOM2 trial is designed to demonstrate that sustained mis-splicing correction with multiple doses of PGN-EDODM1 can produce meaningful functional improvements in patients with DM1. We’re looking forward to reporting results from the initial dose cohort of FREEDOM2 in the first quarter of 2026." Recent Program Updates PGN-EDODM1: Myotonic Dystrophy Type 1 (DM1) FREEDOM Phase 1 Single Ascending Dose (SAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: The Company has completed patient dosing in the 15 mg/kg cohort of the FREEDOM trial and remains on track to report safety, 28-day splicing and functional benefit data from the 15 mg/kg cohort in early fourth quarter of 2025. Based on the robust splicing correction observed at the 5 and 10 mg/kg dose cohorts and the totality of the blinded safety data to date, the Company has decided to conclude dose escalation in the FREEDOM trial with the 15 mg/kg cohort. PepGen will now redirect resources to the FREEDOM2 trial and begin transitioning open clinical sites to the multiple ascending dose (MAD) study. FREEDOM2 Phase 2 Multiple Ascending Dose (MAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: The Company expects to report results from the 5 mg/kg cohort of the FREEDOM2 trial in the first quarter of 2026. Corporate Updates In May 2025, PepGen appointed Kasra Kasraian, PhD, as Chief Technology Officer. Dr. Kasraian brings over 25 years of experience in product and process development, CMC strategy, and technical operations, spanning small and large molecules, as well as cell and gene therapies. In May 2025, the Company presented an oral presentation and two posters at the 2025 Myotonic Dystrophy Foundation (MDF) Conference. PepGen also presented at the 5th Edition of Euro-DyMA's Pharma Day, held in conjunction with the MDF Conference. These presentations highlighted the recently announced FREEDOM clinical data in DM1, as well as proof-of-mechanism preclinical results for PGN-EDODM1. Financial Results for the Three Months Ended June 30, 2025 Cash, Cash Equivalents and Marketable Securities were $74.7 million as of June 30, 2025. Based on currently planned operations, the Company believes that its existing cash, cash, equivalents, and marketable securities will be sufficient to fund its operations into the second quarter of 2026. Research and Development Expenses were $18.4 million for the three months ended June 30, 2025, compared to $25.1 million for the same period in 2024. General and Administrative Expenses were $5.5 million for the three months ended June 30, 2025, compared to $5.4 million for the same period in 2024. Net Loss was $23.1 million, or $(0.70) basic and diluted net loss per share, for the three months ended June 30, 2025, compared to $28.3 million, or $(0.87) basic and diluted net loss per share, for the same period in 2024. PepGen had approximately 32.8 million shares outstanding on June 30, 2025. About PGN-EDODM1 PGN-EDODM1, PepGen's investigational candidate in development for the treatment of myotonic dystrophy Type 1 (DM1), utilizes the Company's proprietary Enhanced Delivery Oligonucleotide (EDO) technology to restore the normal splicing function of MBNL1, a key RNA splicing protein. PGN-EDODM1 is designed to directly address the deleterious effects of cytosine-uracil-guanine (CUG) repeat expansion in the dystrophia myotonic protein kinase (DMPK) transcripts which sequester MBNL1, by binding to the pathogenic CUG trinucleotide repeat expansion present in the DMPK transcripts, disrupting the binding between the CUG repeat expansion and MBNL1. DM1 is a progressively disabling, life-shortening genetic disorder. DM1 is estimated to affect 40,000 people in the United States, and over 74,000 people in Europe. 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. About PepGen PepGen is 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. PepGen’s 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, our goal is to generate 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. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding the therapeutic potential and safety profile of our lead product candidate, including, based on early data, PGN-EDODM1, the magnitude of the cost savings from concluding the FREEDOM 1 trial with the 15 mg/kg cohort, the ability to complete enrollment and dose escalation in the FREEDOM2 trial, the expected timing for additional data reports from our FREEDOM Phase 1 trial and FREEDOM2 trial, ongoing and planned regulatory interactions, and our financial resources and expected cash runway. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to risks related to: delays or failure to successfully initiate or complete our ongoing and planned development activities for our current or future product candidates, including PGN-EDODM1; our ability to enroll patients in our clinical trials, including FREEDOM and FREEDOM2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results, including for PGN-EDODM1; our current and future product candidates, including PGN-EDODM1, may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed or approval by regulatory authorities with respect to our programs, including clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our FREEDOM and FREEDOM2 clinical trials; changes in regulatory framework that are out of our control; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent annual report on Form 10-K and quarterly report on Form 10-Q that are filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses our lead product candidate, PGN-EDODM1, an investigational therapy that has not been approved for use in any country and is not intended to convey conclusions about its efficacy or safety. There is no guarantee that PGN-EDODM1, or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20250807282316/en/ Contacts Investor Contact Laurence Watts New Street Investor Relations [email protected] Media Contact Julia Deutsch Lyra Strategic Advisory, LLC [email protected]

– Reported positive DM1 patient data with mean splicing correction of 29.1% following a single dose of PGN-EDODM1 at 10 mg/kg – – FREEDOM-DM1 data from 15 mg/kg cohort expected in the second half of 2025 – – CONNECT1-EDO51 data from 10 mg/kg cohort expected in the third quarter of 2025 – BOSTON, May 08, 2025--(BUSINESS WIRE)--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 reported financial results and recent corporate highlights for the quarter ended March 31, 2025. "Our EDO platform’s unique ability to efficiently deliver oligonucleotides into the nuclei of cells is the foundation of our differentiated pipeline, with promising clinical data from two programs underscoring what we believe to be the broad potential of our technology," said James McArthur, PhD, President and CEO of PepGen. "This is a pivotal and catalyst-rich 12 months for PepGen and for our DM1 and DMD clinical programs. Following the highly encouraging initial results from our FREEDOM-DM1 study reported in February, demonstrating potentially best-in-class splicing correction after a single therapeutic dose, we look forward to sharing data from the 15 mg/kg cohort in the second half of the year. We also expect to report dystrophin production data from the 10 mg/kg cohort of our CONNECT1-EDO51 study in patients with DMD in the third quarter. Collectively, we believe these data will build on the body of evidence supporting our platform’s promise. Additionally, during the first quarter, we have undertaken various measures to extend our cash runway while prioritizing delivering on our key clinical milestones." Recent Program Updates PGN-EDODM1: Myotonic Dystrophy Type 1 (DM1) Phase 1 FREEDOM-DM1 Single Ascending Dose (SAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: In February, the Company reported positive initial clinical data from the 5 mg/kg and 10 mg/kg dose cohorts from the ongoing FREEDOM trial. At day 28 following a single dose, PGN-EDODM1 was observed to have a favorable emerging safety profile and robust, dose-dependent splicing correction in the 5 and 10 mg/kg dose cohorts. PepGen expects to report safety, 28-day splicing and functional benefit data from the 15 mg/kg cohort during the second half of 2025. Phase 2 FREEDOM2-DM1 Multiple Ascending Dose (MAD) Randomized, Placebo-Controlled Clinical Trial of PGN-EDODM1: The Company expects to report results from the 5 mg/kg cohort of the FREEDOM2 trial in the first quarter of 2026. PGN-EDO51: Duchenne Muscular Dystrophy (DMD) Phase 2 CONNECT1-EDO51 Open-Label MAD Clinical Trial of PGN-EDO51: PepGen expects to report additional safety as well as dystrophin production data from the 10 mg/kg cohort of the CONNECT1 trial in DMD patients in the third quarter of 2025. Phase 2 CONNECT2-EDO51 MAD Clinical Trial of PGN-EDO51: In March 2025, the Company announced its voluntary decision to pause the Phase 2 CONNECT2 trial in DMD patients until it can review results from the 10 mg/kg cohort in the ongoing Phase 2 CONNECT1 trial. Corporate Updates In March 2025, PepGen announced that Lisa Wyman and Mitchell H. Finer, PhD, joined the Company’s Board of Directors. Each are industry veterans bringing decades of executive and operational experience in life sciences to the Company. In March 2025, the Company gave two oral presentations and presented five posters at the 2025 Muscular Dystrophy Association (MDA) Clinical & Scientific Conference. The oral presentations featured data from the ongoing CONNECT1 clinical trial in DMD and the FREEDOM clinical trial in DM1. In May 2025, the Company made an oral presentation and presented two posters at the 2025 Myotonic Dystrophy Foundation (MDF) Conference. PepGen also presented at the 5th Edition of Euro-DyMA's Pharma Day, held in conjunction with the MDF Conference. These presentations highlighted the recently announced FREEDOM clinical data in DM1, as well as proof-of-mechanism preclinical results for PGN-EDODM1. Financial Results for the Three Months Ended March 31, 2025 Cash, Cash Equivalents and Marketable Securities were $97.8 million as of March 31, 2025. Based on currently planned operations, the Company believes that its existing cash, cash, equivalents, and marketable securities will be sufficient to fund its operations for at least 12 months from the date of this release. Research and Development Expenses were $25.4 million for the three months ended March 31, 2025, compared to $14.7 million for the same period in 2024. General and Administrative Expenses were $5.9 million for the three months ended March 31, 2025, compared to $5.1 million for the same period in 2024. Net Loss was $30.2 million, or $(0.92) basic and diluted net loss per share, for the three months ended March 31, 2025, compared to $18.0 million, or $(0.63) basic and diluted net loss per share, for the same period in 2024. PepGen had approximately 32.7 million shares outstanding on March 31, 2025. Upcoming Potential Milestones 3Q 2025: CONNECT1-EDO51 data from 10 mg/kg cohort expected 2H 2025: FREEDOM-DM1 data from 15 mg/kg cohort expected 1Q 2026: FREEDOM2-DM1 data from the 5 mg/kg cohort expected About PGN-EDODM1 PGN-EDODM1, PepGen's investigational candidate in development for the treatment of DM1, utilizes the Company's proprietary Enhanced Delivery Oligonucleotide (EDO) technology to deliver a therapeutic oligonucleotide that is designed to restore the normal splicing function of MBNL1, a key RNA splicing protein. DM1 is a progressively disabling, life-shortening genetic disorder. DM1 is estimated to affect 40,000 people in the United States, and over 74,000 people in Europe. 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. About PGN-EDO51 PGN-EDO51, PepGen's investigational candidate in development for the treatment of DMD, utilizes the Company's proprietary EDO technology to deliver a therapeutic oligonucleotide that is designed to target the root cause of this devastating disease. PGN-EDO51 is designed to skip exon 51 of the dystrophin transcript, an established therapeutic target for approximately 13% of DMD patients, thereby aiming to restore the open reading frame and enabling the production of a truncated, yet functional dystrophin protein. The U.S. Food and Drug Administration has granted PGN-EDO51 both Orphan Drug and Rare Pediatric Disease Designations for the treatment of patients with DMD amenable to an exon-51 skipping approach. About PepGen PepGen is 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. PepGen’s 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, we are 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. Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended. These statements may be identified by words such as "aims," "anticipates," "believes," "could," "estimates," "expects," "forecasts," "goal," "intends," "may," "plans," "possible," "potential," "seeks," "will," and variations of these words or similar expressions that are intended to identify forward-looking statements. Any such statements in this press release that are not statements of historical fact may be deemed to be forward-looking statements. These forward-looking statements include, without limitation, statements regarding the therapeutic potential and safety profile of our product candidates, including, based on early data, PGN-EDODM1 and PGN-EDO51, the expected timing for additional data reports from our FREEDOM Phase 1 trial and CONNECT1 Phase 2 trial and initial data from our FREEDOM2 Phase 2 trial, ongoing and planned regulatory interactions, and our financial resources and expected cash runway. Any forward-looking statements in this press release are based on current expectations, estimates and projections only as of the date of this release and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to risks related to: delays or failure to successfully initiate or complete our ongoing and planned development activities for our product candidates, including PGN-EDODM1 and PGN-EDO51; our ability to enroll patients in our clinical trials, including FREEDOM, FREEDOM2 and CONNECT2; that our interpretation of clinical and preclinical study results may be incorrect, or that we may not observe the levels of therapeutic activity in clinical testing that we anticipate based on prior clinical or preclinical results, including for PGN-EDODM1 and PGN-EDO51; our product candidates, including PGN-EDODM1 and PGN-EDO51, may not be safe and effective or otherwise demonstrate safety and efficacy in our clinical trials; adverse outcomes from our regulatory interactions, including delays in regulatory review, clearance to proceed or approval by regulatory authorities with respect to our programs, including clearance to commence planned clinical studies of our product candidates, or other regulatory feedback requiring modifications to our development programs, including in each case with respect to our FREEDOM, FREEDOM2, CONNECT1 and CONNECT2 clinical trials; changes in regulatory framework that are out of our control; unexpected increases in the expenses associated with our development activities or other events that adversely impact our financial resources and cash runway; and our dependence on third parties for some or all aspects of our product manufacturing, research and preclinical and clinical testing. Additional risks concerning PepGen’s programs and operations are described in our most recent annual report on Form 10-K and quarterly report on Form 10-Q that are filed with the SEC. PepGen explicitly disclaims any obligation to update any forward-looking statements except to the extent required by law. This release discusses PGN-EDODM1 and PGN-EDO51, investigational therapies that have not been approved for use in any country and is not intended to convey conclusions about their efficacy or safety. There is no guarantee that PGN-EDODM1, PGN-EDO51 or any other investigational therapy will successfully complete clinical development or gain regulatory authority approval. View source version on businesswire.com: https://www.businesswire.com/news/home/20250508029516/en/ Contacts Investor Contact Laurence Watts New Street Investor Relations [email protected] Media Contact Julia Deutsch Lyra Strategic Advisory, LLC [email protected]