Dyne Therapeutics, Inc.

Previous wording

Our product candidate DYNE-101 is being evaluated in the ACHIEVE trial, a global Phase 1/2 clinical trial consisting of a 24-week multiple ascending dose, or MAD, randomized, placebo-controlled period, a 24-week open-label extension, or OLE, a 96-week long-term extension, and a registrational expansion cohort. The primary endpoints of the MAD portion of the trial were safety and tolerability; with secondary endpoints of pharmacokinetics and pharmacodynamics, including change from baseline in splicing as measured by the composite alternative splicing index, or CASI-22, video hand opening time, or vHOT, as well as multiple other measures of muscle strength and function and patient-reported outcomes, including the Myotonic Dystrophy Health Index. In the MAD portion of the ACHIEVE trial, patients were randomized to receive DYNE-101 or placebo intravenously every four weeks or every eight weeks for 24 weeks, depending on cohort. Patient cohorts were dosed from 1.8 mg/kg to 6.8 mg/kg (approximate ASO dose). Following the MAD placebo-controlled period, patients transition to DYNE-101 treatment in the OLE portion of the trial and in the long-term extension. In January 2025, we announced the completion of the MAD portion of the trial.

Current wording

Our product candidate zeleciment basivarsen, or z-basivarsen (also known as DYNE-101) is being evaluated in the ACHIEVE trial, a global Phase 1/2 clinical trial consisting of a 24-week multiple ascending dose, or MAD, randomized, placebo-controlled period, a 24-week open-label extension, or OLE, a 96-week long-term extension, and a registrational expansion cohort. The primary endpoints of the MAD portion of the trial were safety and tolerability; with secondary endpoints of pharmacokinetics and pharmacodynamics, including change from baseline in splicing as measured by the composite alternative splicing index, or CASI-22, video hand opening time, or vHOT, as well as multiple other measures of muscle strength and function and patient-reported outcomes, including the Myotonic Dystrophy Health Index. In the MAD portion of the ACHIEVE trial, patients were randomized to receive z-basivarsen or placebo intravenously every four weeks or every eight weeks for 24 weeks, depending on cohort. Patient cohorts were dosed from 1.8 mg/kg to 6.8 mg/kg (approximate ASO dose). Following the MAD placebo-controlled period, patients transition to z-basivarsen treatment in the OLE portion of the trial and in the long-term extension. In January 2025, we announced the completion of the MAD portion of the trial.

Previous wording

We participated in a Type C meeting with the U.S. Food and Drug Administration, or FDA, in May 2025 and discussed the path to regulatory approval, including U.S. Accelerated Approval, for DYNE-101 in DM1. As a result of the meeting, we submitted a revised protocol for review by the FDA in June 2025 for the registrational expansion cohort of the ACHIEVE trial. The primary endpoint in the revised protocol for the registrational expansion cohort is change from baseline in middle finger myotonia as measured by vHOT at 6 months compared to placebo, which is intended to serve as an intermediate clinical endpoint for U.S. Accelerated Approval. Secondary endpoints include change from baseline in splicing as measured by CASI-22, muscle strength as assessed by Quantitative Muscle Testing, or QMT, performance on both the 10-Meter Walk/Run Test, or 10MWR, and 5 Times Sit to Stand Test, or 5xSTS, and the Myotonic Dystrophy Health Index, or MDHI, patient reported outcome measure, all at 6 months compared to placebo. We intend that the data from the registrational expansion cohort and the already enrolled patients in the MAD and ongoing long-term extension portions of the ACHIEVE trial will support a potential submission for U.S. Accelerated Approval.

Current wording

We participated in a Type C meeting with the U.S. Food and Drug Administration, or FDA, in May 2025 and discussed the path to regulatory approval, including U.S. Accelerated Approval, for z-basivarsen in DM1. As a result of the meeting, we submitted a revised protocol for review by the FDA in June 2025 for the registrational expansion cohort of the ACHIEVE trial. The primary endpoint in the revised protocol for the registrational expansion cohort is change from baseline in middle finger myotonia as measured by vHOT at 6 months compared to placebo, which is intended to serve as an intermediate clinical endpoint for U.S. Accelerated Approval. Secondary endpoints include change from baseline in splicing as measured by CASI-22, muscle strength as assessed by Quantitative Muscle Testing, or QMT, performance on both the 10-Meter Walk/Run Test, or 10MWR, and 5 Times Sit to Stand Test, or 5xSTS, and the Myotonic Dystrophy Health Index, or MDHI, patient reported outcome measure, all at 6 months compared to placebo. We intend that the data from the registrational expansion cohort and the already enrolled patients in the MAD and ongoing long-term extension portions of the ACHIEVE trial will support a potential submission for U.S. Accelerated Approval.

Previous wording

The registrational expansion cohort is expected to enroll 60 patients at the 6.8 mg/kg once every eight weeks, or Q8W, dose cohort. The registrational expansion cohort has been initiated and full enrollment is planned for the fourth quarter of 2025, with data from this cohort planned for mid-2026 and potential submission for U.S. Accelerated Approval planned for late 2026. We continue to advance preparations for a Phase 3 clinical trial of DYNE-101 and plan to initiate the trial in the first quarter of 2026. We continue to pursue approval pathways for DYNE-101 outside of the U.S.

Current wording

The registrational expansion cohort is expected to enroll 60 patients at the 6.8 mg/kg once every eight weeks, or Q8W, dose cohort. The registrational expansion cohort has been initiated and full enrollment is planned for early in the second quarter of 2026, with data from this cohort planned for the first quarter of 2027 and potential submission for U.S.

Previous wording

In June 2025, the FDA granted Breakthrough Therapy Designation to DYNE-101 for the treatment of DM1.

Current wording

In June 2025, the FDA granted Breakthrough Therapy Designation to z-basivarsen for the treatment of DM1.

Previous wording

Additionally, in June 2025, we reported positive long-term efficacy and safety data from adult DM1 patients enrolled in the MAD portion of the ACHIEVE trial, including data from the 6.8 mg/kg Q8W cohort (n=6) at up to 12 months. At the 6.8 mg/kg Q8W dose, DYNE-101 demonstrated robust and sustained improvement in myotonia as measured by vHOT as well as sustained improvements across multiple other endpoints. We believe these data support improvement in vHOT as an early indicator of clinical benefit with DYNE-101 in DM1 and its potential as an intermediate clinical endpoint for U.S. Accelerated Approval. Treatment with DYNE-101 led to an improvement in vHOT of 3.3 seconds as compared to placebo at 6 months, and new data demonstrated that mean improvements at 6 months were sustained at 12 months for vHOT, 10MWR, 5xSTS, MDHI, and QMT, which demonstrated a 10% improvement in strength at 6 months, increasing to 20% at 12 months relative to baseline.

Current wording

Additionally, in June 2025, we reported positive long-term efficacy and safety data from adult DM1 patients enrolled in the MAD portion of the ACHIEVE trial, including data from the 6.8 mg/kg Q8W cohort (n=6) at up to 12 months. At the 6.8 mg/kg Q8W dose, z-basivarsen demonstrated robust and sustained improvement in myotonia as measured by vHOT as well as sustained improvements across multiple other endpoints. We believe these data support improvement in vHOT as an early indicator of clinical benefit with z-basivarsen in DM1 and its potential as an intermediate clinical endpoint for U.S. Accelerated Approval. Treatment with z-basivarsen led to an improvement in vHOT of 3.3 seconds as compared to placebo at 6 months, and new data demonstrated that mean improvements at 6 months were sustained at 12 months for vHOT, 10MWR, 5xSTS, MDHI, and QMT, which demonstrated a 10% improvement in strength at 6 months, increasing to 20% at 12 months relative to baseline. In October 2025, we reported additional analyses from the same 6.8 mg/kg Q8W cohort (n=6) data at 12 months. This included new data showing improvement from baseline in the 9-Hole Peg Test, or 9HPT, a measure of upper limb function focused on manual dexterity and coordination; QMT scores across both upper and lower extremities showing robust and sustained improvement; additional MDHI subscales of mobility, ability to do activities and upper extremity function showing robust and sustained improvement and the Patient Global Impression of Change, or PGI-C, and Clinician Global Impression of Change, or CGI-C, scales showing improvement in overall disease burden.

Previous wording

In June 2025, we also reported updated safety and tolerability data from the 56 patients enrolled through the 6.8 mg/kg Q8W cohort of the ACHIEVE trial. As of the data cutoff date of April 23, 2025, DYNE-101 demonstrated a favorable safety profile. Additionally, the majority of treatment-emergent adverse events were mild or moderate, and no related serious treatment-emergent adverse events were identified. In addition, no participants demonstrated persistent related anemia, and no clinically meaningful changes were observed in kidney or liver parameters. Also, no participants demonstrated kidney injury. Liver enzyme elevations were observed in a minority of participants, with no impact on liver function. Interpretation of the elevated liver enzyme levels was complicated by underlying liver disease and elevated baseline values up to approximately 2.5 times greater than the upper limit of normal.

Current wording

In June 2025, we also reported updated safety and tolerability data from the 56 patients enrolled through the 6.8 mg/kg Q8W cohort of the ACHIEVE trial. As of the data cutoff date of April 23, 2025, z-basivarsen demonstrated a favorable safety profile. Additionally, the majority of treatment-emergent adverse events were mild or moderate, and no related serious treatment-emergent adverse events were identified. In addition, no participants demonstrated persistent related anemia, and no clinically meaningful changes were observed in kidney or liver parameters. Also, no participants demonstrated kidney injury. Liver enzyme elevations were observed in a minority of participants, with no impact on liver function. Interpretation of the elevated liver enzyme levels was complicated by underlying liver disease and elevated baseline values up to approximately 2.5 times greater than the upper limit of normal.

Previous wording

Our product candidate DYNE-251 is currently being evaluated in the DELIVER trial, a Phase 1/2 global clinical trial consisting of a 24-week MAD randomized, placebo-controlled period, a 24-week OLE, and a 192-week long-term extension, and a registrational expansion cohort. The trial, which is designed to be registrational, enrolled ambulant and non-ambulant males with DMD who are ages 4 to 16 and have mutations amenable to exon 51 skipping. The primary endpoints of the MAD portion were safety, tolerability and change from baseline in dystrophin levels as measured by Western blot. Additional endpoints in the MAD portion of the trial included pharmacokinetics and change from baseline in exon 51 skipping levels, muscle tissue percent dystrophin positive fibers, multiple assessments of muscle function, including North Star Ambulatory Assessment score, Stride Velocity 95th Centile and certain timed functional tests.

Current wording

Our product candidate zeleciment rostudirsen, or z-rostudirsen (also known as DYNE-251) is currently being evaluated in the DELIVER trial, a Phase 1/2 global clinical trial consisting of a 24-week MAD randomized, placebo-controlled period, a 24-week OLE, and a 192-week long-term extension, and a registrational expansion cohort. The trial, which is designed to be registrational, enrolled ambulant and non-ambulant males with DMD who are ages 4 to 16 and have mutations amenable to exon 51 skipping. The primary endpoints of the MAD portion were safety, tolerability and change from baseline in dystrophin levels as measured by Western blot. Additional endpoints in the MAD portion of the trial included pharmacokinetics and change from baseline in exon 51 skipping levels, muscle tissue percent dystrophin positive fibers, multiple assessments of muscle function, including North Star Ambulatory Assessment score, Stride Velocity 95th Centile and certain timed functional tests.

Previous wording

In the MAD portion of the DELIVER trial, patients were randomized to receive DYNE-251 or placebo every four or eight weeks intravenously for 24 weeks, depending on cohort. Patients cohorts were dosed from 0.7 mg/kg to 20 mg/kg (approximate phosphorodiamidate morpholino oligomer, or PMO dose). Following the placebo-controlled period, patients transitioned to DYNE-251 treatment in the open-label portion of the trial and in the long-term extension.

Current wording

In the MAD portion of the DELIVER trial, patients were randomized to receive z-rostudirsen or placebo every four or eight weeks intravenously for 24 weeks, depending on cohort. Patients cohorts were dosed from 0.7 mg/kg to 20 mg/kg (approximate phosphorodiamidate morpholino oligomer, or PMO dose). Following the placebo-controlled period, patients transitioned to z-rostudirsen treatment in the open-label portion of the trial and in the long-term extension.

Previous wording

In March 2025, we reported positive long-term safety and efficacy data from the MAD portion of the DELIVER trial. The efficacy assessment of the DELIVER trial reported in March 2025 was based on 12-month biomarker and functional data from six male patients enrolled in the 20 mg/kg (approximate PMO dose) cohort who were randomized to receive DYNE-251 or placebo once every four weeks, or Q4W, and 18-month functional data from six male patients in the 10 mg/kg (approximate PMO dose) cohort who were randomized to receive DYNE-251 or placebo Q4W. During the open label extension period, all participants in the 10 mg/kg cohort were dose escalated to 20 mg/kg Q4W regimen after month six. DYNE-251 demonstrated dose-dependent exon skipping and dystrophin expression and meaningful and sustained improvements from baseline in multiple functional endpoints in both cohorts. In the 20 mg/kg Q4W cohort, DYNE-251 demonstrated best-in-class levels of dystrophin expression, exon skipping and percent dystrophin.

Current wording

In March 2025, we reported positive long-term safety and efficacy data from the MAD portion of the DELIVER trial. The efficacy assessment of the DELIVER trial reported in March 2025 was based on 12-month biomarker and functional data from six male patients enrolled in the 20 mg/kg (approximate PMO dose) cohort who were randomized to receive z-rostudirsen or placebo once every four weeks, or Q4W, and 18-month functional data from six male patients in the 10 mg/kg (approximate PMO dose) cohort who were randomized to receive z-rostudirsen or placebo Q4W. During the open label extension period, all participants in the 10 mg/kg cohort were dose escalated to 20 mg/kg Q4W regimen after month six. Z-rostudirsen demonstrated dose-dependent exon skipping and dystrophin expression and meaningful and sustained improvements from baseline in multiple functional endpoints in both cohorts. In the 20 mg/kg Q4W cohort, z-rostudirsen demonstrated best-in-class levels of dystrophin expression, exon skipping and percent dystrophin.

Previous wording

In March 2025, we also reported updated safety and tolerability data based on 54 participants enrolled in the DELIVER trial. As of the data cutoff date of February 7, 2025, DYNE-251 demonstrated a favorable safety profile and the majority of treatment emergent adverse events were mild or moderate and no related serious treatment emergent adverse events were identified other than in two participants at the 40 mg/kg Q4W dose level which events were potentially related to study drug. One participant experienced symptoms which suggested hemolytic uremic syndrome, potentially caused by an infection. The second participant had a history of unexplained hemolytic anemia and developed fever and tonsillitis after joining the DELIVER trial. Both participants have recovered.

Current wording

In March 2025, we also reported updated safety and tolerability data based on 54 participants enrolled in the DELIVER trial. As of the data cutoff date of February 7, 2025, z-rostudirsen demonstrated a favorable safety profile and the majority of treatment emergent adverse events were mild or moderate and no related serious treatment emergent adverse events were identified other than in two participants at the 40 mg/kg Q4W dose level which events were potentially related to study drug. One participant experienced symptoms which suggested hemolytic uremic syndrome, potentially caused by an infection. The second participant had a history of unexplained hemolytic anemia and developed fever and tonsillitis after joining the DELIVER trial. Both participants have recovered.

Previous wording

We completed enrollment of the 20 mg/kg Q4W (approximate PMO dose) registrational expansion cohort of 32 participants as part of the DELIVER trial in the first quarter of 2025 and are planning for data from this cohort in late 2025 and potential submission for U.S. Accelerated Approval in early 2026. We continue to pursue accelerated approval in the U.S. based on dystrophin as a surrogate endpoint. We continue to pursue approval pathways for DYNE-251 outside of the U.S.

Current wording

We completed enrollment of the 20 mg/kg Q4W (approximate PMO dose) registrational expansion cohort of 32 participants as part of the DELIVER trial in March 2025 and are planning for data from this cohort in December 2025 and potential submission for U.S. Accelerated Approval in the second quarter of 2026. We continue to pursue accelerated approval in the U.S. based on dystrophin as a surrogate endpoint. We continue to pursue approval pathways for z-rostudirsen outside of the U.S.

Previous wording

Since our inception, we have incurred significant operating losses. Our ability to generate any product revenue or product revenue sufficient to achieve profitability will depend on the successful development and eventual commercialization of one or more product candidates. For the six months ended June 30, 2025 and 2024, we reported net losses of $226.2 million and $130.8 million, respectively. As of June 30, 2025, we had an accumulated deficit of $1.2 billion.

Current wording

Since our inception, we have incurred significant operating losses. Our ability to generate any product revenue or product revenue sufficient to achieve profitability will depend on the successful development and eventual commercialization of one or more product candidates. For the nine months ended September 30, 2025 and 2024, we reported net losses of $334.3 million and $227.9 million, respectively. As of September 30, 2025, we had an accumulated deficit of $1.3 billion.

Previous wording

We believe that our existing cash, cash equivalents and marketable securities, which includes the initial term loan tranche of $100.0 million that we borrowed under our Loan Agreement with Hercules in June 2025, as well as the net proceeds from our follow-on public offering completed in July 2025, which we refer to as the July 2025 offering, will enable us to fund our operating expenses, debt service obligations and capital expenditure requirements into the third quarter of 2027. Based on our current plans and anticipated timelines and assuming positive data results from the Registrational Expansion Cohorts of our ACHIEVE and DELIVER clinical trials and assuming no additional testing is required by the FDA, we estimate that these cash resources would be sufficient to enable us to obtain data from the Registrational Expansion Cohorts of our ACHIEVE and DELIVER clinical trials, submit applications for marketing approval to the FDA for DYNE-251 in DMD and DYNE-101 in DM1 using the Accelerated Approval pathway and obtain a decision from the FDA with respect to the application for marketing approval for DYNE-251 and, if approved, commercially launch DYNE-251 in the United States.

Current wording

We believe that our existing cash, cash equivalents and marketable securities will enable us to fund our operating expenses, debt service obligations and capital expenditure requirements into the third quarter of 2027. Based on our current plans and anticipated timelines and assuming positive data results from the Registrational Expansion Cohorts of our ACHIEVE and DELIVER clinical trials and assuming no additional testing is required by the FDA, we estimate that these cash resources would be sufficient to enable us to obtain data from the Registrational Expansion Cohorts of our ACHIEVE and DELIVER clinical trials, submit applications for marketing approval to the FDA for z-rostudirsen in DMD and z-basivarsen in DM1 using the Accelerated Approval pathway and obtain a decision from the FDA with respect to the application for marketing approval for z-rostudirsen and, if approved, commercially launch z-rostudirsen in the United States.

Previous wording

the cost of laboratory supplies and acquiring, developing and manufacturing materials for use in our research, preclinical studies and clinical trials, including those incurred under agreements with third parties, such as consultants and contract manufacturing organizations, or CMOs;

Current wording

the cost of laboratory supplies and acquiring, developing and manufacturing materials for use in our research, preclinical studies and clinical trials, including those incurred under agreements with third parties, such as consultants and CMOs;

Previous wording

Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. Accordingly, we expect that our research and development expenses will increase substantially as we advance DYNE-101 and DYNE-251 through clinical trials, in connection with our preclinical and clinical development activities of DYNE-302, our FSHD product candidate, and DYNE-401, our Pompe disease product candidate, and if, and as, we advance any other product candidates through preclinical studies and clinical trials. At this time, we cannot accurately estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any product candidates we may develop. The successful development of any product candidate is highly uncertain. This is due to the numerous risks and uncertainties associated with product development, including the following:

Current wording

Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. Accordingly, we expect that our research and development expenses will increase substantially as we advance z-basivarsen and z-rostudirsen through clinical trials, in connection with our preclinical and clinical development activities of DYNE-302, our FSHD product candidate, and DYNE-401, our Pompe disease product candidate, and if, and as, we advance any other product candidates through preclinical studies and clinical trials. At this time, we cannot accurately estimate or know the nature, timing and costs of the efforts that will be necessary to complete the preclinical and clinical development of any product candidates we may develop. The successful development of any product candidate is highly uncertain. This is due to the numerous risks and uncertainties associated with product development, including the following:

Previous wording

Expenses related to DYNE-101 increased in the six months ended June 30, 2025 compared to the six months ended June 30, 2024. This was attributable to higher manufacturing activity in the six months ended June 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing ACHIEVE trial and an increase in clinical trial activity for the registrational expansion cohort of the ACHIEVE trial. Expenses related to DYNE-251 increased in the six months ended June 30, 2025 compared to the six months ended June 30, 2024. This was attributable to higher manufacturing activity in the six months ended June 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing DELIVER trial and an increase in clinical trial activity for the registrational expansion cohort of the DELIVER trial.

Current wording

Expenses related to z-basivarsen increased in the three months ended September 30, 2025 compared to the three months ended September 30, 2024. This was attributable to higher manufacturing activity in the three months ended September 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing ACHIEVE trial and an increase in clinical trial activity primarily for the registrational expansion cohort of the ACHIEVE trial. Expenses related to z-rostudirsen decreased in the three months ended September 30, 2025 compared to the three months ended September 30, 2024. This was attributable to lower manufacturing cost in the three months ended September 30, 2025 due to the timing of a new raw material purchase in the three months ended September 30, 2024.

Previous wording

The increase in platform and external research and development expenses in the six months ended June 30, 2025 compared to the six months ended June 30, 2024 was primarily due to increased external research activity associated with our preclinical programs and product candidates. The increase in personnel-related expenses was primarily due to increased headcount in our research and development function. The increase in facility-related and other expenses was primarily due to the increased costs of supporting a larger number of research and development personnel.

Current wording

The decrease in platform and external research and development expenses in the three months ended September 30, 2025 compared to the three months ended September 30, 2024 was primarily due to timing of raw material purchases in manufacturing. The increase in personnel-related expenses was primarily due to increased headcount in our research and development function. The increase in facility-related and other expenses was primarily due to the increased costs of supporting a larger number of research and development personnel.

Previous wording

Interest income for the three months ended June 30, 2025 and 2024 was $6.6 million and $7.1 million, respectively, due to interest earned on invested cash balances. The decrease in interest income was due to an overall decrease in interest rates in the three months ended June 30, 2025 compared to the three months ended June 30, 2024.

Current wording

Interest income for the three months ended September 30, 2025 and 2024 was $8.5 million and $9.3 million, respectively, due to interest earned on invested cash balances. The decrease in interest income was due to an overall decrease in interest rates in the three months ended September 30, 2025 compared to the three months ended September 30, 2024.

Previous wording

Interest expense for the three months ended June 30, 2025 was $0.1 million due to our entry into the Loan Agreement with Hercules in June 2025. No interest expense was incurred in the three months ended June 30, 2024.

Current wording

Interest expense for the three months ended September 30, 2025 was $2.9 million due to our entry into the Loan Agreement with Hercules in June 2025. No interest expense was incurred in the three months ended September 30, 2024.

Previous wording

Other expense for the three months ended June 30, 2025 and 2024 was $1.6 million and $0.2 million, respectively, due to realized foreign currency losses.

Current wording

Other income for the three months ended September 30, 2025 was $0.3 million while other expense for the three months ended September 30, 2024 was $0.7 million due to realized foreign currency gains.

Previous wording

The following table summarizes our results of operations for the six months ended June 30, 2025 and 2024:

Current wording

The following table summarizes our results of operations for the nine months ended September 30, 2025 and 2024:

Previous wording

The following table summarizes our research and development expenses for the six months ended June 30, 2025 and 2024:

Current wording

The following table summarizes our research and development expenses for the nine months ended September 30, 2025 and 2024:

Previous wording

Expenses related to DYNE-101 increased in the three months ended June 30, 2025 compared to the three months ended June 30, 2024. This was attributable to higher manufacturing activity in the three months ended June 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing ACHIEVE trial and an increase in clinical trial activity for the registrational expansion cohort of the ACHIEVE trial. Expenses related to DYNE-251 increased in the three months ended June 30, 2025 compared to the three months ended June 30, 2024. This was attributable to higher manufacturing activity in the three months ended June 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing DELIVER trial and an increase in clinical trial activity for the registrational expansion cohort of the DELIVER trial.

Current wording

Expenses related to z-basivarsen increased in the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024. This was attributable to higher manufacturing activity in the nine months ended September 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing ACHIEVE trial and an increase in clinical trial activity for the registrational expansion cohort of the ACHIEVE trial. Expenses related to z-rostudirsen increased in the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024. This was attributable to higher manufacturing activity in the nine months ended September 30, 2025 to produce a sufficient clinical supply of drug product for the ongoing DELIVER trial and an increase in clinical trial activity for the registrational expansion cohort of the DELIVER trial.

Previous wording

The increase in platform and external research and development expenses in the three months ended June 30, 2025 compared to the three months ended June 30, 2024 was primarily due to increased external research activity associated with our preclinical programs and product candidates. The increase in personnel-related expenses was primarily due to increased headcount in our research and development function. The increase in facility-related and other expenses was primarily due to the increased costs of supporting a larger number of research and development personnel.

Current wording

The increase in platform and external research and development expenses in the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 was primarily due to increased external research activity associated with our preclinical programs and product candidates. The increase in personnel-related expenses was primarily due to increased headcount in our research and development function. The increase in facility-related and other expenses was primarily due to the increased costs of supporting a larger number of research and development personnel.

Previous wording

The following table summarizes our general and administrative expenses for the six months ended June 30, 2025 and 2024:

Current wording

The following table summarizes our general and administrative expenses for the nine months ended September 30, 2025 and 2024:

Previous wording

The increase in personnel-related expenses in the six months ended June 30, 2025 compared to the six months ended June 30, 2024 was due to increased headcount in our general and administrative function. The decrease in stock-based compensation expense in the six months ended June 30, 2025 compared to the six months ended June 30, 2024 was primarily the result of entering into separation and consulting agreements with our former chief executive officer in March 2024, resulting in the acceleration of vesting and modification of previously granted awards. Professional and consulting fees increased due to the higher consulting costs to support the growth of the organization in the six months ended June 30, 2025. Facility-related and other expenses increased due to higher costs of supporting a larger number of general and administrative personnel in the six months ended June 30, 2025.

Current wording

The increase in personnel-related expenses in the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 was due to increased headcount in our general and administrative function. The decrease in stock-based compensation expense in the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 was primarily the result of entering into separation and consulting agreements with our former chief executive officer in March 2024 and former chief business officer in September 2024, resulting in the acceleration of vesting and modification of previously granted awards. Professional and consulting fees increased due to the higher consulting costs to support the growth of the organization in the nine months ended September 30, 2025. Facility-related and other expenses increased due to higher costs of supporting a larger number of general and administrative personnel in the nine months ended September 30, 2025.

Previous wording

Interest income for the six months ended June 30, 2025 and 2024 was $13.7 million and $10.1 million, respectively, due to interest earned on invested cash balances. The increase in interest income was due to an increased cash, cash equivalents and marketable securities balance throughout the six months ended June 30, 2025 compared to the six months ended June 30, 2024.

Current wording

Interest income for the nine months ended September 30, 2025 and 2024 was $22.2 million and $19.3 million, respectively, due to interest earned on invested cash balances. The increase in interest income was due to an increased cash, cash equivalents and marketable securities balance throughout the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024.

Previous wording

Interest expense for the six months ended June 30, 2025 was $0.1 million due to our entry into the Loan Agreement with Hercules in June 2025. No interest expense was incurred in the six months ended June 30, 2024.

Current wording

Interest expense for the nine months ended September 30, 2025 was $3.0 million due to our entry into the Loan Agreement with Hercules in June 2025. No interest expense was incurred in the nine months ended September 30, 2024.

Previous wording

Other expense for the six months ended June 30, 2025 was $1.6 million due to net foreign currency losses. Other income for the six months ended June 30, 2024 was $0.3 million due to net foreign currency gains.

Current wording

Other expense for the nine months ended September 30, 2025 was $1.4 million due to net foreign currency losses. Other income for the nine months ended September 30, 2024 was $0.4 million due to net foreign currency gains.

Previous wording

Since our inception, we have incurred significant operating losses. We expect to incur significant expenses and operating losses for the foreseeable future as we support our continued research activities and development of our product candidates and platform. We have not yet commercialized any product candidates, and we do not expect to generate revenue from sales of any product candidates at least until 2027, if at all. To date, we have funded our operations primarily with proceeds from sales of equity securities and our initial borrowing under the Loan Agreement with Hercules. As of June 30, 2025 we had cash, cash equivalents and marketable securities of $683.9 million.

Current wording

Since our inception, we have incurred significant operating losses. We expect to incur significant expenses and operating losses for the foreseeable future as we support our continued research activities and development of our product candidates and platform. We have not yet commercialized any product candidates, and we do not expect to generate revenue from sales of any product candidates at least until 2027, if at all. To date, we have funded our operations primarily with proceeds from sales of equity securities and our initial borrowing under the Loan Agreement with Hercules. As of September 30, 2025 we had cash, cash equivalents and marketable securities of $791.9 million.

Previous wording

During the six months ended June 30, 2025, we issued and sold an aggregate of 10,660,159 shares of common stock pursuant to the Sales Agreement for aggregate net proceeds of $140.6 million, after deducting commissions and offering expenses payable by us. We sold such shares at a weighted average price of $13.60 per share.

Current wording

During the nine months ended September 30, 2025, we issued and sold an aggregate of 10,660,159 shares of common stock pursuant to the Sales Agreement for aggregate net proceeds of $140.6 million, after deducting commissions and offering expenses payable by us. We sold such shares at a weighted average price of $13.60 per share.

Previous wording

In July 2025, we completed the July 2025 offering, pursuant to which we issued and sold 27,878,788 shares of our common stock. We estimate that the net proceeds from the offering were approximately $215.2 million, after deducting underwriting discounts and commissions and offering expenses payable by us.

Current wording

In July 2025, we completed the July 2025 offering, pursuant to which we issued and sold 27,878,788 shares of our common stock. We received net proceeds from the offering of $215.8 million, after deducting underwriting discounts and commissions and offering expenses paid by us.

Previous wording

During the six months ended June 30, 2025, operating activities used $200.6 million of cash, due to our net loss of $226.2 million, partially offset by non-cash charges of $23.6 million and changes in our operating assets and liabilities of $2.0 million. Net cash provided by changes in our operating assets and liabilities primarily consisted of a $2.8 million decrease in prepaid expenses and other current assets, partially offset by a $0.8 million decrease in accounts payable and other liabilities. During the six months ended June 30, 2024, operating activities used $133.4 million of cash, due to our net loss of $130.8 million and net cash used by changes in our operating assets and liabilities of $28.6 million, partially offset by non-cash charges of $25.9 million. Net cash used by changes in our operating assets and liabilities primarily consisted of a $21.4 million decrease in accounts payable and other liabilities and a $7.2 million increase in prepaid expenses and other current assets. Changes in our operating assets and liabilities during these periods were generally due to the growth of our business, increased clinical trial activity, increased manufacturing activities, advancement of our product candidates, the timing of vendor invoices and payments and annual bonus payments.

Current wording

During the nine months ended September 30, 2025, operating activities used $291.4 million of cash, due to our net loss of $334.3 million, partially offset by non-cash charges of $35.0 million and changes in our operating assets and liabilities of $7.9 million. Net cash provided by changes in our operating assets and liabilities primarily consisted of a $17.7 million increase in accounts payable and other liabilities and a $3.2 million decrease in prepaid expenses and other current assets, partially offset by a $13.0 million increase in other non-current assets. During the nine months ended September 30, 2024, operating activities used $208.0 million of cash, due to our net loss of $227.9 million and net cash used by changes in our operating assets and liabilities of $14.4 million, partially offset by non-cash charges of $34.2 million. Net cash used by changes in our operating assets and liabilities primarily consisted of a $8.0 million decrease in accounts payable and other liabilities and a $6.4 million increase in prepaid expenses and other current assets. Changes in our operating assets and liabilities during these periods were generally due to the growth of our business, increased clinical trial activity, increased manufacturing activities, advancement of our product candidates, the timing of vendor invoices and payments and annual bonus payments.

Previous wording

During the six months ended June 30, 2025, net cash provided by investing activities was $8.2 million due to maturities of marketable securities of $107.7 million and sales of marketable securities of $8.5 million, partially offset by purchases of marketable securities of $106.9 and purchases of property and equipment of $1.0 million. During the six months ended June 30, 2024, net cash used in investing activities was $168.7 million due to purchases of marketable securities of $207.7 million and purchases of property and equipment of $1.0 million, partially offset by maturities of marketable securities of $40.1 million.

Current wording

During the nine months ended September 30, 2025, net cash used in investing activities was $29.7 million due to purchases of marketable securities of $153.8 million, an advance payment for long-lead equipment for $18.8 million, and purchases of property and equipment of $1.4 million, partially offset by maturities of marketable securities of $135.8 million and sales of marketable securities of $8.5 million. During the nine months ended September 30, 2024, net cash used in investing activities was $188.1 million due to purchases of marketable securities of $264.7 million and purchases of property and equipment of $1.3 million, partially offset by maturities of marketable securities of $76.2 million and sales of marketable securities of $1.7 million.

Previous wording

During the six months ended June 30, 2025, net cash provided by financing activities was $242.0 million, consisting of $140.6 million in aggregate net proceeds from sales of common stock under our at-the-market offering program, $98.8 million in net proceeds from the initial term loan tranche under the Loan Agreement with Hercules and $2.6 million in proceeds received from stock option exercises. During the six months ended June 30, 2024, net cash provided by financing activities was $788.3 million, consisting of $675.2 million in aggregate net proceeds from sales in our public offerings in January 2024 and May 2024, $97.9 million in aggregate net proceeds from sales of our common stock under our at-the-market offering program and $15.2 million in net proceeds received from stock option exercises.

Current wording

During the nine months ended September 30, 2025, net cash provided by financing activities was $459.3 million, consisting of $215.8 million in aggregate net proceeds from sales of common stock under our follow-on offering in July 2025, $140.6 million in aggregate net proceeds from sales of common stock under our at-the-market offering program, $98.8 million in net proceeds from the initial term loan tranche under the Loan Agreement with Hercules and $4.6 million in proceeds received from stock option exercises. These cash inflows are partially offset by $0.5 million in payment of debt issuance costs. During the nine months ended September 30, 2024, net cash provided by financing activities was $806.3 million, consisting of $675.2 million in aggregate net proceeds from sales in our public offerings in January 2024 and May 2024, $97.9 million in aggregate net proceeds from sales of our common stock under our at-the-market offering program and $33.2 million in net proceeds received from stock option exercises.

Previous wording

We expect our expenses to increase in connection with our ongoing activities, particularly as we advance the clinical development of DYNE-101 and DYNE-251, the development of our FSHD and Pompe programs and additional research programs. The timing and amount of our operating expenditures will depend largely on:

Current wording

We expect our expenses to increase in connection with our ongoing activities, particularly as we advance the clinical development of z-basivarsen and z-rostudirsen, the development of our FSHD and Pompe programs and additional research programs. The timing and amount of our operating expenditures will depend largely on:

Previous wording

We believe that our existing cash, cash equivalents and marketable securities, which includes the initial term loan tranche of $100.0 million that we borrowed under our Loan Agreement with Hercules in June 2025, as well as the net proceeds from the July 2025 offering, will enable us to fund our operating expenses, debt service obligations and capital expenditure requirements into the third quarter of 2027. Based on our current plans and anticipated timelines and assuming positive data results from the registrational expansion cohorts of our ACHIEVE and DELIVER clinical trials and assuming no additional testing is required by the FDA, we estimate that these cash resources would be sufficient to enable us to obtain data from the registrational expansion cohorts of our ACHIEVE and DELIVER clinical trials, submit applications for marketing approval to the FDA for DYNE-251 in DMD and DYNE-101 in DM1 using the Accelerated Approval pathway and obtain a decision from the FDA with respect to the application for marketing approval for DYNE-251 and, if approved, commercially launch DYNE-251 in the United States. We have based these estimates on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect.

Current wording

We believe that our existing cash, cash equivalents and marketable securities will enable us to fund our operating expenses, debt service obligations and capital expenditure requirements into the third quarter of 2027. Based on our current plans and anticipated timelines and assuming positive data results from the registrational expansion cohorts of our ACHIEVE and DELIVER clinical trials and assuming no additional testing is required by the FDA, we estimate that these cash resources would be sufficient to enable us to obtain data from the registrational expansion cohorts of our ACHIEVE and DELIVER clinical trials, submit applications for marketing approval to the FDA for z-rostudirsen in DMD and z-basivarsen in DM1 using the Accelerated Approval pathway and obtain a decision from the FDA with respect to the application for marketing approval for z-rostudirsen and, if approved, commercially launch z-rostudirsen in the United States. We have based these estimates on assumptions that may prove to be wrong, and we could exhaust our available capital resources sooner than we expect.

Previous wording

On January 15, 2025, we entered into a master manufacturing services agreement with a CMO which secures capacity at the CMO’s manufacturing facilities for certain of our product candidates and components thereof. The agreement obligates us to compensate the CMO at least $60 million for producing certain of our product candidates and components thereof through 2026. In specified termination circumstances, the agreement requires us to pay the CMO for services completed, the cost of the CMO’s raw materials that cannot be repurposed and specified cancellation fees. This agreement formalizes and supersedes a letter agreement that we entered into with the CMO on July 18, 2024.

Current wording

On January 15, 2025, we entered into a master manufacturing services agreement with a CMO which secures capacity at the CMO's manufacturing facilities for certain of our product candidates and components thereof. As of September 30, 2025, we have paid $31.2 million towards non-current assets under this agreement and pursuant to a mutually agreed rolling forecast we have committed to pay an additional $65.6 million in fees through September 2027. In specified termination circumstances, the agreement requires us to pay the CMO for services completed, the cost of the CMO's raw materials that cannot be repurposed and specified cancellation fees. This agreement formalizes and supersedes a letter agreement that we entered into with the CMO on July 18, 2024.