Duchenne Muscular DystrophyPhase 1NCT03362502

A Study to Evaluate the Safety and Tolerability of PF-06939926 Gene Therapy in Duchenne Muscular Dystrophy

A Phase 1 study testing PF-06939926 in people with Duchenne Muscular Dystrophy, run by Pfizer at 22 sites in United States.

Terminated

Stopped early. The study ended before it was planned to and will not resume.

Official record

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Trial summary

This is a first-in-human/first-in-patient, multi-center, open-label, non-randomized, ascending dose, safety and tolerability study of a single intravenous infusion of PF-06939926 in ambulatory and non-ambulatory subjects with Duchenne muscular dystrophy (DMD). Read more about this study

Who is it for?: Ages 4 years and older, men only
Conditions the study is for: Duchenne Muscular Dystrophy
What is being tested?: PF-06939926
Type of treatment: Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 23 participants
Where: 22 sitesUnited States
Study dates: 23 Jan 2018to 28 Jul 2025
Phase: Phase 1
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 4 years and older
Men only
No healthy volunteers
Child, Adult, Older adult

Who may be able to join

Age as follows, based on ambulatory status:
FOR AMBULATORY PARTICIPANTS, defined as the ability to walk at least 10 meters unassisted: Between 4 and 12 years, inclusive,
FOR NON-AMBULATORY PARTICIPANTS, defined as the inability to walk at least 10 meters unassisted: No age restrictions so long as loss of ambulation occurs prior to the subject's 17th birthday;
Diagnosis of Duchenne muscular dystrophy confirmed by medical history and genetic testing;
Receipt of glucocorticoids for 6 months and a stable daily dose for at least 3 months prior to study entry;
Ability to tolerate magnetic resonance imaging (MRI) without sedation and with no contraindications to these procedures;

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Ability to tolerate muscle biopsies under anesthesia with no contraindications to these procedures;
Body weights as follows, based on ambulatory status:
FOR AMBULATORY PARTICIPANTS: Between 15 kg and 50 kg,
FOR NON-AMBULATORY PARTICIPANTS: Less than 75 kg, but which may be managed or adjusted to a lower limit, especially to ensure participant safety;
Functional performance as follows, based on ambulatory status:
FOR AMBULATORY PARTICIPANTS: Ability to rise from floor within seven (7) seconds,
FOR NON-AMBULATORY PARTICIPANTS: Percent predicted forced vital capacity greater than 40% as part of pulmonary function tests, as well as adequate upper limb function.
> 8 years of age Exclusion Criteria
Hypersensitivity to sirolimus or intolerance to soy, including a history of angioedema
Concomitant use with strong CYP3A4/P-gp inducers or inhibitors

Who cannot join

Receipt of live attenuated vaccination within 3 months prior to receiving PF-06939926 or exposure to an influenza (or other inactivated) vaccination or systemic antiviral and/or interferon therapy within 30 days prior to receipt of PF-06939926;
Prior exposure to any gene therapy agent, including exon-skipping agents;
Exposure to other investigational drugs within 30 days or 5 half-lives, whichever is longer;
Neutralizing antibodies (NAb) against adeno-associated virus, serotype 9 (AAV9);
Compromised cardiac function as indicated by left ventricular ejection fraction on cardiac MRI, as follows, based on ambulatory status:
FOR AMBULATORY PARTICIPANTS: Less than 55%,

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FOR NON-AMBULATORY PARTICIPANTS: Less than 35%;
Inadequate hepatic or renal function or risk factors for autoimmune disease on screening laboratory assessments.
The following genetic abnormalities in the dystrophin gene as confirmed by the investigator based on the review of the DMD genetic testing:
Any mutation (exon deletion, exon duplication, insertion, or point mutation) affecting any exon between exon 9 and exon 13, inclusive; OR
A deletion that affects both exon 29 and exon 30.
Sirolimus Cohort

Trial locations and contacts

22 sites in 1 country.

City, postcode or hospital

22 sites in 1 country

United States22 sites

Duke Neurology
Durham, North Carolina, 27705
Duke University Medical Center, Lenox Baker Children's Hospital
Durham, North Carolina, 27705
Biospecimen Repository & Processing Core - BPRC
Durham, North Carolina, 27710
Duke Cardiovascular Magnetic Resonance Center
Durham, North Carolina, 27710
Duke Children's Hospital & Health Center
Durham, North Carolina, 27710
Duke University Hospital Investigational Drug Services (IDS) Pharmacy
Durham, North Carolina, 27710
MRI Research Center
Los Angeles, California, 90095
Reed Neurological Research Center
Los Angeles, California, 90095
Ronald Reagan UCLA Medical Center (Investigational Drug Section)
Los Angeles, California, 90095
Ronald Reagan UCLA Medical Center - Interventional Radiology
Los Angeles, California, 90095
Ronald Reagan UCLA Medical Center Drug Information Center
Los Angeles, California, 90095
UCLA (David Geffen School of Medicine)
Los Angeles, California, 90095
UCLA Children's Heart Center
Los Angeles, California, 90095
UCLA Mattel Children's Hospital
Los Angeles, California, 90095
UCLA Medical Center
Los Angeles, California, 90095
UCLA Outpatient Surgery Center
Los Angeles, California, 90095
CCTS Clinical Research Center
Salt Lake City, Utah, 84108
University of Utah Imaging and Neurosciences Center
Salt Lake City, Utah, 84108
University of Utah Hospital & Clinics Investigational Drug Services
Salt Lake City, Utah, 84112
University of Utah Hospital
Salt Lake City, Utah, 84112
Primary Children's Hospital
Salt Lake City, Utah, 84113
University of Utah Clinical Neurosciences Center
Salt Lake City, Utah, 84132

Other trials in United States

About this study

Official title: A PHASE 1B MULTICENTER, OPEN-LABEL, SINGLE ASCENDING DOSE STUDY TO EVALUATE THE SAFETY AND TOLERABILITY OF PF-06939926 IN AMBULATORY AND NON-AMBULATORY SUBJECTS WITH DUCHENNE MUSCULAR DYSTROPHY

A total of approximately 22 subjects will receive PF-06939926, and these will include both ambulatory and non-ambulatory subjects. Up to 13 subjects may be included in a cohort that includes the concomitant medication, sirolimus. In order to mitigate unanticipated risks to subject safety, enrollment will be staggered within and between two planned dose-levels and will include a formal review by an external data monitoring committee (E-DMC) prior to dose progression.

Conditions: Duchenne Muscular Dystrophy
Being tested: PF-06939926
Keywords: gene therapy, mini-dystrophin, AAV, fordadistrogene movaparvovec
Medical subject headings: Muscular Dystrophy, Duchenne

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

PF-06939926Genetic
Recombinant adeno-associated virus, serotype 9 (AAV9) carrying a truncated human dystrophin gene (mini-dystrophin) under the control of a muscle-specific promoter.
Subjects will receive a single intravenous infusion of one of 2 dose levels.

Study groups in NCT03362502
Study group	Role	What they receive
PF-06939926	Experimental	Not described Receives: Genetic: PF-06939926

What is being measured

The primary outcome is the main question the study is designed to answer.

Number of Participants With All-Causality Treatment-Emergent Adverse Events (TEAEs) for 1-Year Follow-Up
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a treatment-emergent AE (TEAE). A serious AE (SAE) was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. Severe AE=an event that prevents normal everyday activities.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With All-Causality TEAEs by System Organ Class (SOC) and Preferred Term (PT) for 1-Year Follow-Up
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. For this outcome measure, TEAEs were reported according to Medical Dictionary for Regulatory Activities (MedDRA) version 25.0 SOC and PT.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Treatment-Related TEAEs for 1-Year Follow-Up
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. An SAE was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. Severe AE=an event that prevents normal everyday activities. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Treatment-related AEs and SAEs were determined by the investigator.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Treatment-Related TEAEs by SOC and PT for 1-Year Follow-Up
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. For this outcome measure, TEAEs were reported according to MedDRA version 25.0 SOC and PT. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Treatment-related AEs were determined by the investigator.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With All-Causality SAEs by SOC and PT for 1-Year Follow-Up
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. An SAE was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. For this outcome measure, TEAEs were reported according to MedDRA version 25.0 SOC and PT.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Treatment-Related SAEs by SOC and PT for 1-Year Follow-Up
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. An SAE was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Treatment-related AEs and SAEs were determined by the investigator. For this outcome measure, TEAEs were reported according to MedDRA version 25.0 SOC and PT.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Laboratory Test Abnormalities Without Regard to Baseline Abnormality for 1-Year Follow-Up - Hematology
Following hematologic parameters were analyzed for laboratory examination: hemoglobin, hematocrit, red blood cell (RBC) count, platelet count, white blood cell count, total neutrophils, absolute neutrophils (ANC), eosinophils, monocytes, basophils, lymphocytes, red blood cell indices, and haptoglobin. Laboratory abnormalities with occurrence in at least 1 participant are reported for this outcome measure. Baseline was defined as the last pre-dose measurement.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Laboratory Test Abnormalities Without Regard to Baseline Abnormality for 1-Year Follow-Up - Clinical Chemistry
Following parameters for clinical chemistry were analyzed for laboratory examination: blood urea nitrogen (BUN) and creatinine, glucose, calcium, sodium, potassium, chloride, total CO2 (bicarbonate), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (direct and indirect bilirubin), alkaline phosphatase, uric acid, albumin, total protein, serum phosphorus, cystatin C, creatine kinase, creatine kinase myocardial b fraction (CK-MB), amylase, lipase, gamma-glutamyl transferase (GGT), C-reactive protein (CRP), and cardiac troponin I. Laboratory abnormalities with occurrence in at least 1 participant are reported for this outcome measure. Baseline was defined as the last pre-dose measurement.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Laboratory Test Abnormalities Without Regard to Baseline Abnormality for 1-Year Follow-Up - Urinalysis
Following parameters for urinalysis were analyzed for laboratory examination: pH, glucose, protein, blood, ketones, nitrites, leukocyte esterase, and microscopy. Laboratory abnormalities with occurrence in at least 1 participant are reported for this outcome measure. Baseline was defined as the last pre-dose measurement.
Measured: Baseline up to 1 year post dose of PF-06939926
Change From Baseline on Left Ventricular Ejection Fraction as Measured by Cardiac Magnetic Resonance Imaging (MRI) for 1-Year Follow-Up
Cardiac MRI was performed after thigh and upper limb MRI or on separate days within the required visit window. Change in LVEF is presented as percentages, and was calculated as [(stroke volume) / (end-diastolic volume)]*100%. Baseline is defined as the last pre-dose measurement. Change from baseline on Day 360 (ie, 1 year post dose) was reported for this outcome measure.
Measured: Baseline, 1 year post dose of PF-06839926 (Day 360)
Number of Participants With Electrocardiograms (ECGs) Meeting the Pre-Defined Categorical Criteria for 1-Year Follow-Up
Triplicate ECG was performed after the participant had rested quietly for at least 10 minutes in a supine position. The pre-defined categorical criteria include PR interval aggregate (msec): value>=300, baseline>200 and percent change>=25%, baseline<=200 and percent change>=50%; QRS duration aggregate (msec): value>=140, percent change>=50%; QTcF interval aggregate (msec): 450<=value<480, 480<=value<500, value>=500, 30<=change<60, change>=60. Only the category(ies) with at least 1 participant meeting the pre-defined criterion is/are reported for this outcome measure. Baseline for ECG was defined as the measurement before the Day 1 study drug administration.
Measured: Baseline up to 1 year post dose of PF-06939926
Number of Participants With Positive Responses on Columbia-Suicide Severity Rating Scale (C-SSRS) According to the Columbia Classification Algorithm of Suicide Assessment (C-CASA) Categories
C-SSRS is a participant rated questionnaire to assess whether participant experienced the following: completed suicide(1), suicide attempt(2)("Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior(3)("Yes" on "preparatory acts or behavior"), suicidal ideation(4)("Yes" on "wish to be dead","non-specific active suicidal thoughts","active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent), any suicidal behavior or ideation, self-injurious behavior(7)("Yes" on "Has subject engaged in non-suicidal self-injurious behavior"). Yes/No responses are mapped to C-CASA categories. C-SSRS was conducted with the participant's care giver/legal guardian on the participant's behalf throughout the study for participants<=12 years of age at screening. Baseline is defined as the last predose measurement. Number of participants with responses of "Yes" is reported for this outcome measure.
Measured: Baseline, Day 7, Day 14, Day 180, and Day 360
Number of Participants With Vital Signs Meeting the Pre-Defined Categorical Criteria for 1-Year Follow-Up
Vital signs consisted of blood pressure, respiratory rate, and heart rate, was obtained with these measurements at the following timepoints: within 30 minutes before and approximately 30 minutes, 1, 2, 4, 8, and 24 hours after the start of the infusion, and on Days 4, 7, 10, 14, 30, 90, 180, and 360. Baseline was defined as the last pre-dose recording. Number of participants who had at least 1 vital sign measurement at the specified timepoints meeting the pre-defined criteria from baseline up to the end of 1-year follow-up is reported for this outcome measure.
Measured: Baseline up to 1 year post dose of PF-06939926

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

23 Jan 201828 Jul 2025

First posted5 Dec 2017
Study start23 Jan 2018
Primary completion28 Mar 2022
Study completion28 Jul 2025

Why it stopped: All participants who have received fordadistrogene movaparvovec in any Pfizer study will now be assessed for long-term safety in 1 combined study: C3391003

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (4)Papers the sponsor has linked to this study.
Other trials for Duchenne Muscular DystrophyStudies of the same condition, open and under way.
More trials run by PfizerThe sponsor's other registered studies.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 1
Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Sequential
Masking: None (open label)
Enrolment: 23 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT03362502
Sponsor's protocol ID: C3391001
Other IDs: NCT03362502
Status last verified: Aug 2025
First submitted: 29 Nov 2017
Last updated: 15 Sep 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Publications

Walsh J, Palandra J, Duriga N, Beidler D, McIntosh A, Binks M, Neubert H. Dystrophin/mini-dystrophin expression analysis by immunoaffinity liquid chromatography-tandem mass spectrometry after gene therapy for DMD. Gene Ther. 2025 Dec;32(6):573-580. doi: 10.1038/s41434-025-00554-5. Epub 2025 Aug 2.
PubMed 40753271
Byrne BJ, Butterfield RJ, Shieh PB, Smith EC, Licht C, Binks M, Casinghino S, Delnomdedieu M, Ravindra KC, McDonnell T, Ryan K, Schulz M, Shen Q, Shi H, Sirivelu MP, Vaidya VS, Whiteley L, Levy DI. Complement activation in a phase Ib study of fordadistrogene movaparvovec for Duchenne muscular dystrophy. Mol Ther. 2025 Sep 3;33(9):4226-4238. doi: 10.1016/j.ymthe.2025.06.032. Epub 2025 Jun 28.
PubMed 40583275
Sherlock SP, Levy DI, McIntosh A, Shieh PB, Smith EC, McDonnell TG, Ryan KA, Delnomdedieu M, Binks M, Lal AK, Butterfield RJ. Cardiac safety of fordadistrogene movaparvovec gene therapy in Duchenne muscular dystrophy: Initial observations from a phase 1b trial. Mol Ther. 2025 Sep 3;33(9):4216-4225. doi: 10.1016/j.ymthe.2025.06.031. Epub 2025 Jun 28.
PubMed 40583273
Butterfield RJ, Shieh PB, Li H, Binks M, McDonnell TG, Ryan KA, Delnomdedieu M, Belluscio BA, Neelakantan S, Levy DI, Schwartz PF, Smith EC. AAV mini-dystrophin gene therapy for Duchenne muscular dystrophy: a phase 1b trial. Nat Med. 2025 Aug;31(8):2712-2721. doi: 10.1038/s41591-025-03750-3. Epub 2025 Jun 27.
PubMed 40579547

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Duchenne Muscular Dystrophy trials

Study at a glance

From the registry record, last updated by the sponsor on 15 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A PHASE 1B MULTICENTER, OPEN-LABEL, SINGLE ASCENDING DOSE STUDY TO EVALUATE THE SAFETY AND TOLERABILITY OF PF-06939926 IN AMBULATORY AND NON-AMBULATORY SUBJECTS WITH DUCHENNE MUSCULAR DYSTROPHY
ClinicalTrials.gov ID: NCT03362502
Acronym / sponsor ID: C3391001
Conditions: Duchenne Muscular Dystrophy
Keywords: gene therapy, mini-dystrophin, AAV, fordadistrogene movaparvovec
Phase: Phase 1
Study type: Interventional
Recruitment status: TerminatedReason stopped: All participants who have received fordadistrogene movaparvovec in any Pfizer study will now be assessed for long-term safety in 1 combined study: C3391003
Enrolment: 23 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 23 Jan 2018 (actual)
Primary completion: 28 Mar 2022 (actual)
Study completion: 28 Jul 2025 (actual)
First posted: 5 Dec 2017 (actual)
Results: Posted 20 Sep 2024

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Study design

Primary purpose: Treatment
Allocation: Not applicable
Intervention model: Sequential
Masking: None (open label)
Number of arms: 1

Arm	Type	Receives
PF-06939926	Experimental	Genetic: PF-06939926

Who may qualify

Ages: 4 years and older
Sex: Male only
Healthy volunteers: Not accepted
Age groups: Child, Adult, Older adult

Key inclusion criteria (16 listed)

Age as follows, based on ambulatory status:
Diagnosis of Duchenne muscular dystrophy confirmed by medical history and genetic testing;
Receipt of glucocorticoids for 6 months and a stable daily dose for at least 3 months prior to study entry;
Ability to tolerate magnetic resonance imaging (MRI) without sedation and with no contraindications to these procedures;
Ability to tolerate muscle biopsies under anesthesia with no contraindications to these procedures;

Key exclusion criteria (12 listed)

Receipt of live attenuated vaccination within 3 months prior to receiving PF-06939926 or exposure to an influenza (or other inactivated) vaccination or systemic antiviral and/or interferon therapy within 30 days prior to receipt of PF-06939926;
Prior exposure to any gene therapy agent, including exon-skipping agents;
Exposure to other investigational drugs within 30 days or 5 half-lives, whichever is longer;
Neutralizing antibodies (NAb) against adeno-associated virus, serotype 9 (AAV9);
Compromised cardiac function as indicated by left ventricular ejection fraction on cardiac MRI, as follows, based on ambulatory status:

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
PF-06939926Recombinant adeno-associated virus, serotype 9 (AAV9) carrying a truncated human dystrophin gene (mini-dystrophin) under the control of a muscle-specific promoter. Subjects will receive a single intravenous infusion of one of 2 dose levels.	Genetic	PF-06939926

Primary outcome

Number of Participants With All-Causality Treatment-Emergent Adverse Events (TEAEs) for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a treatment-emergent AE (TEAE). A serious AE (SAE) was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. Severe AE=an event that prevents normal everyday activities.
Number of Participants With All-Causality TEAEs by System Organ Class (SOC) and Preferred Term (PT) for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. For this outcome measure, TEAEs were reported according to Medical Dictionary for Regulatory Activities (MedDRA) version 25.0 SOC and PT.
Number of Participants With Treatment-Related TEAEs for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. An SAE was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. Severe AE=an event that prevents normal everyday activities. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Treatment-related AEs and SAEs were determined by the investigator.
Number of Participants With Treatment-Related TEAEs by SOC and PT for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. For this outcome measure, TEAEs were reported according to MedDRA version 25.0 SOC and PT. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Treatment-related AEs were determined by the investigator.
Number of Participants With All-Causality SAEs by SOC and PT for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. An SAE was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. For this outcome measure, TEAEs were reported according to MedDRA version 25.0 SOC and PT.
Number of Participants With Treatment-Related SAEs by SOC and PT for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Any AE that started following start of treatment of PF-06939926 was counted as a TEAE. An SAE was an untoward medical occurrence that resulted in death, was life-threatening (immediate risk of death), required in-patient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, resulted in congenital anomaly/birth defect, or was considered to be an important medical event. Treatment-related AE was any untoward medical occurrence attributed to study treatment in a participant who received study treatment. Treatment-related AEs and SAEs were determined by the investigator. For this outcome measure, TEAEs were reported according to MedDRA version 25.0 SOC and PT.
Number of Participants With Laboratory Test Abnormalities Without Regard to Baseline Abnormality for 1-Year Follow-Up - Hematology
Time frame: Baseline up to 1 year post dose of PF-06939926
Following hematologic parameters were analyzed for laboratory examination: hemoglobin, hematocrit, red blood cell (RBC) count, platelet count, white blood cell count, total neutrophils, absolute neutrophils (ANC), eosinophils, monocytes, basophils, lymphocytes, red blood cell indices, and haptoglobin. Laboratory abnormalities with occurrence in at least 1 participant are reported for this outcome measure. Baseline was defined as the last pre-dose measurement.
Number of Participants With Laboratory Test Abnormalities Without Regard to Baseline Abnormality for 1-Year Follow-Up - Clinical Chemistry
Time frame: Baseline up to 1 year post dose of PF-06939926
Following parameters for clinical chemistry were analyzed for laboratory examination: blood urea nitrogen (BUN) and creatinine, glucose, calcium, sodium, potassium, chloride, total CO2 (bicarbonate), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (direct and indirect bilirubin), alkaline phosphatase, uric acid, albumin, total protein, serum phosphorus, cystatin C, creatine kinase, creatine kinase myocardial b fraction (CK-MB), amylase, lipase, gamma-glutamyl transferase (GGT), C-reactive protein (CRP), and cardiac troponin I. Laboratory abnormalities with occurrence in at least 1 participant are reported for this outcome measure. Baseline was defined as the last pre-dose measurement.
Number of Participants With Laboratory Test Abnormalities Without Regard to Baseline Abnormality for 1-Year Follow-Up - Urinalysis
Time frame: Baseline up to 1 year post dose of PF-06939926
Following parameters for urinalysis were analyzed for laboratory examination: pH, glucose, protein, blood, ketones, nitrites, leukocyte esterase, and microscopy. Laboratory abnormalities with occurrence in at least 1 participant are reported for this outcome measure. Baseline was defined as the last pre-dose measurement.
Change From Baseline on Left Ventricular Ejection Fraction as Measured by Cardiac Magnetic Resonance Imaging (MRI) for 1-Year Follow-Up
Time frame: Baseline, 1 year post dose of PF-06839926 (Day 360)
Cardiac MRI was performed after thigh and upper limb MRI or on separate days within the required visit window. Change in LVEF is presented as percentages, and was calculated as [(stroke volume) / (end-diastolic volume)]*100%. Baseline is defined as the last pre-dose measurement. Change from baseline on Day 360 (ie, 1 year post dose) was reported for this outcome measure.
Number of Participants With Electrocardiograms (ECGs) Meeting the Pre-Defined Categorical Criteria for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
Triplicate ECG was performed after the participant had rested quietly for at least 10 minutes in a supine position. The pre-defined categorical criteria include PR interval aggregate (msec): value>=300, baseline>200 and percent change>=25%, baseline<=200 and percent change>=50%; QRS duration aggregate (msec): value>=140, percent change>=50%; QTcF interval aggregate (msec): 450<=value<480, 480<=value<500, value>=500, 30<=change<60, change>=60. Only the category(ies) with at least 1 participant meeting the pre-defined criterion is/are reported for this outcome measure. Baseline for ECG was defined as the measurement before the Day 1 study drug administration.
Number of Participants With Positive Responses on Columbia-Suicide Severity Rating Scale (C-SSRS) According to the Columbia Classification Algorithm of Suicide Assessment (C-CASA) Categories
Time frame: Baseline, Day 7, Day 14, Day 180, and Day 360
C-SSRS is a participant rated questionnaire to assess whether participant experienced the following: completed suicide(1), suicide attempt(2)("Yes" on "actual attempt"), preparatory acts toward imminent suicidal behavior(3)("Yes" on "preparatory acts or behavior"), suicidal ideation(4)("Yes" on "wish to be dead","non-specific active suicidal thoughts","active suicidal ideation with methods without intent to act or some intent to act, without specific plan or with specific plan and intent), any suicidal behavior or ideation, self-injurious behavior(7)("Yes" on "Has subject engaged in non-suicidal self-injurious behavior"). Yes/No responses are mapped to C-CASA categories. C-SSRS was conducted with the participant's care giver/legal guardian on the participant's behalf throughout the study for participants<=12 years of age at screening. Baseline is defined as the last predose measurement. Number of participants with responses of "Yes" is reported for this outcome measure.
Number of Participants With Vital Signs Meeting the Pre-Defined Categorical Criteria for 1-Year Follow-Up
Time frame: Baseline up to 1 year post dose of PF-06939926
Vital signs consisted of blood pressure, respiratory rate, and heart rate, was obtained with these measurements at the following timepoints: within 30 minutes before and approximately 30 minutes, 1, 2, 4, 8, and 24 hours after the start of the infusion, and on Days 4, 7, 10, 14, 30, 90, 180, and 360. Baseline was defined as the last pre-dose recording. Number of participants who had at least 1 vital sign measurement at the specified timepoints meeting the pre-defined criteria from baseline up to the end of 1-year follow-up is reported for this outcome measure.

Results and safety

Results posted to the registry on 20 Sep 2024, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
PF-06939926: Low Dose, Ambulatory Cohort	3	3
PF-06939926: High Dose, Ambulatory Cohort	16	16
PF-06939926: High Dose, Non-Ambulatory Cohort	3	2

Primary outcome: Number of Participants With All-Causality Treatment-Emergent Adverse Events (TEAEs) for 1-Year Follow-Up

Time frame: Baseline up to 1 year post dose of PF-06939926. Count of participants. Unit: Participants

Measure	PF-06939926: Low Dose, Ambulatory Cohort n = 3	PF-06939926: High Dose, Ambulatory Cohort n = 16	PF-06939926: High Dose, Non-Ambulatory Cohort n = 3
TEAEs	3	16	3
SAEs	0	3	2
Severe AEs	1	2	2

Population analysed: Includes all enrolled participants who received PF-06939926. Participants were analyzed according to the intervention they actually received.

Primary outcome: Number of Participants With All-Causality TEAEs by System Organ Class (SOC) and Preferred Term (PT) for 1-Year Follow-Up

Time frame: Baseline up to 1 year post dose of PF-06939926. Count of participants. Unit: Participants

Measure	PF-06939926: Low Dose, Ambulatory Cohort n = 3	PF-06939926: High Dose, Ambulatory Cohort n = 16	PF-06939926: High Dose, Non-Ambulatory Cohort n = 3
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, Total	2	9	1
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Anaemia	0	2	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Haemolysis	0	1	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Haemolytic uraemic syndrome	0	0	1
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Leukocytosis	1	0	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Lymphopenia	1	0	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Thrombocytopenia	0	9	0
SOC: CARDIAC DISORDERS, Total	0	0	2

Population analysed: Includes all enrolled participants who received PF-06939926. Participants were analyzed according to the intervention they actually received.

Primary outcome: Number of Participants With Treatment-Related TEAEs for 1-Year Follow-Up

Time frame: Baseline up to 1 year post dose of PF-06939926. Count of participants. Unit: Participants

Measure	PF-06939926: Low Dose, Ambulatory Cohort n = 3	PF-06939926: High Dose, Ambulatory Cohort n = 16	PF-06939926: High Dose, Non-Ambulatory Cohort n = 3
TEAEs	3	15	3
SAEs	0	3	2
Severe AEs	0	2	2

Population analysed: Includes all enrolled participants who received PF-06939926. Participants were analyzed according to the intervention they actually received.

Primary outcome: Number of Participants With Treatment-Related TEAEs by SOC and PT for 1-Year Follow-Up

Time frame: Baseline up to 1 year post dose of PF-06939926. Count of participants. Unit: Participants

Measure	PF-06939926: Low Dose, Ambulatory Cohort n = 3	PF-06939926: High Dose, Ambulatory Cohort n = 16	PF-06939926: High Dose, Non-Ambulatory Cohort n = 3
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, Total	2	9	1
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Anaemia	0	2	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Haemolysis	0	1	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Haemolytic uraemic syndrome	0	0	1
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Leukocytosis	1	0	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Lymphopenia	1	0	0
SOC: BLOOD AND LYMPHATIC SYSTEM DISORDERS, PT: Thrombocytopenia	0	9	0
SOC: CARDIAC DISORDERS, Total	0	0	1

Population analysed: Includes all enrolled participants who received PF-06939926. Participants were analyzed according to the intervention they actually received.

Adverse events

Time frame: Baseline up to the end of 1-year follow-up (approximately 360 days). Other adverse events reported at 5% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
PF-06939926: Low Dose, Ambulatory Cohort	0 of 3 (0%)	3 of 3 (100%)	0 of 3
PF-06939926: High Dose, Ambulatory Cohort	3 of 16 (18.8%)	16 of 16 (100%)	0 of 16
PF-06939926: High Dose, Non-Ambulatory Cohort	2 of 3 (66.7%)	3 of 3 (100%)	1 of 3

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 15 Sep 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 40753271Walsh J, Palandra J, Duriga N, Beidler D, McIntosh A, Binks M, Neubert H. Dystrophin/mini-dystrophin expression analysis by immunoaffinity liquid chromatography-tandem mass spectrometry after gene therapy for DMD. Gene Ther. 2025 Dec;32(6):573-580. doi: 10.1038/s41434-025-00554-5. Epub 2025 Aug 2.
Derived from this study: PubMed 40583275Byrne BJ, Butterfield RJ, Shieh PB, Smith EC, Licht C, Binks M, Casinghino S, Delnomdedieu M, Ravindra KC, McDonnell T, Ryan K, Schulz M, Shen Q, Shi H, Sirivelu MP, Vaidya VS, Whiteley L, Levy DI. Complement activation in a phase Ib study of fordadistrogene movaparvovec for Duchenne muscular dystrophy. Mol Ther. 2025 Sep 3;33(9):4226-4238. doi: 10.1016/j.ymthe.2025.06.032. Epub 2025 Jun 28.
Derived from this study: PubMed 40583273Sherlock SP, Levy DI, McIntosh A, Shieh PB, Smith EC, McDonnell TG, Ryan KA, Delnomdedieu M, Binks M, Lal AK, Butterfield RJ. Cardiac safety of fordadistrogene movaparvovec gene therapy in Duchenne muscular dystrophy: Initial observations from a phase 1b trial. Mol Ther. 2025 Sep 3;33(9):4216-4225. doi: 10.1016/j.ymthe.2025.06.031. Epub 2025 Jun 28.
Derived from this study: PubMed 40579547Butterfield RJ, Shieh PB, Li H, Binks M, McDonnell TG, Ryan KA, Delnomdedieu M, Belluscio BA, Neelakantan S, Levy DI, Schwartz PF, Smith EC. AAV mini-dystrophin gene therapy for Duchenne muscular dystrophy: a phase 1b trial. Nat Med. 2025 Aug;31(8):2712-2721. doi: 10.1038/s41591-025-03750-3. Epub 2025 Jun 27.
To obtain contact information for a study center near you, click here.Link provided by the sponsor.
Individual participant dataSharing planned: No. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Pfizer CT.gov Call Center study director

Pfizer

22 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing PF-06939926 in people with Duchenne Muscular Dystrophy, run by Pfizer at 22 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 16 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: stopped early, as of the sponsor's last update on 15 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 22 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 20 Sep 2024). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants With All-Causality Treatment-Emergent Adverse Events (TEAEs) for 1-Year Follow-Up (time frame: Baseline up to 1 year post dose of PF-06939926). The study lists 13 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT03362502, which also lists 4 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Sep 2025; AzTrials last refreshed its copy on 26 Oct 2026.