Phase 2a Extension Study of Ataluren (PTC124) in Duchenne Muscular Dystrophy (DMD)

Study Overview
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Brief Summary
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Duchenne muscular dystrophy (DMD) is a genetic disorder that develops in boys. It is caused by a mutation in the gene for dystrophin, a protein that is important for maintaining normal muscle structure and function. Loss of dystrophin causes muscle fragility that leads to weakness and loss of walking ability during childhood and teenage years. A specific type of mutation, called a nonsense (premature stop codon) mutation, is the cause of DMD in approximately 10-15% of boys with the disease. Ataluren is an orally-delivered, investigational drug that has the potential to overcome the effects of the nonsense mutation. This study is a Phase 2a extension trial that will evaluate the long-term safety of ataluren in boys with nonsense mutation DMD, as determined by adverse events and laboratory abnormalities. The study will also assess changes in walking, muscle function, strength, and other important clinical and laboratory measures.

Detailed Description
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This Phase 2a, multicenter, open-label safety and efficacy study will be performed at 3 sites in the United States. The study will enroll up to 38 participants with nonsense mutation Duchenne muscular dystrophy who participated in a previous Phase 2a study of ataluren (Protocol Number PTC124-GD-004-DMD [NCT00264888]). Participants will receive study drug 3 times per day (at breakfast, lunch, and dinner) for approximately 96 weeks (approximately 2 years). Study assessments will be performed at clinic visits during screening, every 6 weeks for the first 24 weeks, and then every 12 weeks until the end of the study. Additional safety laboratory testing, which may be performed at the investigational site or at an accredited local laboratory or clinic, is required every 3 weeks for the first 24 weeks and then every 6 weeks from Week 24 to Week 48. Participants will have a biceps muscle biopsy before ataluren treatment and again after 24 weeks of ataluren treatment to evaluate changes in muscle dystrophin expression. An evaluation of the effects of ataluren on corticosteroid pharmacokinetics will be performed. Associated with this ataluren clinical trial is a substudy that will use magnetic resonance evaluations to assess changes in the composition of muscles of the legs.

Official Title
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A Phase 2a Extension Study of PTC124 in Subjects With Nonsense-Mutation-Mediated Duchenne Muscular Dystrophy

Conditions
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Duchenne Muscular Dystrophy

Intervention / Treatment
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* Drug: Ataluren


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Completion of ataluren treatment in the previous Phase 2a study (Protocol PTC124-GD-004-DMD). Ability to provide written informed consent (parental/guardian consent if applicable)/assent (if <18 years of age). Confirmed screening laboratory values within the central laboratory ranges. In participants who are sexually active, willingness to abstain from sexual intercourse or employ a barrier or medical method of contraception during ataluren administration and the 6-week follow up period. Willingness and ability to comply with scheduled visits, drug administration plan, study procedures, laboratory tests, and study restrictions. Exclusion Criteria: Treatment with systemic aminoglycoside antibiotics within 3 months prior to start of study treatment. Treatment with warfarin within 1 month prior to start of study treatment. Known hypersensitivity to any of the ingredients or excipients of the study drug (Litesse® UltraTM [refined polydextrose], polyethylene glycol 3350, Lutrol® micro F127 [poloxamer 407], mannitol 25C, crospovidone XL10, hydroxyethyl cellulose, vanilla, Cab-O-Sil® M5P [colloidal silica], and magnesium stearate). Exposure to another investigational drug within 2 months prior to start of study treatment. History of major surgical procedure within 1 month prior to start of study treatment. Ongoing immunosuppressive therapy (other than corticosteroids). Ongoing participation in any other clinical trial (except for sub-studies specifically approved by PTC Therapeutics). Clinically significant symptoms and signs of congestive heart failure (CHF) (American College of Cardiology/American Heart Association Stage C or Stage D). Prior or ongoing medical condition (for example, concomitant illness, psychiatric condition, behavioral disorder, alcoholism, drug abuse), medical history, physical findings, electrocardiogram findings, or laboratory abnormality that, in the Investigator's opinion, could adversely affect the safety of the participant, makes it unlikely that the course of treatment or follow-up would be completed, or could impair the assessment of study results.
Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Ataluren<br>Participants will receive ataluren 3 times per day with meals at doses of 20 milligrams per kilogram (mg/kg) (breakfast), 20 mg/kg (lunch), and 40 mg/kg (dinner) for up to 89 weeks. | Drug: Ataluren<br>* Ataluren will be provided as a vanilla-flavored powder to be mixed with milk. Dosing based on participant body weight<br>* Other names: PTC124;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants With Treatment Emergent Adverse Events (TEAEs) | TEAE: any untoward medical occurrence or undesirable event(s) that begins or worsens following administration of the study drug, whether or not considered related to the treatment by the Investigator. Severity of an adverse event (AE) was classified as: mild (does not interfere with usual function), moderate (interferes with usual function; may require medical intervention), severe (interferes significantly with usual function; likely require medical intervention), life-threatening, and fatal. Drug-related AEs: AEs with a possible or probable relationship to study drug. Serious AEs: death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, a congenital anomaly or birth defect, or an important medical event that jeopardized participant and required medical intervention. A summary of other non-serious AEs and all serious AEs, regardless of causality is located in Reported AE section. | Baseline up to Week 89 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in 6-Minute Walk Distance (6MWD) as Measured by the 6-minute Walk Test (6MWT) | The 6MWD was assessed in participants who were ambulatory using standardized procedures. Participants were not permitted to use assistive devices during the 6MWD test. Only the results of the participant's best valid test at each visit were included in the analysis. The mean change from baseline in the distance the participant walked is reported. | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Proximal Muscle Function as Assessed by Speed During Timed Function Tests | Timed function tests included time to stand from supine position (rise to standing), time to run/walk 10 meters (m), and time to ascend/descend 4 stairs. Timed function tests were assessed in ambulatory participants. A decrease from baseline reflects faster completion of the functional task and, thus, better muscle function. If the time taken to perform a test exceeded 30 seconds or if a participant could not perform the test due to disease progression (PD), a value of 30 seconds was used. Test results were set to missing in the analysis for participants who could not perform the tests for reasons other than PD (for example, bone fracture). | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Standing From Supine Position as Assessed by Method Scores During Timed Function Tests | Timed test evaluations included scoring of method that ambulatory participants used to complete test. Scale for method used for standing from supine position: 1) Unable to stand from supine, even with use of a chair. 2) Assisted Gowers, requires furniture to rise from supine to full upright posture. 3) Full Gowers, rolls over, stands with both hands climbing up legs to above knees to achieve full upright posture. 4) Half Gowers, rolls over, stands up with 1 hand support on lower legs. 5) Rolls to side and/or stands with 1 or both hands on floor to start to rise but does not touch legs. 6) Stands without rolling over or using hands. Increases from baseline are indicative of improving ability to perform functional task. If a participant could not perform a timed function test because of PD, a method value of 1 was assigned in analysis. Test results set to missing in analysis for participants who could not perform tests for reasons other than PD (for example, bone fracture). | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Run/Walk 10-Meters as Assessed by Method Scores During Timed Function Tests | Timed test evaluations included scoring of method that ambulatory participants used to complete test. Scale for method used to run/walk 10-meters: 1) Unable to walk independently. 2) Unable to walk independently but can walk with knee-ankle-foot orthoses (KAFOs) or with support from a person 3) Highly adapted, wide-based lordotic gait, cannot increase walking speed. 4) Moderately adapted gait, can pick up speed but cannot run. 5) Able to pick up speed but runs with a double stance phase (that is, cannot achieve both feet off the ground). 6) Runs and gets both feet off the ground (with no double-stance phase). At the visit, if a participant could not perform a timed function test because of PD, a method value of 1 was assigned in analysis. Test results set to missing in analysis for participants who could not perform tests for reasons other than PD (for example, bone fracture). | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Ascending 4 Stairs as Assessed by Method Scores During Timed Function Tests | Timed test evaluations included scoring of method that ambulatory participants used to complete test. Scale for method used to ascend 4 stairs: 1) Unable to climb 4 standard stairs. 2) Climbs 4 standard stairs marking time (climbs 1 foot at a time, with both feet on a step before moving to next step), using both arms on 1 or both handrails. 3) Climbs 4 standard stairs marking time using 1 arm on 1 handrail. 4) Climbs 4 standard stairs marking time not needing handrail. 5) Climbs 4 standard stairs alternating feet, needs handrail for support. 6) Climbs 4 standard stairs alternating feet, not needing handrail support. At the visit, if a participant could not perform a timed function test because of PD, a method value of 1 was assigned in analysis. Test results set to missing in analysis for participants who could not perform tests for reasons other than PD (for example, bone fracture). | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Descending 4 Stairs as Assessed by Method Scores During Timed Function Tests | Timed test evaluations included scoring of method that ambulatory participants used to complete test. Scale for method used to descend 4 stairs: 1) Unable to descend 4 standard stairs. 2) Descends 4 standard stairs marking time (climbs 1 foot at a time, with both feet on a step before moving to next step), using both arms on 1 or both handrails. 3) Descends 4 standard stairs marking time, using 1 arm on 1 handrail. 4) Descends 4 standard stairs marking time, not needing handrail. 5) Descends 4 standard stairs alternating feet in both directions, needs handrail for support. 6) Descends 4 standard stairs alternating feet, not needing handrail support. At the visit, if a participant could not perform a timed function test because of PD, a method value of 1 was assigned in analysis. Test results set to missing in analysis for participants who could not perform tests for reasons other than PD (for example, bone fracture). | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Force Exerted During Knee Flexion and Extension, Elbow Flexion and Extension, Shoulder Abduction, and Hand Grip as Assessed by Myometry | Upper extremity myometry was performed using a hand-held dynamometer following standardized procedures. With this system, evaluators judged the strength of each muscle using an 11-point descriptive scoring system. From the individual muscle-group scores, a total composite score was derived. Bilateral assessments were done, and 3 measurements were recorded from each muscle group on each side, when possible. The best of the 3 replicates was used in the analysis. An increase from Baseline is reflective of increased muscle strength, whereas a decrease from Baseline is reflective of decreased muscle strength. Participants who became unable to perform a myometry test because of disease progression were assigned a value of 0 for each visit at which the participant was no longer able to perform the test. Test results were set to missing in the analysis for participants who could not perform the tests for reasons other than disease progression (for example, bone fracture). | Baseline, Week (Wk) 48 and Wk 60 | 
| Change in Resting, Active, and Recovery Heart Rate as Assessed by Heart Rate Monitoring With the Polar RS400 | Heart rate was measured with a Polar RS400 heart rate monitor, which consists of a transmitter strap worn around the chest and a wristwatch receiver. The monitor produces a digital text file with 1 value per minute that represents the mean heart rate for that minute. Mean heart rate values were collected before, during, and after the 6MWT. The participant rested for 5 minutes in a sitting position before the 6MWT, and the mean heart rate for the last minute of this rest period was obtained and documented as the resting heart rate. During the 6MWT, the mean heart rate was collected and documented as the active heart rate. After completing the 6MWT and resting for 3 minutes, the mean heart rate for 1 minute was obtained and documented as the recovery heart rate. | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Verbal Memory and Attention as Assessed by the Digit Span Task | The digit span task is a 2-part (forward and backward) test in which a series of digits (3 to 9) were presented to participant in an auditory format only. For forward condition, the participant was to repeat digits back in the order they were presented. For backward condition, the participant was to reverse the order of presentation. Maximum score for each part (digit forward and digit backward) of task is 14; participants received a score of 2 points if they passed both trials, score of 1 point if they passed only 1 trial, and score of 0 points if they failed both trials. A raw score of total number of correct forward and backward responses was age-normalized by subtracting corresponding mean and dividing by corresponding standard deviation of a reference population for that age. For each forward and backward result, the resulting Z score was transformed into percentile rank of normal distribution. Change from Baseline in number of digits recalled forward and backward is reported. | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Participant-Reported Health-Related Quality of Life (HRQL) as Measured by the Pediatric Quality of Life Inventory (PedsQL) Inventory | The PedsQL Generic Core Scales comprises 23 questions, which are grouped into 4 scales (physical functioning, emotional functioning, social functioning, and school functioning); the fatigue-specific module included an additional 18 questions. The appropriate age-specific version was completed. On PedsQL Generic Core Scales, items were reversed scored and linearly transformed to a 0 to 100 scale so that higher scores indicate a better HRQL (0=100, 1=75, 2=50, 3=25, and 4=0). Mean is the sum of the items over the number of items that were answered (which accounts for missing data) to create scale scores. If >50% of the items in a scale were missing, the scale score was not computed. Mean Total Scale Score is the sum of all of the items over the number of items that were answered on all scales. | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Parent- or Caregiver-Reported HRQL as Measured by the PedsQL Inventory | The PedsQL Generic Core Scales comprises 23 questions, which are grouped into 4 scales (physical functioning, emotional functioning, social functioning, and school functioning); the fatigue-specific module included an additional 18 questions. The appropriate age-specific version was completed. On PedsQL Generic Core Scales, items were reversed scored and linearly transformed to a 0 to 100 scale so that higher scores indicate a better HRQL (0=100, 1=75, 2=50, 3=25, and 4=0). Mean is the sum of the items over the number of items that were answered (which accounts for missing data) to create scale scores. If >50% of the items in a scale were missing, the scale score was not computed. Mean Fatigue Scale Score is the sum of the items over the number of items that were answered in the Emotional, Social, and School Functioning Scales. Mean Total Scale Score is the sum of all of the items over the number of items that were answered on all scales. | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Serum Creatine Kinase (CK) Levels | Serum CK concentrations (as measured by the central laboratory) were quantified from the blood samples that were collected as part of the safety laboratory evaluations. The normal range for CK is 18 to 363 units/liter (U/L). | Baseline, Week 48 and Week 60 | 
| Change From Baseline in Dystrophin Expression on Biceps Muscle Biopsy as Measured by Immunofluorescence Staining of the Sarcolemmal Membrane With an Antibody to the C-Terminal Portion of the Dystrophin Protein | The biceps muscle was biopsied from 1 arm for confirmation of the absence or low levels of dystrophin prior to treatment initiation and from the other arm to assess for production of dystrophin post-treatment. Muscle tissue sections were processed and immunostained to detect muscle membrane-localized dystrophin. An increase in value indicates dystrophin production. | Baseline, Week 24 | 
| Study Drug Compliance | Study drug compliance was assessed by the participant daily diary and quantification of used and unused study drug. Compliance was assessed in terms of the amount of drug actually taken relative to the amount that was prescribed. Physician-prescribed dose reductions and interruptions were factored into the calculations. Not recorded applies only to the days on which all dosing information was missing or for missing days. Invalid entries in the participant daily diary were assigned values of 0.0 for percentage of doses taken and 99.0 for percentage of doses not recorded. | Baseline up to Week 89 | 
| Pharmacokinetics: Ataluren Plasma Exposure in All Participants | Blood for ataluren concentrations over a 24-hour period was to be collected on Day 2 of Week 1 and Day 2 of Week 6. Analysis of the blood samples was to be conducted using a validated high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) method with a lower limit of quantitation (LLOQ) of 0.5 micrograms/milliliters (μg/mL). Plasma concentrations below qualification (BQ) is treated as 0 in the summary calculation. | 0 (pre-dose), 0.5, 1, 2, 3, and 4 hours post-morning dose and 0 (pre-dose) and 2 hours post-midday dose on Day 2 of Week 1 and Day 2 of Week 6 | 
| Pharmacokinetics: Ataluren Plasma Exposure in Ambulatory Participants | Blood for ataluren concentrations were collected on Day 2 of Week 1 and Day 2 of Week 6. Analysis of the blood samples was to be conducted using a validated HPLC-MS/MS method with a LLOQ of 0.5 μg/mL. Plasma concentrations BQ is treated as 0 in the summary calculation. | 0 (pre-dose), 0.5, 1, 2, 3, and 4 hours post-morning dose and 0 (pre-dose) and 2 hours post-midday dose on Day 2 of Week 1 and Day 2 of Week 6 | 
| Corticosteroid Plasma Concentrations as Assessed by a Validated Bioanalytical Method, in Participants Who Received a Daily Corticosteroid Regimen With Prednisone or Deflazacort | Blood for prednisone and deflazacort concentrations were collected on Day 2 of Week 1 and Day 2 of Week 6. Plasma samples for the determination of prednisone concentrations were analyzed using a validated HPLC/MS/MS method, with LLOQs of 1.00 nanograms/milliliters (ng/mL). Prednisone concentrations <1.01 are treated as 1.01 in the summary calculation. Plasma samples for the determination of 21-desacetyl deflazacort concentrations were analyzed using a validated HPLC/MS/MS method with an LLOQ of 1.0 ng/mL. Deflazacort concentrations BQ are treated as 0 in the summary calculation. | 0 (pre-dose), 0.5, 1, 2, 3, and 4 hours post-morning dose and 0 (pre-dose) and 2 hours post-midday dose on Day 2 of Week 1 and Day 2 of Week 6 | 
| Change in Muscle Composition as Assessed by Limb Magnetic Resonance (MR) Testing | This Outcome Measure is an exploratory study objective and data were not collected or analyzed for this extension study. | Baseline, Week 48, Week 60 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Duchenne muscular dystrophy, Nonsense mutation, Premature stop codon, DMD, PTC124, Ataluren