Trial · NCT03323749

A Trial to Evaluate Safety and Efficacy of Elamipretide Primary Mitochondrial Myopathy Followed by Open-Label Extension

NCT03323749, Phase 3, Terminated, Stealth BioTherapeutics Inc.; results first posted 2021-04-02

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. A Trial to Evaluate Safety and Efficacy of Elamipretide Primary Mitochondrial Myopathy Followed by Open-Label Extension. Trials, record NCT03323749. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT03323749

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Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: A Trial to Evaluate Safety and Efficacy of Elamipretide Primary Mitochondrial Myopathy Followed by Open-Label Extension
NCT number: NCT03323749
Status: Terminated
Phases: Phase 3
Enrollment: 218 participants, actual
Lead sponsor: Stealth BioTherapeutics Inc.
Conditions: Primary Mitochondrial Myopathy
Interventions: elamipretide, placebo comparator, elamipretide open label treatment
First posted: 2017-10-27
Last updated: 2022-01-24
Results first posted: 2021-04-02

Source ClinicalTrials.gov

Registered outcomes6

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Six-minute Walk Test (6MWT)	Baseline to 24 weeks	Change From Baseline in Distance Walked (meters) on the Six-Minute Walk Test by Visit
Primary	Total Fatigue Score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA)	Baseline to 24 weeks	Change from Baseline in Total fatigue score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA) by visit. Each individual item score ranges from 1 (none) to 4 (severe). The total fatigue score ranges from 4-16. Lower values represent a better outcome. The total fatigue score is the sum of question 1 through question 4 on the Primary Mitochondrial Myopathy Symptom Assessment.
Secondary	Fatigue During Activities Score on the Primary Mitochondrial Disease Symptom Assessment (PMMSA).	Baseline to 24 weeks	Change from baseline in Fatigue During Activities. Fatigue During Activities is the sum of question 2 (tiredness during activities) and question 4 (muscle weakness during activities.) The four response options are: 1=Not at all, 2=Mild, 3=Moderate, and 4=Severe. Raw scores for each subject range from 2-8. A lower score means a better outcome, with less fatigue. A higher score means a worse outcome, with more fatigue.
Secondary	Neuro-QoL Fatigue Activities of Daily Living	Baseline to 24 weeks	Change From Baseline in Neuro-QoL Fatigue Activities of Daily Living by Visit. Each individual item score ranges from 1-5. Total raw score for the entire item bank ranges from 19-95. Raw scores will be calibrated using Item Response Theory Model. Lower values represent a better outcome. Individual items will be summed to calculate total scores.
Secondary	Change From Baseline in the Most Bothersome Symptom Score on the Primary Mitochondrial Myopathy Symptoms Assessment	Baseline to 24 weeks	The item score rangers from 1 (none) to 4 (severe). Lower values represent a better outcome. The most bothersome score is the average of the identified most bothersome symptom of the Primary Mitochondrial Myopathy Symptom Assessment by each subject.
Secondary	Neuro-QoL Fatigue Short Form Score	24 Weeks	Change From Baseline in Neuro-QoL Fatigue - Short Form: Total T-Scores by Visit. The Neuro-QoL Fatigue Short Form is comprised of the sum of the first 8 questions of the Neuro-QoL Item Bank v1.0 - Fatigue. Each question is scored as following: 1=Never, 2=Rarely, 3=Sometimes, 4=Often, and 5=Always. The questions include: I felt exhausted, I felt that I had no energy, I felt fatigued, I was too tired to do my household chores, I was too tired to leave the house, I was frustrated by being too tired to do the things I wanted to do, I felt tired, and I had to limit my social activity because I was tired. T-scores are calculated from the short form scoring table provided by the instrument authors (Neuro-QoL User Manual, 2015). T-score distributions rescale raw scores into standardized scores with a mean of 50 and a standard deviation (SD) of 10. Change from baseline: Negative numbers mean less fatigue, better outcome, positive score means more fatigue, worse outcome.

Source ClinicalTrials.gov

Outcomes6

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Six-minute Walk Test (6MWT)	Baseline to 24 weeks	All participants for whom 6MWT was measured	meters	MEAN
PRIMARY	Total Fatigue Score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA)	Baseline to 24 weeks	All participants for whom Total Fatigue Score (Q1 to Q4) Based on PMMSA by Visit was measured	score on a scale	MEAN
SECONDARY	Fatigue During Activities Score on the Primary Mitochondrial Disease Symptom Assessment (PMMSA).	Baseline to 24 weeks	All participants for whom Fatigue During Activities was measured.	score on a scale	MEAN
SECONDARY	Neuro-QoL Fatigue Activities of Daily Living	Baseline to 24 weeks	All participants for whom Change From Baseline in Neuro-QoL Fatigue Activities of Daily Living by Visit was measured.	score on a scale	MEAN
SECONDARY	Change From Baseline in the Most Bothersome Symptom Score on the Primary Mitochondrial Myopathy Symptoms Assessment	Baseline to 24 weeks	All participants for whom Most Bothersome Symptom Score (PMMSA) by Visit was measured.	score on a scale	MEAN
SECONDARY	Neuro-QoL Fatigue Short Form Score	24 Weeks	All participants for whom Neuro-QoL Fatigue Short Form Score T-scores were measured.	score on a scale	MEAN

Source ClinicalTrials.gov

Results by group36

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Category	Value	Spread	Units
Six-minute Walk Test (6MWT)	Elamipretide	Week 4	16.243	Standard Deviation 42.0071	meters
Six-minute Walk Test (6MWT)	Placebo	Week 4	7.811	Standard Deviation 39.5737	meters
Six-minute Walk Test (6MWT)	Elamipretide	Week 12	18.286	Standard Deviation 47.7766	meters
Six-minute Walk Test (6MWT)	Placebo	Week 12	8.801	Standard Deviation 52.1093	meters
Six-minute Walk Test (6MWT)	Elamipretide	Week 24	15.330	Standard Deviation 61.4860	meters
Six-minute Walk Test (6MWT)	Placebo	Week 24	17.386	Standard Deviation 51.6956	meters
Total Fatigue Score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA)	Elamipretide	Week 4	-1.01	Standard Deviation 1.714	score on a scale
Total Fatigue Score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA)	Placebo	Week 4	-1.08	Standard Deviation 1.865	score on a scale
Total Fatigue Score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA)	Elamipretide	Week 12	-1.08	Standard Deviation 1.775	score on a scale
Total Fatigue Score on the on the Primary Mitochondrial Myopathy Symptom Assessment (PMMSA)	Placebo	Week 12	-1.26	Standard Deviation 2.259	score on a scale

1 to 10 of 36Source ClinicalTrials.gov

See all 36 results by group

Participant flow12

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Double-blind Period	STARTED	Double-Blind Elamipretide, Then Open Label Elamepretide	109
Double-blind Period	STARTED	Double-Blind Placebo Then Open-Label Elamepretide	109
Double-blind Period	COMPLETED	Double-Blind Elamipretide, Then Open Label Elamepretide	102
Double-blind Period	COMPLETED	Double-Blind Placebo Then Open-Label Elamepretide	103
Double-blind Period	NOT COMPLETED	Double-Blind Elamipretide, Then Open Label Elamepretide	7
Double-blind Period	NOT COMPLETED	Double-Blind Placebo Then Open-Label Elamepretide	6
Open-Label Period	STARTED	Double-Blind Elamipretide, Then Open Label Elamepretide	93
Open-Label Period	STARTED	Double-Blind Placebo Then Open-Label Elamepretide	103
Open-Label Period	COMPLETED	Double-Blind Elamipretide, Then Open Label Elamepretide	0
Open-Label Period	COMPLETED	Double-Blind Placebo Then Open-Label Elamepretide	0

1 to 10 of 12Source ClinicalTrials.gov

See all 12 participant flow

Adverse events316

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk
other	Injection site erythema	General disorders	Double-Blind Elamipretide	94	109
other	Injection site erythema	General disorders	Double-Blind Placebo	31	109
other	Injection site erythema	General disorders	Open-Label Elamipretide	66	93
other	Injection site erythema	General disorders	Open-Label Placebo	87	103
other	Injection site pruritus	General disorders	Double-Blind Elamipretide	82	109
other	Injection site pruritus	General disorders	Double-Blind Placebo	10	109
other	Injection site pruritus	General disorders	Open-Label Elamipretide	57	93
other	Injection site pruritus	General disorders	Open-Label Placebo	81	103
other	Injection site pain	General disorders	Double-Blind Elamipretide	43	109
other	Injection site pain	General disorders	Double-Blind Placebo	20	109

1 to 10 of 316Source ClinicalTrials.gov

See all 316 adverse events

Adverse event totals12

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Double-Blind Elamipretide	0	109
Total, all-cause mortality	Double-Blind Placebo	0	109
Total, all-cause mortality	Open-Label Elamipretide	0	93
Total, all-cause mortality	Open-Label Placebo	0	103
Total, other adverse events	Double-Blind Elamipretide	107	109
Total, other adverse events	Double-Blind Placebo	83	109
Total, other adverse events	Open-Label Elamipretide	88	93
Total, other adverse events	Open-Label Placebo	102	103
Total, serious adverse events	Double-Blind Elamipretide	5	109
Total, serious adverse events	Double-Blind Placebo	3	109

1 to 10 of 12Source ClinicalTrials.gov

See all 12 adverse event totals

Papers2

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as	Source
37268435	DERIVED	PubMed
39574155	DERIVED	PubMed

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT03323749

GET https://conductscience.org/api/trials/v1/NCT03323749/results?page=2

API reference For AI assistants