Trial Outcomes & Findings for Study of ACE-083 in Patients With Facioscapulohumeral Muscular Dystrophy (FSHD) (NCT NCT02927080)

Last Updated: 2022-09-26

Results Overview

The number of participants that had a least one Treatment Emergent Adverse Event for the duration of each of the respective study parts.

Recruitment status

TERMINATED

Study phase

PHASE2

Target enrollment

95 participants

Primary outcome timeframe

From initiation of treatment to Day 106 for Part 1 and Day 190 for Part 2

Results posted on

2022-09-26

Participant Flow

First subject enrolled 22 November 2016, last subject completed 09 October 2019. The study was divided into parts; Part 1 was an open-label dose escalation study and had 6 cohorts and Part 2 was a randomized double-blind placebo controlled trial. Participants were recruited from 23 study centers in 3 countries (US, Canada and Spain).

Participant milestones

Participant milestones
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) Unilateral ACE-083 150 mg Tibialis Anterior (TA) unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) Unilateral ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) Bilateral ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) Unilateral ACE-083 150 mg Biceps Brachii (BB) unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) Unilateral ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) Unilateral ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo-BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Overall Study STARTED	6	6	6	6	7	6	15	14	15	14
Overall Study Open-Label Extension From Part 2 Double Blind-Placebo Controlled	0	0	0	0	0	0	14	13	14	12
Overall Study COMPLETED	6	5	6	6	6	6	7	5	12	7
Overall Study NOT COMPLETED	0	1	0	0	1	0	8	9	3	7

Reasons for withdrawal

Reasons for withdrawal
Measure	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) Unilateral ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) Unilateral ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo-BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Overall Study Withdrawal by Subject	0	1	1	1	0	2
Overall Study Willingness to comply with protocol	0	0	0	0	0	1
Overall Study Study terminated by Sponsor	0	0	6	7	2	3
Overall Study Adverse Event	1	0	0	1	0	1
Overall Study Other	0	0	1	0	1	0

Baseline Characteristics

Study of ACE-083 in Patients With Facioscapulohumeral Muscular Dystrophy (FSHD)

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150mg n=6 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200mg n=6 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200mg n=6 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=6 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg n=7 Participants ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg n=6 Participants ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) n=15 Participants Double-Blind, Placebo-Controlled Placebo- TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein.	Placebo (Part 2, DB-PC) Biceps Brachii (BB) n=15 Participants Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Total n=95 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants
Age, Categorical Between 18 and 65 years	6 Participants n=5 Participants	6 Participants n=7 Participants	6 Participants n=5 Participants	5 Participants n=4 Participants	6 Participants n=21 Participants	6 Participants n=8 Participants	15 Participants n=8 Participants	13 Participants n=24 Participants	13 Participants n=42 Participants	13 Participants n=42 Participants	89 Participants n=42 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	1 Participants n=4 Participants	1 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	1 Participants n=24 Participants	2 Participants n=42 Participants	1 Participants n=42 Participants	6 Participants n=42 Participants
Age, Continuous	46.7 years STANDARD_DEVIATION 4.3 • n=5 Participants	43.7 years STANDARD_DEVIATION 16.9 • n=7 Participants	50.7 years STANDARD_DEVIATION 7.6 • n=5 Participants	52.2 years STANDARD_DEVIATION 10.8 • n=4 Participants	48.3 years STANDARD_DEVIATION 17.6 • n=21 Participants	41.2 years STANDARD_DEVIATION 14 • n=8 Participants	41.3 years STANDARD_DEVIATION 14.5 • n=8 Participants	50.9 years STANDARD_DEVIATION 11.4 • n=24 Participants	46.3 years STANDARD_DEVIATION 17.2 • n=42 Participants	46.7 years STANDARD_DEVIATION 10.8 • n=42 Participants	46.6 years STANDARD_DEVIATION 13.4 • n=42 Participants
Sex: Female, Male Female	3 Participants n=5 Participants	3 Participants n=7 Participants	4 Participants n=5 Participants	2 Participants n=4 Participants	3 Participants n=21 Participants	2 Participants n=8 Participants	7 Participants n=8 Participants	8 Participants n=24 Participants	3 Participants n=42 Participants	4 Participants n=42 Participants	39 Participants n=42 Participants
Sex: Female, Male Male	3 Participants n=5 Participants	3 Participants n=7 Participants	2 Participants n=5 Participants	4 Participants n=4 Participants	4 Participants n=21 Participants	4 Participants n=8 Participants	8 Participants n=8 Participants	6 Participants n=24 Participants	12 Participants n=42 Participants	10 Participants n=42 Participants	56 Participants n=42 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	0 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	1 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	2 Participants n=42 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	6 Participants n=5 Participants	5 Participants n=7 Participants	6 Participants n=5 Participants	6 Participants n=4 Participants	7 Participants n=21 Participants	5 Participants n=8 Participants	14 Participants n=8 Participants	14 Participants n=24 Participants	14 Participants n=42 Participants	14 Participants n=42 Participants	91 Participants n=42 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	1 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	1 Participants n=42 Participants	0 Participants n=42 Participants	2 Participants n=42 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	1 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=42 Participants
Race (NIH/OMB) Asian	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	1 Participants n=24 Participants	0 Participants n=42 Participants	2 Participants n=42 Participants	3 Participants n=42 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	1 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=42 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	1 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	1 Participants n=24 Participants	1 Participants n=42 Participants	0 Participants n=42 Participants	3 Participants n=42 Participants
Race (NIH/OMB) White	6 Participants n=5 Participants	5 Participants n=7 Participants	6 Participants n=5 Participants	6 Participants n=4 Participants	6 Participants n=21 Participants	6 Participants n=8 Participants	14 Participants n=8 Participants	12 Participants n=24 Participants	12 Participants n=42 Participants	12 Participants n=42 Participants	85 Participants n=42 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	1 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	2 Participants n=42 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants
Region of Enrollment Canada	0 participants n=5 Participants	1 participants n=7 Participants	2 participants n=5 Participants	0 participants n=4 Participants	0 participants n=21 Participants	1 participants n=8 Participants	1 participants n=8 Participants	3 participants n=24 Participants	6 participants n=42 Participants	5 participants n=42 Participants	19 participants n=42 Participants
Region of Enrollment United States	6 participants n=5 Participants	5 participants n=7 Participants	4 participants n=5 Participants	6 participants n=4 Participants	7 participants n=21 Participants	5 participants n=8 Participants	9 participants n=8 Participants	7 participants n=24 Participants	6 participants n=42 Participants	8 participants n=42 Participants	63 participants n=42 Participants
Region of Enrollment Spain	0 participants n=5 Participants	0 participants n=7 Participants	0 participants n=5 Participants	0 participants n=4 Participants	0 participants n=21 Participants	0 participants n=8 Participants	5 participants n=8 Participants	4 participants n=24 Participants	3 participants n=42 Participants	1 participants n=42 Participants	13 participants n=42 Participants

PRIMARY outcome

Timeframe: From initiation of treatment to Day 106 for Part 1 and Day 190 for Part 2

Population: The safety set population is all participants that received at least one dose of ACE-083 or placebo during the study.

The number of participants that had a least one Treatment Emergent Adverse Event for the duration of each of the respective study parts.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=6 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=6 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg n=7 Participants ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg n=6 Participants ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) n=15 Participants Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) n=15 Participants Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Safety and Tolerability (Incidence of Adverse Events)	6 Participants	6 Participants	5 Participants	6 Participants	7 Participants	6 Participants	12 Participants	14 Participants	13 Participants	14 Participants

PRIMARY outcome

Timeframe: From initiation of treatment to Day 106 for Part 1 and Day 190 for Part 2

Population: The safety set population is all participants that received at least one dose of ACE-083 or placebo during the study.

The number of participants that had a least one Treatment Emergent Adverse Event with CTCAE Grade 3 or Higher for the duration of each of the respective study parts.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=6 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=6 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg n=7 Participants ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg n=6 Participants ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) n=15 Participants Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) n=15 Participants Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Safety and Tolerability (Severity of Adverse Events, Grade 3 or Higher).	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	1 Participants	1 Participants

PRIMARY outcome

Timeframe: From initiation of treatment to Day 106 for Part 1 and Day 190 for Part 2

Population: The safety set population is all participants that received at least one dose of ACE-083 or placebo during the study.

The number of participants that had a least one Treatment Emergent Adverse Event that led to dose interruption, dose reduction and/or drug withdrawn.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=6 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=6 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg n=7 Participants ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg n=6 Participants ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) n=15 Participants Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) n=15 Participants Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg n=14 Participants Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Safety and Tolerability (Severity of Adverse Events- Dose Interruption, Reduction and/or Drug Withdrawal) Dose interruption	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants
Safety and Tolerability (Severity of Adverse Events- Dose Interruption, Reduction and/or Drug Withdrawal) Dose reduction	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants
Safety and Tolerability (Severity of Adverse Events- Dose Interruption, Reduction and/or Drug Withdrawal) Drug Withdrawal	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	1 Participants

PRIMARY outcome

Timeframe: Time Frame: From initiation of treatment to Study Visit Day 190

Population: The Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Total Muscle Volume (TMV)of the treated muscle in Patients with FSHD administered ACE-083 or placebo During Part 2 (randomized, controlled portion) from Baseline to Day 190. Total Muscle volume was measured by Magnetic Resonance Imaging (MRI). MRI was performed bilaterally on the tibialis anterior and the biceps brachii on Day 1, Day Day 43, Day 106, and Day 190. Baseline and Day 190 total muscle volume, means and standard deviations are reported.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=14 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=13 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=14 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=14 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Total Muscle Volume (TMV) of the Treated Muscle in Patients With FSHD Administered ACE-083 or Placebo During Part 2 (Randomized, Controlled Portion) Baseline Total Muscle Volume (TMV)	79708.77 mm3 Standard Deviation 4507.67	85159.90 mm3 Standard Deviation 22382.20	104788.87 mm3 Standard Deviation 58681.86	89133.23 mm3 Standard Deviation 48264.27	—	—	—	—	—	—
Total Muscle Volume (TMV) of the Treated Muscle in Patients With FSHD Administered ACE-083 or Placebo During Part 2 (Randomized, Controlled Portion) Day 190 Total Muscle Volume (TMV)	81761.70 mm3 Standard Deviation 43533.71	95739.04 mm3 Standard Deviation 20689.98	109489.17 mm3 Standard Deviation 56130.61	102131.94 mm3 Standard Deviation 54608.84	—	—	—	—	—	—

PRIMARY outcome

Timeframe: Time Frame: From initiation of treatment to Study Visit Day 190

Population: The Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Percent Change of Total Muscle Volume (TMV)of the treated muscle in Patients with FSHD administered ACE-083 or placebo During Part 2 (randomized, controlled portion) from Baseline to Day 190. Total Muscle volume was measured by Magnetic Resonance Imaging (MRI). MRI was performed bilaterally on the tibialis anterior and the biceps brachii on Day 1, Day Day 43, Day 106, and Day 190. Percent Change from Baseline to Day 190 total muscle volume, mean and standard deviation is reported.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=14 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=13 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=14 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=14 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Percent Change of Total Muscle Volume (TMV) of the Treated Muscle in Patients With FSHD Administered ACE-083 or Placebo During Part 2 (Randomized, Controlled Portion)	5.46 percent change Standard Deviation 7.32	14.20 percent change Standard Deviation 10.72	1.07 percent change Standard Deviation 8.08	20.41 percent change Standard Deviation 16.64	—	—	—	—	—	—

SECONDARY outcome

Timeframe: Time Frame: From initiation of treatment to Study Visit Day 106

Population: The Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Percent Change in Total Muscle Volume (TMV) in muscle in patients with FSHD administered ACE-083 During 1 (open-label, dose-escalation portion) from Baseline to Day 106. Total Muscle volume was measured by Magnetic Resonance Imaging (MRI). MRI was performed bilaterally on the tibialis anterior and the biceps brachii on Day 1, Day Day 43, and Day 106, change from Baseline and Day 106 reported.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=6 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=6 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=6 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg n=6 Participants ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg n=6 Participants ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Percent Change in Total Muscle Volume (TMV) in Muscle in Patients With FSHD Administered ACE-083 During Part 1 (Open-label, Dose-escalation Portion)	8.1 percent change Standard Error 3.5	18.3 percent change Standard Error 3.7	19.7 percent change Standard Error 2.8	8.2 percent change Standard Error 6.0	17.1 percent change Standard Error 7.8	16.2 percent change Standard Error 4.7	—	—	—	—

SECONDARY outcome

Timeframe: Time Frame: From initiation of treatment to Study Visit Day 190

Population: The Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Absolute change in Fat Fraction (FF) of the muscle in patients with FSHD administered ACE-083 or Placebo During Part 2 (randomized, controlled portion) from Baseline to Day 190. Absolute change in intramuscular fat fraction in the tibialis anterior and biceps brachii were measured by Magnetic Resonance Imaging (MRI). MRI was performed bilaterally on the tibialis anterior and the biceps brachii on Day 1, Day Day 43, Day 106, and Day 190, change from Baseline and Day 190 reported.

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=14 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=13 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg n=14 Participants ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg n=14 Participants ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Absolute Change in Fat Fraction (FF) of the Muscle in Patients With FSHD Administered ACE-083 or Placebo During Part 2 (Randomized, Controlled Portion)	-0.32 Percent change Standard Error 0.888	-3.05 Percent change Standard Error 0.946	1.03 Percent change Standard Error 0.955	-0.22 Percent change Standard Error 0.978	—	—	—	—	—	—

SECONDARY outcome

Timeframe: From initiation of treatment (Study Day 1) to Study Visit Day 190

Population: Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Percent change from baseline in function of Tibialis Anterior during Part 2 assessed by: 6-minute walk test, 10 meter walk/run and 4-stair climb (ascend)

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=14 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=13 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Percent Change From Baseline in Function of Tibialis Anterior, Part 2 (Randomized, Controlled Portion) D190 6MWD from baseline	8.56 percent change Standard Error 2.764	3.28 percent change Standard Error 2.937	—	—	—	—	—	—	—	—
Percent Change From Baseline in Function of Tibialis Anterior, Part 2 (Randomized, Controlled Portion) D190 time to complete 10mW/R from baseline	-8.59 percent change Standard Error 3.351	-3.90 percent change Standard Error 3.585	—	—	—	—	—	—	—	—
Percent Change From Baseline in Function of Tibialis Anterior, Part 2 (Randomized, Controlled Portion) D190 4-stair ascend time from baseline	-5.20 percent change Standard Error 4.065	-4.75 percent change Standard Error 4.318	—	—	—	—	—	—	—	—

SECONDARY outcome

Timeframe: From initiation of treatment (Study Day 1) to Study Visit Day 190

Population: Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Elbow flexion strength measured by hand-held dynamometry (quantitative muscle testing), maximum voluntary isometric contraction (MVIC).

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=14 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=12 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Percent Change From Baseline in Strength of Biceps Brachii, Part 2, Randomized-controlled	-3.54 percent change Standard Error 10	32.58 percent change Standard Error 10.44	—	—	—	—	—	—	—	—

SECONDARY outcome

Timeframe: From initiation of treatment (Study Day 1) to Study Visit Day 190

Population: Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

Percent Change from Baseline in Performance of the Upper Limb (PUL) Mid-Level Elbow Dimension, Part 2, Randomized-controlled, PUL from baseline to end of treatment (Day 190). The Performance of the Upper Limb is an assessment specifically designed for patients with Duchenne muscular dystrophy. The measures used in this study was a subset of the assessment. PUL was assessment by measures of high-level of movement (lifting weights of 50g, 200g, 500g and 1000g at shoulder height and above shoulder height) and mid-level movement by performing tasks with and without weights: hand to mouth with and without weights (50, 200g), hand to table, moving weights on table (100g, 200g, 500g and 1000g), lift light and heavy cans, stack light and heavy cans, remove lid from container, tearing paper).

Outcome measures

Outcome measures
Measure	ACE-083 (Part 1, Cohort 1a) Tibialis Anterior (TA) 150 mg n=14 Participants ACE-083 150 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2a) Tibialis Anterior (TA) 200 mg n=14 Participants ACE-083 200 mg TA unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein.	ACE-083 (Part 1, Cohort 3a) Tibialis Anterior (TA) 200 mg ACE-083 200 mg TA bilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 1b) Biceps Brachii (BB) 150 mg ACE-083 150 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 2b) Biceps Brachii (BB) 200 mg ACE-083 200 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	ACE-083 (Part 1, Cohort 3b) Biceps Brachii (BB) 240 mg ACE-083 240 mg BB unilaterally, once every 3 weeks for up to 5 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Tibialis Anterior (TA) Double-Blind, Placebo-Controlled Placebo-TA bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Tibialis Anterior (TA) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg TA bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein	Placebo (Part 2, DB-PC) Biceps Brachii (BB) Double-Blind, Placebo-Controlled Placebo- BB bilaterally, once every 3 weeks for up to 9 doses. Drug: Placebo Normal saline	ACE-083 (Part 2, DB-PC) Biceps Brachii (BB) 240 mg Double-Blind, Placebo-Controlled ACE-083 240 mg BB bilaterally, once every 3 weeks for up to 9 doses. Drug: ACE-083 Recombinant fusion protein
Percent Change From Baseline in Performance of the Upper Limb (PUL) Mid-Level Elbow Dimension, Part 2, Randomized-controlled	-1.19 percent change Standard Error 1.16	1.70 percent change Standard Error 1.17	—	—	—	—	—	—	—	—

SECONDARY outcome

Timeframe: Time Frame: From initiation of treatment (Study Day 1) to Study Visit Day 190

Population: The Per Protocol Set: All patients enrolled/randomized in the study who received at least one dose of the study drug (includes placebo) with no major protocol violations.

The facioscapulohumeral muscular dystrophy-health index (FSHD-HI) is a disease-specific patient-reported outcome (PRO) tool assessed by health-related quality of life and disease burden. The FSHD-HI questionnaire was designed to measure both overall FSHD health-related quality-of-life and 14 separate subdomains designed and based on patient interviews to measure total FSHD health-related quality-of-life, including both motor impairment and the social and emotional impact of FSHD. The 116 questions are combined into a total score, the score is transformed onto a percentage scale; with a range of 0-100, with 100 representing maximal disability, and lower scores representing decreasing disability, 0 representing no disability. The mean and standard deviation for baseline and day 190 are reported as is the absolute change from baseline to Day 190 during the randomized controlled portion of Part 2.