Trial Outcomes & Findings for Efficacy and Safety of Losmapimod in Treating Subjects With Facioscapulohumeral Muscular Dystrophy (FSHD) With Open-Label Extension (OLE) (NCT NCT04264442)

NCT ID: NCT04264442

Last Updated: 2025-09-30

Results Overview

A TEAE is an adverse event that begins on or after the first dose of study drug and on or before the stop of study drug plus 7 days or begins before the first dose of study drug and worsens on or after the first dose of study drug and on or before the stop of study drug plus 7 days. An adverse event with completely missing onset and end dates was considered as TEAE. An adverse event with missing onset date but the end date is on or after the first dose of study drug and before the stop of study drug plus 7 days was considered a TEAE.

Recruitment status

TERMINATED

Study phase

PHASE2

Target enrollment

76 participants

Primary outcome timeframe

Up to 57 months

Results posted on

2025-09-30

Participant Flow

Participants who completed either 24 or 48 weeks in the placebo-controlled treatment period of the parent study were eligible to enroll in the Open-Label Extension (OLE) phase. A total 76 participants entered the OLE) phase and received at least 1 dose of losmapimod. Of those, 39 were previously in the losmapimod group and 37 in the placebo group during the double-blind treatment period of study (NCT04003974) and met eligibility criteria for continued treatment.

Participants were analysed according to their original treatment assignment and their entry point into the OLE: Losmapimod 15 mg BID / Losmapimod 15 mg BID (from Week 24 or Week 48) and Placebo BID / Losmapimod 15 mg BID (from Week 24 or Week 48).

Participant milestones

Participant milestones
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Overall Study
STARTED
76
Overall Study
COMPLETED
29
Overall Study
NOT COMPLETED
47

Reasons for withdrawal

Reasons for withdrawal
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Overall Study
Lack of Efficacy
6
Overall Study
Lost to Follow-up
2
Overall Study
Sponsor Decision
23
Overall Study
Withdrawal by Subject
11
Overall Study
Study Termination
5

Baseline Characteristics

Efficacy and Safety of Losmapimod in Treating Subjects With Facioscapulohumeral Muscular Dystrophy (FSHD) With Open-Label Extension (OLE)

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Age, Continuous
46.2 Years
STANDARD_DEVIATION 12.43 • n=5 Participants
Sex: Female, Male
Female
25 Participants
n=5 Participants
Sex: Female, Male
Male
51 Participants
n=5 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
3 Participants
n=5 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
69 Participants
n=5 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
4 Participants
n=5 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants
n=5 Participants
Race (NIH/OMB)
Asian
5 Participants
n=5 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants
n=5 Participants
Race (NIH/OMB)
Black or African American
0 Participants
n=5 Participants
Race (NIH/OMB)
White
66 Participants
n=5 Participants
Race (NIH/OMB)
More than one race
1 Participants
n=5 Participants
Race (NIH/OMB)
Unknown or Not Reported
4 Participants
n=5 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

A TEAE is an adverse event that begins on or after the first dose of study drug and on or before the stop of study drug plus 7 days or begins before the first dose of study drug and worsens on or after the first dose of study drug and on or before the stop of study drug plus 7 days. An adverse event with completely missing onset and end dates was considered as TEAE. An adverse event with missing onset date but the end date is on or after the first dose of study drug and before the stop of study drug plus 7 days was considered a TEAE.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants Reporting Serious Treatment Emergent Adverse Events (Serious TEAEs) and TEAEs
Any serious TEAE
7 Participants
Number of Participants Reporting Serious Treatment Emergent Adverse Events (Serious TEAEs) and TEAEs
Any TEAE
71 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

Blood samples were collected for the analysis of chemistry parameters: Glucose, sodium, potassium, calcium, inorganic phosphate, total protein, albumin, blood urea nitrogen, creatinine, total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase and creatine phosphokinase.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Chemistry Parameters
0 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set:

Blood samples were collected for the analysis of hematology parameters: hemoglobin (including mean corpuscular volume), mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, hematocrit, red blood cell count, total white blood cell count, platelet count. Differential blood counts, including basophils, eosinophils, neutrophils, lymphocytes, and monocytes

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Hematology Parameters
0 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

Blood samples were collected for the analysis of Serum coagulation parameters: International normalized ratio, prothrombin time, partial thromboplastin time.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Serum Coagulation Parameters
0 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

Urine samples were collected for the analysis of urinalysis parameters: Leucocytes, blood, nitrite, protein, urobilinogen, bilirubin, pH, specific gravity, ketones, glucose.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Urinalysis
0 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

Vital parameters including pulse rate, respiration rate, blood pressure, and temperature were measured in seated or recumbent for at least 5 minutes. Data for number of participants with abnormal clinically significant changes for vital signs have been presented.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Vital Parameters
0 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

Twelve-lead ECGs was performed after participants has been recumbent for at least 5 minutes.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Electrocardiogram (ECG) Parameters
0 Participants

PRIMARY outcome

Timeframe: Up to 57 months

Population: Open-Label Analysis Set.

Physical examinations included an evaluation of body systems, including but not limited to the following: skin; head, eyes, ears, nose, and throat; respiratory system; cardiovascular system; abdomen (liver, spleen); lymph nodes; neurological system; and musculoskeletal system.

Outcome measures

Outcome measures
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 Participants
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Number of Participants With Clinically Significant Changes in Physical Examinations
0 Participants

Adverse Events

Losmapimod 15 Milligrams (mg) Twice Daily (BID)

Serious events: 7 serious events
Other events: 71 other events
Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 participants at risk
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Cardiac disorders
Acute myocardial infarction
2.6%
2/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Cardiac disorders
Coronary artery disease
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
General disorders
Ulcer haemorrhage
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Immune system disorders
Anaphylactic reaction
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Musculoskeletal chest pain
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Neoplasms benign, malignant and unspecified (incl cysts and polyps)
Endometrial cancer
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Nervous system disorders
Syncope
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Vascular disorders
Labile blood pressure
1.3%
1/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.

Other adverse events

Other adverse events
Measure
Losmapimod 15 Milligrams (mg) Twice Daily (BID)
n=76 participants at risk
Participants will continue to receive Losmapimod 15 mg (2×7.5 mg tablets/dose) BID until 90 days after commercial drug is available post regulatory approval or until the study is discontinued by the Sponsor (up to 60 months).
Cardiac disorders
Palpitations
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Eye disorders
Dry eye
7.9%
6/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Gastrointestinal disorders
Diarrhoea
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Gastrointestinal disorders
Food poisoning
6.6%
5/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
General disorders
Fatigue
10.5%
8/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
General disorders
Pain
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Infections and infestations
Corona virus infection
48.7%
37/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Infections and infestations
Influenza
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Infections and infestations
Nasopharyngitis
19.7%
15/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Infections and infestations
Sinusitis
7.9%
6/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Infections and infestations
Urinary tract infection
10.5%
8/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Arthropod bite
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Contusion
14.5%
11/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Fall
36.8%
28/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Joint injury
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Ligament sprain
7.9%
6/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Skin abrasion
6.6%
5/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Injury, poisoning and procedural complications
Skin laceration
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Arthralgia
18.4%
14/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Back pain
7.9%
6/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Muscle spasms
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Musculoskeletal pain
7.9%
6/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Myalgia
11.8%
9/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Neck pain
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Musculoskeletal and connective tissue disorders
Pain in extremity
9.2%
7/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Nervous system disorders
Headache
11.8%
9/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Psychiatric disorders
Anxiety
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Psychiatric disorders
Insomnia
6.6%
5/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Renal and urinary disorders
Nephrolithiasis
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Respiratory, thoracic and mediastinal disorders
Cough
6.6%
5/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Respiratory, thoracic and mediastinal disorders
Oropharyngeal pain
6.6%
5/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Respiratory, thoracic and mediastinal disorders
Sleep apnoea syndrome
6.6%
5/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Skin and subcutaneous tissue disorders
Rash
5.3%
4/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.
Vascular disorders
Hypertension
9.2%
7/76 • Up to 57 months
Serious TEAEs and TEAEs were collected in Open-Label Analysis Set which comprised of all participants who completed 24 or 48 weeks of treatment in the placebo-controlled treatment period and received at least 1 dose of open-label losmapimod in the OLE.

Additional Information

Call Center

Fulcrum Therapeutics

Phone: 617-651-8853

Results disclosure agreements

  • Principal investigator is a sponsor employee
  • Publication restrictions are in place

Restriction type: OTHER