Evaluation of Safety, Tolerability, and Changes in Biomarker and Clinical Outcome Assessments of Losmapimod for FSHD1 With Extension (FSHD)

An Open-Label Pilot Study of Losmapimod to Evaluate the Safety, Tolerability, and Changes in Biomarker and Clinical Outcome Assessments in Subjects With Facioscapulohumeral Muscular Dystrophy 1 (FSHD1) With Extension

This clinical trial is a study to evaluate the safety, tolerability, and changes in biomarker and clinical outcome assessments of Losmapimod for patients with Facioscapulohumeral Muscular Dystrophy 1 (FSHD1) with an open-label extension.

Study Overview

• Status: Terminated
• Conditions: Facioscapulohumeral Muscular Dystrophy 1
• Intervention / Treatment: Drug: Losmapimod

Detailed Description

This study is a single-centre, open-label pilot study that will investigate the safety, tolerability, pharmacokinetics (PK), and target engagement during long-term dosing with losmapimod tablets in adult subjects with FSHD1. Subjects will be evaluated during an 8- week pre-treatment period (Visits 1 through 3) to establish pre-treatment baseline assessments. Subjects will then be treated with losmapimod for approximately 1 year (Visits 4 through 9) and assessed at relatively regular intervals for change from pre-treatment assessments. All subjects will undergo two muscle biopsies; one at baseline, pre-treatment (Visit 4, Week 8 ± 1 week) and the second on-treatment muscle biopsy approximately 4 or 8 weeks later (Visit 5, Week 14 ± 2 weeks). Up to 8 subjects will have an on-treatment biopsy at 4 weeks and up to 8 subjects will have the on-treatment biopsy at 8 weeks.

Only subjects who participated in and competed all study procedures in the OLS Study treatment period (Week 60) will be eligible to participate in the open-label extension study.

The extension of this study will enable continued investigation of the safety and tolerability of long-term dosing with losmapimod tablets in adult subjects with FSHD1. During the extension study, subjects will receive 15 mg of losmapimod by mouth twice daily for a total of 30 mg by mouth daily. All subjects will attend clinic visits approximately every 24 weeks and have a safety phone call 12 weeks between in-person clinic visits until 90 days after commercial drug is available post regulatory approval or until study termination.

The primary endpoint of the main study is to evaluate the safety and tolerability of long-term dosing of losmapimod tablets in subjects with FSHD1. Secondary endpoints include assessment of target engagement of losmapimod in blood and skeletal muscle and repeated dose pharmacokinetics in subjects with FSHD1 over long-term dosing.

The extension will continue investigation of efficacy with assessment of skeletal muscle by ultrasound as well as the safety, tolerability, pharmacokinetics (PK), and exploration of efficacy measures including whole body skeletal muscle MRI and selected clinical outcome assessments during long- term dosing with losmapimod tablets in adult subjects with FSHD1. Secondary endpoints include assessment of efficacy as evaluated by whole body skeletal muscle MRI parameters, safety and tolerability of long-term dosing, target engagement of losmapimod in blood and skeletal muscle and repeated dose pharmacokinetics in subjects with FSHD1 over long-term dosing.

• Study Type: Interventional
• Enrollment (Actual): 14
• Phase: Phase 2

Contacts and Locations

Study Locations

• Netherlands
  • Nijmegen, Netherlands, 9101
    • Radboud University Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• FSHD1 subjects age 18-65 years.
• Subject will sign and date an informed consent form (ICF).
• Confirmed diagnosis of FSHD1 with 1 to 9 repeats via assessment of the size of the D4Z4 array on chromosome 4. Genetic confirmation must be obtained prior to the screening MRI and baseline muscle biopsy; genetic confirmation can come from previous testing if verified with appropriate documentation.
• Must be willing and able to comply with scheduled visits, treatment plan, study restrictions, laboratory tests, contraceptive guidelines, scheduled needle muscle biopsies, and other study procedures.
• Both male and female subjects must be willing to practice an approved method of birth control.
• Clinical Severity Score between 2 and 4 on Ricci's Scale (scale range is from 0 to 5). Subjects that use a wheelchair or walker for any activity are not permitted to enroll in the study.
• Commitment to complete the 2 visits for skeletal muscle needle biopsy and all visits for whole-body MRI.
• Able to complete the RWS, TUG, and FSHD PROs (FSHD-RODS and FSHD-HI) at the screening visit.
• Must have an MRI-eligible muscle for biopsy as determined by the central reader.
• Subject must complete the main study through the Week 60 visit in order to participate in the open-label extension study.

Exclusion Criteria:

• History of any illness or any clinical condition that, in the opinion of the investigator, might confound the results of the study or pose an additional risk in administering study drug to the subject. This may include, but is not limited to, history of relevant drug or food allergies; history of cardiovascular or central nervous system disease; history or presence of clinically significant pathology; clinically significant history of mental disease; and history of cancer, except for squamous cell skin cancer, basal cell skin cancer, and Stage 0 cervical carcinoma in situ (all 3 with no recurrence for the last 5 years).
• Subject has a known or clinically suspected infection with human immunodeficiency virus or hepatitis B or C viruses.
• Subject has current clinically significant liver (alanine aminotransferase > 2X upper limit of normal or total bilirubin >1.5 X upper limit of normal) or kidney (GFR < 30 mL/min/1.73m2) dysfunction.
• Subject screens positive for hepatitis B surface antigen, hepatitis C virus (HCV) antibody, or antibodies against human immunodeficiency viruses 1 and 2 (HIV 1/HIV 2 antibodies).
• Subject has any condition possibly affecting drug absorption (eg, gastrectomy, cholecystectomy, or other gastrointestinal tract surgery, except appendectomy).
• Subject has a standard 12-lead ECG demonstrating QT interval by Fredericia (QTcF) >450 msec for male subjects and QTcF >470 msec for female subjects at Screening. If QTcF exceeds 450 msec for males or 470 msec for females, the ECG will be repeated 2 more times, and the average of the 3 QTcF values will be used to determine the subject's eligibility.
• Subject has a history of cardiac dysrhythmias requiring anti-arrhythmia treatment(s); or history or evidence of abnormal ECGs that, in the opinion of the investigator or Medical Monitor, would preclude the subject's participation in the study.
• Male subject has a female partner who is planning to become pregnant during the study or within 90 days after the last study drug dose.
• Subject has donated blood (of approximately 1 pint [500 mL] or more) or has had any significant loss of blood within 90 days before the first study drug dose, as determined by the investigator.
• Vaccination with a live attenuated vaccine within 6 weeks of randomisation.
• Subject has a history of alcohol, analgesic/opioid, and/or illicit drug abuse as defined by the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, in the last 6 months before screening, or a positive test for drugs of abuse at screening.
• Subject has participated in a clinical trial in which they have received an investigational product within the following time period prior to enrolment in the current study: 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product (whichever was longer).
• For subjects that are on drug(s) or supplements that may affect muscle function as determined by the treating physician or included in the list of drugs presented in Section 15: subjects must be on a stable dose of that drug(s) or supplement for at least 3 months prior to enrollment in the study and remain on that stable dose for the duration of the study (list of drugs presented in Section 15). Changes to the dose or treatment discontinuation during the study can only be done for strict medical reasons by the treating physician with clear documentation and notification to the Sponsor.
• Subject has a history of sensitivity to any of the study medications or components thereof, or a history of drug or other allergy that, in the opinion of the investigator or Medical Monitor, contraindicated their participation.
• Female subject is pregnant as determined by positive urine Human Chorionic Gonadotropin (HCG) test at Screening or prior to dosing.
• Female subject is lactating.
• Subject is unwilling or unable to follow the procedures outlined in the protocol.
• Subject has any contraindication for MRI (including severe claustrophobia and any shrapnel or metal implants in the body that are not MRI compatible).
• Subject was mentally or legally incapacitated up to 2 years prior to enrollment.
• Subject has abnormal laboratory results indicative of any significant medical disease that, in the opinion of the investigator or the medical monitor, would preclude the subject's participation in the study.
• Subject, or close relative of the subject, is the investigator or a subinvestigator, research assistant, pharmacist, study coordinator, or other staff directly involved with the conduct of the study at that site.
• Subject has taken any anticoagulants for at least 1 month and anti-platelet agents for at least 1 week before each muscle biopsy.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Treatment; FSHD1 subjects with genetic confirmation will receive 15 mg of losmapimod twice daily given by mouth; for a total of 30 mg daily until 90 days after commercial drug is available post regulatory approval or study termination.

Drug: Losmapimod; The main study includes a treatment period of approximately one year. Subjects will receive 15 mg of losmapimod twice daily by mouth; for a total of 30 mg daily. The study drug should be taken with food and the date and time of each dose taken recorded in the subject diary. Only subjects who participated in and completed all procedures for the main study (Week 60) will be eligible to participate in the extension. For the extension, subjects will receive 15 mg of losmapimod by mouth twice daily for a total of 30 mg by mouth daily. Participation will continue until 90 days after commercial drug is available post regulatory approval or study termination.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Participants Reporting Treatment Emergent Adverse Events (TEAEs) and Serious TEAEs	An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of a study intervention, whether or not considered related to the study intervention. A TEAE is an AE that begins on or after the first dose of study drug and before the stop of study drug + 7 days or begins before the first dose of study drug and worsens on or after the first dose of study drug and before the stop of study drug + 7 days. A Serious adverse event (SAE) is any untoward medical occurrence that, at any dose results in death, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent disability/incapacity, is a congenital anomaly/birth defect or any other situation according to medical or scientific judgment.	Up to 68 Weeks
Number of Participants With Clinically Significant Changes in Chemistry Parameters	Blood samples were collected for the analysis of chemistry parameters: Glucose, sodium, potassium, calcium, inorganic phosphate, total protein, albumin, blood urea nitrogen, creatinine, uric acid, total bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase, lactate dehydrogenase and creatine phosphokinase.	Up to 68 Weeks
Number of Participants With Clinically Significant Changes in Hematology Parameters	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	Up to 68 Weeks
Number of Participants With Clinically Significant Changes in Serum Coagulation Parameters	Blood samples were collected for the analysis of Serum coagulation parameters: International normalized ratio, prothrombin time, activated partial thromboplastin time and fibrinogen.	Up to 68 Weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percent Change From Baseline in the Ratio of Phosphorylated HSP27 (pHSP27) /Total HSP27 in Sorbitol-stimulated Whole Blood	Phosphorylated HSP27 in peripheral whole blood with ex-vivo sorbitol stimulation and in skeletal muscle (without sorbitol stimulation) was measured at specified time points. The pre-treatment value was considered as Baseline for change from Baseline calculations. The geometric mean for fold percent change from Baseline (and 95% confidence interval) in pHSP27/total HSP27 was calculated. Percent change from baseline = 100*(exp(mean of change from baseline on the log-transformed scale) - 1).	Baseline and at Week 44
Percent Change From Baseline in Ratio of pHSP27/Total HSP27 in Muscle	Phosphorylated HSP27 in skeletal muscle (without sorbitol stimulation) was measured at specified time points. The pre-treatment value was considered as Baseline for change from Baseline calculations. The geometric mean for fold percent change from Baseline (and 95% confidence interval) in pHSP27/total HSP27 was calculated. Percent change from baseline = 100*(exp(mean of change from baseline on the log-transformed scale) - 1).	Baseline and at Week 8
Plasma Concentration of Losmapimod	Blood samples were collected to measure the plasma concentration of losmapimod at specified timepoints.	Post-dose at Baseline, Week 4, Week 8, Week 20, Week 32, Week 44, and Week 56
Muscle Concentration of Losmapimod	Muscle biopsies were collected to measure the concentration of losmapimod at specified timepoints.	Post dose at Baseline, Week 4, Week 8 and Week 44

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Muscle Disease Transcripts	To evaluate the change from baseline in inflammatory, immune, apoptotic, and muscle disease transcripts in muscle biopsy and circulating proteins in plasma and serum.	Week 40
DUX4 Activity in Skeletal Muscle	Change from baseline in DUX4 activity by quantitative polymerase chain reaction (qPCR) of skeletal muscle using a subset of DUX4 regulated gene transcripts.	Week 40
Muscle Lean Tissue Volume	Change from baseline in skeletal muscle lean tissue volume as measured by whole body magnetic resonance imaging (MRI).	Week 204
Muscle Tissue Replacement by Fat	Change from baseline in skeletal muscle tissue replacement by fat as measured by whole body magnetic resonance imaging (MRI).	Week 204
Muscle Ultrasound	Ultrasound will be used to evaluate the echogenicity of specified muscles.	Week 52
Reachable Workspace (RWS)	Subjects are seated in front of a 3D camera and asked to perform a standardized upper extremity movement protocol under the supervision of a study clinical evaluator with and without weights to detect an individual's range of motion that reflects individual shoulder and proximal arm upper extremity function.	Week 204
Timed Up and Go (TUG)	Subjects are timed as they start from a seated or laying position, rise to a standing position, walk a total of 6 meters and then return to either a seated or laying position to determine ambulatory function.	Week 204
Motor Function Measure (MFM) Domain 1	The MFM domain 1 is a validated evaluator administered functional measure for neuromuscular disorders, with 13 items related to standing and transfers and assesses the severity of the motor deficit.	Week 204
Quantitative Manual Dynamometry	Muscle strength will be assessed by quantitative dynamometry with hand-held devices (manual). Force will be measured on digital myometer, in KG-force.	Week 204
FSHD Rasch-built Overall Disability Scale (RODS)	The FSHD-RODS is a patient-reported, linearly weighted scale that precisely measures activities of daily living (ADLs) and participation in subjects with FSHD using 50 items based on the Rasch model.	Week 204
Real World Mobility Assessments	Each subject's activity will be monitored in the outpatient setting intermittently from the signing of the informed consent form (ICF) to the end of the study. Wearable activity monitoring devices will be provided to each subject at the start of the study. One device is placed on 1 arm, and 1 device goes on 1 leg.	Week 204
FSHD Health Index (FSHD-HI)	The FSHD-HI is a 15-domain questionnaire 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. 116 questions are combined into a total score, the score is transformed onto a percentage scale, with 100 representing maximal disability, and lower scores representing decreasing disability.	Week 204
Patients' Global Impression of Change (PGIC)	The PGIC is a single question that assesses on a scale of 1-7 if there has been an improvement, decline or no change in clinical status.	Week 204
6 Minute Walk Test (6-MWT)	Change from the pre-treatment period in the distance a subject is able to walk will be measured in time.	Week 204
Spirometry - Respiratory Function	Change in lung ventilatory function as measured by forced vital capacity and forced expiratory volume in 1 second using bedside spirometry.	Week 204

Collaborators and Investigators

• Sponsor: Fulcrum Therapeutics
• Investigators: Study Director: Marie-Helene Jouvin, MD, Fulcrum Therapeutics

Publications and helpful links

General Publications

• Barbour AM, Sarov-Blat L, Cai G, Fossler MJ, Sprecher DL, Graggaber J, McGeoch AT, Maison J, Cheriyan J. Safety, tolerability, pharmacokinetics and pharmacodynamics of losmapimod following a single intravenous or oral dose in healthy volunteers. Br J Clin Pharmacol. 2013 Jul;76(1):99-106. doi: 10.1111/bcp.12063.
• Cheriyan J, Webb AJ, Sarov-Blat L, Elkhawad M, Wallace SM, Maki-Petaja KM, Collier DJ, Morgan J, Fang Z, Willette RN, Lepore JJ, Cockcroft JR, Sprecher DL, Wilkinson IB. Inhibition of p38 mitogen-activated protein kinase improves nitric oxide-mediated vasodilatation and reduces inflammation in hypercholesterolemia. Circulation. 2011 Feb 8;123(5):515-23. doi: 10.1161/CIRCULATIONAHA.110.971986. Epub 2011 Jan 24.
• Han JJ, Kurillo G, Abresch RT, de Bie E, Nicorici A, Bajcsy R. Reachable workspace in facioscapulohumeral muscular dystrophy (FSHD) by Kinect. Muscle Nerve. 2015 Feb;51(2):168-75. doi: 10.1002/mus.24287. Epub 2014 Nov 19.
• Statland JM, Tawil R. Risk of functional impairment in Facioscapulohumeral muscular dystrophy. Muscle Nerve. 2014 Apr;49(4):520-7. doi: 10.1002/mus.23949. Epub 2014 Feb 10.
• de Greef JC, Frants RR, van der Maarel SM. Epigenetic mechanisms of facioscapulohumeral muscular dystrophy. Mutat Res. 2008 Dec 1;647(1-2):94-102. doi: 10.1016/j.mrfmmm.2008.07.011. Epub 2008 Aug 3.

Study record dates

Study Major Dates

• Study Start (Actual): August 23, 2019
• Primary Completion (Actual): October 31, 2024
• Study Completion (Actual): October 31, 2024

Study Registration Dates

• First Submitted: June 25, 2019
• First Submitted That Met QC Criteria: June 28, 2019
• First Posted (Actual): July 1, 2019

Study Record Updates

• Last Update Posted (Estimated): December 2, 2025
• Last Update Submitted That Met QC Criteria: November 18, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: Musculoskeletal Diseases; Neuromuscular Diseases; FSHD, FSHD1; Muscular Dystrophies; Facioscapulohumeral Muscular Disorders; Atrophic Muscular Diseases
• Additional Relevant MeSH Terms: Nervous System Diseases; Muscular Diseases; Genetic Diseases, Inborn; Muscular Disorders, Atrophic; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Muscular Dystrophies; Musculoskeletal Diseases; Neuromuscular Diseases; 6-(5-((cyclopropylamino)carbonyl)-3-fluoro-2-methylphenyl)-N-(2,2-dimethylprpyl)-3-pyridinecarboxamide
• Other Study ID Numbers: FIS-001-2019

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No