Adults 18 to 60, any sex, with Fibrodysplasia Ossificans Progressiva. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Period 1: Number of Participants With Treatment-emergent Adverse Events (TEAEs) and Serious TEAEsPrimary· Up to Week 28
Treatment-emergent adverse events (TEAEs) are adverse events not present at baseline or represent the exacerbation of a pre-existing condition during the on-treatment period. A serious TEAE was defined as any untoward medical occurrence that resulted in any of following outcomes not present at baseline or represent the exacerbation of a pre-existing condition during the on-treatment period: death, life-threatening, required initial/prolonged in-participant hospitalization, persistent/significant disability/incapacity, congenital anomaly/birth defect/considered as medically important event. Num
Participants with at least one TEAE
Group
Value
95% CI
Placebo
24
REGN2477 10 mg/kg Q4W
20
Participants with at least one serious TEAE
Group
Value
95% CI
Placebo
2
REGN2477 10 mg/kg Q4W
4
Period 1: Number of Participants With TEAEs by SeverityPrimary· Up to Week 28
Severity of TEAEs were graded as follows: Mild: Does not interfere in a significant manner with the participant's normal functioning level. It may be an annoyance. Prescription drugs are not ordinarily needed for relief of symptoms but may be given because of personality of the participants. Moderate: Produces some impairment of functioning but is not hazardous to health. It was uncomfortable or an embarrassment. Treatment for symptom may be needed. Severe: Produces significant impairment of functioning or incapacitation and was a definite hazard to the participant's health. Treatment for symp
Group
Value
95% CI
Placebo
9
REGN2477 10 mg/kg Q4W
7
Placebo
12
REGN2477 10 mg/kg Q4W
10
Placebo
3
REGN2477 10 mg/kg Q4W
3
Period 1: Time-Weighted Average (Standardized Area Under the Curve [AUC]) of the Percent Change From Baseline in Total Lesion Activity by Fluorine-18-labeled Sodium Fluoride (18^F-NaF) Positron Emission Tomography (PET) at Week 28 (AHO)Primary· Baseline and Week 28
18\^F-NaF PET is used to assess lesion and disease activity. Time-weighted average (standardized area under the curve \[AUC\]) of the percent change from baseline in total lesion activity by 18\^F-NaF PET up to Week 28 in AHO analysis set is reported.
Group
Value
95% CI
Placebo
16.6
± 9.11
REGN2477 10 mg/kg Q4W
-8.1
± 9.93
Period 1: Percent Change From Baseline in the Total Volume of HO Lesions as Assessed by Computed Tomography (CT) at Week 28 (AHO)Primary· Week 28
CT is a diagnostic imaging test used to create detailed images of internal organs, bones, soft tissue, and blood vessels. CT scan acquired contemporaneously to the PET scan. Percent change from baseline in the total volume of HO lesions as assessed by CT during Period 1 at Week 28 is reported.
Group
Value
95% CI
Placebo
32.0
± 18.66
REGN2477 10 mg/kg Q4W
7.1
± 20.43
Period 2: Number of New HO Lesions as Assessed by CT at Week 56 Relative to Week 28 Scan (AHO COVID-19 mITT)Primary· Week 28, Week 56
CT is a diagnostic imaging test used to create detailed images of internal organs, bones, soft tissue, and blood vessels. CT scan acquired contemporaneously to the PET scan. HO detectable by CT that developed after baseline are referred to as "new HO lesions." Number of new HO lesions as assessed by CT at Week 56 relative to Week 28 scan is reported.
Group
Value
95% CI
Placebo/REGN2477 10 mg/kg Q4W
0
Period 1: Time-weighted Average (Standardized AUC) of the Percent Change From Baseline in Total Lesion Activity Assessed by 18^F-NaF PET at Week 28 (AHOC)Primary· Week 28
18\^F-NaF PET is used to assess lesion and disease activity. Time-weighted average (Standardized AUC) of the percent change from baseline in total lesion activity as assessed by 18\^F-NaF PET in Active HO Classic ACVR1 Mutation (AHOC) analysis set up to Week 28 is reported.
Group
Value
95% CI
Placebo
17.6
± 9.73
REGN2477 10 mg/kg Q4W
-8.0
± 10.14
Period 1: Percent Change From Baseline in the Total Volume of HO Lesions as Assessed by CT at Week 28 (AHOC)Primary· Week 28
CT is a diagnostic imaging test used to create detailed images of internal organs, bones, soft tissue, and blood vessels. CT scan acquired contemporaneously to the PET scan. Percent change from baseline in the total volume of HO lesions was assessed by CT at Week 28 in AHOC analysis set is reported.
Group
Value
95% CI
Placebo
34.9
± 19.90
REGN2477 10 mg/kg Q4W
7.0
± 20.87
Period 1: Time-weighted Average (Standardized AUC) of the Change From Baseline in Daily Pain Due to Fibrodysplasia Ossificans Progressiva (FOP) Assessed by Daily Numeric Rating Scale (NRS) at Week 28 (AHO)Secondary· Week 28
The pain NRS is a patient reported outcome (PRO) used by participants to rate their pain associated with FOP. Participants were asked to rate their pain on a scale that ranges from "0" (no pain) to "10" (worst possible pain), where the highest score indicated worst outcome. Time-weighted average (Standardized AUC) of the change from baseline in daily pain due to FOP assessed by daily NRS at Week 28 in AHO analysis set is reported.
Group
Value
95% CI
Placebo
-0.17
± 0.205
REGN2477 10 mg/kg Q4W
-0.51
± 0.231
Period 1: Time-weighted Average (Standardized AUC) of the Change From Baseline in Daily Pain Due to FOP, Assessed by Daily NRS at Week 28 (AHOC)Secondary· Week 28
The pain NRS is a PRO used by participants to rate their pain associated with FOP. Participants were asked to rate their pain on a scale that ranges from "0" (no pain) to "10" (worst possible pain), where the highest score indicated worst outcome. Time-Weighted average (standardized AUC) of the change from baseline in daily pain due to FOP assessed by daily NRS at Week 28 in AHOC analysis set is reported.
Group
Value
95% CI
Placebo
-0.12
± 0.221
REGN2477 10 mg/kg Q4W
-0.48
± 0.237
Period 1: Percent Change From Baseline in 18^F-NaF SUVmax of Individual Active HO Site(s) Assessed by 18^F-NaF PET at Week 8 (AHOC)Secondary· Week 8
Standardized uptake value max (SUVmax) was a measurement of the maximum radiopharmaceutical uptake within the volume of interest. Relative accuracy of a particular radiotracer in a particular tissue is determined by expressing the absolute accuracy (obtained in the primary outcome measure) in terms of percent difference between SUVmax values obtained from PET/CT. Percent Change in 18\^F-NaF SUVmax of Individual Active HO Site(s) assessed by 18\^F-NaF PET in AHOC analysis set is reported.
Group
Value
95% CI
Placebo
-6.7
± 28.79
REGN2477 10 mg/kg Q4W
-21.6
± 30.25
Period 1: Percent Change From Baseline in 18^F-NaF SUVmax of Individual Active HO Site(s) as Assessed by 18^F-NaFPET at Week 8 (AHO)Secondary· Week 8
Percent change in 18\^F-NaF SUVmax of individual active HO site(s) as assessed by 18\^F-NaF PET at Week 8 in AHO analysis set is reported.
Group
Value
95% CI
Placebo
-7.9
± 28.80
REGN2477 10 mg/kg Q4W
-21.6
± 30.25
Period 1: Change From Baseline in Number of HO Lesions as Assessed by 18^F-NaF PET at Week 28 (AHOC)Secondary· Week 28
Change from baseline in number of HO lesions was assessed by 18\^F-NaF PET at Week 28 in AHOC analysis set is reported.
Group
Value
95% CI
Placebo
-1.0
± 2.66
REGN2477 10 mg/kg Q4W
-2.3
± 2.24
Adverse events — posted to ClinicalTrials.gov
Time frame: From first dose of study drug to end of study.
Reporting threshold: 5%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
Placebo
Serious: 2/24 (8%)
Deaths: 0/24
REGN2477 10 mg/kg Q4W
Serious: 4/20 (20%)
Deaths: 0/20
Placebo/REGN2477 10 mg/kg Q4W
Serious: 6/24 (25%)
Deaths: 2/24
REGN2477/REGN2477 10 mg/kg Q4W
Serious: 7/19 (37%)
Deaths: 3/19
Serious adverse events (23 terms)
Reaction
System
Placebo
REGN2477 10 mg/kg Q4W
Placebo/REGN2477 10 mg/kg …
REGN2477/REGN2477 10 mg/kg…
Gastroenteritis
Infections and infestations
—
—
—
—
Pneumonia
Infections and infestations
—
—
—
—
Sepsis
Infections and infestations
—
—
—
—
Urinary tract infection
Infections and infestations
—
—
—
—
Abscess
Infections and infestations
—
—
—
—
Abscess limb
Infections and infestations
—
—
—
—
Gastroenteritis viral
Infections and infestations
—
—
—
—
Perineal abscess
Infections and infestations
—
—
—
—
Perirectal abscess
Infections and infestations
—
—
—
—
Respiratory tract infection viral
Infections and infestations
—
—
—
—
Subcutaneous abscess
Infections and infestations
—
—
—
—
Intestinal obstruction
Gastrointestinal disorders
—
—
—
—
Crohn's disease
Gastrointestinal disorders
—
—
—
—
Epistaxis
Respiratory, thoracic and mediastinal disorders
—
—
—
—
Acute respiratory failure
Respiratory, thoracic and mediastinal disorders
—
—
—
—
Pneumonia aspiration
Respiratory, thoracic and mediastinal disorders
—
—
—
—
Pyrexia
General disorders
—
—
—
—
Head injury
Injury, poisoning and procedural complications
—
—
—
—
Skull fracture
Injury, poisoning and procedural complications
—
—
—
—
Splenic rupture
Injury, poisoning and procedural complications
—
—
—
—
Joint swelling
Musculoskeletal and connective tissue disorders
—
—
—
—
Cerebrovascular accident
Nervous system disorders
—
—
—
—
Renal colic
Renal and urinary disorders
—
—
—
—
Other adverse events (225 terms — click to expand)
This is a three period study design consisting of a 6-month, randomized, double-blind placebo-controlled treatment (period 1) followed by a 6-month, open-label treatment (period 2) and a follow-up treatment period (period 3).
Primary safety objective of the study is to assess the safety and tolerability of REGN2477 in male and female patients with fibrodysplasia ossificans progressiva (FOP).
Primary efficacy objective of the study is to assess the effect of REGN2477 versus placebo on the change from baseline in heterotopic ossification (HO) in patients with FOP, as determined by 18-NaF uptake in HO lesions by positron emission tomography (PET) and in total volume of HO lesions by computed tomography (CT).
Key Secondary objectives are:
* To compare the effect of REGN2477 versus placebo on pain due to FOP, as measured by the area under the curve (AUC) for pain based on daily pain numeric rating scale (NRS) scores
* To assess the effect of REGN2477 versus placebo on the change from baseline in HO, as determined by the number of new HO lesions identified by 18F-NaF PET or by CT
* To assess the effect of REGN2477 versus placebo on the change from baseline in 18F-NaF standardized uptake value maximum (SUVmax) of individual active HO site(s) by PET
* To assess the effect of REGN2477, between week 28 and week 56, on the number, activity, and volume of HO lesions identified by 18F-NaF PET or by CT in patients who switch from placebo to REGN2477 at week 28 versus the same patients between baseline and week 28
* To assess the effect of REGN2477 versus placebo on the change from baseline in biochemical markers of bone formation
* To characterize the concentrations of total activin A at baseline and over time following the first dose of study drug
* To characterize the concentration-time profile (pharmacokinetics \[PK\]) of REGN2477 in patients with FOP
* To assess the immunogenicity of REGN2477
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT02943239 — Study of Safety, Tolerability, and Pharmacokinetics of REGN2477 Alone and in Combination With REGN1033 in Healthy Postme
· Phase 1
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Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by Regeneron Pharmaceuticals
Last refreshed: 2 December 2022
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT03188666.