Burosumab for Fibroblast Growth Factor-23 Mediated Hypophosphatemia in Fibrous Dysplasia

• ClinicalTrials.gov Identifier: NCT05509595
• Recruitment Status: Active, not recruiting
• First Posted: August 22, 2022
• Last Update Posted: March 19, 2024
• Sponsor: National Institute of Dental and Craniofacial Research (NIDCR)
• Information provided by (Responsible Party): National Institutes of Health Clinical Center (CC) ( National Institute of Dental and Craniofacial Research (NIDCR) )

Study Description

Brief Summary:

Background:

Fibrous dysplasia (FD) is a disorder that affects bone growth. Affected bone tissue is weakened, and people with FD are prone to deformities, fractures, and other problems. People with FD may also have low blood phosphate levels. This can make bones even weaker. Better treatments are needed.

Objective:

To test a study drug (burosumab) in people with FD who have low blood phosphate levels.

Eligibility:

People aged 1 year or older who have FD and low blood phosphate levels.

Design:

Participants will visit the NIH 3 times in 48 weeks. Each visit will last 5 to 7 days.

Participants will self-inject burosumab under the skin in their belly, upper arm, or thigh. They (or a caregiver) will do this at home 1 or 2 times a month. They will be trained in person on how to inject the drug. Home injections will be guided via telehealth.

During NIH visits, participants will have a physical exam with blood and urine tests. They will have x-rays of different parts of their body. They will have a radioactive tracer injected into their vein; then they will have a bone scan. They will have tests to assess their strength, walking, and movement. They will complete questionnaires about their pain, mobility, and fatigue levels.

Adult participants may have bone biopsies. These will be done under anesthesia with sedation. Small samples of FD-affected bone will be removed for study.

Between NIH visits, participants will go to a local laboratory for blood and urine tests.

Child participants will have an additional follow-up visit 2 weeks after the final NIH visit.

Condition or disease	Intervention/treatment	Phase
Fibrous Dysplasia Of Bone	Drug: Burosumab	Phase 2

Detailed Description:

Study Description:

This will be a phase 2, open-label, single-arm study to evaluate the safety and efficacy of burosumab to normalize serum phosphate levels in subjects with fibrous dysplasia (FD) and fibroblast growth factor 23 (FGF23)-mediated hypophosphatemia.

Objectives:

Primary Objective:

-Evaluate the efficacy of burosumab to normalize serum phosphate levels in subjects with FD and FGF23-mediated hypophosphatemia at 48 weeks.

Secondary Objectives:

• Evaluate the efficacy of burosumab to normalize serum phosphate levels in subjects with FD and FGF23-mediated hypophosphatemia at 24 weeks.
• Evaluate the safety and tolerability of burosumab in patients with FD.
• Evaluate the effect of burosumab on increasing serum phosphate and additional mineral markers.
• Evaluate the impact of burosumab on FD lesion activity.
• Evaluate the effect of burosumab on functional parameters.
• Evaluate the effect of burosumab on pain and health-related quality of life.

Endpoints:

Primary Endpoint:

-The proportion of subjects achieving serum phosphate levels within the target range (Z-score -1 to +2) at Week 48.

Secondary Endpoints:

• Proportion of subjects achieving serum phosphate levels within the target range (Z-score -1 to +2) at Week 24.
• Adverse events and clinical safety laboratory tests for up to 4 weeks after the final burosumab dose (48 weeks for adult subjects, 50 weeks for pediatric subjects).
• Change and percent change from baseline to post-baseline visits in serum phosphate, serum 1,25(OH)2D, ratio of renal tubular maximum reabsorption rate of phosphate to glomerular filtration rate (TmP/GFR).
• Change in FD lesion activity using 18F-NaF PET/CT total lesion activity from baseline to 48 weeks
• Change and percent change in serum bone turnover markers, including procollagen 1 N-terminal propeptide (P1NP), beta crosslaps C-telopeptides (CTX), osteocalcin, and bone-specific alkaline phosphatase from baseline to 48 weeks.
• Change in FD lesion histology and cell proliferation as assessed by minimally invasive bone biopsies from baseline to 48 weeks (adults with capacity to consent only) from baseline to 48 weeks
• Skeletal changes assessed on skeletal survey at baseline and 48 weeks

• Change from baseline to 48 weeks in:

  • Muscle strength
  • Range-of-motion
  • Walking speed (9-minute walk)

Change from baseline to 48 weeks in patient reported outcomes measures:

• SF36: adults
• SF10: children
• PROMIS Pain Intensity: Pediatric and Parent Proxy version 1.0, Adult version 2.0
• PROMIS Pain Interference: Pediatric and Parent Proxy v 2.0, Adult v 1.1
• PROMIS Mobility: Pediatric and Parent Proxy version 2.0, Adult Mobility Lower Extremity v 1.0
• PROMIS Fatigue: Pediatric and Parent Proxy v 2.0, Adult FACIT 13a v1.0
• Activities of Daily Living Questions: adults and children

Study Design

• Study Type: Interventional (Clinical Trial)
• Estimated Enrollment: 15 participants
• Allocation: N/A
• Intervention Model: Single Group Assignment
• Masking: None (Open Label)
• Primary Purpose: Treatment
• Official Title: A Phase 2 Study of Burosumab for Fibroblast Growth Factor-23 Mediated Hypophosphatemia in Fibrous Dysplasia
• Actual Study Start Date: December 7, 2022
• Estimated Primary Completion Date: September 30, 2030
• Estimated Study Completion Date: September 30, 2030

Arms and Interventions

Arm	Intervention/treatment
Experimental: Treatment; Patients receiving treatment	Drug: Burosumab; Human recombinant monoclonal antibody to fibroblast growth factor-23 (FGF23)

Outcome Measures

Primary Outcome Measures :

1. The proportion of subjects achieving serum phosphate levels within the target range (Z-score -1 to +2) at Week 48 [ Time Frame: 48 weeks ]
   Serum phosphate is the primary driver of skeletal complications in patients with FGF23-mediated hypophosphatemia and has been correlated with poor clinical outcomes in patients with FD.

Secondary Outcome Measures :

1. Change and percent change from baseline to post-baseline visits in serum phosphate, serum 1,25(OH)2D, ratio of renal tubular maximum reabsorption rate of phosphate to glomerular filtration rate (TmP/GFR). [ Time Frame: 48 weeks ]
   Safety endpoint for monitoring metabolic impact of burosumab in patients with FD.
2. Change in functional parameters: - Muscle strength - Range-of-motion - Walking speed (9-minute walk) [ Time Frame: 48 weeks ]
   Outcome measures that reflect activities of daily living
3. Change in FD lesion histology and cell proliferation as assessed by minimally invasive bone biopsies from baseline to 48 weeks (adults with capacity to consent only) from baseline to 48 weeks [ Time Frame: 48 weeks ]
   Safety endpoints to determine if burosumab impacts metabolic activity of FD lesions, which are a benign neoplastic process
4. Change from baseline to 48 weeks in patient reported outcomes measures: SF36, SF10, Brief Fatigue Inventory [ Time Frame: 48 weeks ]
   Outcome measures to determine pain and health-related quality of life
5. Proportion of subjects achieving serum phosphate levels within the target range (Z-score -1 to +2) at Week 24. [ Time Frame: 24 weeks ]
   Serum phosphate is the primary driver of skeletal complications in patients with FGF23-mediated hypophosphatemia and has been correlated with poor clinical outcomes in patients with FD.
6. Change and percent change in serum bone turnover markers, including procollagen 1 N-terminal propeptide (P1NP), beta crosslaps C-telopeptides (CTX), osteocalcin, and bone-specific alkaline phosphatase from baseline to 48 weeks. [ Time Frame: 48 weeks ]
   Safety endpoints to determine if burosumab impacts metabolic activity of FD lesions, which are a benign neoplastic process
7. Adverse events and clinical safety laboratory tests for up to 4 weeks after the final burosumab dose [ Time Frame: 48 weeks (adults), 50 weeks (children) ]
   Safety endpoints for expected and unexpected adverse events
8. Change in FD lesion activity using 18F-NaF PET/CT total lesion activity [ Time Frame: 48 weeks ]
   Safety endpoints to determine if burosumab impacts metabolic activity of FD lesions, which are a benign neoplastic process
9. Skeletal changes assessed on skeletal survey at baseline and 48 weeks [ Time Frame: 48 weeks ]
   Safety endpoints to determine if burosumab impacts metabolic activity of FD lesions, which are a benign neoplastic process

Eligibility Criteria

• Ages Eligible for Study: 1 Year to 99 Years (Child, Adult, Older Adult)
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: No

Criteria

• INCLUSION CRITERIA:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

• Confirmed diagnosis of fibrous dysplasia
• Serum phosphate <10th percentile for age and sex, AND intact serum FGF23 >=30 pg/mL
• Age >=1 year
• Provision of signed and dated informed consent/assent form
• Stated willingness of subject or Legally Authorized Representative (LAR) to comply with all study procedures and availability for the duration of the study

• For females of reproductive potential: agreement to use highly effective contraception for during study participation. Highly effective contraception methods include:

  • Total abstinence (when this is in line with the preferred and usual lifestyle of the participant). Periodic abstinence (e.g., calendar, ovulation, symptothermal, postovulation methods) and withdrawal are not acceptable methods of contraception
  • Female sterilization (have had surgical bilateral oophorectomy with or without hysterectomy) or tubal ligation at least six weeks before taking study treatment.
  • Male sterilization (at least 6 months prior to screening). For female participants on the study the vasectomized male partner should be the sole partner for that participant.

  • Combination of the following (a+b or a+c, or b+c):

    • Use of oral, injected or implanted hormonal methods of contraception or other forms of hormonal contraception that have comparable efficacy (failure rate <1%), for example hormone vaginal ring or transdermal hormone contraception
    • Placement of an intrauterine device (IUD) or intrauterine system (IUS)
    • Barrier methods of contraception: Condom or Occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/vaginal suppository
• For males of reproductive potential: use of condoms or other methods described above to ensure effective contraception with partner
• Minimum body weight of 7.5 kilograms

EXCLUSION CRITERIA:

An individual who meets any of the following criteria will be excluded from participation in this study:

• Pregnancy or lactation
• Known allergic reactions to burosumab or drug component
• Treatment with another investigational drug within 30 days of screening
• Treatment with burosumab within 30 days of screening
• Have any condition which in the opinion of the PI could present a concern for subject safety or difficulty with data interpretation
• Severe renal impairment or end stage renal disease, defined as: pediatric patients with estimated glomerular filtration rate (eGFR) 15 mL/min/1.73m2 to 29 mL/min/1.73m2 or end stage renal disease (eGFR < 15 mL/min/1.73m2), adult patients with creatinine clearance (CLcr) 15 mL/min to 29 mL/min or end stage renal disease (CLcr < 15 mL/min)

Contacts and Locations

Locations

United States, Maryland

National Institutes of Health Clinical Center

Bethesda, Maryland, United States, 20892

Sponsors and Collaborators

National Institute of Dental and Craniofacial Research (NIDCR)

Investigators

• Principal Investigator: Alison M Boyce, M.D.; National Institute of Dental and Craniofacial Research (NIDCR)

More Information

Additional Information:

NIH Clinical Center Detailed Web Page 

• Responsible Party: National Institute of Dental and Craniofacial Research (NIDCR)
• ClinicalTrials.gov Identifier: NCT05509595
• Other Study ID Numbers: 10000798; 000798-D
• First Posted: August 22, 2022
• Last Update Posted: March 19, 2024
• Last Verified: March 15, 2024

Individual Participant Data (IPD) Sharing Statement:

• Plan to Share IPD: Undecided
• Plan Description: .The study team anticipates that all IPD that underlie results in a publication will be made available on reasonable request. The specifics of the timing and review process are in development.

• Studies a U.S. FDA-regulated Drug Product: Yes
• Studies a U.S. FDA-regulated Device Product: No

Keywords provided by National Institutes of Health Clinical Center (CC) ( National Institute of Dental and Craniofacial Research (NIDCR) ):

McCune-Albright Syndrome; Rickets; Osteomalacia; Metabolic Bone Disorders

Additional relevant MeSH terms:

Fibrous Dysplasia of Bone; Hypophosphatemia; Phosphorus Metabolism Disorders; Metabolic Diseases; Osteochondrodysplasias; Bone Diseases, Developmental; Bone Diseases; Musculoskeletal Diseases