X-linked HypophosphatemiaEarly Phase 1NCT03748966
Calcitriol Monotherapy for X-Linked Hypophosphatemia
A Early Phase 1 study testing Calcitriol in people with X-linked Hypophosphatemia and Hypophosphatemic Rickets, run by Massachusetts General Hospital at 1 site in United States.
Trial summary
Children and adults with XLH recruited will be treated with calcitriol alone (without phosphate supplementation) for one year, during which the calcitriol dose will be escalated during the first 3 months of therapy. Read more about this study
- Who is it for?
- Ages 3 to 70 years
- Conditions the study is for
- X-linked Hypophosphatemia, Hypophosphatemic Rickets, Hypophosphatemic Rickets, X-Linked Dominant
- What is being tested?
- Calcitriol
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 16 participants
- Where
- 1 siteUnited States
- Study dates
- 28 Mar 2019to 26 Feb 2026
- Phase
- Early Phase 1
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 3 to 70 years
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Who may be able to join
- Clinical diagnosis of XLH with family history excluding male-to-male transmission, or positive genotype for PHEX mutation
- Serum PTH levels less than 1.5x the upper limit of normal
- Serum calcium levels less than 10.0 mg/dl
- eGFR >= 60 mL/min/1.73m2
- 25(OH) vitamin D level >= 20 ng/dL
Who cannot join
- Known allergy to calcitriol
- Pregnancy or breast feeding
- Use of skeletally active agents such as bisphosphonates, teriparatide, SERMS, hormone replacement therapy and progesterone-only contraceptive agents (combination oral contraceptive use in premenopausal women is not an exclusion criterion).
- Unwilling or unable to stop therapy with calcitriol and phosphate therapy for two weeks prior to study
- Therapy with cinacalcet within the past two weeks
- Current use of growth hormone therapy
Show all 13Show fewer
- Use of diuretics or medications that alter renal handling of mineral ions.
- Use of glucocorticoids for more than 14 days in the past 12 months with the exception of inhaled agents.
- History of malignancy except basal and squamous cell carcinoma of the skin.
- Significant history of psychiatric disease per DSM-5.
- Substance use disorder per DSM-5.
- Significant cardiopulmonary disease (unstable CAD or stage D ACC/AHA heart failure).
- Absence of laboratory values for serum calcium, phosphate and creatinine in the 24 months prior to enrollment.
Trial locations and contacts
1 site in 1 country.
United States1 site
Massachusetts General Hospital
Boston, Massachusetts, 02114
About this study
Official title: Calcitriol Monotherapy for X-Linked Hypophosphatemia: Effects on Mineral Ions, Growth and Skeletal Parameters
Children and adults with XLH recruited will be treated with calcitriol alone (without phosphate supplementation) for one year, during which the calcitriol dose will be escalated during the first 3 months of therapy. The investigators hypothesize that treatment of adults and children with XLH alone will improve serum phosphate levels and skeletal mineralization without causing an increase in kidney calcifications. The study will also examine if calcitriol therapy will improve growth in children.
- Conditions
- X-linked Hypophosphatemia, Hypophosphatemic Rickets, Hypophosphatemic Rickets, X-Linked Dominant
- Being tested
- Calcitriol
- Keywords
- XLH, calcitriol, x-linked hypophosphatemia, rickets, 1,25 dihydroxyvitamin D, bone disorder, rare bone disease, vitamin D, hypophosphatemic rickets
- Medical subject headings
- Familial Hypophosphatemic Rickets, Rickets, Hypophosphatemic, Rickets, Bone Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CalcitriolDrug
Also called 1,25 dihydroxyvitamin D
Adults and children (age 3-17) with X-linked hypophosphatemia will be treated with calcitriol therapy without phosphate supplementation. Doses of calcitriol will be escalated and optimized in the first three months of the study. Calcitriol is an oral medication taken once a day.
| Study group | Role | What they receive |
|---|---|---|
| Adults with XLH | Experimental | Adults with X-linked hypophosphatemia will be treated with optimized doses of calcitriol (without phosphate supplementation) for one year Receives: Drug: Calcitriol |
| Children with XLH | Experimental | Children (age 3-17) with X-linked hypophosphatemia will be treated with optimized doses of calcitriol (without phosphate supplementation) for one year Receives: Drug: Calcitriol |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Serum Phosphate in Adults and Children With XLH Between Baseline and 12 Months
serum phosphate
Measured: baseline and 12 months
Change From Baseline in TmP/GFR in Adults and Children With XLH
a measure of kidney resorption of phosphate
Measured: baseline and 12 months
Rickets Score for Children With XLH
a score of rickets severity determined by reading x-rays of wrists and knees (10 point Thacher score with 0 being normal and 10 being severe)
Measured: baseline and 12 months
Change From Baseline in Nephrocalcinosis Grade
determine if there is change in amount of calcifications in the kidneys: graded from grade 0 (normal) to grade IV (stone formation, solitary focus of echos at the tip of the renal pyramid)
Measured: baseline and 12 months
Secondary outcomes (1)
Growth in Children With XLH
Z-score of growth (this is full name of variable)- number represents standard deviation above or below the known mean of the general population at the corresponding age. Z score that is positive is above the mean, negative is below the mean.
Measured: baseline and 12 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Nov 2018
- Study start28 Mar 2019
- Primary completion1 Mar 2025
- Study completion26 Feb 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for X-linked HypophosphatemiaStudies of the same condition, open and under way.
- More trials run by Massachusetts General HospitalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Model description
- Adults or children (age 3-17) with X-linked hypophosphatemia (XLH) will be enrolled the study. All research subjects will be treated with optimized doses of calcitriol alone (without phosphate supplementation) for one year.
- Masking
- None (open label)
- Enrolment
- 16 participants (actual)
Sponsor and investigators
- Lead sponsor
- Massachusetts General Hospital
- Sponsor type
- University, hospital or other
- Collaborators
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
- Responsible party
- Principal investigator, Eva Liu, Massachusetts General Hospital
- Investigators
- Eva Liu, MD, Principal investigator, Massachusetts General Hospital and Brigham and Women's Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03748966
- Sponsor's protocol ID
- 2016P001000
- Status last verified
- Mar 2026
- First submitted
- 19 Nov 2018
- Last updated
- 7 May 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Liu ES, Martins JS, Raimann A, Chae BT, Brooks DJ, Jorgetti V, Bouxsein ML, Demay MB. 1,25-Dihydroxyvitamin D Alone Improves Skeletal Growth, Microarchitecture, and Strength in a Murine Model of XLH, Despite Enhanced FGF23 Expression. J Bone Miner Res. 2016 May;31(5):929-39. doi: 10.1002/jbmr.2783. Epub 2016 Feb 2.
PubMed 26751835
Study at a glance
From the registry record, last updated by the sponsor on 7 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Calcitriol Monotherapy for X-Linked Hypophosphatemia: Effects on Mineral Ions, Growth and Skeletal Parameters
- ClinicalTrials.gov ID
- NCT03748966
- Acronym / sponsor ID
- 2016P001000
- Conditions
- X-linked Hypophosphatemia, Hypophosphatemic Rickets, Hypophosphatemic Rickets, X-Linked Dominant
- Keywords
- XLH, calcitriol, x-linked hypophosphatemia, rickets, 1,25 dihydroxyvitamin D, bone disorder, rare bone disease, vitamin D
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 16 participants (actual)
- Lead sponsor
- Massachusetts General HospitalUniversity, hospital or other
- Collaborators
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
- Study start
- 28 Mar 2019 (actual)
- Primary completion
- 1 Mar 2025 (actual)
- Study completion
- 26 Feb 2026 (actual)
- First posted
- 21 Nov 2018 (actual)
- Results
- Posted 7 May 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Children and adults with XLH recruited will be treated with calcitriol alone (without phosphate supplementation) for one year, during which the calcitriol dose will be escalated during the first 3 months of therapy. The investigators hypothesize that treatment of adults and children with XLH alone will improve serum phosphate levels and skeletal mineralization without causing an increase in kidney calcifications. The study will also examine if calcitriol therapy will improve growth in children.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- Adults or children (age 3-17) with X-linked hypophosphatemia (XLH) will be enrolled the study. All research subjects will be treated with optimized doses of calcitriol alone (without phosphate supplementation) for one year.
| Arm | Type | Receives |
|---|---|---|
| Adults with XLH | Experimental | Drug: CalcitriolAdults with X-linked hypophosphatemia will be treated with optimized doses of calcitriol (without phosphate supplementation) for one year |
| Children with XLH | Experimental | Drug: CalcitriolChildren (age 3-17) with X-linked hypophosphatemia will be treated with optimized doses of calcitriol (without phosphate supplementation) for one year |
Who may qualify
- Ages
- 3 to 70 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (5 listed)
- Clinical diagnosis of XLH with family history excluding male-to-male transmission, or positive genotype for PHEX mutation
- Serum PTH levels less than 1.5x the upper limit of normal
- Serum calcium levels less than 10.0 mg/dl
- eGFR >= 60 mL/min/1.73m2
- 25(OH) vitamin D level >= 20 ng/dL
Key exclusion criteria (13 listed)
- Known allergy to calcitriol
- Pregnancy or breast feeding
- Use of skeletally active agents such as bisphosphonates, teriparatide, SERMS, hormone replacement therapy and progesterone-only contraceptive agents (combination oral contraceptive use in premenopausal women is not an exclusion criterion).
- Unwilling or unable to stop therapy with calcitriol and phosphate therapy for two weeks prior to study
- Therapy with cinacalcet within the past two weeks
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| CalcitriolAlso: 1,25 dihydroxyvitamin DAdults and children (age 3-17) with X-linked hypophosphatemia will be treated with calcitriol therapy without phosphate supplementation. Doses of calcitriol will be escalated and optimized in the first three months of the study. Calcitriol is an oral medication taken once a day. | Drug | Adults with XLH, Children with XLH |
Primary outcome
Change in Serum Phosphate in Adults and Children With XLH Between Baseline and 12 Months
Time frame: baseline and 12 months
serum phosphate
Change From Baseline in TmP/GFR in Adults and Children With XLH
Time frame: baseline and 12 months
a measure of kidney resorption of phosphate
Rickets Score for Children With XLH
Time frame: baseline and 12 months
a score of rickets severity determined by reading x-rays of wrists and knees (10 point Thacher score with 0 being normal and 10 being severe)
Change From Baseline in Nephrocalcinosis Grade
Time frame: baseline and 12 months
determine if there is change in amount of calcifications in the kidneys: graded from grade 0 (normal) to grade IV (stone formation, solitary focus of echos at the tip of the renal pyramid)
1 secondary outcome
Growth in Children With XLH
Time frame: baseline and 12 months
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 May 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Background: PubMed 26751835Liu ES, Martins JS, Raimann A, Chae BT, Brooks DJ, Jorgetti V, Bouxsein ML, Demay MB. 1,25-Dihydroxyvitamin D Alone Improves Skeletal Growth, Microarchitecture, and Strength in a Murine Model of XLH, Despite Enhanced FGF23 Expression. J Bone Miner Res. 2016 May;31(5):929-39. doi: 10.1002/jbmr.2783. Epub 2016 Feb 2.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Eva Liu, MD principal investigator
Massachusetts General Hospital and Brigham and Women's Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing Calcitriol in people with X-linked Hypophosphatemia and Hypophosphatemic Rickets, run by Massachusetts General Hospital at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 7 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 7 May 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Serum Phosphate in Adults and Children With XLH Between Baseline and 12 Months (time frame: baseline and 12 months). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03748966, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 May 2026; AzTrials last refreshed its copy on 5 Nov 2026.