ClinicalTrials.gg
CompletedNCT03581591Updated Jan 18, 2020

Open Label Trial Assessing Safety and Efficacy of Burosumab (KRN23), in a Patient With ENS and Hypophosphatemic Rickets

A Phase 3 interventional study of Burosumab in Hypophosphatemia, Hypophosphatemic Rickets and Pain, Chronic, sponsored by Redwood Dermatology Sciences. Completed at 1 site in United States. Open to female participants aged Up to 18 Years. Per ClinicalTrials.gov, last updated 2020-01-18.

Primary conditionRickets, HypophosphatemicRegistry: HypophosphatemiaReclassifiedWhy we changed it
Registry
Hypophosphatemia — the first condition term the registry derived for this study.
ClinicalTrials.gg
Rickets, Hypophosphatemic
Why
  1. The study's listed conditions name Rickets, Hypophosphatemic, a narrower term within Hypophosphatemia.
Confidence
High: the new condition is named in the study's own listed conditions. Of 351 hand-checked studies reclassified this way, 68% were exactly right and 84% in the right disease family; the registry's first term was right for 5% (measured 2026-10-21). How we classify →
Wrong?
Tell us the study's main condition →

Sponsored by Redwood Dermatology Sciences · Phase 3, Interventional, and Treatment

From the registry’s dates

  • Primary completion was Dec 2019, 6 years 11 months ago, and no results have been posted to the registry.
Phase
Phase 3
Study type
Interventional
Enrollment
1
Allocation
Not applicable
Ages
Up to 18 Years
Sex
Female
01

Study summary

A 52 week, open label trial to assess the safety and efficacy of KRN23, an investigational antibody to FGF23, in a single pediatric patient with Epidermal Nevus Syndrome(ENS) and associated hypophosphatemic rickets

A 26 weeks extension to original study to monitor patient lab results for her safety.

Read the detailed description

1.1 Primary Objective

The effect of KRN23 treatment on normalizing age-adjusted serum phosphorous levels in a single pediatric patient with Epidermal Nevus Syndrome associated hypophosphatemic rickets

1.2 Secondary Objectives

  1. The PD profile of KRN23 as assessed by changes from baseline over time 1,25(OH)2D, iPTH, Serum Calcium, TRP and TmP/GFR (the ratio of renal tubular maximum phosphate reabsorption rate to glomerular filtration rate)
  2. Changes in underlying skeletal disease/rickets as assessed by standard radiographs utilizing the Radiographic Global Impression of Change (RGI-C) rating scales
  3. Effects of KRN23 on biochemical markers of bone turnover that reflect rickets severity, alkaline phosphatase (ALP)
  4. Walking ability as assessed by 6-Minute Walk Test (6MWT)
  5. Patient/parent-Reported Outcomes as assessed by PROMIS and FPS-R rating scales

1.3 Exploratory Objective

  1. Dual-energy X-ray absorptiometry (DXA)

1.4 Safety Objective Assess the safety of KRN23 administration in a single patient with ENS-associated hypophosphatemic rickets, based on adverse events (AEs), laboratory assessments, cardiac imaging and renal ultrasound.

02

Conditions studied

  • Hypophosphatemia
  • Hypophosphatemic Rickets
  • Pain, Chronic

Browse trials for

03

In context

Rickets, Hypophosphatemic Reclassified

10 studies on the registry are indexed under Rickets, Hypophosphatemic; none are open to participants now.

Browse Rickets, Hypophosphatemic studies →

Lead sponsor

This is the only study on the registry with Redwood Dermatology Sciences as lead sponsor.

Compared within Rickets, Hypophosphatemic, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Hypophosphatemia. The counts are of registry records indexed under each term, refreshed daily. How we classify →

04

Who can participate

Ages eligible
Up to 18 Years
Sexes eligible
Female
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. Patient has confirmed ENS by physician diagnosis
  2. Patient has confirmed FGF23 elevations in the context of low serum phosphorous \< 4.1 mg/dL
  3. Patient able to tolerate KRN23 treatment
  4. Have a corrected serum calcium level \< 10.8mg/dL
  5. Have an >60 ml/min
  6. Must be willing in the opinion of the investigator, to comply with study procedures and schedule
  7. Provide written by a parent after the study has been explained and prior to any research related procedures begin

Exclusion criteria

Exclusion Criteria:

  1. Concomitant use of active vitamin D (i.e calcitriol) and/or exogenous phosphate supplementation. Patient will be allowed OTC Vitamin D should levels drop below \<20 ng/ml
  2. The use or enrollment in studies using other therapies including other monoclonal antibodies
  3. Subject and their parent not willing or not able to give written
  4. In the Investigators opinion, the patient may not be able to meet all the requirements for study participation
  5. Patient has a history of to KRN23 that in the opinion of the investigator, places the patient at an increased risk of adverse effects
  6. Patient has a condition that in the opinion of the investigator could present a concern for subject safety or data interpretation.
Terms in these criteria, in plain language(5)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

GFR and eGFR (kidney filtering)

GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².

Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Excipients

The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.

05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrollment
1 participant (actual)

Study arms

  • Experimental
    Primary; open label

    Injection of Burosumab every two to three weeks based on Serum Phosphorus level of subject. Initial dose to be 0.3 mg/kg. Subsequent dosing will be titrated up or down depending on Serum Phosphorus level for that time period.

    Biological: Burosumab

Interventions

  • BiologicalBurosumab

    recombinant human IgG1 monoclonal antibody to fibroblast growth factor 23)

06

What researchers measure

Primary outcomes

  1. The effect of KRN23 treatment on normalizing age-adjusted serum phosphorous levels in a single pediatric patient with Epidermal Nevus Syndrome associated hypophosphatemic rickets

    Time frame: 18 months

07

Study locations

1 site
  • The Focus Center, PC
    Clinton, Utah 84015, United States
08

References and documents

Publications

  • Aono Y, Yamazaki Y, Yasutake J, Kawata T, Hasegawa H, Urakawa I, Fujita T, Wada M, Yamashita T, Fukumoto S, Shimada T. Therapeutic effects of anti-FGF23 antibodies in hypophosphatemic rickets/osteomalacia. J Bone Miner Res. 2009 Nov;24(11):1879-88. doi: 10.1359/jbmr.090509. PubMed 19419316 ↗
  • Aono Y, Hasegawa H, Yamazaki Y, Shimada T, Fujita T, Yamashita T, Fukumoto S. Anti-FGF-23 neutralizing antibodies ameliorate muscle weakness and decreased spontaneous movement of Hyp mice. J Bone Miner Res. 2011 Apr;26(4):803-10. doi: 10.1002/jbmr.275. PubMed 20939065 ↗
  • Carpenter TO, Imel EA, Ruppe MD, Weber TJ, Klausner MA, Wooddell MM, Kawakami T, Ito T, Zhang X, Humphrey J, Insogna KL, Peacock M. Randomized trial of the anti-FGF23 antibody KRN23 in X-linked hypophosphatemia. J Clin Invest. 2014 Apr;124(4):1587-97. doi: 10.1172/JCI72829. Epub 2014 Feb 24. PubMed 24569459 ↗
  • Lim YH, Ovejero D, Sugarman JS, Deklotz CM, Maruri A, Eichenfield LF, Kelley PK, Juppner H, Gottschalk M, Tifft CJ, Gafni RI, Boyce AM, Cowen EW, Bhattacharyya N, Guthrie LC, Gahl WA, Golas G, Loring EC, Overton JD, Mane SM, Lifton RP, Levy ML, Collins MT, Choate KA. Multilineage somatic activating mutations in HRAS and NRAS cause mosaic cutaneous and skeletal lesions, elevated FGF23 and hypophosphatemia. Hum Mol Genet. 2014 Jan 15;23(2):397-407. doi: 10.1093/hmg/ddt429. Epub 2013 Sep 4. PubMed 24006476 ↗
09

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Ran from Jan 2018 to primary completion in Dec 2019, 22 months.

How these figures are worked out, and which studies are left out of them.

Registered
Oct 27, 2017
First posted
Jul 10, 2018
StartActual
Jan 31, 2018
Primary completionActual
Dec 6, 2019
CompletionActual
Dec 6, 2019
Last update
Jan 18, 2020
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Jan 18, 2020, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT03581591
Lead sponsor
Redwood Dermatology Sciences
Responsible party
Sponsor
First posted
Jul 10, 2018
Start date
Jan 31, 2018
Primary completion
Dec 6, 2019
Completion
Dec 6, 2019
Last update
Jan 18, 2020

Study contacts

Jeffrey Sugarman, MD PhD
principal investigator · Redwood Dermatology Sciences

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Jan 2020. You cannot join it, but the record below documents what was studied.

Follow this study

Get an email when the registry record changes — status, dates, results — or when someone posts here.

Sign in to follow

Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.

Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Studies of the drug tested here: Burosumab

Start the discussion