NCT03993821 is a EARLY_PHASE1 clinical trial of Burosumab in Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS), sponsored by Laura Tosi.

Who is sponsoring NCT03993821?

NCT03993821 is sponsored by Laura Tosi.

What drugs are being tested in NCT03993821?

Interventions in NCT03993821: Burosumab.

Is NCT03993821 still recruiting?

NCT03993821 is currently status unknown. Last updated 4 March 2022.

Last reviewed 2022-03-04 · How we verify

NCT03993821

Name: Drug Landscape Pharmaceutical Database
Creator: Drug Landscape
Published: 2026-01-01
License: https://creativecommons.org/licenses/by/4.0/

An Open Label Trial to Assess the Safety and Efficacy of Burosumab in a Single Patient With Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS)

Status unknown EARLY_PHASE1 Last updated 4 March 2022

What this trial tests

EARLY_PHASE1 trial testing Burosumab in Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS) in 1 participant. Status unknown.

Timeline

1 July 2019

Primary endpoint
30 October 2022

1 March 2023

Quick facts

Lead sponsor	Laura Tosi
Phase	EARLY_PHASE1
Status	Status unknown
Study type	INTERVENTIONAL
Allocation	na
Design	single group
Masking	none
Primary purpose	treatment
Enrollment	1
Start date	1 July 2019
Primary completion	30 October 2022
Estimated completion	1 March 2023
Sites	1 location across United States

Drugs / interventions tested

Burosumab (BUROSUMAB) — full drug profile →

Conditions studied

Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS) — all drugs for Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS) →
Epidermal Nevus Syndrome — all drugs for Epidermal Nevus Syndrome →

Sponsor

Laura Tosi

Who can join

Eligibility, any sex, with Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS) or Epidermal Nevus Syndrome. Patients with the condition only — healthy volunteers not accepted.

What's being measured

Primary outcomes are the specific endpoints the trial is designed to prove or disprove.

Serum Phosphorus change
Time frame: 52 weeks
Change from baseline over 52 weeks in serum phosphorus with burosumab treatment.

Sponsor's own description

Burosumab (also known as the drug, Crysvita®) is a fully human immunoglobulin G1 (IgG1) monoclonal antibody (mAb) that binds to and inhibits the activity of fibroblast growth factor 23 (FGF23), leading to an increase in serum phosphorus levels. This drug is already approved for use in patients with X-linked hypophosphatemia (XLH), but not for Cutaneous Skeletal Hypophosphatemia Syndrome (CSHS). It is hypothesized that burosumab may provide clinical benefit to a patient with CSHS due to the common underlying feature in this patient and in patients with XLH - abnormally elevated FGF23 in the context of low age -adjusted serum phosphorous levels.

Publications & conference data

2 peer-reviewed publications reference this trial (live from Europe PMC):

Clinical Evidence for the Benefits of Burosumab Therapy for X-Linked Hypophosphatemia (XLH) and Other Conditions in Adults and Children.
Schindeler A, Biggin A, Munns CF. · · 2020 · cited 44× · PMID 32547492 · DOI 10.3389/fendo.2020.00338
Burosumab treatment in an adult with FGF23-mediated hypophosphatemia due to cutaneous skeletal hypophosphatemia syndrome.
Tosi LL, Rajah EN, Gillies AP, Kim M, et al · · 2026 · PMID 41907689 · DOI 10.1210/jendso/bvag040

Verify or expand the search:

Other trials of Burosumab

Trials testing the same drug.

NCT05509595 — Burosumab for Fibroblast Growth Factor-23 Mediated Hypophosphatemia in Fibrous Dysplasia · Phase 2 · completed
NCT05181839 — A Study to Describe the Lived Experience of XLH for Adolescents at End of Skeletal Growth · completed
NCT04695860 — Anti-FGF23 (Burosumab) in Adult Patients With XLH · Phase 3 · completed
NCT04188964 — Study to Assess the Safety, Tolerability, Pharmacokinetics and Efficacy of Burosumab in Patients Less Than 1 Year of Age · Phase 1, PHASE2 · completed
NCT03920072 — Study of the Anti-FGF23 Antibody, Burosumab, in Adults With XLH · Phase 3 · completed

Verify against primary sources

ClinicalTrials.gov — authoritative US registry record
WHO ICTRP — international registry index
EU Clinical Trials Register
Sponsor press releases (Google)

Data sources for this page

Trial protocol + status: ClinicalTrials.gov NCT03993821 (US National Library of Medicine, public domain)
Publications: Europe PMC API search by NCT ID, retrieved 9 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 Laura Tosi
Last refreshed: 4 March 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/NCT03993821.

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing