Study of Longitudinal Observation for Patient With X-linked Hypophosphatemic Rickets/Osteomalacia in Collaboration With Asian Partners (SUNFLOWER)

An International, Multicenter, Prospective, Longitudinal Observational Study for Patient With X-linked Hypophosphatemic Rickets/Osteomalacia

Through observation of patients with X-linked hypophosphatemic rickets/osteomalacia (XLH) for up to 10 years, the study intends to collect data that allow achievement of the following objectives:

1. To determine medical characteristics of the disease and the disease process
2. To determine physical and psychological burden on patients as well as economic burden
3. To assess the efficacy and safety of the treatment of the disease

Study Overview

• Status: Active, not recruiting
• Conditions: X-Linked Hypophosphatemia
• Intervention / Treatment: Other: no intervention

• Study Type: Observational
• Enrollment (Actual): 226

Contacts and Locations

Study Locations

• Japan
  • Osaka, Japan
    • Osaka University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

Patients with XLH independent of treatment regimen

Description

Inclusion Criteria:

• Patients must meet at least one of the following:

  1. Documented PHEX gene mutation
  2. Documented PHEX gene mutation in at least one family member with X-linked genetic relationship
  3. Documented FGF23 >30 pg/mL
• Typical clinical findings of rickets/osteomalacia
• Written informed consent obtained from patients aged >=18 years or from parents or legally acceptable representatives of patients aged <18 years

Exclusion Criteria:

• Participation in any clinical study (trial) at the time of informed consent
• Any patient whose participation in the study is considered inappropriate by the investigator or the subinvestigator

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
X-linked Hypophosphatemia (XLH); Hypophosphatemic Rickets/osteomalacia	Other: no intervention; no intervention

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Height	Height in centimeters	After enrollment, patients will be observed annually or every 2 years for up to 10 years.
The 6-Minutes Walking Test	The 6-Minutes Walking Test performed according to International Guidelines, will be measured as distance in meters.	After enrollment, patients will be observed annually for up to 10 years.
Timed Up and Go Test(TUGT)	The time required for each patient to do the TUGT will be recorded: Stand up from sitting in a chair, walk 3 meters, turn around, walk back, and sit down.	After enrollment, patients will be observed every 2 years for up to 10 years.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fracture	Incidence of fracture of all parts	10 years
Radiography	Radiography of the sites listed below will be performed. AP views of both knees, PA vies of both wrists, and both long legs. Sites with symptoms such as pain, sites of suspected fracture, and spine (cervical, thoracic and lumber).	After enrollment, patients will be observed annually or every 2 years for up to 10 years.
Nephrocalcinosis	The renal ultrasound will be performed and the presence and/or progression of nephrocalcinosis will be measured.	After enrollment, patients will be observed annually or every 2 years for up to 10 years.

Collaborators and Investigators

• Sponsor: Kyowa Kirin Co., Ltd.

Publications and helpful links

General Publications

• Kubota T, Fukumoto S, Cheong HI, Michigami T, Namba N, Ito N, Tokunaga S, Gibbs Y, Ozono K. Long-term outcomes for Asian patients with X-linked hypophosphataemia: rationale and design of the SUNFLOWER longitudinal, observational cohort study. BMJ Open. 2020 Jun 29;10(6):e036367. doi: 10.1136/bmjopen-2019-036367.
• Ito N, Kang HG, Michigami T, Namba N, Kubota T, Shintani A, Kawai R, Kabata D, Ishii H, Nishida Y, Fukumoto S, Ozono K. Prevalence of Comorbid Hyperparathyroidism and Its Association with Renal Dysfunction in Asian Patients with X-Linked Hypophosphatemic Rickets/Osteomalacia. Calcif Tissue Int. 2025 Mar 12;116(1):50. doi: 10.1007/s00223-025-01359-9.

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2018
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: November 6, 2018
• First Submitted That Met QC Criteria: November 16, 2018
• First Posted (Actual): November 19, 2018

Study Record Updates

• Last Update Posted (Estimated): September 5, 2025
• Last Update Submitted That Met QC Criteria: August 28, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Keywords: XLH
• Additional Relevant MeSH Terms: Urogenital Diseases; Bone Diseases; Musculoskeletal Diseases; Nutrition Disorders; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Metabolism, Inborn Errors; Genetic Diseases, Inborn; Metabolic Diseases; Bone Diseases, Metabolic; Phosphorus Metabolism Disorders; Avitaminosis; Deficiency Diseases; Malnutrition; Metal Metabolism, Inborn Errors; Rickets, Hypophosphatemic; Rickets; Hypophosphatemia, Familial; Renal Tubular Transport, Inborn Errors; Calcium Metabolism Disorders; Vitamin D Deficiency; Hypophosphatemia; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Nutritional and Metabolic Diseases; Familial Hypophosphatemic Rickets
• Other Study ID Numbers: SUNFLOWER; UMIN000031605 (Registry Identifier: UMIN-CTR)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No