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Prader-Willi SyndromePhase 3NCT04697381

Study of the Efficacy and Safety of Somatropin in Japanese Participants With PWS

A Phase 3 study testing somatropin - GH naïve pediatric cohort, somatropin - GH treated cohort and somatropin - adult cohort in people with Prader-Willi Syndrome, run by Pfizer at 5 sites in Japan.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This is a multicenter, open label, multi cohort study to evaluate the efficacy and safety of somatropin in a cohort of Japanese participants with PWS. Read more about this study

Who is it for?
Ages 0 years and older
Conditions the study is for
Prader-Willi Syndrome
What is being tested?
somatropin - GH naïve pediatric cohort, somatropin - GH treated cohort and somatropin - adult cohort
Could I receive a placebo?
No, everyone receives an active treatment
How many people
33 participants
Where
5 sitesJapan
Study dates
9 Feb 2021to 15 Apr 2024
Phase
Phase 3
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 0 years and older
  • All sexes
  • No healthy volunteers
  • Child, Adult, Older adult

Who may be able to join

  • Male or female participants with documentation of genetically confirmed diagnosis of PWS.
  • No plan to initiate a new treatment that may affect the body composition, such as gonadal hormone replacement therapy.
  • Currently on appropriate diet and exercise programs and willing to continue throughout the study period at the discretion of the investigator.
  • Participants, and if required by local/site regulations their parent(s)/legal guardian(s) must be willing and able to comply with all scheduled visits, treatment plan, laboratory tests, lifestyle considerations, and other study procedures.
  • Evidence of a personally signed and dated ICD (and written assent where applicable based on age and country regulation) indicating that the participant or a legally acceptable representative/parent(s)/legal guardian has been informed of all pertinent aspects of the study. Refer to Appendix 1 for the detailed process of obtaining consent.
  • For inclusion of GH naïve pediatric cohort, participants must meet criteria 6 to 8:
Show all 16Show fewer
  • 18 years or younger.
  • Naïve to GH treatment.
  • Tanner stage 1 (for testes in males, for breasts in females).
  • For inclusion of GH treated pediatric cohort, participants must meet criteria 9 and 10:
  • Continued GH treatment for at least 2 years with stable dose for the last 6 months and being on GH at time of inclusion. The recent dose should be higher than 0.084 mg/kg/week.
  • Participants who are about to complete GH treatment for his/her short stature (eg, due to meeting the treatment stopping criteria defined as a height SDS more than -2.5 for Japanese adult standards).
  • For inclusion of adult cohort, participants must meet criteria 11 to 13:
  • 18 years of chronological age or older at Day 1 visit.
  • Off from GH treatment for at least 1 year.
  • Serum IGF-I level within +2 SDS, adjusted for age and sex.

Who cannot join

  • Participants with uncontrolled diabetes at the discretion of the investigator.
  • Participants with malignant tumors.
  • Participants with severe obesity or serious respiratory impairment.
  • Other medical or psychiatric condition including recent (within the past year) or active suicidal ideation/behavior or laboratory abnormality that may increase the risk of study participation or, in the investigator's judgment, make the participant inappropriate for the study.
  • Previous administration with an investigational drug within 30 days (or as determined by the local requirement) or 5 half- lives preceding the first dose of study intervention used in this study (whichever is longer).
  • Investigator site staff or Pfizer employees directly involved in the conduct of the study, site staff otherwise supervised by the investigator, and their respective family members.

Trial locations and contacts

5 sites in 1 country.

5 sites in 1 country

Japan5 sites

  • Hamamatsu University Hospital

    Hamamatsu, Shizuoka, 431-3192

  • Osaka Women's and Children's Hospital

    Izumi, Osaka, 594-1101

  • Dokkyo Medical University Saitama Medical Center

    Koshigaya, Saitama, 343-8555

  • National Center for Child Health and Development

    Setagaya-ku, Tokyo, 157-8535

  • Kanagawa Children's Medical Center

    Yokohama, Kanagawa, 232-8555

Other trials in Japan

About this study

Official title: A PHASE 3 MULTICENTER, OPEN LABEL, MULTI COHORT STUDY TO EVALUATE THE EFFICACY AND SAFETY OF SOMATROPIN IN JAPANESE PARTICIPANTS WITH PRADER-WILLI SYNDROME (PWS)

This is a multicenter, open label, multi cohort study to evaluate the efficacy and safety of somatropin in a cohort of Japanese participants with PWS.

Being tested
somatropin - GH naïve pediatric cohort, somatropin - GH treated cohort, somatropin - adult cohort
Medical subject headings
Prader-Willi Syndrome

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • somatropin - GH naïve pediatric cohortBiological

    somatropin 0.245 mg/kg/week

  • somatropin - GH treated cohortBiological

    somatropin 0.084 mg/kg/week

  • somatropin - adult cohortBiological

    somatropin 0.084 mg/kg/week

Study groups in NCT04697381
Study groupRoleWhat they receive
somatropin - GH naïve pediatric cohortExperimentalAll participants will receive somatropin.
Receives: Biological: somatropin - GH naïve pediatric cohort
somatropin - GH treated pediatric cohortExperimentalAll participants will receive somatropin
Receives: Biological: somatropin - GH treated cohort
somatropin - adult cohortExperimentalAll participants will receive somatropin
Receives: Biological: somatropin - adult cohort

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Change From Baseline to Month 12 in Lean Body Mass Measured by Dual-Energy X-ray Absorptiometry (DEXA): Adult Cohort

    Lean body mass, a measurement of body composition, was assessed by DEXA scan, and calculated as lean body mass (%) = lean body mass kilogram (kg) / (lean body mass [kg] + fat mass [kg]) *100.

    Measured: Baseline, Month 12

  2. Change From Baseline to Month 12 in Lean Body Mass Measured by DEXA: GH Naive Pediatric and GH Treated Pediatric Cohort

    Lean body mass, a measurement of body composition, was assessed by DEXA scan, and calculated as lean body mass (%) = lean body mass (kg) / (lean body mass [kg] + fat mass [kg])*100.

    Measured: Baseline, Month 12

Secondary outcomes (9)

  1. Change From Baseline to Month 12 in Lean Body Mass Measured by Bioelectrical Impedance Analysis (BIA)-Adult Cohort

    Lean body mass, a measurement of body composition, was assessed by DEXA scan, and calculated as lean body mass (%) = lean body mass (kg) / (lean body mass [kg] + fat mass [kg])*100.

    Measured: Baseline, Month 12

  2. Change From Baseline to Month 12 in Lean Body Mass Measured by BIA-GH Naive Pediatric and GH Treated Pediatric Cohort

    Lean body mass, a measurement of body composition, was assessed by DEXA scan, and calculated as lean body mass (%) = lean body mass (kg) / (lean body mass [kg] + fat mass [kg])*100.

    Measured: Baseline, Month 12

  3. Change From Baseline to Month 12 in Body Fat (Percentage) Measured by DEXA: Adult Cohort

    Body fat was assessed by DEXA scan. and calculated as body fat (%) = body fat (kg) / [lean body mass (kg) + body fat (kg)]*100.

    Measured: Baseline, Month 12

  4. Change From Baseline to Month 12 in Body Fat (Percentage) Measured by DEXA: GH Naive Pediatric and GH Treated Pediatric Cohort

    Body fat was assessed by DEXA scan. and calculated as body fat (%) = body fat (kg) / [lean body mass (kg) + body fat (kg)]*100.

    Measured: Baseline, Month 12

  5. Change From Baseline to Month 12 in Adipose Tissue Distribution Measured by Abdominal Computed Tomography (CT)

    Adipose tissue distribution was measured by abdominal CT. Areas of subcutaneous adipose tissue (SAT) (centimeter square [cm^2]), visceral adipose tissue (VAT) (cm^2) were measured at the level of the umbilicus by abdominal CT.

    Measured: Baseline, Month 12

  6. Change From Baseline to Month 6 in Lean Body Mass Measured by DEXA: Adult Cohort Only

    Lean body mass, a measurement of body composition, was assessed by DEXA scan, and calculated as lean body mass (%) = lean body mass (kg) / (lean body mass [kg] + fat mass [kg])*100.

    Measured: Baseline, Month 6

  7. Number of Participants With Treatment Emergent Adverse Events and Serious Adverse Events

    An adverse event was any untoward medical occurrence in administered medicinal product, event need not necessarily have a causal relationship with product treatment or usage. A serious adverse event was any untoward medical occurrence in a participant administered a medicinal or nutritional product (including pediatric formulas) at any dose that: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of hospitalization; resulted in persistent or significant disability/incapacity (substantial disruption of the ability to conduct normal life functions); resulted in congenital anomaly/birth defect. Treatment emergent AEs were events emerged during treatment period and were absent before treatment or that worsened relative to pretreatment state. TEAEs consist of SAEs and non-SAEs

    Measured: From day 1 up to 28 days after end of study treatment (maximum duration up to 38 months)

  8. Number of Participants With Laboratory Test Abnormalities

    Criteria for abnormal laboratory values for chemistry parameters: alanine aminotransferase, alkaline phosphatase greater than (>) 3.0*upper limit of normal (ULN), albumin > 1.2*ULN, urea nitrogen millimoles per liter (mmol/L) > 1.3*ULN, HDL cholesterol mmol/L less than (<) 0.8* lower limit of normal (LLN), LDL cholesterol mmol/L >1.2*ULN, triglycerides mmol/L > 1.3*ULN, thyrotropin milliunits per liter (mU/L) <0.8*LLN and >1.2*ULN, glucose (mmol/L) >1.5*ULN, hemoglobin A1C liter of cells per liter of blood (L/L) >1.3*ULN.

    Measured: From Day 1 up to 28 days after end of study treatment (maximum duration up to 38 months)

  9. Bone Maturation

    Bone maturation is the process whereby the tissue undergoes changes from the embryonic rudiment of bone to the adult form. Bone maturation was calculated as bone age divided by chronological age. Participants with bone maturation value greater than 1 is presented in this outcome measure.

    Measured: 12 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted6 Jan 2021
  2. Study start9 Feb 2021
  3. Primary completion6 Dec 2022
  4. Study completion15 Apr 2024

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Single group
Masking
None (open label)
Enrolment
33 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04697381
Sponsor's protocol ID
A6281323
Other IDs
2024-000101-32, NCT04697381
Status last verified
Dec 2025
First submitted
4 Jan 2021
Last updated
14 Jan 2026
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Publications

  • Kawai M, Murakami N, Horikawa R, Muroya K, Fujisawa Y, Hoshino Y, Okayama A, Sato T, Ebata N, Ogata T. Improvement in body composition of Japanese participants with Prader-Willi syndrome following somatropin treatment: an open-label, multi cohort Phase 3 study. Endocr J. 2025 Aug 1;72(8):925-935. doi: 10.1507/endocrj.EJ24-0659. Epub 2025 May 28.

    PubMed 40436776

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing somatropin - GH naïve pediatric cohort, somatropin - GH treated cohort and somatropin - adult cohort in people with Prader-Willi Syndrome, run by Pfizer at 5 sites in Japan.

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 16 inclusion and 6 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 14 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 5 sites in Japan. 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?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

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 5 Jun 2024). 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 From Baseline to Month 12 in Lean Body Mass Measured by Dual-Energy X-ray Absorptiometry (DEXA): Adult Cohort (time frame: Baseline, Month 12). The study lists 2 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 NCT04697381, 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 14 Jan 2026.

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