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Lonapegsomatropin

Phase 3

Turner Syndrome | Monoclonal antibody | Rare Disease |Ascendis Pharma A/S|Last Updated: Sep 2, 2026

Target and mechanism

Molecular targetGHR
Target classAgonist
ModalityMonoclonal antibody

Also known as Lonapegsomatropin [SKYTROFA®]

Success Probability

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Market & Valuation

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Trial Design

RandomizedACTIVE_CONTROLLED
Total Trials2
Total Enrollment234

FDA Designations

No designations recorded

Clinical trial landscape

Lonapegsomatropin · 4 trials · 8 indications

Phase 3 3Phase 2 1
NCT07221851Trial Investigating the Efficacy and Safety of Weekly Lonapegsomatropin Compared to Daily Somatropin in Children and Adolescents With Short Stature or Growth Failure Due to Growth Hormone Sufficient DisordersTurner Syndrome
RECRUITING186 Analytics
NCT05171855A Trial to Investigate Long Term Efficacy and Safety of Lonapegsomatropin in Adults With Growth Hormone DeficiencyAdult Growth Hormone Deficiency
COMPLETED220 Analytics
NCT04615273A Trial to Compare the Efficacy and Safety of Once-weekly Lonapegsomatropin With Placebo and a Daily Somatropin Product in Adults With Growth Hormone DeficiencyGrowth Hormone Deficiency
COMPLETED264 Analytics
PHASE3RECRUITING
Trial Investigating the Efficacy and Safety of Weekly Lonapegsomatropin Compared to Daily Somatropin in Children and Adolescents With Short Stature or Growth Failure Due to Growth Hormone Sufficient Disorders
Turner SyndromeUnlock trial analytics
PHASE3COMPLETED
A Trial to Investigate Long Term Efficacy and Safety of Lonapegsomatropin in Adults With Growth Hormone Deficiency
Adult Growth Hormone DeficiencyUnlock trial analytics
PHASE3COMPLETED
A Trial to Compare the Efficacy and Safety of Once-weekly Lonapegsomatropin With Placebo and a Daily Somatropin Product in Adults With Growth Hormone Deficiency
Growth Hormone DeficiencyUnlock trial analytics

Study Endpoints

Primary Endpoints

Annualized Height Velocity (AHV) (cm/year)
52 Weeks

To evaluate the efficacy of lonapegsomatropin as compared to somatropin in children and adolescents with TS, SHOX-D, SGA, or ISS

Number of Participants With Treatment-Emergent Adverse Events (TEAEs), Serious TEAEs and TEAE Leading to Study Discontinuation
Up to 52 Weeks

An Adverse Event (AE) was defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product and which did not necessarily have a causal relationship with the treatment. An AE was considered a TEAE if it occurred on or after the first dose of investigational product and was not present prior to the first dose, or it was present at the first dose but increased in severity during the trial. A serious AE was any untoward medical occurrence at any dose that met any of the following criteria: resulted in death; was life threatening; required or prolonged inpatient hospitalization; resulted in persistent or significant disability/incapacity; resulted in a congenital anomaly/birth defect in a neonate/infant born to a mother exposed to the trial drug or was considered a significant medical event by the investigator.

Change From Baseline in Trunk Percent Fat at Week 38
Baseline, Week 38

Trunk percent fat was assessed by dual-energy X-ray absorptiometry.

Secondary Endpoints

Annualized Height Velocity (AHV) (cm/year)
104 Weeks
Change from baseline in height standard deviation score (SDS)
52 Weeks and 104 Weeks
Change from baseline in Bone Age (years)
52 Weeks and 104 Weeks
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Lonapegsomatropin, once dailyEXPERIMENTALParticipants will receive Lonapegsomatropin by subcutaneous injection for 2 years (104 weeks)
somatropin, once dailyACTIVE_COMPARATORParticipants will receive somatropin by subcutaneous injection for 1 year (52 weeks) followed by lonapegsomatropin for 1 year (52 weeks)
Lonapegsomatropin/LonapegsomatropinEXPERIMENTALParticipants who had completed treatment with lonapegsomatropin in TCH-306 study were enrolled in the extension study and received lonapegsomatropin administered once weekly by subcutaneous injection for a treatment period of up to 52 weeks.
Placebo/LonapegsomatropinEXPERIMENTALParticipants who had completed treatment with placebo in TCH-306 study were enrolled in the extension study and received lonapegsomatropin administered once weekly by subcutaneous injection for a treatment period of up to 52 weeks.
Somatropin/LonapegsomatropinEXPERIMENTALParticipants who had completed treatment with somatropin in TCH-306 study were enrolled in the extension study and received lonapegsomatropin administered once weekly by subcutaneous injection for a treatment period of up to 52 weeks.
LonapegsomatropinEXPERIMENTALLonapegsomatropin administered once-weekly by subcutaneous injection.
PlaceboPLACEBO_COMPARATORPlacebo for Lonapegsomatropin administered once-weekly by subcutaneous injection.
SomatropinACTIVE_COMPARATORSomatropin administered once-daily by subcutaneous injection.
Lonapegsomatropin at 0.24 mg hGH/kg/weekEXPERIMENTALLonapegsomatropin at 0.24 mg hGH/kg/week administered once-weekly by subcutaneous injection
Lonapegsomatropin at 0.30 mg hGH/kg/weekEXPERIMENTALLonapegsomatropin at 0.30 mg hGH/kg/week administered once-weekly by subcutaneous injection
Lonapegsomatropin at 0.36 mg hGH/kg/weekEXPERIMENTALLonapegsomatropin at 0.36 mg hGH/kg/week administered once-weekly by subcutaneous injection
Somatropin at 0.05 mg/kg/dayACTIVE_COMPARATORSomatropin at 0.05 mg/kg/day administered once-daily by subcutaneous injection

Interventions

NameTypeDescription
Lonapegsomatropin [SKYTROFA®]COMBINATION_PRODUCTSubcutaneous injection once weekly
Somatropin Pen InjectorCOMBINATION_PRODUCTSubcutaneous injection once daily
LonapegsomatropinDRUGStudy participants were individually dosed with subcutaneous injection of Lonapegsomatropin once-weekly for 52 weeks.
PlaceboOTHERThe placebo for lonapegsomatropin drug product contained the same excipients as lonapegsomatropin drug product but does not contain lonapegsomatropin itself. The placebo solution was administered by subcutaneous (SC) injection via syringe and needle. Due to the different hGH dose requirements, depending on participant's age and concomitant use of oral estrogen, this trial has 3 dosing groups and the placebo received the same dose volume as if they were randomized to once-weekly lonapegsomatropin.
SomatropinDRUGSomatropin solution is provided in a pre-filled pen intended for daily subcutaneous injection. Due to the different hGH dose requirements, depending on participant's age and concomitant use of oral estrogen, this trial has 3 dosing groups per arm, followed by gradual increasing dose titration to a target maintenance dose.
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Eligibility Criteria

Age Range2 Years to 17 Years
SexALL
Healthy VolunteersNo
Study Sites43

Inclusion Criteria: 1. Chronological age between ≥2 and \<18 years, at start of screening. 2. Naïve to growth hormone and growth hormone promoting therapies. 3. Prepubertal. 4. Able to stand without assistance. 5. Diagnosis of TS, SHOX-D, SGA, or ISS with impaired growth or short stature, according...

Countries:United StatesFranceGermanyItalyRomaniaSouth KoreaSpainArmeniaAustraliaCanadaGeorgiaGreeceIsraelJapanMalaysiaPolandSerbiaSlovakiaTurkey (Türkiye)UkraineUnited KingdomDenmarkNetherlandsNew Zealand
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Recent Changes (Last 90 Days)

LOWSep 2, 2026NCT07221851lastUpdatePostDate: changed
LOWSep 2, 2026NCT07221851lastUpdatePostDate: changed
LOWSep 2, 2026NCT07221851lastUpdatePostDate: changed
LOWAug 20, 2026NCT07221851lastUpdatePostDate: changed
LOWAug 20, 2026NCT07221851lastUpdatePostDate: changed
LOWAug 20, 2026NCT07221851lastUpdatePostDate: changed
LOWAug 20, 2026NCT07221851lastUpdatePostDate: changed
LOWAug 11, 2026NCT07221851lastUpdatePostDate: changed
LOWAug 11, 2026NCT07221851lastUpdatePostDate: changed
MEDIUMAug 7, 2026NCT05171855TRIAL_REMOVED: changed
MEDIUMAug 7, 2026NCT04615273TRIAL_REMOVED: changed
MEDIUMAug 7, 2026NCT05171855TRIAL_REMOVED: changed
MEDIUMAug 7, 2026NCT04615273TRIAL_REMOVED: changed
MEDIUMAug 7, 2026NCT05171855TRIAL_REMOVED: changed
MEDIUMAug 7, 2026NCT04615273TRIAL_REMOVED: changed
LOWJul 28, 2026NCT07221851lastUpdatePostDate: changed
LOWJul 28, 2026NCT07221851lastUpdatePostDate: changed
LOWJul 10, 2026NCT07221851lastUpdatePostDate: changed
LOWJul 10, 2026NCT07221851lastUpdatePostDate: changed
LOWJul 9, 2026NCT07221851lastUpdatePostDate: changed

Frequently asked questions about Lonapegsomatropin

What is Lonapegsomatropin used for?

Lonapegsomatropin is an investigational once-weekly growth hormone therapy being studied for Turner Syndrome, Growth Hormone Deficiency, and Adult Growth Hormone Deficiency. It is a long-acting form of somatropin designed to treat conditions related to growth hormone deficiency in both children and adults.

What does Lonapegsomatropin target?

Lonapegsomatropin targets the growth hormone receptor (GHR) as an agonist. By activating this receptor, it mimics the action of natural growth hormone, which is intended to promote growth and development in patients with growth hormone deficiency or related conditions.

Who makes Lonapegsomatropin?

Lonapegsomatropin is developed by Ascendis Pharma A/S, a biopharmaceutical company listed on the NASDAQ under the ticker symbol ASND. The company is conducting clinical trials to evaluate the drug's safety and efficacy across multiple indications.

What phase is Lonapegsomatropin in?

Lonapegsomatropin is in Phase 3 clinical development for growth hormone deficiency and related conditions. It is an investigational drug and has not been approved by regulatory authorities. Clinical trials are ongoing to assess its efficacy and safety in adult and pediatric populations.

What clinical trials is Lonapegsomatropin in?

Lonapegsomatropin is being studied in several trials, including NCT04615273, a Phase 3 trial comparing it to placebo and daily somatropin in adults with growth hormone deficiency, and NCT05171855, a long-term safety study. A Phase 2 trial (NCT05690386) is evaluating it in Turner Syndrome, and NCT07221851 is a Phase 3 trial in children with short stature.

Is Lonapegsomatropin the same as SKYTROFA?

Lonapegsomatropin is also known as SKYTROFA. The drug is marketed under the brand name SKYTROFA, which is the same compound being investigated in clinical trials for growth hormone deficiency and Turner Syndrome.