Peptide education
Vosoritide
Voxzogo
Vosoritide is a prescription medicine used to increase linear growth in children with achondroplasia whose growth plates remain open. It is an analog of C-type natriuretic peptide, a signaling molecule involved in bone growth.
Voxzogo has U.S. accelerated approval to increase linear growth in children with achondroplasia and open growth plates. A controlled trial found a higher growth rate over one year; that result does not by itself establish adult height.
Overview
Quick answer
The U.S. Voxzogo indication is for pediatric achondroplasia with open growth plates. It is not a general treatment for short stature or an approved medicine for increasing adult height.
What is Voxzogo used for?
The U.S. label covers linear growth in children with achondroplasia whose growth plates are open. The label says to stop when growth plates have closed and no further growth potential is confirmed.
How is the dose determined?
The prescribed dose is selected from the product's actual-body-weight table and given under the skin once daily. Vial strength and the volume after reconstitution also depend on the child's weight.
What did the phase 3 study find?
In a 52-week trial of 121 children with achondroplasia, the adjusted difference in annualized growth velocity favored vosoritide by 1.57 cm per year compared with placebo. The study measured growth rate during the trial rather than final adult height.
What should families know about blood pressure?
Temporary blood-pressure decreases have been reported. Caregivers should discuss the label's food and fluid instructions with the child's care team, especially for an infant. For dizziness, tiredness, or nausea after an injection, the instructions advise contacting the child's healthcare provider and having the child recline with legs raised.
Evidence
Evidence snapshot
Accelerated approval is based on improvement in annualized growth velocity.
The adjusted difference was 1.57 cm per year over the 52-week study.
A phase 2 study randomized 64 children under five and included 11 additional children who received open-label treatment.
The label describes injection-site reactions and transient decreases in blood pressure.
Claims
Common claims vs evidence
| Claim | Human evidence | Mechanistic evidence | Verdict |
|---|---|---|---|
| Vosoritide increased growth velocity in children with achondroplasia. | The 52-week phase 3 trial randomized 121 children to vosoritide or placebo. The adjusted between-group difference in annualized growth velocity was 1.57 cm per year in favor of vosoritide. | Vosoritide activates natriuretic peptide receptor-B and counters downstream FGFR3 signaling associated with reduced bone growth in achondroplasia. | The trial supports an effect on growth velocity in its studied population. A one-year growth-rate result does not itself establish final adult height. |
| The same dose applies to every child. | The U.S. label uses actual body weight to select dose, vial strength, and injection volume. Growth and body weight are monitored during treatment. | Dosing is product-specific and changes with the child's weight. | |
| The approval means all long-term clinical benefits have been established. | The U.S. indication received accelerated approval based on annualized growth velocity. The label says continued approval may depend on confirmatory evidence. | Growth velocity is the basis for the approval; the cited phase 3 trial did not establish final adult height. |
Bottom line
Main takeaway
Voxzogo is for children with achondroplasia whose growth plates are open. It is given with specialist monitoring.
Growth velocity describes the rate of growth during a period of observation. It is not the same measurement as final adult height.
Compare the age and dose used in each trial with the current U.S. weight-band table and accelerated-approval endpoint.
Identity
What it is
Vosoritide is a 39-amino-acid C-type natriuretic peptide analog supplied as a powder that must be reconstituted before injection.
Achondroplasia involves altered FGFR3 signaling that restricts growth at the growth plates.
Use context
Routes, doses, and cycle patterns
The Voxzogo label uses weight bands, while clinical trials reported weight-based study doses for specific age groups.
Human studies and product labels
Voxzogo U.S. label
- Purpose
- Linear growth in pediatric achondroplasia with open growth plates
- Context
- U.S. prescription label
- Route
- Subcutaneous
- Amount
- Selected from the label's actual-body-weight table
- Frequency
- Once daily
- Duration
- Until no further growth potential is confirmed by growth-plate closure
Vial strength and injection volume are also selected by weight. The label calls for regular assessment of weight, growth, and physical development.
Phase 3 achondroplasia trial
- Purpose
- Annualized growth velocity
- Context
- Published study regimen
- Route
- Subcutaneous
- Amount
- 15 mcg per kg of body weight
- Frequency
- Once daily
- Duration
- 52 weeks
The trial allowed enrollment from age 5 to under 18 years. The label reports actual participant ages of 5.1 to 14.9 years.
Younger-child phase 2 trial
- Purpose
- Study of children under five with achondroplasia
- Context
- Published age-stratified study regimen
- Route
- Subcutaneous
- Amount
- 30 mcg per kg while under two years old; 15 mcg per kg from age two
- Frequency
- Once daily
- Duration
- 52 weeks
The U.S. label uses a product-specific weight-band table rather than a single trial formula for every child.
What varies
- To help reduce the risk of low blood pressure, the U.S. label calls for adequate food before dosing and about 8 to 10 ounces (240 to 300 mL) of fluid within the preceding hour. Caregivers should discuss how to follow these instructions with the child's care team, especially for an infant, before changing feeding or fluid intake.
- The label calls for monitoring weight, growth, and physical development every 3 to 6 months, with dose adjustment for actual weight.
- Voxzogo is not recommended in the label for patients with eGFR below 60 mL per minute per 1.73 square meters.
Research
Research evidence
The 52-week phase 3 trial measured growth velocity in children with achondroplasia; a separate phase 2 study enrolled younger children.
| Study / evidence area | Population | Design | Product context | Main outcome | Limitations | Weight |
|---|---|---|---|---|---|---|
| Phase 3 achondroplasia trial | 121 ambulatory children with achondroplasia; the label reports actual ages of 5.1 to 14.9 years | Randomized, double-blind, placebo-controlled | Vosoritide 15 mcg per kg under the skin once daily for 52 weeks | Adjusted growth-velocity difference of 1.57 cm per year in favor of vosoritide | Eligibility was age 5 to under 18 years; the manufacturer-funded 52-week trial did not establish final adult height or all long-term outcomes | Controlled growth-velocity endpoint |
| Younger-child phase 2 trial | 64 randomized children aged 4.4 months to under five years; 11 additional children received open-label vosoritide | Randomized, double-blind, placebo-controlled with age-stratified dosing and an additional open-label group | Daily subcutaneous vosoritide or placebo for 52 weeks | At week 52, the difference in change in height Z score versus placebo was 0.25, with a 95% confidence interval from -0.02 to 0.53 | The confidence interval includes zero. Study doses and age groups are distinct from the U.S. product's weight-band instructions. | Controlled pediatric study |
Cautions
Safety and unknowns
- Injection-site reactions and temporary decreases in blood pressure are described in the label. Adequate food and fluids before a dose can reduce the risk of low blood pressure.
- The label does not recommend Voxzogo when eGFR is below 60 mL per minute per 1.73 square meters.
- The phase 3 trial measured one year of growth velocity; it did not determine final adult height or all effects of long-term treatment.
Product quality
Product identity and quality
Voxzogo is supplied in specific single-dose vial strengths with a diluent. The prepared concentration and injection volume depend on the prescribed vial and weight band.
Current weight
The prescribed dose and vial are chosen using actual body weight.
Vial and diluent
Reconstitution and injection volume are product-specific.
Growth monitoring
Dose and the decision to continue depend on growth and open growth plates.
Mechanism
How it is proposed to work
Vosoritide acts on a growth-regulating receptor and helps counter a signaling pathway that slows bone growth in achondroplasia.
Binding to natriuretic peptide receptor-B counteracts downstream FGFR3 signaling in the MAPK pathway.
FAQ
Common questions
Is Voxzogo approved to increase height in adults?
No. The U.S. label covers pediatric patients with achondroplasia whose growth plates remain open.
Details
Technical details
Sources
References
- 1.
DailyMed. Voxzogo prescribing information
U.S. accelerated-approval indication, weight-based dosing, administration, and safety.
- 2.
doi:10.1016/S0140-6736(20)31541-5 PMID:32891212 NCT03197766
Placebo-controlled 52-week trial of annualized growth velocity in children with achondroplasia.
- 3.
PubMed. Vosoritide therapy in young children with achondroplasia: a randomized phase 2 trial
doi:10.1016/S2352-4642(23)00265-1 PMID:37984383 NCT03583697
Randomized study of younger children; its weight-based study regimens are not a substitute for the U.S. label table.