Vosoritide: How a C-Type Natriuretic Peptide Drug Affects Growth in Achondroplasia

Vosoritide is a daily injection given to children with achondroplasia, the most common genetic cause of short stature with short limbs. It was the first medicine aimed at the cause of the condition rather than its complications. This page explains what the drug is, how it works on the growth plate, what the trials measured, what the United States prescribing information (the drug's official label) reports about side effects and who is covered, and which questions the research has not yet answered. Every trial figure below comes from the published trial summaries or from the label itself.


Table of Contents

  1. What Vosoritide Is
  2. How It Pushes Back Against the Overactive Growth Brake
  3. The First Trial in Children: Finding the Dose
  4. The Phase 3 Trial and the Label's Growth Figures
  5. What Happened When Children Kept Taking It
  6. The Trial in Babies and Children Under Five
  7. Side Effects Reported in the Label
  8. Who the Label Covers and How the Dose Is Set
  9. What Is Not Yet Known
  10. Related Drugs Aimed at the Same Pathway
  11. Key Research Papers
  12. Connections
  13. Featured Videos

What Vosoritide Is

Vosoritide is a laboratory-made copy of a natural body signal called C-type natriuretic peptide (CNP). The body makes C-type natriuretic peptide in many tissues, and one of its jobs is to tell the cartilage cells inside a child's growth plates to multiply and mature. The growth plates are the soft bands of cartilage near the ends of the long bones where a bone gets longer during childhood. The 2019 phase 2 trial report describes C-type natriuretic peptide as "a potent stimulator of endochondral ossification" — the process by which that cartilage is turned into new bone.

The natural signal does not last long in the blood because an enzyme called neutral endopeptidase breaks it down. According to the label, vosoritide is a chain of 39 amino acids: the last 37 amino acids of the human C-type natriuretic peptide sequence, plus two extra amino acids (proline and glycine) added to the front end to make the molecule resistant to that enzyme. It is made by bacteria (Escherichia coli) using recombinant DNA technology and is supplied as a powder that is mixed with sterile water before each injection.

Even with that change, the drug leaves the blood quickly. The label reports that it reaches its highest level about 15 minutes after the injection and that its mean half-life (the time for half of it to be cleared) ranged from 21.0 to 27.9 minutes in children. A daily injection is therefore needed. The label also reports that the drug's effect on the growth plate can be traced in the body: a marker of the cartilage-to-bone process, serum collagen type X marker, rose with daily treatment and stayed raised beyond 24 months.

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How It Pushes Back Against the Overactive Growth Brake

In achondroplasia, a single change in the gene for fibroblast growth factor receptor 3 (FGFR3) leaves that receptor switched on too much of the time. In a healthy growth plate, the receptor works as a brake: it slows the cartilage cells down so that growth stays in step with the rest of the body. With the receptor overactive, the brake is pressed too hard, the cartilage cells multiply and mature less than in a typical growth plate, and the long bones stay short. The Achondroplasia page explains the genetics in detail.

Vosoritide does not touch the faulty receptor itself. Instead, it works through a second, separate signal inside the same cartilage cells. The label describes the chain of events this way:

In other words, the faulty receptor keeps pressing its brake, and vosoritide eases the pressure further down the same line. The label adds that in animal models with open growth plates, the drug widened the growth plate and increased skeletal growth, and that in mice bred to carry receptor changes of this kind, the short-limbed body shape was partly or completely normalized. Those results were seen in animals; the human results are described in the trial sections below.

Because the drug acts through the cartilage of open growth plates, it has nothing to work on once the growth plates have closed at the end of puberty. That is why the label limits use to children whose growth plates are still open.

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The First Trial in Children: Finding the Dose

The first study in children with achondroplasia, published in 2019, was a phase 2 dose-finding study with a long-term extension. Its purpose was to see how the drug was tolerated and which dose worked.

A phase 2 study of this kind has no placebo group, so it can show a dose pattern and early safety but cannot prove how much of the growth came from the drug. That question went to the phase 3 trial.

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The Phase 3 Trial and the Label's Growth Figures

The phase 3 trial, published in The Lancet in 2020, compared vosoritide with a placebo injection (a dummy injection with no drug) for 52 weeks. It ran at 24 hospitals in seven countries: Australia, Germany, Japan, Spain, Turkey, the United States and the United Kingdom. Neither the families nor the doctors knew which children received the drug.

The main measure was annualized growth velocity — how many centimeters a child grows per year. The label's Table 5 gives the figures (61 children on placebo, 60 on vosoritide):

In plain terms, children on placebo grew at about the same speed as before, while children on vosoritide grew about 1.4 cm per year faster than they had been growing. The label states that the improvement was consistent across every predefined subgroup it analyzed, including sex, age group, stage of puberty, starting height and starting growth speed.

The label also reports two further measures from the same trial:

The trial authors' own interpretation in the Lancet summary was that vosoritide increased growth in children with achondroplasia, and that "it is not known whether final adult height will be increased, or what the harms of long-term therapy might be." In the same trial, 59 of 60 children on vosoritide (98%) and 60 of 61 on placebo (98%) had at least one adverse event; none of the serious adverse events were judged to be caused by the treatment, and no child died.

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What Happened When Children Kept Taking It

After the 52-week trial, children could move into an open-label extension, where everyone received vosoritide and everyone knew it. The results of an open-label extension are useful for seeing whether an effect lasts, but they lack a placebo group, so comparisons rely on outside reference data.

These longer-term comparisons set treated children against historical or external groups rather than against children randomly assigned to placebo, and the studies were funded by the drug's maker. Both points limit how firmly the size of the effect can be stated.

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The Trial in Babies and Children Under Five

Because the growth plates are most active early in life, a second placebo-controlled trial tested vosoritide in younger children. Its results were published in 2024.

The label's summary of this trial states that the most common adverse reactions in children under 5 were injection-site reactions (86%) and rash (28%), and that the overall safety profile was similar to that in older children.

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Side Effects Reported in the Label

The label's Table 3 lists the adverse reactions that occurred in at least 5% of children on vosoritide in the phase 3 trial and more often than on placebo (60 children on vosoritide, 61 on placebo):

Injection-site reactions

Injection-site reactions were common in both groups, because both groups had a daily injection: 51 of 60 children (85%) on vosoritide and 50 of 61 (82%) on placebo. The difference showed in how often they happened. Over 52 weeks, the vosoritide group had 6,983 injection-site reaction events and the placebo group 1,776, which the label gives as 120.4 events per person-year versus 29.2. Two children on vosoritide stopped treatment because of pain and anxiety with the injections.

Low blood pressure

The label's only warning is a risk of low blood pressure. The label reports that 8 of 60 children on vosoritide (13%) had a total of 11 episodes of a short-lived drop in blood pressure, compared with 3 of 61 (5%) on placebo. Most were picked up during close monitoring at clinic visits after a dose. The median time to onset was 31 minutes after the injection (range 18 to 120), and the drop resolved within a median of 31 minutes (range 5 to 90). Two of the 60 children on vosoritide (3%) each had one episode with symptoms — vomiting and/or dizziness — compared with none on placebo. The label lists dizziness, fatigue and nausea as the symptoms linked to a drop in blood pressure. It instructs that the child eat adequately and drink about 240 to 300 mL of fluid in the hour before each injection to reduce that risk. Children with significant heart or blood-vessel disease, and children taking blood-pressure-lowering medicines, were excluded from the trials, so the label has no trial data on them.

Other findings in the label

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Who the Label Covers and How the Dose Is Set

The current United States label (revised November 2025) states that vosoritide is "indicated to increase linear growth in pediatric patients with achondroplasia with open epiphyses." Epiphyses are the growth plates. The indication names no lower age limit: the label's dosing table starts at a body weight of 3 kg, and the label's pediatric-use section cites drug-level data in children from 4.5 months to 15 years and safety data from 4.4 months. Some descriptions give age 5 as the lower limit; the current label’s indication covers children of any age whose growth plates are open.

The label also states that this is an accelerated approval. The United States Food and Drug Administration (FDA) granted it on the basis of an improvement in growth speed, and "continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trial(s)." In other words, growth speed was accepted as an early measure, and further trials are expected to show the benefit that matters to families.

How the dose works

Decisions about starting, continuing or stopping a medicine belong with the child's clinicians and family.

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What Is Not Yet Known

The trials show that vosoritide makes children with achondroplasia grow faster while they take it. Several larger questions are still open in the published research:

Achondroplasia does not affect intelligence, and many adults with the condition, and organizations of people of short stature, regard height as only one part of the picture. The open questions above are about medical outcomes; how families weigh them is a separate, personal matter.

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Vosoritide opened the way for other drugs that work on the overactive growth-brake pathway, each from a different angle.

Navepegritide — a once-weekly C-type natriuretic peptide drug, now approved

Navepegritide is a prodrug (an inactive form that the body slowly converts into the active drug) that releases C-type natriuretic peptide steadily over a week, so it is injected once weekly instead of daily. In the APPROACH trial, 84 children aged 2 to 11 years were randomly assigned in a 2-to-1 ratio to navepegritide (100 micrograms per kilogram per week) or placebo for 52 weeks. Growth speed was 1.49 cm per year higher with navepegritide than with placebo (95% confidence interval 1.05 to 1.93). The trial also reported improvements in leg alignment and in a physical-functioning score in children younger than 5 years. Injection-site reaction rates were low, and no low blood pressure with symptoms was observed. Its United States label, first approved in 2026, covers children 2 years of age and older with achondroplasia and open growth plates, also under accelerated approval.

Infigratinib — a tablet that blocks the receptor directly, in trials

Infigratinib works differently: it is a small molecule taken by mouth that blocks the overactive receptor itself (and its two close relatives, fibroblast growth factor receptors 1 and 2). In the 2025 phase 2 dose-finding study of 72 children aged 3 to 11 years, the highest-dose group (0.25 mg per kilogram a day) showed a mean increase in growth speed of 2.50 cm per year at 18 months compared with the children's own starting values, along with a change in the upper-to-lower body segment ratio of −0.12; this study had no placebo group. The 2026 phase 3 trial then randomly assigned 114 children aged 3 to 17 years to infigratinib or placebo for 52 weeks. Growth speed was 1.74 cm per year higher with infigratinib (95% confidence interval 1.31 to 2.17), and the height score difference was 0.32. The difference in the upper-to-lower body segment ratio, −0.02, did not reach statistical significance. Serious adverse events occurred in 4 of 74 children (5%) on infigratinib and 1 of 39 (3%) on placebo, and none was judged related to the treatment.

Recifercept — development stopped

Recifercept was designed as a decoy: a soluble copy of the receptor meant to soak up the growth factors that switch the real receptor on. In its phase 2 study in children aged 2 to 10 years, there was no placebo group. Instead, researchers built a model of how each child would have grown without treatment from natural-history data, and compared it with the measured growth. For every dose tested, the measured standing height, sitting height and arm span at 6 and 12 months were comparable to the predicted untreated values, "suggesting no treatment effect." The authors reported that these results contributed to the decision to end recifercept's clinical development.

The two C-type natriuretic peptide drugs together

The 2026 meta-analysis that pooled the randomized trials of vosoritide and navepegritide (4 trials, 326 children) found overall and serious adverse-event rates comparable to placebo, with higher relative risks for injection-site reactions (1.65), hives (4.04) and swelling (3.57). Growth speed rose by a pooled 1.36 cm per year, with no short-term effect on body proportions.

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Key Research Papers

  1. Savarirayan R, Irving M, Bacino CA, et al. C-Type Natriuretic Peptide Analogue Therapy in Children with Achondroplasia. N Engl J Med. 2019;381(1):25-35. PubMed PMID: 31269546
  2. Savarirayan R, Tofts L, Irving M, et al. Once-daily, subcutaneous vosoritide therapy in children with achondroplasia: a randomised, double-blind, phase 3, placebo-controlled, multicentre trial. Lancet. 2020;396(10252):684-692. PubMed PMID: 32891212
  3. Savarirayan R, Tofts L, Irving M, et al. Safe and persistent growth-promoting effects of vosoritide in children with achondroplasia: 2-year results from an open-label, phase 3 extension study. Genet Med. 2021;23(12):2443-2447. PubMed PMID: 34341520
  4. Savarirayan R, Wilcox WR, Harmatz P, et al. Vosoritide therapy in children with achondroplasia aged 3-59 months: a multinational, randomised, double-blind, placebo-controlled, phase 2 trial. Lancet Child Adolesc Health. 2024;8(1):40-50. PubMed PMID: 37984383
  5. Savarirayan R, Irving M, Wilcox WR, et al. Sustained growth-promoting effects of vosoritide in children with achondroplasia from an ongoing phase 3 extension study. Med. 2025;6(5):100566. PubMed PMID: 39740666
  6. Savarirayan R, Hecht JT, Jayaram K, et al. Evaluating the impact of vosoritide on complications of achondroplasia. Genet Med. 2026;28(7):102584. PubMed PMID: 42001280
  7. Kamrul-Hasan ABM, Uday S, Nagendra L, et al. Achondroplasia management in the era of targeted therapies: a meta-analysis of C-type natriuretic peptide analogs. J Endocr Soc. 2026;10(7):bvag121. PubMed PMID: 42306228
  8. Pahuja M, Prakash C, Umrao A, et al. Efficacy and safety of Vosoritide in achondroplasia: A systematic review and meta-analysis. Indian J Med Res. 2026;163(1):78-87. PubMed PMID: 41934413
  9. Savarirayan R, McDonnell C, Bacino CA, et al. Once-Weekly Navepegritide in Children With Achondroplasia: The APPROACH Randomized Clinical Trial. JAMA Pediatr. 2026;180(1):18-25. PubMed PMID: 41247754
  10. Savarirayan R, De Bergua JM, Arundel P, et al. Oral Infigratinib Therapy in Children with Achondroplasia. N Engl J Med. 2025;392(9):865-874. PubMed PMID: 39555818
  11. Savarirayan R, Hoover-Fong J, Irving M, et al. Phase 3 Trial of Oral Infigratinib in Children with Achondroplasia. N Engl J Med. 2026;395(9):859-869. PubMed PMID: 42370681
  12. Qiao W, Boucher M, Slade A, et al. Natural disease course modeling of achondroplasia to evaluate the efficacy of recifercept in the absence of a placebo control arm in phase II study. CPT Pharmacometrics Syst Pharmacol. 2024;13(7):1103-1116. PubMed PMID: 38685585
  13. United States prescribing information for vosoritide for injection, revised November 2025. DailyMed, U.S. National Library of Medicine. DailyMed setid 228e8560-04a4-4bb1-a81f-29531a9e4d27
  14. United States prescribing information for navepegritide, first approved 2026. DailyMed, U.S. National Library of Medicine. DailyMed setid e01c1197-338f-414c-b804-808e129ebc8c

PubMed Topic Searches

  1. PubMed: vosoritide and achondroplasia
  2. PubMed: vosoritide extension studies
  3. PubMed: C-type natriuretic peptide and the growth plate
  4. PubMed: navepegritide and infigratinib in achondroplasia

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Connections

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