BMN 333 versus daily vosoritide for growth in children with achondroplasia

A Multicenter, Randomized, Operationally Seamless Phase 2/3 Study to Evaluate the Efficacy and Safety of BMN 333 Versus Vosoritide in Children With Achondroplasia

Phase2; Phase3 Interventional BioMarin Pharmaceutical · NCT07441876

This trial tests whether weekly BMN 333 injections help children with achondroplasia grow as well as daily vosoritide.

Quick facts

PhasePhase2; Phase3
Study typeInterventional
Enrollment160 (estimated)
Ages2 Years to 17 Years
SexAll
SponsorBioMarin Pharmaceutical Industry-sponsored
Locations4 sites (California City, California and 3 other locations)
Trial IDNCT07441876 on ClinicalTrials.gov

What this trial studies

This multicenter, multinational, randomized, active-controlled, operationally seamless Phase 2/3 study compares BMN 333 with vosoritide in treatment-naïve children with genetically confirmed achondroplasia. Phase 2 will identify the optimal BMN 333 dose and determine whether to proceed into Phase 3, and Phase 3 will compare the selected BMN 333 dose against daily vosoritide. Participants receive 52 weeks of treatment (BMN 333 once weekly; vosoritide once daily) and are followed for up to 61 weeks from screening to safety follow-up. Key eligibility includes specified age ranges, open epiphyses, ambulatory status, Tanner staging as required by phase, and no prior growth-promoting therapy.

Who should consider this trial

Good fit: Ideal candidates are treatment-naïve, ambulatory children with genetically confirmed achondroplasia who have open growth plates and meet the trial age criteria (Phase 2: 2 to <11 years; Phase 3: 2 to <18 years).

Not a fit: Children with other causes of short stature, prior growth-promoting treatments, closed epiphyses, or significant comorbid conditions excluded by the protocol are unlikely to benefit from participation.

Why it matters

Potential benefit: If successful, BMN 333 could provide similar or improved growth with once-weekly dosing, reducing injection frequency compared with daily vosoritide.

How similar studies have performed: Vosoritide has shown growth benefits in prior trials and is an approved therapy for achondroplasia, while BMN 333 is a newer agent being directly compared to vosoritide in this Phase 2/3 program.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Participants must be aged ≥ 2 to \< 11 years (Phase 2) or ≥ 2 to \< 18 years (Phase 3), at the time of signing the informed consent
2. Participants must have ACH (confirmed by documented genetic testing) and open epiphyses
3. Are Tanner Stage I (Phase 2) or any Tanner stage (Phase 3)
4. Are ambulatory and able to stand without assistance

Exclusion Criteria:

1. Have any short stature condition other than ACH (eg, hypochondroplasia, trisomy 21, pseudoachondroplasia, GH deficiency)
2. Have any of the following disorders: Hypothyroidism or hyperthyroidism, unless treated with evidence of normalized thyroid-stimulating hormone (TSH) levels, diabetes mellitus, unless considered well-controlled, autoimmune inflammatory disease, inflammatory bowel disease, autonomic neuropathy, anemia defined as hemoglobin \< 10 g/dL, vitamin D deficiency, significant hip pathology.
3. Have history of any renal insufficiency or cardiac/ cardiovascular disease that places the participant at increased risk of an adverse cardiac outcome in the setting of hypotension.
4. Have had bone fractures of the long bones or spine within 6 months prior to screening.
5. Have used vosoritide, any other approved product (except GH, as detailed below), investigational product, or investigational medical device for the treatment of ACH or short stature at any time
6. Have been treated with GH, insulin-like growth factor 1, or anabolic steroids in the 6 months prior to treatment start

Where this trial is running

California City, California and 3 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions AchondroplasiaACHBone Diseases, Developmental DwarfismBone DiseasesGenetic Diseases, InbornMusculoskeletal DiseasesNatriuretic Peptide, C-typeOsteochondrodysplasias
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.