A Study of Vosoritide Versus Placebo in Children With Hypochondroplasia Aged 0 to < 36 Months

Eligibility Criteria

• 1. Participants must be 0 to \< 36 months of age at randomization.
• 2. Participants must have a confirmed genetic diagnosis of HCH (obtained via whole genome sequencing; presence of a FGFR3 pathogenic variant associated with HCH).
• 3. Participants aged 0 to \< 12 months must have a height Z-score of ≤ -1.0 SDS andparticipants aged ≥ 12 to \< 36 months must have a height Z-score of ≤ -2.0 SDS in reference to the average stature of the same sex and age, as calculated using the Center for Disease Control and Prevention (CDC) growth charts.
• 4. Participant's weight at the Day 1 visit (pre-treatment) must be ≥ 3 kg.
• 1. Short stature condition other than HCH (eg, ACH, trisomy 21, pseudoachondroplasia).
• 2. Have an unstable medical condition likely to require surgical intervention during the study period.
• 3. Taking any of the prohibited medications.
• 4. Have been treated with growth hormone, insulin-like growth factor 1 (IGF-1), or anabolic steroids in the 6 months prior to Screening, or long-term treatment (\> 3 months) at any time.
• 5. Require any investigational agent prior to completion of study period.
• 6. Have received another investigational product or investigational medical device within 30 days prior to the Screening visit.
• 7. Have used any other investigational product or investigational medical device for the treatment of HCH or short stature at any time.
• 8. Have current malignancy, history of malignancy, or currently under work-up for suspected malignancy.
• 9. Have known hypersensitivity to vosoritide or its excipients.
• 10. Have a condition or circumstance that, in the view of the investigator, places the participant at high risk for poor treatment compliance or for not completing the study.
• 11. Have any concurrent disease or condition that, in the view of the investigator, will interfere with study participation or safety evaluations, for any reason.