A Study to Learn About Recifercept in Patients With Achondroplasia

Study Overview
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Brief Summary
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The purpose of this study is to learn about the study medicine (called recifercept) in people with achondroplasia. Achondroplasia is a very rare disease and patients of achondroplasia have short arms and legs. The study will include data already collected from a recifercept clinical trial and data collected from a separate study of achondroplasia. This study will compare patient experiences and will help the investigators determine if the study medicine, recifercept, is effective.

Official Title
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A Pilot Project to Evaluate the Feasibility of Constructing a Concurrent External Control for Recifercept

Conditions
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Achondroplasia

Intervention / Treatment
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* Other: Recifercept


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients from Study C4181005 who have completed Visits 1 through 11 (at D183) will be included in this project. To construct a concurrent external control, patients from Study C4181001 will need to meet the following inclusion criteria from Study C4181005 to be eligible for inclusion: Documented, confirmed genetic diagnosis of achondroplasia from historical medical records (test must have been performed at a laboratory fully accredited for genetic testing under local regulations) Aged ≥ 3 months to <11 years (up to the day before 11th birthday inclusive) at time of enrollment into the observational natural history study. Havecompleted at least 2 valid height/length measurements (at least 3 months apart) Assessed for Tanner stage 1 during physical examination before or at enrollment (must include assessment of breast development for females, testicular stage for males) Able to stand independently for height measurements (if ≥ 2 years of age at enrollment); If aged <2 years at enrollment, has a documented historical MRI brain/cervical spine performed in the previous 12 months. Have at least 6 months of available follow-up data after enrollment into the natural history study Exclusion Criteria: Patients meeting any of the following criteria will not be included in the study: Presence of severe obesity (BMI>95% percentile on Hoover-Fong BMI charts); Body weight <7kg or >30kg History of chronic kidney disease (CKD) or renal impairment History of receipt of any treatment that are known to potentially affect growth (including oral steroids > 5 days in the last 6 months before enrollment, high dose inhaled corticosteroids (>800 mcg/day beclametasone equivalent) and medication for attention deficient hyperactivity disorder. Less than 6 months since fracture or surgical procedure of any bone determined from the baseline visit date. Presence of any internal guided growth plates/devices History of removal of internal guided growth plates/devices within 6 months prior to enrollment

Ages Eligible for Study
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Minimum Age: 3 Months
Maximum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Recifercept cohort<br>Achondroplasia patients enrolled in the recifercept phase 2 clinical trial | Other: Recifercept<br>* Patients received recifercept intervention in the phase 2 clinical trial<br>|
| Natural history cohort<br>Achondroplasia patients enrolled in the achondroplasia natural history study | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Height growth | Increase in height growth above expected growth in reference population, defined as the height growth in the achondroplasia reference population +50% | 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Standing height | standing height in centimeters | 6 months | 
| Sitting height | sitting height in centimeters | 6 months | 
| Knee height | knee height in centimeters | 6 months | 
| Arm span | arm span in centimeters | 6 months | 
| Length of the legs | length of the legs in centimeters | 6 months | 
| Sitting height to standing height ratio | sitting height to standing height ratio (unitless) | 6 months | 
| arm span to height or length difference | arm span to height or length difference in centimeters | 6 months | 
| knee height to low segment ratio | knee height to low segment ratio (unitless) | 6 months | 
| Achondroplasia-related orthopaedic complications | lordosis, kyphoscoliosis, small foramen magnum, spinal stenosis | 6 months | 
| Other chondroplasia-related complications | sleep disordered breathing, acute otitis media, hydrocephalus | 6 months |