Trial Outcomes & Findings for A Study Of Safety, Tolerability And Effectiveness Of Recifercept In Children With Achondroplasia (NCT NCT04638153)

Last Updated: 2024-02-15

Results Overview

Treatment-related AE was any untoward medical occurrence attributed to study intervention in a participant who received study intervention. Serious adverse event (SAE) was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent AE is defined as an AE with onset date occurring during the on-treatment period. Relatedness to recifercept was assessed by the investigator (Yes/No).

Recruitment status

TERMINATED

Study phase

PHASE2

Target enrollment

60 participants

Primary outcome timeframe

The first dose up to 28 to 35 days after the last dose of study intervention (13 months)

Results posted on

2024-02-15

Participant Flow

A total of 60 participants were enrolled, of which, 58 participants were assigned to treatment and 2 participants were not randomized, Out of 58 participants, 57 participants were treated. Note: The pharmacokinetics (PK) study cohort was not enrolled due to early study termination,

Participant milestones

Participant milestones
Measure	Recifercept 1 mg/kg QW Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Overall Study STARTED	20	19	18
Overall Study COMPLETED	16	17	3
Overall Study NOT COMPLETED	4	2	15

Reasons for withdrawal

Reasons for withdrawal
Measure	Recifercept 1 mg/kg QW Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Overall Study Withdrawal by parent/guardian	0	0	1
Overall Study Study terminated by sponsor	4	2	14

Baseline Characteristics

A Study Of Safety, Tolerability And Effectiveness Of Recifercept In Children With Achondroplasia

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.	Total n=57 Participants Total of all reporting groups
Age, Continuous	5.75 years STANDARD_DEVIATION 2.84 • n=5 Participants	5.16 years STANDARD_DEVIATION 2.59 • n=7 Participants	5.83 years STANDARD_DEVIATION 2.31 • n=5 Participants	5.58 years STANDARD_DEVIATION 2.57 • n=4 Participants
Sex: Female, Male Female	9 Participants n=5 Participants	9 Participants n=7 Participants	6 Participants n=5 Participants	24 Participants n=4 Participants
Sex: Female, Male Male	11 Participants n=5 Participants	10 Participants n=7 Participants	12 Participants n=5 Participants	33 Participants n=4 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	3 Participants n=5 Participants	0 Participants n=7 Participants	2 Participants n=5 Participants	5 Participants n=4 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	16 Participants n=5 Participants	19 Participants n=7 Participants	15 Participants n=5 Participants	50 Participants n=4 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants	2 Participants n=4 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Asian	3 Participants n=5 Participants	0 Participants n=7 Participants	2 Participants n=5 Participants	5 Participants n=4 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) White	15 Participants n=5 Participants	19 Participants n=7 Participants	14 Participants n=5 Participants	48 Participants n=4 Participants
Race (NIH/OMB) More than one race	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants	2 Participants n=4 Participants
Race (NIH/OMB) Unknown or Not Reported	1 Participants n=5 Participants	0 Participants n=7 Participants	1 Participants n=5 Participants	2 Participants n=4 Participants

PRIMARY outcome

Timeframe: The first dose up to 28 to 35 days after the last dose of study intervention (13 months)

Population: Analysis population included all participants who received at least 1 dose of recifercept.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs) Treatment-related AE	7 Participants	15 Participants	14 Participants
Number of Participants With Treatment Emergent Treatment-Related Adverse Events (AEs) Treatment-related SAE	0 Participants	0 Participants	0 Participants

PRIMARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept.

Height growth was defined as the ratio of observed change from baseline in standing height to the expected change from baseline in the reference population.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Least Square Mean of Change From Baseline Height Growth at Month 3, Month 6, Month 9, and Month 12 Month 3	1.1 Ratio Interval 0.8 to 1.4	0.9 Ratio Interval 0.6 to 1.2	0.6 Ratio Interval 0.3 to 0.9
Least Square Mean of Change From Baseline Height Growth at Month 3, Month 6, Month 9, and Month 12 Month 6	0.9 Ratio Interval 0.7 to 1.1	1.1 Ratio Interval 0.9 to 1.3	1.0 Ratio Interval 0.8 to 1.2
Least Square Mean of Change From Baseline Height Growth at Month 3, Month 6, Month 9, and Month 12 Month 9	1.0 Ratio Interval 0.8 to 1.1	1.0 Ratio Interval 0.8 to 1.1	1.0 Ratio Interval 0.8 to 1.1
Least Square Mean of Change From Baseline Height Growth at Month 3, Month 6, Month 9, and Month 12 Month 12	1.0 Ratio Interval 0.8 to 1.1	1.0 Ratio Interval 0.9 to 1.1	0.9 Ratio Interval 0.7 to 1.1

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Pulse rate measurements were preceded by at least 5 minutes of rest for the participant in a quiet setting without distractions (eg, television, cell phones) where possible (with consideration of the age of the child). Pulse rate was summarized by treatment in accordance with the sponsor reporting standards.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Pulse Rate at Month 3, Month 6, Month 9, and Month 12 Baseline	96.40 beats per minute (BPM) Standard Deviation 16.583	97.58 beats per minute (BPM) Standard Deviation 21.823	94.50 beats per minute (BPM) Standard Deviation 15.497
Change From Baseline in Pulse Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	-1.47 beats per minute (BPM) Standard Deviation 13.639	-6.05 beats per minute (BPM) Standard Deviation 20.871	-2.94 beats per minute (BPM) Standard Deviation 16.913
Change From Baseline in Pulse Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	-2.65 beats per minute (BPM) Standard Deviation 8.760	-1.44 beats per minute (BPM) Standard Deviation 15.659	-2.20 beats per minute (BPM) Standard Deviation 15.880
Change From Baseline in Pulse Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-4.35 beats per minute (BPM) Standard Deviation 16.035	-2.18 beats per minute (BPM) Standard Deviation 17.746	-15.20 beats per minute (BPM) Standard Deviation 14.853
Change From Baseline in Pulse Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	1.17 beats per minute (BPM) Standard Deviation 15.484	-0.75 beats per minute (BPM) Standard Deviation 34.012	-11.50 beats per minute (BPM) Standard Deviation 37.477

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Respiratory rate was obtained with participant in the seated position, after having sat calmly for at least 5 minutes. Respiratory rate was summarized by treatment in accordance with the sponsor reporting standards.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Respiratory Rate at Month 3, Month 6, Month 9, and Month 12 Baseline	23.15 breaths/min Standard Deviation 4.603	24.37 breaths/min Standard Deviation 3.905	23.39 breaths/min Standard Deviation 5.863
Change From Baseline in Respiratory Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	0.47 breaths/min Standard Deviation 5.691	-1.00 breaths/min Standard Deviation 2.809	-1.53 breaths/min Standard Deviation 4.939
Change From Baseline in Respiratory Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	-1.12 breaths/min Standard Deviation 3.516	-0.94 breaths/min Standard Deviation 4.221	0.53 breaths/min Standard Deviation 4.502
Change From Baseline in Respiratory Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-1.06 breaths/min Standard Deviation 3.473	-0.94 breaths/min Standard Deviation 4.507	-1.30 breaths/min Standard Deviation 6.945
Change From Baseline in Respiratory Rate at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	2.00 breaths/min Standard Deviation 5.132	-3.75 breaths/min Standard Deviation 4.979	2.00 breaths/min Standard Deviation 15.556

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Blood pressure measurements were preceded by at least 5 minutes of rest for the participant in a quiet setting without distractions (eg, television, cell phones) where possible (with consideration of the age of the child). Supine systolic blood pressure (SBP) and diastolic blood pressure (DBP) were summarized by treatment in accordance with the sponsor reporting standards.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Baseline (Supine DBP)	66.55 millimeters of mercury (mm Hg) Standard Deviation 9.870	67.05 millimeters of mercury (mm Hg) Standard Deviation 9.897	62.11 millimeters of mercury (mm Hg) Standard Deviation 13.244
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 3 (Supine DBP)	-0.76 millimeters of mercury (mm Hg) Standard Deviation 12.179	-4.47 millimeters of mercury (mm Hg) Standard Deviation 8.618	-0.29 millimeters of mercury (mm Hg) Standard Deviation 12.849
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 6 (Supine DBP)	-3.65 millimeters of mercury (mm Hg) Standard Deviation 14.845	-0.83 millimeters of mercury (mm Hg) Standard Deviation 10.837	5.27 millimeters of mercury (mm Hg) Standard Deviation 12.920
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 9 (Supine DBP)	-3.41 millimeters of mercury (mm Hg) Standard Deviation 12.846	-2.50 millimeters of mercury (mm Hg) Standard Deviation 11.408	-2.44 millimeters of mercury (mm Hg) Standard Deviation 13.492
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 12 (Supine DBP)	-3.14 millimeters of mercury (mm Hg) Standard Deviation 16.385	-1.13 millimeters of mercury (mm Hg) Standard Deviation 13.953	-4.50 millimeters of mercury (mm Hg) Standard Deviation 21.920
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Baseline (Supine SBP)	105.70 millimeters of mercury (mm Hg) Standard Deviation 10.732	118.37 millimeters of mercury (mm Hg) Standard Deviation 22.056	106.28 millimeters of mercury (mm Hg) Standard Deviation 14.199
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 3 (Supine SBP)	10.47 millimeters of mercury (mm Hg) Standard Deviation 14.261	-5.68 millimeters of mercury (mm Hg) Standard Deviation 21.445	4.82 millimeters of mercury (mm Hg) Standard Deviation 15.134
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 6 (Supine SBP)	1.88 millimeters of mercury (mm Hg) Standard Deviation 21.863	3.94 millimeters of mercury (mm Hg) Standard Deviation 17.424	5.73 millimeters of mercury (mm Hg) Standard Deviation 14.587
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 9 (Supine SBP)	2.59 millimeters of mercury (mm Hg) Standard Deviation 15.732	-2.94 millimeters of mercury (mm Hg) Standard Deviation 16.364	2.33 millimeters of mercury (mm Hg) Standard Deviation 19.371
Change From Baseline in Blood Pressure at Month 3, Month 6, Month 9, and Month 12 Change at Month 12 (Supine SBP)	3.57 millimeters of mercury (mm Hg) Standard Deviation 27.700	-11.75 millimeters of mercury (mm Hg) Standard Deviation 31.865	-6.50 millimeters of mercury (mm Hg) Standard Deviation 4.950

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Temperature was obtained with participant in the seated position, after having sat calmly for at least 5 minutes. Temperature measurements were summarized by treatment in accordance with the sponsor reporting standards.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Temperature at Month 3, Month 6, Month 9, and Month 12 Baseline	36.57 Degree Celsius (°C) Standard Deviation 0.441	36.43 Degree Celsius (°C) Standard Deviation 0.519	36.58 Degree Celsius (°C) Standard Deviation 0.466
Change From Baseline in Temperature at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	-0.06 Degree Celsius (°C) Standard Deviation 0.362	-0.04 Degree Celsius (°C) Standard Deviation 0.297	0.11 Degree Celsius (°C) Standard Deviation 0.493
Change From Baseline in Temperature at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	-0.08 Degree Celsius (°C) Standard Deviation 0.493	-0.02 Degree Celsius (°C) Standard Deviation 0.298	-0.03 Degree Celsius (°C) Standard Deviation 0.417
Change From Baseline in Temperature at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-0.16 Degree Celsius (°C) Standard Deviation 0.614	-0.12 Degree Celsius (°C) Standard Deviation 0.437	-0.20 Degree Celsius (°C) Standard Deviation 0.503
Change From Baseline in Temperature at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	-0.21 Degree Celsius (°C) Standard Deviation 0.313	-0.14 Degree Celsius (°C) Standard Deviation 0.316	0.30 Degree Celsius (°C) Standard Deviation 0.141

SECONDARY outcome

Timeframe: Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

A physical examination included, at a minimum, assessments of the cardiovascular, respiratory, gastrointestinal systems and skin. Physical examination assessments were summarized by treatment in accordance with the sponsor reporting standards.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Cardiovascular at Month 3	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Cardiovascular at Month 6	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Cardiovascular at Month 9	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Cardiovascular at Month 12	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Gastrointestinal at Month 3	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Gastrointestinal at Month 6	0 Participants	1 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Gastrointestinal at Month 9	0 Participants	2 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Gastrointestinal at Month 12	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Lungs at Month 3	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Lungs at Month 6	0 Participants	2 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Lungs at Month 9	0 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Lungs at Month 12	1 Participants	0 Participants	0 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Skin at Month 3	2 Participants	3 Participants	1 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Skin at Month 6	1 Participants	4 Participants	2 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Skin at Month 9	3 Participants	3 Participants	2 Participants
Number of Participants With Abnormal Physical Examination Findings at Month 3, Month 6, Month 9, and Month 12 Abnormal Skin at Month 12	2 Participants	3 Participants	1 Participants

SECONDARY outcome

Timeframe: Baseline to Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept.

Participants with laboratory abnormalities that met pre-specified criteria included following parameters: hematology (corpuscular volume, corpuscular hemoglobin, corpuscular hemoglobin concentration, platelet, leukocytes, lymphocytes, neutrophils, eosinophils, and monocytes), and chemistry (bilirubin, alkaline phosphatase, albumin, urea nitrogen, urate, potassium, phosphate, bicarbonate).

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Ery. Mean Corpuscular Volume (fL) < 0.9 x lower limit of normal (LLN)	0 Participants	1 Participants	2 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Ery. Mean Corpuscular Volume (fL) > 1.1 x upper limit of normal (ULN)	1 Participants	0 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Ery. Mean Corpuscular Hemoglobin (pg/cell) < 0.9 x LLN	0 Participants	1 Participants	2 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Ery. Mean Corpuscular Hemoglobin Concentration (g/dL) < 0.9x LLN	0 Participants	1 Participants	1 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Platelets (10^9/L) > 1.75 x ULN	0 Participants	0 Participants	1 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Leukocytes (10^9/L) < 0.6 x LLN	1 Participants	0 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Lymphocytes (10^9/L) < 0.8 x LLN	5 Participants	9 Participants	4 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Neutrophils (10^9/L) < 0.8x LLN	1 Participants	0 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Neutrophils (10^9/L) > 1.2 x ULN	1 Participants	0 Participants	1 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Eosinophils (10^9/L) > 1.2 x ULN	1 Participants	4 Participants	3 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Monocytes (10^9/L) > 1.2 x ULN	4 Participants	1 Participants	1 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Bilirubin (mg/dL) > 1.5 x ULN	0 Participants	1 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Alkaline Phosphatase (U/L) > 3.0 x ULN	1 Participants	0 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Albumin (g/dL) > 1.2 x ULN	2 Participants	3 Participants	1 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Urea Nitrogen (mg/dL) > 1.3 x ULN	2 Participants	5 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Urate (mg/dL) > 1.2 x ULN	2 Participants	1 Participants	0 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Potassium (mEq/L) > 1.1 x ULN	2 Participants	4 Participants	4 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Phosphate (mg/dL) < 0.8 x LLN	0 Participants	0 Participants	1 Participants
Number of Participants With Laboratory Abnormalities (Without Regard to Baseline Abnormality) Bicarbonate (mEq/L) < 0.9 x LLN	2 Participants	2 Participants	4 Participants

SECONDARY outcome

Timeframe: Pre-dose on Day(s) 4, 8, 15, 29, 61, 91, 183, 273, 365

Population: Analysis population included all participants who received at least 1 dose of recifercept and had at least one evaluable concentration. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Ctrough was defined as pre-dose serum concentration during dosing and observed directly from data.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 4	215.8 nanograms per millilitre (ng/mL) Standard Deviation 63.28	517.3 nanograms per millilitre (ng/mL) Standard Deviation 174.18	1785.2 nanograms per millilitre (ng/mL) Standard Deviation 651.92
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 8	95.3 nanograms per millilitre (ng/mL) Standard Deviation 23.35	614.6 nanograms per millilitre (ng/mL) Standard Deviation 228.35	2682.6 nanograms per millilitre (ng/mL) Standard Deviation 912.79
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 15	137.1 nanograms per millilitre (ng/mL) Standard Deviation 39.26	868.1 nanograms per millilitre (ng/mL) Standard Deviation 341.98	3199.4 nanograms per millilitre (ng/mL) Standard Deviation 1311.65
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 29	154.3 nanograms per millilitre (ng/mL) Standard Deviation 46.91	940.8 nanograms per millilitre (ng/mL) Standard Deviation 415.45	3804.4 nanograms per millilitre (ng/mL) Standard Deviation 1573.91
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 61	183.8 nanograms per millilitre (ng/mL) Standard Deviation 75.76	974.8 nanograms per millilitre (ng/mL) Standard Deviation 604.47	3431.4 nanograms per millilitre (ng/mL) Standard Deviation 1477.48
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 91	225.5 nanograms per millilitre (ng/mL) Standard Deviation 90.91	944.8 nanograms per millilitre (ng/mL) Standard Deviation 466.38	3702.3 nanograms per millilitre (ng/mL) Standard Deviation 2074.64
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 183	370.9 nanograms per millilitre (ng/mL) Standard Deviation 424.80	1078.9 nanograms per millilitre (ng/mL) Standard Deviation 563.83	5185.5 nanograms per millilitre (ng/mL) Standard Deviation 3190.30
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 273	278.2 nanograms per millilitre (ng/mL) Standard Deviation 140.41	1340.8 nanograms per millilitre (ng/mL) Standard Deviation 695.10	3879.6 nanograms per millilitre (ng/mL) Standard Deviation 3027.59
Pre-Dose Serum Concentration (Ctrough) of Recifercept Day 365	249.5 nanograms per millilitre (ng/mL) Standard Deviation 174.54	1320.4 nanograms per millilitre (ng/mL) Standard Deviation 662.18	6766.7 nanograms per millilitre (ng/mL) Standard Deviation 3145.18

SECONDARY outcome

Timeframe: The first dose up to 28 to 35 days after the last dose of study intervention (13 months)

Population: Analysis population included all participants who received at least 1 dose of recifercept.

The immunogenicity was measured by presence of ADA and NAb in participants treated with recifercept and summarized by dose regimen.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Number of Participants With Positive Anti-Drug Antibodies (ADA) and Neutralizing Antibody (NAb) of Recifercept Overall incidence of positive NAb	13 Participants	16 Participants	16 Participants
Number of Participants With Positive Anti-Drug Antibodies (ADA) and Neutralizing Antibody (NAb) of Recifercept Overall incidence of positive ADA	16 Participants	18 Participants	17 Participants

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Overall Number of Participants Analyzed" was based on age 2-10 years at baseline. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Sitting/standing height ratio was the ratio of sitting height to standing height.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=18 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=18 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Sitting/Standing Height Ratio at Month 3, Month 6, Month 9, and Month 12 Baseline	0.7 Ratio Standard Deviation 0.02	0.7 Ratio Standard Deviation 0.02	0.7 Ratio Standard Deviation 0.02
Change From Baseline in Sitting/Standing Height Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	0.0 Ratio Standard Deviation 0.01	-0.0 Ratio Standard Deviation 0.01	0.0 Ratio Standard Deviation 0.01
Change From Baseline in Sitting/Standing Height Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	0.0 Ratio Standard Deviation 0.01	-0.0 Ratio Standard Deviation 0.01	-0.0 Ratio Standard Deviation 0.01
Change From Baseline in Sitting/Standing Height Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-0.0 Ratio Standard Deviation 0.01	-0.0 Ratio Standard Deviation 0.01	-0.0 Ratio Standard Deviation 0.01
Change From Baseline in Sitting/Standing Height Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	-0.0 Ratio Standard Deviation 0.01	-0.0 Ratio Standard Deviation 0.01	0.0 Ratio Standard Deviation 0.00

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept.

Arm span to standing height/length difference was the difference between arm span and standing height.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Least Square Mean of Change From Baseline Arm Span to Standing Height/Length Difference at Month 3, Month 6, Month 9, and Month 12 Month 3	0.4 centimeter (cm) Interval -0.2 to 1.0	0.0 centimeter (cm) Interval -0.5 to 0.6	-0.6 centimeter (cm) Interval -1.2 to 0.0
Least Square Mean of Change From Baseline Arm Span to Standing Height/Length Difference at Month 3, Month 6, Month 9, and Month 12 Month 6	0.2 centimeter (cm) Interval -0.6 to 1.0	0.7 centimeter (cm) Interval -0.1 to 1.5	-0.5 centimeter (cm) Interval -1.3 to 0.3
Least Square Mean of Change From Baseline Arm Span to Standing Height/Length Difference at Month 3, Month 6, Month 9, and Month 12 Month 9	0.7 centimeter (cm) Interval 0.1 to 1.2	0.7 centimeter (cm) Interval 0.2 to 1.2	0.0 centimeter (cm) Interval -0.6 to 0.6
Least Square Mean of Change From Baseline Arm Span to Standing Height/Length Difference at Month 3, Month 6, Month 9, and Month 12 Month 12	1.0 centimeter (cm) Interval 0.0 to 2.1	0.9 centimeter (cm) Interval 0.0 to 1.9	0.3 centimeter (cm) Interval -1.4 to 2.1

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Knee height : lower segment ratio was the ratio of knee to heel length to the difference between standing height and sitting height.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Knee Height : Lower Segment Ratio at Month 3, Month 6, Month 9, and Month 12 Baseline	0.81 Ratio Standard Deviation 0.052	0.84 Ratio Standard Deviation 0.058	0.80 Ratio Standard Deviation 0.035
Change From Baseline in Knee Height : Lower Segment Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	-0.00 Ratio Standard Deviation 0.020	-0.01 Ratio Standard Deviation 0.052	0.02 Ratio Standard Deviation 0.035
Change From Baseline in Knee Height : Lower Segment Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	-0.00 Ratio Standard Deviation 0.028	-0.02 Ratio Standard Deviation 0.062	0.00 Ratio Standard Deviation 0.026
Change From Baseline in Knee Height : Lower Segment Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-0.00 Ratio Standard Deviation 0.027	-0.02 Ratio Standard Deviation 0.065	0.01 Ratio Standard Deviation 0.026
Change From Baseline in Knee Height : Lower Segment Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	0.00 Ratio Standard Deviation 0.028	-0.02 Ratio Standard Deviation 0.081	0.02 Ratio Standard Deviation 0.023

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Head circumference or the occipito-frontal circumference is the greatest of the cranial dimensions which passes around the forehead anteriorly and the external occipital protruberance posteriorly. It is a routine part of the physical examination of a child and is of great importance in detecting abnormal patterns of cranial growth. Occipito-frontal circumference data were summarized for each treatment arm.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Occipito-Frontal Circumference at Month 3, Month 6, Month 9, and Month 12 Baseline	54.56 cm Standard Deviation 2.877	55.00 cm Standard Deviation 2.179	56.13 cm Standard Deviation 1.949
Change From Baseline in Occipito-Frontal Circumference at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	0.19 cm Standard Deviation 0.345	0.19 cm Standard Deviation 0.382	0.30 cm Standard Deviation 0.515
Change From Baseline in Occipito-Frontal Circumference at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	0.33 cm Standard Deviation 0.396	0.35 cm Standard Deviation 0.506	0.30 cm Standard Deviation 0.437
Change From Baseline in Occipito-Frontal Circumference at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	0.46 cm Standard Deviation 0.619	0.35 cm Standard Deviation 0.597	0.54 cm Standard Deviation 0.588
Change From Baseline in Occipito-Frontal Circumference at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	0.87 cm Standard Deviation 1.106	0.53 cm Standard Deviation 0.557	0.00 cm Standard Deviation 0.424

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Ratio of occipito-frontal distance to occipito-mid-face measurements was summarized for each treatment arm.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Occipito-Frontal to Occipito-Mid-Face Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	-0.04 Ratio Standard Deviation 0.034	-0.01 Ratio Standard Deviation 0.028	0.00 Ratio Standard Deviation 0.018
Change From Baseline in Occipito-Frontal to Occipito-Mid-Face Ratio at Month 3, Month 6, Month 9, and Month 12 Baseline	1.00 Ratio Standard Deviation 0.053	1.00 Ratio Standard Deviation 0.055	1.00 Ratio Standard Deviation 0.058
Change From Baseline in Occipito-Frontal to Occipito-Mid-Face Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	0.01 Ratio Standard Deviation 0.024	0.00 Ratio Standard Deviation 0.039	-0.01 Ratio Standard Deviation 0.034
Change From Baseline in Occipito-Frontal to Occipito-Mid-Face Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	-0.01 Ratio Standard Deviation 0.056	0.00 Ratio Standard Deviation 0.027	-0.02 Ratio Standard Deviation 0.039
Change From Baseline in Occipito-Frontal to Occipito-Mid-Face Ratio at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-0.01 Ratio Standard Deviation 0.042	-0.01 Ratio Standard Deviation 0.034	-0.02 Ratio Standard Deviation 0.031

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Height Standard Deviation Score (SDS) (z-score) was calculated as the difference between mean observed standing height at each visit and mean value of reference population divided by standard deviation of reference population. SDS indicates how similar the participant was to the reference population.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=18 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=18 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Height Standard Deviation Score (Z-Score) at Month 3, Month 6, Month 9, and Month 12 Baseline	-0.2 SDS Standard Deviation 0.91	0.1 SDS Standard Deviation 0.91	0.2 SDS Standard Deviation 1.26
Change From Baseline in Height Standard Deviation Score (Z-Score) at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	0.0 SDS Standard Deviation 0.13	-0.0 SDS Standard Deviation 0.17	0.0 SDS Standard Deviation 0.26
Change From Baseline in Height Standard Deviation Score (Z-Score) at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	0.0 SDS Standard Deviation 0.21	0.0 SDS Standard Deviation 0.21	0.0 SDS Standard Deviation 0.24
Change From Baseline in Height Standard Deviation Score (Z-Score) at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	0.0 SDS Standard Deviation 0.26	0.0 SDS Standard Deviation 0.21	0.0 SDS Standard Deviation 0.20
Change From Baseline in Height Standard Deviation Score (Z-Score) at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	0.0 SDS Standard Deviation 0.33	0.1 SDS Standard Deviation 0.26	-0.2 SDS Standard Deviation 0.17

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Fixed flexion angles at elbow data were presented for each treatment arm. An average of a participant's elbow extension measurements over a visit was computed.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Fixed Flexion Angles at Elbow at Month 3, Month 6, Month 9, and Month 12 Baseline	-11.33 degrees (°) Standard Deviation 20.002	-18.31 degrees (°) Standard Deviation 12.707	-6.45 degrees (°) Standard Deviation 17.628
Change From Baseline in Fixed Flexion Angles at Elbow at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	2.23 degrees (°) Standard Deviation 8.976	4.29 degrees (°) Standard Deviation 10.519	1.09 degrees (°) Standard Deviation 5.285
Change From Baseline in Fixed Flexion Angles at Elbow at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	-0.02 degrees (°) Standard Deviation 16.407	2.80 degrees (°) Standard Deviation 6.842	0.83 degrees (°) Standard Deviation 5.742
Change From Baseline in Fixed Flexion Angles at Elbow at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	-0.03 degrees (°) Standard Deviation 16.659	4.83 degrees (°) Standard Deviation 7.658	0.77 degrees (°) Standard Deviation 10.621
Change From Baseline in Fixed Flexion Angles at Elbow at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	2.78 degrees (°) Standard Deviation 34.075	1.00 degrees (°) Standard Deviation 7.016	-0.08 degrees (°) Standard Deviation 0.825

SECONDARY outcome

Timeframe: Baseline, Month 3, Month 6, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Body Mass Index (BMI) = Weight (kg)/\[(Standing Height (m))\^2\]. Standing height and weight were averaged over a visit before BMI was computed.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Body Mass Index (BMI) at Month 3, Month 6, Month 9, and Month 12 Baseline	19.83 kg/m^2 Standard Deviation 1.022	20.18 kg/m^2 Standard Deviation 1.318	21.57 kg/m^2 Standard Deviation 2.566
Change From Baseline in Body Mass Index (BMI) at Month 3, Month 6, Month 9, and Month 12 Change at Month 3	0.10 kg/m^2 Standard Deviation 0.376	-0.13 kg/m^2 Standard Deviation 0.400	-0.01 kg/m^2 Standard Deviation 0.635
Change From Baseline in Body Mass Index (BMI) at Month 3, Month 6, Month 9, and Month 12 Change at Month 6	0.25 kg/m^2 Standard Deviation 0.547	0.04 kg/m^2 Standard Deviation 0.500	-0.21 kg/m^2 Standard Deviation 0.843
Change From Baseline in Body Mass Index (BMI) at Month 3, Month 6, Month 9, and Month 12 Change at Month 9	0.36 kg/m^2 Standard Deviation 0.565	0.06 kg/m^2 Standard Deviation 0.593	0.02 kg/m^2 Standard Deviation 0.996
Change From Baseline in Body Mass Index (BMI) at Month 3, Month 6, Month 9, and Month 12 Change at Month 12	0.12 kg/m^2 Standard Deviation 0.671	-0.28 kg/m^2 Standard Deviation 0.569	-0.50 kg/m^2 Standard Deviation 0.735

SECONDARY outcome

Timeframe: Baseline, Month 9, and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Waist : Chest Ratio = Waist Circumference / Chest Circumference. Waist and chest circumference were averaged over a visit before waist : chest circumference ratio was computed.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=20 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Waist : Chest Circumference Ratio at Month 9 and Month 12 Baseline	0.93 Ratio Standard Deviation 0.048	0.94 Ratio Standard Deviation 0.051	0.97 Ratio Standard Deviation 0.052
Change From Baseline in Waist : Chest Circumference Ratio at Month 9 and Month 12 Change at Month 9	0.07 Ratio Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	0.00 Ratio Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	-0.01 Ratio Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).
Change From Baseline in Waist : Chest Circumference Ratio at Month 9 and Month 12 Change at Month 12	0.05 Ratio Standard Deviation 0.074	0.00 Ratio Standard Deviation 0.063	-0.01 Ratio Standard Deviation 0.007

SECONDARY outcome

Timeframe: Baseline and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept and with a documented current diagnosis of sleep disordered breathing at enrollment. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

The apnea-hypopnea index (AHI) is the average of the apneic and hypopneic episodes per hour of sleep, which is measured to assess obstructive sleep apnea (OSA). An AHI score of 1 to 4.9 events/hour is mild OSA, 5 to 9.9 events/hour is moderate, and more than 9 events/hour is severe in pediatric population.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=7 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=4 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=8 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Apnea-Hypopnea Index (AHI) at Month 12 Baseline (obstructive AHI)	3.79 events per hour Standard Deviation 4.720	1.20 events per hour Standard Deviation 1.080	6.23 events per hour Standard Deviation 6.881
Change From Baseline in Apnea-Hypopnea Index (AHI) at Month 12 Baseline (total AHI)	6.34 events per hour Standard Deviation 5.837	2.25 events per hour Standard Deviation 2.872	16.07 events per hour Standard Deviation 26.299
Change From Baseline in Apnea-Hypopnea Index (AHI) at Month 12 Change at Month 12 (obstructive AHI)	0.31 events per hour Standard Deviation 9.902	-1.90 events per hour Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	—
Change From Baseline in Apnea-Hypopnea Index (AHI) at Month 12 Change at Month 12 (total AHI)	-1.03 events per hour Standard Deviation 8.671	-2.90 events per hour Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	—

SECONDARY outcome

Timeframe: Baseline and Month 12

Desaturation index is one of the polysomnography parameters to assess obstructive sleep apnea. It refers to the average number of desaturation episodes occurring per hour, where desaturation episodes are defined as a decrease in the mean oxygen saturation of ≥3% (over the last 120 seconds) that lasts for at least 10 seconds.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=7 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=4 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=8 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Desaturation Index at Month 12 Baseline	4.90 desaturations per hour Standard Deviation 8.601	2.18 desaturations per hour Standard Deviation 2.502	13.53 desaturations per hour Standard Deviation 21.364
Change From Baseline in Desaturation Index at Month 12 Change at Month 12	-4.61 desaturations per hour Standard Deviation 14.598	0.20 desaturations per hour Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	—

SECONDARY outcome

Timeframe: Baseline and Month 12

Population: Analysis population included all participants who received at least 1 dose of recifercept and with a documented diagnosis of sleep-disordered breathing at enrollment. The "Number Analyzed" in a row was based on actual analyzed participants at each visit.

Polysomnography refers to a systematic process used to collect physiologic parameters during sleep. Polysomnography other parameters included total sleep time spent with oxygen saturation (SaO2) \< 90% (T90), total sleep time spent with end-tidal carbon dioxide (EtCO2) \>50 mm Hg.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=7 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=4 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=8 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in Polysomnography Other Parameters at Month 12 Baseline (T90)	16.43 percentage (%) of total sleep time Standard Deviation 40.155	24.79 percentage (%) of total sleep time Standard Deviation 49.472	0.72 percentage (%) of total sleep time Standard Deviation 0.758
Change From Baseline in Polysomnography Other Parameters at Month 12 Change at Month 12 (T90)	-48.95 percentage (%) of total sleep time Standard Deviation 69.933	-99.00 percentage (%) of total sleep time Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	—
Change From Baseline in Polysomnography Other Parameters at Month 12 Baseline (EtCO2)	7.02 percentage (%) of total sleep time Standard Deviation 14.030	9.50 percentage (%) of total sleep time Standard Deviation 19.000	7.37 percentage (%) of total sleep time Standard Deviation 17.355
Change From Baseline in Polysomnography Other Parameters at Month 12 Change at Month 12 (EtCO2)	-14.03 percentage (%) of total sleep time Standard Deviation 19.841	-38.00 percentage (%) of total sleep time Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	—

SECONDARY outcome

Timeframe: Baseline and Month 12

SaO2 measures the percentage of oxyhemoglobin (oxygen-bound hemoglobin) in the blood. SaO2 nadir refers to lowest SaO2.

Outcome measures

Outcome measures
Measure	Recifercept 1 mg/kg QW n=7 Participants Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=4 Participants Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=8 Participants Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Change From Baseline in SaO2 Nadir at Month 12 Baseline	92.29 percentage (%) of oxyhemoglobin Standard Deviation 3.147	94.25 percentage (%) of oxyhemoglobin Standard Deviation 6.397	91.06 percentage (%) of oxyhemoglobin Standard Deviation 5.882
Change From Baseline in SaO2 Nadir at Month 12 Change at Month 12	-2.67 percentage (%) of oxyhemoglobin Standard Deviation 7.095	1.00 percentage (%) of oxyhemoglobin Standard Deviation NA No summary statistics were provided for N \<3 considering the insufficient number of participants (only 1 participant analyzed).	—

Adverse Events

Recifercept 1 mg/kg QW

Serious events: 1 serious events

Other events: 16 other events

Deaths: 0 deaths

Recifercept 2 mg/kg BIW

Serious events: 0 serious events

Other events: 19 other events

Deaths: 0 deaths

Recifercept 1.5 mg/kg QD

Serious events: 0 serious events

Other events: 16 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	Recifercept 1 mg/kg QW n=20 participants at risk Children participants were enrolled and randomized to receive recifercept 1 mg/kg once weekly (QW) for 12 months.	Recifercept 2 mg/kg BIW n=19 participants at risk Children participants were enrolled and randomized to receive recifercept 2 mg/kg twice weekly (BIW) for 12 months.	Recifercept 1.5 mg/kg QD n=18 participants at risk Children participants were enrolled and randomized to receive recifercept 1.5 mg/kg once daily (QD) for 12 months.
Cardiac disorders Sinus bradycardia	5.0% 1/20 • Number of events 1 • The first dose up to 28 to 35 days after the last dose of study intervention (13 months).	0.00% 0/19 • The first dose up to 28 to 35 days after the last dose of study intervention (13 months).	0.00% 0/18 • The first dose up to 28 to 35 days after the last dose of study intervention (13 months).

Other adverse events

Additional Information

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Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee Pfizer has the right to review disclosures, requesting a delay of less than 60 days. Investigator will postpone single center publications until after disclosure of pooled data (all sites), less than 12 months from study completion/termination at all participating sites. Investigator may not disclose previously undisclosed confidential information other than study results.
Publication restrictions are in place

Restriction type: OTHER