CompletedNCT03524118Updated Jan 14, 2025Results posted

Safety, Tolerability, and Pharmacokinetics of Clesrovimab (MK-1654) in Infants (MK-1654-002)

A Phase 1/2 interventional study of Clesrovimab and Placebo in Respiratory Tract Infection and Respiratory Syncytial Virus, sponsored by Merck Sharp & Dohme LLC. Completed at 34 sites in 6 countries. Open to participants aged 2 Weeks to 8 Months, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-01-14.

Sponsored by Merck Sharp & Dohme LLC · Phase 1/2, Interventional, and Prevention

Phase: Phase 1/2
Study type: Interventional
Enrollment: 183
Allocation: Randomized
Ages: 2 Weeks to 8 Months
Sex: All

Study summary

The purpose of this study is to evaluate the safety, tolerability, pharmacokinetics, and incidence of anti-drug antibodies (ADAs) of single ascending doses of clesrovimab in healthy pre-term (born at 29 to 35 weeks gestational age) and full-term (born at >35 weeks gestational age) infants. Participants will be randomized into 1 of 4 dose escalation panels (Panels A to D); an additional panel (Panel E) of full-term infants will receive the same dose as Panel D. Key safety and tolerability variables will be reviewed after each dose panel prior to administering the next-highest dose.

Read the detailed description

Participants in Dose Panels A, B, C, D1, and E1 will be followed for up to 365 days. After protocol Amendment 4 (AM4), participants in Dose Panels D2 and E2 will be followed for up to 545 days.

Conditions studied

Respiratory Tract Infection
Respiratory Syncytial Virus

Browse trials for

Respiratory Tract Infections 1,031

In context

Respiratory Tract Infections

1,031 studies on the registry are indexed under Respiratory Tract Infections; 144 are open to participants now.

This study's enrollment of 183 is close to the median of 199 across 698 interventional studies indexed under Respiratory Tract Infections.

Browse Respiratory Tract Infections studies →

Lead sponsor

Merck Sharp & Dohme LLC is the lead sponsor of 2,114 studies on the registry; 133 are open to participants now.

Of its 489 completed or terminated interventional studies of FDA-regulated products, 362 (74%) have results posted.

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 2 Weeks to 8 Months
Sexes eligible: All
Accepts healthy volunteers: Yes

Inclusion criteria

is healthy, based on screening safety laboratory, medical history, and physical examination results
is a pre-term infant (born at 29 weeks to 35 weeks gestational age [inclusive]) or a full-term infant (born at over 35 weeks gestational age), as confirmed in medical records
weighs ≥2 kg at screening

Exclusion criteria

Exclusion Criteria:

has been recommended to receive palivizumab per local standard of care
has ≥1 documented out-of-range safety laboratory results (adjusted for age) at the time of screening
has a known hypersensitivity to any component of the respiratory syncytial virus (RSV) monoclonal antibody
has a history of congenital or acquired immunodeficiency (e.g., splenomegaly)
has documented human immunodeficiency virus (HIV) infection, hepatitis B (HBsAg positive), or hepatitis C (HCV ribonucleic acid [RNA] positive)
has known history of functional or anatomic asplenia
has a diagnosis of failure to thrive within 14 days of screening
has known or history of a coagulation disorder contraindicating intramuscular injection
has received or is expected to receive blood products (except irradiated platelets) within 3 months prior to enrollment
has prior known documented RSV infection
has hemodynamically significant congenital heart disease
has chronic lung disease of prematurity requiring ongoing medical therapy
has a history or current evidence of any condition, therapy, lab abnormality or other circumstance that, in the opinion of the investigator, might expose the participant to undue risk by participating in the study, confound the results of the study, or interfere with the participant's participation for the full duration of the study
has any history of malignancy prior to randomization
if any of the following apply, the Day 1 visit may be rescheduled for a time when these criteria are not met:
has had a recent febrile illness (rectal temperature 38.1°C [100.5°F] or higher or axillary temperature 37.8°C [100.0°F] or higher) within 72 hours pre-dose
is not up-to-date on required vaccinations per local pediatric vaccine schedule at time of screening
has received inactivated or component vaccines (eg, influenza, hepatitis B) less than 14 days pre-dose
has received live, attenuated, non-study licensed pediatric vaccines (e.g., Bacillus Calmette-Guerin vaccine) less than 30 days pre-dose
has received any prior vaccine or monoclonal antibody (mAb) for the prevention of RSV
is currently participating in or has participated in an interventional clinical study with an investigational compound or device at any time prior to first dose administration or while participating in this current study (participants enrolled in observational studies may be included and will be reviewed on a case-by-case basis for approval by the Sponsor)
has enrolled previously in this study and been discontinued
participant's mother participated in a RSV vaccine clinical study while pregnant and participant is ≤3 months of chronological age
is unable to provide blood sample at screening
cannot be adequately followed for safety according to the protocol plan
has a parent/legally acceptable representative who is unlikely to adhere to study procedures, keep appointments, or is planning to relocate during the study
is, or has, an immediate family member (eg, spouse, parent/guardian, sibling, or child) who is directly involved with the study at the site or with the Sponsor

Study design

Phase: Phase 1 / Phase 2
Primary purpose: Prevention
Allocation: Randomized
Intervention model: Sequential assignment
Masking: Triple (Participant, Care provider, Investigator)
Enrollment: 183 participants (actual)

Study arms

Experimental
Panel A: Pre-term clesrovimab Dose 1
Pre-term infants will receive clesrovimab Dose 1 via intramuscular (IM) injection and will be followed for up to 365 days.
Drug: Clesrovimab
Experimental
Panel B: Pre-term clesrovimab Dose 2
Pre-term infants will receive clesrovimab Dose 2 via IM injection and will be followed for up to 365 days.
Drug: Clesrovimab
Experimental
Panel C: Pre-term clesrovimab Dose 3
Pre-term infants will receive clesrovimab Dose 3 via IM injection and will be followed for up to 365 days.
Drug: Clesrovimab
Experimental
Panel D1: Pre-term clesrovimab Dose 4
Pre-term infants enrolled prior to AM4 will receive clesrovimab Dose 4 via IM injection and will be followed for up to 365 days.
Drug: Clesrovimab
Experimental
Panel D2: Pre-term clesrovimab Dose 4
Pre-term infants enrolled after AM4 will receive clesrovimab Dose 4 via IM injection and will be followed for up to 545 days.
Drug: Clesrovimab
Experimental
Panel E1: Full-term clesrovimab Dose 4
Full-term infants enrolled prior to AM4 will receive clesrovimab Dose 4 via IM injection and will be followed for up to 365 days.
Drug: Clesrovimab
Experimental
Panel E2: Full-term clesrovimab Dose 4
Full-term infants enrolled after AM4 will receive clesrovimab Dose 4 via IM injection and will be followed for up to 545 days.
Drug: Clesrovimab
Placebo comparator
Placebo
Pre-term infants will receive placebo via IM injection.
Drug: Placebo

Interventions

DrugClesrovimab
Single ascending doses of clesrovimab will be administered via IM injection.
Also known as: MK-1654
DrugPlacebo
Placebo (0.9% sodium chloride \[NaCl\]) will be administered via IM injection.

What researchers measure

Primary outcomes

Percentage of Participants Who Experienced At Least One Solicited Injection Site Adverse Event (AE)
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Solicited injection site AEs were monitored from Day 1 to Day 5.
Time frame: Up to Day 5
Percentage of Participants Who Experienced At Least One Solicited Systemic Adverse Event (AE)
An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Solicited systemic AEs were monitored from Day 1 to Day 5.
Time frame: Up to Day 5
Percentage of Participants Who Experienced At Least One Serious Adverse Event (SAE)
An SAE is any untoward medical occurrence that, at any dose, results in death; is life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization; results in persistent or significant injury/incapacity; is a congenital anomaly/birth defect; or is an other important medical event.
Time frame: Up to Day 545

Secondary outcomes

Area Under the Serum-Concentration Time Curve From Zero to Infinity (AUC0-∞)
AUC0-∞ is a measure of the extrapolated mean concentration in serum from dosing to infinity.
Time frame: At designated time points (up to 1 year post-dose)
Maximum Serum Concentration (Cmax) of Clesrovimab
Cmax is the highest observed serum drug concentration.
Time frame: At designated time points (up to 1 year post-dose)
Time to Maximum Serum Concentration (Tmax) of Clesrovimab
Tmax is the time taken to reach the maximum observed plasma (Cmax) concentration of Clesrovimab.
Time frame: At designated time points (up to 1 year post-dose)
Apparent Terminal Half-life (t1/2) of Clesrovimab
t1/2 is the time required for 50% of drug to be cleared from serum.
Time frame: At designated time points (up to 1 year post-dose)
Serum Concentration of Clesrovimab on Day 7 (C7days)
Serum concentration of clesrovimab was measured on Day 7.
Time frame: Day 7
Serum Concentration of Clesrovimab on Day 14 (C14days)
Serum concentration of clesrovimab was measured on Day 14.
Time frame: Day 14
Serum Concentration of Clesrovimab on Day 90 (C90days)
Serum concentration of clesrovimab was measured on Day 90.
Time frame: Day 90
Serum Concentration of Clesrovimab on Day 150 (C150days)
Serum concentration of clesrovimab was measured on Day 150.
Time frame: Day 150
Serum Concentration of Clesrovimab on Day 365 (C365days)
Serum concentration of clesrovimab was measured on Day 365.
Time frame: Day 365
Number of Participants With Positive Titer of Anti-Drug Antibodies (ADAs) for Clesrovimab: Panels A, B, C, D1, D2, E1, and E2
ADA was assessed at 2 or 3 of the following timepoints for each participant: Days 14, 90, 150, 365 and 545. ADA status for each participant was determined across the timepoints assessed. The definitions of the categories are as follows: (1) ADA Negative: participants whose ADA results were negative at all timepoints measured; (2) Non-treatment emergent positive: participants whose ADA result was positive only at baseline or if postdose titer increased by less than 2-fold relative to the baseline titer; (3) Positive response to MK-1654: participants whose ADA result was negative at baseline and positive at one or more postdose timepoints or participants whose ADA result was positive at baseline and postdose titer increased by greater than or equal to 2-fold relative to the baseline titer.
Time frame: Days 14, 90, 150, 365 and 545

Results

Posted Nov 29, 2023

Participant flow

183 participants were randomized and 181 were dosed and included in the All Participants as Treated (APaT) population. Two participants who were randomized to the MK-1654 20 mg dose group actually received MK-1654 50 mg and were included in the MK-1654 50 mg group for safety, pharmacokinetic (PK) and immunogenicity analyses.

Participant flow — Overall Study
Milestone	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo
Started	8	31	41	32	33	38
Treated	8	31	40	32	32	38
Safety analysis population	6	33	40	32	32	38
Completed	8	29	40	31	26	37
Not completed	0	2	1	1	7	1
Withdrew: Lost to follow-up	0	0	0	0	1	0
Withdrew: Other	0	1	0	0	1	1
Withdrew: Physician decision	0	0	0	0	1	0
Withdrew: Protocol violation	0	0	1	0	1	0
Withdrew: Withdrawal by parent/guardian	0	1	0	1	3	0

Outcome measures

PrimaryPercentage of Participants Who Experienced At Least One Solicited Injection Site Adverse Event (AE)

An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Solicited injection site AEs were monitored from Day 1 to Day 5.

Time frame:: Up to Day 5
Reported as:: Count of participants · Participants

Percentage of Participants Who Experienced At Least One Solicited Injection Site Adverse Event (AE)
Participants	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo
with solicited injection site adverse events	3	3	3	2	2	2
without solicited injection site adverse events	3	30	37	30	30	36

PrimaryPercentage of Participants Who Experienced At Least One Solicited Systemic Adverse Event (AE)

Time frame:: Up to Day 5
Reported as:: Count of participants · Participants

Percentage of Participants Who Experienced At Least One Solicited Systemic Adverse Event (AE)
Participants	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo
with solicited systemic adverse events	2	8	9	2	3	9
without solicited systemic adverse events	4	25	31	30	29	29

PrimaryPercentage of Participants Who Experienced At Least One Serious Adverse Event (SAE)

An SAE is any untoward medical occurrence that, at any dose, results in death; is life-threatening; requires inpatient hospitalization or prolongation of existing hospitalization; results in persistent or significant injury/incapacity; is a congenital anomaly/birth defect; or is an other important medical event.

Time frame:: Up to Day 545
Reported as:: Count of participants · Participants

Percentage of Participants Who Experienced At Least One Serious Adverse Event (SAE)
Participants	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo
with serious adverse events (SAE)	1	4	1	3	6	6
without SAE	5	29	39	29	26	32

SecondaryArea Under the Serum-Concentration Time Curve From Zero to Infinity (AUC0-∞)

AUC0-∞ is a measure of the extrapolated mean concentration in serum from dosing to infinity.

Time frame:: At designated time points (up to 1 year post-dose)
Reported as:: Geometric mean · day*μg/mL

Area Under the Serum-Concentration Time Curve From Zero to Infinity (AUC0-∞)
day*μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Area Under the Serum-Concentration Time Curve From Zero to Infinity (AUC0-∞)	1560 ± 43.5	3520 ± 22.8	5510 ± 22.4	6790 ± 25.4	5690 ± 15.9

SecondaryMaximum Serum Concentration (Cmax) of Clesrovimab

Cmax is the highest observed serum drug concentration.

Time frame:: At designated time points (up to 1 year post-dose)
Reported as:: Geometric mean · μg/mL

Maximum Serum Concentration (Cmax) of Clesrovimab
μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Maximum Serum Concentration (Cmax) of Clesrovimab	26.3 ± 19.3	61.7 ± 21.8	94.5 ± 20.5	117 ± 23.5	99.9 ± 13.7

SecondaryTime to Maximum Serum Concentration (Tmax) of Clesrovimab

Tmax is the time taken to reach the maximum observed plasma (Cmax) concentration of Clesrovimab.

Time frame:: At designated time points (up to 1 year post-dose)
Reported as:: Median · day

Time to Maximum Serum Concentration (Tmax) of Clesrovimab
day	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Time to Maximum Serum Concentration (Tmax) of Clesrovimab	4.0 (3.8 to 4.60)	4.20 (3.70 to 5.30)	4.20 (3.00 to 5.80)	4.10 (3.70 to 6.00)	4.10 (3.70 to 4.90)

SecondaryApparent Terminal Half-life (t1/2) of Clesrovimab

t1/2 is the time required for 50% of drug to be cleared from serum.

Time frame:: At designated time points (up to 1 year post-dose)
Reported as:: Geometric mean · day

Apparent Terminal Half-life (t1/2) of Clesrovimab
day	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Apparent Terminal Half-life (t1/2) of Clesrovimab	48.8 ± 34.6	44.6 ± 10.9	46.1 ± 15.1	45.2 ± 13.7	43.0 ± 9.72

SecondarySerum Concentration of Clesrovimab on Day 7 (C7days)

Serum concentration of clesrovimab was measured on Day 7.

Time frame:: Day 7
Reported as:: Geometric mean · μg/mL

Serum Concentration of Clesrovimab on Day 7 (C7days)
μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Serum Concentration of Clesrovimab on Day 7 (C7days)	24.4 ± 20.4	57.8 ± 21.6	88.1 ± 20.4	109 ± 23.0	92.8 ± 13.3

SecondarySerum Concentration of Clesrovimab on Day 14 (C14days)

Serum concentration of clesrovimab was measured on Day 14.

Time frame:: Day 14
Reported as:: Geometric mean · μg/mL

Serum Concentration of Clesrovimab on Day 14 (C14days)
μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Serum Concentration of Clesrovimab on Day 14 (C14days)	19.4 ± 22.1	46.8 ± 20.6	71.1 ± 19.7	88.6 ± 21.8	75.4 ± 12.9

SecondarySerum Concentration of Clesrovimab on Day 90 (C90days)

Serum concentration of clesrovimab was measured on Day 90.

Time frame:: Day 90
Reported as:: Geometric mean · μg/mL

Serum Concentration of Clesrovimab on Day 90 (C90days)
μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Serum Concentration of Clesrovimab on Day 90 (C90days)	5.60 ± 49.5	13.0 ± 25.4	20.4 ± 25.8	25.2 ± 28.6	21.1 ± 18.8

SecondarySerum Concentration of Clesrovimab on Day 150 (C150days)

Serum concentration of clesrovimab was measured on Day 150.

Time frame:: Day 150
Reported as:: Geometric mean · μg/mL

Serum Concentration of Clesrovimab on Day 150 (C150days)
μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Serum Concentration of Clesrovimab on Day 150 (C150days)	2.24 ± 80.6	4.98 ± 34.2	8.05 ± 37.7	9.70 ± 40.2	7.96 ± 26.7

SecondarySerum Concentration of Clesrovimab on Day 365 (C365days)

Serum concentration of clesrovimab was measured on Day 365.

Time frame:: Day 365
Reported as:: Geometric mean · μg/mL

Serum Concentration of Clesrovimab on Day 365 (C365days)
μg/mL	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
Serum Concentration of Clesrovimab on Day 365 (C365days)	0.0953 ± 362	0.177 ± 79.4	0.313 ± 107	0.355 ± 104	0.248 ± 63.1

SecondaryNumber of Participants With Positive Titer of Anti-Drug Antibodies (ADAs) for Clesrovimab: Panels A, B, C, D1, D2, E1, and E2

ADA was assessed at 2 or 3 of the following timepoints for each participant: Days 14, 90, 150, 365 and 545. ADA status for each participant was determined across the timepoints assessed. The definitions of the categories are as follows: (1) ADA Negative: participants whose ADA results were negative at all timepoints measured; (2) Non-treatment emergent positive: participants whose ADA result was positive only at baseline or if postdose titer increased by less than 2-fold relative to the baseline titer; (3) Positive response to MK-1654: participants whose ADA result was negative at baseline and positive at one or more postdose timepoints or participants whose ADA result was positive at baseline and postdose titer increased by greater than or equal to 2-fold relative to the baseline titer.

Time frame:: Days 14, 90, 150, 365 and 545
Reported as:: Count of participants · Participants

Number of Participants With Positive Titer of Anti-Drug Antibodies (ADAs) for Clesrovimab: Panels A, B, C, D1, D2, E1, and E2
Participants	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg
ADA Negative status	4	23	35	15	9
Non-treatment emergent positive	0	0	0	1	1
ADA Positive response to MK-1654	2	9	4	16	20
Maximum Postdose Titer of 20 to < 189 of ADA	0	6	2	4	2
Maximum Postdose Titer of 189 to < 1077.5 of ADA	0	1	1	3	7
Maximum Postdose Titer of 1077.5 to < 9285 of ADA	0	0	1	4	7
Maximum Postdose Titer of 9285 to 160000 of ADA	2	2	0	4	4

Adverse events

Collected over Up to Day 545. Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
Group	Deaths	Serious	Other
MK-1654 20 mg in Pre-term Infants	0/8 (0%)	1/6 (16.7%)	6/6 (100%)
MK-1654 50 mg in Pre-term Infants	0/31 (0%)	4/33 (12.1%)	29/33 (87.9%)
MK-1654 75 mg in Pre-term Infants	0/41 (0%)	1/40 (2.5%)	29/40 (72.5%)
MK-1654 100 mg Pre-Term Infants	0/32 (0%)	3/32 (9.4%)	26/32 (81.3%)
MK-1654 100 mg Full-Term Infants	0/33 (0%)	6/32 (18.8%)	29/32 (90.6%)
Placebo	0/38 (0%)	6/38 (15.8%)	33/38 (86.8%)

Most frequent serious events

Showing 10 of 15

Most frequent serious events
Event	MK-1654 20 mg in Pre-term Infants	MK-1654 50 mg in Pre-term Infants	MK-1654 75 mg in Pre-term Infants	MK-1654 100 mg Pre-Term Infants	MK-1654 100 mg Full-Term Infants	Placebo
BronchiolitisInfections and infestations	1/6	0/33	0/40	0/32	0/32	2/38
PneumoniaInfections and infestations	1/6	0/33	0/40	0/32	2/32	0/38
Respiratory syncytial virus bronchiolitisInfections and infestations	0/6	1/33	0/40	0/32	0/32	3/38
Biliary cystHepatobiliary disorders	0/6	0/33	0/40	0/32	1/32	0/38
COVID-19Infections and infestations	0/6	0/33	0/40	1/32	0/32	0/38
CellulitisInfections and infestations	0/6	0/33	0/40	1/32	0/32	0/38
Croup infectiousInfections and infestations	0/6	0/33	0/40	0/32	1/32	0/38
GastroenteritisInfections and infestations	0/6	1/33	0/40	0/32	1/32	0/38
Respiratory syncytial virus infectionInfections and infestations	0/6	0/33	0/40	1/32	1/32	0/38
Rhinovirus infectionInfections and infestations	0/6	0/33	0/40	0/32	1/32	0/38

Most frequent other events

Showing 10 of 38

Most frequent other events
Event	MK-1654 20 mg in Pre-term Infants	MK-1654 50 mg in Pre-term Infants	MK-1654 75 mg in Pre-term Infants	MK-1654 100 mg Pre-Term Infants	MK-1654 100 mg Full-Term Infants	Placebo
Upper respiratory tract infectionInfections and infestations	2/6	17/33	7/40	12/32	18/32	12/38
Injection site painGeneral disorders	2/6	0/33	2/40	2/32	0/32	1/38
Injection site swellingGeneral disorders	2/6	1/33	0/40	0/32	1/32	1/38
BronchiolitisInfections and infestations	2/6	2/33	4/40	7/32	5/32	5/38
IrritabilityPsychiatric disorders	2/6	7/33	5/40	2/32	2/32	9/38
Nasal congestionRespiratory, thoracic and mediastinal disorders	2/6	5/33	2/40	6/32	8/32	5/38
NasopharyngitisInfections and infestations	1/6	2/33	11/40	10/32	10/32	7/38
GastroenteritisInfections and infestations	0/6	1/33	0/40	1/32	6/32	0/38
ConstipationGastrointestinal disorders	1/6	0/33	0/40	0/32	2/32	0/38
Injection site erythemaGeneral disorders	1/6	2/33	1/40	1/32	1/32	1/38

Baseline characteristics

Age, Continuous
Age, Continuous(days)	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo	Total
Median	68.0 (31 to 257)	109.0 (23 to 255)	94.0 (24 to 245)	139.5 (14 to 239)	164.0 (46 to 250)	128.0 (26 to 275)	126.0 (14.0 to 275)

Age, Customized
Age, Customized(Participants)	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo	Total
In utero	0	0	0	0	0	0	0
Preterm newborn infants (gestational age < 37 wks)	0	0	0	0	0	0	0
Newborns (0-27 days)	0	2	3	3	0	2	10
Infants and toddlers (28 days-23 months)	8	29	38	29	33	36	173
Children (2-11 years)	0	0	0	0	0	0	0
Adolescents (12-17 years)	0	0	0	0	0	0	0
Adults (18-64 years)	0	0	0	0	0	0	0
From 65-84 years	0	0	0	0	0	0	0
85 years and over	0	0	0	0	0	0	0

Sex: Female, Male
Sex: Female, Male(Participants)	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo	Total
Female	6	15	20	17	13	19	90
Male	2	16	21	15	20	19	93

Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo	Total
Hispanic or Latino	1	12	25	9	14	18	79
Not Hispanic or Latino	7	19	16	23	19	20	104
Unknown or Not Reported	0	0	0	0	0	0	0

Race (NIH/OMB)
Race (NIH/OMB)(Participants)	Panel A: Preterm Clesrovimab 20mg	Panel B: Pre-term Clesrovimab 50mg	Panel C: Pre-term Clesrovimab 75mg	Panel D1 and D2: Pre-term Clesrovimab 100mg	Panel E1 and E2: Full-term Clesrovimab 100mg	Placebo	Total
American Indian or Alaska Native	0	0	1	1	1	2	5
Asian	0	1	0	5	0	0	6
Native Hawaiian or Other Pacific Islander	0	0	0	0	0	0	0
Black or African American	4	8	9	14	14	11	60
White	4	20	14	8	11	14	71
More than one race	0	1	17	2	7	9	36
Unknown or Not Reported	0	1	0	2	0	2	5

Study locations

34 sites

Children's Hospital - Colorado ( Site 0067)
Aurora, Colorado 80045, United States
Next Phase Research Alliance, LLC ( Site 0075)
Homestead, Florida 33030, United States
Acevedo Clinical Research Associates ( Site 0025)
Miami, Florida 33142, United States
Kapiolani Medical Center for Women and Children ( Site 0027)
Honolulu, Hawaii 96826, United States
Cotton-O'Neil Clinical Research Center PediatricCare ( Site 0081)
Topeka, Kansas 66604, United States
Children's Mercy Hospital ( Site 0037)
Kansas City, Missouri 64108, United States
Dartmouth-Hitchcock Medical Center ( Site 0032)
Lebanon, New Hampshire 03766, United States
SUNY Upstate Medical University Hospital ( Site 0029)
Syracuse, New York 13210, United States
WakeMed Health and Hospitals ( Site 0033)
Raleigh, North Carolina 27610, United States
Cincinnati Children's Hospital Medical Center ( Site 0031)
Cincinnati, Ohio 45229, United States
Ohio Pediatric Research Association ( Site 0066)
Dayton, Ohio 45414, United States
Coastal Pediatric Research ( Site 0028)
Charleston, South Carolina 29414, United States
Tribe Clinical Research, LLC ( Site 0082)
Greenville, South Carolina 29607, United States
University of Texas Medical Branch at Galveston ( Site 0039)
Galveston, Texas 77555, United States
Tekton Research, Inc. ( Site 0026)
San Antonio, Texas 78240, United States
Multicare Institute For Research And Innovation ( Site 0035)
Tacoma, Washington 98405, United States
University of Wisconsin American Family Children's Hospital ( Site 0068)
Madison, Wisconsin 53792, United States
Centro de Investigacion Clinica Bradford Hill ( Site 0103)
Santiago, Region M. De Santiago 7650698, Chile
Hospital La Florida ( Site 0050)
Santiago, Region M. De Santiago 8242238, Chile
Facultad Medicina Universidad de Chile ( Site 0104)
Santiago, Region M. De Santiago 8380453, Chile
Hospital Padre Hurtado ( Site 0102)
Santiago, Region M. De Santiago 8880465, Chile
Fundacion Hospital San Vicente de Paul ( Site 0097)
Medellin, Antioquia 050010, Colombia
Universidad Pontificia Bolivariana - Clinica Universitaria Bolivariana ( Site 0098)
Medellin, Antioquia 050036, Colombia
Centro de Atención e Investigación Médica SAS - CAIMED CHIA ( Site 0100)
Chia, Cundinamarca 250001, Colombia
MedPlus Medicina Prepagada S.A. ( Site 0095)
Bogota, Distrito Capital De Bogota 110221, Colombia
Fundacion Universitaria de Ciencias de la Salud - Sociedad de Cirugia ( Site 0099)
Bogota, Distrito Capital De Bogota 111411, Colombia
Fundacion Valle del Lili ( Site 0090)
Cali, Valle Del Cauca 760032, Colombia
Seoul National University Hospital ( Site 0071)
Seoul, 03080, Korea, Republic of
Severance Hospital Yonsei University Health System ( Site 0073)
Seoul, 03722, Korea, Republic of
Samsung Medical Center ( Site 0072)
Seoul, 06351, Korea, Republic of
Chris Hani Baragwanath Academic Hospital ( Site 0262)
Johannesburg, Gauteng 2013, South Africa
Tygerberg Hospital ( Site 0261)
Cape Town, Western Cape 7505, South Africa
Hospital Clinico Universitario de Santiago ( Site 0241)
Santiago de Compostela, La Coruna 15706, Spain
Hospital Universitario La Paz ( Site 0242)
Madrid, 28046, Spain

References and documents

Publications

Madhi SA, Simoes EAF, Acevedo A, Novoa Pizarro JM, Shepard JS, Railkar RA, Cao X, Maas BM, Zang X, Krick A, Roadcap B, Vora KA, Aliprantis AO, Lee AW, Sinha A. A Phase 1b/2a Trial of a Half-life Extended Respiratory Syncytial Virus Neutralizing Antibody, Clesrovimab, in Healthy Preterm and Full-term Infants. J Infect Dis. 2025 Mar 17;231(3):e478-e487. doi: 10.1093/infdis/jiae581. PubMed 39601265 ↗
Thambi N, Phuah JY, Staupe RP, Tobias LM, Cao Y, McKelvey T, Railkar RA, Aliprantis AO, Arriola CS, Maas BM, Vora KA. Development of High-Titer Antidrug Antibodies in a Phase 1b/2a Infant Clesrovimab Trial Are Associated With RSV Exposure Beyond Day 150. J Infect Dis. 2025 Mar 17;231(3):e488-e496. doi: 10.1093/infdis/jiae582. PubMed 39590882 ↗

Study documents

Protocol and statistical analysis plan · Jul 30, 2020

Documents are hosted by the registry — open the source record to download them.

Individual participant data

Plan to share: Yes — http://engagezone.msd.com/doc/ProcedureAccessClinicalTrialData.pdf

Updates

Tracking since Sep 25, 2026

No changes since tracking began. The registry record was last updated on Jan 14, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT03524118
Lead sponsor: Merck Sharp & Dohme LLC
Responsible party: Sponsor
First posted: May 14, 2018
Start date: Sep 20, 2018
Primary completion: Sep 14, 2022
Completion: Sep 14, 2022
Results posted: Nov 29, 2023
Last update: Jan 14, 2025

Study contacts

Medical Director

study director · Merck Sharp & Dohme LLC

Oversight

Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

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