02 RSV Mat Peds Sinha 508

CDC ACIP — Vaccine Advisory Committee

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Clesrovimab  (MK-1654): 
Pediatric  Clinical  Program
Presentation  to the Advisory  Committee  on Immunization  Practices
Anushua  Sinha,  MD, MPH
Clinical  Director  -Vaccines  Clinical  Research 
Merck  & Co., Inc.
Rahway,  NJ, USA
October  23, 2024
Confidential
Clesrovimab  is a human  monoclonal  antibody  with four unique  molecular 
characteristics  that enable  robust  and durable  protection  from  RSV
2Notes: a. Clesrovimab  is ~50-fold more  potent  in vitro than palivizumab;  Abbreviations : F=Fusion;  RSV=Respiratory  Syncytial  Virus;  Sources : 1. Tang  A et al. Nat Commun . 2019;  2. RSV GeneBank  sequences 
as of April 1, 2024;  3. Phuah  JY et al. Biomed  Pharmacother.  2023.
ClesrovimabRSV Prefusion  F protein
Site IVBinds  with high affinity  to site IV of RSV  F protein,  
prevents  fusion  of virus  to host cells  and blocks  entry  to 
provide  direct  protection1
̶  Binding  epitope  on site IV is highly  conserved , with 99.8% identity  
among  >15,000 reported  RSV-A and RSV-B sequences2
High  potency  in vitro and equipotent  against  RSV-A and RSV-Ba
YTE substitutions  enable  extended  half-life (~44  days)
4
Achieves  high nasal  tissue  distribution  and concentrations  at sites 
of RSV infection32
31
Site IV
Clesrovimab
Confidential
➢Prevention  of respiratory  syncytial  virus  (RSV)  lower  respiratory  tract 
disease  in neonates  and infants  who are born  during  or entering  their  first 
RSV seasonProposed  Indication  and Dosing
3Proposed  Indication
➢105 mg/0.7  mL administered  as a single  intramuscular (IM)  injection
➢Clesrovimab  dosing  is the same  for all infants  regardless  of weightProposed  Dosing  and 
Administration
Confidential
Clesrovimab  Clinical  Development  Program
4
Phase  1:
Safety  and PK – adults
Phase  1b/2a:
Safety  and PK – infants
Phase  2b/3:
Efficacy,  safety  and PK – 
infants  & childrenPhase  1 – Adults
(Protocol  001)1
Completed
Phase  1b/2a – Infants  (Protocol  002)3
Completed
2017 2018 2019 2020 2021 2022 2023Currently 
here
Abbreviations:  PK=Pharmacokinetics;  RSV=Respiratory  Syncytial  Virus;  Sources:  1. Aliprantis  AO et al. Clin Pharmacol  Drug  Dev. 2021;10(5):556 -566; 2. Orito Y et al. Clin Transl  Sci. 2022;15(7):1753 -1763;
3. Madhi  SA, Simoes  EAF,  Acevedo  A, et al. A phase  1b/2a  single -ascending -dose  study  to evaluate  the safety,  tolerability,  and pharmacokinetics  of an RSV-neutralizing  antibody,  clesrovimab,  in preterm 
and full-term  infants.  Oral and Poster  presentation.  8th ReSViNET  Conference  February  13-16, 2024  Mumbai,  India;  4. clinicaltrials.gov  (NCT04767373);  5. clinicaltrials.gov  (NCT04938830).Phase  1 – Adults
(Protocol  003)2
CompletedPhase  1 – Adults,  Infants 
& Children  (Protocol  008)
Completed
Phase  2b/3  – Infants  (Protocol  004)4
Completed
Phase  3 – Infants  & Children (Protocol  007)5
Ongoing
2024

Protocol  004:
A Phase  2b/3 Double -Blind,  Randomized,  Placebo -Controlled 
Study  to Evaluate  the Efficacy  and Safety  of Clesrovimab  in 
Healthy  Preterm  and Full-Term  Infants
Confidential
Protocol  004:  Study  Design
Phase  2b/3 randomized,  double -blinded,  placebo -controlled  with active RSV surveillance  through  6 months
Objective:  Efficacy  and safety  of clesrovimab  in healthy  preterm  and full-term  infants  entering  their  first RSV season
▪Phase  2b cohort : First  300 infants  enrolled
▪Phase  3 cohort : Seamless  enrollment  following  Phase  2b cohort
Experimental  Arm
Comparator  ArmRSV-Associated  Efficacy
•MALRI ≥  1 Indicator of LRI/Severity  (primary)
•Hospitalization  (secondary)
•Acute  Respiratory  Infection (ARI)b (tertiary)
•Lower  Respiratory  Infection  Hospitalization 
(tertiary)
•Severe  MALRIc (tertiary)
•MALRI  ≥ 2 Indicators  of LRI/Severity  (post -hoc)
Safety
•Adverse  Events  (AEs)
•Serious  Adverse  Events  (SAEs)
Placebo
0.9%  NaCl
(N = 1,203)
Clesrovimab
105 mg Single  IM dose 
(N = 2,411)
Randomization 
2:1
(N = 3,614)aAll RSV-Associated  
Efficacy  Endpoints  
followed  through  6 
months  postdosedDay 1At Month  6 At Month  5
Notes : a. N=Number  of randomized  participants,  dosed  with clesrovimab  or placebo ; b. ARI: Includes  both upper  and lower  respiratory  tract  infection ; c. Severe  MALRI : Severe  hypoxemia  (SpO 2 <90% on 
room  air at sea level; <87% on room  air at altitude  ≥1800  m) or the need  for high flow nasal  cannula,  oxygen  mask,  or mechanical  ventilatory  support ; d. 6 month  endpoints  have  the same  designation  as 5 
month  endpoints  aside  from  Hospitalization  through  6 months,  which  is a tertiary  endpoint,  and MALRI  ≥ 1 indicator  of LRI/Severity,  which  is a secondary  endpoint ; Abbreviations : ARI=Acute  Respiratory  
Infection ; IM=Intramuscular ; LRI=Lower  Respiratory  Tract  Infection ; MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection ; NaCl=Sodium  Chloride ; RSV=Respiratory  Syncytial  Virus .6First 1,650  infants 
enrolled  planned  for 
follow -up through 
Day 515 postdose 
(second  RSV season)
Confidential
Protocol  004:  Baseline  Characteristics
7Clesrovimab 
N = 2,411Placebo 
N = 1,203
Participants n (%) n (%)
Age at Randomization  (Months)
<6 1,923 (79.8) 964 (80.1)
≥6 to <9 383 (15.9) 192 (16.0)
≥9 105 (4.4) 47 (3.9)
Mean  (SD) 3.7 (2.6) 3.7 (2.6)
Median  (Range) 3.0 (0 to 12) 3.1 (0 to 12)
Body  Weight  at Randomization  (kg)
Mean  (SD) 5.8 (2.0) 5.9 (2.0)
Median  (Range) 5.8 (1.6 to 11.9) 5.8 (1.6 to 11.6)
Gestational  Age
Early and Moderate  Preterm  Infant  (≥29 to <35 weeks) 422 (17.5) 209 (17.4)
Late Preterm  and Full-term  Infant  (≥35 weeks) 1,989 (82.5) 994 (82.6)
Race
American  Indian  Or Alaska  Native 50 (2.1) 18 (1.5)
Asian 641 (26.6) 320 (26.6)
Black  Or African  American 326 (13.5) 171 (14.2)
Multiple 302 (12.5) 138 (11.5)
Native  Hawaiian  Or Other  Pacific  Islander 1 (0.0) 1 (0.1)
White 1,082 (44.9) 550 (45.7)
Missinga 9 (0.4) 5 (0.4)
Ethnicity
Hispanic  Or Latino 682 (28.3) 335 (27.8)
Not Hispanic  Or Latino 1,660 (68.9) 834 (69.3)
Not Reported,  Unknown,  or Missing 69 (2.9) 34 (2.8)
Sex
Male 1,228 (50.9) 617 (51.3)
Female 1,183 (49.1) 586 (48.7)
Note:  a. Includes  8 participants from  South  Africa  who have  race reported  as "Colored"  which  is not a standard  category  on the form;  Abbreviation: SD=Standard  Deviation.•Baseline  characteristics  of 
infants  were  similar  in both 
clesrovimab  and placebo 
arms
•A total  of 3,614  healthy 
infants  were  dosed
•2,411  infants  received 
clesrovimab  and 1,203 
infants  received  placebo
•Enrolled  a diverse 
population  across  race and 
ethnicity  from  22
countries,  across  5 
continents
•631 participants  were 
preterm  infants  (≥29 to
<35 weeks)
•2,983  were  full-term 
infants  (≥35 weeks)
Confidential
RSV-Associated  Endpointa
(Through  5 months)Endpoint 
DesignationEfficacy  through  5 months
Clesrovimab 
(n = 2,398)Placebo 
(n = 1,201)Observed  Efficacy
%, (95%  CI)
# of Cases # of Cases
Severe  MALRI Tertiary 2 12 91.7 (62.9,  98.1)
LRI Hospitalization Tertiary 5 27 90.9  (76.2,  96.5)
Hospitalization Secondary 9 28 84.2d (66.6,  92.6)
MALRI  requiring  ≥ 2 Indicators  of 
LRI/Severityb Post -Hoc 10 41 88.0  (76.1,  94.0)
MALRI  requiring  ≥ 1 Indicator  of 
LRI/SeverityPrimary 60 74 60.4c (44.1,  71.9)
Acute  Respiratory  Infection  (ARI) Tertiary 148 148 52.0 (39.5,  61.9)Protocol  004:  Efficacy
Single  dose of clesrovimab  protects  healthy  preterm  and full-term infants  against  mild,  moderate,  and severe  RSV 
disease  through  5 months
8Notes:  a. ARI and MALRI  include  both inpatient  and outpatient  cases;  b. MALRI  requiring  ≥ 2 indicators  of LRI/severity  endpoint  is most  comparable  to nirsevimab’s  primary  endpoint  in the MELODY  trial;
c. Primary  endpoint,  p<0.001  (criterion=lower  bound  of the 95% CI >25%);  d. Secondary  endpoint,  p<0.001  (criterion=lower  bound  of the 95% CI >0%);  Abbreviations:  ARI=Acute  Respiratory  Infection; 
LRI=Lower  Respiratory Tract  Infection;  MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection.Increasing  Disease  Severity

Confidential
RSV-Associated  Endpointa
(Through  6 months )Endpoint 
DesignationEfficacy  through  6 months
Clesrovimab 
(n = 2,398)Placebo 
(n = 1,201)Observed  Efficacy
%, (95%  CI)
# of Cases # of Cases
Severe  MALRI Tertiary 2 12 91.7 (62.9,  98.1)
LRI Hospitalization Tertiary 5 28 91.2 (77.2,  96.6)
Hospitalization Tertiary 11 29 81.3 (62.5,  90.7)
MALRI  requiring  ≥ 2 Indicators  of 
LRI/Severityb Post -Hoc 11 42 87.2 (75.1,  93.4)
MALRI  requiring  ≥ 1 Indicator  of 
LRI/SeveritySecondary 64 77 59.5 (43.3,  71.1)
Acute  Respiratory  Infection  (ARI) Tertiary 161 154 50.0  (37.4,  60.1)Protocol  004:  Efficacy
Durable  across  all endpoints  through  6 months
9Notes:  a. ARI and MALRI  include  both inpatient  and outpatient  cases;  b. MALRI  requiring  ≥ 2 indicators  of LRI/severity  endpoint  is most  comparable  to nirsevimab’s  primary  endpoint  in the MELODY  trial;
Abbreviations:  ARI=Acute  Respiratory  Infection;  LRI=Lower  Respiratory  Tract  Infection;  MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection.Increasing  Disease  Severity

Confidential
Protocol  004:  All-Cause  Endpoints
10All-cause  Endpoint 
(Through  5 months 
Postdose)Clesrovimab 
(N = 2,411)Placebo 
(N = 1,203)Observed  Efficacy 
(%) Estimate  
(95% CI)c
nNumber 
of EventsTotal  Follow - 
Up Time 
(months)aIncidence 
Rate  Over  5 
monthsb, %nNumber 
of EventsTotal  Follow - 
Up Time 
(months)aIncidence 
Rate  over 5 
monthsb, %
Outpatient  and 
Inpatient  MALRI 
due to any cause2,398 526 10,349.2 25.4 1,201 296 5,063.8 29.213.1
(-0.6; 24.8)
LRI Hospitalization 
due to any cause2,398 60 11,711.8 2.6 1,201 58 5,774.0 5.049.0
(26.7, 64.5)
Notes:  a. One month  is defined  as 30 days  for the total follow -up time calculation;  b. Five months  is defined  as 150 days;  c. Estimate  and 95% CI of efficacy  were  estimated  from the modified  Poisson 
regression  with robust  variance  method;  Every  participant  is counted  a single  time for each applicable  endpoint  category;  A participant  may appear  in more  than one endpoint  category;  For each 
participant,  only the first occurrence  of the case for each endpoint  category  is counted  for the analysis;  N=Number  of participants  randomized  and dosed  with clesrovimab  or placebo;  n=Number  of 
participants  eligible  for inclusion  in the full analysis  set population;  Abbreviations:  CI=Confidence  Interval;  LRI=Lower  Respiratory  Tract  Infection;  MALRI=Medically -Attended  Lower  Respiratory  
Tract  Infection.
ConfidentialConfidential
Protocol  004:  Safety
Well-tolerated  in healthy  preterm  and full-term infants  with a safety  profile  that is generally  comparable  to placebo
11Participants  with AEsClesrovimab 
Na = 2,409Placebo 
Na = 1,202
n (%) n (%)
Overall  Solicited and Unsolicited  AEs (Days  1-365 postdose)
≥ 1 AE 1,816  (75.4) 918 (76.4)
Drug -related  AE 587 (24.4) 296 (24.6)
Any SAE 278 (11.5) 149 (12.4)
Drug -related  SAEb 1 (0.0) 1 (0.1)
Deathc 7 (0.3) 3 (0.2)
Solicited  AEs (Days  1-5 postdose)
Injection  site pain 122 (5.1) 77 (6.4)
Injection  site erythema 90 (3.7) 40 (3.3)
Injection  site swelling 65 (2.7) 31 (2.6)
Irritability 450 (18.7) 237 (19.7)
Somnolence 303 (12.6) 171 (14.2)
Decreased  appetite 106 (4.4) 61 (5.1)
Solicited  Temperature  (Days 1 -5 postdose)
Temp  < 100.4  °F 2,319  (96.3) 1,154 (96.0)
Temp  ≥ 100.4  °F 89 (3.7) 48 (4.0)
AESI  (Days 1 -42 postdose)
Rashd 11 (0.5) 4 (0.3)
Anaphylaxis/hypersensitivity 1 (0.0)e 0 (0.0)•Proportion  of participants  with AEs, including  solicited  AEs, drug- 
related  AEs, and SAEs,  were  generally  comparable  between 
intervention  groups;  majority  of AEs were  Grade  1 or 2 toxicity
•Most  (≥ 96%)  participants  in either  intervention  group  had a 
maximum  temperature  <100.4 °F
•There  were  no serious  AESI  of rash,  anaphylaxis  or hypersensitivity 
observed  in either  intervention  group
•Proportion  of participants  with AESI  in the category  of rash 
(all non-serious)  was low in either  intervention  group
•One participante experienced  a non-serious  AESI  in the 
category  of anaphylaxis/hypersensitivity,  which  was a Grade 
2 event  of bronchospasm  on Day 3 postdose  in clesrovimab 
group,  not considered  related  to study  intervention  by 
investigator
•No deaths  were  considered  related  to study  intervention  by 
investigator;  no pattern  identified  with respect  to cause  of death 
or timing;  largely  attributable  to underlying  co-morbidities
Notes:  a. N = number  of participants randomized  and dosed  and included  in the safety  population;  b. One infant  had an SAE of body  temperature  increased  in the clesrovimab  group  (with  rectal  temperature  38°C 
on Day 4 and with adenovirus  detected  in stool  on Day 8) and one  infant  had an SAE of B-cell lymphoma  in the placebo  group;  c. One death  occurred  in the clesrovimab group  on Day 487 after study  discontinuation 
(discontinued  study  based  on physician’s  recommendation);  d. All AESI  of rash were  non-serious;  All events  were  Grade  1 or 2 toxicity  except  for one Grade  3 event  of urticaria  on Day 9 postdose  in clesrovimab  
group,  not considered  related  to study  intervention  by investigator.  Abbreviations : AE=Adverse  Event;  AESI=Adverse  Events  of Special  Interest;  SAE=Serious  Adverse  Event.
Confidential
Protocol  004:  Conclusions
12Efficacy
̶ Clesrovimab,  administered  as a single  
dose for infants  of all weights,  provides  
robust protection  against  mild,  
moderate,  and severe  RSV disease  for 
all healthy  infants, including  term and 
preterm
̶ Clinical  data demonstrate  over 90% efficacy 
in preventing  RSV LRI hospitalizations 
through  6 months
̶ Clesrovimab  efficacy  is durable  across  
all efficacy  endpoints  through  6 months
̶ There  was no shifting  of RSV  disease  
burden seen  in the second  RSV season
Safety
̶ Clesrovimab  is well tolerated  in healthy 
preterm  and full-term  infants  born during  or 
entering  their first RSV season, with a safety 
profile  that is generally  comparable  to placebo
Abbreviations:  LRI=Lower  Respiratory  Tract  Infection;  MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection;  RSV=Respiratory  Syncytial  Virus.
Protocol  007:
A Phase  3, Multicenter,  Randomized,  Partially  Blinded, 
Palivizumab - Controlled  Study  to Evaluate  the Safety,  Efficacy, 
and Pharmacokinetics  of Clesrovimab  in Infants  and Children  at 
Increased  Risk for Severe  RSV Disease
Confidential
Protocol  007: Study  Design
14•Safety  / Tolerability  – AEs up to day 42 and for 14 days after each 
subsequent  dose  and SAEs  for duration  of study  (primary)
•First  RSV Season  PK - Through  8 months
Palivizumab
3-5 doses  IM
(N = 450)
Clesrovimab
105 mg IM dose  [Day 1]
Placebo  [Day 28]
(N = 446)
Randomization 
1:1
(N = 896)aRSV-Associated  Efficacy
•MALRIb ≥ 1 Indicator  of 
LRI/Severity  (secondary)
•Hospitalization  (secondary)
•Severe  MALRI  (tertiary  / 
exploratory)
•MALRI  ≥ 2 Indicators  of 
LRI/Severity  (post -hoc)Experimental  Arm
Comparator  ArmFirst  RSV 
Season
Second 
RSV
Season(N = ~300)
Open -label
Clesrovimab
210 mg
To start  9 – 12 months  
following  participants’  
first RSV season  Dose  1
Notes:  a. N=Number  of randomized infants,  dosed  with clesrovimab  or palivizumab;  b. MALRI  is defined  as the presence  of the following in  a clinical  setting:  1) cough  or difficulty  breathing;  AND 2) 1 or more   
of wheezing,  chest  wall in-drawing/retraction,  rales/crackles,  hypoxemia,  tachypnea,  or dehydration;  AND 3) RSV-positive  reverse  transcriptase  polymerase  chain  reaction  (RT-PCR)  nasopharyngeal  sample; 
Abbreviations:  AE=Adverse  Event;  IM=Intramuscular;  MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection;  PK=Pharmacokinetics;  RSV=Respiratory  Syncytial  Virus;  SAE=Serious  Adverse  Event.Protocol  007 study  is 
ongoing  and data 
from  the second  RSV 
season  to be reported 
in the futureRSV-Associated  Efficacy
•MALRI  ≥ 1 Indicator  of 
LRI/Severity  (tertiary  / 
exploratory)
•Hospitalization  (tertiary  / 
exploratory)
•MALRI  ≥ 2 Indicators  of 
LRI/Severity  (post -hoc)At Month  5 At Month  6
Phase  3, multicenter,  randomized,  partially  blinded,  palivizumab -controlled  trial conducted  with active  surveillance over 2 RSV 
seasons
Objective:  Safety,  pharmacokinetics  and RSV-associated  endpoint  incidence  rates of clesrovimab  in infants  & 
children  at increased  risk for severe  RSV disease
Confidential
Protocol  007: Baseline  Characteristics
15Participant  Characteristics  `(`A`ll`D``o`sed Participants  – First RSV Season) Clesrovimab 
N = 446Palivizumab 
N = 450
Participants  in Population n (%) n (%)
Participants  with Condition
CLD 124 (27.8) 126 (28.0)
CHD 52 (11.7) 49 (10.9)
Neither  CLD nor CHD less than 29 weeks  gestational  agea 26 (5.8) 24 (5.3)
Neither  CLD nor CHD greater  than or  equal  to 29 weeks  gestational  agea 244 (54.7) 251 (55.8)
Age at Randomization  (Months)
<6 409 (91.7) 390 (86.2)
≥6 to <9 33 (7.4) 51 (11.3)
≥9 4 (0.9) 9 (2.0)
Mean  (SD) 3.0 (1.9) 3.0 (2.3)
Body  Weight  at Randomization  (kg)
Mean  (SD) 3.8 (1.5) 3.6 (1.5)
Median  (Range)3.5
(1.1 to 9.6)3.2
(1.5 to 9.1)
Race
American  Indian  Or Alaska  Native 5 (1.1) 7 (1.6)
Asian 82 (18.4) 80 (17.8)
Black  Or African  American 67 (15.0) 71 (15.8)
Multiple 56 (12.6) 53 (11.8)
Native  Hawaiian  Or Other  Pacific  Islander 5 (1.1) 2 (0.4)
White 231 (51.8) 237 (52.7)
Ethnicity
Hispanic  Or Latino 138 (30.9) 146 (32.4)
Not Hispanic  Or Latino 296 (66.4) 296 (65.8)
Not Reported  or Unknown 12 (2.7) 8 (1.8)
Sex
Male 225 (50.4) 221 (49.1)
Female 221 (49.6) 229 (50.9)
Notes:  a. Range  of gestational  age was 23 to 41 weeks;  Abbreviations : AAP=American  Academy  of Pediatrics;  CHD=Congenital  Heart  Disease;  CLD=Chronic  Lung Disease;  GA=Gestational  Age; RSV=Respiratory  Syncytial  Virus; 
SD=Standard  Deviation;  Source:  1. Pediatrics.  2014 Aug 1;134(2):e620-38.•Baseline  characteristics 
were  similar  in both 
clesrovimab and 
palivizumab  arms
•Enrolled  diverse population 
of different  races  and 
ethnicities  from  27
countries,  across  6 
continents
•In total,  401 of 896
(44.8%)  participants  met 
the American  Academy  of 
Pediatrics  (AAP) 
palivizumab  eligibility 
criteria  (101 CHD;  250 CLD;
50 <29 weeks  GA)1
Confidential
Protocol  007: Safety
Well-tolerated  in infants  at increased  risk of severe  RSV disease  with a safety  profile  that is generally  comparable  to 
palivizumab  
16Participants  with AEsClesrovimab 
Na = 445Palivizumab 
Na = 450
n (%) n (%)
Overall  Solicited and Unsolicited  AEs (following  any dose,  first RSV season)
≥ 1 AE 323 (72.6) 344 (76.4)
Drug -related  AE 120 (27.0) 127 (28.2)
Any SAE 99 (22.2) 110 (24.4)
Drug -related  SAE 0 (0.0) 2 (0.4)
Death 8 (1.8) 4 (0.9)
Solicited  AEs (days 1 -5 postdose,  first RSV season)
Injection  site pain 26 (5.8) 32 (7.1)
Injection  site erythema 29 (6.5) 20 (4.4)
Injection  site swelling 26 (5.8) 12 (2.7)
Irritability 116 (26.1) 125 (27.8)
Somnolence 74 (16.6) 72 (16.0)
Decreased  appetite 52 (11.7) 49 (10.9)
Solicited  Temperature  (days  1-5 postdose  1, first RSV season)
Temp  < 100.4  °F 436 (98.0) 441 (98.0)
Temp  ≥ 100.4  °F 9 (2.0) 9 (2.0)
AESI  (days 1 -42 postdose  1, first RSV season)
Rash 3 (0.7) 1 (0.2)
Anaphylaxis/hypersensitivity 0 (0.0) 0 (0.0)•Proportion  of participants  with AEs, including  solicited 
AEs, drug -related  AEs, and SAEs,  were  generally 
comparable  between  intervention  groups;  majority  of 
AEs were  Grade  1 or 2 toxicity
•Most  (≥ 98%)  participants  in either  intervention  group 
had a maximum  temperature  postdose  1 <100.4  °F
•No AESI  of anaphylaxis/hypersensitivity  were  reported, 
and the proportion  of participants  with AESI  of rash 
was low in either  intervention  group; all events  were 
non-serious  and Grade  1 toxicity
•No deaths  were  considered  related  to study 
intervention  by investigator;  no pattern  identified  with 
respect  to cause  of death  or timing;  largely  attributable 
to underlying  co-morbidities
Notes:  a. N = Number  of participants  randomized  and dosed  and included  in the safety  population;  Abbreviations: AE=Adverse  Event;  AESI=Adverse  Event  of Special  Interest;  SAE=Serious  Adverse  Event.
Confidential
Protocol  007: Incidence  Rates
Comparable  RSV disease  incidence  between  clesrovimab  and palivizumab  groups
17RSV-Associated  Endpointa
(Through  5 months  Postdose)Clesrovimab 
(N = 446)Palivizumab 
(N = 450)
nNumber  of 
EventsIncidence  Rate,  % 
(95% CI)d nNumber  of 
EventsIncidence  Rate,  % 
(95% CI)d
MALRI  Requiring  ≥ 1 
Indicator  of LRI/Severityb 443 143.6
(2.0, 6.0)437 123.0
(1.6, 5.3)
Hospitalizationc 443 51.3
(0.4,  3.0)437 61.5
(0.6,  3.3)
Notes : a. MALRI  includes  both inpatient  and outpatient  cases;  b. Defined  as: RSV PCR positive  and cough  or difficulty  breathing  and at least  1 of the following:  wheezing,  chest  wall indrawing/retractions,  
rales/crackles,  hypoxemia,  tachypnea,  or dehydration  due to respiratory  symptoms;  c. Respiratory  Infection  Hospitalization  defined  as: RSV PCR positive  and hospital  admission  for respiratory  illness;  d. 
Confidence  intervals  were  estimated  by exact  Poisson  confidence  limits;  N=number  of participants  randomized  and dosed  with clesrovimab  or palivizumab;  n=number  of participants eligible  for inclusion  in 
the full analysis  set population;  Abbreviations : CI=Confidence  Interval;  LRI=Lower  Respiratory  Tract  Infection;  MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection.Note:  Incidence  rates  in Protocol  007 are similar through  6 months  postdose
Confidential
Protocol  007: PK Bridging
Supports  extrapolation  of efficacy  to infants  with increased risk of severe RSV with no dose-adjustment  necessary
18•Non-inferiority  trial in infants  with increased risk of 
severe  RSV would  be infeasible  due to prohibitively 
large  sample  size in already  small  population
•In agreement  with regulators,  PK bridging  along 
with evaluation  of estimation  of efficacy  in Protocol 
007 was deemed  acceptable  for assessment  of 
efficacy  in this population
•PK exposures  in infants  with increased  risk for severe 
RSV are similar  to those  found  in healthy  infants , 
supporting  extrapolation  of efficacy  to population
of preterm  birth,  CLD and/or  CHD infants , without 
requiring  dose  adjustmentsReference  Group
Abbreviations : AUC=Area Under  the Curve;  CHD=Congenital  Heart Disease;  CLD=Chronic  Lung  Disease;  PK=Pharmacokinetics;  RSV=Respiratory  Syncytial  Virus.PK exposures  in infants  at increased  risk of severe  RSV 
are similar  to those  in healthy  infants
Confidential
Protocol  007: Conclusions
19Efficacy
̶ Efficacy  in Protocol  007 population  was 
inferred  by efficacy  established  from 
Protocol  004, based  on comparable 
clesrovimab  pharmacokinetic  data
̶ In infants  at increased  risk for severe  RSV 
disease,  a single  dose of clesrovimab 
protects  against  RSV disease , including  RSV 
hospitalization,  through  6 months
Safety
̶ The safety  profile of clesrovimab  in infants  at 
increased  risk of severe  RSV disease  is 
generally comparable  to palivizumab  and 
consistent  with the  safety  profile  in healthy  
infants
Abbreviations : RSV=Respiratory  Syncytial  Virus.
Summary
Confidential
Clesrovimab  Phase  2b/3 Study  Conclusions
21Efficacy
Clesrovimab,  administered  as a single  dose  for 
infants  of any weight,  provides  robust  protection 
against  mild,  moderate,  and severe  RSV disease 
for all infants,  including  term,  preterm,  and those 
with risk factors
✓In healthy  infants,  clesrovimab  is highly  efficacious 
against  a broad  spectrum  of RSV disease  endpoints, 
with no shifting  of RSV disease  burden  in second  RSV 
season  (Protocol  004)
✓Over  90% efficacy  in preventing  RSV LRI 
hospitalizations  through  6 months
✓Clesrovimab  also protects  infants  at increased  risk 
for severe  RSV disease , comparable  to palivizumab  
(Protocol  007)
✓The dose  is same  for infants  of all weights
✓Efficacy  is sustained  through  6 months,  providing  
durable  efficacy  for an entire  typical  RSV season
Safety
Clesrovimab  is well-tolerated  in infants,  with a 
safety  profile  that is generally  comparable  to 
controls  and consistent  across  infant 
populations.
̶ Clesrovimab  is well tolerated  in healthy  preterm 
and full-term  infants  born during  or entering  their 
first RSV  season, with a safety  profile  that is 
generally  comparable  to placebo
̶ The safety  profile  of clesrovimab  in infants  at 
increased  risk for severe  RSV disease  is generally 
comparable  to palivizumab  and consistent  with the 
safety  profile  in healthy  infants
Abbreviations : LRI=Lower  Respiratory  Tract  Infection;  MALRI=Medically -Attended  Lower  Respiratory  Tract  Infection;  RSV=Respiratory  Syncytial  Virus.
Thank  you