CLINICAL PHARMACOLOGY
Mechanism Of Action
Tetanus
Tetanus is a condition manifested primarily by
neuromuscular dysfunction caused by a potent exotoxin released by C. tetani.
Protection against disease is due to the development of neutralizing antibodies
to the tetanus toxin. A serum tetanus antitoxin level of at least 0.01 IU/mL,
measured by neutralization assays, is considered the minimum protective level.2
A level ≥ 0.1 IU/mL by ELISA has been considered as protective.
Diphtheria
Diphtheria is an acute toxin-mediated infectious disease
caused by toxigenic strains of C. diphtheriae. Protection against
disease is due to the development of neutralizing antibodies to the diphtheria
toxin. A serum diphtheria antitoxin level of 0.01 IU/mL, measured by
neutralization assays, is the lowest level giving some degree of protection; a
level of 0.1 IU/mL by ELISA is regarded as protective.3 Diphtheria
antitoxin levels ≥ 1.0 IU/mL by ELISA have been associated with long-term
protection.3
Pertussis
Pertussis (whooping cough) is a disease of the
respiratory tract caused by B. pertussis. The role of the different
components produced by B. pertussis in either the pathogenesis of, or
the immunity to, pertussis is not well understood.
Clinical Studies
The efficacy of the tetanus and diphtheria toxoid
components of BOOSTRIX is based on the immunogenicity of the individual
antigens compared to US-licensed vaccines using established serologic
correlates of protection. The efficacy of the pertussis components of BOOSTRIX
was evaluated by comparison of the immune response of adolescents and adults following
a single dose of BOOSTRIX to the immune response of infants following a 3-dose primary
series of INFANRIX. In addition, the ability of BOOSTRIX to induce a booster response
to each of the antigens was evaluated.
Efficacy Of INFANRIX
The efficacy of a 3-dose primary series of INFANRIX in
infants has been assessed in 2 clinical studies: A prospective efficacy trial
conducted in Germany employing a household contact study design and a
double-blind, randomized, active Diphtheria and Tetanus Toxoids (DT)-controlled
trial conducted in Italy sponsored by the National Institutes of Health (NIH)
(for details see INFANRIX prescribing information). Serological data
from a subset of infants immunized with INFANRIX in the household contact study
were compared with the sera of adolescents and adults immunized with BOOSTRIX [see
Clinical Studies]. In the household contact study, the protective
efficacy of INFANRIX, in infants, against WHO-defined pertussis (21 days or
more of paroxysmal cough with infection confirmed by culture and/or serologic
testing) was calculated to be 89% (95% CI: 77%, 95%). When the definition of pertussis
was expanded to include clinically milder disease, with infection confirmed by
culture and/or serologic testing, the efficacy of INFANRIX against ≥ 7
days of any cough was 67% (95% CI: 52%, 78%) and against ≥ 7 days of
paroxysmal cough was 81% (95% CI: 68%, 89%) (for details see INFANRIX
prescribing information).
Immunological Evaluation In Adolescents
In a multicenter, randomized, controlled study conducted
in the United States, the immune responses to each of the antigens contained in
BOOSTRIX were evaluated in sera obtained approximately 1 month after
administration of a single dose of vaccine to adolescent subjects (10 to 18
years of age). Of the subjects enrolled in this study, approximately 76% were 10
to 14 years of age and 24% were 15 to 18 years of age. Approximately 98% of
participants in this study had received the recommended series of 4 or 5 doses
of either DTwP or a combination of DTwP and DTaP in childhood. The
racial/ethnic demographics were as follows: white 85.8%, black 5.7%, Hispanic
5.6%, Oriental 0.8%, and other 2.1%.
Response to Tetanus and Diphtheria Toxoids
The antibody responses to the tetanus and diphtheria
toxoids of BOOSTRIX compared with Td vaccine are shown in Table 6. One month
after a single dose, anti-tetanus and anti-diphtheria seroprotective rates ( ≥ 0.1
IU/mL by ELISA) and booster response rates were comparable between BOOSTRIX and
the comparator Td vaccine.
Table 6:Antibody Responses to Tetanus and Diphtheria
Toxoids Following BOOSTRIX Compared With Td Vaccine in Adolescents 10 to 18
Years of Age (ATP Cohort for Immunogenicity)
|
N |
% ≥ 0.1 IU/mLa (95% CI) |
% ≥ 1.0 IU/mLa (95% CI) |
% Booster Responseb (95% CI) |
Anti-Tetanus |
BOOSTRIX |
2,469 - 2,516 |
|
|
|
Pre-vaccination |
|
97.7 (97.1, 98.3) |
36.8 (34.9, 38.7) |
- |
Post-vaccination |
|
100 (99.8, 100)c |
99.5 (99.1, 99.7)d |
89.7 (88.4, 90.8)c |
Td |
817 - 834 |
|
|
|
Pre-vaccination |
|
96.8 (95.4, 97.9) |
39.9 (36.5, 43.4) |
- |
Post-vaccination |
|
100 (99.6, 100) |
99.8 (99.1, 100) |
92.5 (90.5, 94.2) |
Anti-Diphtheria |
BOOSTRIX |
|
|
|
|
Pre-vaccination |
2,463 - 2,515 |
85.8 (84.3, 87.1) |
17.1 (15.6, 18.6) |
- |
Post-vaccination |
|
99.9 (99.7, 100)c |
97.3 (96.6, 97.9)d |
90.6 (89.4, 91.7)c |
Td |
814 - 834 |
|
|
|
Pre-vaccination |
|
84.8 (82.1, 87.2) |
19.5 (16.9, 22.4) |
- |
Post-vaccination |
|
99.9 (99.3, 100) |
99.3 (98.4, 99.7) |
95.9 (94.4, 97.2) |
Td manufactured by MassBioLogics.
ATP = according-to-protocol; CI = Confidence Interval.
a Measured by ELISA.
b Booster response: In subjects with pre-vaccination < 0.1 IU/mL,
post-vaccination concentration ≥ 0.4 IU/mL. In subjects with
pre-vaccination concentration ≥ 0.1 IU/mL, an increase of at least 4 times
the pre-vaccination concentration.
c Seroprotection rate or booster response rate to BOOSTRIX was
non-inferior to Td (upper limit of two-sided 95% CI on the difference for Td
minus BOOSTRIX ≤ 10%).
d Non-inferiority criteria not prospectively defined for this
endpoint. |
Response to Pertussis Antigens
The booster response rates of adolescents to the pertussis
antigens are shown in Table 7. For each of the pertussis antigens the lower
limit of the two-sided 95% CI for the percentage of subjects with a booster
response exceeded the predefined lower limit of 80% for demonstration of an acceptable
booster response.
Table 7: Booster Responses to the Pertussis Antigens
Following BOOSTRIX in Adolescents 10 to 18 Years of Age (ATP Cohort for
Immunogenicity)
|
N |
BOOSTRIX % Booster Responsea (95% CI) |
Anti-PT |
2,677 |
84.5 (83.0, 85.9) |
Anti-FHA |
2,744 |
95.1 (94.2, 95.9) |
Anti-pertactin |
2,752 |
95.4 (94.5, 96.1) |
ATP = according-to-protocol; CI = Confidence Interval.
a Booster response: In initially seronegative subjects ( < 5
EL.U./mL), post-vaccination antibody concentrations ≥ 20 EL.U./mL. In
initially seropositive subjects with pre-vaccination antibody concentrations ≥ 5
EL.U./mL and < 20 EL.U./mL, an increase of at least 4 times the pre-vaccination
antibody concentration. In initially seropositive subjects with pre-vaccination
antibody concentrations ≥ 20 EL.U./mL, an increase of at least 2 times the
pre-vaccination antibody concentration. |
The GMCs to each of the pertussis antigens 1 month
following a single dose of BOOSTRIX in the US adolescent study (N =
2,941-2,979) were compared with the GMCs observed in infants following a 3-dose
primary series of INFANRIX administered at 3, 4, and 5 months of age (N =
631-2,884). Table 8 presents the results for the total immunogenicity cohort in
both studies (vaccinated subjects with serology data available for at least one
pertussis antigen; the majority of subjects in the study of INFANRIX had
anti-PT serology data only). These infants were a subset of those who formed
the cohort for the German household contact study in which the efficacy of
INFANRIX was demonstrated [see Clinical Studies]. Although a serologic
correlate of protection for pertussis has not been established, anti-PT, anti- FHA,
and anti-pertactin antibody concentrations observed in adolescents 1 month
after a single dose of BOOSTRIX were non-inferior to those observed in infants
following a primary vaccination series with INFANRIX.
Table 8: Ratio of GMCs to Pertussis Antigens Following
One Dose of BOOSTRIX in Adolescents 10 to 18 Years of Age Compared With 3 Doses
of INFANRIX in Infants (Total Immunogenicity Cohort)
|
GMC Ratio: BOOSTRIX/INFANRIX (95% CI) |
Anti-PT |
1.90 (1.82, 1.99)a |
Anti-FHA |
7.35 (6.85, 7.89)a |
Anti-pertactin |
4.19 (3.73, 4.71)a |
GMC = geometric mean antibody concentration, measured in
ELISA units; CI = Confidence Interval.
Number of subjects for BOOSTRIX GMC evaluation: Anti-PT = 2,941, anti-FHA =
2,979, and anti-pertactin = 2,978.
Number of subjects for INFANRIX GMC evaluation: Anti-PT = 2,884, anti-FHA =
685, and anti-pertactin = 631.
a GMC following BOOSTRIX was non-inferior to GMC following INFANRIX
(lower limit of 95% CI for the GMC ratio of BOOSTRIX/INFANRIX > 0.67). |
Immunological Evaluation In Adults (19 to 64 Years of Age)
A multicenter, randomized, observer-blinded study,
conducted in the United States, evaluated the immunogenicity of BOOSTRIX
compared with the licensed comparator Tdap vaccine (Sanofi Pasteur SA).
Vaccines were administered as a single dose to subjects (N = 2,284) who had not
received a tetanus-diphtheria booster within 5 years. The immune responses to
each of the antigens contained in BOOSTRIX were evaluated in sera obtained approximately
1 month after administration. Approximately 33% of patients were 19 to 29 years
of age, 33% were 30 to 49 years of age and 34% were 50 to 64 years of age.
Among subjects in the combined vaccine groups, 62% were female; 84% of subjects
were white, 8% black, 1% Asian, and 7% were of other racial/ethnic groups.
Response To Tetanus And Diphtheria Toxoids
The antibody responses to the tetanus and diphtheria
toxoids of BOOSTRIX compared with the comparator Tdap vaccine are shown in Table
9. One month after a single dose, anti-tetanus and anti-diphtheria
seroprotective rates ( ≥ 0.1 IU/mL by ELISA) were comparable between
BOOSTRIX and the comparator Tdap vaccine.
Table 9: Antibody Responses to Tetanus and Diphtheria
Toxoids Following One Dose of BOOSTRIX Compared With the Comparator Tdap
Vaccine in Adults 19 to 64 Years of Age (ATP Cohort for Immunogenicity)
|
N |
% ≥ 0.1 IU/mLa (95% CI) |
% ≥ 1.0 IU/mLa (95% CI) |
Anti-Tetanus |
BOOSTRIX |
1,445-1,447 |
|
|
Pre-vaccination |
|
95.9 (94.8, 96.9) |
71.9 (69.5, 74.2) |
Post-vaccination |
|
99.6 (99.1, 99.8)b |
98.3 (97.5, 98.9)b |
Tdap |
727-728 |
|
|
Pre-vaccination |
|
97.2 (95.8, 98.3) |
74.7 (71.4, 77.8) |
Post-vaccination |
|
100 (95.5, 100) |
99.3 (98.4, 99.8) |
Anti-Diphtheria |
BOOSTRIX |
1,440-1,444 |
|
|
Pre-vaccination |
|
85.2 (83.3, 87.0) |
23.7 (21.5, 26.0) |
Post-vaccination |
|
98.2 (97.4, 98.8)b |
87.9 (86.1, 89.5)c |
Tdap |
720-727 |
|
|
Pre-vaccination |
|
89.2 (86.7, 91.3) |
26.5 (23.3, 29.9) |
Post-vaccination |
|
98.6 (97.5, 99.3) |
92.0 (89.8, 93.9) |
Tdap = Tetanus Toxoid, Reduced Diphtheria Toxoid and
Acellular Pertussis Vaccine, Adsorbed manufactured by Sanofi Pasteur SA.
ATP = according-to-protocol; CI = Confidence Interval.
a Measured by ELISA.
b Seroprotection rates for BOOSTRIX were non-inferior to the
comparator Tdap vaccine (lower limit of 95% CI on the difference of BOOSTRIX
minus Tdap ≥ -10%).
c Non-inferiority criteria not prospectively defined for this
endpoint. |
Response to Pertussis Antigens
Booster response rates to the pertussis antigens are shown
in Table 10. For the FHA and pertactin antigens, the lower limit of the 95% CI
for the booster responses exceeded the pre-defined limit of 80% demonstrating
an acceptable booster response following BOOSTRIX. The PT antigen booster
response lower limit of the 95% CI (74.9%) did not exceed the pre-defined limit
of 80%.
Table 10: Booster Responses to the Pertussis Antigens
Following One Dose of BOOSTRIX in Adults 19 to 64 Years of Age (ATP Cohort for
Immunogenicity)
|
N |
BOOSTRIX % Booster Responsea (95% CI) |
Anti-PT |
1,419 |
77.2 (74.9, 79.3)b |
Anti-FHA |
1,433 |
96.9 (95.8, 97.7)c |
Anti-pertactin |
1,441 |
93.2 (91.8, 94.4)c |
ATP = according-to-protocol; CI = Confidence Interval.
a Booster response: In initially seronegative subjects ( < 5
EL.U./mL), post-vaccination antibody concentrations ≥ 20 EL.U./mL. In
initially seropositive subjects with pre-vaccination antibody concentrations ≥ 5
EL.U./mL and < 20 EL.U./mL, an increase of at least 4 times the
prevaccination antibody concentration. In initially seropositive subjects with
pre-vaccination antibody concentrations ≥ 20 EL.U./mL, an increase of at
least 2 times the pre-vaccination antibody concentration.
b The PT antigen booster response lower limit of the 95% CI did not
exceed the pre-defined limit of 80%.
c The FHA and pertactin antigens booster response lower limit of the
95% CI exceeded the predefined limit of 80%. |
The GMCs to each of the pertussis antigens 1 month
following a single dose of BOOSTRIX in the US adult (19 to 64 years of age)
study were compared with the GMCs observed in infants following a 3-dose
primary series of INFANRIX administered at 3, 4, and 5 months of age. Table 11
presents the results for the total immunogenicity cohort in both studies (vaccinated
subjects with serology data available for at least one pertussis antigen).
These infants were a subset of those who formed the cohort for the German
household contact study in which the efficacy of INFANRIX was demonstrated [see
Clinical Studies]. Although a serologic correlate of protection for
pertussis has not been established, anti-PT, anti-FHA, and antipertactin antibody
concentrations observed in adults 1 month after a single dose of BOOSTRIX were
non-inferior to those observed in infants following a primary vaccination
series with INFANRIX.
Table 11: Ratio of GMCs to Pertussis Antigens
Following One Dose of BOOSTRIX in Adults 19 to 64 Years of Age Compared With 3
Doses of INFANRIX in Infants (Total Immunogenicity Cohort)
|
GMC Ratio: BOOSTRIX/INFANRIX (95% CI) |
Anti-PT |
1.39 (1.32, 1.47)a |
Anti-FHA |
7.46 (6.86, 8.12)a |
Anti-pertactin |
3.56 (3.10, 4.08)a |
GMC = geometric mean antibody concentration; CI =
Confidence Interval.
Number of subjects for BOOSTRIX GMC evaluation: Anti-PT = 1,460, anti-FHA =
1,472, and anti-pertactin = 1,473.
Number of subjects for INFANRIX GMC evaluation: Anti-PT = 2,884, anti-FHA =
685, and anti-pertactin = 631.
a BOOSTRIX was non-inferior to INFANRIX (lower limit of 95% CI for
the GMC ratio of BOOSTRIX/INFANRIX > 0.67). |
Immunological Evaluation In The Elderly (65 Years of Age
and Older)
The US elderly (65 years of age and older) study, a
randomized, observer-blinded study, evaluated the immunogenicity of BOOSTRIX (N
= 887) compared with a US-licensed comparator Td vaccine (N = 445) (Sanofi
Pasteur SA). Vaccines were administered as a single dose to subjects who had
not received a tetanus-diphtheria booster within 5 years. Among all vaccine
recipients, the mean age was approximately 72 years of age; 54% were female and
95% were white. The immune responses to each of the antigens contained in
BOOSTRIX were evaluated in sera obtained approximately 1 month after
administration.
Response to Tetanus and Diphtheria Toxoids and Pertussis
Antigens
 Immune responses to tetanus and diphtheria toxoids and
pertussis antigens were measured 1 month after administration of a single dose
of BOOSTRIX or a comparator Td vaccine. Anti-tetanus and anti-diphtheria
seroprotective rates ( > 0.1 IU/mL) were comparable between BOOSTRIX and the comparator
Td vaccine (Table 12).
Table 12: Immune Responses to Tetanus and Diphtheria
Toxoids Following BOOSTRIX or Comparator Td Vaccine in the Elderly 65 Years of
Age and Older (ATP Cohort for Immunogenicity)
|
BOOSTRIX
(N = 844-864) |
Td
(N = 430-439) |
Anti-T |
% ≥ 0.1 IU/mL (95% CI) |
96.8 (95.4, 97.8)a |
97.5 (95.6, 98.7) |
% ≥ 1.0 IU/mL (95% CI) |
88.8 (86.5, 90.8)a |
90.0 (86.8, 92.6) |
Anti-D |
% ≥ 0.1 IU/mL (95% CI) |
84.9 (82.3, 87.2)a |
86.6 (83.0, 89.6) |
% ≥ 1.0 IU/mL (95% CI) |
52.0 (48.6, 55.4)b |
51.2 (46.3, 56.0) |
Td = Tetanus and Diphtheria Toxoids Adsorbed, a
US-licensed Td vaccine, manufactured by Sanofi Pasteur SA.
ATP = according-to-protocol; CI = Confidence Interval.
a Seroprotection rates for BOOSTRIX were non-inferior to the
comparator Td vaccine (lower limit of 95% CI on the difference of BOOSTRIX
minus Td ≥ -10%).
b Non-inferiority criteria not prospectively defined for this
endpoint. |
The GMCs to each of the pertussis antigens 1 month
following a single dose of BOOSTRIX were compared with the GMCs of infants
following a 3-dose primary series of INFANRIX administered at 3, 4, and 5
months of age. Table 13 presents the results for the total immunogenicity
cohort in both studies (vaccinated subjects with serology data available for at
least one pertussis antigen). These infants were a subset of those who formed
the cohort for the German household contact study in which the efficacy of
INFANRIX was demonstrated [see Clinical Studies]. Although a serologic
correlate of protection for pertussis has not been established, anti-PT,
anti-FHA, and anti-pertactin antibody concentrations in the elderly (65 years
of age and older) 1 month after a single dose of BOOSTRIX were non-inferior to
those of infants following a primary vaccination series with INFANRIX.
Table 13: Ratio of GMCs to Pertussis Antigens
Following One Dose of BOOSTRIX in the Elderly 65 Years of Age and Older
Compared With 3 Doses of INFANRIX in Infants (Total Immunogenicity Cohort)
|
GMC Ratio: BOOSTRIX/INFANRIX (95% CI) |
Anti-PT |
1.07 (1.00, 1.15)a |
Anti-FHA |
8.24 (7.45, 9.12)a |
Anti-pertactin |
0.93 (0.79, 1.10)a |
GMC = geometric mean antibody concentration; CI =
Confidence Interval.
Number of subjects for BOOSTRIX GMC evaluation: Anti-PT = 865, anti-FHA = 847,
and antipertactin= 878.
Number of subjects for INFANRIX GMC evaluation: Anti-PT = 2,884, anti-FHA =
685, and anti-pertactin = 631.
a BOOSTRIX was non-inferior to INFANRIX (lower limit of 95% CI for
the GMC ratio of BOOSTRIX/INFANRIX ≥ 0.67). |
Concomitant Vaccine Administration
Concomitant Administration With Meningococcal Conjugate
Vaccine
The concomitant use of BOOSTRIX and a tetravalent meningococcal
(groups A, C, Y, and W-135) conjugate vaccine (Sanofi Pasteur SA) was evaluated
in a randomized study in healthy adolescents 11 to 18 years of age. A total of
1,341 adolescents were vaccinated with BOOSTRIX. Of these, 446 subjects
received BOOSTRIX administered concomitantly with meningococcal conjugate
vaccine at different injection sites, 446 subjects received BOOSTRIX followed
by meningococcal conjugate vaccine 1 month later, and 449 subjects received meningococcal
conjugate vaccine followed by BOOSTRIX 1 month later.
Immune responses to diphtheria and tetanus toxoids (% of
subjects with anti-tetanus and anti-diphtheria antibodies ≥ 1.0 IU/mL by
ELISA), pertussis antigens (booster responses and GMCs), and meningococcal
antigens (vaccine responses) were measured 1 month (range 30 to 48 days) after
concomitant or separate administration of BOOSTRIX and meningococcal conjugate
vaccine. For BOOSTRIX given concomitantly with meningococcal conjugate vaccine compared
to BOOSTRIX administered first, non-inferiority was demonstrated for all
antigens, with the exception of the anti-pertactin GMC. The lower limit of the
95% CI for the GMC ratio was 0.54 for anti-pertactin (pre-specified limit ≥ 0.67).
For the anti-pertactin booster response, non-inferiority was demonstrated. It
is not known if the efficacy of BOOSTRIX is affected by the reduced response to
pertactin.
There was no evidence that BOOSTRIX interfered with the antibody
responses to the meningococcal antigens when measured by serum bactericidal
assays (rSBA) when given concomitantly or sequentially (meningococcal conjugate
vaccine followed by BOOSTRIX or BOOSTRIX followed by meningococcal conjugate
vaccine.
Concomitant Administration With FLUARIX (Influenza Virus
Vaccine)
The concomitant use of BOOSTRIX and FLUARIX was evaluated
in a multicenter, open-label, randomized, controlled study of 1,497 adults 19
to 64 years of age. In one group, subjects received BOOSTRIX and FLUARIX
concurrently (n = 748). The other group received FLUARIX at the first visit,
then 1 month later received BOOSTRIX (n = 749). Sera was obtained prior to and
1 month following concomitant or separate administration of BOOSTRIX and/or
FLUARIX, as well as 1 month after the separate administration of FLUARIX.
Immune responses following concurrent administration of
BOOSTRIX and FLUARIX were non-inferior to separate administration for
diphtheria (seroprotection defined as ≥ 0.1 IU/mL), tetanus (seroprotection
defined as ≥ 0.1 IU/mL and based on concentrations ≥ 1.0 IU/mL),
pertussis toxin (PT) antigen (anti-PT GMC) and influenza antigens (percent of subjects
with hemagglutination-inhibition [HI] antibody titer ≥ 1:40 and ≥ 4-fold
rise in HI titer). Non-inferiority criteria were not met for the anti-pertussis
antigens FHA and pertactin. The lower limit of the 95% CI of the GMC ratio was
0.64 for anti-FHA and 0.60 for anti-pertactin and the pre-specified limit was ≥ 0.67.
It is not known if the efficacy of BOOSTRIX is affected by the reduced response
to FHA and pertactin.
REFERENCES
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WA. Tetanus Toxoid. In: Plotkin SA, Orenstein WA, and Offit PA, eds. Vaccines. 5th
ed. Saunders; 2008:805-839.
3. Vitek CR and Wharton M. Diphtheria Toxoid. In: Plotkin
SA, Orenstein WA, and Offit PA, eds. Vaccines. 5th ed. Saunders; 2008:139-156.