CLINICAL PHARMACOLOGY
Mechanism Of Action
Diphtheria
Diphtheria is an acute toxin-mediated disease caused by
toxigenic strains of C diphtheriae. Protection against disease is due to the
development of neutralizing antibodies to diphtheria toxin. A serum diphtheria
antitoxin level of 0.01 IU/mL is the lowest level giving some degree of
protection. Antitoxin levels of at least 0.1 IU/mL are generally regarded as
protective.13 Levels of 1.0 IU/mL have been associated with
long-term protection.14
Tetanus
Tetanus is an acute disease caused by an extremely potent
neurotoxin produced by C tetani. Protection against disease is due to the
development of neutralizing antibodies to tetanus toxin. A serum tetanus
antitoxin level of at least 0.01 IU/mL, measured by neutralization assay is
considered the minimum protective level.13,15 A tetanus antitoxoid
level ≥ 0.1 IU/mL as measured by the ELISA used in clinical studies of
Pentacel vaccine is considered protective.
Pertussis
Pertussis (whooping cough) is a respiratory disease
caused by B pertussis. This Gram-negative coccobacillus produces a
variety of biologically active components, though their role in either the
pathogenesis of, or immunity to, pertussis has not been clearly defined.
Poliomyelitis
Polioviruses, of which there are three serotypes (Types
1, 2, and 3) are enteroviruses. The presence of poliovirus type-specific
neutralizing antibodies has been correlated with protection against
poliomyelitis.16
Invasive Disease Due to H influenzae Type b
H influenzae type b can cause invasive disease
such as meningitis and sepsis. Anti-PRP antibody has been shown to correlate
with protection against invasive disease due to H influenzae type b. Based
on data from passive antibody studies17 and an efficacy study with H
influenzae type b polysaccharide vaccine in Finland,18 a
post-vaccination anti-PRP level of 0.15 mcg/mL has been accepted as a minimal
protective level. Data from an efficacy study with Hinfluenzae type b
polysaccharide vaccine in Finland indicate that a level > 1.0 mcg/mL 3 weeks
after vaccination predicts protection through a subsequent one-year period.19,20
These levels have been used to evaluate the effectiveness of Haemophilus b
Conjugate Vaccines, including the ActHIB vaccine component of Pentacel vaccine.
Clinical Studies
The efficacy of Pentacel vaccine is based on the
immunogenicity of the individual antigens compared to separately administered
vaccines. Serological correlates of protection exist for diphtheria, tetanus,
poliomyelitis, and invasive disease due to H influenzae type b. [See
CLINICAL PHARMACOLOGY] The efficacy against pertussis, for which there
is no well established serological correlate of protection, was based, in part,
on a comparison of pertussis immune responses following Pentacel vaccine in US
children to responses following DAPTACEL vaccine (Diphtheria and Tetanus
Toxoids and Acellular Pertussis Vaccine Adsorbed (DTaP) manufactured by Sanofi
Pasteur Limited) in an efficacy study conducted in Sweden (Sweden I Efficacy
Trial). While Pentacel and DAPTACEL vaccines contain the same pertussis
antigens, manufactured by the same process, Pentacel vaccine contains twice as
much detoxified PT and four times as much FHA as DAPTACEL vaccine.
Immune responses to Pentacel vaccine were evaluated in
four US studies: Studies 494-01, P3T06, 494-03, and M5A10. The vaccination
schedules of Pentacel vaccine, Control vaccines, and concomitantly administered
vaccines used in Studies 494-01, P3T06, and 494-03 are provided in Table 1.
[See ADVERSE REACTIONS).] In Study M5A10, participants were randomized to
receive Pentacel vaccine or separately administered DAPTACEL, IPOL, and ActHIB
vaccines at 2, 4, and months of age. 7-valent pneumococcal conjugate vaccine
(PCV7, Wyeth Pharmaceuticals Inc.) at 2, 4, and 6 months of age, and Hepatitis
B vaccine (Merck and Co. or GlaxoSmithKline Biologicals) at 2 and 6 months of
age, were administered concomitantly with Pentacel vaccine or Control vaccines.
Diphtheria
The proportions of participants achieving diphtheria
antitoxin seroprotective levels one month following three and four doses of
Pentacel vaccine or DAPTACEL vaccine in Study P3T06 are provided in Table 3.
Tetanus
The proportions of participants achieving tetanus
antitoxoid seroprotective levels one month following three and four doses of
Pentacel vaccine or DAPTACEL vaccine in Study P3T06 are provided in Table 3.
Table 3: Study P3T06 Diphtheria Antitoxin and Tetanus
Antitoxoid Responses One Month Following Dose 3 and Dose 4 of Pentacel Vaccine or
DAPTACEL + IPOL + ActHIB Vaccines in US Children Vaccinated at 2, 4, 6, and
15-16 Months of Age
Post-Dose 3 |
Pentacel Vaccine
N = 331-345 |
DAPTACEL + IPOL + ActHIB Vaccines
N = 1,037-1,099 |
Diphtheria Antitoxin |
% ≥ 0.01 IU/mL * |
100.00% |
100.00% |
% ≥ 0.10 IU/mL† |
98.80% |
98.50% |
Tetanus Antitoxoid |
% ≥ 0.10 IU/mL † |
99.70% |
100.00% |
Post-Dose 4 |
N = 341-352 |
N = 328-334 |
Diphtheria Antitoxin |
% ≥ 0.10 IU/mL* |
100.00% |
100.00% |
% ≥ 1.0 IU/mL† |
96.50% |
95.70% |
Tetanus Antitoxoid |
% ≥ 0.10 IU/mL* |
100.00% |
100.00% |
% ≥ 1.0 IU/mL †‡ |
92.90% |
99.40% |
Per Protocol Immunogenicity population.
* Seroprotection rate following Pentacel vaccine is not inferior to DAPTACEL
vaccine (upper limit of 90% CI of the difference DAPTACEL - Pentacel is
< 10%).
†Non-inferiority criteria were not pre-specified.
‡ With the ELISA used in this study, a tetanus antitoxoid level of 1.0 IU/mL is
10 times the protective level. |
Pertussis
In a clinical pertussis vaccine efficacy study conducted
in Sweden during 1992-1995 (Sweden I Efficacy Trial), 2,587 infants received
DAPTACEL vaccine and 2,574 infants received a non-US licensed DT vaccine as
placebo at 2, 4, and 6 months of age.1 The mean length of follow-up
was 2 years after the third dose of vaccine. The protective efficacy of
DAPTACEL vaccine against pertussis after 3 doses of vaccine using the World
Health Organization (WHO) case definition ( ≥ 21 consecutive days of
paroxysmal cough with culture or serologic confirmation or epidemiologic link
to a confirmed case) was 84.9% (95% confidence interval [CI] 80.1%, 88.6%). The
protective efficacy of DAPTACEL vaccine against mild pertussis ( ≥ 1 day of
cough with laboratory confirmation) was 77.9% (95% CI 72.6%, 82.2%). Protection
against pertussis by DAPTACEL vaccine was sustained for the 2-year follow-up
period.
Based on comparisons of the immune responses to DAPTACEL
vaccine in US infants (Post-Dose 3) and Canadian children (Post-Dose 4)
relative to infants who participated in the Sweden I Efficacy Trial, it was
concluded that 4 doses of DAPTACEL vaccine were needed for primary immunization
against pertussis in US children.1
In a serology bridging analysis, immune responses to FHA,
PRN and FIM in a subset of infants who received three doses of DAPTACEL vaccine
in the Sweden I Efficacy Trial were compared to the Post-Dose 3 and Post-Dose 4
responses in a subset of US children from Study 494-01 who received Pentacel
vaccine (Table 4). Available stored sera from infants who received DAPTACEL
vaccine in the Sweden I Efficacy Trial and sera from children who received PCV7
concomitantly with the first three doses of Pentacel vaccine in Study 494-01 (Table
1) were assayed in parallel. Data on levels of antibody to PT using an
adequately specific assay were not available for this serology bridging
analysis.
Geometric mean antibody concentrations (GMCs) and
seroconversion rates for antibodies to FHA, PRN and FIM one month following
Dose 3 of DAPTACEL vaccine in the subset of infants from the Sweden I Efficacy
Trial and one month following Dose 3 and Dose 4 of Pentacel vaccine in a subset
of infants from US Study 494-01 are presented in Table 4. Seroconversion was
defined as 4-fold rise in antibody level (Post-Dose 3/Pre-Dose 1 or Post-Dose
4/Pre-Dose 1). For anti- FHA and anti-FIM, the non-inferiority criteria were
met for seroconversion rates, and for anti-FHA, anti-PRN, and anti-FIM, the
non-inferiority criteria were met for GMCs, following Dose 4 of Pentacel vaccine
relative to Dose 3 of DAPTACEL vaccine. The non-inferiority criterion for
anti-PRN seroconversion following Dose 4 of Pentacel vaccine relative to Dose 3
of DAPTACEL vaccine was not met [upper limit of 95% CI for difference in rate
(DAPTACEL minus Pentacel) = 13.24%]. Whether the lower anti-PRN seroconversion
rate following Dose 4 of Pentacel vaccine in US children relative to Dose 3 of
DAPTACEL vaccine in Swedish infants correlates with diminished efficacy of
Pentacel vaccine against pertussis is unknown.
Table 4: FHA, PRN and FIM Antibody Responses One Month
Following Dose 3 of DAPTACEL Vaccine in a Subset of Infants Vaccinated at 2, 4,
and 6 Months of Age in the Sweden I Efficacy Trial and One Month Following Dose
3 and Dose 4 of Pentacel Vaccine in a Subset of Infants Vaccinated at 2, 4, 6,
and 15-16 Months of Age in US Study 494-01
|
Post-Dose 3 DAPTACEL Vaccine Sweden I Efficacy Trial
N = 80 |
Post-Dose 3 Pentacel Vaccine* US Study 494-01
N = 730-995 |
Post-Dose 4 Pentacel Vaccine † US Study 494-01
N = 507-554 |
Anti-FHA |
% achieving 4-fold rise‡ |
68.8 |
79.8 |
91.7§ |
GMC (EU/mL) |
40.70 |
71.46 |
129.85§ |
Anti-PRN |
% achieving 4-fold rise‡ |
98.8 |
74.4 |
89.2** |
GMC (EU/mL) |
111.26 |
38.11 |
90.82§ |
Anti-FIM |
% achieving 4-fold rise‡ |
86.3 |
86.5 |
91.5§ |
GMC (EU/mL) |
339.31 |
265.02 |
506.57§ |
Analyzed sera were from subsets of the Per Protocol
Immunogenicity populations in each study. Data on anti-PT levels using an
adequately specific assay were not available.
* Non-inferiority criteria were not pre-specified for the comparisons of immune
responses to Pentacel vaccine Post-Dose 3 vs. DAPTACEL vaccine Post-Dose 3.
† Â Pre-specified non-inferiority analyses compared immune responses to Pentacel
vaccine Post-Dose 4 vs. DAPTACEL vaccine Post-Dose 3.
‡ Fold rise was calculated as Post-Dose 3/Pre-Dose 1 antibody level or
Post-Dose 4/Pre-Dose 1 antibody level.
§ Percent achieving 4-fold rise or GMC Post-Dose 4 Pentacel vaccine is not
inferior to Post-Dose 3 DAPTACEL vaccine [upper limit of 95% CI for difference
in rates (DAPTACEL minus Pentacel) < 10% and upper limit of 90% CI for GMC
ratio (DAPTACEL/Pentacel) < 1.5].
** Non-inferiority criterion is not met for percent achieving 4-fold rise in
anti-PRN Post-Dose 4 Pentacel vaccine relative to Post-Dose 3 DAPTACEL vaccine
[upper limit of 95% CI for difference in rates (DAPTACEL minus Pentacel) =
13.24%, exceeds the non-inferiority criterion of < 10%]. |
In a separate study, Study P3T06, US infants were
randomized to receive either Pentacel vaccine or DAPTACEL + IPOL + ActHIB
vaccines at 2, 4, 6, and 15-16 months of age (Table 1). The pertussis immune
responses (GMCs and seroconversion rates) one month following the third and fourth
doses were compared between the two vaccine groups (Table 5). Seroconversion
was defined as a 4-fold rise in antibody level (Post-Dose 3/Pre-Dose 1 or
Post-Dose 4/Pre-Dose 1). Data on anti-PT responses obtained from an adequately
specific assay were available on only a non-random subset of study
participants. The subset of study participants was representative of all study
participants with regard to Pre-Dose 1, Post-Dose 3 and Post-Dose 4 GMCs of
antibodies to FHA, PRN and FIM. For each of the pertussis antigens,
non-inferiority criteria were met for seroconversion rates and GMCs following
Dose 3 of Pentacel vaccine relative to Dose 3 of DAPTACEL vaccine. Following
Dose 4 of Pentacel vaccine relative to Dose 4 of DAPTACEL vaccine,
non-inferiority criteria were met for all comparisons except for anti-PRN GMCs
[upper limit of 90% CI for ratio of GMCs (DAPTACEL/Pentacel) = 2.25]. Whether
the lower anti-PRN GMC following Dose 4 of Pentacel vaccine relative to Dose 4
of DAPTACEL vaccine in US children correlates with diminished efficacy of
Pentacel vaccine against pertussis is unknown.
Table 5: Pertussis Antibody Responses One Month
Following Doses 3 and 4 of Pentacel Vaccine or DAPTACEL + IPOL + ActHIB
Vaccines in US Infants Vaccinated at 2, 4, 6, and 15-16 Months of Age in Study
P3T06
|
Post-Dose 3 Pentacel Vaccine
N = 143 |
Post-Dose 3 DAPTACEL +IPOL + Act HIB Vaccines
N = 481-485 |
Post-Dose 4 Pentacel Vaccine
N = 113 |
Post-Dose 4 DAPTACEL + ActHIB Vaccines
N = 127-128 |
Anti-PT |
% achieving 4-fold rise* |
95.8† |
87.3 |
93.8‡ |
91.3 |
GMC (EU/mL) |
102.62† |
61.88 |
107.89‡ |
100.29 |
|
N = 218-318 |
N = 714-1,016 |
N = 230-367 |
N = 237-347 |
Anti-FHA |
% achieving 4-fold rise* |
81.9§ |
60.9 |
88.4** |
79.3 |
GMC (EU/mL) |
73.68§ |
29.22 |
107.94** |
64.02 |
Anti-PRN |
% achieving 4-fold rise* |
74.2§ |
75.4 |
92.7** |
98.3 |
GMC (EU/mL) |
36.05§ |
43.25 |
93.59†† |
186.07 |
Anti-FIM |
% achieving 4-fold rise* |
91.7§ |
86.3 |
93.5** |
91.6 |
GMC (EU/mL) |
268.15§ |
267.18 |
553.39** |
513.54 |
Per Protocol Immunogenicity population for anti-FHA,
anti-PRN, and anti-FIM. Non-random subset of per Protocol Immunogenicity
population for anti-PT. See text for further information on the subset
evaluated.
* Fold rise was calculated as Post-Dose 3/Pre-Dose 1 antibody level or
Post-Dose 4/Pre-Dose 1 antibody level.
† Percent achieving 4-fold rise or GMC Post-Dose 3 Pentacel vaccine not
inferior to Post-Dose 3 DAPTACEL vaccine [upper limit of 95% CI for GMC ratio
(DAPTACEL/Pentacel) < 1.5 and upper limit of 95% CI for differences in rates
(DAPTACEL minus Pentacel) < 10%].
‡ Percent achieving 4-fold rise or GMC Post-Dose 4 Pentacel vaccine not
inferior to Post-Dose 4 DAPTACEL vaccine [upper limit of 95% CI for GMC ratio
(DAPTACEL/Pentacel) < 1.5 and upper limit of 95% CI for differences in rates
(DAPTACEL minus Pentacel) < 10%].
§ Percent achieving 4-fold rise or GMC Post-Dose 3 Pentacel vaccine not inferior
to Post-Dose 3 DAPTACEL vaccine [upper limit of 90% CI for GMC ratio
(DAPTACEL/Pentacel) < 1.5 and upper limit of 90% CI for differences in rates
(DAPTACEL minus Pentacel) < 10%].
** Percent achieving 4-fold rise or GMC Post-Dose 4 Pentacel vaccine not
inferior to Post-Dose 4 DAPTACEL vaccine [upper limit of 90% CI for GMC ratio
(DAPTACEL/Pentacel) < 1.5 and upper limit of 90% CI for differences in rates
(DAPTACEL minus Pentacel) < 10%].
†† Non-inferiority criterion is not met for GMC Post-Dose 4 Pentacel vaccine
relative to Post-Dose 4 DAPTACEL vaccine [upper limit of 90% CI for GMC ratio
(DAPTACEL/Pentacel) = 2.25, which exceeds the non-inferiority criterion of
< 1.5]. |
Poliomyelitis
In Study P3T06 (Table 1), in which infants were randomized
to receive the first three doses of Pentacel vaccine or DAPTACEL + IPOL +
ActHIB vaccines at 2, 4, and 6 months of age, one month following the third
dose of study vaccines, ≥ 99.4% of participants in both groups (Pentacel:
N = 338-350), (DAPTACEL + IPOL + ActHIB: N = 1,050-1,097) achieved neutralizing
antibody levels of ≥ 1:8 for Poliovirus types 1, 2, and 3.
In Study 494-01 (Table 1), in which infants were
randomized to receive Pentacel vaccine or HCPDT + POLIOVAX + ActHIB vaccines,
GMTs (1/dil) of antibodies to Poliovirus types 1, 2, and 3 one month following
Dose 4 of Pentacel vaccine (N = 851-857) were 2,304, 4,178, and 4,415,
respectively, and one month following Dose 4 of POLIOVAX vaccine (N = 284-287)
were 2,330, 2,840, and 3,300, respectively.
Invasive Disease Due To H influenzae Type b
Anti-PRP seroprotection rates and GMCs one month
following Dose 3 of Pentacel vaccine or separately administered ActHIB vaccine
in studies 494-01, P3T06, and M5A10 are presented in Table 6. In Study 494-01,
non-inferiority criteria were not met for the proportion of participants who
achieved an anti-PRP level ≥ 1.0 mcg/mL and for anti-PRP GMCs following
Pentacel vaccine compared with separately administered ActHIB vaccine. In each
of Studies P3T06 and M5A10, the non-inferiority criterion was met for the
proportion of participants who achieved an anti-PRP level > 1.0 mcg/mL
following Pentacel vaccine compared with separately administered ActHIB
vaccine. In Study M5A10, the non-inferiority criterion was met for anti-PRP
GMCs following Pentacel vaccine compared with separately administered ActHIB
vaccine.
Table 6: Anti-PRP Seroprotection Rates and GMCs One
Month Following Three Doses of Pentacel Vaccine or Separate DTaP + IPV + ActHIB
Vaccines Administered at 2, 4, and 6 Months of Age in Studies 494-01, P3T06,
and M5A10
|
Study 494-01 |
Pentacel Vaccine
N = 1,127 |
HCPDT + POLIOVAX + ActHIB Vaccines
N = 401 |
% achieving anti-PRP ≥ 0.15 mcg/mL |
95.4* |
98.3 |
% achieving anti-PRP ≥ 1.0 mcg/mL |
79.1† |
88.8 |
Anti-PRP GMC (mcg/mL) |
3.19‡ |
6.23 |
|
Study P3T06 |
Pentacel Vaccine
N = 365 |
DAPTACEL + IPOL +ActHIB Vaccines
N = 1,128 |
% achieving anti-PRP ≥ 0.15 mcg/mL |
92.3* |
93.3 |
% achieving anti-PRP ≥ 1.0 mcg/mL |
72.1* |
70.8 |
Anti-PRP GMC (mcg/mL) |
2.31 § |
2.29 |
|
Study M5A10 |
Pentacel Vaccine
N = 826 |
DAPTACEL + IPOL +ActHIB Vaccines
N = 421 |
% achieving anti-PRP ≥ 0.15 mcg/mL |
93.8** |
90.3 |
% achieving anti-PRP ≥ 1.0 mcg/mL |
75.1** |
74.8 |
Anti-PRP GMC (mcg/mL) |
2.52†† |
2.38 |
Per Protocol Immunogenicity population for all studies.
IPV indicates Poliovirus Vaccine Inactivated.
*Percent achieving specified level following Pentacel vaccine not inferior to
ActHIB vaccine [upper limit of 90% CI for difference in rates (ActHIB minus
Pentacel) < 10%].
† Non-inferiority criterion not met for percent achieving anti-PRP ≥ 1.0
mcg/mL following Pentacel vaccine relative to ActHIB vaccine [upper limit of
90% CI for difference in rates (ActHIB minus Pentacel), 12.9%, exceeds the
non-inferiority criterion < 10%].
‡ Non-inferiority criterion not met for GMC following Pentacel vaccine relative
to ActHIB vaccine [upper limit of 90% CI of GMC ratio (ActHIB/Pentacel), 2.26,
exceeds the non-inferiority criterion < 1.5].
§ Non-inferiority criterion not pre-specified.
** Percent achieving specified level following Pentacel vaccine not inferior to
ActHIB vaccine [upper limit of 95% CI for difference in rates (ActHIB minus
Pentacel) < 10%].
†† GMC following Pentacel vaccine not inferior to ActHIB vaccine [upper limit
of 90% CI of GMC ratio (ActHIB/Pentacel) < 1.5]. |
In Study 494-01, at 15 months of age prior to receipt of
Dose 4 of study vaccines, 68.6% of Pentacel vaccine recipients (N = 829) and
80.8% of separately administered ActHIB vaccine recipients (N = 276) had an
anti-PRP level ≥ 0.15 mcg/mL. Following Dose 4 of study vaccines, 98.2% of
Pentacel vaccine recipients (N = 874) and 99.0% of separately administered
ActHIB vaccine recipients (N = 291) had an anti-PRP level ≥ 1.0 mcg/mL.
In Study P3T06, at 15 months of age prior to receipt of
Dose 4 of study vaccines, 65.4% of Pentacel vaccine recipients (N = 335) and
60.7% of separately administered ActHIB vaccine recipients (N = 323) had an
anti-PRP level ≥ 0.15 mcg/mL. Following Dose 4 of study vaccines, 97.8% of
Pentacel vaccine recipients (N = 361) and 95.9% of separately administered
ActHIB vaccine recipients (N = 340) had an anti-PRP level ≥ 1.0 mcg/mL.
Concomitantly Administered Vaccines
In Study P3T06, (Table 1) there was no evidence for
reduced antibody responses to hepatitis B vaccine (percent of participants with
anti-HBsAg ≥ 10 mlU/mL and GMCs) or PCV7 (percent of participants with
antibody levels ≥ 0.15 mcg/mL and ≥ 0.5 mcg/mL and GMCs to each
serotype) administered concomitantly with Pentacel vaccine (N = 321-325)
relative to these vaccines administered concomitantly with DAPTACEL + IPOL +
ActHIB vaccines (N = 998-1,029). The immune responses to hepatitis B vaccine
and PCV7 were evaluated one month following the third dose.
In Study 494-03, (Table 1) there was no evidence for
interference in the immune response to the fourth dose of PCV7 (percent of
participants with antibody levels ≥ 0.15 mcg/mL and ≥ 0.5 mcg/mL and
GMCs to each serotype) administered at 15 months of age concomitantly with
Pentacel vaccine (N = 155) relative to this vaccine administered concomitantly
with MMR and varicella vaccines (N = 158). There was no evidence for
interference in the immune response to MMR and varicella vaccines (percent of
participants with pre-specified seroresponse level) administered at 15 months
of age concomitantly with Pentacel vaccine (N = 154) relative to these vaccines
administered concomitantly with PCV7 (N = 144). The immune responses to MMR,
varicella vaccine and the fourth dose of PCV7 were evaluated one month
post-vaccination.
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