Clinical Pharmacology for Pentacel
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. (12) Levels of 1.0 IU/mL have been associated with long-term protection. (13)
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. (12) (14) A tetanus antitoxoid level ≥0.1 IU/mL as measured by the ELISA used in clinical studies of Pentacel 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. (15)
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 studies (16) and an efficacy study with H. influenzae type b polysaccharide vaccine in Finland, (17) 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 H. influenzae 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. (18) (19) These levels have been used to evaluate the effectiveness of Haemophilus b Conjugate Vaccines, including the ActHIB component of Pentacel.
Clinical Studies
The efficacy of Pentacel is based on the immunogenicity of the individual antigens compared to separately administered vaccines. The poliovirus component (poliovirus types 1, 2 and 3) of this formulation of Pentacel is grown in Vero cells [see DESCRIPTION]. The clinical study data in this section were accrued with a Pentacel formulation in which the poliovirus component was grown in MRC-5 cells. The poliovirus component of the two Pentacel formulations are analytically comparable. 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 in US children to responses following DAPTACEL (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 contain the same pertussis antigens, manufactured by the same process, Pentacel contains twice as much detoxified PT and four times as much FHA as DAPTACEL. Immune responses to Pentacel were evaluated in four US studies: Studies 494-01, P3T06, 494-03, and M5A10. The vaccination schedules of Pentacel, Control vaccines, and concomitantly administered vaccines used in Studies 494-01, P3T06, and 494-03 are provided in Table 1 [see Clinical Trials Experience]. In Study M5A10, participants were randomized to receive Pentacel or separately administered DAPTACEL, IPOL, and ActHIB at 2, 4, and 6 months of age. 7-valent pneumococcal conjugate (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 or Control vaccines. (20)
Diphtheria
The proportions of participants achieving diphtheria antitoxin seroprotective levels one month following three and four doses of Pentacel or DAPTACEL 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 or DAPTACEL 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 or DAPTACEL + IPOL + ActHIB in US Children Vaccinated at 2, 4, 6, and 15-16 Months of Age
| Post-Dose 3 |
Pentacel
N = 331-345 |
DAPTACEL + IPOL+ ActHIB
N = 1,037-1,099 |
| Diphtheria Antitoxin % ≥0.01 IU/mL† |
100.0% |
100.0% |
| Diphtheria Antitoxin %≥0.10 IU/mL† |
98.8% |
98.5% |
| Tetanus Antitoxoid % ≥0.10 IU/mL† |
99.7% |
100.0% |
| Post-Dose 4 |
N = 341-352 |
N = 328-334 |
| Diphtheria Antitoxin % ≥0.10 IU/mL* |
100.0% |
100.0% |
| Diphtheria Antitoxin % ≥1.0 IU/mL† |
96.5% |
95.7% |
| Tetanus Antitoxoid % ≥0.10 IU/mL* |
100.0% |
100.0% |
| Tetanus Antitoxoid % ≥1.0 IU/mL†‡ |
92.9% |
99.4% |
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 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 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 against mild pertussis (≥1 day of cough with laboratory confirmation) was 77.9% (95% CI 72.6%, 82.2%). Protection against pertussis by DAPTACEL was sustained for the 2-year follow-up period.
Based on comparisons of the immune responses to DAPTACEL 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 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 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 (Table 4). Available stored sera from infants who received DAPTACEL in the Sweden I Efficacy Trial and sera from children who received PCV7 concomitantly with the first three doses of Pentacel 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 in the subset of infants from the Sweden I Efficacy Trial and one month following Dose 3 and Dose 4 of Pentacel 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 relative to Dose 3 of DAPTACEL. The non-inferiority criterion for anti-PRN seroconversion following Dose 4 of Pentacel relative to Dose 3 of DAPTACEL 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 in US children relative to Dose 3 of DAPTACEL in Swedish infants correlates with diminished efficacy of Pentacel against pertussis is unknown.
Table 4: FHA, PRN and FIM Antibody Responses One Month Following Dose 3 of DAPTACEL 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 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 Sweden I Efficacy Trial
N = 80 |
Post-Dose 3 Pentacel* US Study 494-01
N = 730-995 |
Post-Dose 4 Pentacelt 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.
†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 or DAPTACEL + IPOL + ActHIB 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 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 relative to Dose 3 of DAPTACEL. Following Dose 4 of Pentacel relative to Dose 4 of DAPTACEL, 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 relative to Dose 4 of DAPTACEL in US children correlates with diminished efficacy of Pentacel against pertussis is unknown.
Table 5: Pertussis Antibody Responses One Month Following Doses 3 and 4 of Pentacel or DAPTACEL + IPOL + ActHIB in US Infants Vaccinated at 2, 4, 6, and 15-16 Months of Age in Study P3T06
|
Post-Dose 3 Pentacel
N = 143 |
Post-Dose 3 DAPTACEL + IPOL + ActHIB
N = 481-485 |
Post-Dose 4 Pentacel
N = 113 |
Post-Dose 4 DAPTACEL + ActHIB
N = 127-128 |
| Anti-PT % achieving 4-fold rise* |
95.8† |
87.3 |
93.8‡ |
91.3 |
| Anti-PT GMC (EU/mL) |
102.62† |
61.88 |
107.89‡ |
100.29 |
|
Post-Dose 3 Pentacel N = 218-318 |
Post-Dose 3 DAPTACEL + IPOL + ActHIB N = 714-1,016 |
Post-Dose 4 Pentacel N = 230-367 |
Post-Dose 4 DAPTACEL + ActHIB N = 237-347 |
| Anti-FHA % achieving 4-fold rise* |
81.9§ |
60.9 |
88.4¶ |
79.3 |
| Anti-FHA 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 |
| Anti-PRN 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 |
| Anti-FIM 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]. |
Study 006 was a study conducted in the US, where infants were randomized to receive 3 doses of VAXELIS at 2, 4, and 6 months of age and Pentacel at 15 months of age (N = 2,406), or control group vaccines (4 doses of Pentacel at 2, 4, 6, and 15 months of age + RECOMBIVAX HB [Hepatitis B Vaccine (Recombinant)] at 2 and 6 months of age; N = 402). All subjects received concomitant Prevnar 13 (Pneumococcal 13-valent Conjugate Vaccine [Diphtheria CRM197 Protein]) at 2, 4, 6, and 15 months of age.
Participants were evaluated for immune responses to pertussis antigens one month following the dose of Pentacel administered at 15 months of age. The non-inferiority criteria for antibody vaccine response rates and GMCs for all pertussis antigens were met following the fourth dose except for GMCs for PRN (lower bound of 2-sided 95% CI for GMC ratio [VAXELIS group/Control group vaccines] was 0.66, which was below the non-inferiority criterion >0.67). (20)
Poliomyelitis
In Study P3T06 (Table 1), in which infants were randomized to receive the first three doses of Pentacel or DAPTACEL + IPOL + ActHIB 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 or HCPDT + POLIOVAX + ActHIB, GMTs (1/dil) of antibodies to Poliovirus types 1, 2, and 3 one month following Dose 4 of Pentacel (N = 851-857) were 2,304, 4,178, and 4,415, respectively, and one month following Dose 4 of POLIOVAX (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 or separately administered ActHIB 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 compared with separately administered ActHIB. 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 compared with separately administered ActHIB. In Study M5A10, the non-inferiority criterion was met for anti-PRP GMCs following Pentacel compared with separately administered ActHIB.
Table 6: Anti-PRP Seroprotection Rates and GMCs One Month Following Three Doses of Pentacel or Separate DTaP + IPV + ActHIB Administered at 2, 4, and 6 Months of Age in Studies 494-01, P3T06, and M5A10
|
Study 494-01 Pentacel
N = 1,127 |
Study 494-01 HCPDT + POLIOVAX + ActHIB
N = 401 |
| % achieving anti-PRP ≥0.15 mcg/mL |
92.3* |
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
N = 365 |
Study P3T06 DAPTACEL + IPOL + ActHIB
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
N = 826 |
Study M5A10 DAPTACEL + IPOL + ActHIB
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 recipients (N = 829) and 80.8% of separately administered ActHIB recipients (N = 276) had an anti-PRP level ≥0.15 mcg/mL. Following Dose 4 of study vaccines, 98.2% of Pentacel recipients (N = 874) and 99.0% of separately administered ActHIB 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 recipients (N = 335) and 60.7% of separately administered ActHIB recipients (N = 323) had an anti-PRP level ≥0.15 mcg/mL. Following Dose 4 of study vaccines, 97.8% of Pentacel recipients (N = 361) and 95.9% of separately administered ActHIB 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 mIU/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 (N = 321-325) relative to these vaccines administered concomitantly with DAPTACEL + IPOL + ActHIB (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 (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 (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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