The PertADO Geneva Trial
Condition: Pertussis
MeSH terms: Whooping Cough
Study type: Interventional
Phase: Phase 2

Summary: 
      This is a phase II, randomized double-center, and observer-blind controlled pilot vaccine
      trial in 11 to 15 years old healthy subjects to assess the immunogenicity of the genetically
      detoxified pertussis toxin (rPT) included in a novel acellular pertussis vaccine (Pertagen®)
      manufactured by BioNet-Asia when delivered by the intramuscular route to adolescents
      previously primed and boosted with chemically-detoxified PT, along with Td-pur® and in
      comparison with that of Boostrix® dTpa.

      At Day 0, eligible volunteers will undergo a venous bleed for the determination of baseline
      values and enter the randomization scheme, being allocated to one of two groups: A (Pertagen®
      + Td-pur®), B (Boostrix® dTpa).

      Randomized participants will receive one dose of Pertagen® and Td-pur® (Group A) or 1 dose of
      Boostrix® dTpa (Group B) by intramuscular injection in the deltoid. All subjects will be
      observed in the Plateforme de Recherché Pédiatrique for 30 minutes after immunization.

      Post-immunization local and systemic reactions will be followed up for 7 days after
      immunization. Adverse events will be followed for 28 days after immunization.

      At Day 28, a second visit (study end visit) will take place for safety evaluation and blood
      draw for immunogenicity evaluation.

      Blood draws performed on Day 0 (Baseline) and Day 28 will be used to evaluate immune response
      to study vaccines.

      The primary statistical analysis will be performed with visit 2 (Day 28) data to compare the
      immunogenicity and safety of one dose of Pertagen®, given simultaneously with Td-pur®, to
      those elicited by Boostrix® dTpa.
    

Detailed description: 
      A significant increase of pertussis incidence is reported in a growing number of countries.
      This resurgence is considered as resulting from the limited durability of aP-vaccine-induced
      immunity and is associated with increased mortality in young infants and morbidity at all age
      groups. As the pertussis immunity acquired through immunization or infection is short-lived,
      its maintenance or reactivation requires repeat boosting at regular time points. Thus, novel
      strategies capable of reactivating pertussis immunity in older children, adolescents or
      adults, including pregnant women, are needed.

      A puzzling observation is that the efficacy of current acellular pertussis vaccines (which
      contain chemically-detoxified pertussis toxoid (PT)) is higher in infants and children than
      adolescents, in whom vaccine efficacy is limited and rapidly wanes. This may derive - at
      least in part - from priming and repeat immunizations with acellular vaccines containing
      chemically-detoxified PT and thus induction of antibodies specific of the
      chemically-detoxified PT but unable to efficiently recognize the native PT expressed by B.
      pertussis.

      The development of optimized acellular pertussis vaccines should thus include antigens with a
      similar immunogenicity profile as native PT but deprived of its toxic properties. This is
      best achieved through the genetic rather than chemical detoxification of PT, which results in
      both nontoxic and immunogenic PT.

      Clinical studies have shown the good tolerability profile and the superior immunogenicity
      profile of acellular pertussis vaccines including genetically-detoxified PT (rPT) in adults
      and adolescents previously primed with whole-cell pertussis (wP) vaccines. As whole-cell
      vaccines express native PT, whether the superior immunogenicity of rPT will be observed in
      adolescents/adults previously primed with acellular pertussis vaccines containing
      chemically-detoxified PT is of key importance.

      This is a phase II randomized, observer-blind controlled study to compare the safety and
      immunogenicity of acellular pertussis vaccines including chemically or genetically-detoxified
      pertussis toxin in adolescents aged 11-15 years. The primary objective is to assess the
      immunogenicity of the genetically detoxified pertussis toxin (rPT) included in a novel
      acellular pertussis vaccine (Pertagen®) when delivered by the intramuscular route to
      adolescents previously primed and boosted with chemically-detoxified PT, along with Td-pur®
      and in comparison with that of Boostrix® dTpa. The secondary objectives are (1) to assess
      safety of Pertagen® when administered with Td-pur® to adolescents as compared to Boostrix®
      dTpa and (2) to assess the humoral responses elicited by Pertagen® when administered with
      Td-pur® as compared to Boostrix® dTpa.

      In this study, exploratory immunological measures will also be performed (pending sufficient
      or additional funding). These are anticipated to include:

        -  The assessment of antibody titers to specific neutralizing and non-neutralizing epitopes
           of PT, by competitive ELISA, before and after (Day 28) boosting with Pertagen® and
           Boostrix® dTpa.

        -  To assess cellular responses to PT before and after boosting with Pertagen® and
           Boostrix® dTpa.

        -  To assess the frequency and phenotype of PT-specific memory B cell responses (as
           compared to tetanus toxoid) before and after boosting with Pertagen® or Boostrix® dTpa
           (i.e. at Day 0 and Day 28).

        -  To characterize changes in cellular responses following boosting with Pertagen® or
           Boostrix® dTpa

      Three vaccines will be used in the study. The BioNet-Asia study vaccine (Pertagen®), Td-pur®
      (Novartis/GSK) which will be concomitantly administered with the study vaccine, and the
      control Boostrix® dTpa.

      The investigational product Pertagen® will be manufactured, labeled, packaged and released
      for clinical use by BioNet-Asia, in accordance with the requirements of Good Manufacturing
      Practices.Both Td-pur® and Boostrix® dTpa vaccines used in this study are commercially
      available in Switzerland and will be purchased for the study. One batch of each vaccine will
      be used for the entire study.

      All vaccines are presented in 0.5 mL pre-filled syringes to be administered by intramuscular
      injection. The study vaccine Pertagen® and Boostrix® dTpa will be administered in the
      non-dominant deltoid. If applicable, Td-pur® will be administered in the contralateral
      deltoid.

      At Day 0, eligible subjects will be randomized in a 1:1 ratio into one of the following
      vaccine groups:

      Group 1 Pertagen® and Td-pur 30 volunteers Group 2 Boostrix® dTpa 30 volunteers

      A randomization list containing subject numbers and vaccine group assignments will be
      established and provided to the clinical investigators. Each participant will be immunized
      according to the vaccine group assignment. At study site, the Principal investigator will
      designate the blinded and unblinded teams in order to keep the observer-blind design of the
      study.

      The unblinded personal will be responsible for study vaccine preparation, handling, storage
      and accountability, and immunization.

      The blinded team will be responsible for assessing adverse events. The laboratory staff
      performing the immunological assays will also be blinded. After vaccination, volunteers will
      be observed for 30 minutes at study site for any immediate post-immunization reactions.
      Reactogenicity and safety will be assessed during study visits at the clinical trial unit
      (CTU) on Day 0 and Day 28 after immunization. At Day 0 (Visit 1, vaccination day), a Diary
      Card will be distributed to study volunteer to record post-immunization local and systemic
      reactions and adverse events. At Day 28 (Visit 2), investigator will reconcile and transcribe
      the Diary Card information in the CRF. Post-immunization local and systemic reactions will be
      collected and monitored for 7 days after vaccination. All adverse events, including SAEs,
      will be collected and monitored for 28 days after vaccination (until Visit 2).

      Study participants will be contacted by phone at Day 7 to confirm that adverse reactions have
      subsided. Should this not be the case, an unscheduled visit will be considered as
      appropriate.

      All AEs and SAEs occurring within the 28 days following treatment and observed by the
      Investigator or reported by the volunteer, whether or not attributed to study intervention,
      will be recorded in the CRF. All AEs that result in a volunteer's withdrawal from the study
      will be followed up until a satisfactory resolution occurs, or until a non-study related
      causality is assigned (if the volunteer consents to this).

      Sample size calculation This is a phase II randomized, observer-blind controlled pilot study
      to compare the safety and immunogenicity of acellular pertussis vaccines including chemically
      or genetically-detoxified pertussis toxin in adolescents previously immunized with acellular
      vaccines. The sample size for this study is based on clinical and practical considerations
      and not on a formal statistical power calculation. Where applicable, 2-sided test at the 5%
      significance level will be utilized with no multiplicity adjustment. P-values will be
      considered exploratory only. Sixty volunteers will be randomized in total, with 30 in each
      group.

      Safety analysis The safety analysis will include all randomized subjects who have received a
      dose of study vaccine.

      The overall percentage of subjects with at least one spontaneously reported adverse event,
      with date of onset up to 28 days after vaccination will be tabulated with exact 95%
      confidence intervals, by type of adverse event; by severity; and by causality. They will be
      displayed by vaccine group as both frequencies and percentages on the ITT data set.

      All reported adverse events that start post-vaccination will be tabulated. If a given disease
      is already reported as ongoing at the first visit on the medical history pages, it will be
      counted and tabulated as a vaccine emergent adverse event only if it worsens after the
      immunization with the study vaccine.

      Serious adverse events and discontinuation due to adverse event(s) will be described in
      detail by vaccine group.

      Immunogenicity analyses The primary immunogenicity endpoint will assess the immune response
      to Pertagen® - as compared to Boostrix® dTpa - by measuring the Day 28 geometric mean
      concentration (GMC) of neutralizing antibodies to PT.

      The other immunogenicity end-points include:

        -  GMCs of PT, FHA, tetanus and diphtheria-toxoid specific IgG antibodies measured by ELISA

        -  Seroresponse rates of PT, FHA, tetanus and diphtheria-toxoid specific IgG antibodies
           measured by ELISA

        -  Reverse cumulative distribution curves of PT neutralizing antibodies, and of PT, FHA,
           tetanus and diphtheria-toxoid IgG antibodies

        -  To compare PT-specific responses elicited by Pertagen® in adolescents previously
           immunized (this study) or not (BioNet Phase II/III TDA202) by acellular pertussis
           vaccines The following descriptive statistics will be provided for each variable: number
           of subjects, percentages, mean, geometric mean, standard deviation, median, minimum,
           maximum, and range.

      Quality Control and Quality Assurance Procedure Approved site-specific SOPs will be used at
      clinical and laboratory sites. Monitoring will be performed according to ICH Good Clinical
      Practice (GCP) by the Centre de Recherche Clinique (CRC) of the University Hospital of
      Geneva. Following a Monitoring Plan and written SOPs, the monitors will verify that the
      clinical trial is conducted and data are generated, documented and reported in compliance
      with the protocol, GCP and the applicable regulatory requirements. The CTU will provide
      direct access to all trial-related source data, documents and reports for the purpose of
      monitoring and inspection by local and regulatory authorities.
    

Intervention name(s): Pertagen® aP + Td-pur®; Boostrix® dTpa
Intervention type(s): Biological; Biological
Intervention description(s): see arm/group descriptions; see arm/group descriptions
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention
Keywords: Acellular pertussis vaccines Genetically-detoxified pertussis toxin Adolescents