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Thorny Issues in HIV Vaccine Trials


Thorny Issues in HIV Vaccine Trials Saul Walker Policy Advisor IAVI – PowerPoint PPT presentation

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Title: Thorny Issues in HIV Vaccine Trials

Thorny Issues in HIV Vaccine Trials
  • Saul Walker
  • Policy Advisor
  • IAVI

Thorny Issues?
  • Vaccine positivity (including insurance)
  • Clades
  • Partial efficacy and end-points
  • Cohort selection
  • Phase 2b or not Phase 2b
  • Placebo selection
  • Standards of Care for trial participants in
    developing countries

Vaccine positivity
  • Vaccines often intended to induce antibodies
  • Standard HIV tests may show ve for vaccine
    induced response
  • Possible to determine true and vaccine positivity
    through selective tests, such as PCR
  • Volunteers provided with information and
    directions for future testing
  • Insurance
  • ABI recognised issue of vaccine positivity
  • Assumptions that volunteers are high risk

  • Genetic variability in HIV produced numerous

  • Genetic variability in HIV produced numerous
  • Variability challenging for vaccine design but
    dont know how important clade issue is
  • Animal data showing cross reactivity for a number
    of candidates
  • Only clinical data will be conclusive
  • Potential for multi-clade vaccines
  • VRC has an ABC product
  • Some parts of virus relatively well conserved
  • Broad protection a key objective

  • Types of Immunity
  • Sterilising Immunity (Vs) protection from
  • Disease mitigation (Vp) infection but delays or
    prevention of disease progression
  • Reduced Infectiveness (Vi) lower VL leading to
    reduced transmission
  • End points
  • For Vp focus has been on viral set point and/or
    time to treatment
  • Vi more difficult to design ethical trial
  • Limited Efficacy
  • Some of the people all of the time or all of the
    people some of the time
  • Efficacy and Effectiveness potential for
    behavioral reversals

Cohort Selection
  • Adolescents
  • A key group that could benefit from a vaccine
  • Consent issues and parental sensitivities
  • Discordant couples
  • Treatment for positive partner?
  • Possible European cohorts
  • Vulnerable groups
  • IDUs, sex workers, MSMs . Service men/women etc
  • Adding to existing stigma

Phase 2b Trials
  • Need to accelerate development and time to field
    while managing investment risks
  • Novel trial designs and strategies
  • Phase 2b - Proof of concept
  • Shorter trial designed to show efficacy gt 0
  • Expand into Phase 3 trial for license
  • Reduces initial trial costs but can increase
    total time
  • Reduces manufacturing investment risks
  • Designs that expand into Phase 3

Placebo Selection
  • Compare gold standard with gold standard
  • Under trial conditions, gold standard can
    dramatically reduce incidence
  • Availability of limited efficacy vaccines could
    make trials impractical
  • Phase 2b to Phase III transition?
  • Availability of new prevention options, such as

Standards of Care in Developing Countries
  • Trial participants package of care including
    primary care and HIV prevention
  • Treatment beyond trial not an ethical obligation
    for prevention trials
  • morally praiseworthy
  • Emerging consensus of how not if
  • Practical issues who, when, how long, ensuring
    provision, cost
  • Agreement on shared responsibilities
  • Sustainability
  • Trial/community disparities

Standards of Care in Developing Countries
  • Consultation essential
  • Policy development evolved in discussion with
    WHO-UNAIDS, other sponsors, researchers and NGOs
  • IAVI undertaken consultations in Uganda and India

IAVI SOC Policy - Commitments
  • Ongoing consultation on detail and implementation
  • Support primary healthcare and HIV prevention
    services to an agreed standard for trial
    participants for the duration of the trial
  • Support access to treatment, care and support,
    including ART when recommended by treatment
    guidelines, for participants who become HIV
    infected during a trial
  • Initial commitment of 5ys ART after start of
    treatment recommended
  • Funding for therapy through an Escrow Account or
    appropriate national scheme.
  • Treatment guidelines will be agreed with country
    stakeholders before trial initiation with WHO
    guidelines providing a baseline
  • IAVI will ensure referral to local support
    services for volunteers who are HIV-infected and
    who are screened out before enrolment

unless sufficiently covered under and existing
national programme
IAVI SOC Commitments
  • IAVI will work actively with country and
    international stakeholders to support
    opportunities for trial related investments to
    provide benefit to communities in which trials
    take place
  • Capacity building
  • Link trial activities with local HIV/AIDS
    programmes and health services
  • IAVI will work with country and international
    stakeholders to support
  • Sustained provision of treatment, care and
    support for trial participants who have become
    HIV infected during a trial
  • Opportunities to build on trial related
    investments to provide sustained community health