Biomedical HIV Prevention Research

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Biomedical HIV Prevention Research
Where are we? And where do we go from
here? Mitchell Warren Executive Director,
AVAC National Press Foundation _at_ IAS/Cape
Town 17 July 2009
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HIV/AIDS Toolkit
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A comprehensive, integrated sustained response
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What is PrEP?

• Experimental HIV prevention strategy that would
  use antiretrovirals (ARVs) to protect
  HIV-negative people from HIV infection
• In this strategy, people would take a single
  drug, or a combination of drugs, before exposure
  to HIV, with the hope that it would lower their
  risk of infection
• Possibility of daily dosing and intermittent
  dosing being tested
• PrEP is not yet proven to work

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Why the interest in PrEP?

• Data from numerous animal challenge models show
  protection from PrEP
• ARVs for PMTCT provides proof of concept in
  humans
• Success of Post-Exposure Prophylaxis (PEP) for
  needlestick exposure in observational data
• PrEP builds on the concept that medications can
  be used by healthy people to prevent some
  infections
• Malaria prophylaxis for travelers
• Assumption that stopping HIV replication as soon
  as virus enters the body may prevent permanent
  infection

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Ideal PrEP Product Criteria

• Safety profile use for years in healthy
  individuals
• Ease of use once daily, weekly, intermittent,
  missed dose
• Good drug penetration at the viral portals of
  entry (rectum and genital tract)
• High effectiveness in real world situations
• High barrier for resistance requirement for
  multiple mutations to cause virologic failure
• Limited impact on therapy low or no level of
  cross resistance)
• Cost effective and accessible

Derdelinckx et al PLosMedicine 2006
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Current PrEP Products Being Studies

• Current oral PrEP trials are testing tenofovir
  disoproxil fumarate (TDF) and a combination of
  TDF plus emtricitabine (FTC)
• TDF is marketed under the name Viread, and
  TDF/FTC is marketed under the name Truvada, both
  made by Gilead Sciences, Inc.
• Also current trials of tenofovir gel as a topical
  microbicide

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Why TDF and TDF/FTC?

• Limited side effects
• Strong safety profile as therapy among HIV
  positive people
• Relatively long duration of action in the body
  (product half-life)
• Less likelihood of promoting drug resistance
  compared to other ARVs

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Current PrEP Studies

• Seven current studies of daily oral PrEP small
  intermittent study to start in July 2009
• Almost 20,000 participants currently or soon to
  be enrolled
• Designed to produce results in diverse
  populations, representing multiple routes of
  transmission
• Men and women in high prevalence locations
• Sero-discordant heterosexual couples
• Injection drug users
• Gay men other men who have sex with men (MSM)

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2008 Investments in PrEP RD
From Adapting to Realities Trends in HIV
Prevention Research Funding, 2000 to 2008, HIV
Vaccines and Microbicides Resource Tracking
Working Group, July 2008
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What questions will remain after the current
trials?

• Additional populations not in current trials,
  e.g. adolescents and pregnant women
• Intermittent dosing schedules
• Other possible drugs for PrEP
• Potential resistance if infection does occur
  while on PrEP

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Current (and Future) PrEP Challenges

• Is it safe to give ARV drugs to uninfected
  people?
• Will those who get infected while taking PrEP
  have HIV that is resistant to the PrEP
  antiretrovirals? Will this affect subsequent care
  and choice of ARV treatment?
• Will people adhere to daily PrEP for long
  periods?
• Is intermittent PrEP more acceptable, and is it
  safe and effective?
• How often to do HIV testing on people on PrEP?
• Is there behavioral disinhibition/risk
  compensation?
• Is this an affordable and practical HIV
  prevention strategy for scale-up?

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What Is Needed Now?

• Ensure the current clinical trials have the best
  chance of producing decisive results.
• Identify and invest in additional research.
• Plan now for optimal use of PrEP.
• Prepare for global procurement and delivery of
  PrEP.
• Provide adequate financing.

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For More PrEP Information from AVAC

• Adapting to Realities Trends in HIV Prevention
  Research Funding, 2000 to 2008, HIV Vaccines and
  Microbicides Resource Tracking Working Group
  (AVAC, AMD, IAVI, UNAIDS) coming Monday, 20
  July 2009
• www.prepwatch.org
• The PrEP Implementation Puzzle Many missing
  pieces from AVAC Report 2009 Piecing Together
  the HIV Prevention Puzzle
• Anticipating the Results of PrEP Trials A
  powerful new HIV prevention tool may be on the
  horizon. Are we prepared?, 2008
• Will a pill a day prevent HIV? Anticipating the
  results of the tenofovir PrEP trials, 2005
• PrEP Factsheet, 2009

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About AVAC

• Founded in 1995, AVAC is an international,
  non-profit organization that uses education,
  policy analysis, advocacy and community
  mobilization to accelerate the ethical
  development and eventual global delivery of AIDS
  vaccines and other new HIV prevention options as
  part of a comprehensive response to the pandemic.
  
• We accept no government or pharmaceutical
  funding.
• www.avac.org