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Future HIV Prevention Trials: Sexual Transmission

Future HIV Prevention Trials: Sexual Transmission. Willard Cates, Jr., MD, MPH Family Health International. 3 rd IAS Conference Rio de Janeiro July 26, 2005. Key Topics. HIV prevention tools Current trials Future opportunities Future challenges. HIV Prevention Research - Why.

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Future HIV Prevention Trials: Sexual Transmission

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  1. Future HIV Prevention Trials:Sexual Transmission Willard Cates, Jr., MD, MPH Family Health International 3rd IAS Conference Rio de Janeiro July 26, 2005

  2. Key Topics • HIV prevention tools • Current trials • Future opportunities • Future challenges

  3. HIV Prevention Research - Why • Continued spread of HIV • Clear moral imperative to conduct prevention science

  4. Prevention Subjects are relatively healthy, asymptomatic Low morbidity and mortality Long time frame Sample sizes large Community base of research Industry support is unusual due to no profitable market Therapeutic Subjects have defined diseases or conditions Substantial morbidity/mortality Short time frame Sample sizes modest Clinical base of research Industry support is common due to profitable market Prevention vs. Therapeutic Research: Contrasts

  5. Efficacy and Effectiveness - Two Levels

  6. Contraceptive Pregnancy Rates Spermicides Diaphragm w/spermicides Female condom Male condom Oral Contraceptives IUD (TCu-380A) Rate during perfect use Female/male sterilization Rate during typical use Norplant/Depo-Provera 0 10 20 25 5 15 Percent of Women Pregnant in First Year of Use Source: Trussell (2004); NCHS (2005)

  7. HIV Prevention Tools - Infection Rates Microbicides Diaphragm Female condom Male condom Oral Acyclovir Oral ARV Rate during perfect use Male circumcision Rate during typical use Vaccines 0 40 60 80 20 Percent of Persons Infected after a Decade of Use

  8. Topical Microbicides –2nd Generation Products • Buffergel * • Pro2000 • C31G * • Cellulose sulfate • Carraguard * May also protect against pregnancy

  9. Diaphragm • RCT in Zimbabwe, RSA • Diaphragm plus lubricant gel vs. condom • 4,500 participants planned, 86% enrolled • Results expected 2007

  10. Female Condoms • Biologic plausibility similar to male condoms • If made available, lowers overall level of unprotected acts • Emerging evidence (’05 ISSTDR) on STD prevention

  11. Oral Acyclovir Prophylaxis • Acquisition – HSV+, HIV- subjects – HPTN 039 – USA and global – 3,000 participants – MSM, MSW – Results expected 2007 • Transmission – HSV+, HIV+ subjects – Gates – US and global – 3,600 HIV discordant couples – Results expected 2008

  12. Oral ARV Pre-exposure Prophylaxis • Tenofovir collaboration – researchers and stakeholders • Focus for prevention trial ethics • Multiple populations globally • Estimated cumulative 4000 participants • Incremental results from summer 2006

  13. ARV Treatment as Prevention • Viral load importance • HPTN 052 – 8 sites, 5 countries • Pilot phase initiated • Full trial – spring 2006, 1,760 discordant couples planned

  14. Male Circumcision • RSA data - encouraging – 70% protection – Data presented at IAS • Kisumu, Kenya – 2,700 participants – Results expected 2007, DSMB driven • Rakai, Uganda – 5,000 participants – Results expected 2007, DSMB driven

  15. Future Directions • 3rd generation microbicides • Newly designed barriers • Combination ARV pre-exposure • Acute HIV infection

  16. Transmission Efficiency

  17. Early HIV Infection: A Triple Whammy Sources: Cates (1997), Wawer (2005)

  18. Future Challenges • Participant care/treatment • Standards of preventive care • Community engagement • Product interruption • Additional study sites

  19. Product Interruption – 3Ps • Participants – adherence • Politics – Cambodia, Cameroon • Pregnancy – depends on • Coital frequency • Contraceptive use • Testing frequency/methods

  20. Pregnancy Rates – Microb Prep (NIAID) * Per 100 person years

  21. Pregnancy Rates – Savvy Ghana (USAID) * Per 100 person years

  22. HIV Prevention Trials – 2004-2010 What Numbers Do We Need? Partial Source: Wasserheit (2003)

  23. Conclusion – HIV Prevention Trials, 2005-2010 • Current Phase IIIs essential • More site capacity needed • Collaboration with other fields useful – vaccine, circumcision, STD rx, etc. • Shared resources helpful • GCP training • Laboratory assessment • Research staff • Ethics standards • Community involvement • Design challenges

  24. Judy Auerbach Michael Cassell Mike Cohen Helene Gayle Ron Gray King Holmes Cynthia Kay Nancy Padian Renee Ridzon Ken Schulz James Trussell Sten Vermund Judy Wasserheit Gary West Thanks To

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