Biomedical HIV prevention


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An overvew of biomedical strategies, modalities and challenges. This presentation was given at the 2008 AFAO HV Educators Conference.

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  • Biomedical HIV prevention

    1. 1. Biomedical HIV prevention Bridget Haire
    2. 2. This presentation…. <ul><li>Describe the modalities of biomed prevention; </li></ul><ul><li>Show the research processes and timelines involved; </li></ul><ul><li>Discuss the major challenges in the area, with an emphasis on the Australian epidemic; </li></ul>
    3. 3. Food for thought…. <ul><li>We need a range of HIV prevention options, because one size doesn’t fit all. (Do we?)‏ </li></ul><ul><li>Unless the community sector gets behind the new technologies, we risk being like the Catholic Church on birth control. (Is this fair?)‏ </li></ul><ul><li>We cannot continue to spruik the condom when people want a range of options and are willing to live with increased risk. </li></ul>
    4. 4. The modalities <ul><li>Proven </li></ul><ul><li>Mother-to-child (combination of interventions, including behavioural)‏ </li></ul><ul><li>Circumcision partially effective ~60% male partners in insertive vaginal intercourse </li></ul><ul><li>PEP (post-exposure prophylaxis) – partially 79% </li></ul><ul><li>Experimental </li></ul><ul><li>Microbicides (vaginal and rectal)‏ </li></ul><ul><li>Pre-exposure prophylaxis </li></ul><ul><li>Vaccines </li></ul><ul><li>STI treatment/herpes suppression </li></ul><ul><li>Index partner treatment (reducing viral load to reduce transmission)‏ </li></ul>
    5. 5. Definitions <ul><li>A microbicide is an agent applied topically to prevent HIV (or other STI) infection; use may or may not be coitally dependent; </li></ul><ul><li>PrEP is the use of antiretroviral drug/s prior to exposure to prevent HIV infection; </li></ul><ul><li>Vaccines are agents introduced into the immune system that ‘teach’ the immune system to repel a particular infection. </li></ul>
    6. 6. Vaccines <ul><li>Vaccines are the ideal technology (if they are cheap enough, easy to transport, and don’t require refrigeration; </li></ul><ul><li>Because scientists do not know which parts of the immune system need to be engaged, and how, to protect against HIV, testing HIV vaccines is a laborious process of trial and error; </li></ul><ul><li>It’s impossible to out a timeframe onto vaccine development. May be decades. </li></ul>
    7. 7. HIV Prevention Trial Design (Sharon Hillier, PM2008)‏ Randomisation Active Drug 1 Placebo Active Drug 2 Safe sex counseling Diagnosis & treatment of STIs Condom provision Primary Endpoint HIV seroconversions
    8. 8. What happens to seroconverters? <ul><li>Increased scrutiny to unsure that ARV treatment is available, alongside other treatment that might be required . </li></ul><ul><li>This is achieved through links to treatment programs (in developing country contexts)‏ </li></ul><ul><li>How well such linkages work is also being scrutinised - things like MoUs being developed </li></ul><ul><li>The question of who is responsible has shifted to a more practical one of how to achieve it. </li></ul>
    9. 9. Anticipated Prevention Trial Results [slide from FHI] 2006 2008 2009 Female Barrier- Diaphragm Male Circumcision - Susceptibility 2010 2007 Microbicides – CS-1 CS-2 Carraguard Male Circumcision - Infectiousness <ul><li>Microbicides </li></ul><ul><li>BG/Pro2000 </li></ul><ul><li>Pro2000 </li></ul><ul><li>TDF </li></ul>Oral PrEP - IDU HSV-2 Treatment - Infectiousness HSV-2 Treatment – Susceptibility <ul><li>Oral PrEP </li></ul><ul><li>MSM </li></ul><ul><li>Heterosexual </li></ul>2012 Index Partner Treatment Vaccines - Adenovirus-1 Adenovirus-2 Vaccines - Prime/Boost Community VCT and HIV Support Oral PrEP - West Africa Microbicides – SAVVY
    10. 10. Actual Trial Results 2006 2008 2009 Female Barrier- Diaphragm No benefit shown Male Circumcision – Susceptibility Success!! 2010 2007 Microbicides – CS-1 CS-2 Carraguard No effect on HIV infection Male Circumcision - Infectiousness <ul><li>Microbicides </li></ul><ul><li>BG/Pro2000 </li></ul><ul><li>Pro2000 </li></ul><ul><li>TDF </li></ul>Oral PrEP – IDU Oral PrEP MSM US HSV-2 Treatment - Infectiousness HSV-2 Treatment – Susceptibility Didn’t decrease HIV transmission <ul><li>Oral PrEP </li></ul><ul><li>MSM (TDF+ FTC)‏ </li></ul><ul><li>Heterosexual (TDF; TDF+ FTC)‏ </li></ul>2012 Index Partner Treatment Vaccines - Prime/Boost Community VCT and HIV Support Oral PrEP - West Africa Statistically insignificant result Microbicides – SAVVY Failed: futility Vaccines - Adenovirus-5 Adenovirus-5 Trial halted: More infections in vaccine arm ORAL PrEP TDF; TDF+ FTC Kenya Uganda (serodisco) FEM Prep Africa Women TDF+ FTC Microbicide/PrEP VOICE study Women TDF; TDF+FTC; TDF gel Microbicides MTN 115-116; (preg)‏
    11. 11. Within the next two years… <ul><li>We will be seeing results from 3 microbicide and 3 PrEP studies. </li></ul><ul><li>Microbicide results, while very significant, won’t have much impact here; PrEP results will be of significant interest (condom-free sex?). </li></ul><ul><li>We need to be prepared to respond to media, to debate issues of access and licensure, to consider whether PrEP may be useful for a niche population. </li></ul>
    12. 12. Why PrEP results require preparation <ul><li>The likelihood is there will be a degree of efficacy and a rate of adverse events (Tues); </li></ul><ul><li>Individual acceptability, cost effectiveness estimations and general community values may all differ. There will be moral concerns. </li></ul><ul><li>User-pays brings equity concerns; </li></ul><ul><li>People with intellectual disabilities may need to be considered separately; </li></ul><ul><li>PrEP in gay communities is likely to be seen as an alternative, not a belt-and-braces approach. </li></ul><ul><li>Decreasing in condoms will increase STI. </li></ul><ul><li>‘ Partial efficacy’ is a very difficult concept. </li></ul>
    13. 13. What does ‘partially effective’ mean? <ul><li>Makes sense applied to population; harder when you are thinking about individuals. </li></ul><ul><li>Risk reduction per act where there is exposure? (Often don’t know when there is exposure.)‏ </li></ul><ul><li>Usefully conceived as producing a delay in infection (example). But this presumes that infection is inevitable. </li></ul><ul><li>If STI increase, might this cancel out the ‘partial efficacy’? </li></ul>
    14. 14. PrEP and ARV resistance <ul><li>There will be PrEP-takers who seroconvert. </li></ul><ul><li>How will this be diagnosed? (ie how will people on PrEP be monitored for HIV etc)? </li></ul><ul><li>Continuing to take PrEP after seroconversion is likely to cause drug resistance to a good 1 st line ARV drug (less so if a combined PrEP is used). </li></ul><ul><li>The resistance issue will also to apply with microbicides that use ARVs to prevent infection. </li></ul>
    15. 15. Unknowns in PrEP <ul><li>Whether episodic PrEP might work; (needs a trial)‏ </li></ul><ul><li>Whether a 110kg man from the Netherlands requires the same dosage as a 45kg women from Thailand; (needs a trial)‏ </li></ul><ul><li>How people might think about using PrEP as part of a risk reduction strategy (needs qualitative research)‏ </li></ul>
    16. 16. Conclusion <ul><li>Despite the recent history of biomedical prevention trials failing or showing interventions not working, the focus remains. </li></ul><ul><li>As a sector, we need to get to grips with the concept of partial efficacy and what is means for risk reduction in practice. </li></ul><ul><li>We need to advocate for the research we need to answer critical questions in the field. </li></ul>