Microbicide and PrEP Overview GCM Adolescent Consultation Durban, South Africa 5-6 Sept, 2007 Craig M. Wilson Adolescent Medicine Trials Network for HIV/AIDS Interventions (ATN) University of Alabama at Birmingham

Interventions to Prevent HIV AVAILABLE –Behavior change (ABCs) –Condom promotion –MTCT interventions –IVDU risk reduction –STD control –Male circumcision –Post-exposure prophylaxis STILL UNPROVEN –Vaccination –Microbicides –Pre-exposure Prophylaxis –Female condoms –Treat infected partner with antiretrovirals –Abstinence only programs

Microbicides: Sites and Mechanisms Mucosal surfaces –Direct inactivation –Preservation of acidic environment –Enhancement/restoration of commensal flora –Physical barrier Tissue or Cell Surface –HIV cell receptors or co-receptors –Viral absorption or fusion Viral Surface –Polyanionic polymers or envelope interacting agents Inside Cell –Anti-retrovirals (Review: Lancet 369:787, 2007)

Microbicides: General Characteristics Potent against most HIV and other STIs Preserved activity in presence of seminal fluid No effect on integrity of mucosal surfaces No effect on commensal flora Preserve or enhance low vaginal pH Stable at tropical temperatures Compatible with latex Good acceptability: odor, color, taste, Easy to use, low cost, long shelf life

Microbicides: Trials candidates in development –One in Phase II/IIb and 3 in Phase III –11 in Phase I trials Nonoxynol (N-9) Trial –African and Thai sex workers –N-9 users with higher HIV infection rates (14.7 vs 10.3 per 100 person years) –Evidence of increased mucosal irritation

Microbicides: Trials 2 Cellulose Sulfate (Ushercell) –Polyanion with broad STI activity –3 Phase I and a Phase II trial with promising results –Two Phase III trials stopped in 2007 when the multi-country trial showed evidence of increased risk MIRA Trial (Padian et al Lancet on line 13 July, 2007) –RCC trial comparing condom alone vs condom plus diaphragm with readily available lubricant gel in South Africa and Zimbabwe –N= 5045, age 18-49, follow up planned for up to 24 months –HIV incidence of 4.1% vs 3.9% per 100 woman years in the intervention vs control arms

Microbicides: Trials 3: Active BufferGel vs PRO % Phase IIb –6 country RCT (Malawi, S Africa, Tanzania, USA, Zambia, Zimbabwe) N=3220 PRO % vs 2.0% Phase III –6 country RCT, (Cameroon, S Africa, Tanzania, Uganda, Zambia, Swaziland) N = 11,920 Carragard Phase III –South Africa 3 sites RCT, N = 6270

Microbicides: Summary Multiple products in late phase trials but success needed in one of ongoing trials to demonstrate proof of concept Will ultimately need multiple products –extended daily use vs intermittent coitally dependent use –contraceptive vs non-contraceptive –product for rectal use

Adolescent Specific Issues for Microbicides: Biological vaginal ecology and flora alteration douching/cleansing activities of population physical maturation/ectopy (non-issue if sexually active) partner acceptability

Adolescent Specific Issues for Microbicides: Trial Design Phase I/II studies: –relatively intense biomedical sampling –need sexually active populations Screening-in approaches parental permission approaches Phase II “Bridging” Studies –“Bridging” design will depend on adult data

Pre-exposure Prophylaxis (PrEP) General proof of concept comes from animal studies and MTCT ART interventions Previously not considered because of ART toxicities or unfavorable pharmacokinetics Recent availability of ART with longer half-life and lower toxicity profiles and lack of success in other approaches have re-opened considerations

HIV Replication Cycle and Sites of Drug Activity Capsid proteins and viral RNA CD4 Receptor Viral RNA New HIV particles ProteaseReverse Transcriptase Unintegrated double stranded Viral DNA Integrated viral DNA Viral mRNA Integrase gag-pol polyprotein Attachment and Fusion UncoatingReverse Transcription IntegrationTranscription Translation Assembly And Release Protease Inhibitors NRTIs NNRTIs Nucleus Cellular DNA CCR5 or CXCR4 co-receptor HIV Virions Fusion Inhibitors Adapted:Levy JA. HIV and the Pathogenesis of AIDS. 2nd ed. Washington, DC: American Society for Microbiology; 1998:9-11.

PrEP Study Designs High risk populations with exposures for risk over defined period of time –Young females in southern Africa –Commercial sex workers –IVDU while engaging in care –Discordant couples –Young MSM in US Daily/continuous vs “coitally” dependent Single drug (tenofovir) vs combination (tenofovir/FTC, Truvada)

PrEP Studies: Active Botswana –male and female, age 18-29, daily tenofovir, N = 1200 Multi-country eastern/southern Africa –female, age >18, daily tenofovir India –MSM, age > 18, daily truvada Multi-country –discordant couples, age >18, truvada, vs tenofovir Multi-country eastern/southern Africa (development) –Vaginal tenofovir vs PrEP microbicide

PrEP Study: Proposed Multi-country eastern/southern Africa plus US –female, age 16-22, Africa –male MSM, age 16-22, US –episodic vs daily truvada

Adolescent Specific Issues for PrEP No biological issues Need sexually active populations screening in approaches parental permission approaches Need for behavioral studies around use patterns

Summary Plenty of Challenges !