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State of Global Rectal Microbicide Research Ian McGowan MD PhD FRCP Magee-Womens Research Institute University of Pittsburgh
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Microbicides are products that can be applied to the vaginal or rectal mucosa with the intent of preventing or significantly reducing the risk of acquiring STIs including HIV
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McGowan I, Biologicals, 2006 Microbicide Mechanism of Action
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Rationale for Rectal Microbicides Unprotected receptive anal intercourse (RAI) is the highest risk sexual activity for HIV transmission Men and women in the developed and developing world practice RAI Murine and non human primate studies have shown proof of concept that rectal application of ARV microbicides can prevent SIV/HIV infection
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Lubricants As a Drug Delivery System
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MSM Developed World Women Developing World
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Clinical Development of Rectal Microbicides
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Phase 1 Studies
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Early Nonoxynol-9 Studies Low-dose N-9 gel was not associated with macroscopic rectal and penile epithelial disruption or inflammation, but histologic abnormalities were commonly observed during N-9 gel as well as during placebo gel use. Tabet S et al. Sex Trans Dis 1999 2% N-9 showed rapid exfoliation of the rectal epithelium. Phillips D et al. Contraception 2004
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HPTN 056 Study Design Screening Week- 20 + 2+ 4 BaselineWeek 2Week 4 Consent Physical Anoscopy Rectal GC/CH HIV Ab CD4 / Viral load Sigmoidoscopy Intestinal biopsy at 10cm and 30cm Cell isolation and flow cytometry Tissue cytokines Rectal immunoglobulins Tissue / rectal secretion viral load McGowan et al. JAIDS 2007
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UC781 Trial Design Screening EnrollmentRandomization 0.1% 0.25% Placebo Baseline Endoscopy Single dose 2 nd Endoscopy 7 single Doses 3 rd Endoscopy Anton P et al. PLoS ONE 2011
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Explant Data (TCID 50 10 2 ) HEC PlaceboUC781 0.10%UC781 0.25% 10cm 30cm V2: Baseline; V3: 30 minutes post single dose
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Oral or Topical ARV PrEP? Oral Topical Concentration of ARV BloodMucosa
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RMP-02/MTN-006 Baseline Evaluation Open label Oral tenofovir (N = 18) Single rectal tenofovir (N = 18) 2:1 7 Day Rectal tenofovir (N = 18) 2:1 Safety, PK / PD, acceptability Anton et al. CROI 2011
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Rectal Acceptability of Vaginal Tenofovir
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Pharmacokinetics in Tissue Concentration of TVF-DP (fmol/mg) RouteOralRectal (S)Rectal (7D) N Detectable7/1810/1212/12
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PK/PD Relationship
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Mucosal Safety in RM Trials Epithelial sloughing Histopathology Mucosal mononuclear cell phenotype Mucosal cytokine mRNA Luminex Microarray gene expression Fecal calprotectin Rectal microflora N-9 PRÉ
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MTN-007 N=60 HEC (N=15) 1% Tenofovir (N=15) 2% N-9 (N=15) Single dose 7 day daily doses 7-14 day interval Endoscopy Safety/behavioral assessment Screening No Treatment (N=15) Baseline Evaluation 7-14 day interval
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DAIDS Integrated Preclinical Clinical Program for HIV Topical Microbicides
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Microbicide Development Program First IPCP focusing on rectal microbicide development Provided proof of concept in the SIV NHP model and development of explant platform Phase 1 clinical trials of the vaginal formulation of tenofovir gel UC781 (RMP-01) Tenofovir (RMP-02/MTN-006) Behavioral correlates of RAI Anton: IPCP U19 AI060614 / August 2004
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CHARM Program Combination HIV Antiretroviral Rectal Microbicide Program NIAID/DAIDS Integrated Preclinical Clinical Program Consortium University of Pittsburgh UCLA Johns Hopkins UNC CONRAD / Gilead McGowan: IPCP U19 AI082637 / September 2009
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CHARM Program Overview Development of rectal specific ARV microbicides PK/PD evaluation in humanized mouse model Phase 1 studies Tenofovir Maraviroc Tenofovir & Maraviroc
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CHARM-01 Pre-Phase 1 single dose comparison of current formulations of tenofovir 1% gel: Vaginal formulation Reduced glycerin formulation Rectal specific formulation Endpoints General and mucosal safety PK/PD Current status Version 1.0
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CHARM-02 Pre-Phase 1 single dose comparison of current formulations of tenofovir 1% gel with and without simulated RAI Endpoints Pharmacokinetics Drug distribution using SPECT/CT imaging Current status Version 1.0
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Project Gel McGowan & Carballo-Dieguez: NICHD R01 / September 2009
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Microbicide Safety and Acceptability in Young Men NICHD R01 Pittsburgh, Boston, Puerto Rico Phase 1 safety and acceptability of tenofovir 1% gel Ethnically diverse MSM (18-30) Consensual RAI in last month Unprotected RAI in last year
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Microbicide Safety and Acceptability in Young Men Stage 1A Screening 240 MSM Consensual RAI in last month URAI in last year Stage 1B 3 month Acceptability & Adherence study with placebo gel 120 MSM RAI in last 3 months STI negative Stage 2 Phase 1 Tenofovir rectal safety study 42 MSM 80% adherence in Stage 1B
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Phase 2 Studies
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MTN-017 Phase 2 rectal safety study of tenofovir gel N = 210 International sites United States (3) Thailand (2) South Africa (1) Peru (1) Endpoints Safety Adherence Self report Objective measures Acceptability PK/PD
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MTN-017 12 weeks BL TNF Gel Daily TNF Gel ID Oral Truvada BL TNF Gel ID TNF Gel Daily Oral Truvada BL Oral Truvada TNF Gel ID TNF Gel Daily Mucosal PK/PD subset
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Phase 2B/3 Studies
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Combination Prevention SC ± Oral ± Rectal ± Vaginal Conventional HIV Prevention Package + PrEP ± HIV Vaccine
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iPrEx Study 2,499 MSM and male- to-female transgendered women randomized to Truvada or placebo 44% reduction in HIV acquisition Higher drug concentrations associated with increased protection Grant R et al. NEJM 2010
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TMC-278 LA Rilpivirine NNRTI IM Nanosuspension Potential for 1-3 month delivery Phase 1 PK/PD studies ongoing Colorectal explants Cervicovaginal explants MWRI-01* University of Pittsburgh Liverpool University *Funded by the Bill and Melinda Gates Foundation
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Arm 1 Arm 2 Arm 3 Arm 4 1200mg 600mg 900mg 1200mg + 900mg/ 3 monthly Possible Arm 5 Possible Arm 5/6 300mg/ 1 monthly 600mg/2 monthly Initial EnrollmentSecondary Enrollment ScreenBaseline+1+2+3+4+5 MWRI-01
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Effectiveness Study Designs Option 1: Tenofovir gel versus placebo + standard prevention package Option 2: Tenofovir gel versus placebo + standard prevention package + permission to use PrEP (HVTN 505) Option 3: Tenofovir gel versus placebo + standard prevention package + Truvada Option 4: Tenofovir gel versus Truvada versus TMC 278 LA + standard prevention package
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Sample Size Parameters Assumptions Incidence rate ~ 5% Effect size 60% Lower bound 25% Minimum FU 12 months Enrollment 300/month PrEP effect 46% Endpoints: 120 Option1 N = 2,400; FU 24 months Option 2 N = 2,400; FU 30 months Option 3 N = 2,400; FU 37 months
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The VOICE Trial Both oral and topical tenofovir arms stopped for futility Reasons for failure not yet known Non adherence Compartmental PK Biology Implications for rectal microbicide development?
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Rectal Microbicide Timeline* 201020112012201320142015201620172018 Phase 1 Phase 2 Phase 2B Review Available Vaginal microbicides *An approximation based on tenofovir 1% gel
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Summary Rectal microbicides are needed for men and women in the developed and developing world who are at risk of HIV associated with unprotected RAI RM development has moved from Phase 1 to Phase 2 PK/PD models should increase likelihood of success in Phase 2B/3 Planning for an RM effectiveness study needs to start now.
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Acknowledgements
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