Microbicides: State of the Art and Its Evolution Sharon L. Hillier, Ph.D. Professor Department of Obstetrics, Gynecology and Reproductive Sciences University of Pittsburgh Magee-Womens Hospital USA

Microbicides for Prevention of HIV-1 Transmission Shattock RJ and Moore JP. Nature Reviews Microbiology, vol. 1 Oct/2003

Microbicide Active HIV Activity Low toxicity In vitro Activity against other STI’s Activity against sperm +/-

HIV Activity Toxicity In vitro Activity against other STI Activity against sperm +/- Nonoxynol-9

The Road to Development l Scale-up manufacture of active molecules l Formulation l Pharmacokinetic and pharmacodynamic studies to identify how much active is available in the lumen and the epithelium l Phase 1, 2 and 3 clinical trials l Complexities of access (storage and cost)

LONG STRAIGHT ROAD

New Surface Active Agents H 2 CO (CH 2 ) 7 CH 3 C HOH C O H H 2 Octylglycerol (OG) Invisible condom Savvy™ (C31G)

Positive AttributesChallenges or Deficiencies Low costLow potency, narrow therapeutic index Contraceptive Activity against other STI’s (HSV 2, others) “Surfactant stigma” “Safe” profile in rectum (monkey model) Active in lumen only; restricted to coital dependent use Membrane Disruption Agents

l Newer surfactant agents identified having low toxicity and contraceptive potential l Savvy trial (USAID funded, FHI implementation) ongoing for prevention of HIV l CAP being developed by CDC and NIH l These agents have lower toxicity than N-9 and could replace N-9 as a topical contraception l A study comparing Savvy and Tenofovir gel vs. placebo is being planned by CAPRISA/FHI/CONRAD The State of the Art Membrane Disruption Agents

Acid/Buffering Agents Positive AttributesChallenges/Deficiencies Restores/maintains vaginal acidity and ecology Non-specific, thus low potency against HIV Low local toxicityOnly for coital-dependent use No systemic absorption In vitro activity against acid- sensitive STI’s (BV, HSV2, HPV, Ct, GC) Contraceptive*Lemon and lime juice are toxic and do not buffer effectively

The State of the Art Acid/Buffering Agents l May be used with cervical barriers for HIV and STI prevention l May replace N-9 for topical contraception l May be combined with other hi-potency microbicides as combination products

Fusion Inhibitors Carraguard PRO 2000 Cellulose sulfate

Fusion Inhibitors Positive AttributesChallenges or Deficiencies Low costLow potency against HIV Low potential for resistance Undefined activity against other STIs Many have activity against other enveloped viruses (HSV 2) Contraceptive potentialCoitally dependent

The State of the Art: Fusion Inhibitors l PRO 2000 in two effectiveness trials (HPTN 035 and MDP) l Cellulose sulfate in effectiveness studies (CONRAD and Gates, FHI funded by Gates and USAID) l Carraguard in late phase effectiveness studies (Pop Council) l These may be considered as secondary actives for combination products

ART’s Tenofovir UC-781 MIV TMC120 Molecular Structure of TMC120

ART’s Positive AttributesDeficiencies or Challenges High potencyNo activity against other STI’s Documented efficacy as therapeutics Risk of ART resistant virus Can be delivered orally or vaginally Some ART’s have poor systemic absorption Extensive preclinical/clinical data available Can be modified to other delivery forms, and possible to use independent of coitus

The State of the Art ART’s l Tenofovir being evaluated as oral agent for prevention of HIV l Tenofovir gel moving forward into expanded phase 2 testing (HPTN 059) l TMC 120 gel in expanded phase 2 testing (IPM) l TMC 120 vaginal ring in phase 1 (IPM) l Several NNRTI’s moving forward in early clinical studies, some incorporating sustained release technology l Richest pipeline of products ready to move into effectiveness studies

CCR5 Antagonists SCH-D GSK Aplaviroc Pfizer Maraviroc (UK ) SH-D Merck-167

CCR5 Antagonists Positive AttributesDeficiencies or Challenges High potency against R5 HIVSafety/toxicity signals when these agents used as therapeutics Long-term binding to CD4 (up to 5 days) Proven activity as HIV therapeutic Larger molecules (PSC- RANTES) may be expensive and difficult to formulate Proof-of-concept in simian model Concerns regarding selective pressure towards X4 Small molecule scale-up

The State of the Art CCR5 Antagonists l None of these agents are in human trials as topical microbicides to date l PSC-RANTES is being developed specifically for vaginal application- formulation challenges considerable l Merck 167 and two related molecules have recently been licensed and royalty-free for microbicide development (IPM) l CCR5 antagonists developed as therapeutics have had safety signals which may limit their further development as topical microbicides

GP120 Binders Cyanovirin-NDendrimers SPL BMS78806 BMS599,793

GP 120 Binders Positive AttributesDeficiencies or Challenges Activity against HSV 2 (dendrimer) Difficult/expensive to formulate (cyanovirin) Proof-of-concept in simian model (cyanovirin-rectally; dendrimers, vaginally) Coitally-dependent use but may be formulated for once-daily or in rings which will allow for non- coital use Plant expression systems may increase availability

The State of the Art GP120 Binders l Dendrimers (SPL, VivaGel) in phase 1 clinical trials and beginning studies for STI prevention l Cyanovirin formulation may be complex, being considered for delivery through genetically-modified organisms l BMS599, 793 recently licensed royalty- free for microbicide development (IPM)

Cervical Barrier Delivery Systems

Positive AttributesChallenges or Deficiencies Provide protection of cervix – likely benefit for prevention of cervicitis Higher unit cost ($.25) if used as applicator, multiple use systems may have acceptable costs Adaptable for use with different microbicide products Difficulty with insertion Familiar technology from contraceptive field Environmental challenges with disposal May “concentrate” formulation on target cells in cervix Local/mechanical irritation Replaces applicator

Current Status: l Phase 1 acceptability of Duet completed in early 2006 N=24, CONRAD l Post-coital testing (phase 1) for SILC’s completed 2005 The Future: l SILC moving to contraceptive effectiveness study with N-9 (CONRAD, USAID) non- comparative, to begin July 2006 Cervical Barrier Delivery Systems

Sustained Release Delivery Systems: Rings

Positive AttributesDeficiencies or Challenges Increase compliance and acceptability because coitally- independent More exposure to drug, greater potential for toxicity May be optimal method to deliver molecules active intracellularly Difficulty in ring insertion and placement Flexible platform for addition of antibacterial or contraceptive drugs Optimal method for induction of resistance if patient seroconverts on product

Sustained Release Delivery Systems: Rings l Current Status » Multiple technologies being evaluated –Reservoir and matrix type –Phase I trials with reservoir type rings with TMC120 demonstrated safety and good tissue levels (IPM) » New ring technologies in development –Biodegradable; multi-drug delivery capable; hydrophilic drug compatible, etc.

Genetically Modified Bacteria

Genetically Modified Live Organism Vectors Positive AttributesChallenges or Deficiencies Potential for “continuous release” of molecules which bind HIV (CD4, cyanovirin) “Competitive fitness” relative to endogenous flora Extensive microbiological “proof-of- concept” Concerns regarding genetically modified organisms Potential for use independent of coitus Difficult to predict success in achieving sustained colonization Nearly impossible to ensure delivery of therapeutic/prophylactic dose Potential for inducing immune response (to organism or secreted protein)

Current Status: Lactobacillus l Lactobacillus sCD4 and 17b hybrid protein developed by Dr. Ed Berger, Chief of NIAID Laboratory of Viral Disease l Lactobacillus has been genetically modified to express sCD4 and 17b by Osel l Cyanovirin-N, an antiviral protein developed at NCI has also been expressed in Lactobacillus l Some animal studies underway for Lactobacillus expressing these protein Genetically Modified Live Organism Vectors: Lactobacillus

Current Status: E. coli l Dean Hamer (NCI Biochemistry Lab) has genetically engineered a strain of E. coli to secrete an antiviral peptide in the gut l HIV C-peptide binds to gp 41 l Capacity of this genetically modified organism to colonize the mouse gut following ampicillin treatment documented l Similar model studies with SHIV challenge underway Genetically Modified Live Organism Vectors: E. coli

Combination Products Positive AttributesDeficiencies or Challenges Combinations a proven therapeutic approach for HIV treatment Formulation complexity enormous Lower risk of “breakthrough” infections Current FDA regulatory pathway requires combination products to be evaluated as A vs. B vs. A+B Lower risk of ART resistance developing Huge trials and difficult to power to detect differences between A vs. A+B Slow release technology possible Expensive/complex licensing issues

The State of the Art Combinations l Combinations of cervical barriers and non- specific microbicides will be the first combinations available if proven efficacious l Combinations based on acid buffer gels with a hi-potency active can be developed with low regulatory barrier because of formulation excipients that can be used l Combining hi-potency actives will be challenging, but preliminary animal model studies have confirmed the feasibility of this approach

HIV Activity Toxicity In vitro Activity against other STI Activity against sperm +/- Microbicide Active Early consideration of Pharmacology Early consideration of formulation challenges

The State of the Art of Microbicides l In the pipeline of microbicide candidates there is a broad diversity in mechanism of action l Each of the approaches has significant strengths and challenges l The near-term pipeline of molecules ready to enter phase 1 testing is modest and should be expanded rapidly l Need to better define the TARGET for each active and whether the ACTIVE can be successfully delivered to the target

Acknowledgements l Ian McGowan l Zeda Rosenberg l Ward Cates l Joe Romano l Fulvia Veronese l Saliya Senevirantne l Marianne Callahan l Larry Severy l Ed Tramont l Lisa Rohan