CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

Background: Griffithsin (GRFT), a 121- amino acid dimeric lectin from Griffithsia sp. (red algae), is a recently discovered protein with potent antiviral activity against both CXCR4- and CCR5-tropic HIV-1. It binds tightly to HIV envelope glycoproteins, preventing viral entry into cells as well as cell-to-cell virus transmission. We are developing an oxidation-resistant variant of GRFT (Griffithsin-M78Q/ Q-GRFT) as a topical microbicide to protect people at risk due to condomless receptive anal intercourse (CRAI) Because of its protein nature, Griffithsin may be susceptible to protease enzymatic degradation and its activity may be affected by host- and microbiome-derived compounds in the rectum. The activity of Q-GRFT in the rectal environment remains unknown. Methods: Six mouse and six human (HIV negative) rectal fluid samples were assessed for pH using MColorpHastTM strips, protein concentration by the bicinchoninic acid (BCA) assay, and protease activity by the casein colorimetric method. Q-GRFT activity (gp120 binding) was evaluated in rectal fluid and seminal plasma samples by enzyme-linked immunosorbent assay (ELISA). The growth inhibitory effects of Q-GRFT on the rectal microbiome components L. acidophilus, L. casei, and E. coli K12 were assessed by growth in broth media. Minimum Inhibitory Concentrations (MICs) were determined for Q-GRFT activity against C. trachomatis ATCC# VR348B Serovar E and N. gonorrhea ATCC#19424. Results: The human rectal fluid had pH 7-8, protein concentration of 730-1211 µg/mL and protease activity of 0.237-1.069µg/mL trypsin. In the mouse rectal fluid, protein concentration was 275-1565 µg/mL while protease activity was 0.443-30.15µg/mL trypsin. Q-GRFT remained active in rectal and seminal fluids. Q-GRFT at 0-0.2 mg/mL did not inhibit growth of L. acidophilus, L. casei or E. coli. It was inactive against C. trachomatis and N. gonorrhea at concentrations of up to 50μg/mL in contrast to the control antibiotics doxycycline and penicillin, respectively (MIC of both, 0.03μg/mL). Conclusion: Griffithsin-M78Q is stable in the rectal environment despite the protease activity detected in rectal fluids. It does not inhibit the rectal microbiome components L. acidophilus, L. casei and E. coli, or the pathogenic bacteria N. gonorrhea and C. trachomatis. Overall, Q-GRFT maintains its ability to bind and inactivate HIV in the presence of rectal fluids and seminal plasma while preserving the resident microbiome population. 1059LBEARLY TERMINATION OF A PHASE 1 TRIAL OF TENOFOVIR DISOPROXIL FUMARATE VAGINAL RING Marla J. Keller 1 , Laurie Ray 2 , Jessica M. Atrio 2 , Lilia Espinoza 1 , Shada Sinclair 1 , Jessica Goymer 1 , Mark A. Marzinke 3 , Bruce Frank 4 , Peter L. Anderson 5 , Jeanne Marrazzo 6 , Nelly R. Mugo 7 , Craig W. Hendrix 3 , Betsy Herold 1 1 Albert Einstein College of Medicine, Bronx, NY, USA, 2 Montefiore Medical Center, Bronx, NY, USA, 3 Johns Hopkins University, Baltimore, MD, USA, 4 Particle Sciences, Bethlehem, PA, USA, 5 University of Colorado, Aurora, CO, USA, 6 University of Alabama at Birmingham, Birmingham, AL, USA, 7 Partners in Health Research and Development, Thika, Kenya Background: A tenofovir disoproxil fumarate (TDF) polyurethane reservoir intravaginal ring (IVR) provided complete protection against SHIV in macaques and was well tolerated in sexually abstinent women with 2 weeks (wks) of continuous use. The objectives of this single blind, two-site, placebo controlled trial were to evaluate safety and PK of 3 months (mos) use of TDF IVR in sexually active (minimum of 4 sex acts/mo) women who were using contraception. Methods: Women were randomized 3:1 to TDF or placebo with ring changes monthly and study visits every 2 wks. DAIDS grading tables were used to assess adverse events (AEs). Drug concentrations were measured in cervicovaginal fluid (CVF) obtained by swab, cervical tissue, plasma, dried blood spots (DBS) and in rings after use. Cytokines/chemokines were quantified in CVF and compared between baseline and Day 28-30 in each group. Results: 17 of 40 planned women were enrolled (12 TDF, 5 placebo) before study termination. Only 2 TDF participants completed the study; 8 stopped ring use early due to Grade 1 vaginal ulceration near the ring, which occurred on average (avg) 32 days after ring use (range 23-56) and we elected to remove rings early in the other 2 (day 20 and 23) due to the AEs observed in 8 participants. 4 of the 8 women were symptomatic and 3 had bilateral ulcers. All of the ulcers resolved. None of the women in the placebo arm developed ulcers and 4 of 5 completed the study; 1 stopped early (day 67) due to travel. Contraceptive method and frequency of sex did not differ between the groups or in women with or without ulcers. Median (IQR) CVF TFV, tissue TFV-DP and DBS TFV-DP at Day 28-30 were 9 x 10 4 ng/mL (4 x 10 4 , 1 x 10 5 ), 301 fmol/mg (203, 347) and 669 fmol/punch (473, 883). CVF TFV levels did not differ at 2 versus 4 wks after ring use and were similar to levels observed in the previous 2-wk

study in sexually abstinent women. Avg in vivo TDF release rate was 7 ± 1.3 mg/ day based on residual drug levels in rings. 10 of 14 CVF inflammatory mediators were significantly higher at Day 28-30 compared to baseline in the TDF arm; no placebo arm changes were observed (p<0.05, paired t-test). Conclusion: Genital ulceration was observed with sustained TDF, but not placebo ring use, in sexually active women. Sustained levels of intracellular TFV-diphosphate or other metabolites may interfere with epithelial repair and/ or induce inflammation, which in the setting of microabrasions associated with ring use and/or sex may predispose to ulceration.

1060LBHYPO-OSMOLAR RECTAL ENEMA TFV FORMULATION PREVENTS SHIV ACQUISITION Peng Xiao 1 , Sanjeev Gumber 2 , Mark A. Marzinke 3 , Abhijit Date 3 , Thuy Hoang 3 , Justin Hanes 3 , Laura Ensign 3 , Lin Wang 4 , Lisa C. Rohan 4 , Richard Cone 3 , Edward J. Fuchs 3 , Craig W. Hendrix 3 , Francois Villinger 1 1 University of Louisiana at Lafayette, Lafayette, LA, USA, 2 Emory University, Atlanta, GA, USA, 3 Johns Hopkins University, Baltimore, MD, USA, 4 Magee–Womens Research Institute, Pittsburgh, PA, USA Background: Oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate/ emtricitabine (TDF/FTC) has been approved for prophylaxis of HIV-1 transmission, but is associated with systemic adverse effects, high cost, and low adherence in some populations. Protection from rectal transmission of HIV using topical microbicides that are congruent with sexual behavior, e.g., medicated lubricants and douches, offer the promise of improved adherence and lower cost while limiting systemic toxicity. Sodium based hypo-osmolar enemas have been shown to protect the colon epitheliumwhile at the same time promote the uptake of hydrophilic drugs by the tissue. We have therefore incorporated tenofovir (TFV) into two enema formulations and tested whether these formulations protect macaques from rectal SHIV acquisition. Methods: Daily oral TDF (22 mg/Kg) and two enema formulations (5.28 mg/mL in iso-osmolar [IOsm] or hypo-osmolar [HOsm] saline) were compared for TFV pharmacokinetics and efficacy at preventing rectal SHIV acquisition by rhesus macaques following repeated weekly challenges with ~103 TCID50 SHIV162p3. Macaques were challenged one hour following the weekly enema dose or oral daily dose. Results: Oral TDF achieved similar peak plasma TFV levels (~110 ng/mL) as rectal HOsm. One hour after rectal HOsm dosing, mean colorectal tissue homogenate TFV-DP was 4,784 fmol/mg (+/- 1366) at one hour, >6 times the IOsm dose at 1 (714+/-378) and 24 hours (448+/-133), the estimated steady- state daily oral TDF colorectal TFV-DP concentrations being 849 fmol/mg. When evaluated for efficacy after 8 weekly SHIV challenges, the greatest protection was seen with the HOsm TFV enema which protected 5/6 monkeys (p=0.004, when comparing HOsm to all other survival curves). Oral TDF protected 3/6 macaques, IOsm TFV protected 1/6 macaques, and none of the controls were protected (Figure). Conclusion: A single dose TFV HOsm enema delivered one hour before rectal SHIV challenge provided a high level of protection, superior to oral TDF and an IOsm enema of similar dose. In an ongoing clinical study of the same TFV HOsm formulation, colorectal tissue TFV-DP concentrations overlap monkey concentrations throughout 24 hours after dosing. This macaque study demonstrates the protective effect of a topically applied, episodic form of PrEP for clinical evaluation as a potential alternative to oral PrEP.

Poster Abstracts

CROI 2018 406