Efficient treatment and pre-exposure prophylaxis in rhesus macaques by an HIV fusion-inhibitory lipopeptide.

Two HIV fusion-inhibitory lipopeptides (LP-97 and LP-98) were designed with highly potent, long-acting antiviral activity. Monotherapy using a low dose of LP-98 sharply reduced viral loads and maintained long-term viral suppression in 21 SHIVSF162P3-infected rhesus macaques. We found that five treated monkeys achieved potential posttreatment control (PTC) efficacy and had lower viral DNA in deep lymph nodes, whereas monkeys with a stable viral rebound had higher viral DNA in superficial lymph nodes. The tissues of PTC monkeys exhibited significantly decreased quantitative viral outgrowth and fewer PD-1+ central memory CD4+ T cells, and CD8+ T cells contributed to virologic control efficacy. Moreover, LP-98 administrated as a pre-exposure prophylaxis (PrEP) provided complete protection against SHIVSF162P3 and SIVmac239 infections in 51 monkeys via intrarectal, intravaginal, or intravenous challenge. In conclusion, our lipopeptides exhibit high potential as an efficient HIV treatment or prevention strategy.

Safety and efficacy of the HIV-1 attachment inhibitor prodrug fostemsavir in heavily treatment-experienced individuals: week 96 results of the phase 3 BRIGHTE study.

BACKGROUND: Fostemsavir, a prodrug of the first-in-class attachment inhibitor, temsavir, is indicated for heavily treatment-experienced individuals with multidrug-resistant HIV-1. We previously reported superior efficacy of fostemsavir versus placebo in the randomised cohort of the BRIGHTE study after 8-day functional monotherapy (primary endpoint); here we report planned interim analyses through week 96. METHODS: BRIGHTE (NCT02362503) is an ongoing multicentre, two-cohort, phase 3 trial, done at 108 centres in 22 countries. We enrolled heavily treatment-experienced adults (≥18 years) failing antiretroviral therapy (HIV-1 RNA ≥400 copies per mL) into two cohorts: the randomised cohort, in which patients with one or two fully active antiretrovirals remaining received oral fostemsavir (600 mg twice a day) or placebo in combination with their failing regimen for 8 days, followed by fostemsavir plus optimised background therapy; or the non-randomised cohort, in which patients with no remaining antiretroviral options received oral fostemsavir (600 mg twice a day) plus optimised background therapy from day 1. Endpoints for the week 96 interim analyses included the proportions of participants with plasma HIV-1 RNA of less than 40 copies per mL, changes from baseline in CD4 cell counts, and the frequency of adverse events, adverse events leading to discontinuation, and deaths. The intention-to-treat exposed population and the safety population both included all participants who received at least one dose of study treatment. The response rates (proportion of participants with HIV-1 RNA <40 copies per mL) in the intention-to-treat exposed population were calculated via snapshot analysis at weeks 24, 48, and 96. FINDINGS: Between Feb 23, 2015, and Aug 11, 2016, 371 participants were enrolled and treated, of which 272 participants were in the randomised cohort and 99 in the non-randomised cohort. 320 (86%) of 371 reported a history of AIDS. In the randomised cohort, rates of virological suppression (HIV-1 RNA <40 copies per mL) increased from 53% (144 of 272) at week 24 to 60% (163 of 272) at week 96. Response rates in the non-randomised cohort were 37% (37 of 99) at week 24 and week 96. Mean increases in CD4 counts from baseline at week 96 were 205 cells per µL (SD 191) in the randomised cohort and 119 cells per µL (202) in the non-randomised cohort. Mean CD4/CD8 ratio increased from 0·20 at baseline to 0·44 at week 96 in the randomised cohort. Few adverse events led to discontinuation (26 [7%] of 371). 12 (4%) of 272 people in the randomised cohort and 17 (17%) of 99 in the non-randomised cohort died; the median baseline CD4 count for participants who died was 11 cells per µL. INTERPRETATION: In heavily treatment-experienced individuals with advanced HIV-1 disease and limited treatment options, fostemsavir-based antiretroviral regimens were generally well tolerated and showed a distinctive trend of increasing virological and immunological response rates through 96 weeks; these findings support fostemsavir as a treatment option for this vulnerable population. FUNDING: ViiV Healthcare.

Addition of Maraviroc Versus Placebo to Standard Antiretroviral Therapy for Initial Treatment of Advanced HIV Infection: A Randomized Trial.

Background: Patients diagnosed with advanced HIV infection have a poor prognosis despite initiation of combined antiretroviral therapy (c-ART). Objective: To assess the benefit of adding maraviroc, an antiretroviral drug with immunologic effects, to standard c-ART for patients with advanced disease at HIV diagnosis. Design: Randomized controlled trial. (ClinicalTrials.gov: NCT01348308). Setting: Clinical sites in France (n = 25), Italy (n = 5), and Spain (n = 20). Participants: 416 HIV-positive, antiretroviral-naive adults with CD4 counts less than 0.200 × 109 cells/L and/or a previous AIDS-defining event (ADE). Intervention: C-ART plus placebo or maraviroc (300 mg twice daily with dose modification) for 72 weeks. Measurements: The primary end point was first occurrence of severe morbidity (new ADE, selected serious infections, serious non-ADE, immune reconstitution inflammatory syndrome, or death). Prespecified secondary outcomes included primary outcome components, biological and pharmacokinetic measures, and adverse events graded 2 or higher. Results: 409 randomly assigned participants (207 in the placebo group and 202 in the maraviroc group) who received more than 1 dose were included in the analysis. During 72 weeks of follow-up, incidence of severe morbidity was 11.1 per 100 person-years in the maraviroc group and 11.2 per 100 person-years in the placebo group (hazard ratio, 0.97 [95% CI, 0.57 to 1.67]). Incidence of adverse events graded 2 or higher was 36.1 versus 41.5 per 100 person-years (incidence rate ratio, 0.87 [CI, 0.65 to 1.15]). Limitations: Sixty-four participants discontinued therapy during follow-up. The study was not designed to evaluate time-dependent outcomes or effect modification. Conclusion: Addition of maraviroc to standard c-ART does not improve clinical outcomes of patients initiating therapy for advanced HIV infection. Primary Funding Source: INSERM-ANRS (French National Agency for Research on AIDS).

Efficacy and safety of long-term maraviroc use in a heterogeneous group of HIV-infected patients: A retrospective cohort study.

Since the registration of maraviroc (MVC) as an antiretroviral agent in 2008, only studies with a follow-up time of <5 years have been published. Therefore, little is known about its long-term safety and efficacy in clinical practice. In this cohort study, data on long-term follow-up of MVC treatment in routine practice were analysed. A retrospective cohort study was conducted at University Medical Centre Utrecht with a follow-up period up to almost 10 years. The efficacy and tolerability of MVC-containing antiretroviral therapy (ART) was analysed in human immunodeficiency virus type 1 (HIV-1)-infected patients. The cohort consisted of 111 HIV patients who were treated for a median of 11.0 years (IQR 4.0-15.0 years) and with a median of 4 (IQR 2-6) previous ART regimens. The median time of MVC use was 49 months (IQR 21-82 months). Mean CD4+ T-cell counts continued to increase up to 9 years following initiation of MVC. Patients with a detectable viral load (≥50 copies/mL HIV-RNA) at the start of MVC-containing ART reached high proportions of viral suppression. Only three patients (2.7%) experienced treatment failure despite optimal therapy. Nine patients (8.1%) discontinued MVC owing to intolerance of their ART regimen. Severe laboratory abnormalities were deemed to be unrelated to MVC use. During the 487 person-years of follow-up, 18 patients (16.2%) died. MVC use in this heavily pre-treated cohort was generally well tolerated during long-term follow-up. Furthermore, use of MVC resulted in a good immunological and virological response in clinical practice.

A 30 kDa polyethylene glycol-enfuvirtide complex enhances the exposure of enfuvirtide in lymphatic viral reservoirs in rats.

HIV therapy with anti-retroviral drugs is limited by the poor exposure of viral reservoirs, such as lymphoid tissue, to these small molecule drugs. We therefore investigated the effect of PEGylation on the anti-retroviral activity and subcutaneous lymphatic pharmacokinetics of the peptide-based fusion inhibitor enfuvirtide in thoracic lymph duct cannulated rats. Both the peptide and the PEG were quantified in plasma and lymph via ELISA. Conjugation to a single 5 kDa linear PEG decreased anti-HIV activity three-fold compared to enfuvirtide. Whilst plasma and lymphatic exposure to peptide mass was moderately increased, the loss of anti-viral activity led to an overall decrease in exposure to enfuvirtide activity. A 20 kDa 4-arm branched PEG conjugated with an average of two enfuvirtide peptides decreased peptide activity by six-fold. Plasma and lymph exposure to enfuvirtide, however, increased significantly such that anti-viral activity was increased two- and six-fold respectively. The results suggest that a multi-enfuvirtide-PEG complex may optimally enhance the anti-retroviral activity of the peptide in plasma and lymph.

Towards a Maraviroc long-acting injectable nanoformulation.

Suboptimal adherence to antiretroviral (ARV) therapy can lead to insufficient drug exposure leading to viral rebound and increased likelihood of resistance. This has driven the development of long-acting injectable (LAI) formulations which may mitigate some of these problems. Maraviroc (MVC) is an orally dosed CCR5 antagonist approved for use in patients infected with CCR5-trophic HIV-1. MVC prevents viral entry into host cells, is readily distributed to biologically relevant tissues and has an alternative resistance profile compared to more commonly used therapies. This makes a MVC LAI formulation particularly appealing for implementation in Pre-Exposure Prophylaxis (PrEP). A 70 wt% MVC-loaded nanodispersion stabilised with polyvinyl alcohol (PVA) and sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate (AOT) was prepared using emulsion-templated freeze-drying. In vitro release rate studies revealed over a 22% decrease in MVC release rate constant across a size selective membrane compared with an aqueous solution of MVC (<5% DMSO). Pharmacokinetic studies in rats were subsequently carried out following intramuscular injection of either the nanodispersion or an aqueous MVC preparation (<5% DMSO). Results demonstrated over a 3.4-fold increase in AUC0-∞ (1959.71 vs 567.17 ng.h ml), over a 2.6-fold increase in MVCs terminal half-life (t½) (140.69 vs 53.23 h) and MVC concentrations present up to 10-days. These data support development of a MVC LAI formulation with potential application in HIV therapy or prevention.

Transdermal Delivery of Enfuvirtide in a Porcine Model Using a Low-Frequency, Low-Power Ultrasound Transducer Patch.

Ultrasound-mediated transdermal delivery is a promising parenteral administration method for large-molecule or unstable medications. This study evaluated skin health and systemic delivery when administering enfuvirtide, an injectable anti-retroviral medication, over a 1-mo period in a porcine model using a low-frequency cymbal transducer. Three groups received twice-daily treatments: (i) enfuvirtide injection control (n = 12); (ii) saline ultrasound control (n = 6); and (iii) enfuvirtide ultrasound treatment (n = 13). Ultrasound parameters were as follows: 30-min exposure, 90 mW/cm², 24-26 kHz and 15% duty cycle. No statistical difference in trans-epidermal water loss, a measure of skin health and function, was seen between ultrasound-treated and control skin sites for either saline (p = 0.50) or enfuvirtide (p = 0.29) groups. Average trough plasma concentrations of enfuvirtide were 0.6 ± 0.2 and 2.8 ± 0.8 µg/mL for ultrasound and injection, respectively. Tolerability and efficacy results indicate that chronic, low-frequency ultrasound exposure can be a practical means for transdermal delivery of medications such as enfuvirtide.

Nanobody-Fc constructs targeting chemokine receptor CXCR4 potently inhibit signaling and CXCR4-mediated HIV-entry and induce antibody effector functions.

Upregulation of the chemokine receptor CXCR4 contributes to the progression and metastasis of both solid and hematological malignancies, rendering this receptor an attractive therapeutic target. Besides the only FDA-approved CXCR4 antagonist Plerixafor (AMD3100), multiple other classes of CXCR4-targeting molecules are under (pre-)clinical development. Nanobodies (Nb), small single variable domains of heavy-chain only antibodies from Camelids, have appeared to be ideal antibody-fragments for targeting a broad range of epitopes and cavities within GPCRs such as CXCR4. Compared to conventional antibodies, monovalent nanobodies show fast blood clearance and no effector functions. In order to further increase their binding affinities and to restore antibody-mediated effector functions, we have constructed three different bivalent nanobody Fc-fusion molecules (Nb-Fc), targeting distinct epitopes on CXCR4, via fusion of Nbs to a Fc domain of a human IgG1 antibody. Most Nb-Fc constructs show increased binding affinity and enhanced potency in CXCL12 displacement, inhibition of CXCL12-induced signaling and CXCR4-mediated HIV entry, when compared to their monovalent Nb counterparts. Moreover, Nb-Fc induced ADCC- and CDC-mediated cell-death of CXCR4-overexpressing CCRF-CEM leukemia cells and did not affect cells expressing low levels or no CXCR4. These highly potent CXCR4 Nb-Fc constructs with Fc-mediated effector functions are attractive molecules to therapeutically target CXCR4-overexpressing tumors.

CXCR4-targeting nanobodies differentially inhibit CXCR4 function and HIV entry.

The chemokine receptor CXCR4 and its ligand CXCL12 contribute to a variety of human diseases, such as cancer. CXCR4 is also a major co-receptor facilitating HIV entry. Accordingly, CXCR4 is considered as an attractive therapeutic target. Drug side effects and poor pharmacokinetic properties have been major hurdles that have prevented the implementation of CXCR4-directed inhibitors in treatment regimes. We evaluated the activity of a new and promising class of biologics, namely CXCR4-targeting nanobodies, with the purpose of identifying nanobodies that would preferentially inhibit HIV infection, while minimally disturbing other CXCR4-related functions. All CXCR4-interacting nanobodies inhibited CXCL12 binding and receptor-mediated calcium mobilization with comparable relative potencies. Importantly, the anti-HIV-1 activity of the nanobodies did not always correlate with their ability to modulate CXCR4 signaling and function, indicating that the anti-HIV and anti-CXCR4 activity are not entirely overlapping and may be functionally separated. Three nanobodies with divergent activity profiles (VUN400, VUN401 and VUN402) were selected for in depth biological evaluation. While all three nanobodies demonstrated inhibitory activity against a wide range of HIV (X4) strains, VUN402 poorly blocked CXCL12-induced CXCR4 internalization, chemotaxis and changes in cell morphology. Each of these nanobodies recognized distinct, although partially overlapping epitopes on CXCR4, which might underlie their distinct activity profiles. Our results demonstrate the potential of CXCR4-targeting nanobody VUN402 as a novel lead and starting point for the development of a more potent and selective anti-HIV agent.

A novel multivalent DNA helix-based inhibitor showed enhanced anti-HIV-1 fusion activity.

DNA helix-based HIV-1 fusion inhibitors have been discovered as potent drug candidates, but further research is required to enhance their efficiency. The trimeric structure of the HIV-1 envelope glycoprotein provides a structural basis for multivalent drug design. In this work, a "multi-domain" strategy was adopted for design of an oligodeoxynucleotide with assembly, linkage, and activity domains. Built on the self-assembly of higher-order nucleic acid structure, a novel category of multivalent DNA helix-based HIV-1 fusion inhibitor could be easily obtained by a simple annealing course in solution buffer, with no other chemical synthesis for multivalent connection. An optimized multivalent molecule, M4, showed significantly higher anti-HIV-1 fusion activity than did corresponding monovalent inhibitors. Examination of the underlying mechanism indicated that M4 could interact with HIV-1 glycoproteins gp120 and gp41, thereby inhibiting 6HB formation in the fusion course. M4 also showed anti-RDDP and anti-RNase H activity of reverse transcriptase. Besides, these assembled molecules showed improved in vitro metabolic stability in liver homogenate, kidney homogenate, and rat plasma. Moreover, little acute toxicity was observed. Our findings aid in the structural design and understanding of the mechanisms of DNA helix-based HIV-1 inhibitors. This study also provides a general strategy based on a new structural paradigm for the design of other multivalent nucleic acid drugs.

A Small-Molecule CD4-Mimetic Compound Protects Bone Marrow-Liver-Thymus Humanized Mice From HIV-1 Infection.

Background: Small-molecule CD4-mimetic compounds (CD4mc) inhibit human immunodeficiency virus (HIV-1) entry by blocking binding to the CD4 receptor and by premature triggering of the viral envelope glycoprotein (Env) spike. Methods: The efficacy of a CD4mc in protecting bone marrow-liver-thymus (BLT) humanized mice from vaginal HIV-1 challenge was evaluated. Results: Intravaginal application of the CD4mc JP-III-48, either before or simultaneously with virus challenge, protected BLT humanized mice from HIV-1JR-CSF infection in a dose- dependent manner. Conclusion: The direct antiviral effects of a CD4mc prevent HIV-1 infection in a murine model of sexual transmission.

PRO 140, a monoclonal antibody targeting CCR5, as a long-acting, single-agent maintenance therapy for HIV-1 infection.

Background PRO 140 is a humanized monoclonal antibody targeting CCR5 with potent antiviral activity in patients with CCR5-tropic HIV-1 infection. In phase 2b studies, we evaluated the long-term efficacy, safety, and tolerability of PRO 140 monotherapy in maintaining viral suppression for over 24 months in patients who were stable on combination antiretroviral therapy on entry into the trials. Methods and Results Forty-one adult patients, infected exclusively with CCR5-tropic HIV-1 with viral loads <50 copies/mL, were switched from daily oral combination ART regimens to weekly PRO 140 monotherapy for 12 weeks. Participants who completed 12 weeks of treatment without experiencing virologic rebound were allowed to self-administer PRO 140 as a 350 mg subcutaneous injection weekly, for up to an additional 160 weeks. Participants were monitored bi-weekly for one year, and every four weeks thereafter for virologic rebound. PRO 140 provided virologic suppression in 23/41 (56.1%) participants for 12 weeks and was well tolerated. Ten (10) participants are currently ongoing, of which nine participants have completed more than two years of monotherapy treatment (47-129 weeks). Participants experiencing virologic rebound achieved full viral suppression upon re-initiation of oral combination ART regimen. Anti-PRO 140 antibodies were not detected in any patient, and no drug-related major adverse events or treatment discontinuations were reported. Conclusions PRO 140 has a potential to address an unmet need for a long-acting, single-agent, maintenance regimen for HIV infection in selected patients. Studies are underway to determine host and/or virologic factors that may predict treatment success on PRO 140 monotherapy. Moreover, it has sufficient potency for a prolonged period of monotherapy that it would be an excellent component of a multi long-acting drug combination.

A CCR5 antagonist-based HIV entry inhibitor exhibited potent spermicidal activity: Potential application for contraception and prevention of HIV sexual transmission.

B07 is a small-molecule CCR5 antagonist-based HIV-1 entry inhibitor that is being developed as an anti-HIV microbicide for preventing sexual transmission of HIV. Here we evaluated its spermicidal and contraceptive potential, including sperm motility, plasma membrane integrity, and contraceptive efficacy tested in rabbits. We found that B07 inhibited sperm motility and movement patterns in a concentration- and time-dependent manner. Within 30 min, B07 induced sperm immobilization with the minimum 100% effective concentration and median effective concentration of 640.0 and 64.4 µg/mL, respectively. The hypo-osmotic swelling test showed that plasma membranes of B07-treated sperms exhibited slight disruption, as verified by electron micrographs. In both B07 gel and N-9 gel groups, not a single implantation site or embryo was observed based on the contraceptive efficacy test in rabbits, indicating that B07 could effectively block the potential of sperm to reach and/or fertilize oocytes. The safety profile of B07 in vivo was evaluated by use of an optimized rabbit vaginal irritation test. While the pathological scores of the N-9 gel group was 14.67 ±â€¯1.21, those of the blank control and B07 gel groups were 2.17 ±â€¯0.76 and 4.00 ±â€¯0.89, respectively, which were within the clinically acceptable range (<8). The proportion of inflammatory cells and CD45+ cells in the cervicovaginal lavages of the B07 gel group showed no significant change compared to those of the control group. Therefore, our results confirmed that B07 exhibited significant spermicidal and contraceptive effects, suggesting its potential for development as a microbicidal spermicide for contraception and prevention of HIV sexual transmission.

Pharmacokinetic and Chemical Synthesis Optimization of a Potent d-Peptide HIV Entry Inhibitor Suitable for Extended-Release Delivery.

Peptides often suffer from short in vivo half-lives due to proteolysis and renal clearance that limit their therapeutic potential in many indications, necessitating pharmacokinetic (PK) enhancement. d-Peptides, composed of mirror-image d-amino acids, overcome proteolytic degradation but are still vulnerable to renal filtration due to their small size. If renal filtration could be slowed, d-peptides would be promising therapeutic agents for infrequent dosing, such as in extended-release depots. Here, we tether a diverse set of PK-enhancing cargoes to our potent, protease-resistant d-peptide HIV entry inhibitor, PIE12-trimer. This inhibitor panel provides an opportunity to evaluate the PK impact of the cargoes independently of proteolysis. While all the PK-enhancing strategies (PEGylation, acylation, alkylation, and cholesterol conjugation) improved in vivo half-life, cholesterol conjugation of PIE12-trimer dramatically improves both antiviral potency and half-life in rats, making it our lead anti-HIV drug candidate. We designed its chemical synthesis for large-scale production (CPT31) and demonstrated that the PK profile in cynomolgous monkeys supports future development of monthly or less frequent depot dosing in humans. CPT31 could address an urgent need in both HIV prevention and treatment.

Screening and Functional Profiling of Small-Molecule HIV-1 Entry and Fusion Inhibitors.

HIV-1 entry and fusion with target cells is an important target for antiviral therapy. However, a few currently approved treatments are not effective as monotherapy due to the emergence of drug resistance. This consideration has fueled efforts to develop new bioavailable inhibitors targeting different steps of the HIV-1 entry process. Here, a high-throughput screen was performed of a large library of 100,000 small molecules for HIV-1 entry/fusion inhibitors, using a direct virus-cell fusion assay in a 384 half-well format. Positive hits were validated using a panel of functional assays, including HIV-1 specificity, cytotoxicity, and single-cycle infectivity assays. One compound-4-(2,5-dimethyl-pyrrol-1-yl)-2-hydroxy-benzoic acid (DPHB)-that selectively inhibited HIV-1 fusion was further characterized. Functional experiments revealed that DPHB caused irreversible inactivation of HIV-1 Env on cell-free virions and that this effect was related to binding to the third variable loop (V3) of the gp120 subunit of HIV-1 Env. Moreover, DPHB selectively inhibited HIV-1 strains that use CXCR4 or both CXCR4 and CCR5 co-receptors for entry, but not strains exclusively using CCR5. This selectivity was mapped to the gp120 V3 loop using chimeric Env glycoproteins. However, it was found that pure DPHB was not active against HIV-1 and that its degradation products (most likely polyanions) were responsible for inhibition of viral fusion. These findings highlight the importance of post-screening validation of positive hits and are in line with previous reports of the broad antiviral activity of polyanions.

Developing a Bayesian adaptive design for a phase I clinical trial: a case study for a novel HIV treatment.

The design of phase I studies is often challenging, because of limited evidence to inform study protocols. Adaptive designs are now well established in cancer but much less so in other clinical areas. A phase I study to assess the safety, pharmacokinetic profile and antiretroviral efficacy of C34-PEG4 -Chol, a novel peptide fusion inhibitor for the treatment of HIV infection, has been set up with Medical Research Council funding. During the study workup, Bayesian adaptive designs based on the continual reassessment method were compared with a more standard rule-based design, with the aim of choosing a design that would maximise the scientific information gained from the study. The process of specifying and evaluating the design options was time consuming and required the active involvement of all members of the trial's protocol development team. However, the effort was worthwhile as the originally proposed rule-based design has been replaced by a more efficient Bayesian adaptive design. While the outcome to be modelled, design details and evaluation criteria are trial specific, the principles behind their selection are general. This case study illustrates the steps required to establish a design in a novel context. Copyright © 2016 John Wiley & Sons, Ltd.

Brief Report: Pharmacokinetic/Pharmacodynamic Investigation of Single-Dose Oral Maraviroc in the Context of HIV-1 Pre-exposure Prophylaxis.

To investigate the pharmacokinetics/pharmacodynamics of single-dose maraviroc 300 mg in HIV-1 exposure compartments. Maraviroc concentrations in blood, secretions (vaginal, urethral, oral, and rectal), and tissue (vaginal and rectal) were measured, and ex vivo challenge was performed in 54 healthy volunteers to study protection from HIV infection. Maraviroc Cmax occurred within 4 hours in most compartments. Concentrations from 4 to 72 hours were above intracellular (IC) IC90 in all compartments, range 15-8095 ng/mL. Mean AUC0-72 compartment-to-plasma ratios were highest in the rectum (45-819) and urethra (144) compared with the female genital tract (1.6-4.8) and saliva (0.2). No sex differences in AUC0-72 or Cmax were observed. No ex vivo protection from HIV-1BaL occurred in rectal or vaginal tissue. Despite high and sustained concentrations, single-dose maraviroc was not protective against ex vivo challenge of vaginal/rectal tissue.