Weekly Oral Tenofovir Alafenamide Protects Macaques from Vaginal and Rectal Simian HIV Infection

Pre-exposure prophylaxis (PrEP) with a weekly oral regimen of antiretroviral drugs could be a suitable preventative option for individuals who struggle with daily PrEP or prefer not to use long-acting injectables. We assessed in macaques the efficacy of weekly oral tenofovir alafenamide (TAF) at doses of 13.7 or 27.4 mg/kg. Macaques received weekly oral TAF for six weeks and were exposed twice-weekly to SHIV vaginally or rectally on day 3 and 6 after each dose. Median TFV-DP levels in PBMCs following the 13.7 mg/kg dose were 3110 and 1137 fmols/106 cells on day 3 and 6, respectively. With the 27.4 mg/kg dose, TFV-DP levels were increased (~2-fold) on day 3 and 6 (6095 and 3290 fmols/106 cells, respectively). Both TAF doses (13.7 and 27.4 mg/kg) conferred high efficacy (94.1% and 93.9%, respectively) against vaginal SHIV infection. Efficacy of the 27.4 mg/kg dose against rectal SHIV infection was 80.7%. We estimate that macaque doses of 13.7 and 27.4 mg/kg are equivalent to approximately 230 and 450 mg of TAF in humans, respectively. Our findings demonstrate the effectiveness of a weekly oral PrEP regimen and suggest that a clinically achievable oral TAF dose could be a promising option for non-daily PrEP.

Pharmacokinetics of single dose doxycycline in the rectum, vagina, and urethra: implications for prevention of bacterial sexually transmitted infections

BACKGROUND

Clinical trials showed a single oral dose of doxycycline taken after sex protects against STIs among men who have sex with men (MSM) but not women. Pharmacokinetic data at vaginal, rectal and penile sites of STI exposure are lacking. We examined vaginal, rectal and urethral doxycycline concentrations in men and women to better inform STI prevention.

METHODS

Doxycycline pharmacokinetics in male and female participants 18-59 years of age were evaluated in blood and urine and on rectal and vaginal swabs collected at 1, 2, 4, 8, 24, 48, 72, 96 and 168 h after receiving a 200 mg oral doxycycline dose in a non-randomised single dose open label single centre study in Atlanta, Georgia. Rectal, vaginal, and cervical biopsies and male urethral swabs were collected 24 h after dosing (Trial registration: NCT04860505). Doxycycline was measured by liquid chromatography-mass spectrometry.

FINDINGS

Eleven male and nine female participants participated in the study. Doxycycline concentrations on rectal and vaginal swabs collected up to 96 h after dosing were approximately twice those of plasma and remained above minimum inhibitory concentrations (MICs) for at least four, three, and two days for Chlamydia trachomatis, Treponema pallidum, and tetracycline-sensitive Neisseria gonorrhoeae, respectively. Geometric mean doxycycline concentrations in male urethral secretions (1.166 μg/mL; 95% CI 0.568-2.394 μg/mL), male rectal (0.596 μg/g; 0.442-0.803 μg/g), vaginal (0.261 μg/g; 0.098-0.696 μg/g) and cervical tissue (0.410 μg/g; 0.193-0.870 μg/g) in biopsies collected 24 h after dosing exceeded MICs. Plasma and urine doxycycline levels defined adherence markers up to four and seven days postdosing, respectively. No adverse events were reported in this study.

INTERPRETATION

Doxycycline efficiently distributes to the rectum, vagina and urethra. Findings can help explain efficacy of STI prevention by doxycycline.

FUNDING

Funded by CDC intramural funds, CDC contract HCVJCG-2020-45044 (to CFK).

The menstrual cycle regulates migratory CD4 T-cell surveillance in the female reproductive tract via CCR5 signaling

Despite their importance for immunity against sexually transmitted infections, the composition of female reproductive tract (FRT) memory T-cell populations in response to changes within the local tissue environment under the regulation of the menstrual cycle remains poorly defined. Here, we show that in humans and pig-tailed macaques, the cycle determines distinct clusters of differentiation 4 T-cell surveillance behaviors by subsets corresponding to migratory memory (TMM) and resident memory T cells. TMM displays tissue-itinerant trafficking characteristics, restricted distribution within the FRT microenvironment, and distinct effector responses to infection. Gene pathway analysis by RNA sequencing identified TMM-specific enrichment of genes involved in hormonal regulation and inflammatory responses. FRT T-cell subset fluctuations were discovered that synchronized to cycle-driven CCR5 signaling. Notably, oral administration of a CCR5 antagonist drug blocked TMM trafficking. Taken together, this study provides novel insights into the dynamic nature of FRT memory CD4 T cells and identifies the menstrual cycle as a key regulator of immune surveillance at the site of STI pathogen exposure.

Extended post-exposure protection against vaginal SHIV infection with tenofovir alafenamide fumarate/elvitegravir inserts in macaques

Vaginal inserts that can be used on demand before or after sex may be a desirable HIV prevention option for women. We recently showed that inserts containing tenofovir alafenamide fumarate (TAF/20mg) and elvitegravir (EVG/16mg) were highly protective against repeated SHIV vaginal exposures when administered to macaques 4h before or after virus exposure (93% and 100%, respectively). Here, we show in the same macaque model that insert application 8h or 24h after exposure maintains high efficacy (94.4% and 77.2%, respectively). These data extend the protective window by TAF/EVG inserts and inform their clinical development for on-demand prophylaxis in women.

Risk factors for nosocomial COVID-19 in a French university hospital

OBJECTIVES

Prevention strategies implemented by hospitals to reduce nosocomial transmission of SARS-CoV-2 sometimes failed. Our aim was to determine the risk factors for nosocomial COVID-19.

PATIENTS AND METHODS

A case-control study was conducted (September 1, 2020-January 31, 2021) with adult patients hospitalized in medical or surgical units. Infants or patients hospitalized in ICU were excluded. Cases were patients with nosocomial COVID-19 (clinical symptoms and RT-PCR+ for SARS-CoV-2 or RT-PCR+ for SARS-CoV-2 with Ct ≤28 more than 5days after admission); controls were patients without infection (RT-PCR- for SARS-CoV-2 >5 days after admission). They were matched according to length of stay before diagnosis and period of admission. Analyses were performed with a conditional logistic regression.

RESULTS

A total of 281 cases and 441 controls were included. In the bivariate analysis, cases were older (OR per 10years: 1.22; 95%CI [1.10;1.36]), had more often shared a room (OR: 1.74; 95%CI [1.25;2.43]) or a risk factor for severe COVID-19 (OR: 1.94; 95%CI [1.09;3.45]), were more often hospitalized in medical units [OR: 1.59; 95%CI [1.12;2.25]), had higher exposure to contagious health care workers (HCW; OR per 1person-day: 1.12; 95%CI [1.08;1.17]) and patients (OR per 1 person-day: 1.11; 95%CI [1.08;1.14]) than controls. In an adjusted model, risk factors for nosocomial COVID-19 were exposure to contagious HCW (aOR per 1person-day: 1.08; 95%CI [1.03;1.14]) and to contagious patients (aOR per 1person-day: 1.10; 95%CI [1.07;1.13]).

CONCLUSIONS

Exposure to contagious professionals and patients are the main risk factors for nosocomial COVID-19.

Ultra-long-acting in-situ forming implants with cabotegravir protect female macaques against rectal SHIV infection

Ultra-long-acting delivery platforms for HIV pre-exposure prophylaxis (PrEP) may increase adherence and maximize public health benefit. We report on an injectable, biodegradable, and removable in-situ forming implant (ISFI) that is administered subcutaneously and can release the integrase inhibitor cabotegravir (CAB) above protective benchmarks for more than 6 months. CAB ISFIs are well-tolerated in female mice and female macaques showing no signs of toxicity or chronic inflammation. In macaques, median plasma CAB concentrations exceed established PrEP protection benchmarks within 3 weeks and confer complete protection against repeated rectal SHIV challenges. Implant removal via a small incision in 2 macaques at week 12 results in a 7- to 48-fold decrease in plasma CAB levels within 72 hours. Modeling to translate CAB ISFI dosing suggests that a 3 mL injection would exceed protective benchmarks in humans for over 5 months post administration. Our results support the clinical advancement of CAB ISFIs for ultra-long-acting PrEP in humans.

Pharmacology of boosted and unboosted integrase strand transfer inhibitors for two-dose event-driven HIV prevention regimens among men

BACKGROUND

Event-driven HIV prevention strategies are a priority for users who do not require daily pre-exposure prophylaxis (PrEP). Regimens containing integrase strand transfer inhibitors (INSTIs) are under evaluation as alternatives to daily PrEP. To better understand INSTI distribution and inform dosing selection we compared the pharmacology of two-dose boosted elvitegravir and unboosted bictegravir regimens in MSM.

MATERIALS AND METHODS

Blood, rectal and penile secretions and rectal biopsies were collected from 63 HIV-negative MSM aged 18-49 years. Specimens were collected up to 96 h after two oral doses of tenofovir alafenamide and emtricitabine with elvitegravir boosted by cobicistat or unboosted bictegravir given 24 h apart. Antiretroviral drugs were measured by LC-MS.

RESULTS

Mean bictegravir plasma concentrations remained above the 95% protein-adjusted effective concentration 96 h after dosing [273 (95% CI: 164-456) ng/mL] whereas elvitegravir plasma concentrations became undetectable 48 h after the second dose. Bictegravir and elvitegravir reached rectal tissues within 2 h after the first dose, and elvitegravir tissue concentrations [1.07 (0.38-13.51) ng/mg] were greater than bictegravir concentrations [0.27 (0.15-0.70) ng/mg]. Both INSTIs became undetectable in tissues within 96 h. Elvitegravir and bictegravir were not consistently detected in penile secretions.

CONCLUSIONS

Whereas bictegravir plasma concentrations persist at least 4 days after a two-oral-dose HIV prophylaxis regimen, elvitegravir accumulates in mucosal tissues. Differing elvitegravir and bictegravir distribution may result in variable mucosal and systemic antiviral activity and can inform dosing strategies for event-driven HIV prevention.

Single dose topical inserts containing tenofovir alafenamide fumarate and elvitegravir provide pre- and post-exposure protection against vaginal SHIV infection in macaques

BACKGROUND

Vaginal products for HIV prevention that can be used on-demand before or after sex may be a preferable option for women with low frequency or unplanned sexual activity or who prefer not to use daily or long-acting pre-exposure prophylaxis (PrEP). We performed dose ranging pharmacokinetics (PK) and efficacy studies of a vaginally applied insert containing tenofovir alafenamide fumarate (TAF) and elvitegravir (EVG) in macaques under PrEP or post-exposure prophylaxis (PEP) modalities.

METHODS

PK studies were performed in 3 groups of pigtailed macaques receiving inserts with different fixed-dose combinations of TAF and EVG (10/8, 20/16 and 40/24 mg). PrEP and PEP efficacy of a selected insert was investigated in a repeat exposure vaginal SHIV transmission model. Inserts were administered 4 h before (n = 6) or after (n = 6) repeated weekly SHIV exposures. Infection outcome was compared with macaques receiving placebo inserts (n = 12).

FINDINGS

Dose ranging studies showed rapid and sustained high drug concentrations in vaginal fluids and tissues across insert formulations with minimal dose proportionality. TAF/EVG (20/16 mg) inserts were selected for efficacy evaluation. Five of the 6 animals receiving these inserts 4 h before and 6/6 animals receiving inserts 4 h after SHIV exposure were protected after 13 challenges (p = 0.0088 and 0.0077 compared to placebo, respectively). The calculated PrEP and PEP efficacy was 91.0% (95% CI = 32.2%-98.8%) and 100% (95% CI = undefined), respectively.

INTERPRETATION

Inserts containing TAF/EVG provided high protection against vaginal SHIV infection when administered within a 4 h window before or after SHIV exposure. Our results support the clinical development of TAF/EVG inserts for on-demand PrEP and PEP in women.

FUNDING

Funded by CDC intramural funds, an interagency agreement between CDC and USAID (USAID/CDC IAA AID-GH-T-15-00002), and by the U.S. President's Emergency Plan for AIDS Relief (PEPFAR) through the U.S. Agency for International Development (USAID) under a Cooperative Agreement (AID-OAA-A-14-00010) with CONRAD/Eastern Virginia Medical School.

Sexually transmitted infections and depot medroxyprogesterone acetate do not impact protection from simian HIV acquisition by long-acting cabotegravir in macaques

OBJECTIVE

We had previously shown that long-acting cabotegravir (CAB-LA) injections fully protected macaques from vaginal simian HIV (SHIV) infection. Here, we reassessed CAB-LA efficacy in the presence of depot medroxyprogesterone acetate and multiple sexually transmitted infections (STIs) that are known to increase HIV susceptibility in women.

DESIGN

Two macaque models of increasing vaginal STI severity were used for efficacy assessment.

METHODS

The first study (n = 11) used a double STI model that had repeated exposures to two vaginal STI, Chlamydia trachomatis and Trichomonas vaginalis. Six animals were CAB-LA treated and five were controls. The second study (n = 9) included a triple STI model with repeated exposures to C. trachomatis, T. vaginalis and syphilis, and the contraceptive, depot medroxyprogesterone acetate (DMPA). Six animals were CAB-LA treated and three were controls. All animals received up to 14 vaginal SHIV challenges. A survival analysis was performed to compare the number of SHIV challenges to infection in the drug-treated group compared with untreated controls over time.

RESULTS

All six CAB-LA treated animals in both models, the double STI or the triple STI-DMPA model, remained protected after 14 SHIV vaginal challenges, while the untreated animals became SHIV-infected after a median of two challenges (log-rank P < 0.001) or one challenge (log-rank P = 0.002), respectively. Both models recapitulated human STI disease, with vaginal discharge, ulcers, and seroconversion.

CONCLUSION

In these high and sustained susceptibility models spanning more than 3 months, CAB-LA maintained complete efficacy, demonstrating robustness of the CAB-LA dose used in clinical trials, and suggesting its insensitivity to multiple STIs and DMPA.

Pharmacokinetics of vaginally applied integrase inhibitors in macaques

OBJECTIVES

We conducted a detailed pharmacokinetic assessment in macaques treated with vaginal gels formulated with HIV integrase strand transfer inhibitors (INSTIs) to better understand drug distribution and identify INSTI concentrations associated with previously demonstrated in vivo protection against vaginal simian HIV challenge.

METHODS

Six macaques received vaginal gel containing 1% raltegravir (30 mg) once-weekly over 6 weeks. Following a washout period, five macaques received once-weekly gel containing 0.23% L-870,812 (7 mg). Drug concentrations were measured in plasma, mucosal fluids and vaginal tissues at baseline and 2, 5 and 24 h post-dosing.

RESULTS

The median maximum concentration (Cmax) for raltegravir and L-870,812 in plasma was below the limit of quantification and 41.1 ng/mL, respectively. The Cmax in vaginal fluids (1441 and 1250 μg/mL) and tissues (266.7 and 368.4 μg/g) was achieved 2-5 h after dosing, respectively. A similar half-life was observed for raltegravir and L-870,812 in vaginal fluids (8-10 h) and remained 3-4 orders of magnitude above the protein-adjusted IC95 (0.016 and 0.106 μg/mL, respectively) at 24 h. Drug concentrations in vaginal fluids correlated well with those in vaginal tissues (Pearson r ≥ 0.788). Both drugs were consistently detected in rectal fluids 2 h after vaginal dosing, albeit at much lower levels (31-92-fold) than those in vaginal fluids.

CONCLUSIONS

To the best of our knowledge, this study provides the first data on INSTI levels in vaginal tissues associated with in vivo protection and demonstrates rectal drug distribution of INSTIs after vaginal dosing. These findings may inform dose selection for topical products with INSTIs for HIV prevention.

Short Communication: Evaluation of Antiretroviral Drug Concentrations in Minimally Invasive Specimens for Potential Development of Point-of-Care Drug Assays

Point-of-care (POC) tests for antiretroviral drugs (ARVs) could help improve individual adherence. This study sought to define the utility of urine, blood, and buccal swabs as minimally invasive specimens amenable to development of POC tests for ARVs. Urine, dried blood spots (DBS) and buccal swabs were collected from 35 HIV-negative men between 2 and 96 h after a single dose of tenofovir (TFV) alafenamide/emtricitabine (FTC)/elvitegravir (EVG)/cobicistat and darunavir (DRV). ARV concentrations were measured by high-performance liquid chromatography-mass spectrometry. High concentrations of FTC, DRV, and TFV were detectable in urine at least 24 h after dosing. FTC, DRV, and EVG remained detectable in DBS at least 24 h postdose. FTC and DRV were detectable on buccal swabs up to 2 and 24 h postdose, respectively. TFV was not detectable in DBS or buccal swabs collected between 2 and 96 h after dosing. Variable distribution of ARVs in minimally invasive specimens highlights the challenge of developing POC assays for recent ARV exposure.

Development, Characterization and In Vivo Pharmacokinetic Assessment of Rectal Suppositories Containing Combination Antiretroviral Drugs for HIV Prevention

Receptive anal intercourse (RAI) contributes significantly to HIV acquisition underscoring the need to develop HIV prevention options for populations engaging in RAI practices. We explored the feasibility of formulating rectal suppositories with potent antiviral drugs for on-demand use. A fixed-dose combination of tenofovir (TFV) and elvitegravir (EVG) (40 mg each) was co-formulated in six different suppository bases (three fat- and three water-soluble). Fat-soluble witepsol H15 and water-soluble polyethylene glycol (PEG) based suppositories demonstrated favorable in vitro release and were advanced to assess in vivo pharmacokinetics following rectal administration in macaques. In vivo drug release profiles were similar for both suppository bases. Median concentrations of TFV and EVG detected in rectal fluids at 2 h were 1- and 2-logs higher than the in vitro IC50, respectively; TFV-diphosphate levels in rectal tissues met or exceeded those associated with high efficacy against rectal simian HIV (SHIV) exposure in macaques. Leveraging on these findings, a PEG-based suppository with a lower dose combination of tenofovir alafenamide (TAF) and EVG (8 mg each) was developed and found to achieve similar rectal drug exposures in macaques. This study establishes the utility of rectal suppositories as a promising on-demand strategy for HIV PrEP and supports their clinical development.

Antiretroviral drug exposure in urethral and glans surface sampling of the penis

BACKGROUND

HIV exposure to penile tissues provides a risk of acquisition among men, yet studies evaluating penile antiretroviral (ARV) drug distribution have been lacking. We measured ARVs on urethral and glans surface swabs collected following a dose of tenofovir alafenamide, emtricitabine, elvitegravir, darunavir and cobicistat.

METHODS

Thirty-five HIV-negative male participants provided urethral swabs, glans swabs, rectal swabs, blood and urine up to 96 h following a single dose of tenofovir alafenamide/emtricitabine/elvitegravir/cobicistat and darunavir. ARVs were measured by liquid chromatography-mass spectrometry with a lower limit of detection (LOD) of 1 ng/swab for swabs and 10 ng/mL for plasma and urine. Concentrations are reported as median and range.

RESULTS

Urethral swab emtricitabine and darunavir concentrations peaked at 4 h for emtricitabine (36 ng/swab; 3-307 ng/swab) and 8 h for darunavir (25 ng/swab; 2-52 ng/swab). Glans swab emtricitabine and darunavir concentrations peaked 24 h after dosing (emtricitabine 14 ng/swab, <LOD-328 ng/swab; darunavir 6 ng/swab, <LOD-149 ng/swab). Estimated peak urethral secretion emtricitabine and darunavir concentrations are between 10 and 20 μg/mL, similar to rectal secretions, 4-fold greater than in plasma, but 2-fold lower than in urine. Tenofovir and elvitegravir were detected on less than 20% of urethral or glans swabs collected within 24 h of dosing.

CONCLUSIONS

We document ARV dosing in the urethra and on the glans surface with high drug concentrations noted for emtricitabine and darunavir and lower tenofovir and elvitegravir concentrations. Data suggest a potential protective role of urethral emtricitabine or darunavir against penile HIV acquisition.

The effect of depot medroxyprogesterone acetate on tenofovir alafenamide in rhesus macaques

Prevention of HIV infection and unintended pregnancies are public health priorities. In sub-Saharan Africa, where HIV prevalence is highest, depot medroxyprogesterone acetate (DMPA) is widely used as contraception. Therefore, understanding potential interactions between DMPA and antiretrovirals is critical. Here, we use a macaque model to investigate the effect of DMPA on the pharmacology of the antiretroviral tenofovir alafenamide (TAF). Female rhesus macaques received 30 mg of DMPA (n = 9) or were untreated (n = 9). Macaques received a human equivalent dose of TAF (1.5 mg/kg) orally by gavage. Tenofovir (TFV) and TFV-diphosphate (TFV-DP) were measured in blood, secretions, and tissues over 72 h. The median area under the curve (AUC_0-72h) values for TFV-DP in peripheral blood mononuclear cells were similar in DMPA-treated (6991 fmol*h/10⁶ cells) and untreated controls (5256 fmol*h/10⁶ cells) (P = 0.174). Rectal tissue TFV-DP concentrations from DMPA+ animals [median: 20.23 fmol/mg of tissue (range: 4.94-107.95)] were higher than the DMPA- group [median: below the limit of quantification (BLOQ-11.92)], (P = 0.019). TFV-DP was not detectable in vaginal tissue from either group. A high-dose DMPA treatment in macaques was associated with increased rectal TFV-DP levels, indicating a potential tissue-specific drug-drug interaction. The lack of detectable TFV-DP in the vaginal tissue warrants further investigation of PrEP efficacy with single-agent TAF products. DMPA did not affect systemic TAF metabolism, with similar PBMC TFV-DP in both groups, suggesting that DMPA use should not alter the antiviral activity of TAF.

Single oral dose for HIV pre or post-exposure prophylaxis: user desirability and biological efficacy in macaques

BACKGROUND

Daily oral pre- or post-exposure prophylaxis (PrEP or PEP) is highly effective in preventing HIV infection. However, many people find it challenging to adhere to a daily oral regimen. Chemoprophylaxis with single oral doses of antiretroviral drugs taken before or after sex may better adapt to changing or unanticipated sexual practices and be a desirable alternative to daily PrEP or PEP. We investigated willingness to use a single oral pill before or after sex among men who have sex with men (MSM) and assessed the biological efficacy of a potent antiretroviral combination containing elvitegravir (EVG), emtricitabine (FTC), and tenofovir alafenamide (TAF).

METHODS

Data on willingness to use single-dose PrEP or PEP were obtained from the 2017 cycle of the American Men's Internet Survey (AMIS), an annual online behavioral surveillance survey of MSM in the United States. Antiretroviral drug levels were measured in humans and macaques to define drug distribution in rectal tissue and identify clinically relevant doses for macaque modeling studies. The biological efficacy of a single dose of FTC/TAF/EVG as PrEP or PEP was investigated using a repeat-challenge macaque model of rectal HIV infection.

FINDINGS

Through pharmacokinetic assessment in humans and macaques we found that EVG penetrates and concentrates in rectal tissues supporting its addition to FTC/TAF to boost and extend chemoprophylactic activity. Efficacy estimates for a single oral dose given to macaques 4h before or 2h after SHIV exposure was 91•7%[35•7%-98•9%] and 100%, respectively, compared to 80•1%[13•9%-95•4%] and 64•6%[-19•4%-89•5%] when single doses were given 6 and 24h post challenge, respectively. A two-dose regimen at 24h and 48h after exposure was also protective [77•1%[1•7%-94•7%].

INTERPRETATION

Informed by user willingness, human and macaque pharmacokinetic data, and preclinical efficacy we show that single-dose prophylaxis before or after sex is a promising HIV prevention strategy. Carefully designed clinical trials are needed to determine if any of these strategies will be effective in humans.

FUNDING

Funded by CDC intramural funds, CDC contract HCVJCG2-2016-03948 (to CFK), and a grant from the MAC AIDS Fund and by the National Institutes of Health [P30AI050409] - the Emory Center for AIDS Research (to MZ and TS).

Efficacy of Oral Tenofovir Alafenamide/Emtricitabine Combination or Single-Agent Tenofovir Alafenamide Against Vaginal Simian Human Immunodeficiency Virus Infection in Macaques

BACKGROUND

Tenofovir alafenamide (TAF)-based regimens are being evaluated for pre-exposure prophylaxis (PrEP). We used a macaque model of repeated exposures to simian human immunodeficiency virus (SHIV) to investigate whether TAF alone or the combination of TAF and emtricitabine (FTC) can prevent vaginal infection.

METHODS

Pigtail macaques were exposed vaginally to SHIV162p3 once a week for up to 15 weeks. Animals received clinical doses of FTC/TAF (n = 6) or TAF (n = 9) orally 24 hours before and 2 hours after each weekly virus exposure. Infection was compared with 21 untreated controls.

RESULTS

Five of the 6 animals in the FTC/TAF and 4 of the 9 animals in the TAF alone group were protected against infection (P = .001 and P = .049, respectively). The calculated efficacy of FTC/TAF and TAF was 91% (95% confidence interval [CI], 34.9%-98.8%) and 57.8% (95% CI, -8.7% to 83.6%), respectively. Infection in FTC/TAF but not TAF-treated macaques was delayed relative to controls (P = .005 and P = .114). Median tenofovir diphosphate (TFV-DP) levels in peripheral blood mononuclear cells (PBMCs) were similar among infected and uninfected macaques receiving TAF PrEP (351 and 143 fmols/106 cells, respectively; P = .921).

CONCLUSIONS

Emtricitabine/TAF provided a level of protection against vaginal challenge similar to FTC/TFV disoproxil fumarate combination in the macaque model. Our results support the clinical evaluation of FTC/TAF for PrEP in women.

Long-Acting Cabotegravir Protects Macaques Against Repeated Penile Simian-Human Immunodeficiency Virus Exposures

We used a novel penile simian-human immunodeficiency virus (SHIV) transmission model to investigate whether long-acting cabotegravir (CAB LA) prevents penile SHIV acquisition in macaques. Twenty-two macaques were exposed to SHIV via the foreskin and urethra once weekly for 12 weeks. Of these, 6 received human-equivalent doses of CAB LA, 6 received oral emtricitabine/tenofovir disoproxil fumarate, and 10 were untreated. The efficacy of CAB LA was high (94.4%; 95% confidence interval, 58.2%–99.3%) and similar to that seen with oral emtricitabine/tenofovir disoproxil fumarate (94.0%; 55.1%–99.2%). The high efficacy of CAB LA in the penile transmission model supports extending the clinical advancement of CAB LA preexposure prophylaxis to heterosexual men.

Training rhesus macaques to take daily oral antiretroviral therapy for preclinical evaluation of HIV prevention and treatment strategies

Background

Macaque models of simian or simian/human immunodeficiency virus (SIV or SHIV) infection are critical for the evaluation of antiretroviral (ARV)-based HIV treatment and prevention strategies. However, modelling human oral ARV administration is logistically challenging and fraught by limited adherence. Here, we developed a protocol for administering daily oral doses of ARVs to macaques with a high rate of compliance.

Methods

Parameters of positive reinforcement training (PRT), behavioral responses and optimal drug delivery foods were defined in 7 male rhesus macaques (Macaca mulatta). Animals were trained to sit in a specified cage location prior to receiving ARVs, emtricitabine (FTC) and tenofovir alafenamide (TAF), in a blended food mixture, which was followed immediately with a juice chaser. Consistency of daily oral adherence was evaluated in 4 trained macaques receiving clinically equivalent doses of FTC and TAF (20 and 1.5 mg/kg, respectively) in a short-term (1 month) and an extended (6 month) trial. Adherence was monitored using medication diaries and by quantifying intracellular FTC-triphosphate (FTC-TP) and tenofovir-diphosphate (TFV-DP) concentrations in peripheral mononuclear blood cells (PBMCs).

Results

Trained macaques quickly and consistently took daily oral ARVs for 1 month with an average 99.8% observed adherence. Intracellular concentrations of TFV-DP (median = 845.8 fmol/million cells [range, 620.8–1031.3]) and FTC-TP (median = 367.0 fmol/million cells [range, 289.5–413.5) in PBMCs were consistent with high adherence. Extended treatment with select subjects yielded similar observations for three months (99.5% adherence, 352/356 complete doses taken), although a sudden drop in adherence was observed after splenic biopsy surgery.

Conclusions

We demonstrate that trained macaques reliably adhere to a daily oral ARV regimen, although unexpected adherence issues are possible. Our approach, using clinical doses of oral FTC and TAF daily, further refines macaque models of HIV treatment and prevention by mimicking the human route and timing of ARV administration.

Efficacy of Vaginally Administered Gel Containing Emtricitabine and Tenofovir Against Repeated Rectal Simian Human Immunodeficiency Virus Exposures in Macaques

Vaginal microbicides containing antiretrovirals (ARVs) have shown to prevent vaginally acquired human immunodeficiency virus (HIV), but these products may not protect women who engage in anal sex. Intravaginal dosing with ARVs has shown to result in drug exposures in rectal tissues, thus raising the possibility of dual compartment protection. To test this concept, we investigated whether intravaginal dosing with emtricitabine (FTC)/tenofovir (TFV) gel, which fully protected macaques against repeated vaginal exposures to simian human immunodeficiency virus (SHIV), protects against rectal SHIV exposures. Pharmacokinetic studies revealed rapid distribution of FTC and TFV to rectal tissues and luminal fluids, albeit at concentrations 1-2 log10 lower than those in the vaginal compartment. Efficacy measurements against repeated rectal SHIV challenges demonstrated a 4.5-fold reduction in risk of infection in macaques that received intravaginal FTC/TFV compared to placebo gel (P = .047; log-rank test). These data support the concept of dual compartment protection by vaginal dosing and warrants developing ARV-based vaginal products with improved bidirectional dosing.

Short Communication: Reduced Nevirapine Concentrations Among HIV-Positive Women Receiving Mefloquine for Intermittent Preventive Treatment for Malaria Control During Pregnancy

Clinical trials demonstrated intermittent preventive treatment in pregnancy with mefloquine (MQ) reduced malaria rates among pregnant women, yet an unexpected higher risk of mother-to-child transmission (MTCT) of HIV among HIV-positive women receiving MQ has also been observed. To determine if interactions between antiretroviral drugs (ARVs) and MQ could contribute to the increased MTCT observed in women receiving MQ, we performed a retrospective cross-sectional analysis of ARV plasma concentrations in peripheral blood (maternal plasma) and cord blood (cord plasma) collected at delivery from 186 mothers participating in a randomized clinical trial of MQ (n = 102) compared with placebo (n = 84) in Kenya. Plasma zidovudine (AZT), lamivudine (3TC), and nevirapine (NVP) concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry. Although only 4% (7/186) reported not using these ARVs, AZT, 3TC, and NVP were all below the limit of detection in 44% of maternal plasma and 42% of cord plasma samples, and proportions were similar between the two study arms. Median concentrations of AZT and 3TC were not significantly lower in the MQ arm compared with the placebo arm for maternal plasma and cord plasma (p > .05). However, median NVP concentrations were significantly lower in the MQ study arm compared with the placebo study arm in both maternal plasma (1,597 ng/mL vs. 2,353 ng/mL, Mann-Whitney Rank Sum, p = .023) and cord plasma (2,038 ng/mL vs. 2,434 ng/mL, p = .048). Reduced NVP concentrations in maternal and cord plasma of women receiving MQ suggest MQ may affect NVP metabolism for both mother and infant. These results highlight the need to evaluate potential drug-drug interactions between candidate antimalarials and ARVs for use in pregnant women.

Repeated rectal application of a hyperosmolar lubricant is associated with microbiota shifts but does not affect PrEP drug concentrations: results from a randomized trial in men who have sex with men

INTRODUCTION

Oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) is highly effective in preventing HIV infection among men who have sex with men (MSM). The effects of consistent personal lubricant use in the rectum on tissue PrEP drug concentrations and the rectal microbiota are unknown. We investigated rectal PrEP drug concentrations and the microbiota in MSM before and after repeated rectal application of a hyperosmolar lubricant.

METHODS

We randomized 60 HIV-negative MSM to apply 4 mL of hyperosmolar rectal lubricant daily (n = 20), take daily oral TDF/FTC (n = 19), or both (n = 21) for seven days. Blood, rectal biopsies and rectal secretions were collected via rigid sigmoidoscopy before and on day 8 after product use. Tenofovir (TFV) and FTC as well as their intracellular metabolites tenofovir-diphosphate (TFV-DP), FTC-triphosphate (FTC-TP) were measured by HPLC-mass spectrometry. Rectal mucosal microbiota was sequenced with 16S rRNA sequencing using Illumina MiSeq.

RESULTS

Seven days of lubricant application was not associated with differences in PrEP drug concentrations in rectal tissue or secretions. Lubricant use was associated with a decrease in the relative abundance of the Bacteroides genus (p = 0.01) and a non-significant increase in the Prevotella genus (p = 0.09) in the rectum. PrEP drug concentrations in rectal tissue and secretions were not associated with microbiota composition or diversity either before or after lubricant use.

CONCLUSIONS

Repeated rectal application of a hyperosmolar lubricant does not affect mucosal PrEP drug concentrations but is associated with changes in the rectal microbiome.

Differential localization of distinct CD4 T cell subsets in the female genital tract during the menstrual cycle is regulated by CCR5

CD4 T cells are essential for optimal immune responses against sexually transmitted infections, yet the composition of the CD4 T cell pool localized in the female genital tract (FGT), and the impact of the menstrual cycle on the CD4 T cell population dynamics in the FGT, remains poorly defined. Here we show the FGT CD4 T cell pool is comprised of distinct subsets of memory CD4 T cells based upon trafficking profile, anatomic regionalization, and effector responses. Based on expression of trafficking and tissue retention markers, FGT CD4 T cells are comprised of both migratory memory (TMM) and resident memory (TRM), with TMM expressing a broad array of trafficking markers that would enable their ability to perform immune surveillance in diverse tissues. Furthermore, these subsets differ in both their regionalization throughout the FGT and in their cytokine responses, notably IL-2 production. The frequency of TMM in the FGT increased during the luteal phase of the menstrual cycle and correlated with increased CCR5 expression on circulating memory CD4 T cells. Using a dual adoptive transfer mouse model, we observed that CCR5-mediated trafficking was required for the localization of memory CD4 T cells to the luminal surface of the FGT. In addition, to test cycle influence on T cell trafficking into the FGT, we administered a CCR5 antagonist to pigtail macaques at different stages of the menstrual cycle and found that inhibition of CCR5 signaling selectively reduced TMM numbers solely at luteal time points. Together, these data provide broader insight into role that distinct tissue resident CD4 T cell subsets play in barrier defenses at the FGT and also demonstrate a role for the menstrual cycle in modulating immune protection through CCR5 signaling.

Combination Emtricitabine and Tenofovir Disoproxil Fumarate Prevents Vaginal Simian/Human Immunodeficiency Virus Infection in Macaques Harboring Chlamydia trachomatis and Trichomonas vaginalis

Genital inflammation associated with sexually transmitted infections increases susceptibility to human immunodeficiency virus (HIV), but it is unclear whether the increased risk can reduce the efficacy of pre-exposure prophylaxis (PrEP). We investigated whether coinfection of macaques with Chlamydia trachomatis and Trichomonas vaginalis decreases the prophylactic efficacy of oral emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF). Macaques were exposed to simian/human immunodeficiency virus (SHIV) vaginally each week for up to 16 weeks and received placebo or FTC/TDF pericoitally. All animals in the placebo group were infected with SHIV, while 4 of 6 PrEP recipients remained uninfected (P= .03). Oral FTC/TDF maintains efficacy in a macaque model of sexually transmitted coinfection, although the infection of 2 macaques signals a modest loss of PrEP activity.

Pharmacokinetic evaluation of tenofovir disoproxil fumarate released from an intravaginal ring in pigtailed macaques after 6 months of continuous use

BACKGROUND AND METHODS

A reservoir intravaginal ring (IVR) eluting tenofovir disoproxil fumarate (TDF) was evaluated for 6 months of continuous use in normally cycling female pigtailed macaques with monthly IVR exchanges to define pharmacokinetics and safety.

RESULTS AND CONCLUSIONS

Tenofovir levels in vaginal secretions and tissue remained consistent for 6 months with no adverse safety concerns.

Pharmacokinetic profile of raltegravir, elvitegravir and dolutegravir in plasma and mucosal secretions in rhesus macaques

OBJECTIVES

Pharmacokinetic studies in animal models are important for assessing the prophylactic potential of antiretroviral drugs for HIV prevention. This study sought to identify clinically relevant doses of the marketed integrase inhibitors raltegravir, elvitegravir and dolutegravir in macaques and investigate drug penetration and antiviral activity in mucosal secretions.

METHODS

Macaques received one oral dose of raltegravir, elvitegravir or dolutegravir alone or in combination with emtricitabine and tenofovir disoproxil fumarate followed by drug level measurements in blood and rectal and vaginal secretions. Antiviral activity was investigated in TZM-bl cells exposed to SHIV162p3 in the presence of rectal secretions collected from treated animals.

RESULTS

Plasma drug concentrations with 50 mg/kg raltegravir or elvitegravir were within the range seen in humans receiving 400-800 mg of raltegravir or 800 mg of unboosted elvitegravir but lower than with 150 mg of elvitegravir boosted with cobicistat. AUC0-24 values for dolutegravir increased proportionally with the dose, with a calculated human-equivalent dose of 20 mg/kg. Elvitegravir showed the highest penetration in rectal and vaginal fluids despite the absence of pharmacological boosting, followed by raltegravir and dolutegravir. Rectal secretions collected at 24 h from treated macaques blocked infection of TZM-bl cells by 50% at dilutions of 1/1000 (raltegravir), 1/800 (dolutegravir) and >1/30 000 (elvitegravir).

CONCLUSIONS

We defined macaque doses of HIV integrase inhibitors that recapitulate human clinical doses, which will facilitate efficacy and dose escalation studies in macaques. High and sustained drug concentrations and activity in mucosal secretions suggest that integrase inhibitors are promising candidates for HIV prevention.

Naringenin inhibits the growth of Dictyostelium and MDCK-derived cysts in a TRPP2 (polycystin-2)-dependent manner

BACKGROUND AND PURPOSE

Identifying and characterizing potential new therapeutic agents to target cell proliferation may provide improved treatments for neoplastic disorders such as cancer and polycystic diseases.

EXPERIMENTAL APPROACH

We used the simple, tractable biomedical model Dictyostelium to investigate the molecular mechanism of naringenin, a dietary flavonoid with antiproliferative and chemopreventive actions in vitro and in animal models of carcinogenesis. We then translated these results to a mammalian kidney model, Madin-Darby canine kidney (MDCK) tubule cells, grown in culture and as cysts in a collagen matrix.

KEY RESULTS

Naringenin inhibited Dictyostelium growth, but not development. Screening of a library of random gene knockout mutants identified a mutant lacking TRPP2 (polycystin-2) that was resistant to the effect of naringenin on growth and random cell movement. TRPP2 is a divalent transient receptor potential cation channel, where mutations in the protein give rise to type 2 autosomal dominant polycystic kidney disease (ADPKD). Naringenin inhibited MDCK cell growth and inhibited cyst growth. Knockdown of TRPP2 levels by siRNA in this model conferred partial resistance to naringenin such that cysts treated with 3 and 10 μM naringenin were larger following TRPP2 knockdown compared with controls. Naringenin did not affect chloride secretion.

CONCLUSIONS AND IMPLICATIONS

The action of naringenin on cell growth in the phylogenetically diverse systems of Dictyostelium and mammalian kidney cells, suggests a conserved effect mediated by TRPP2 (polycystin-2). Further studies will investigate naringenin as a potential new therapeutic agent in ADPKD.

Evaluation of the lymphocyte trafficking drug FTY720 in vaginal tissues

BACKGROUND

FTY720 is an immunomodulatory agent that reduces lymphocytes in peripheral tissues and circulation. Such agents may be effective as vaginal microbicides for HIV prevention. Systemic or vaginal application of FTY720 may reduce lymphocyte concentrations in genital tissues, reducing HIV target cell numbers.

METHODS

Five female pigtail macaques received topical vaginal gel FTY720 (n = 2), intravenous (i.v.) FTY720 (n = 2), or placebo gel (n = 1) in this pilot study. Circulating and mucosal lymphocytes and genital mucosa, cytokines, and tissue histology were analyzed to document topical and i.v. FTY720 effects.

RESULTS

Topical and i.v. FTY720 appeared to decrease the levels of cervicovaginal IL-8, IL-1ra, and genital inflammatory cells. Small sample size precluded statistical analysis. Topical administration had no overt adverse effects.

CONCLUSIONS

This study introduces FTY720 as an immunomodulatory agent for the vaginal mucosa, compares topical effects to those of i.v. administration, and provides the basis for future studies involving FTY720 for HIV prevention.

In vitro activities of RWJ-54428 (MC-02,479) against multiresistant gram-positive bacteria

RWJ-54428 (MC-02,479) is a new cephalosporin with a high level of activity against gram-positive bacteria. In a broth microdilution susceptibility test against methicillin-resistant Staphylococcus aureus (MRSA), RWJ-54428 was as active as vancomycin, with an MIC at which 90% of isolates are inhibited (MIC(90)) of 2 microg/ml. For coagulase-negative staphylococci, RWJ-54428 was 32 times more active than imipenem, with an MIC(90) of 2 microg/ml. RWJ-54428 was active against S. aureus, Staphylococcus epidermidis, and Staphylococcus haemolyticus isolates with reduced susceptibility to glycopeptides (RWJ-54428 MIC range, < or = 0.0625 to 1 microg/ml). RWJ-54428 was eight times more potent than methicillin and cefotaxime against methicillin-susceptible S. aureus (MIC(90), 0.5 microg/ml). For ampicillin-susceptible Enterococcus faecalis (including vancomycin-resistant and high-level aminoglycoside-resistant strains), RWJ-54428 had an MIC(90) of 0.125 microg/ml. RWJ-54428 was also active against Enterococcus faecium, including vancomycin-, gentamicin-, and ciprofloxacin-resistant strains. The potency against enterococci correlated with ampicillin susceptibility; RWJ-54428 MICs ranged between < or = 0.0625 and 1 microg/ml for ampicillin-susceptible strains and 0.125 and 8 microg/ml for ampicillin-resistant strains. RWJ-54428 was more active than penicillin G and cefotaxime against penicillin-resistant, -intermediate, and -susceptible strains of Streptococcus pneumoniae (MIC(90)s, 0.25, 0.125, and < or = 0.0625 microg/ml, respectively). RWJ-54428 was only marginally active against most gram-negative bacteria; however, significant activity was observed against Haemophilus influenzae and Moraxella catarrhalis (MIC(90)s, 0.25 and 0.5 microg/ml, respectively). This survey of the susceptibilities of more than 1,000 multidrug-resistant gram-positive isolates to RWJ-54428 indicates that this new cephalosporin has the potential to be useful in the treatment of infections due to gram-positive bacteria, including strains resistant to currently available antimicrobials.

Embryonic lethality and radiation hypersensitivity mediated by Rad51 in mice lacking Brca2

Inherited mutations in the human BRCA2 gene cause about half of the cases of early-onset breast cancer. The embryonic expression pattern of the mouse Brca2 gene is now defined and an interaction identified of the Brca2 protein with the DNA-repair protein Rad51. Developmental arrest in Brca2-deficient embryos, their radiation sensitivity, and the association of Brca2 with Rad51 indicate that Brca2 may be an essential cofactor in the Rad51-dependent DNA repair of double-strand breaks, thereby explaining the tumour-suppressor function of Brca2.

Interaction between caffeine intake and heart zinc concentrations in the rat

The purpose of the present study was to determine the levels of zinc in the hearts of growing post-weaning offspring, fetuses and their dams chronically fed caffeine. A further study was conducted to determine the distribution of Zn in subcellular heart fractions affected by acutely injecting caffeine into the veins of the adult rats. After delivery pups were raised on a 200 g protein/kg diet until day 22 of weaning. On day 22 randomly selected male offspring from each litter were divided into two groups. Group 1 was fed continuously on the same diet as a control, whereas in the experimental group offspring were fed on a 200 g protein/kg diet supplemented with caffeine (20 mg/kg). On day 49 the animals were killed and Zn, calcium and magnesium concentrations of the hearts were measured. In the second series of studies pregnant dams were randomly divided into two groups. Group 1 was fed on a 200 g protein/kg diet from day 3 of gestation, whereas in the experimental group dams were fed on the diet supplemented with caffeine. On day 22 of gestation the fetuses were surgically removed. The Zn, Ca and Mg concentrations of hearts of fetuses and dams were determined. In the third phase a caffeine solution was injected into the vein. After 45 min the hearts were removed and Zn levels in the subcellular fractions determined. The hearts of the growing offspring fed on a caffeine-supplemented diet consistently showed decreased Zn and Ca levels compared with the non-caffeine group.(ABSTRACT TRUNCATED AT 250 WORDS)