Sexual behaviour and incidence of sexually transmitted infections among men who have sex with men (MSM) using daily and event-driven pre-exposure prophylaxis (PrEP): Four-year follow-up of the Amsterdam PrEP (AMPrEP) demonstration project cohort.

BACKGROUND: An increasing number of countries are currently implementing or scaling-up HIV pre-exposure prophylaxis (PrEP) care. With the introduction of PrEP, there was apprehension that condom use would decline and sexually transmitted infections (STIs) would increase. To inform sexual health counselling and STI screening programmes, we aimed to study sexual behaviour and STI incidence among men who have sex with men (MSM) and transgender women who use long-term daily or event-driven PrEP. METHODS AND FINDINGS: The Amsterdam PrEP demonstration project (AMPrEP) was a prospective, closed cohort study, providing oral daily PrEP and event-driven PrEP to MSM and transgender women from 2015 to 2020. Participants could choose their PrEP regimen and could switch at each three-monthly visit. STI testing occurred at and, upon request, in-between 3-monthly study visits. We assessed changes in numbers of sex partners and condomless anal sex (CAS) acts with casual partners over time using negative binomial regression, adjusted for age. We assessed HIV incidence and changes in incidence rates (IRs) of any STI (i.e., chlamydia, gonorrhoea, or infectious syphilis) and individual STIs over time using Poisson regression, adjusted for age and testing frequency. A total of 367 participants (365 MSM) commenced PrEP and were followed for a median 3.9 years (interquartile range [IQR] = 3.4-4.0). Median age was 40 years (IQR = 32-48), 315 participants (85.8%) self-declared ethnicity as white and 280 (76.3%) had a university or university of applied sciences degree. Overall median number of sex partners (past 3 months) was 13 (IQR = 6-26) and decreased per additional year on PrEP (adjusted rate ratio [aRR] = 0.86/year, 95% confidence interval [CI] = 0.83-0.88). Overall median number of CAS acts with casual partners (past 3 months) was 10 (IQR = 3-20.5) and also decreased (aRR = 0.92/year, 95% CI = 0.88-0.97). We diagnosed any STI in 1,092 consultations during 1,258 person years, resulting in an IR of 87/100 person years (95% CI = 82-92). IRs of any STI did not increase over time for daily PrEP or event-driven PrEP users. Two daily PrEP users, and no event-driven PrEP users, were diagnosed with HIV during their first year on PrEP. Study limitations include censoring follow-up due to COVID-19 measures and an underrepresentation of younger, non-white, practically educated, and transgender individuals. CONCLUSIONS: In this prospective cohort with a comparatively long follow-up period of 4 years, we observed very low HIV incidence and decreases in the numbers of casual sex partners and CAS acts over time. Although the STI incidence was high, it did not increase over time. TRIAL REGISTRATION: The study was registered at the Netherlands Trial Register (NL5413) https://www.onderzoekmetmensen.nl/en/trial/22706.

Cumulative tenofovir exposure among patients with human immunodeficiency virus/hepatitis B co-infection with differential viral suppression.

This case-control study explored cumulative tenofovir exposure among patients with HIV/HBV co-infection with HIV viral suppression. Among patients taking tenofovir disoproxil fumarate, median TFV-DP levels in dried blood spots were ∼3-fold lower among patients with incomplete HBV viral suppression (n=4) compared to those with complete suppression (n=5) (516 vs.1456 fmol/punch).

Drug concentrations in hair and dried blood spots as PrEP adherence metrics during pregnancy and postpartum.

We evaluated hair tenofovir (TFV) concentrations as an adherence metric for HIV pre-exposure prophylaxis (PrEP) during pregnancy and postpartum and compared hair levels with tenofovir-diphosphate (TFV-DP) levels in dried blood spots (DBS). Overall, 152 hair samples from 102 women and 36 hair-DBS paired samples from 29 women were collected from a subset of women in a cluster randomized trial. Having a partner known to be living with HIV was associated with higher hair TFV levels (p<0.001). Hair TFV concentrations were strongly correlated with DBS TFV-DP levels (r=0.76, p<0.001), indicating hair as promising cumulative adherence metric for perinatal PrEP assessment.

A Phase 1 Clinical Trial to Assess the Safety and Pharmacokinetics of a Tenofovir Alafenamide/Elvitegravir Insert Administered Rectally for HIV Prevention.

BACKGROUND: On-demand topical products could be an important tool for HIV prevention. We evaluated the safety, pharmacokinetics, and ex vivo pharmacodynamics of a tenofovir alafenamide/elvitegravir (TAF/EVG; 16 mg/20 mg) insert administered rectally. METHODS: MTN-039 was a Phase 1, open-label, single-arm, 2-dose study. Blood, rectal fluid (RF), and rectal tissue (RT) were collected over 72 hours (hr) following rectal administration of one and two TAF/EVG inserts for each participant. ClinicalTrials.gov Identifier: NCT04047420. RESULTS: TAF/EVG inserts were safe and well tolerated. EVG and tenofovir (TFV) were detected in blood plasma at low concentrations: median peak concentrations after 2 inserts were EVG 2.4 ng/mL and TFV 4.4 ng/mL. RT EVG peaked at 2-hr (median 2 inserts= 9 ng/mg) but declined to BLQ in the majority of samples at 24-hr, whereas TFV-DP remained high >2,000 fmol/million cells for 72-hr with 2 inserts. Compared to baseline, median cumulative log10 HIV p24 antigen of ex vivo rectal tissue HIV infection was reduced at each timepoint for both 1 and 2 inserts (p<0.065 and p<0.039, respectively). DISCUSSION: Rectal administration of TAF/EVG inserts achieved high rectal tissue concentrations of EVG and TFV-DP with low systemic drug exposure and demonstrable ex vivo inhibition of HIV infection for 72 hours.

Tenofovir-Diphosphate and Emtricitabine-Triphosphate Adherence Benchmarks in Dried Blood Spots for Persons with HIV Receiving Tenofovir Alafenamide and Emtricitabine-based Antiretroviral Therapy (QUANTI-TAF).

BACKGROUND: QUANTI-TAF aimed to establish tenofovir-diphosphate/emtricitabine-triphosphate (TFV-DP/FTC-TP) adherence benchmarks in dried blood spots (DBS) for persons with HIV (PWH) receiving tenofovir alafenamide/emtricitabine (TAF/FTC)-based antiretroviral therapy (ART). METHODS: During a 16-week pharmacokinetic study, PWH received TAF/FTC-based ART co-encapsulated with an ingestible sensor to directly measure cumulative (enrollment to final visit) and 10-day adherence. At monthly visits, intraerythrocytic concentrations of TAF/FTC anabolites (TFV-DP/FTC-TP) in DBS were quantified by LC-MS/MS and summarized at steady-state (week 12 or 16) as median (IQR). Linear mixed-effects models evaluated factors associated with TFV-DP/FTC-TP. RESULTS: 84 participants (86% male, 11% female, and 4% transgender), predominantly receiving bictegravir/TAF/FTC (73%) enrolled. 92% completed week 12 or 16 (94% receiving unboosted ART). TFV-DP for <85% (7/72), ≥85%-<95% (9/72), and ≥95% (56/72) cumulative adherence was 2696 (2039-4108), 3117 (2332-3339), and 3344 (2605-4293) fmol/punches. All participants with ≥85% cumulative adherence had TFV-DP ≥1800 fmol/punches. Adjusting for cumulative adherence, TFV-DP was higher with boosted ART, lower BMI, and in non-Blacks. FTC-TP for <85% (14/77), ≥85%-<95% (6/77), and ≥95% (57/77) 10-day adherence was 3.52 (2.64-4.48), 4.58 (4.39-5.06), and 4.96 (4.21-6.26) pmol/punches. All participants with ≥85% 10-day adherence had FTC-TP ≥2.5 pmol/punches. Low-level viremia (HIV-1 RNA ≥20-<200 copies/mL) occurred at 60/335 (18%) visits in 33/84 (39%) participants (range: 20-149 copies/mL), with similar TFV-DP (3177 [2494-4149] fmol/punches) compared with HIV-1 RNA <20 copies/mL visits (3279 [2580-4407] fmol/punches). CONCLUSIONS: We propose PK-based TFV-DP (≥1800 fmol/punches)/FTC-TP (≥2.5 pmol/punches) benchmarks in DBS for PWH receiving unboosted TAF/FTC-based ART with ≥85% adherence. In the setting of high adherence, low-level viremia was common.

Concordance between daily diary reported PrEP intake and intraerythrocytic tenofovir diphosphate (TFV-DP) in the Amsterdam PrEP demonstration project.

OBJECTIVE: We assessed the association and concordance between self-reported oral preexposure prophylaxis (PrEP) intake in a diary app and intraerythrocytic drug metabolite concentrations. DESIGN: AMPrEP was a prospective demonstration study providing daily and event-driven PrEP to MSM in Amsterdam, the Netherlands (2015-2020). METHODS: Participants could record their PrEP intake in a diary app. Dried blood spots (DBS) were taken at 6, 12, 24, and 48 months and analysed for tenofovir diphosphate (TFV-DP) and emtricitabine triphosphate (FTC-TP) concentrations. We included TFV-DP measurements preceded by diary completion on at least 90% of days in the 6 weeks prior. We examined the association between self-reported PrEP intake (i.e. number of pills) and TFV-DP concentrations using tobit regression with a random intercept per participant. We also calculated concordance between categorized PrEP intake (i.e. <2, 2-3, 4-6 or 7 pills per week) and categorized TFV-DP concentrations (i.e. <350, 350-699,700-1249 or ≥1250 fmol/punch) using weighted Cohen's kappa. Last, we calculated concordance between self-reported recent PrEP intake (yes/no, in past 2 days) and quantifiability of FTC-TP (yes/no) using Cohen's kappa. RESULTS: Seven hundred and fifty-nine DBS measurements from 282 MSM were included. Self-reported PrEP intake was strongly and positively associated with TFV-DP concentration (ß = 0.77, 95% CI = 0.70-0.84, P < 0.0001). Concordance between categorized PrEP intake and TFV-DP concentration was moderate (κ = 0.44, 95% CI = 0.39-0.50). Concordance between self-reported recent PrEP intake and FTC-TP quantifiability was perfect (κ = 0.83, 95% CI 0.76-0.90). CONCLUSION: Self-reported PrEP intake in a diary app is strongly correlated with actual use, and therefore reliable for comparing PrEP adherence between groups. Still, suboptimal criterion validity according to clinically relevant categories warrants caution when assessing 6-week reported adherence for individuals.

Association of tenofovir diphosphate and lamivudine triphosphate concentrations with HIV and hepatitis B virus viral suppression.

OBJECTIVE: Concentrations of tenofovir diphosphate (TFV-DP) and lamivudine triphosphate (3TC-TP) in cells are correlates of medication adherence and antiviral activity. However, studies have yet to characterize the simultaneous relationship between TFV-DP and 3TC-TP concentrations with HIV and hepatitis B virus (HBV) suppression. METHODS: Individuals with HIV/HBV coinfection on tenofovir disoproxil fumarate (TDF)-containing antiretroviral therapy (ART) were enrolled. Peripheral blood mononuclear cells (PBMCs) and dried blood spots (DBS) samples were collected and steady-state TFV-DP and 3TC-TP concentrations quantified using validated methods. The relationship between patient factors, TFV-DP, and 3TC-TP concentrations in PBMCs and DBS with HBV and HIV viral suppression were examined. RESULTS: Of 138 participants on TDF-containing ART for a median duration (range) of 6 (0.75-15) years, the median age was 43 years and 64% were women. Overall, 128 (92.8%) and 129 (93.5%) had suppressed HIV and HBV viral loads, respectively. Of the 128 participants with suppressed HIV, 122 (95.3%) had suppressed HBV. Self-reported ART adherence, recent change to dolutegravir-based ART, TFV-DP, and 3TC-TP concentrations in PBMCs and DBS were associated with HIV RNA suppression, while HBe antigen positivity, HIV suppression, and TFV-DP concentrations in DBS were associated with HBV DNA suppression (including six persons with HBV nonsuppression and HIV suppression). CONCLUSION: Long-term TDF/3TC-conatining ART was highly efficacious in individuals with HIV/HBV coinfection. Higher TFV-DP concentrations were predictive of suppression for both viruses. Persistent HBV viremia on TDF/3TC-containg ART requires additional research, but may represent poor adherence and the need for adherence interventions or novel antivirals.

Antiviral potency of long-acting islatravir subdermal implant in SHIV-infected macaques.

Treatment nonadherence is a pressing issue in people living with HIV (PLWH), as they require lifelong therapy to maintain viral suppression. Poor adherence leads to antiretroviral (ARV) resistance, transmission to others, AIDS progression, and increased morbidity and mortality. Long-acting (LA) ARV therapy is a promising strategy to combat the clinical drawback of user-dependent dosing. Islatravir (ISL) is a promising candidate for HIV treatment given its long half-life and high potency. Here we show constant ISL release from a subdermal LA nanofluidic implant achieves viral load reduction in SHIV-infected macaques. Specifically, a mean delivery dosage of 0.21 ± 0.07 mg/kg/day yielded a mean viral load reduction of -2.30 ± 0.53 log10 copies/mL at week 2, compared to baseline. The antiviral potency of the ISL delivered from the nanofluidic implant was higher than oral ISL dosed either daily or weekly. At week 3, viral resistance to ISL emerged in 2 out of 8 macaques, attributable to M184V mutation, supporting the need of combining ISL with other ARV for HIV treatment. The ISL implant produced moderate reactivity in the surrounding tissue, indicating tolerability. Overall, we present the ISL subdermal implant as a promising approach for LA ARV treatment in PLWH.

Viral and host mediators of non-suppressible HIV-1 viremia.

Non-suppressible HIV-1 viremia (NSV) is defined as persistent low-level viremia on antiretroviral therapy (ART) without evidence of ART non-adherence or significant drug resistance. Unraveling the mechanisms behind NSV would broaden our understanding of HIV-1 persistence. Here we analyzed plasma virus sequences in eight ART-treated individuals with NSV (88% male) and show that they are composed of large clones without evidence of viral evolution over time in those with longitudinal samples. We defined proviruses that match plasma HIV-1 RNA sequences as 'producer proviruses', and those that did not as 'non-producer proviruses'. Non-suppressible viremia arose from expanded clones of producer proviruses that were significantly larger than the genome-intact proviral reservoir of ART-suppressed individuals. Integration sites of producer proviruses were enriched in proximity to the activating H3K36me3 epigenetic mark. CD4+ T cells from participants with NSV demonstrated upregulation of anti-apoptotic genes and downregulation of pro-apoptotic and type I/II interferon-related pathways. Furthermore, participants with NSV showed significantly lower HIV-specific CD8+ T cell responses compared with untreated viremic controllers with similar viral loads. We identified potential critical host and viral mediators of NSV that may represent targets to disrupt HIV-1 persistence.

Efficacy and safety of long-acting cabotegravir compared with daily oral tenofovir disoproxil fumarate plus emtricitabine to prevent HIV infection in cisgender men and transgender women who have sex with men 1 year after study unblinding: a secondary analysis of the phase 2b and 3 HPTN 083 randomised controlled trial.

BACKGROUND: Injectable cabotegravir was superior to daily oral tenofovir disoproxil fumarate plus emtricitabine for HIV prevention in two clinical trials. Both trials had the primary aim of establishing the HIV prevention efficacy of long-acting injectable cabotegravir pre-exposure prophylaxis (PrEP) compared with tenofovir disoproxil fumarate plus emtricitabine daily oral PrEP. Long-acting PrEP was associated with diagnostic delays and integrase strand-transfer inhibitor (INSTI) resistance. This report presents findings from the first unblinded year of the HIV Prevention Trials Network (HPTN) 083 study. METHODS: The HPTN 083 randomised controlled trial enrolled HIV-uninfected cisgender men and transgender women at elevated HIV risk who have sex with men, from 43 clinical research sites in Africa, Asia, Latin America, and the USA. Inclusion criteria included: a negative HIV serological test at the screening and study entry, undetectable HIV RNA levels within 14 days of study entry, age 18 years or older, overall good health as determined by clinical and laboratory evaluations, and a creatinine clearance of 60 mL/min or higher. Participants were randomly allocated to receive long-acting injectable cabotegravir or daily oral tenofovir disoproxil fumarate plus emtricitabine PrEP. After study unblinding, participants remained on their original regimen awaiting an extension study. HIV infections were characterised retrospectively at a central laboratory. Here we report the secondary analysis of efficacy and safety for the first unblinded year. The primary outcome was incident HIV infection. Efficacy analyses were done on the modified intention-to-treat population using a Cox regression model. Adverse events were compared across treatment groups and time periods (blinded vs unblinded). This trial is registered with ClinicalTrials.gov, NCT02720094. FINDINGS: Of the 4488 participants who contributed person-time to the blinded analysis, 3290 contributed person-time to the first unblinded year analysis between May 15, 2020, and May 14, 2021. Updated HIV incidence in the blinded phase was 0·41 per 100 person-years for long-acting injectable cabotegravir PrEP and 1·29 per 100 person-years for daily oral tenofovir disoproxil fumarate plus emtricitabine PrEP (hazard ratio [HR] 0·31 [95% CI 0·17-0·58], p=0·0003). HIV incidence in the first unblinded year was 0·82 per 100 person-years for long-acting PrEP and 2·27 per 100 person-years for daily oral PrEP (HR 0·35 [0·18-0·69], p=0·002). Adherence to both study products decreased after study unblinding. Additional infections in the long-acting PrEP group included two with on-time injections; three with one or more delayed injections; two detected with long-acting PrEP reinitiation; and 11 more than 6 months after their last injection. Infection within 6 months of cabotegravir exposure was associated with diagnostic delays and INSTI resistance. Adverse events were generally consistent with previous reports; incident hypertension in the long-acting PrEP group requires further investigation. INTERPRETATION: Long-acting injectable cabotegravir PrEP retained high efficacy for HIV prevention in men and transgender women who have sex with men during the first year of open-label follow-up, with a near-identical HR for HIV risk reduction between long-acting injectable cabotegravir and daily oral tenofovir disoproxil fumarate plus emtricitabine PrEP during the first year after unblinding compared with the blinded period. Extended follow-up further defined the risk period for diagnostic delays and emergence of INSTI resistance. FUNDING: Division of AIDS at the National Institute of Allergy and Infectious Diseases, ViiV Healthcare, and Gilead Sciences.

Adults on pre-exposure prophylaxis (tenofovir-emtricitabine) have faster clearance of anti-HIV monoclonal antibody VRC01.

Broadly neutralizing monoclonal antibodies (mAbs) are being developed for HIV-1 prevention. Hence, these mAbs and licensed oral pre-exposure prophylaxis (PrEP) (tenofovir-emtricitabine) can be concomitantly administered in clinical trials. In 48 US participants (men and transgender persons who have sex with men) who received the HIV-1 mAb VRC01 and remained HIV-free in an antibody-mediated-prevention trial (ClinicalTrials.gov #NCT02716675), we conduct a post-hoc analysis and find that VRC01 clearance is 0.08 L/day faster (p = 0.005), and dose-normalized area-under-the-curve of VRC01 serum concentration over-time is 0.29 day/mL lower (p < 0.001) in PrEP users (n = 24) vs. non-PrEP users (n = 24). Consequently, PrEP users are predicted to have 14% lower VRC01 neutralization-mediated prevention efficacy against circulating HIV-1 strains. VRC01 clearance is positively associated (r = 0.33, p = 0.03) with levels of serum intestinal Fatty Acid Binding protein (I-FABP), a marker of epithelial intestinal permeability, which is elevated upon starting PrEP (p = 0.04) and after months of self-reported use (p = 0.001). These findings have implications for the evaluation of future HIV-1 mAbs and postulate a potential mechanism for mAb clearance in the context of PrEP.

Efficacy estimates of oral pre-exposure prophylaxis for HIV prevention in cisgender women with partial adherence.

Pre-exposure prophylaxis (PrEP) with tenofovir (TFV) disoproxil fumarate and emtricitabine administered orally daily is effective in preventing human immunodeficiency virus (HIV) acquisition in both men and women with sufficient adherence; however, the adherence-efficacy relationship in cisgender women has not been well established. We calculated the adherence-efficacy curve for cisgender women by using HIV incidence and plasma TFV concentration data from three trials (FEM-PrEP, VOICE and Partners PrEP). We imputed TFV diphosphate (TFV-DP) concentrations, a measure of long-term adherence, from TFV quantification by using data from the HIV Prevention Trials Network 082 study, which measured both TFV-DP and TFV concentrations. Two, four and seven pills per week reduced HIV incidence by 59.3% (95% credible interval (CrI) 29.9-95.8%), 83.8% (95% CI 51.7-99.8%) and 95.9% (95% CI 72.6-100%), respectively. Our adherence-efficacy curve can be validated and updated by HIV prevention studies that directly measure TFV-DP concentrations. The curve suggests that high adherence confers high protection in cisgender women. However, the lower efficacy with partial adherence highlights the need for new PrEP products and interventions to increase adherence.

The Effect of Disclosure of PrEP Use on Adherence Among African Young Women in an Open-Label PrEP Study: Findings from HPTN 082.

To develop effective PrEP adherence interventions, it is important to understand the interplay between disclosure of pre-exposure prophalxis (PrEP) use, social support, and PrEP adherence. We leveraged the HPTN 082 study conducted among 451 adolescent girls and young women (AGYW) (ages 16 to 25 years, 2016 to 2019) in South Africa and Zimbabwe. Among the 349 who had month three disclosure and PrEP adherence data, 60% (n = 206) felt supported by adults, and 89% (n = 309) disclosed PrEP use to at least one person. PrEP disclosure was not associated with increased adherence, measured by intracellular tenofovir-diphosphate concentrations in dried blood spots. Women who reported having supportive adults, and disclosed to their parents, had higher adherence at 6 months with an increase of 177 fmol/punch (95% CI 12 to 343, t = 2.11, p = 0.04). PrEP interventions that help AGYW identify supportive relationships and effectively communicate the benefits of PrEP may improve PrEP adherence.Clinicaltrials.gov ID number: NCT02732730.

Food Insecurity Is Associated With Low Tenofovir Diphosphate in Dried Blood Spots in South African Persons With HIV.

Background: Food insecurity has been linked to suboptimal antiretroviral therapy (ART) adherence in persons with HIV (PWH). This association has not been evaluated using tenofovir diphosphate (TFV-DP) in dried blood spots (DBSs), a biomarker of cumulative ART adherence and exposure. Methods: Within a prospective South African cohort of treatment-naive PWH initiating ART, a subset of participants with measured TFV-DP in DBS values was assessed for food insecurity status. Bivariate and multivariate median-based regression analysis compared the association between food insecurity and TFV-DP concentrations in DBSs adjusting for age, sex, ethnicity, medication possession ratio (MPR), and estimated glomerular filtration rate. Results: Drug concentrations were available for 285 study participants. Overall, 62 (22%) PWH reported worrying about food insecurity and 44 (15%) reported not having enough food to eat in the last month. The crude median concentrations of TFV-DP in DBSs differed significantly between those who expressed food insecurity worry versus those who did not (599 [interquartile range {IQR}, 417-783] fmol/punch vs 716 [IQR, 453-957] fmol/punch; P = .032). In adjusted median-based regression, those with food insecurity worry had concentrations of TFV-DP that were 155 (95% confidence interval, -275 to -35; P = .012) fmol/punch lower than those who did not report food insecurity worry. Age and MPR remained significantly associated with TFV-DP. Conclusions: In this study, food insecurity worry is associated with lower TFV-DP concentrations in South African PWH. This highlights the role of food insecurity as a social determinant of HIV outcomes including ART failure and resistance.

HIV pre-exposure prophylaxis initiation, persistence, and adherence during pregnancy through the postpartum period.

OBJECTIVE: We evaluated pre-exposure prophylaxis (PrEP) initiation, persistence, and adherence measured via tenofovir-diphosphate (TFV-DP) concentrations in dried blood spots (DBS) among women offered PrEP during pregnancy. METHODS: We prospectively analyzed data from participants in the PrIMA Study (NCT03070600) who were offered PrEP during the second trimester and followed through 9 months postpartum. At follow-up visits (monthly in pregnancy; 6 weeks, 6 months, 9 months postpartum), self-reported PrEP use was assessed, and DBS were collected for quantifying TFV-DP concentrations. RESULTS: In total, 2949 participants were included in the analysis. At enrollment, median age was 24 years [interquartile range IQR) 21-29], gestational age 24 weeks (IQR 20-28), and 4% had a known partner living with HIV. Overall, 405 (14%) participants initiated PrEP in pregnancy with higher frequency among those with risk factors for HIV acquisition, including >2 lifetime sexual partners, syphilis during pregnancy, forced sex, and intimate partner violence ( P  < 0.05). At 9 months postpartum, 58% of PrEP initiators persisted with PrEP use, of which 54% self-reported not missing any PrEP pills in the last 30 days. Among DBS randomly selected from visits where participants persisted with PrEP ( n  = 427), 50% had quantifiable TFV-DP. Quantifiable TFV-DP was twice as likely in pregnancy than postpartum [adjusted risk ratio (aRR) = 1.90, 95% confidence interval (CI) 1.40-2.57, P  < 0.001]. Having a partner known to be living with HIV was the strongest predictor of PrEP initiation, persistence, and quantifiable TFV-DP ( P  < 0.001). CONCLUSIONS: PrEP persistence and adherence waned postpartum, though over half of PrEP initiators persisted through 9-months postpartum. Interventions should prioritize increasing knowledge of partner HIV status and sustaining adherence in the postpartum period.

Long-acting refillable nanofluidic implant confers protection against SHIV infection in nonhuman primates.

The impact of pre-exposure prophylaxis (PrEP) on slowing the global HIV epidemic hinges on effective drugs and delivery platforms. Oral drug regimens are the pillar of HIV PrEP, but variable adherence has spurred development of long-acting delivery systems with the aim of increasing PrEP access, uptake, and persistence. We have developed a long-acting subcutaneous nanofluidic implant that can be refilled transcutaneously for sustained release of the HIV drug islatravir, a nucleoside reverse transcriptase translocation inhibitor that is used for HIV PrEP. In rhesus macaques, the islatravir-eluting implants achieved constant concentrations of islatravir in plasma (median 3.14 nM) and islatravir triphosphate in peripheral blood mononuclear cells (median 0.16 picomole per 106 cells) for more than 20 months. These drug concentrations were above the established PrEP protection threshold. In two unblinded, placebo-controlled studies, islatravir-eluting implants conferred 100% protection against infection with SHIVSF162P3 after repeated low-dose rectal or vaginal challenge in male or female rhesus macaques, respectively, compared to placebo control groups. The islatravir-eluting implants were well tolerated with mild local tissue inflammation and no signs of systemic toxicity over the 20-month study period. This refillable islatravir-eluting implant has potential as a long-acting drug delivery system for HIV PrEP.

Performance of Multiple Adherence Measures for pre-exposure Prophylaxis (PrEP) Among Young Women in Kenya.

Understanding PrEP adherence is key in the formulation of HIV prevention strategies; however, measurement of adherence can be challenging. We compared multiple adherence measures in a two-year study of young Kenyan women at high risk of HIV acquisition. Among 289 participants, concordance between electronic adherence monitoring (EAM) and tenofovir diphosphate (TFV-DP) in dried blood spots ranged from 57 to 72% depending on selected thresholds. Using area under the receiver operating curve, discrimination of quantifiable TFV-DP was high at 0.85 with EAM and low at 0.49-0.54 for multiple self-reported measures. Correlation between EAM and self-reported measures was low (r < 0.11) although correlation within self-reported measures was moderate (r > 0.69). These findings indicate that both TFV-DP and EAM are useful PrEP adherence tools. Adherence would benefit from better availability of less expensive versions of both measurement tools. Additionally, further research on TFV-DP thresholds is needed to inform interpretation and use in understanding PrEP adherence in this population.

RESUMEN: Comprender la adherencia a la PrEP es importante en la formulación de estrategias de prevención del VIH; sin embargo, la medición de la adherencia puede ser difícil. Comparamos múltiples medidas de adherencia en un estudio de dos años de mujeres jóvenes kenianas con alto riesgo de contraer el VIH. Entre 289 participantes, la concordancia entre la monitorización electrónica de la adherencia (EAM) y el tenofovir difosfato (TFV-DP) en las manchas de sangre seca varió del 57% al 72% dependiendo de los umbrales seleccionados. Utilizando el área bajo la curva operativa del receptor, la discriminación de TFV-DP cuantificable fue alta en 0.85 con EAM y baja en 0.49­0.54 para múltiples medidas autoinformadas. La correlación entre la EAM y las medidas autoinformadas fue baja (r < 0,11), aunque la correlación entre de las medidas autoinformadas fue moderada (r > 0,69). Estos resultados indican que tanto TFV-DP como EAM son herramientas útiles de adherencia a la PrEP. La adherencia se beneficiaría de una mejor disponibilidad de versiones menos costosas de ambas herramientas de medición. Además, se necesita más investigación sobre los umbrales TFV-DP para informar la interpretación y el uso en la comprensión de la adherencia a la PrEP en esta población.

A phase I study to assess safety, pharmacokinetics, and pharmacodynamics of a vaginal insert containing tenofovir alafenamide and elvitegravir.

Background: New multi-purpose prevention technology (MPT) products are needed to prevent human immunodeficiency virus (HIV) and herpes simplex virus type 2 (HSV2). In this study, we evaluated a fast-dissolve insert that may be used vaginally or rectally for prevention of infection. Objective: To describe the safety, acceptability, multi-compartment pharmacokinetics (PK), and in vitro modeled pharmacodynamics (PD) after a single vaginal dose of an insert containing tenofovir alafenamide (TAF) and elvitegravir (EVG) in healthy women. Methods: This was a Phase I, open-label, study. Women (n=16) applied one TAF (20mg)/EVG (16mg) vaginal insert and were randomized (1:1) to sample collection time groups for up to 7 days post dosing. Safety was assessed by treatment-emergent adverse events (TEAEs). EVG, TAF and tenofovir (TFV) concentrations were measured in plasma, vaginal fluid and tissue, and TFV-diphosphate (TFV-DP) concentration in vaginal tissue. PD was modeled in vitro by quantifying the change in inhibitory activity of vaginal fluid and vaginal tissue against HIV and HSV2 from baseline to after treatment. Acceptability data was collected by a quantitative survey at baseline and post treatment. Results: The TAF/EVG insert was safe, with all TEAEs graded as mild, and acceptable to participants. Systemic plasma exposure was low, consistent with topical delivery, while high mucosal levels were detected, with median TFV vaginal fluid concentrations exceeding 200,000 ng/mL and 1,000 ng/mL for up to 24 hours and 7 days post dosing, respectively. All participants had vaginal tissue EVG concentrations of > 1 ng/mg at 4 and 24 hours post dosing. The majority had tissue TFV-DP concentrations exceeding 1000 fmol/mg by 24 - 72 hours post dosing. Vaginal fluid inhibition of HIV-1 and HSV-2 in vitro significantly increased from baseline and was similarly high at 4 and 24 hours post dosing. Consistent with high tissue TFV-DP concentrations, p24 HIV antigen production from ectocervical tissues infected ex vivo with HIV-1 significantly decreased from baseline at 4 hours post dosing. HSV-2 production from tissue also decreased post treatment. Conclusions: A single dose of TAF/EVG inserts met PK benchmarks, with PK data supporting an extended window of high mucosal protection. PD modeling supports mucosal protection against both HIV-1 and HSV-2. The inserts were safe and highly acceptable. Clinical trial registration: ClinicalTrials.gov, identifier NCT03762772.

Determinants of adherence to daily PrEP measured as intracellular tenofovir diphosphate concentrations over 24 months of follow-up among men who have sex with men.

OBJECTIVES: Adherence is key to the effectiveness of oral pre-exposure prophylaxis (PrEP) to prevent HIV. Therefore, we aimed to explore factors associated with adherence to daily PrEP (dPrEP). METHODS: Men who have sex with men (MSM) using dPrEP (emtricitabine/tenofovir disoproxil) within the Amsterdam PrEP demonstration project at the Public Health Service of Amsterdam, provided dried blood spots (DBS) 12 and 24 months after PrEP initiation. From DBS, we determined intracellular tenofovir diphosphate (TFV-DP) concentrations to assess adherence; TFV-DP ≥700 fmol/punch was considered adequate. We assessed associations of sociodemographic, clinical and behavioural characteristics with TFV-DP concentrations using multivariable linear regression. RESULTS: Of 263 participants who attended 12-month or 24-month study visits while on dPrEP, 257 (97.7%) provided DBS at one or both visits (492 DBS in total). Median TFV-DP concentration was 1299 (IQR 1021-1627) fmol/punch (12 months: 1332 (1087-1687); 24 months: 1248 (929-1590]). Higher TFV-DP concentrations were associated with: older age (p=0.0008), condomless anal sex with a casual partner in 6 months preceding PrEP initiation (+166 fmol/punch; 95% CI 36.5 to 296) and using a mobile application providing visualised feedback on PrEP use and sexual behaviour (+146 fmol/punch; 95% CI 28.1 to 263). Lower TFV-DP concentrations were associated with longer duration of PrEP use (24 vs 12 months; -91.5 fmol/punch; 95% CI -155 to -28.1). Time-updated number of sex partners, diagnosed STIs and chemsex were not associated with TFV-DP concentrations. CONCLUSIONS: Overall, TFV-DP concentrations were high among MSM using dPrEP, indicating excellent adherence. Especially older participants, those who reported condomless anal sex with a casual partner prior to PrEP initiation and those who used an app with visualised feedback showed higher levels of adherence. As TFV-DP concentrations had decreased slightly at 2 years of PrEP use when compared with 1 year, we emphasise the importance of adherence counselling to those who continue using PrEP. TRIAL REGISTRATION NUMBER: NL5413.