Nondaily preexposure prophylaxis for HIV prevention

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.

Impact of dosing strategies on plasma concentrations of tenofovir: Implications in HIV pre-exposure prophylaxis in China

BACKGROUND

Tenofovir disoproxil fumarate has been recommended for pre-exposure prophylaxis (PrEP) to prevent HIV infection. Several studies have shown short but potent intermittent PrEP could provide comparable protection to daily PrEP in men, suggesting such dosing strategy might be useful in Chinese as well. The objective of this study was to evaluate the impact of different dosing strategies on plasma concentrations of tenofovir.

METHODS

An open label study in 40 Chinese healthy volunteers, randomized to receive the WHO-recommended dose of tenofovir (300mg) at four different dosing intervals: twice weekly for 4 weeks; once daily for 4 weeks with one missing dose in weeks 2-4; once daily for 4 weeks with two missing doses in weeks 2-4; and once every other day for 12 days. Plasma samples were collected at pre-dose, weekly trough and 24h post last dose and assayed using HPLC-UV.

RESULTS

The tenofovir trough concentrations were below the lower limit of quantification with the twice weekly regimen. The trough concentrations (24h dosing interval) at the steady state were 51.7±12.1ng/ml and 53.5±13.8ng/ml (mean±SD) in the once daily groups. Missing doses, once or twice weekly, had no significant impact on trough concentrations. Prolongation of dosing interval to 48h resulted with concentrations at 24h and 48h (trough) of ∼40 and 20ng/ml, respectively.

CONCLUSIONS

Intermittent tenofovir regimens resulted with remarkably low plasma concentrations in Chinese participants. Missing doses did not affect trough concentrations significantly.

Qualitative assessment of readiness for use of HIV pre-exposure prophylaxis among men who have sex with men (MSM) in Malawi: Qualitative study using key informant interviews and focus group discussions

Background

Men who have sex with men (MSM) are a key group for HIV interventions in Malawi considering their high HIV prevalence (17.5% compared to 8.4% among men in the general population). The use of oral preexposure prophylaxis (PrEP) presents a new opportunity for MSM to be protected. We present the findings from a qualitative assessment designed to assess awareness of and willingness and barriers to using PrEP among MSM in Malawi.

Objective

The 3 main objectives of this assessment were to determine: (1) awareness of PrEP, (2) factors that influence willingness to use PrEP, and (3) potential barriers to PrEP use and adherence among MSM in order to guide the design and implementation of a PrEP program in Malawi.

Methods

Ahead of the introduction of PrEP in Malawi, a qualitative study using in-depth interviews (IDIs) and focus group discussions (FGDs) was conducted in October 2018 in Blantyre, Lilongwe, and rural districts of Mzimba North and Mangochi. With support of members of the population, study participants were purposively recruited from 4 MSM-friendly drop-in centers where MSM receive a range of health services to ensure representativeness across sites and age. Participants were asked what they had heard about PrEP, their willingness to use PrEP, their barriers to PrEP use, and their preferences for service delivery. The data were analyzed using a thematic content analysis framework that was predetermined in line with objectives.

Results

A total of 109 MSM were interviewed—13 through IDIs and 96 through FGDs. Most participants were aware of PrEP as a new HIV intervention but had limited knowledge related to its use. However, the majority were willing to use it and were looking forward to having access to it. IDI participants indicated that they will be more willing to take PrEP if the dosing frequency were appropriate and MSM were involved in information giving and distribution of the drug. FGD participants emphasized that places of distribution and characteristics of the service provider are the key factors that will affect use. Knowing the benefits of PrEP emerged as a key theme in both the IDIs and FGDs. Participants highlighted barriers that would hinder them from taking PrEP such as side effects which were cited in IDIs and FGDs. Key factors from FGDs include cost, fear of being outed, drug stockouts, fear of being known as MSMs by wives, and lack of relevant information. FGDs cited stigma from health care workers, forgetfulness, and community associated factors.

Conclusions

Despite having inadequate knowledge about PrEP, study participants were largely willing to use PrEP if available. Programs should include an effective information, education, and communication component around their preferences and provide PrEP in MSM-friendly sites.

Facilitators and barriers of 2-1-1 HIV pre-exposure prophylaxis

An alternative strategy for men who have sex with men (MSM) experiencing challenges with daily HIV pre-exposure prophylaxis (PrEP) includes 2-1-1 dosing. Understanding 2-1-1 PrEP facilitators and barriers, especially during the SARS-CoV-2 pandemic, may guide researchers and healthcare providers in future studies and clinical preparedness. We conducted a national cross-sectional study of MSM in the US who had taken 2-1-1 PrEP to examine facilitators and barriers of this on-demand PrEP dosing option. With the shelter-in-place orders in March 2020, this study was adapted to include questions on how the SARS-CoV-2 pandemic affected participants' PrEP use. A total of 140 individuals participated in the survey, 106 of which completed questions pertaining to the SARS-CoV-2 pandemic. The most common reasons for switching from once-daily to 2-1-1 PrEP included having sex less frequently (63.6%) and wanting to take fewer pills (46.4%). Participants reported high medication adherence based on each component of 2-1-1 PrEP dosing (>84%). The most common barriers with 2-1-1 PrEP dosing included unplanned sexual encounters resulting in missing the double-dose pre-sex (43.6%) and trouble remembering doses post-sex (29.3%). Facilitators of the 2-1-1 PrEP dosing strategy included reductions in sexual encounters (63.6%), preference to take fewer pills (46.4%), need to reduce cost (22.1%), and desire to reduce side effects (19.3%). Challenges to receiving PrEP services during the pandemic included obtaining laboratory testing (25.5%) and PrEP refills (either receipt of a refill authorization from a healthcare provider or processing of a refill from the pharmacy) (18.9%). 2-1-1 PrEP is an effective HIV prevention method; therefore, understanding facilitators and barriers of this dosing strategy can result in continuous provision of HIV prevention efforts, particularly during a pandemic.

Adherence to event-driven HIV PrEP among men who have sex with men in Amsterdam, the Netherlands: analysis based on online diary data, 3-monthly questionnaires and intracellular TFV-DP

INTRODUCTION

Event-driven pre-exposure prophylaxis (edPrEP) with oral tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) is highly effective for preventing HIV acquisition in men who have sex with men (MSM) and is preferred over daily PrEP by some MSM. However, it is largely unknown how well MSM adhere to edPrEP. We then aimed to assess PrEP protection during CAS among MSM using edPrEP and participating in the Amsterdam PrEP demonstration project (AMPrEP).

METHODS

We analysed data from participants enrolled in AMPrEP who were taking edPrEP. We measured adherence through (1) a mobile application in which sexual behaviour and PrEP-use were recorded daily, (2) three-monthly self-completed questionnaires and (3) dried blood spot (DBS) samples collected around six, twelve and twenty-four months after PrEP initiation. We assessed the proportion of days with condomless anal sex (CAS) acts that were protected by PrEP, per partner type (i.e. steady partners, known casual partners, unknown casual partners), and the proportion of three-month periods during which PrEP was correctly used. Intracellular TFV-diphosphate (TFV-DP) concentrations were determined from DBS. Good adherence was defined as at least one tablet before and one tablet within 48 hours after a CAS act.

RESULTS

Between 11 September 2015 and 6 October 2019, 182 of 376 MSM (48.4%) used edPrEP for at least one three-month period. Of the 8224 CAS days that were reported in the app during edPrEP-use, we observed good protection for most CAS days involving steady partners (n = 1625/2455, 66.9%), known casual partners (n = 3216/3472, 92.6%) and unknown casual partners (n = 2074/2297, 90.3%). Men reported consistently correct PrEP-use in 851 (81.4%) of the 1046 three-month periods of edPrEP-use. The median TFV-DP concentration was 591 fmol/sample (interquartile range = 270 to 896).

CONCLUSIONS

Adherence to edPrEP was high as determined from the online app and questionnaire. DBS measurements were consistent with two to three tablets per week on average.

Risk Management on Pre-Exposure Prophylaxis Adherence of Men Who Have Sex with Multiple Men: A Multicenter Prospective Cohort Study

Background

Men who have sex with multiple men (MSMM) belong to a high-risk group for HIV infection, and pre-exposure prophylaxis (PrEP) is an effective measure to prevent the infection. However, few studies on PrEP adherence by MSMM in China exist. We aimed to explore the protective motivation-related factors for PrEP adherence in an HIV-negative MSMM population in Western China and to provide a reference for future risk management and effective prevention strategies.

Methods

Data were collected from a 2-year follow-up cohort study of PrEP in MSM in China. Rogers’ protective motivation theory (PMT) was used to study the PrEP adherence of MSMM, and logistic regression was performed to analyze the influencing factors of PrEP adherence.

Results

A total of 496 MSMM were included in the study: 299 (60.28%) of them in the good adherence group and 197 (39.72%) in the poor adherence group. The threat assessment scores of the good and poor adherence groups were 2.15 ± 0.59 and 2.06 ± 0.47, respectively, and the response assessment scores were 2.81 ± 0.62 and 2.74 ±0.62, respectively. Poor PrEP adherence was associated with on-demand PrEP medication (OR=0.670), students at school (OR=1.837), occasional condom use (OR=1.621), and good HIV knowledge (OR= 0.659). The higher the threat assessment score, the higher the susceptibility; and the lower the response cost, the stronger the protection motivation and the less likely MSMM were to have poor adherence.

Conclusion

On-demand PrEP medication is more conducive to adherence. Preventive management should focus on MSMMs who are students at school, those who occasionally use condoms, and those with poor HIV knowledge. Improving threat perception and susceptibility, and controlling and reducing the response cost can effectively improve PrEP adherence, and the subsequent application of PMT during intervention research can provide a reference for HIV prevention in MSMM.

Preventive efficacy of a tenofovir alafenamide fumarate nanofluidic implant in SHIV-challenged nonhuman primates

Pre-exposure prophylaxis (PrEP) using antiretroviral oral drugs is effective at preventing HIV transmission when individuals adhere to the dosing regimen. Tenofovir alafenamide (TAF) is a potent antiretroviral drug, with numerous long-acting (LA) delivery systems under development to improve PrEP adherence. However, none has undergone preventive efficacy assessment. Here we show that LA TAF using a novel subcutaneous nanofluidic implant (nTAF) confers partial protection from HIV transmission. We demonstrate that sustained subcutaneous delivery through nTAF in rhesus macaques maintained tenofovir diphosphate concentration at a median of 390.00 fmol/106 peripheral blood mononuclear cells, 9 times above clinically protective levels. In a non-blinded, placebo-controlled rhesus macaque study with repeated low-dose rectal SHIVSF162P3 challenge, the nTAF cohort had a 62.50% reduction (95% CI: 1.72% to 85.69%; p=0.068) in risk of infection per exposure compared to the control. Our finding mirrors that of tenofovir disoproxil fumarate (TDF) monotherapy, where 60.00% protective efficacy was observed in macaques, and clinically, 67.00% reduction in risk with 86.00% preventive efficacy in individuals with detectable drug in the plasma. Overall, our nanofluidic technology shows potential as a subcutaneous delivery platform for long-term PrEP and provides insights for clinical implementation of LA TAF for HIV prevention.

Nondaily Use of HIV Preexposure Prophylaxis in a Large Online Survey of Primarily Men Who Have Sex With Men in the United States

BACKGROUND

Event-driven dosing of HIV preexposure prophylaxis (PrEP) using a 2-1-1 regimen is efficacious for men who have sex with men (MSM). However, data are limited on the prevalence, correlates, and patterns of nondaily PrEP use in the United States.

SETTING

Nationwide online survey.

METHODS

We distributed a survey to assess experiences with PrEP, including nondaily use, in May 2019 on geosocial networking sites commonly used by MSM.

RESULTS

Among 9697 respondents, the mean age was 43 years, 67% were non-Hispanic white, and 90% were MSM. Nearly all (91.0%) had heard of PrEP, 40.1% ever used PrEP, and 33.3% used PrEP in the past 6 months. Most (60.6%) were interested in nondaily PrEP. Those without health insurance and those with higher incomes were more likely to be interested in nondaily PrEP. Of the 3232 who used PrEP in the past 6 months, 176 (5.4%) reported nondaily use. Fewer sexual partners, frequent sex planning, and substance use were associated with nondaily use. Common reasons for nondaily use were inconsistent sexual activity (59%) and cost (49%). The most prevalent regimen was event driven (48.3%); of those, 64.7% used 2-1-1. Of nondaily users, 24.0% used PrEP on a regular schedule but not every day, including only on weekends or days starting with T or S.

CONCLUSIONS

Given substantial interest in nondaily PrEP, and use of nondaily strategies that have not been evaluated in clinical studies, there is a need for US public health authorities to provide guidance on safe and effective nondaily dosing for MSM.

PrEP 1.0 and Beyond: Optimizing a Biobehavioral Intervention

Tenofovir disoproxil fumarate coformulated with emtricitabine (TDF/FTC) was shown to be effective in preventing HIV acquisition when used for pre-exposure prophylaxis (PrEP), but questions have arisen regarding optimal PrEP implementation strategies.

On-Demand Oral Pre-exposure Prophylaxis with Tenofovir/Emtricitabine: What Every Clinician Needs to Know

Based on the results of the IPERGAY study, on-demand HIV pre-exposure prophylaxis (PrEP; also known as "non-daily PrEP," "event-driven PrEP," or "2-1-1 PrEP") is being requested more frequently by patients who have intermittent sexual risk or are unable/unwilling to take daily PrEP; therefore, clinicians will be increasingly required to familiarize themselves with its appropriate use. In this perspective, we summarize data related to on-demand PrEP, describe advantages and disadvantages for this alternative dosing strategy, and provide clinical counseling points.

Urine Assay to Measure Tenofovir Concentrations in Patients Taking Tenofovir Alafenamide

Background: HIV pre-exposure prophylaxis (PrEP) with tenofovir/emtricitabine is effective when taken daily. Previously, we developed a urine assay capable of detecting the prodrug tenofovir (TFV) in patients taking tenofovir disoproxil fumarate (TDF)-based PrEP. However, tenofovir alafenamide (TAF) has replaced TDF due to its different safety profile for HIV treatment and was recently approved as PrEP. Given the need to ensure the aforementioned assay remains available for the purpose of objective adherence monitoring, it is critical to ensure its accuracy for detecting TFV in patients taking TAF. Methods: Blood and urine samples were collected from 3 cohorts of patients: (1) 10 participants living with HIV (PLWH) with suppressed virus on a TAF-based regimen, (2) 10 HIV-participants administered 1 dose of TAF/FTC followed by urine and plasma sampling for 7 days starting 1-3 h post-dose, and (3) 10 HIV-participants administered 7 doses of TAF/FTC followed by urine and plasma sampling for 10 days starting 1-3 h after the last dose. Samples were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with high sensitivity and specificity for TFV. HIV-samples were compared to a historical cohort administered one dose of TDF/FTC. Results: PLWH were 90% male, 40% African American, and 10% Hispanic (mean age = 57 y; SD 8.88 y). HIV-participants were 55% male and 70% Caucasian (mean age = 31.6 y; SD 7.70 y). Samples from PLWH demonstrated TFV concentrations 2 logs higher in urine than plasma (1,000 ng/mL vs ±10 ng/mL) at the time of collection. Urine samples following a single dose of TAF in HIV-participants yielded TFV concentrations ranging from 100 to 1,000 ng/mL 1-3 h post-dose and remained >100 ng/mL for 6 days in 8 of 10 participants. Urine samples collected after 7 consecutive doses of TAF yielded TFV concentrations >1,000 ng/mL 1-3 h after dosing discontinuation, with TFV concentrations >1,00 ng/mL 7 days post discontinuation in 8 of 10 participants. Urine TFV concentrations following TAF administration were comparable to those from a historical cohort administered TDF/FTC. Plasma TFV concentrations were low(±10 ng/mL) in both HIV-cohorts at all time points. Conclusions: TFV persists in urine at detectable concentrations in participants taking TAF/FTC for at least 7 days despite largely undetectable plasma concentrations, with urine TFV concentrations comparable to patients taking TDF/FTC. This study demonstrates the ability of a urine TFV assay to measure recent TAF adherence.

Inhibitory Effects of Probenecid on Pharmacokinetics of Tenofovir Disoproxil Fumarate and Emtricitabine for On-Demand HIV Preexposure Prophylaxis

In a randomized, crossover pharmacokinetic study in healthy volunteers (N = 14), a single dose of 2 g probenecid (PRO)-boosted 600 mg tenofovir disoproxil fumarate (TDF)/400 mg emtricitabine (FTC) (test (T) +PRO) was compared with the current on-demand HIV preexposure prophylaxis from the IPERGAY study (a 600 mg TDF/400 mg FTC on day 1 and 300 mg TDF/200 mg FTC on days 2 and 3) (control, C IPERGAY). PRO increased mean single-dose area under the plasma concentration-time curve extrapolated to infinity (AUC_0-∞,SD ) of tenofovir (TFV) and FTC by 61% and 68%, respectively. The TFV-diphosphate (TFV-DP) concentrations in peripheral blood mononuclear cells were higher (~30%) at 24 hours in T +PRO but then fell significantly lower (~40%) at 72 hours compared with C IPERGAY. The interaction between FTC and PRO was unexpected and novel. Further study is needed to determine if this PRO-boosted TDF/FTC regimen would be clinically effective.

Probenecid-Boosted Tenofovir: A Physiologically-Based Pharmacokinetic Model-Informed Strategy for On-Demand HIV Preexposure Prophylaxis

Multiple doses of tenofovir disoproxil fumarate (TDF) together with emtricitabine is effective for HIV preexposure prophylaxis (PrEP). TDF is converted to tenofovir (TFV) in circulation, which is subsequently cleared via tubular secretion by organic ion transporters (OATs; OAT1 and OAT3). Using in vitro kinetic parameters for TFV and the OAT1 and OAT3 inhibitor probenecid, a bottom‐up physiologically‐based pharmacokinetic model was successfully developed for the first time that accurately describes the probenecid–TFV interaction. This model predicted an increase in TFV plasma exposure by 60%, which was within 15% of the observed clinical pharmacokinetic data, and a threefold decrease in renal cells exposure following coadministration of a 600 mg TDF dose with 2 g probenecid. When compared with multiple‐dose regimens, a single‐dose probenecid‐boosted TDF regimen may be effective for HIV PrEP and improve adherence and safety by minimizing TFV‐induced nephrotoxicity by reducing TFV accumulation in renal cells.

Daily and event-driven pre-exposure prophylaxis for men who have sex with men in Belgium: results of a prospective cohort measuring adherence, sexual behaviour and STI incidence

INTRODUCTION

Pre-Exposure Prophylaxis (PrEP) is highly effective in reducing the risk for HIV infection among men who have sex with men (MSM) and may have an important impact in slowing down the HIV epidemic. Concerns remain however about low adherence, increased risk behaviour and reduced condom use when using PrEP. The aim of this study was to assess these factors prospectively among MSM using daily and event-driven PrEP in Belgium.

METHODS

An open-label prospective cohort study was conducted from October 2017 to May 2018 at the Institute of Tropical Medicine, in Antwerp, Belgium. At enrolment, MSM at high risk for HIV chose between daily or event-driven PrEP. They were allowed to switch regimens or stop taking PrEP at each of their tri-monthly visits. Data were collected on an electronic case report form, web-based diary and self-administered questionnaire. Screening for HIV and other Sexually Transmitted Infections (STIs) was also performed.

RESULTS

Two hundred MSM were followed up for a total duration of 318 person-years. At month 18, 75.4% of the participants were on daily and 24.6% were on event-driven PrEP. The mean proportion of covered sex acts by PrEP for the complete follow-up period was 91.5% for all participants, 96.5% for daily and 67.0% for event-driven PrEP use. The number of casual and anonymous sex partners was significantly higher for daily users, as compared with event-driven users, but did not change over time. In contrast, the mean proportion of condomless receptive anal intercourse with casual and anonymous partners increased significantly during follow-up, for both daily and event-driven use (p < 0.0001 for all 4 trends). No new HIV infection was diagnosed during follow-up. The incidence of bacterial STIs was 75.4 per 100 person-years (95% CI 63.8 to 89.1). We did not detect a significant change in N. gonorrhoeae/C. trachomatis incidence over time. The incidence of hepatitis C was 2.9 per 100 person-years.

CONCLUSIONS

PrEP is an effective and well adopted HIV prevention tool for MSM in Belgium. Participants adapted daily and event-driven regimens to their own needs and were able to adapt their PrEP adherence to risk exposure.

Curlin M, Holtz TH, Mannheimer S, Marzinke MA, Amico KR, Liu A, Piwowar-Manning E, Eshleman SH, Dye BJ, Gandhi M, Grant RM. Short- and Long-Term Pharmacologic Measures of HIV Pre-exposure Prophylaxis Use Among High-Risk Men Who Have Sex With Men in HPTN 067/ADAPT

BACKGROUND

The effectiveness of oral emtricitabine (FTC)/tenofovir (TFV) disoproxil fumarate-based HIV pre-exposure prophylaxis (PrEP) depends on adherence. Pharmacologic measures help interpret patterns and predictors of PrEP adherence.

SETTING

We analyzed data from the subsample of men who have sex with men enrolled in HPTN 067/ADAPT in Bangkok, Thailand, and Harlem, NY, U.S.

METHODS

After a 5-week directly observed therapy period, participants were randomized to daily, time-driven, or event-driven PrEP. Follow-up occurred at weeks 4, 12, and 24 after randomization. Plasma and hair FTC/TFV levels indicated short- and long-term PrEP use, respectively. Electronic pill bottle data (Wisepill) were collected weekly. Pearson correlation coefficients between PrEP use measures were calculated; linear mixed models assessed predictors of plasma and hair drug concentrations.

RESULTS

Among 350 participants (median age: 31 years, interquartile range: 25-38), 49.7% were from Harlem, half had less than college education, and 21% reported heavy alcohol use. In multivariable models, being enrolled in Harlem, being in non-daily arms, and having less than college education were associated with lower hair FTC/TFV concentrations; heavy alcohol use was associated with higher concentrations. Similar results were found for plasma concentrations by site and arm, but older age and greater number of sex partners were associated with higher concentrations. Hair and plasma FTC/TFV concentrations were moderately correlated with Wisepill data (r ≥ 0.29) across visits.

CONCLUSIONS

In HPTN067, plasma, hair, and Wisepill data correlated with one another and served as complementary adherence measures. Site, arm, education, age, alcohol, and sexual behavior influenced patterns of adherence.

Choosing Between Daily and Event-Driven Pre-exposure Prophylaxis: Results of a Belgian PrEP Demonstration Project

BACKGROUND

Daily pre-exposure prophylaxis and event-driven pre-exposure prophylaxis (PrEP) are efficacious in reducing HIV transmission among men who have sex with men (MSM). We analyzed baseline data from a PrEP demonstration project "Be-PrEP-ared" in Antwerp, Belgium, to understand preferences for daily PrEP or event-driven PrEP among MSM at high risk of HIV and factors influencing their initial choice.

METHODS

Cross-sectional data from an open-label prospective cohort study, using mixed methods. Participants who preregistered online were screened for eligibility and tested for sexually transmitted infections (STIs). Eligible participants chose between daily PrEP and event-driven PrEP and reported on behavioral data through an electronic questionnaire. In-depth interviews were conducted with a selected subsample. Bivariate associations were examined between preferred PrEP regimens and sociodemographic factors, sexual behavior, and STIs at screening.

RESULTS

In total, 200 participants were enrolled between October 2015 and December 2016. Self-reported levels of sexual risk-taking before enrollment were high. STI screening revealed that 39.5% had at least 1 bacterial STI. At baseline, 76.5% of participants preferred daily PrEP and 23.5% event-driven PrEP. Feeling able to anticipate HIV risk was the most frequent reason for preferring event-driven PrEP. Regimen choice was associated with sexual risk-taking behavior in the past 3 months. Almost all participants (95.7%) considered it likely that they would change their dosing regimen the following year.

CONCLUSION

Event-driven PrEP was preferred by 23.5% of the participants, which better suits their preventive needs. Event-driven PrEP should be included in PrEP provision as a valuable alternative to daily PrEP for MSM at high risk of HIV.

Predictors of Daily Adherence to HIV Pre-exposure Prophylaxis in Gay/Bisexual Men in the PRELUDE Demonstration Project

Adequate adherence to pre-exposure prophylaxis (PrEP) is critical to prevent HIV infection, but accurately measuring adherence remains challenging. We compared two biological [blood drug concentrations in plasma and peripheral blood mononuclear cells (PBMC)] and two self-reported measures (facilitated recall to clinicians and self-report in online surveys) and identified predictors of daily PrEP adherence among gay and bisexual men (GBM) in their first 12 months on PRELUDE, an open-label, single-arm PrEP demonstration project in New South Wales, Australia. 327 participants were enrolled; 263 GBM attended their 12-month follow-up visit (81% retention). Overall, 91% of blood samples had plasma drug concentrations indicative of taking 7 pills/week, and 99% had protective drug concentrations (≥ 4 pills/week). Facilitated recall to clinicians identified 99% of participants with protective adherence as measured by PBMC drug concentrations. Daily adherence measured by facilitated recall was associated with behavioural practices including group sex (aOR 1.33, 95% CI 1.15-1.53, p < 0.001). Retained participants maintained high adherence to daily PrEP over 12 months, confirmed by four different measures. Facilitated recall to clinicians is a suitable measure for assessing PrEP adherence in populations engaged in care where there is established trust and rapport with patients. Trial registration: ClinicalTrials.gov NCT02206555.

Sexual safety and HIV prevention in travel medicine: Practical considerations and new approaches

Travellers who engage in sexual contact with a new sexual partner abroad may be at high risk of HIV and other sexually transmitted infections (STIs), but these risks can be reduced through appropriate planning during the pre-travel clinic visit. Here we discuss strategies available to the clinician to maximise travellers' sexual safety during travel. Strategies may include immunizations, condoms, HIV pre-exposure prophylaxis (PrEP), HIV post-exposure prophylaxis (PEP), self-initiated treatment of symptomatic bacterial STIs, post-exposure prophylaxis for bacterial STIs and hormonal contraception. We discuss the role of these different strategies for travellers, and provide resources to assist clinicians in making clinical decisions and in educating travellers about sexual safety.

HIV pre-exposure prophylaxis in South East Asia: A focused review on present situation

Pre-exposure prophylaxis (PrEP) with the use of antiretrovirals has been approved for HIV prevention in many western countries and internationally. PrEP is however not yet widely available in South East Asia. Awareness of PrEP among MSM in the region is very variable in different countries. While willingness of PrEP uptake is closely related to the extent of awareness, it is largely affected by factors at the individual level, e.g. financial consideration, risk perception, understanding of PrEP and convenience. Removal of social stigmata and secure data confidentiality can improve willingness of uptake. The diverse religious beliefs in South East Asia could have potential influence on PrEP uptake but there was very limited data in the region. There is no strong evidence suggesting substantial risk compensation among MSM who are on PrEP. As in other parts of the world, education on condom use to prevent other sexually transmitted diseases (STD) should be properly addressed rather than blaming PrEP as a sole cause of rise in STD among MSM.

Acceptability of Injectable and On-Demand Pre-Exposure Prophylaxis Among an Online Sample of Young Men Who Have Sex with Men in California

PURPOSE

Pre-exposure prophylaxis (PrEP) is an effective strategy to prevent HIV. However, low uptake of daily oral PrEP since Food and Drug Administration approval and low medication adherence among users have stimulated the investigation of other modalities for delivery, such as injectable PrEP and on-demand PrEP. The objective of this study was to determine the demographic and behavioral predictors of willingness to try alternative PrEP delivery mechanisms among young men who have sex with men (YMSM) who stated that they were unwilling to try daily oral PrEP.

METHODS

YMSM in California were recruited through geosocial networking applications; we analyzed a subsample who stated that they were either ambivalent about trying or unwilling to try daily oral PrEP (n = 265). We used chi-square and Fisher's exact tests to determine characteristics associated with willingness to try injectable PrEP, willingness to try on-demand PrEP, and willingness to try either alternative form.

RESULTS

For individuals who stated that they would not be willing to try daily oral PrEP, ∼85% were willing to try on-demand and/or injectable PrEP. Individuals who reported some college or more reported greater willingness to try injectable PrEP (adjusted odds ratio [aOR]: 2.92; 95% confidence interval [CI]: 1.32-6.46), on-demand PrEP (aOR: 2.28; 95% CI: 1.06-4.90), or either method (aOR: 5.54; 95% CI: 1.78-17.22).

CONCLUSION

Future research should determine how to enhance uptake of emerging forms of PrEP among the individuals most at risk for HIV.

Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine HIV pre-exposure prophylaxis: clinical guidelines. Update April 2018

Daily use of coformulated tenofovir and emtricitabine for HIV pre-exposure prophylaxis (PrEP) by populations at high risk of HIV infection is now recommended in guidelines from the United States, Europe and Australia and globally through the 2015 WHO guidelines. These 2017 Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine's (ASHM) PrEP Guidelines are an updated adaptation of the 2014 US Centers for Disease Control's PrEP guidelines and are designed to: •Support the prescription of PrEP using forms of coformulated tenofovir and emtricitabine that have been registered in Australia by the Therapeutic Goods Administration and other bioequivalent generic drugs that are available in Australia through self-importation, private prescription or Australian PrEP clinical trials•Assist clinicians in the evaluation of patients who are seeking PrEP•Assist clinicians in commencing and monitoring patients on PrEP including PrEP dosing schedules, management of side-effects and toxicity, use of PrEP in pregnancy and in chronic hepatitis B infection and how to cease PrEP Daily PrEP with co-formulated tenofovir and emtricitabine, used continuously or for shorter periods of time, is recommended in these guidelines as a key HIV-prevention option for men who have sex with men (MSM), transgender men and women, heterosexual men and women, and people who inject drugs (PWID) at substantial risk of HIV acquisition. These guidelines were updated in April 2018 and include changes to the recommendations regarding the choice of daily or on-demand PrEP.

Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine HIV pre-exposure prophylaxis: clinical guidelines. Update April 2018

Daily use of coformulated tenofovir and emtricitabine for HIV pre-exposure prophylaxis (PrEP) by populations at high risk of HIV infection is now recommended in guidelines from the United States, Europe and Australia and globally through the 2015 WHO guidelines. These 2017 Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine's (ASHM) PrEP Guidelines are an updated adaptation of the 2014 US Centers for Disease Control's PrEP guidelines and are designed to: •Support the prescription of PrEP using forms of coformulated tenofovir and emtricitabine that have been registered in Australia by the Therapeutic Goods Administration and other bioequivalent generic drugs that are available in Australia through self-importation, private prescription or Australian PrEP clinical trials•Assist clinicians in the evaluation of patients who are seeking PrEP•Assist clinicians in commencing and monitoring patients on PrEP including PrEP dosing schedules, management of side-effects and toxicity, use of PrEP in pregnancy and in chronic hepatitis B infection and how to cease PrEP Daily PrEP with co-formulated tenofovir and emtricitabine, used continuously or for shorter periods of time, is recommended in these guidelines as a key HIV-prevention option for men who have sex with men (MSM), transgender men and women, heterosexual men and women, and people who inject drugs (PWID) at substantial risk of HIV acquisition. These guidelines were updated in April 2018 and include changes to the recommendations regarding the choice of daily or on-demand PrEP.

Pharmacokinetic and Tissue Distribution Profile of Long Acting Tenofovir Alafenamide and Elvitegravir Loaded Nanoparticles in Humanized Mice Model

PURPOSE

Non-adherence to the antiretroviral (ARV) regimen is a critical factor in determining efficacy of ARV drugs for pre-exposure prophylaxis (PrEP). A long-acting parenteral formulation may be an effective alternative to daily oral dosing. A pharmacokinetic and tissue distribution study of drug-loaded nanoparticle (NP) was performed in female humanized CD34⁺-NSG mice.

METHODS

Mice received 200 mg/kg each of tenofovir alafenamide (TAF) and elvitegravir (EVG) as free drugs (TAF + EVG solution) or as drug loaded NP (TAF + EVG NP) formulation by subcutaneous (SubQ) administration. Plasma and tissue were collected to determine tenofovir (TFV) and EVG concentrations using LC-MS/MS. Non-compartmental analysis was performed using WinNonlin.

RESULTS

SubQ administration of TAF + EVG NP formulation resulted in long residence time and exposure for both drugs. The AUC_(0-72h) of TFV and EVG was 14.1 ± 2.0, 7.2 ± 1.8 μg × hr./mL from drugs in solution (free) and the AUC_(0-14day) for the same drugs was 23.1 ± 4.4, 39.7 ± 6.7 μg × hr./mL from NPs. The observed elimination half-life (t_1/2) for TFV of free and NPs were 14.2 h, 5.1 days and for EVG 10.8 h, 3.3 days, respectively.

CONCLUSION

This study documents that a TAF + EVG NP provides sustained release, which can overcome patient non-adherence to dosing and may facilitate prediction of appropriate protective drug concentration for HIV prophylaxis.

A multiplex assay for detection of SHIV plasma and mucosal IgG and IgA

Evaluating antibody maturation provides valuable data to characterize immune responses to HIV infection and can provide insight into biomedical intervention efficacy. It is important to develop assays that evaluate antibody maturation in both plasma and mucosal compartments. The nonhuman primate model provides a controlled system to collect temporal data that are integral to assessing intervention strategies. We report the development of a novel multiplex assay, based on the Bio-Plex platform, to evaluate plasma and mucosal IgG and IgA avidity and maturation against simian/human immunodeficiency virus (SHIV) in this controlled system. Vaginal mucosa and plasma samples were collected from a prior study evaluating the efficacy of a tenofovir disoproxil fumarate (TDF) intravaginal ring (IVR) against SHIVSF162P3 challenge in female pigtailed macaques. For validation of the multiplex assay, specimens from six SHIV-infected placebo animals and one TDF breakthrough animal were evaluated. For SHIV and HIV envelope analytes, antibody levels and avidity in both compartments continued to mature post-infection. Maturation of IgG and IgA levels was similar in each compartment, however, mucosal antibody levels tended to be more variable. This SHIV assay elucidates IgG/IgA antibody kinetics in the plasma and vaginal mucosa and will be a valuable tool in vaccine and other biomedical intervention studies in the nonhuman primate model.

Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine HIV pre-exposure prophylaxis: clinical guidelines

Daily use of coformulated tenofovir and emtricitabine for HIV pre-exposure prophylaxis (PrEP) by populations at high risk of HIV infection is now recommended in guidelines from the United States, Europe and Australia and globally through the 2015 WHO guidelines. These 2017 Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine's (ASHM) PrEP Guidelines are an updated adaptation of the 2014 US Centers for Disease Control's PrEP guidelines and are designed to: •Support the prescription of PrEP using forms of coformulated tenofovir and emtricitabine that have been registered in Australia by the Therapeutic Goods Administration and other bioequivalent generic drugs that are available in Australia through self-importation, private prescription or Australian PrEP clinical trials•Assist clinicians in the evaluation of patients who are seeking PrEP•Assist clinicians in commencing and monitoring patients on PrEP including PrEP dosing schedules, management of side-effects and toxicity, use of PrEP in pregnancy and in chronic hepatitis B infection and how to cease PrEP Daily PrEP with co-formulated tenofovir and emtricitabine, used continuously or for shorter periods of time, is recommended in these guidelines as a key HIV-prevention option for men who have sex with men (MSM), transgender men and women, heterosexual men and women, and people who inject drugs (PWID) at substantial risk of HIV acquisition.

Pre-exposure prophylaxis (PrEP) for men who have sex with men in Europe: review of evidence for a much needed prevention tool

In many Western countries with good coverage of antiretroviral treatment (ART) programmes the annual number of HIV infections is still high and not (yet) declining among men who have sex with men (MSM). This might indicate that antiretroviral treatment roll-out alone will not turn around the course of the epidemic and that new, additional tools are needed. Antiretrovirals used as prevention tools for people not yet infected with HIV, such as pre-exposure prophylaxis (PrEP) could be such important additional tools. PrEP is a new type of biomedical prevention, which involves the use of antiretrovirals before, during and after (periods of) sexual exposure to HIV. In this review, we will focus on PrEP as a new prevention tool for MSM at high risk in Europe, including its evidence for effectiveness, challenges for implementation, ongoing European demonstration studies; as well as how PrEP relates to other existing prevention tools. In light of European Medicines Agency's recent recommendation for approval of PrEP we briefly review the potential implications.

Cost-effectiveness analysis of pre-exposure prophylaxis for HIV-1 prevention in the Netherlands: a mathematical modelling study

BACKGROUND

Pre-exposure prophylaxis (PrEP) with tenofovir and emtricitabine prevents HIV infections among men who have sex with men (MSM). PrEP can be given on a daily or intermittent basis. Unfortunately, PrEP is not reimbursed in most European countries. Cost-effectiveness analyses of PrEP among MSM in Europe are absent but are key for decision makers to decide upon PrEP implementation.

METHODS

We developed a deterministic mathematical model, calibrated to the well defined Dutch HIV epidemic among MSM, to predict the effect and cost-effectiveness of PrEP. PrEP was targeted to 10% of highly sexually active Dutch MSM over the coming 40 years. Cost-effectiveness ratios were calculated to predict the cost-effectiveness of daily and on-demand PrEP. Cost-effectiveness ratios below €20 000 were considered to be cost-effective in this analysis.

FINDINGS

Within the context of a stable HIV epidemic, at 80% effectiveness and current PrEP pricing, PrEP can cost as much as €11 000 (IQR 9400-14 100) per quality-adjusted life-year (QALY) gained when used daily, or as little as €2000 (IQR 1300-3000) per QALY gained when used on demand. At 80% effectiveness, daily PrEP can be considered cost-saving if the price of PrEP is reduced by 70%, and on-demand PrEP can be considered cost-saving if the price is reduced by 30-40%.

INTERPRETATION

PrEP for HIV prevention among MSM in the Netherlands is cost-effective. The use of PrEP is most cost-effective when the price of PrEP is reduced through on-demand use or through availability of generic PrEP, and can quickly be considered cost-saving.

FUNDING

None.

Intracellular Tenofovir and Emtricitabine Anabolites in Genital, Rectal, and Blood Compartments from First Dose to Steady State

The pharmacokinetics (PK) of tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP), the active anabolites of tenofovir disoproxil fumarate (TDF), and emtricitabine (FTC) in blood, genital, and rectal compartments was determined in HIV-positive and seronegative adults who undertook a 60-day intensive PK study of daily TDF/FTC (plus efavirenz in HIV positives). Lymphocyte cell sorting, genital, and rectal sampling occurred once per subject, at staggered visits. Among 19 HIV-positive (3 female) and 21 seronegative (10 female) adults, TFV-DP in peripheral blood mononuclear cells (PBMC) accumulated 8.6-fold [95% confidence interval (CI): 7.2-10] from first-dose to steady-state concentration (Css) versus 1.7-fold (95% CI: 1.5-1.9) for FTC-TP. Css was reached in ∼11 and 3 days, respectively. Css values were similar between HIV-negative and HIV-positive individuals. Css TFV-DP in rectal mononuclear cells (1,450 fmol/10⁶ cells, 898-2,340) was achieved in 5 days and was >10 times higher than PBMC (95 fmol/10⁶ cells, 85-106), seminal cells (22 fmol/10⁶ cells, 6-79), and cervical cells (111 fmol/10⁶ cells, 64-194). FTC-TP Css was highest in PBMC (5.7 pmol/10⁶ cells, 5.2-6.1) and cervical cells (7 pmol/10⁶ cells, 2-19) versus rectal (0.8 pmol/10⁶ cells, 0.6-1.1) and seminal cells (0.3 pmol/10⁶ cells, 0.2-0.5). Genital drug concentrations on days 1-7 overlapped with estimated Css, but accumulation characteristics were based on limited data. TFV-DP and FTC-TP in cell sorted samples were highest and achieved most rapidly in CD14⁺ compared with CD4⁺, CD8⁺, and CD19⁺ cells. Together, these findings demonstrate cell-type and tissue-dependent cellular pharmacology, preferential accumulation of TFV-DP in rectal mononuclear cells, and rapid distribution into rectal and genital compartments.