Pre-exposure prophylaxis: a useful tool to prevent human immunodeficiency virus infection?

A Comparison of Tenofovir Predose Concentrations in Generic Pre-exposure Prophylaxis Formulations: A Short Communication

BACKGROUND

There is extensive evidence to show that pre-exposure prophylaxis (PrEP) using tenofovir disoproxil fumarate (TDF)-based formulations dramatically reduces the risk of HIV acquisition among individuals without HIV infection. Here, the authors aim to compare tenofovir plasma predose concentrations in subjects taking PrEP daily versus on demand and using different TDF-based generic formulations.

METHODS

Subjects providing informed signed consent for the measurement of tenofovir plasma levels were included in the study. Predose drug concentrations were stratified according to PrEP administration and the type of TDF-based formulation. The control group consisted of patients with HIV infection who were matched for renal function and were administered branded TDF that was not combined with boosted-antiretroviral drugs.

RESULTS

The study consisted of 100 subjects (mean age, 39 ± 10 years; body weight, 77 ± 11 kg). A wide distribution in tenofovir predose concentrations was observed, with values ranging from 17 to 297 ng/mL (coefficient of variation 77%). No significant differences were noted in tenofovir predose concentrations between subjects who were administered PrEP daily (n = 75) or on demand (n = 25) [94 (35-255) versus 104 (37-287) ng/mL; P = 0.476]. Comparable tenofovir predose concentrations were found between patients with HIV infection (n = 220) who were administered branded TDF and those without HIV infection who were treated with 5 different generic TDF-based formulations with generics-to-branded ratios. These were always within the range of 80%-125% and were used to define bioequivalence.

CONCLUSIONS

The marketed generic formulations of TDF delivered tenofovir plasma predose concentrations comparable with those delivered by branded formulations.

Evaluation of Drug Abuse by Hair Analysis and Self-Reported Use Among MSM Under PrEP: Results From a French Substudy of the ANRS-IPERGAY Trial

BACKGROUND

We used the Agence nationale de Recherches sur le sida et les hépatites virales (ANRS)-IPERGAY trial to qualitatively and quantitatively measure drug use among men who have sex with men under preexposure prophylaxis using 2 different methods, to better understand and collectively respond to risky practices.

METHOD

We included 69 volunteers of the ANRS-IPERGAY trial. We measured drug use by 2 methods: (1) drug detection by hair analysis and (2) reported drug use by self-reported drug consumption.

RESULTS

New psychoactive substances (NPS) and conventional drugs were detected in 53 of the 69 (77%) volunteers by hair analysis and in 39 of the 69 (57%) volunteers by questionnaires. On the 219 hair segments analyzed, the most commonly used drugs were cocaine in 47 of the 69 (68%), 3,4-methylenedioxymethamphetamine/ecstasy in 31 of the 69 (45%), and NPS in 27 of the 69 (39%). On the 1061 collected questionnaires, the most commonly used drugs were cocaine in 31 of the 69 (45%), 3,4-methylenedioxymethamphetamine/ecstasy in 29 of the 69 (42%), and NPS in 16 of the 69 (23%). Hair analysis detects more conventional drugs and/or NPS use (P < 0.05). Drug use identified by hair was significantly associated with a higher number of sexual partners in the past 2 months (P ≤ 0.001), more often casual partners (P ≤ 0.001), condomless anal sex (P ≤ 0.005), hardcore sexual practices (P ≤ 0.001), a higher number of sexually transmitted infections, and chemsex (P ≤ 0.05).

CONCLUSIONS

Self-report drug use by questionnaires remains the reference tool for harm reduction at the individual level because of its feasibility and low cost. However, hair analysis is more sensitive, objectively assessing consumption, and interesting to understand uses and to be able to collectively respond to risky practices with adapted messages.

Preexposure Prophylaxis for Mitigating Risk of HIV Transmission During HIV Cure-Related Clinical Trials With a Treatment Interruption

Analytical treatment interruption performed during human immunodeficiency virus (HIV) cure-related clinical trials exposes sex partners of participants in these trials to a risk of HIV transmission. Preexposure prophylaxis (PrEP), which emerged in recent years as a key strategy for preventing HIV transmission, is often considered a useful tool to prevent this risk. This article supports offering PrEP to the stable sex partners of participants in these trials but also notes limitations that must be addressed. It concludes that PrEP cannot on its own eliminate the risk of secondary transmission in this context.

Pharmacokinetics of a weekly transdermal delivery system of tenofovir alafenamide in hairless rats

Tenofovir alafenamide (TAF) is a potent prodrug of tenofovir (TFV) for HIV prophylaxis, and HIV and HBV treatment. Compared to oral daily doses, transdermal administration of TAF may be more advantageous for long-term adherence by offering sustained drug delivery and reduced dosing frequency. Here, we described the plasma pharmacokinetics (PK) of an optimized once-weekly suspension transdermal delivery system (TDS) for TAF (96 mg/25 cm² of TDS) in female hairless rats. Over the study period, the TAF TDS delivered an overall low level of TAF (median: 1.43 [0.02-3.28] ng/mL) and a sustained level of the stable metabolite and parent drug, TFV. Relative to the projected exposure corresponding to six-day oral daily doses, a comparable TAF exposure but a substantially lower TFV exposure was resulted from the TAF TDS, suggesting a lower risk of TFV-associated adverse effects. TAF, TFV, and phosphorylated TFVs (TFV-monophosphate and diphosphate) were found distributed in vaginal tissue, the portal of entry for HIV during male-to-female sexual transmission. Skin adhesion and tolerance were acceptable given the animal model used. PK evaluation of the TAF TDS in hairless rats demonstrates the proof of concept that transdermal delivery can be an alternative route for a sustained, once-weekly systemic delivery of TAF.

Unexpected synergistic HIV neutralization by a triple microbicide produced in rice endosperm

Our paper provides an approach for the durable deployment of anti-HIV agents in the developing world. We developed a transgenic rice line expressing three microbicidal proteins (the HIV-neutralizing antibody 2G12 and the lectins griffithsin and cyanovirin-N). Simultaneous expression in the same plant allows the crude seed extract to be used directly as a topical microbicide cocktail, avoiding the costs of multiple downstream processes. This groundbreaking strategy is realistically the only way that microbicidal cocktails can be manufactured at a cost low enough for the developing world, where HIV prophylaxis is most in demand.

The transmission of HIV can be prevented by the application of neutralizing monoclonal antibodies and lectins. Traditional recombinant protein manufacturing platforms lack sufficient capacity and are too expensive for developing countries, which suffer the greatest disease burden. Plants offer an inexpensive and scalable alternative manufacturing platform that can produce multiple components in a single plant, which is important because multiple components are required to avoid the rapid emergence of HIV-1 strains resistant to single microbicides. Furthermore, crude extracts can be used directly for prophylaxis to avoid the massive costs of downstream processing and purification. We investigated whether rice could simultaneously produce three functional HIV-neutralizing proteins (the monoclonal antibody 2G12, and the lectins griffithsin and cyanovirin-N). Preliminary in vitro tests showed that the cocktail of three proteins bound to gp120 and achieved HIV-1 neutralization. Remarkably, when we mixed the components with crude extracts of wild-type rice endosperm, we observed enhanced binding to gp120 in vitro and synergistic neutralization when all three components were present. Extracts of transgenic plants expressing all three proteins also showed enhanced in vitro binding to gp120 and synergistic HIV-1 neutralization. Fractionation of the rice extracts suggested that the enhanced gp120 binding was dependent on rice proteins, primarily the globulin fraction. Therefore, the production of HIV-1 microbicides in rice may not only reduce costs compared to traditional platforms but may also provide functional benefits in terms of microbicidal potency.

Relevance of healthcare reimbursement data to monitor syphilis epidemic: an alternative surveillance through the national health insurance database in France, 2011-2013

OBJECTIVE

In France, surveillance of early syphilis (primary, secondary and early latent) relies on the clinician-based ResIST sentinel network. Although ResIST enables the monitoring of trends, a complete picture of the syphilis epidemic is not possible. More specifically, cases reported by this network are mostly diagnosed in free sexually transmitted infection clinics and hospitals (75% and 24%, respectively). This study aims to estimate the number and rate of diagnoses made outside these health facilities by exploring health insurance data.

METHODS

An algorithm combining healthcare reimbursements for specific diagnostic tests and recommended treatment was fitted to identify syphilis cases. Sensitivity analyses were used to validate the algorithm. Age-standardised and gender-standardised diagnosis rates were estimated using census data.

RESULTS

Between 2011 and 2013, 12 644 (7.5 cases per 100 000 inhabitants) reimbursements were made for syphilis-related diagnoses. The annual number of cases increased by 22% from 2011 (n=3771, rate=6.7/100 000) to 2013 (n=4589, rate=8.2/100 000). The rate of syphilis diagnosis increased in men from 12.9/100 000 to 16.0/100 000, while it remained steady in women at approximately 1.8/100 000. The disease burden was greatest in French overseas territories (18.1/100 000) and in the Paris area (11.7 cases/100 000).

CONCLUSION

Despite the lack of data on the number of confirmed diagnoses and information on sexual behaviour, these findings demonstrate the relevance of analysing insurance data to help monitor the syphilis epidemic in patients who visit general practitioners and non-hospital-based specialists. Thus, reimbursement database might be a relevant alternative source of continuous information on syphilis in countries with similar insurance-based healthcare systems.