Modeling dynamic interactions between pre-exposure prophylaxis interventions & treatment programs: predicting HIV transmission & resistance.
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SUBMITTER: Supervie V
PROVIDER: S-EPMC3240958 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Pre-exposure prophylaxis (PrEP) has emerged as a promising strategy for preventing the transmission of HIV. Although only one formulation is currently approved for PrEP, research into both new compounds and new delivery systems for PrEP regimens offer intriguing challenges from the perspective of pharmacokinetic and pharmacodynamic modeling. This review aims to provide an overview the current modeling landscape for HIV PrEP, focused on PK/PD and QSP models relating to antiretroviral agents. Both current PrEP treatments and new compounds that show promise as PrEP agents are highlighted, as well as models of uncommon administration routes, predictions based on models of mechanism of action and viral dynamics, and issues related to adherence to therapy. The spread of human immunodeficiency virus (HIV) remains one of the foremost global health concerns. In the absence of a vaccine, other prophylactic strategies have been developed to prevent HIV transmission. One approach, known as pre-exposure prophylaxis (PrEP), allows HIV-negative individuals who are at high risk of exposure to the virus, be it through an HIV-positive sexual partner or through the shared use of drug injection equipment, to substantially reduce the risk of developing an HIV infection. PrEP is a relatively recent approach to combating the HIV epidemic, with the only currently approved treatment being Truvada, a daily oral antiretroviral (ARV) therapy initially indicated in the treatment of active HIV-1 infections, but approved for HIV PrEP in 2012. Although PrEP therapy has consistently demonstrated high efficacy in preventing HIV infection, this efficacy is dependent on patient adherence to the prescribed treatment regimen. This can present a significant problem in low- and middle-income countries, which may lack the infrastructure to provide sufficient access to PrEP medication to maintain daily dosing regimens. Furthermore, while the conventional approach has generally been to advocate for continuous administration akin to regimens used for viral suppression in infected patients, there has been some discussion of whether a better treatment paradigm might be to push for PrEP therapy primarily during those known periods of heightened exposure risk, while relying on post-exposure prophylaxis regimens to prevent infection after unanticipated exposures during low-risk periods. These considerations have led to a push for the development of long-duration and on-demand PrEP formulations, including subdermal and subcutaneous implants, slow-release intramuscular depot injections, vaginal and rectal antimicrobial gels, and intravaginal rings and dissolving films. PrEP therapy is a quickly evolving field, with a variety of antiretroviral compounds and formulations under investigation. This review aims to report on notable drugs and formulations from a pharmacokinetic/pharmacodynamic (PK/PD) modeling perspective. Given the nature of PrEP as a preventive therapy designed for long-term use, clinical trials for PrEP therapies can last for months or even years, particularly in the case of long-duration formulations. Furthermore, in contrast to antiretroviral trials in infected patients, pharmacodynamic endpoints in PrEP therapies are difficult to quantify, as the primary endpoint for efficacy is generally the rate of seroconversion. Computational modeling approaches offer flexible and powerful tools to provide insight into drug behavior in clinical settings, and can ultimately reduce the time, expense, and patient burden incurred in the development of PrEP therapies.
| S-EPMC7005100 | biostudies-literature
Project description:There are currently several ongoing or planned trials evaluating the efficacy of pre-exposure prophylaxis (PrEP) as a preventative approach to reducing the transmission of HIV. PrEP may prove ineffective, demonstrate partial efficacy, or show high efficacy and have the potential to reduce HIV infection in a significant way. However, in addition to the trial results, it is important that issues related to delivery, implementation and further research are also discussed. As a part of the ongoing discussion, in June 2009, the Bill & Melinda Gates Foundation sponsored a Planning for PrEP conference with stakeholders to review expected trial results, outline responsible educational approaches, and develop potential delivery and implementation strategies. The conference reinforced the need for continued and sustained dialogue to identify where PrEP implementation may fit best within an integrated HIV prevention package. This paper identifies the key action points that emerged from the Planning for PrEP meeting.
| S-EPMC2914050 | biostudies-literature
Project description:BackgroundInterventions to promote HIV pre-exposure prophylaxis (PrEP) among Black sexual minority men (BSMM) are especially important, given the disproportionate HIV incidence and relatively low uptake of PrEP among BSMM.MethodsWe conducted a systematic literature review to identify the characteristics of interventions between 2016 and 2021 promoting PrEP use among BSMM. We synthesized these studies based on sample size, location, the use of peer-based delivery, and key intervention targets.ResultsOf the starting total 198 articles, 10 were included in the final review, with the majority of included studies being randomized controlled trials. We identified providing PrEP access, PrEP counseling, HIV and PrEP education, linkage to general health care, and peer-based support as key successful intervention components. The starkest difference between interventions with and without demonstrated PrEP improvements was the outcome: all interventions focused on PrEP initiation led to large improvements, but those focused on PrEP adherence did not. No other factors demonstrated distinct differences between successful and unsuccessful interventions.ConclusionWe identified notable differences in intervention efficacy between PrEP initiation and PrEP adherence outcomes; PrEP adherence is necessary for optimal HIV prevention. Future interventions promoting and measuring PrEP adherence, with a focus on cultural competence and peer components, are recommended.
| S-EPMC8871743 | biostudies-literature
Project description:Rectal pre-exposure prophylaxis (PrEP) will be a critical component of HIV prevention products due to the prevalence of unprotected receptive anal intercourse among men who have sex with men and heterosexual couples. Given the biological considerations of this compartment and the complexity of HIV infection, design of a successful rectal microbicide product faces a number of challenges. Important information is being compiled to begin to address deficits in knowledge toward design of rectal PrEP products for men and women. Aspects of formulation development and preclinical and clinical evaluation of rectal products studied to date are summarized in this review. This article is based on a presentation at the "Product Development Workshop 2013: HIV and Multipurpose Prevention Technologies," held in Arlington, Virginia on February 21-22, 2013. It forms part of a special supplement to Antiviral Research.
| S-EPMC3896093 | biostudies-literature
Project description:As pre-exposure prophylaxis (PrEP) effectiveness is strongly linked to adherence, we sought to determine if certain self-report measures could be used to inform objective PrEP adherence. We studied participants from the TAPIR study (a multicenter randomized study of daily text messages to support adherence to PrEP In At-Risk), a 48-week randomized controlled trial of HIV-uninfected men who have sex with men (MSM) randomized to receive text message to support adherence versus standard of care. Self-reported medication adherence was assessed using several validated measures modified for PrEP. Objective PrEP adherence was determined through dried blood spot (DBS) measurement of intracellular tenofovir diphosphate (TFV-DP) and emtricitabine triphosphate (FTC-TP). A summary of adherence was estimated using responses to the seven adherence items at weeks 12 and 48 using confirmatory factor analysis. Correlations between self-report questions and drug concentrations were estimated with Pearson's correlations for continuous outcomes and point-biserial correlations for dichotomous outcomes. Receiver operating characteristic (ROC) analyses were conducted to assess the performance of self-report measures in predicting protective or perfect TFV-DP concentrations. Of the 369 participants who completed week 12 or 48 visits, the mean age was 35 (standard deviation 9 years), with 79% White, 12% Black, and 29% Hispanic. Correlations between self-report measures of adherence (both individual items and the adherence factor) and quantifiable FTC-TP and continuous TFV-DP concentrations showed that all self-report measures were significantly associated with these objective measures. Compared to a summary measure of self-reported adherence, the 4-week percent taken question medication recall was the only self-report item similarly or more strongly associated with recent adherence and long-term protective and perfect adherence at weeks 12 and 48. ROC analysis also showed that 4-week percent taken question had a reasonable AUC (0.798 at week 12 and 0.758 at week 48) in predicting protective TFV-DP concentrations. All single-item self-report questions assessing PrEP adherence were significantly associated with biomarker quantification, with the 4-week percent taken question performing best. Therefore, in the absence of drug concentration measurements, a 4-week self-report percent taken question may be a good single-item measure of PrEP adherence.
| S-EPMC6624646 | biostudies-literature
Project description:The efficacy of HIV pre-exposure prophylaxis (PrEP) relies on adherence and may also depend on the route of HIV acquisition. Clinical studies of systemic tenofovir disoproxil fumarate (TDF) PrEP revealed reduced efficacy in women compared to men with similar degrees of adherence. To select the most effective PrEP strategies, preclinical studies are critically needed to establish correlations between drug concentrations (pharmacokinetics [PK]) and protective efficacy (pharmacodynamics [PD]). We utilized an in vivo preclinical model to perform a PK-PD analysis of systemic TDF PrEP for vaginal HIV acquisition. TDF PrEP prevented vaginal HIV acquisition in a dose-dependent manner. PK-PD modeling of tenofovir (TFV) in plasma, female reproductive tract tissue, cervicovaginal lavage fluid and its intracellular metabolite (TFV diphosphate) revealed that TDF PrEP efficacy was best described by plasma TFV levels. When administered at 50 mg/kg, TDF achieved plasma TFV concentrations (370 ng/ml) that closely mimicked those observed in humans and demonstrated the same risk reduction (70%) previously attained in women with high adherence. This PK-PD model mimics the human condition and can be applied to other PrEP approaches and routes of HIV acquisition, accelerating clinical implementation of the most efficacious PrEP strategies.
| S-EPMC5286499 | biostudies-literature
Project description:There is increasing evidence that the use of antiretroviral agents (ARVs) can be a safe and effective means of preventing HIV infection. In fact, a combination of ARVs, tenofovir-emtricitabine, was recently approved by the US Food and Drug Administration (FDA) for use as "pre-exposure prophylaxis"(PrEP), and the US Centers for Disease Control and other regulatory authorities have issued guidance concerning PrEP use. Clinicians and policy makers are now faced with questions about the appropriateness of prescribing ARVs to healthy persons who are at risk of becoming infected with HIV, and those at risk of being infected must decide whether to use PrEP. In addition, researcher stakeholders must grapple with determining whether and how PrEP should be included in future HIV prevention research. In addressing such issues, it is important that their ethical dimensions are identified. When using PrEP, 2 broad ethical domains are of special relevance: well-being and justice. Ethical issues related to well-being include safety, parameters of use, risk behaviors, resistance, stigma, and diversion. Those related to justice include access and competing priorities. In research involving PrEP, ethical issues include determining the appropriate control arm and whether PrEP should be included as a part of the prevention package provided to all at risk participants. Although PrEP could play an important role in HIV prevention, understanding and addressing the related ethical issues is critical to its safe, effective, and appropriate use in practice and future research.
| S-EPMC3728665 | biostudies-other
Project description:BackgroundMultiple prevention measures have the possibility of impacting HIV incidence in South Korea, including early diagnosis, early treatment, and pre-exposure prophylaxis (PrEP). We investigated how each of these interventions could impact the local HIV epidemic, especially among men who have sex with men (MSM), who have become the major risk group in South Korea. A mathematical model was used to estimate the effects of each these interventions on the HIV epidemic in South Korea over the next 40 years, as compared to the current situation.MethodsWe constructed a mathematical model of HIV infection among MSM in South Korea, dividing the MSM population into seven groups, and simulated the effects of early antiretroviral therapy (ART), early diagnosis, PrEP, and combination interventions on the incidence and prevalence of HIV infection, as compared to the current situation that would be expected without any new prevention measures.ResultsOverall, the model suggested that the most effective prevention measure would be PrEP. Even though PrEP effectiveness could be lessened by increased unsafe sex behavior, PrEP use was still more beneficial than the current situation. In the model, early diagnosis of HIV infection was also effectively decreased HIV incidence. However, early ART did not show considerable effectiveness. As expected, it would be most effective if all interventions (PrEP, early diagnosis and early treatment) were implemented together.ConclusionsThis model suggests that PrEP and early diagnosis could be a very effective way to reduce HIV incidence in South Korea among MSM.
| S-EPMC3963840 | biostudies-literature
Project description:ObjectivesThe objective was to perform a survey-based service evaluation of our telephone PrEP clinic (Tele-PrEP), which was instituted during the COVID-19 pandemic, to inform future service delivery.MethodsWe administered parallel, web-based, anonymous surveys to PrEP-users who had a Tele-PrEP appointment between 13.11.2020 and 17.12.2020 and all healthcare professionals (HCPs) conducting Tele-PrEP clinics. We used descriptive statistics to summarise demographic and qualitative data, and thematically categorised free text responses using the Framework for a Systems Approach to Healthcare Delivery.Results62/117 (53%) PrEP-users and 8/9 (89%) HCPs completed the surveys. Tele-PrEP was rated 'excellent' or 'good' by 61/62 (98%) PrEP-users. All HCPs felt that Tele-PrEP allowed them to assess patients safely and confidently. 10/62 (16%) PrEP-users and 1 (11%) HCP expressed a preference for face-to-face care. Using the Framework for a Systems Approach to Healthcare Delivery we identified key areas important to respondents who highlighted the rapid changes as a result of COVID-19, which required an increase in dedicated resources. HCPs valued teamwork, support/supervision and convenience in achieving quality care for the patient, who in turn, valued convenient, holistic and individualised management to meet their sexual healthcare needs.ConclusionTele-PrEP is feasible and acceptable. While most respondents rated the service highly, others identified a need/preference for face-to-face appointments.
| S-EPMC9189322 | biostudies-literature
Project description:There are too many new HIV infections globally with 1.8 million persons infected in 2016 alone. Pre-exposure prophylaxis (PrEP) holds potential to decrease new infections and is synergistic with efforts currently in place to achieve an end to the AIDS epidemic in Sub-Saharan African, but uptake is limited. Given its novelty, assessing the beliefs and attitudes of healthcare professionals and members of the community towards HIV transmission and PrEP will be helpful to inform implementation efforts. Study was a random survey of 201 community members and 51 healthcare providers, carried out at multiple community sites in Huye district, Southern Province, Rwanda and at Kigali University Teaching Hospital (KUTH). The study findings are that there are still misconceptions about HIV in the community with some respondents believing that HIV is due to punishment from God (5.4%), poverty (3.0%), smoking cigarettes (1.0%), drinking alcohol (2.0%), punishment from ancestors (1.0%) and witchcraft (1.5%), and that its transmission is by mosquito bites (10.9%), sharing food or drinks with a HIV infected person (6.5%) or as a result of carelessness (47.8%). More than 50% of respondents from both groups had insufficient knowledge regarding PrEP, but expressed some interest in PrEP (82.6% of the respondents from the community and 86.5% of the health workers). However, some healthcare workers felt that promotion of safe sex practices (74.5%), HIV testing and treating HIV infected patients (60.8%) would work better than PrEP to decrease new HIV infections. Barriers to PrEP implementation included perceived stigma, delayed access to prevention services at the health facilities while personal-level concerns included lack of family support, reluctance to take a medication daily and fear of being perceived as having HIV. This study showed that health care workers and community members are willing to utilize PrEP in Rwanda, but many challenges exist including limited knowledge about PrEP, stigma, provider and system level service delivery barriers at health facilities among others. More studies are needed to assess ways of addressing and /or eliminating these barriers.
| S-EPMC6261021 | biostudies-literature