Tenofovir and tenofovir-diphosphate concentrations during pregnancy among HIV-uninfected women using oral preexposure prophylaxis

Establishing adherence-concentration-efficacy thresholds of TDF-FTC pre-exposure prophylaxis for HIV prevention in African women: a protocol for the Women TDF-FTC Benchmark Study

Background

Oral pre-exposure prophylaxis (PrEP) using co-formulated emtricitabine (FTC) and tenofovir disoproxil fumarate (TDF) is a potent HIV prevention method for men and women, with its efficacy highly dependent on adherence. A pivotal HIV efficacy study combined with a directly observed pharmacological study defined the thresholds for HIV protection in men who have sex with men (MSM), which are the keys to PrEP promotion and development of new PrEP agents. For African women at risk for HIV and belonging to a priority group considered due to disproportionately high incident HIV infections, the variable adherence in PrEP clinical trials and the limited pharmacologic data have resulted in a lack of clarity about the PrEP adherence required for HIV protection. We propose a study to quantify the adherence-concentration-efficacy thresholds of TDF/FTC PrEP among African cisgender women to inform decisions about optimal PrEP dosing and adherence for HIV protection.

Methods

We randomized 45 low-risk HIV-uninfected African women, aged 18-30 years old, to directly observe the TDF/FTC PrEP of two, four, or seven doses per week for 8 weeks. A complementary age-matched pregnant women cohort at high risk of HIV, who will receive seven doses per week, was recruited (N = 15) with the primary aim of establishing benchmark concentrations in dried blood spots and peripheral blood mononuclear cells. Plasma, whole blood (WB), urine, hair, vaginal fluid, and vaginal tissue (non-pregnant women only) were archived for future testing. Drug concentrations were measured using methods validated for each biological matrix. Pharmacokinetic models were fitted to drug concentrations to quantify concentration-adherence thresholds. To define the drug concentrations associated with HIV protection, we applied the newly defined thresholds from the primary pharmacologic trial to the subset of women randomized to TDF/FTC or TDF in the Partners PrEP Study with the drug concentration assessed in plasma and WB samples. Multiple imputation was used to construct a data set with drug concentrations at each visit when an HIV test was performed for the entire cohort, replicating the work for MSM.

Discussion

The proposed study generated the first African women-specific TDF-PrEP adherence-concentration-efficacy thresholds essential for guiding the accurate interpretation of TDF/FTC PrEP programs and clinical trials of novel HIV prevention products using TDF/FTC as an active control.

Clinical Trial Registration

ClinicalTrials.gov, identifier (NCT05057858).

Perinatal outcomes associated with pre-exposure prophylaxis for HIV prevention during pregnancy: a systematic review and meta-analysis

Background

The World Health Organization (WHO) recommends tenofovir disoproxil fumarate (TDF)-based oral pre-exposure prophylaxis (PrEP), the dapivirine vaginal ring, and long-acting intramuscular injectable cabotegravir (CAB-LA) for HIV prevention in populations at substantial risk of HIV infection. Pregnancy is a period of elevated risk of maternal HIV infection and transmission to the infant. This systematic review and meta-analysis assessed the risk of adverse perinatal outcomes among HIV-negative pregnant women with exposure to any PrEP modality.

Methods

We conducted a systematic review by searching Medline, EMBASE, CINAHL, Global Health, the Cochrane Library, WHO ICTR, ISRCTN, PACTR, and ClinicalTrials.gov for studies published between 1 January 2000 and 29 August 2023. We included studies reporting on the association of antenatal exposure to any PrEP modality with 13 perinatal outcomes: preterm birth (PTB), very PTB, spontaneous PTB, spontaneous very PTB, low birthweight (LBW), very LBW, term LBW, preterm LBW, small for gestational age (SGA), very SGA, miscarriage, stillbirth, or neonatal death (NND). Quality assessments of included studies were performed. Fixed-effect meta-analyses were conducted to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs). The protocol is registered with PROSPERO, CRD42022339825.

Findings

Of 18,598 citations identified, 13 studies (eight randomised controlled trials (RCTs) and five cohort studies), assessing 8712 pregnant women in Africa, were included. Oral PrEP, compared to no PrEP, was not associated with PTB in meta-analyses of six RCTs (OR 0.73, 95% CI 0.43-1.26; I2 = 0.0%) or five unadjusted cohort studies (OR 0.84, 95% CI 0.69-1.03; I2 = 0.0%), but was associated with a reduced risk of PTB in three adjusted cohort studies (aOR 0.67; 95% CI 0.52-0.88, I2 = 0.0%). There was no association of oral PrEP with LBW, vLBW, SGA, or NND, compared to no PrEP. There was no association with PTB when oral TDF/emtricitabine (FTC) PrEP, oral TDF PrEP, and tenofovir vaginal gel were compared to each other. There was no association of the dapivirine vaginal ring with PTB or NND, compared to placebo or oral TDF/FTC PrEP. We found no data on CAB-LA.

Interpretation

We found no evidence of adverse perinatal outcomes associated with PrEP exposure during pregnancy. Our findings support the WHO recommendation to provide oral PrEP to women of reproductive age and pregnant women. More data is needed to assess the safety of all PrEP modalities in pregnancy.

Funding

None.

Comparing a point-of-care urine tenofovir lateral flow assay to self-reported adherence and their associations with viral load suppression among adults on antiretroviral therapy

BACKGROUND

Point-of-care (POC) lateral flow assays (LFA) to detect tenofovir (TFV) in urine have been developed to measure short-term ART adherence. Limited data exist from people living with HIV in routine care.

METHODS

Adults on TFV-containing regimens, having a routine viral load (VL) at an HIV clinic in Cape Town, South Africa were enrolled in a cross-sectional study. Patients recalled missed ART doses in the past three and 7 days and urine was tested using a POC TFV LFA. VL on the day was abstracted from medical records.

RESULTS

Among 314 participants, 293 (93%) had VL <1000 copies/mL, 20 (6%) had no TFV detected and 24 (8%) reported ≥1 missed dose in the past 3 days. Agreement between VL ≥1000 and undetectable TFV was higher compared to 3-day recall of ≥1 missed dose (Kappa 0.504 vs. 0.163, p = 0.015). The AUC to detect VL ≥1000 was 0.747 (95% CI 0.637-0.856) for undetectable TFV. This was statistically significantly better than for 7-day recall (0.571 95% CI 0.476-0.666, p = 0.040) but not for 3-day recall (0.587 95% CI 0.492-0.681, p = 0.071) of ≥1 missed dose.

CONCLUSION

In this largely virally suppressed cohort, TFV in urine had better agreement with VL than self-reported adherence and was a better predictor of viraemia on two of three self-report measures. Used in combination with VL, the POC urine TFV LFA could flag patients with viraemia in the presence of ART. Further research is needed to understand the potential application in different populations on ART, including pregnant women.

Pregnancy outcomes following self-reported and objective-measured exposure to oral preexposure prophylaxis in South Africa

OBJECTIVE

To compare pregnancy outcomes using self-reported and objective levels of intracellular tenofovir diphosphate (TFV-DP) in pregnant women using preexposure prophylaxis (PrEP).

DESIGN

We enrolled pregnant women >15 years without HIV at first antenatal care visit in an observational cohort study to compare pregnancy outcomes by PrEP use.

METHODS

Exposure defined as: any PrEP use [tenofovir disoproxil and emtricitabine (TDF/FTC]) prescription + reported taking PrEP], or objectively-measured TFV-DP in dried blood spots in PrEP-using pregnant women. The primary outcome was a composite of pregnancy loss, preterm birth (<37weeks), low birthweight (<2500 g), small for gestational age ([SGA] ≤ tenth percentile), or neonatal death. Multivariable logistic regression models evaluated individual and composite adverse outcomes by self-reported or objectively measured PrEP use adjusting for age, gestational age, gravidity and socio-economic status.

RESULTS

Between August 19 and February 23, we followed 1195 pregnant women and ascertained 1145 pregnancy outcomes (96%); 72% ( n  = 826) reported taking PrEP while pregnant, 16% did not take PrEP ( n  = 178), 12% were unconfirmed ( n  = 141). Overall, 94.5% ( n  = 1082) had singleton live births with a median birthweight of 3.2 kg [interquartile range (IQR) = 2.9-3.5], with no difference in pregnancy loss between self-reported PrEP exposed vs. unexposed [4.0 vs. 5.6%; adjusted odds ratio (aOR) = 0.65, 95% confidence interval (CI) = 0.32-1.47]. Composite adverse outcomes did not differ by reported PrEP use (20% for both groups; aOR = 1.07, 95% CI = 0.71-1.63). Comparing objective PrEP use (any TFV-DP vs. no TFV-DP or not on PrEP), adverse outcomes did not differ (aOR = 0.64, 95% CI = 0.39-1.04), nor did other outcomes including preterm birth nor SGA.

CONCLUSIONS

Pregnancy outcomes did not differ by PrEP exposure (self-reported or objective), suggesting real-world efficacy that TDF/FTC as PrEP is safe in pregnancy.

A Patient-Centered, Combination Intervention to Support Adherence to HIV Pre-exposure Prophylaxis During Pregnancy and Breastfeeding: A Randomized Pilot Study in Malawi

BACKGROUND

Daily oral pre-exposure prophylaxis (PrEP) can reduce HIV incidence in pregnant and breastfeeding women, but adherence is essential.

METHODS

We conducted a pilot randomized trial to evaluate an intervention package to enhance antenatal and postnatal PrEP use in Lilongwe, Malawi. The intervention was based on patient-centered counseling adapted from previous PrEP studies, with the option of a participant-selected adherence supporter. Participants were locally eligible for PrEP and randomized 1:1 to intervention or standard counseling (ie, control) and followed for 6 months. Participants received the intervention package or standard counseling at enrollment, 1, 3, and 6 months. Adherence was measured through plasma and intracellular tenofovir concentrations and scored using a published algorithm. Our primary outcome was retention in care with concentrations consistent with 4-7 doses/week.

RESULTS

From June to November 2020, we enrolled 200 pregnant women with the median gestational age of 26 (interquartile range: 19-33) weeks. Study retention was high at 3 months (89.5%) and 6 months (85.5%). By contrast, across the 2 time points, 32.8% of participants retained in the study had adherence scores consistent with 2-5 doses/week while 10.3% had scores consistent with daily dosing. For the composite primary end point, no substantial differences were observed between the intervention and control groups at 3 months (28.3% vs. 29.0%, probability difference: -0.7%, 95% confidence interval: -13.3%, 11.8%) or at 6 months (22.0% vs. 26.3%, probability difference: -4.3%, 95% confidence interval: -16.1%, 7.6%).

CONCLUSIONS

In this randomized trial of PrEP adherence support, retention was high, but less than one-third of participants had pharmacologically confirmed adherence of ≥4 doses/week. Future research should focus on antenatal and postnatal HIV prevention needs and their alignment across the PrEP continuum, including uptake, persistence, and adherence.

Clinical trial simulation to evaluate tenofovir disoproxil fumarate/emtricitabine HIV pre-exposure prophylaxis dosing during pregnancy

Objective

To evaluate upward-adjustment of tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC) pre-exposure prophylaxis (PrEP) dosing during pregnancy in order to maintain target plasma concentrations associated with HIV protection.

Design

Population pharmacokinetic (PK) modeling and clinical trial simulation (CTS).

Material and methods

We developed population pharmacokinetic models for TFV and FTC using data from the Partners Demonstration Project and a PK study of TDF/FTC among cisgender women by Coleman et al., and performed an in-silico simulation. Pregnancy-trimester was identified as a significant covariate on apparent clearance in the optimized final model. We simulated 1,000 pregnant individuals starting standard daily oral TDF/FTC (300 mg/200 mg) prior to pregnancy. Upon becoming pregnant, simulated patients were split into two study arms: one continuing standard-dose and the other receiving double standard-dose throughout pregnancy.

Results

Standard-dose trough TFV concentrations were significantly lower in pregnancy compared to pre-pregnancy, with 34.0%, 43.8%, and 65.1% of trough plasma concentrations below the lower bound of expected trough concentrations presumed to be the protective threshold in the 1st, 2nd, and 3rd trimesters, respectively. By comparison, in the simulated double-dose group, 10.7%, 14.4%, and 27.8% of trough concentrations fell below the estimated protective thresholds in the 1st, 2nd, and 3rd trimesters, respectively. The FTC trough plasma concentration during pregnancy was also lower than pre-pregnancy, with 45.2% of the steady-state trough concentrations below the estimated protective trough concentrations of FTC. In the pregnancy-adjusted double-dose group, 24.1% of trough plasma concentrations were lower than protective levels.

Conclusions

Our simulation shows >50% of research participants on standard dosing would have 3rd trimester trough plasma TFV concentrations below levels associated with protection. This simulation provides the quantitative basis for the design of prospective TDF/FTC studies during pregnancy to evaluate the safety and appropriateness of pregnancy-adjusted dosing.

High PrEP uptake and objective longitudinal adherence among HIV-exposed women with personal or partner plans for pregnancy in rural Uganda: A cohort study

BACKGROUND

In Uganda, fertility rates and adult HIV prevalence are high, and many women conceive with partners living with HIV. Pre-exposure prophylaxis (PrEP) reduces HIV acquisition for women and, therefore, infants. We developed the Healthy Families-PrEP intervention to support PrEP use as part of HIV prevention during periconception and pregnancy periods. We conducted a longitudinal cohort study to evaluate oral PrEP use among women participating in the intervention.

METHODS AND FINDINGS

We enrolled HIV-negative women with plans for pregnancy with a partner living, or thought to be living, with HIV (2017 to 2020) to evaluate PrEP use among women participating in the Healthy Families-PrEP intervention. Quarterly study visits through 9 months included HIV and pregnancy testing and HIV prevention counseling. PrEP was provided in electronic pillboxes, providing the primary adherence measure ("high" adherence when pillbox was opened ≥80% of days). Enrollment questionnaires assessed factors associated with PrEP use. Plasma tenofovir (TFV) and intraerythrocytic TFV-diphosphate (TFV-DP) concentrations were determined quarterly for women who acquired HIV and a randomly selected subset of those who did not; concentrations TFV ≥40 ng/mL and TFV-DP ≥600 fmol/punch were categorized as "high." Women who became pregnant were initially exited from the cohort by design; from March 2019, women with incident pregnancy remained in the study with quarterly follow-up until pregnancy outcome. Primary outcomes included (1) PrEP uptake (proportion who initiated PrEP); and (2) PrEP adherence (proportion of days with pillbox openings during the first 3 months following PrEP initiation). We used univariable and multivariable-adjusted linear regression to evaluate baseline predictors selected based on our conceptual framework of mean adherence over 3 months. We also assessed mean monthly adherence over 9 months of follow-up and during pregnancy. We enrolled 131 women with mean age 28.7 years (95% CI: 27.8 to 29.5). Ninety-seven (74%) reported a partner with HIV and 79 (60%) reported condomless sex. Most women (N = 118; 90%) initiated PrEP. Mean electronic adherence during the 3 months following initiation was 87% (95% CI: 83%, 90%). No covariates were associated with 3-month pill-taking behavior. Concentrations of plasma TFV and TFV-DP were high among 66% and 47%, 56% and 41%, and 45% and 45% at months 3, 6, and 9, respectively. We observed 53 pregnancies among 131 women (1-year cumulative incidence 53% [95% CI: 43%, 62%]) and 1 HIV-seroconversion in a non-pregnant woman. Mean pillcap adherence for PrEP users with pregnancy follow-up (N = 17) was 98% (95% CI: 97%, 99%). Study design limitations include lack of a control group.

CONCLUSIONS

Women in Uganda with PrEP indications and planning for pregnancy chose to use PrEP. By electronic pillcap, most were able to sustain high adherence to daily oral PrEP prior to and during pregnancy. Differences in adherence measures highlight challenges with adherence assessment; serial measures of TFV-DP in whole blood suggest 41% to 47% of women took sufficient periconception PrEP to prevent HIV. These data suggest that women planning for and with pregnancy should be prioritized for PrEP implementation, particularly in settings with high fertility rates and generalized HIV epidemics. Future iterations of this work should compare the outcomes to current standard of care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03832530 https://clinicaltrials.gov/ct2/show/NCT03832530?term=lynn+matthews&cond=hiv&cntry=UG&draw=2&rank=1.

The importance of assessing and addressing mental health barriers to PrEP use during pregnancy and postpartum in sub-Saharan Africa: state of the science and research priorities

Introduction

Pregnant and postpartum women (PPW) in sub‐Saharan Africa are at disproportionately high risk of HIV infection compared to non‐pregnant women. When used consistently, pre‐exposure prophylaxis (PrEP) can prevent HIV acquisition and transmission to the foetus or infant during these critical periods. Recent studies have demonstrated associations between mental health challenges (e.g. depression and traumatic stress associated with intimate partner violence) and decreased PrEP adherence and persistence, particularly among adolescents, younger women and women in the postpartum period. However, mental health is not currently a major focus of PrEP implementation research and programme planning for PPW.

Discussion

PrEP implementation programmes for PPW need to assess and address mental health barriers to consistent PrEP use to ensure effectiveness and sustainability in routine care. We highlight three key research priorities that will support PrEP adherence and persistence: (1) include mental health screening tools in PrEP implementation research with PPW, both to assess the feasibility of integrating these tools into routine antenatal and postpartum care and to ensure that limited resources are directed towards women whose symptoms may interfere most with PrEP use; (2) identify cross‐cutting, transdiagnostic psychological mechanisms that affect consistent PrEP use during these periods and can realistically be targeted with intervention in resource‐limited settings; and (3) develop/adapt and test interventions that target those underlying mechanisms, leveraging strategies from existing interventions that have successfully mitigated mental health barriers to antiretroviral therapy use among people with HIV.

Conclusions

For PPW, implementation of PrEP should be guided by a robust understanding of the unique psychological difficulties that may act as barriers to uptake, adherence and persistence (i.e. sustained adherence over time). We strongly encourage PrEP implementation research in PPW to incorporate validated mental health screening tools and ultimately treatment in routine antenatal and postnatal care, and we stress the potential public health benefits of identifying women who face mental health barriers to PrEP use.

Barriers to Oral HIV Pre-exposure Prophylaxis (PrEP) Adherence Among Pregnant and Post-partum Women from Cape Town, South Africa

Cisgender women, particularly pregnant and postpartum women in Eastern and Southern Africa, face an unacceptably high risk of HIV acquisition. Oral pre-exposure prophylaxis (PrEP) is an effective HIV prevention intervention that can reduce HIV acquisition and vertical transmission. In this qualitative study, we interviewed 21 postpartum women from Cape Town, South Africa who initiated PrEP during pregnancy and who self-reported low PrEP adherence or missed > 1 PrEP follow-up collection. We identified multiple overlapping barriers to PrEP continuation and/or adherence. Individual factors included forgetting to take PrEP daily, being away from home when PrEP should be taken, anticipated stigma and limited disclosure of PrEP use. Women also reported pill-related factors such as side effects and having to take PrEP in addition to other tablets during pregnancy and the postpartum period. Facility-related barriers included logistics around PrEP collection especially when not in antenatal care, as well as transport and financial barriers.

Tenofovir Diphosphate in Dried Blood Spots in Pregnant and Postpartum Women With HIV in Kenya: A Novel Approach to Measuring Peripartum Adherence

BACKGROUND

Adherence to antiretroviral therapy (ART) among pregnant and postpartum women with HIV (PWLWH) is critical to promote maternal health and prevent HIV transmission. Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is an objective assessment of cumulative ART adherence that has not been fully assessed in PWLWH.

SETTING

Southwestern Kenya.

METHODS

PWLWH receiving tenofovir disoproxil fumarate-based ART from 24 health facilities provided DBS samples at 3 time points [pregnancy/early postpartum (PP), 6 months PP, and 9-12 months PP]. Thresholds for daily adherence were defined as TFV-DP in DBS ≥650 fmol/punch in pregnancy and ≥950 PP. Descriptive analysis is presented. Cluster adjusted χ2 and t-tests were used to test for association with clinical and demographic factors.

RESULTS

A total of 419 DBS samples were collected from 150 PWLWH. Median TFV-DP in DBS was lowest, 552 fmol/punch [interquartile range (IQR), 395-759] in pregnancy and declined over time [914 (IQR, 644-1176) fmol/punch; early PP; 838 (IQR, 613-1063) fmol/punch 6 months PP; and 785 (IQR, 510-1009) fmol/punch 9-12 months; P < 0.001]. Only 42% of samples in pregnancy and 38.5% of samples in PP met thresholds for daily adherence. Clinical or demographic factors were not associated with suboptimal adherence levels.

CONCLUSION

Cumulative ART exposure in PWLWH, quantified by TFV-DP in DBS, demonstrated a stepwise decrease (ie, adherence) PP. Most women demonstrated less than daily adherence throughout the peripartum period. Use of TFV-DP in DBS as a measure of cumulative ART adherence could help optimize health outcomes in PWLWH and their infants.

"I had Made the Decision, and No One was Going to Stop Me" -Facilitators of PrEP Adherence During Pregnancy and Postpartum in Cape Town, South Africa

PrEP is safe and effective but requires adherence during potential HIV exposure, yet the facilitators of long-term maternal adherence are not well understood. We conducted semi-structured interviews with 25 postpartum women who reported high adherence (PrEP use ≥ 25 days in last 30-days and never missed a PrEP prescription in pregnancy/postpartum period) within a PrEP service for pregnant and postpartum women. A thematic approach guided an iterative process of coding and analysis. Themes identified as drivers of optimal PrEP use were HIV risk perception, mainly because of partner’s behaviors and unknown serostatus, and a strong desire to have a baby free of HIV. Reported disclosure of PrEP use facilitated PrEP adherence. Women discussed having partner and family support, which included reminders to take PrEP daily. Primary barriers were anticipated or experienced stigma, overcome through education of partners and family about PrEP. Pregnant women experienced transient side-effects, but found ways to continue, including taking PrEP at night. PrEP programs for pregnant and postpartum women should integrate strategies to assist women with realistic appraisals of risk and teach skills for disclosure and securing support from significant others.

Safety review of tenofovir disoproxil fumarate/emtricitabine pre-exposure prophylaxis for pregnant women at risk of HIV infection

Introduction: Pregnancy is a period of elevated HIV risk in high-burden settings, motivating the need for prevention tools that are both safe for use and effective during pregnancy. Oral pre-exposure prophylaxis (PrEP) containing tenofovir disoproxil fumarate (TDF) is recommended by the World Health Organization, including for pregnant and postpartum women at substantial risk of HIV infection. Although TDF use during pregnancy appears generally safe, data on PrEP use during pregnancy remain limited.Areas covered: We provide an overview of the clinical pharmacology and efficacy of daily TDF-based PrEP and summarize current evidence on the safety of PrEP use by pregnant HIV-uninfected women. We synthesize relevant studies assessing pregnancy outcomes among pregnant women who are living with HIV (WLHIV) and using TDF-based therapy. Finally, we make comparison to the safety profiles of other emerging HIV prevention options.Expert opinion: The current evidence indicates that TDF/FTC PrEP use is not associated with increased risk of adverse pregnancy and early infant growth outcomes. While safety data are generally reassuring, there is need for continued accrual of data on growth and pregnancy outcomes in PrEP research, implementation projects, and controlled pharmacokinetic studies to support current evidence and to understand concentration-efficacy relationship in pregnant women.

Frequency and Predictors of Tenofovir-diphosphate Detection Among Young Kenyan Women in a Real-world Pre-exposure Prophylaxis Implementation Program

In a pre-exposure prophylaxis program for Kenyan women, we detected tenofovir-diphosphate in 61% (125/201) of randomly selected dried blood spots collected at the first follow-up visit. Tenofovir-diphosphate was detected more frequently among women who had partners living with human immunodeficiency virus, who were not pregnant, and who were ≥24 years.

Detectable HIV RNA in late pregnancy associated with low tenofovir hair levels at time of delivery among women living with HIV in the United States

OBJECTIVE

We evaluated peripartum tenofovir (TFV) exposure via hair measures among women living with HIV in the United States.

DESIGN

Observational cohort study.

METHODS

Hair samples were collected at or shortly after childbirth among mothers enrolled in the Surveillance Monitoring for Antiretroviral Therapy Toxicities Study of the Pediatric HIV/AIDS Cohort Study between 6/2014 and 7/2016. Among mothers receiving TFV disoproxil fumarate (TDF)-based regimens during pregnancy, TFV hair concentrations were analyzed using liquid chromatography/tandem mass spectrometry. Weight-normalized TFV concentrations were log10 transformed. Multivariable linear regression assessed correlates of TFV concentrations.

RESULTS

Overall, 121 mothers on TDF-based antiretroviral therapy during pregnancy had hair specimens tested for TFV concentrations and were included in the analysis. Median age at delivery was 31 years [interquartile range (IQR) 26-36]; 71% self-identified as non-Hispanic black, and 10% had unsuppressed viral loads in late pregnancy (HIV RNA ≥ 400 copies/ml). Median time from birth to hair collection was 3 days (IQR 1-14) and median TFV hair concentration was 0.02 ng/mg (IQR 0.01-0.04). In multivariable models, an unsuppressed viral load in late pregnancy was associated with 80% lower adjusted mean peripartum TFV concentrations than pregnancies with viral suppression (95% confidence interval: -90% to -59%, P < 0.001). Use of TDF only in the first trimester and attaining high school graduation were also associated with lower TFV hair concentrations.

CONCLUSION

Unsuppressed viral load during late pregnancy was strongly associated with lower maternal TFV hair concentrations at birth, though viremia was rare. Efforts to improve maternal virological outcomes and eliminate vertical HIV transmission could incorporate drug exposure monitoring using hair or other metrics.

Tenofovir diphosphate concentrations in dried blood spots from pregnant and postpartum adolescent and young women receiving daily observed pre-exposure prophylaxis in sub-Saharan Africa

Background

Intracellular tenofovir diphosphate (TFV-DP) concentration in dried blood spots (DBSs) is used to monitor cumulative pre-exposure prophylaxis (PrEP) adherence. We evaluated TFV-DP in DBSs following daily oral PrEP (emtricitabine 200 mg/tenofovir diphosphate 300 mg) among pregnant and postpartum adolescent girls and young women (AGYW).

Methods

Directly observed PrEP was administered for 12 weeks in a pregnancy (14–24 weeks’ gestation, n = 20) and postpartum (6–12 weeks postpartum, n = 20) group of AGYW aged 16–24 years in sub-Saharan Africa. Weekly DBS TFV-DP was measured by validated liquid chromatography–tandem mass spectrometry assay. Week 12 TFV-DP distributions were compared between groups with Wilcoxon test. Population pharmacokinetic models were fit to estimate steady-state concentrations and create benchmarks for adherence categories. Baseline correlates of TFV-DP were evaluated.

Results

Median age was 20 (IQR, 19–22) years. Of 3360 doses, 3352 (>99%) were directly observed. TFV-DP median (IQR) half-life was 10 (7–12) days in pregnancy and 17 (14–21) days postpartum, with steady state achieved by 5 and 8 weeks, respectively. Observed median (IQR) steady-state TFV-DP was 965 fmol/punch (691–1166) in pregnancy versus 1406 fmol/punch (1053–1859) postpartum (P = .006). Modeled median steady-state TFV-DP was 881 fmol/punch (667–1105) in pregnancy versus 1438 fmol/punch (1178–1919) postpartum. In pooled analysis, baseline creatinine clearance was associated with observed TFV-DP concentrations.

Conclusions

TFV-DP in African AGYW was approximately one-third lower in pregnancy than postpartum. These Population-specific benchmarks can be used to guide PrEP adherence support in pregnant/postpartum African women.

Clinical Trials Registration

NCT03386578

Monoclonal antibodies with subnanomolar affinity to tenofovir for monitoring adherence to antiretroviral therapies: from hapten synthesis to prototype development

Approximately 32 million people have died of HIV infection since the beginning of the outbreak, and 38 million are currently infected. Among strategies adopted by the Joint United Nations Programme on HIV/AIDS to end the AIDS global epidemic, the treatment, diagnosis, and viral suppression of the infected subjects are considered crucial for HIV prevention and transmission. Although several antiretroviral (ARV) drugs are successfully used to manage HIV infection, their efficacy strictly relies on perfect adherence to the therapy, which is seldom achieved. Patient supervision, especially in HIV-endemic, low-resource settings, requires rapid, easy-to-use, and affordable analytical tools, such as the enzyme-linked immunosorbent assay (ELISA) and especially the lateral flow immunoassay (LFIA). In this work, high-affinity monoclonal antibodies were generated to develop ELISA and LFIA prototypes for monitoring tenofovir (TFV), an ARV drug present in several HIV treatments. TFV was functionalized by inserting a carboxylated C5-linker at the phosphonic group of the molecule, and the synthetic derivative was conjugated to proteins for mice immunization. Through a rigorous screening strategy of hybridoma supernatants, a panel of monoclonal antibodies strongly binding to TFV was obtained. Following antibody characterization for affinity and selectivity by competitive ELISA, a LFIA prototype was developed and tentatively applied to determine TFV in simulated urine. The point-of-care test showed ultra-high detectability (the visual limit of detection was 2.5 nM, 1.4 ng mL^-1), excellent selectivity, and limited proneness to matrix interference, thus potentially making this rapid method a valuable tool for the on-site assessment of patient adherence to ARV therapy.

Pharmacokinetics of oral tenofovir disoproxil fumarate in pregnancy and lactation: a systematic review

BACKGROUND

Tenofovir disoproxil fumarate (TDF), the oral prodrug of tenofovir (TFV), is advocated in pregnancy for prevention of mother-to-child transmission (PMCT) with failure of hepatitis B immunoglobulin and vaccination. The pharmacokinetics of TDF monotherapy for PMCT-HBV is important if deployment is to emulate the success of multiple antiretrovirals (ARVs) for PMCT-HIV in resource-constrained settings.

METHODS

This systematic review followed a protocol and is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA) guidelines. We included studies that enrolled pregnant women who received oral TDF therapy as monotherapy or in combination with other ARVs: irrespective of the reason for receiving the drug (for example, HIV, HBV or pre-exposure prophylaxis); and reported pharmacokinetics.

RESULTS

The area under the concentration-time curve (AUC), maximum plasma concentrations (C_max) and last measurable plasma concentration (C_last) of TFV were decreased in the second and third trimester compared with first trimester or post-partum. In none of the manuscripts was the non-pregnant HBV threshold of C_max of 300 ng/ml reached, but the 50% effective concentration (EC₅₀) of TFV is lower for treatment of HBV compared with HIV. The TFV concentration in breastfed infants was 0.03% of the recommended infant dose.

CONCLUSIONS

Most knowledge of pharmacokinetics of TFV in pregnancy results from studies on HIV involving multiple ARVs. Increased TFV clearance occurred in the second and third trimester when optimal TFV concentrations are required to maximize suppression of HBV in the window before birth. Dose or duration adjustments will be better conceptualized with concurrent analysis of the pharmacokinetics of TFV monotherapy and hepatitis B pharmacodynamics in pregnancy.

Effect of Pregnancy and Concomitant Antiretrovirals on the Pharmacokinetics of Tenofovir in Women With HIV Receiving Tenofovir Disoproxil Fumarate-Based Antiretroviral Therapy Versus Women With HBV Receiving Tenofovir Disoproxil Fumarate Monotherapy

Tenofovir disoproxil fumarate (TDF) is recommended as part of antiretroviral therapy (ART) for pregnant women with HIV and as monotherapy for pregnant women with hepatitis B virus (HBV) monoinfection at high risk of transmitting infection to their infants. Tenofovir (TFV) plasma exposures are reduced during pregnancy; however, concomitant antiretrovirals and the viral infection itself can also influence TFV pharmacokinetics. Our aim was to compare TFV pharmacokinetics in pregnant women receiving TDF‐based ART, with or without a ritonavir‐boosted protease inhibitor (r/PI), to pregnant women with HBV receiving TDF monotherapy. Non‐r/PI regimens were primarily integrase strand transfer inhibitors or nonnucleoside reverse transcriptase inhibitor–based regimens. Data were combined from a pharmacokinetic study of pregnant women with HIV on ART (PANNA), and a study assessing TFV pharmacokinetics in pregnant women with HBV (iTAP). A total of 196 pregnant women, 59 with HIV (32 receiving r/PIs) and 137 with HBV monoinfection were included. Intraindividual TFV area under the plasma concentration–time curve from time 0 to 24 hours was 25%, 26%, and 21% lower during the third trimester compared to 1 month postpartum in women with HIV using TDF and an r/PI or TDF and non‐r/PI and women with HBV receiving TDF monotherapy, respectively. TFV area under the plasma concentration–time curve from time 0 to 24 hours was similar in pregnant women receiving non‐r/PI to pregnant women with HBV receiving TDF monotherapy (1.84 vs 1.86 µg • h/mL); however, pregnant women receiving TDF with an r/PI had higher exposures (2.41 µg • h/mL; P < .01). Pregnancy reduces TFV exposure and the relative size was not impacted by concomitant antiretroviral drugs or viral infection, but a drug‐drug interaction between TDF and r/PI remains during pregnancy, leading to higher exposures than those on TDF and non‐r/PI or TDF monotherapy.

Prevention of mother-to-child transmission of hepatitis B virus: protocol for a one-arm, open-label intervention study to estimate the optimal timing of tenofovir in pregnancy

INTRODUCTION

Hepatitis B virus (HBV) remains a public health threat and the main route of transmission is from mother to child (MTCT). Tenofovir disoproxil fumarate (TDF) treatment can reduce MTCT of HBV although the optimal timing to attain undetectable HBV DNA concentrations at delivery is unknown. This protocol describes the procedures following early initiation of maternal TDF prior to 20 weeks gestation to determine efficacy, safety and feasibility of this approach in a limited-resource setting.

METHODS AND ANALYSES

One hundred and seventy pregnant women from the Thailand-Myanmar border between 12 and <20 weeks gestational age will be enrolled into a one-arm, open-label, TDF treatment study with cessation of TDF 1 month after delivery. Sampling occurs monthly prenatal, at birth and at 1, 2, 4 and 6 months post partum. Measurement of tenofovir concentrations in maternal and cord plasma is anticipated in 10-15 women who have detectable HBV DNA at delivery and matched to 20-30 women with no detectable HBV DNA. Infant HBsAg status will be determined at 2 months of age and HBV DNA confirmed in HBsAg positive cases. Adverse events including risk of flare and adherence, based on pill count and questionnaire, will be monitored. Infants will receive HBV vaccinations at birth, 2, 4 and 6 months and hepatitis B immunoglobulin at birth if the mother is hepatitis B e antigen positive. Infant growth and neurodevelopment at 6 months will be compared with established local norms.

ETHICS AND DISSEMINATION

This study has ethical approval by the Ethics Committee of the Faculty of Tropical Medicine, Mahidol University (FTM ECF-019-06), Johns Hopkins University (IRB no: 00007432), Chiang Mai University (FAM-2559-04227), Oxford Tropical Research Ethics Committee (OxTREC Reference: 49-16) and by the local Tak Community Advisory Board (TCAB-02/REV/2016). The article will be published as an open-access publication.

TRIAL REGISTRATION NUMBER

NCT02995005, Pre-results.

Defining gaps in pre-exposure prophylaxis delivery for pregnant and post-partum women in high-burden settings using an implementation science framework

Pregnancy is a high-risk period for HIV acquisition in African women, and pregnant women who become acutely infected with HIV account for up to a third of vertical HIV transmission cases in African settings. To protect women and eliminate vertical transmission, WHO recommends offering oral pre-exposure prophylaxis (PrEP) based on tenofovir to HIV-negative pregnant and post-partum women with a substantial risk of HIV acquisition. PrEP implementation for pregnant and post-partum women lags behind implementation for other high-risk populations. Unique considerations for PrEP implementation arise during pregnancy and post partum, including the integration of provider training with clinical delivery and monitoring of PrEP exposure and outcomes within existing maternal health systems, yet scarce implementation data are available to generate evidence in this context.

Tenofovir alafenamide use in pregnant and lactating women living with HIV

Introduction: Tenofovir alafenamide (TAF)-containing fixed-dose drug combinations (FDCs) are increasingly being used in managing pregnant women living with HIV. However, TAF is not currently recommended during pregnancy due to limited pharmacokinetic and safety data. TAF, a newer nucleotide phosphonamidate prodrug of tenofovir (TFV), achieves high levels of tenofovir-diphosphate in lymphoid cells and hepatocytes, and 90% lower systemic concentrations of TFV compared to tenofovir disoproxil fumarate (TDF), thereby maximizing TAF's antiviral efficacy, potency and clinical safety.Areas covered: This review discusses the currently available information on the pharmacology of TAF in pregnant women living with HIV. Pharmacokinetic studies with TAF during pregnancy have yielded varying results compared to postpartum, but TAF exposures during pregnancy have been within the range of those typically observed in non-pregnant adults. The efficacy and safety of TAF in treatment-naïve pregnant women living with HIV is currently being evaluated in the VESTED study, a phase-III NIH randomized clinical trial.Expert opinion: Initial pregnancy data suggest that TAF-based FDCs have high efficacy and low risk of adverse effects during pregnancy. TAF is likely to become part of first-line regimens for use in pregnant women living with HIV once additional pregnancy data from phase III trials are available.

A Comparison of Plasma Efavirenz and Tenofovir, Dried Blood Spot Tenofovir-Diphosphate, and Self-Reported Adherence to Predict Virologic Suppression Among South African Women

BACKGROUND

Tenofovir-diphosphate (TFV-DP) in dried blood spots (DBS) is an objective long-term adherence measure, but data are limited on its ability to predict virologic suppression (VS) in people on antiretroviral (ARV) treatment. There are also no data comparing DBS TFV-DP with plasma ARV concentrations as predictors of VS.

METHODS

Women who were on a first-line regimen of tenofovir, emtricitabine, and efavirenz (EFV) were enrolled in a cross-sectional study. Plasma EFV and tenofovir (TFV), DBS TFV-DP assays, and 30-day self-reported adherence were evaluated as predictors of VS (<50 copies/mL) with the area under the curve of receiver operating characteristics and logistic regression.

RESULTS

We enrolled 137 women; mean age of 33 years; median 4 years on antiretroviral therapy; 88 (64%) had VS. In receiver operating characteristics analyses: DBS TFV-DP [0.926 (95% CI: 0.876 to 0.976)] had a higher area under the curve than plasma TFV [0.864 (0.797 to 0.932); P = 0.006], whereas plasma EFV [0.903 (0.839-0.967)] was not significantly different from DBS TFV-DP (P = 0.138) or plasma TFV (P = 0.140); all ARV assays performed better than self-report. The association of TFV-DP in DBS with VS strengthened with increasing concentrations [reference <350 fmol/punch: 350-699 fmol/punch aOR 37 (8-178); 700-1249 fmol/punch aOR 47 (13-175); ≥1250 fmol/punch aOR 175 (20-1539)]. "White coat adherence" (defined as DBS TFV-DP <350 fmol/punch with detectable plasma TFV) was only detected in 4 women.

CONCLUSIONS

Plasma EFV, TFV, and DBS TFV-DP were all strong predictors of VS. EFV or TFV assays have potential for development as point-of-care assays for use as objective adherence measures in resource-limited settings.

Antenatal Intracellular Concentrations of Tenofovir Diphosphate and Emtricitabine Triphosphate and Associations Between Tenofovir Diphosphate and Severe Adverse Pregnancy Outcomes: IMPAACT-PROMISE (1077BF) Trial

BACKGROUND

In the Promoting Maternal and Infant Survival Everywhere (PROMISE) trial, tenofovir disoproxil fumarate (TDF) use was associated with moderate or severe adverse pregnancy/neonatal outcomes. This study characterized tenofovir diphosphate (TFV-DP) and emtricitabine triphosphate (FTC-TP) concentrations in dried blood spots (DBS) and assessed association between severe adverse pregnancy/neonatal outcomes and TFV-DP concentration.

METHODS

Retrospective case-control study of PROMISE trial arm-C women randomized to receive TDF, FTC, and ritonavir-boosted lopinavir (LPV/r), who took at least 1 dose of TDF + FTC and had week-4 postrandomization DBS drawn before delivery. Cases, defined as severe adverse pregnancy/neonatal outcomes (very preterm delivery before 34 weeks of gestation, stillbirth ≥20 weeks of gestation, or infant death before 14 days-of-age), were matched to controls (1:2 ratio) by site and gestational age at entry. Week 4 and week 8 DBS samples were assayed for TFV-DP and FTC-TP by liquid chromatography and tandem mass spectrometry. Associations were tested using Wilcoxon rank test and conditional logistic regression.

RESULTS

Of 447 PROMISE arm-C women, 33 met case definitions, and overall, 22 cases and 44 controls were analyzed. Median (interquartile range) concentrations of TFV-DP at weeks 4 and 8 were 706 (375-1023) fmol/punch and 806 (414-1265) fmol/punch, respectively. Odds ratio (95% confidence interval) for severe adverse pregnancy/neonatal outcome with natural log of TFV-DP concentrations as the predictor were 1.27 (0.74 to 2.18) and 1.74 (0.66 to 4.60) at weeks 4 and 8, respectively. Median (interquartile range) concentrations of FTC-TP at weeks 4 and 8 were 0.27 (0.05-0.36) pmol/punch and 0.29 (0.05-0.40) pmol/punch, respectively.

CONCLUSIONS

TFV-DP concentrations in DBS appeared not to be associated with severe adverse pregnancy/neonatal outcomes, although sample size was limited.

Pre-exposure prophylaxis uptake and early continuation among pregnant and post-partum women within maternal and child health clinics in Kenya: results from an implementation programme

BACKGROUND

Pregnant women in settings with high HIV prevalence are at increased risk of HIV acquisition and subsequent vertical transmission. We implemented and evaluated a novel programme to provide pre-exposure prophylaxis (PrEP) in maternal and child health clinics in Kenya.

METHODS

In collaboration with Kisumu County Department of Health, we integrated PrEP delivery within 16 maternal and child health clinics in Kisumu County (Kenya). Women and girls older than 15 years seeking maternal and child health services who tested HIV negative at that visit or within a month and were willing to receive PrEP counselling were interviewed to assess for HIV behavioural risk factors and offered PrEP. Correlates of PrEP initiation and continuation were assessed using Poisson regression in univariate and multivariate analyses. Potential correlates included in our analyses were age, marital status, marriage type, whether pregnant or post partum, gestational age (if pregnant), and HIV risk factors in the previous 6 months. Reasons for the decision to discontinue after having decided to initiate PrEP were evaluated. Women who initiated PrEP were followed up 1 month, 3 months, and 6 months after initiation.

FINDINGS

Between Nov 20, 2017, and June 13, 2018, 9376 pregnant and post-partum women were assessed for behavioural risk factors and willingness to initiate PrEP. Overall, 2030 (21·7%) initiated PrEP, and 2027 had the status of their partner captured (153 [79·3%] of 193 women with partners living with HIV, 1178 [37·2%] of 3165 women with partners of unknown HIV status, and 696 [11·6%] of 5997 women with HIV-negative partners). Predictors of PrEP initiation in the multivariate analysis were: being younger than 24 years (adjusted prevalence ratio 1·14, 95% CI 1·02-1·28); having a partner living with HIV (6·96, 5·46-8·89) or of unknown HIV status (3·08, 2·50-3·81); gestational age of less than 26 weeks (1·22, 1·02-1·47); having been diagnosed or treated for a sexually transmitted infection (1·57, 1·20-2·06); having been forced to have sex (1·82, 1·38-2·42); having experienced intimate partner violence during the previous 6 months (1·65, 1·10-2·48); having shared needles while engaging in injection drug use (2·43, 1·69-3·50); and recurrent use of post-exposure prophylaxis (1·96, 1·36-2·82). Overall, 786 (38·7%) of 2030 women who initiated PrEP continued use after the first month, with 104 (68·0%) of 153 women who had a partner living with HIV continuing use. Having a partner living with HIV was the only predictor of PrEP continuation at 1 month in the multivariable model (1·98, 1·54-2·55). Frequent reasons for discontinuation were side effects and low HIV risk perception. No incident HIV infection was reported among women on PrEP.

INTERPRETATION

Many women attending maternal and child health clinics had risk factors for HIV and elected to use PrEP, indicating that routinely accessed maternal and child health clinics can be an effective platform for PrEP delivery for young women. As PrEP awareness rises, PrEP provision in routine clinical settings such as maternal and child health facilities might contribute to decreased HIV incidence among young women.

FUNDING

US Department of State.

Reciprocal Modulation of Antiretroviral Drug and Steroid Receptor Function In Vitro

Millions of women are exposed simultaneously to antiretroviral drugs (ARVs) and progestin-based hormonal contraceptives. Yet the reciprocal modulation by ARVs and progestins of their intracellular functions is relatively unexplored. We investigated the effects of tenofovir disoproxil fumarate (TDF) and dapivirine (DPV), alone and in the presence of select steroids and progestins, on cell viability, steroid-regulated immunomodulatory gene expression, activation of steroid receptors, and anti-HIV-1 activity in vitro Both TDF and DPV modulated the transcriptional efficacy of a glucocorticoid agonist via the glucocorticoid receptor (GR) in the U2OS cell line. In TZM-bl cells, DPV induced the expression of the proinflammatory interleukin 8 (IL-8) gene while TDF significantly increased medroxyprogesterone acetate (MPA)-induced expression of the anti-inflammatory glucocorticoid-induced leucine zipper (GILZ) gene. However, peripheral blood mononuclear cell (PBMC) and ectocervical explant tissue viability and gene expression results, along with TZM-bl HIV-1 infection data, are reassuring and suggest that TDF and DPV, in combination with dexamethasone (DEX) or MPA, do not reciprocally modulate key biological effects in primary cells and tissue. We show for the first time that TDF induces progestogen-independent activation of the progesterone receptor (PR) in a cell line. The ability of TDF and DPV to influence GR and PR activity suggests that their use may be associated with steroid receptor-mediated off-target effects. This, together with cell line and individual donor gene expression responses in the primary models, raises concerns that reciprocal modulation may cause side effects in a cell- and donor-specific manner in vivo.

Transgender women on oral HIV pre-exposure prophylaxis have significantly lower tenofovir and emtricitabine concentrations when also taking oestrogen when compared to cisgender men

INTRODUCTION

Oral HIV Pre-Exposure Prophylaxis (PrEP) with tenofovir (TFV) disoproxil fumarate (TDF)/emtricitabine (FTC) is highly effective. Transgender women (TGW) have increased HIV risk, but have been underrepresented in trials. For TGW on oestrogens for gender-affirming hormone treatment (GAHT), TDF/FTC-oestrogen interactions may negatively affect HIV prevention or gender-affirming goals. Our aim was to evaluate any pharmacokinetic drug-drug interaction between GAHT and TDF/FTC.

METHODS

We performed a pharmacokinetic study, in an urban outpatient setting in 2016 to 2018, of the effects of GAHT on TFV, FTC and the active forms TFV diphosphate (TFV-DP) and FTC triphosphate (FTC-TP) in eight TGW and eight cisgender men (CGM). At screening, participants were HIV negative. TGW were to maintain their GAHT regimens and have plasma oestradiol concentrations >100 pg/mL. Under direct observation, participants took oral TDF/FTC daily for seven days. At the last dose, blood was collected pre-dose, one, two, four, six, eight and twenty-four hours, and colon biopsies were collected at 24 hours to measure drug concentration. TGW versus CGM concentration comparisons used non-parametric tests. Blood and colon tissue were also obtained to assess kinase expression.

RESULTS

Plasma TFV and FTC C24 (trough) concentrations in TGW were lower by 32% (p = 0.010) and 32% (p = 0.038) respectively, when compared to CGM. Plasma TFV and FTC 24-hr area under the concentration-time curve in TGW trended toward and was significantly lower by 27% (p = 0.065) and 24% (p = 0.028) respectively. Peak plasma TFV and FTC concentrations, as well as all other pharmacokinetic measures, were not statistically significant when comparing TGW to CGM. Oestradiol concentrations were not different comparing before and after TDF/FTC dosing. Plasma oestrogen concentration, renal function (estimated creatinine clearance and glomerular filtration rate), and TFV and FTC plasma concentrations (trough and area under the concentration-time curve) were all correlated.

CONCLUSIONS

GAHT modestly reduces both TFV and FTC plasma concentrations. In TGW taking GAHT, it is unknown if this reduction will impact the HIV protective efficacy of a daily PrEP regimen. However, the combination of an on demand (2 + 1 + 1) PrEP regimen and GAHT may result in concentrations too low for reliable prevention of HIV infection.