Tenofovir alafenamide use in pregnant and lactating women living with HIV

Broadening access to tenofovir alafenamide for the treatment and prevention of HIV-1 infection

INTRODUCTION

Tenofovir alafenamide (TAF), a prodrug of tenofovir, achieves higher intracellular concentrations of tenofovir-diphosphate and 90% lower plasma concentrations of tenofovir compared to tenofovir disoproxil fumarate (TDF). TAF is associated with improved renal and bone safety outcomes.

AREAS COVERED

We review the efficacy and safety of TAF-containing regimens in adults and pediatrics. We highlight safety data during pregnancy, drug interactions during co-administration with tuberculosis treatment, and critical knowledge gaps to be addressed for the successful implementation of TAF in low- and middle-income countries. We performed a search on MEDLINE PubMed and conference websites for relevant articles published from January 2010 to March 2023.

EXPERT OPINION

Current evidence demonstrates that TAF has similar efficacy and tolerability, superior bone and renal safety, and higher rates of dyslipidemia and weight gain, compared with TDF. However, there are several knowledge gaps, in specific sub-populations, that require action. Emerging data suggests that TAF is safe during pregnancy, although fuller safety data to support TAF use in pregnancy is needed. Similarly, there is a lack of evidence that TAF can be used in combination with rifamycin-based tuberculosis treatment in PWH and TB. Further studies are needed to fill knowledge gaps and support the wider rollout of TAF.

Antivirals for prevention of hepatitis B virus mother-to-child transmission in human immunodeficiency virus positive pregnant women co-infected with hepatitis B virus

BACKGROUND

Hepatitis B virus (HBV)-human Immunodeficiency virus (HIV) co-infection promotes an aggressive disease course of HBV infection. In the only available non-Cochrane systematic review on antiviral therapy during pregnancy for prevention of mother-to-child transmission of HBV, none of the women studied had HBV-HIV co-infection but were either HBV- or HIV-seropositive. Treatment of HBV alone may develop HIV-strains that are resistant to non-nucleoside reverse transcriptase inhibitors. Accordingly, co-treatment of the HIV infection is recommended.

OBJECTIVES

To evaluate the benefits and harms of tenofovir-based antiviral combination regimens versus placebo, tenofovir alone, or non-tenofovir-based antiviral regimen either alone or in combination with HBV for the prevention of mother-to-child transmission of HBV in HIV-positive pregnant women co-infected with HBV.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials, MEDLINE Ovid, Embase Ovid, LILACS (Bireme), Science Citation Index Expanded (Web of Science), and Conference Proceedings Citation Index-Science (Web of Science) on 30 January 2023. We manually searched the reference lists of included trials, searched on-line trial registries, and contacted experts in the field and pharmaceutical companies for any further potential trials.

SELECTION CRITERIA

We aimed to include randomised clinical trials comparing tenofovir-based antiviral combination regimens (anti-HIV regimen with lopinavir-ritonavir therapy, or any other antiviral therapy, and two drugs with activity against HBV, specifically, tenofovir alafenamide (TAF) or tenofovir disoproxil fumarate (TDF), plus lamivudine or emtricitabine) with placebo alone, or tenofovir alone, or non-tenofovir-based antiviral regimen (zidovudine, lamivudine, telbivudine, emtricitabine, entecavir, lopinavir-ritonavir, or any other antiviral therapy) either alone or in combination with at least two other antivirals.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Primary outcomes included all-cause infant mortality, proportion of infants with serious adverse events, proportion of infants with HBV mother-to-child transmission, all-cause maternal mortality, and proportion of mothers with serious adverse events. Secondary outcomes included proportion of infants with adverse events not considered serious, proportion of mothers with detectable HBV DNA (deoxyribonucleic acid) (before delivery), maternal hepatitis B e antigen (HBeAg) to HBe-antibody seroconversion (before delivery) and maternal adverse events not considered serious. We used RevMan Web to carry out analyses and presented results, where feasible, using a random-effects model and risk ratios (RR) with 95% confidence intervals (CIs). We performed sensitivity analysis. We assessed risk of bias using predefined domains, assessed the certainty of the evidence using GRADE, controlled risk of random errors with Trial Sequential Analysis, and presented outcome results in a summary of findings table.

MAIN RESULTS

Five completed trials were included, of which four trials contributed data to one or more of the outcomes. They included a total of 533 participants randomised to tenofovir-based antiviral combination regimens (196 participants) versus control (337 participants). The control groups received non-tenofovir-based antiviral regimens either as zidovudine alone (three trials) or as a combination of zidovudine, lamivudine and lopinavir-ritonavir (five trials). None of the trials used placebo or tenofovir alone. All trials were at unclear risk of bias. Four trials used intention-to-treat analyses. In the remaining trial, two participants in the intervention group and two in the control group were lost to follow-up. However, the outcomes of these four participants were not described. Tenofovir-based antiviral combination regimen versus control We are very uncertain about the effect of a tenofovir-based antiviral combination regimen versus control on all-cause infant mortality (RR 2.24, 95% CI 0.72 to 6.96; participants = 132; trials = 1; very low-certainty evidence); proportion of infants with serious adverse events (RR 1.76, 95% CI 1.27 to 2.43; participants = 132; trials = 1; very low-certainty evidence), and proportion of mothers with serious adverse events (RR 0.90, 95% CI 0.62 to 1.32; participants = 262; trials = 2; very low-certainty evidence). No trial reported data on the proportion of infants with HBV mother-to-child transmission and all-cause maternal mortality. We are also very uncertain about the effect of tenofovir-based antiviral combination regimens versus control on the proportion of infants with adverse events not considered serious (RR 0.94, 95% CI 0.06 to 13.68; participants = 31; trials = 1; very low-certainty evidence), and proportion of mothers with detectable HBV DNA (before delivery) (RR 0.66, 95% CI 0.42 to 1.02; participants = 169; trials = 2; very low-certainty evidence). No trial reported data on maternal hepatitis B e antigen (HBeAg) to HBe-antibody seroconversion (before delivery) and maternal adverse events not considered serious. All trials received support from industry.

AUTHORS' CONCLUSIONS

We do not know what the effects of tenofovir-based antiviral combination regimens are on all-cause infant mortality, proportion of infants with serious adverse events and proportion of mothers with serious adverse events, proportion of infants with adverse events not considered serious, and proportion of mothers with detectable HBV DNA before delivery because the certainty of evidence was very low. Only one or two trials, with insufficient power, contributed data for analyses. We lack randomised clinical trials at low risk of systematic and random errors, and fully reporting all-cause infant mortality, serious adverse events and reporting on clinical and laboratory outcomes, such as infants with HBV mother-to-child transmission, all-cause maternal mortality, maternal hepatitis B e antigen (HBeAg) to HBe-antibody seroconversion before delivery and maternal adverse events not considered serious.

Pharmacokinetics of Antiretroviral Agents in Pregnant Individuals Living With HIV: Current Status and Considerations for Study Design and Interpretation

Determining the appropriate dosing regimens of antiretroviral (ARV) drugs for pregnant individuals living with HIV-1 infection is critical to maximize maternal health and prevent perinatal HIV transmission. Throughout pregnancy, pharmacokinetics (PK) of ARVs can be significantly altered due to physiological, anatomic, and metabolic changes. As such, conducting PK studies of ARVs during pregnancy is crucial to optimize dosing regimens. In this article, we summarize available data, key issues, challenges, and considerations in interpreting results of ARV PK studies in pregnant individuals. Discussion topics include the choice of the reference population (postpartum vs historical control), pregnancy trimester-dependent changes in ARV PK, effects of pregnancy on once- versus twice-daily dosing, factors to consider for ARVs that are administered with a PK booster such as ritonavir and cobicistat, and considerations when evaluating the effects of pregnancy on unbound ARV concentrations. Common approaches for the translation of the results into clinical recommendations and rationales and considerations when making clinical recommendations are summarized. Currently, limited PK data in pregnancy are available with long-acting ARVs. Collection of PK data to characterize the PK profile of long-acting ARVs is an important goal shared by many stakeholders.

Physiologic Changes During Pregnancy and Impact on Small-Molecule Drugs, Biologic (Monoclonal Antibody) Disposition, and Response

Pregnancy is a unique physiological state that results in many changes in bodily function, including cellular, metabolic, and hormonal changes. These changes can have a significant impact on the way small-molecule drugs and monoclonal antibodies (biologics) function and are metabolized, including efficacy, safety, potency, and adverse effects. In this article, we review the various physiologic changes that occur during pregnancy and their effects on drug and biologic metabolism, including changes in the coagulation, gastrointestinal, renal, endocrine, hepatic, respiratory, and cardiovascular systems. Additionally, we discuss how these changes can affect the processes of drug and biologic absorption, distribution, metabolism, and elimination (pharmacokinetics), and how drugs and biologics interact with biological systems, including mechanisms of drug action and effect (pharmacodynamics) during pregnancy, as well as the potential for drug-induced toxicity and adverse effects in the mother and developing fetus. The article also examines the implications of these changes for the use of drugs and biologics during pregnancy, including consequences of suboptimal plasma drug concentrations, effect of pregnancy on the pharmacokinetics and pharmacodynamics of biologics, and the need for careful monitoring and individualized drug dosing. Overall, this article aims to provide a comprehensive understanding of the physiologic changes during pregnancy and their effects on drug and biologic metabolism to improve the safe and effective use of drugs.

Direct antiviral agents (DAAs) and their use in pregnant women with hepatitis C (HCV)

INTRODUCTION

Direct-Acting Antiviral Agents (DAAs) provide safer, efficacious, tolerable, and curative therapy for women with hepatitis C. Their preferred safety and efficacy profile make them potential therapies for the elimination of perinatal transmission of hepatitis C virus (HCV). However, DAAs are not currently recommended for use during pregnancy due to limited pharmacokinetic and safety data.

AREAS COVERED

This review covers the different DAA drug combinations, the available data on their pharmacodynamic and pharmacokinetic properties, how the physiology in pregnancy can potentially affect DAA drug disposition, known drug-drug interactions with DAAs, and available and planned epidemiological and pharmacokinetic studies on DAA use during pregnancy. Although no large randomized clinical trials or prospective cohort studies involving DAAs have been completed in pregnancy, the currently available studies demonstrate no significant changes in pharmacokinetics, and no major safety concerns in women with hepatitis C.

EXPERT OPINION

Initial pharmacokinetic and safety data suggest that DAAs have high efficacy and a low risk of adverse events during pregnancy. As more pharmacokinetic and epidemiologic data become available, DAAs could become a preferred option for treating HCV during pregnancy and elimination of perinatal transmission of hepatitis C virus.

Pharmacological approaches to prevent vertical transmission of HIV and HBV

INTRODUCTION

Mother-to-child transmission (MTCT) is mainly responsible for the global pediatric HIV and HBV epidemic. Vertical transmission can be prevented and reduced through a series of interventions at the primary healthcare level, including extensive screening of pregnant women, administration of antivirals or immune-based treatments, counselling on type of delivery and breastfeeding.

AREAS COVERED

In this narrative review, approved therapeutic options for the treatment of pregnant women living with HIV or HBV are discussed with special focus on efficacy and safety profiles of each agent or drug class examined. The search was performed using Medline (via PubMed), Web of Science, and Google Scholar to identify studies assessing vertical transmission of both HIV and HBV.

EXPERT OPINION

Elimination of MTCT of both infections is firmly endorsed by major global commitments and the integration of tailored preventive interventions into maternal and newborn health services is of strategical importance to achieve this critical target. However, further research centered on antiviral-based and immunization trials among pregnant women is urgently needed to mitigate the risk of maternal and neonatal adverse outcomes, effectively prevent transmission to the offspring and finally eliminate the pediatric HIV and HBV epidemic, one of the key global health challenges of our time.

Pharmacokinetics of Tenofovir Alafenamide With Boosted Protease Inhibitors in Pregnant and Postpartum Women Living With HIV: Results From IMPAACT P1026s

BACKGROUND

Tenofovir alafenamide (TAF) is a key component of HIV treatment, but pharmacokinetic data supporting the use of TAF during pregnancy are limited. In this study, we report pharmacokinetic, safety, and birth outcomes for TAF 25 mg with a boosted protease inhibitor in pregnant women living with HIV.

METHODS

IMPAACT P1026s was a multicenter, nonrandomized, open-label, phase IV prospective study. Pregnant women living with HIV receiving TAF 25 mg with a boosted protease inhibitor were eligible. Intensive pharmacokinetic assessments were performed during the second and third trimesters and 6-12 weeks postpartum. Maternal and cord blood samples were collected at delivery. Infant washout samples were collected through 5-9 days postbirth. Comparisons of paired pharmacokinetic data between pregnancy and postpartum were made using geometric mean ratios (GMR) [90% confidence intervals (CIs)] and Wilcoxon signed-rank tests with P < 0.10 considered significant.

RESULTS

Twenty-nine women were enrolled from the United States (median age 31 years and weight 84.5 kg during the third trimester; 48% Black, 45% Hispanic/Latina). TAF AUCtau did not significantly differ in the second [GMR 0.62 (90% CI: 0.29 to 1.34); P = 0.46] or third trimester [GMR 0.94 (90% CI: 0.63 to 1.39); P = 0.50] vs. postpartum and were comparable with historical data in nonpregnant adults. TAF was only quantifiable in 2/25 maternal delivery samples and below the limit of quantification in all cord blood and infant washout samples, likely because of the short half-life of TAF.

CONCLUSION

TAF AUCtau did not significantly differ between pregnancy and postpartum. These findings provide reassurance as TAF use during pregnancy continues to expand.

Prediction and prevention of preterm birth in pregnant women living with HIV on antiretroviral therapy

INTRODUCTION

The rate of spontaneous preterm-birth among pregnant women living with HIV on antiretroviral therapy (ART) is 3- to 4-fold higher when compared to HIV-negative women. The pathophysiology of preterm-birth related to HIV or ART remains unknown, especially as women living with HIV are often excluded from preterm birth studies.

AREAS COVERED

This review discusses the currently available evidence on the prediction and prevention of preterm-birth in pregnant women living with HIV. A review of the literature was conducted of primary articles between 2005 and 2021 measuring the association or lack thereof between combination ART and preterm birth, as well as of other predisposing factors to preterm birth in women living with HIV, including cervical length, vaginal microbiome, and cervico-vaginal biomarkers.

EXPERT OPINION

Further research into the effect of ART exposure on preterm-birth risk is critical, and development of preterm-birth predictive tools in this population should be a priority. Vaginal progesterone supplementation deserves further investigation as a therapeutic option to prevent recurrent preterm birth in pregnant women living with HIV. The ProSPAR study, a multicenter randomized controlled trial studying progesterone supplementation in pregnant women on protease inhibitor-based regimens, has been designed but is not yet recruiting patients.

Magnitude of Drug–Drug Interactions in Special Populations

Drug–drug interactions (DDIs) are one of the most frequent causes of adverse drug reactions or loss of treatment efficacy. The risk of DDIs increases with polypharmacy and is therefore of particular concern in individuals likely to present comorbidities (i.e., elderly or obese individuals). These special populations, and the population of pregnant women, are characterized by physiological changes that can impact drug pharmacokinetics and consequently the magnitude of DDIs. This review compiles existing DDI studies in elderly, obese, and pregnant populations that include a control group without the condition of interest. The impact of physiological changes on the magnitude of DDIs was then analyzed by comparing the exposure of a medication in presence and absence of an interacting drug for the special population relative to the control population. Aging does not alter the magnitude of DDIs as the related physiological changes impact the victim and perpetrator drugs to a similar extent, regardless of their elimination pathway. Conversely, the magnitude of DDIs can be changed in obese individuals or pregnant women, as these conditions impact drugs to different extents depending on their metabolic pathway.

Treatment and prevention of viral hepatitis in pregnancy

Viral hepatitis in pregnancy may be caused by many types of viruses that cause systemic infection or target hepatocytes in their pathogenesis. Because viral hepatitis during pregnancy may represent acute or chronic infection or the reactivation of a prior infection, a high clinical suspicion, medical history review, and awareness of risk factors for the acquisition of infection are important management principles. The route of infection varies widely and ranges from fecal-oral transmission for the hepatitis A and E viruses to vertical transmission for hepatitis B, blood-borne transmission for hepatitis C, and sexual transmission for the herpes simplex virus. For this reason, the exposure details about travel, food preferences, drug use, and sexual contacts are important to elicit. Although routine prenatal screening is recommended for chronic viral hepatitis caused by hepatitis B and C, most other causes of viral hepatitis in pregnancy are detected in the setting of compatible signs and symptoms (fatigue, abdominal discomfort, jaundice, scleral icterus) or incidentally noted transaminitis on routine labs. Serologic testing is helpful for diagnosis with molecular testing as indicated to guide the management of hepatitis B and C. Preventive vaccines for hepatitis A and B with established safety of use in pregnancy are recommended for women who are at risk of acquisition. Postexposure prophylaxis for hepatitis A is a single dose of immunoglobulin and vaccination can be used if immunoglobulin G is not available. Antiviral therapy with tenofovir disoproxil fumarate is recommended as prophylaxis in pregnant women with active hepatitis B and an elevated viral load (>200,000 IU/mL) during the third trimester to prevent vertical transmission. The neonate exposed to hepatitis B at birth should receive immunoglobulin G and a monovalent birth dose vaccine within 12 hours, followed by completion of the 3-dosage vaccine series. The prevalence of hepatitis C in women of reproductive age has increased in the United States, and the role of antiviral therapy during pregnancy is of great interest. Cesarean delivery is not currently recommended for the sole purpose of reducing vertical transmission risk in pregnant women with viral hepatitis. Breastfeeding is recommended in women with hepatitis A, B, and C. New and promising prevention and treatment options for hepatitis B and C are under investigation. Investigators and regulatory authorities should ensure that these clinical trials for promising antivirals and vaccines are designed to include pregnant and lactating women.

Pregnancy Outcomes in Pregnant Women with HIV on Tenofovir Disoproxil Fumarate (TDF) Compared to Tenofovir Alafenamide (TAF)

Objective

Our objective was to assess the safety, efficacy, and pregnancy outcomes of Tenofovir Disoproxil Fumarate (TDF) compared to Tenofovir Alafenamide (TAF) use in pregnant women with HIV (PWLHIV).

Methods

This retrospective cohort study of all women who received prenatal care at a single academic center between January 1^st 2015 and June 30^th, 2020 compared outcomes in PWLHIV using TDF compared to TAF. The primary outcome was weight-gain during pregnancy. Secondary outcomes included CD4 count, viral-load, gestational age at delivery, fetal and neonatal outcomes. Outcomes were analyzed using standard statistical tests. Multivariable linear-regression analysis models accounting for potential confounders were created for primary and secondary outcomes, with beta coefficients (β) and associated 95% confidence intervals as the primary measure of effect. Statistical analysis was done with STATA 16.

Results

There were 66 women in the TDF group and 34 women in the TAF group. In the overall cohort, the median (interquartile range, IQR) gestational age at delivery for PWLHIV on TDF and TAF were 38.6 (IQR 37.5-39.4) and 38.1 (31.1-39.1) weeks respectively; and most women (85%) were Black/African American. Compared to PWLHIV on a TDF regimen, women on TAF, on average, gained over 3 kg more weight in the 3^rd trimester of pregnancy (β=3.20, 95% CI 1.64, 7.97; p=0.03). Women in the TAF arm were also more likely to have higher median CD4-count (470 cells/mm³ versus 669 cells/mm³, p=0.035) in the third trimester compared to women on TDF. There were no cases of neonatal/infant HIV or death.

Conclusion

Although TAF use was associated with more weight gain compared to TDF, both regimens appear safe and effective during pregnancy. PWLHIV should be counseled about the potential for weight gain with TAF based regimens during pregnancy.

Adherence Predictors in Pregnant Women Living with HIV on Tenofovir Alafenamide and Tenofovir Disoproxil Fumarate

BACKGROUND

Medication adherence to antiretroviral medications is critical during pregnancy in women living with HIV (WLHIV) for multiple reasons. In this study, we report medication adherence to tenofovir alafenamide (TAF) compared to tenofovir disoproxil fumarate (TDF) during pregnancy in WLHIV.

METHODS

This is a retrospective cohort study of pregnant women living with HIV aged 18-48 years who received either tenofovir alafenamide (TAF) or tenofovir disoproxil fumarate (TDF) during pregnancy. Medication adherence was assessed during each visit in all trimesters of pregnancy, and was self-reported. Demographics and outcomes were analyzed using standard statistical tests. Logistic regression analysis models accounting for potential confounders, with adjusted odds-ratios (aORs) and associated 95% confidence intervals were reported.

RESULTS

One hundred women met inclusion criteria, with thirty-four women on TAF and sixty-six women on TDF. While medication adherence was higher in women using TAF compared to TDF, with 76% adherent to TDF vs 83% adherent to TAF; p=0.282, in the 1^st trimester; 82% adherent to TDF vs 88% adherent to TAF; p=0.924, in the 2^nd trimester, and 88% adherent to TDF vs 91% adherent to TAF; p=0.176, in the 3^rd trimester of pregnancy, these differences in medication adherence were not statistically significant. In the third trimester of pregnancy, multiparous women were more likely to be adherent to TDF/TAF antiretroviral medications compared to nulliparous women - univariable odds ratio, OR 1.31, 95% CI 1.12, 1.57; p<0.05; multivariable (adjusted odds ratio, aOR 1.23, 95% CI 1.08, 1.52; p<0.05).

CONCLUSIONS

Pregnant women living with HIV on TDF and TAF achieved high adherence, but medication adherence was better in the third trimester compared to the first or second trimesters of pregnancy. These findings support the need to continually assess medication adherence during pregnancy.

An update on the physiologic changes during pregnancy and their impact on drug pharmacokinetics and pharmacogenomics

For many years, the medical community has relied in clinical practice on historic data about the physiological changes that occur during pregnancy. However, some newer studies have disputed a number of assumptions in these data for not being evidence-based or derived from large prospective cohort-studies. Accurate knowledge of these physiological changes is important for three reasons: Firstly, it facilitates correct diagnosis of diseases during pregnancy; secondly, it enables us to answer questions about the effects of medication during pregnancy and the ways in which pregnancy alters pharmacokinetic and drug-effects; and thirdly, it allows for proper modeling of physiologically-based pharmacokinetic models, which are increasingly used to predict gestation-specific changes and drug-drug interactions, as well as develop new knowledge on the mode-of-action of drugs, the mechanisms underlying their interactions, and any adverse effects following drug exposure. This paper reviews new evidence regarding the physiologic changes during pregnancy in relation to existing knowledge.

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.

Management of hepatitis B and C in special population

Chronic viral hepatitis is one of the leading causes of cirrhosis worldwide. Chronic hepatitis B is more common in the Asia-Pacific region due to the larger population and lower screening availability. Hepatitis C predominates in the west due to injection drug abuse. The discovery of (oral) direct-acting antiviral agents (DAAs) has changed the landscape of chronic hepatitis C (CHC) management. Nucleos(t)ide analogs (NUCs) have also changed the approach to the treatment of chronic hepatitis B (CHB). Oral NUCs and DAAs have excellent efficacy and patient acceptance as well as a lower risk of resistance. However, certain populations have no robust data and safety and efficacy of such oral drugs is still evolving. In this review, we provide an overview of the management of CHB and CHC in special populations, such as those with chronic kidney disease, pregnant women, healthcare workers, and those undergoing chemo- or immunosuppressive therapy.

Tenofovir, pregnancy and renal function changes in pregnant women living with HIV

This retrospective study of 100 pregnant women living with HIV [66 on tenofovir disoproxil fumarate (TDF) compared to 34 women on tenofovir alafenamide (TAF)] found no significant difference in renal function in pregnant women with HIV receiving TDF versus TAF. Our results demonstrate that, in regard to renal toxicity, both TDF and TAF appear to be safe for pregnant women living with HIV, but larger prospective cohort studies in pregnant women living with HIV are encouraged.

Optimizing Pharmacology Studies in Pregnant and Lactating Women Using Lessons From HIV: A Consensus Statement

Information on the extent of drug exposure to mothers and infants during pregnancy and lactation normally becomes available years after regulatory approval of a drug. Clinicians face knowledge gaps on drug selection and dosing in pregnancy and infant exposure during breastfeeding. Physiological changes during pregnancy often result in lower drug exposures of antiretrovirals, and in some cases a risk of reduced virologic efficacy. The International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) network and the World Health Organization (WHO)-convened Pediatric Antiretrovirals Working Group collaboratively organized a workshop of key stakeholders in June 2019 to define key standards to generate pharmacology data for antiretrovirals to be used among pregnant and lactating women; review the antiretroviral product pipeline; describe key gaps for use in low-income and middle-income countries; and identify opportunities to undertake optimal studies allowing for rapid implementation in the clinical field. We discussed ethical and regulatory principles, systemic approaches to obtaining data for pregnancy pharmacokinetic/pharmacodynamic (PK/PD) studies, control groups, optimal sampling times during pregnancy, and pharmacokinetic parameters to be considered as primary end points in pregnancy PK/PD studies. For lactation studies, the type of milk to collect, ascertainment of maternal adherence, and optimal PK methods to estimate exposure were discussed. Participants strongly recommended completion of preclinical reproductive toxicology studies prior to phase III, to allow study protocols to include pregnant women or to allow women who become pregnant after enrolment to continue in the trial. The meeting concluded by developing an algorithm for design and interpretation of results and noted that recruitment of pregnant and lactating women into clinical trials is critical.

Benefits and Risks of Antiviral Treatment during Pregnancy in Patients with Chronic Hepatitis B

Hepatitis B virus (HBV) is a main cause of chronic liver disease worldwide and can lead to severe liver diseases. The World Health Organization has planned to eliminate viral hepatitis, including hepatitis caused by HBV and hepatitis C virus, by 2030. As mother-to-child transmission (MTCT) of HBV is a main cause of chronic HBV infection, MTCT prevention is the main target to reduce the risk of chronic HBV infection and eliminate the disease. Recent clinical trials and meta-analyses found that antiviral therapy could prevent MTCT effectively in mothers with ≥200,000 IU/mL of HBV DNA, in combination with serial vaccination and hepatitis B immune globulin administration in infants. Despite the preventive role of antivirals for MTCT of HBV, there are several concerns regarding antiviral therapy with respect to the safety of the mother and fetus during pregnancy. This review summarizes the benefits and risks of antiviral treatment during pregnancy in women with chronic HBV infection.

Ethical issues in therapeutic use and research in pregnant and breastfeeding women

Pregnant or potentially pregnant women have historically been excluded from clinical trials of new medications. However, it is increasingly recognised that it is imperative to generate evidence from the population in whom the drugs are likely to be used to inform safe, evidence-based shared clinical decision making. Reluctance by researchers and regulators to perform such studies often relates to concerns about risk, particularly to the foetus. However, this must be offset against the risk of untreated disease or using a drug in pregnancy where safety, efficacy and dosing information are not known. This review summarises the historical perspective, and the ethical and legal frameworks that inform the conduct of such research, then highlights examples of innovative practice that have enabled high quality, ethical research to proceed to inform the evidence-based use of medication in pregnancy.

Long-term efficacy and safety of nucleos(t)ides analogues in patients with chronic hepatitis B

Nucleos(t)ide analogues with high barrier to resistance are regarded as the principal therapeutic option for chronic hepatitis B (CHB). Treatment with entecavir (ETV), tenofovir disoproxil (TDF) and the later released tenofovir alafenamide (TAF) is highly effective at controlling hepatitis B virus (HBV) infection and, in the vast majority of patients, is well tolerated. No significant differences in viral suppression have been described among the different regimens, although an earlier achievement in biochemical response has been suggested first under TDF and recently under TAF. High barrier to resistance NAs rarely achieve hepatitis B surface antigen sero-clearance, and therefore should be maintained life-long in most cases. This has increased concerns about treatment-related toxicity, especially in patients under TDF with additional risk factors for kidney and bone impairment. TAF has shown a better bone and kidney safety profile than TDF, although it is not yet available worldwide due to its higher cost. Emergence of adverse events should be monitored since treatment-switch to ETV/TAF seems to be effective and safe in HBV mono-infected subjects. Finally, although an effective antiviral treatment leads to a clear improvement in clinical outcome of CHB patients; the risk of developing hepatocellular carcinoma (HCC) is not completely avoided with viral suppression. Whether tenofovir-based regimens provide any additional benefit over ETV in HCC prevention remains unclear and requires further investigation.

Tenofovir Alafenamide to Prevent Perinatal Hepatitis B Transmission: A Multicenter, Prospective, Observational Study

BACKGROUND

Few safety and effectiveness results have been published regarding the administration of tenofovir alafenamide fumarate (TAF) during pregnancy for the prevention of mother-to-child transmission (MTCT) of hepatitis B virus (HBV).

METHODS

In this multicenter prospective observational study, pregnant women with HBV DNA levels higher than 200,000 IU/ml who received TAF or tenofovir disoproxil fumarate (TDF) from gestational weeks 24-35 to delivery were 1:1 enrolled and followed until postpartum month 6. Infants received immunoprophylaxis. The primary endpoint was the safety of mothers and infants. The secondary endpoint was the hepatitis B surface antigen (HBsAg)-positive rate at 7 months for infants.

RESULTS

In total, 116 and 116 mothers were enrolled, and 117 and 116 infants were born, in the TAF and TDF groups, respectively. TAF was well tolerated during a mean treatment duration of 11.0 weeks. The most common maternal adverse event was nausea (19.0%). One (0.9%), 3 (2.6%), and 9 (7.8%) mothers had abnormal alanine aminotransferase levels at delivery and at postpartum months 3 and 6, respectively. The TDF group had safety profiles that were comparable to those of the TAF group. No infants had birth defects in either group. The infants' physical and neurological development at birth and at 7 months in the TAF group were comparable with those in the TDF group. The HBsAg positive rate was 0% at 7 months in all 233 infants.

CONCLUSION

Antiviral prophylaxis with TAF was determined to be generally safe for both mothers and infants and reduced the MTCT rate to 0%.

Efficient Synthesis of Phosphonamidates through One-Pot Sequential Reactions of Phosphonites with Iodine and Amines

A one-pot sequential strategy to construct phosphonamidates has been developed by generating phosphonites in situ from arylmagnesium bromides and triethyl phosphite followed by treatment with iodine and amines. A variety of phosphonamidates were obtained with good to excellent yields at room temperature from easily available materials.

Drug-Drug Interactions with Antiretroviral Drugs in Pregnant Women Living with HIV: Are They Different from Non-Pregnant Individuals?

BACKGROUND AND OBJECTIVE

Although the separate effects of drug-drug interactions and pregnancy on antiretroviral drug pharmacokinetics have been widely studied and described, their combined effect is largely unknown. Physiological changes during pregnancy may change the extent or clinical relevance of a drug-drug interaction in a pregnant woman. This review aims to provide a detailed overview of the mechanisms, magnitude, and clinical significance of antiretroviral drug-drug interactions in pregnant women.

METHODS

We performed a literature search and selected studies that compared the magnitude of drug-drug interactions with antiretroviral drugs in pregnant vs non-pregnant women.

RESULTS

Forty-eight papers examining drug-drug interactions during pregnancy were selected, of which the majority focused on pharmacokinetic boosting. Other selected studies examined the drug-drug interactions between efavirenz and lumefantrine, efavirenz and tuberculosis drugs, etravirine and tenofovir disoproxil fumarate, atazanavir and tenofovir disoproxil, and mefloquine and nevirapine in pregnant compared to non-pregnant women. The clinical significance of antiretroviral drug-drug interactions changed during pregnancy from a minimal effect to a contra-indication. In almost all cases, the clinical significance of a drug-drug interaction was more relevant in pregnant women, owing to the combined effects of pregnancy-induced physiological changes and drug-drug interactions leading to a lower absolute drug exposure.

CONCLUSIONS

Multiple studies show that the clinical relevance of a drug-drug interaction can change during pregnancy. Unfortunately, many potential interactions have not been studied in pregnancy, which may place pregnant women living with human immunodeficiency virus and their newborns at risk.

Innovative Approaches for Pharmacology Studies in Pregnant and Lactating Women: A Viewpoint and Lessons from HIV

Medication use during pregnancy in the absence of pharmacokinetic and safety data is common, particularly for antiretrovirals, as pregnant women are not usually included in clinical trials leading to drug licensure. To date, data are typically generated through opportunistic pregnancy studies performed in the postmarketing setting, leading to a substantial time-lag between initial regulatory approval of a drug and availability of essential pregnancy-specific pharmacokinetic and safety data. During this period, health care providers lack key information on human placental transfer, fetal exposure, optimal maternal dosing in pregnancy, and maternal and fetal drug toxicity, including teratogenicity risk. We discuss new approaches that could facilitate the acquisition of these critical data earlier in the drug development process, aiding clinicians and patients in making informed decisions on drug selection and dosing during pregnancy. An integrated approach utilizing multiple novel methodologies (in vitro, ex vivo, in silico and in vivo) is needed to accelerate the availability of pharmacology data in pregnancy and lactation.

Pharmacokinetic Enhancement of HIV Antiretroviral Therapy During Pregnancy

Pharmacokinetic boosting of antiretroviral (ARV) therapies with either ritonavir or cobicistat is used to achieve target drug exposure, lower pill burden, and provide simplified dosing schedules. Several ARVs require boosting, including the integrase inhibitor elvitegravir as well as protease inhibitors such as darunavir, atazanavir, and lopinavir. The use of boosted regimens in pregnant women living with HIV has been studied for a variety of ARVs; however, a recent recommendation by the US Food and Drug Administration advised against cobicistat-boosted regimens in pregnancy due to substantially lower drug exposures observed in clinical pharmacokinetic studies. The objectives of this article are to review pharmacokinetic enhancement of ARVs with ritonavir and cobicistat during pregnancy and postpartum, describe clinical implications, and provide recommendations for future research.