Antiretroviral Therapy for Prevention of Mother-to-Child HIV Transmission

Trends in Neonatal Prophylaxis and Predictors of Combination Antiretroviral Prophylaxis in US Infants from 1990 to 2015

Postnatal antiretroviral (ARV) prophylaxis for infants born to women with HIV is a critical component of perinatal HIV transmission prevention. However, variability in prophylaxis regimens remains and consistency with guidelines has not been evaluated in the United States. We evaluated trends over time in prophylaxis regimens among 6386 HIV-exposed uninfected (HEU) infants using pooled data spanning two decades from three US-based cohorts: the Women and Infants Transmission Study (WITS, 1990-2007), Pediatric AIDS Clinical Trials Group (PACTG) 219C (1993-2007), and the PHACS Surveillance Monitoring of ART Toxicities (SMARTT) study (2007-2015). We also identified maternal and infant risk factors for use of combination prophylaxis regimens (≥2 ARVs) and examined consistency with US perinatal guidelines. We found that receipt of combination prophylaxis between 1996 and 2015 ranged from 2% to 15%, with a consistent median duration of 6 weeks. Infants whose mothers had lower CD4 T-cell counts, higher viral load (VL), no antepartum ARVs, age <20 years at delivery, and Cesarean delivery had significantly higher rates of combination prophylaxis, while infants born 2006-2010 (vs. 2011-2015), who were Hispanic or with lower maternal education levels, had significantly lower rates. Predictors for combination prophylaxis varied over time, with the strongest associations of maternal VL in later birth cohorts. While use of combination prophylaxis increased over time, only 50% of high-risk infants received such regimens in 2011-2015. In conclusion, HEU infants at higher risk of HIV acquisition are more likely to receive combination neonatal prophylaxis, consistent with US guidelines. However, substantial variability remains, and infants at higher risk often fail to receive combination prophylaxis.

HIV-1 drug resistance mutations among infants born to HIV-positive mothers in Busia, Kenya

To determine HIV-1 subtypes and transmitted HIV-1 drug-resistant mutations among HIV-1-positive children born to HIV-positive mothers in Busia County, blood samples were collected from 53 children aged between 6 weeks and 5 years in 2011. Their mothers were HIV-1 positive and on antiretroviral therapy at the time the children were born. The samples were analyzed for HIV-1 drug resistance and subtypes through sequencing of portions of the HIV-1 pol gene. The generated sequences were analyzed for subtype diversity using the REGA and BLAST subtyping tools. HIV-1 drug resistance was determined using the Stanford University HIV database. Of the 53 samples that were successfully amplified and sequenced, 69.8% (37/53) were determined to be HIV-1 subtype A, 22.6% (12/53) were subtype D, 5.6% (3/53) were subtype C, and 1.8% (1/53) were subtype A1C. The prevalence of HIV-1 drug resistance mutations of any kind was 22.6% (12/53).

Adverse drug reactions associated with antiretroviral therapy during pregnancy

INTRODUCTION

Antiretroviral (ARV) drug use during pregnancy significantly reduces mother-to-child HIV transmission, delays disease progression in the women and reduces the risk of HIV transmission to HIV-serodiscordant partners. Pregnant women are susceptible to the same adverse reactions to ARVs as nonpregnant adults as well as to specific pregnancy-related reactions. In addition, we should consider adverse pregnancy outcomes and adverse reactions in children exposed to ARVs during intrauterine life. However, studies designed to assess the safety of ARV in pregnant women are rare, usually with few participants and short follow-up periods.

AREAS COVERED

In this review, we discuss studies reporting adverse reactions to ARV drugs, including maternal toxicity, adverse pregnancy outcomes and the consequences of exposure to ARV in infants. We included results of observational studies, both prospective and retrospective, as well as randomized clinical trials, systematic reviews and meta-analyses.

EXPERT OPINION

The benefits of ARV use during pregnancy outweigh the risks of adverse reactions identified to date. More studies are needed to assess the adverse effects in the medium- and long term in children exposed to ARVs during pregnancy, as well as pregnant women using lifelong antiretroviral therapy and more recently available drugs.

Role of non-nucleoside reverse transcriptase inhibitors in treating HIV-infected children

The first-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz and nevirapine, fulfil key roles in antiretroviral therapy for HIV-infected paediatric patients, from lowering the incidence of mother-to-child transmission during pregnancy and birth to treatment throughout childhood and adolescence. Both agents have established efficacy, safety and tolerability profiles, and also offer advantages over other classes of therapy in terms of regimen simplicity and availability across different treatment settings. Although the role of NNRTIs in paediatric treatment strategies is largely determined by experience in adult patients, results of the recent phase II/III PENPACT-1 trial in infants and children aged between 30 days and 18 years have shown that there are no significant differences in 4-year virological, immunological or clinical outcomes between NNRTIs and protease inhibitors as first- and second-line agents. However, results from the IMPAACT P1060 study (cohort 2), conducted in resource-limited settings, showed that infants under 36 months unexposed to NNRTIs were significantly more likely to fail treatment when started on a nevirapine-based regimen than those on a lopinavir/ritonavir-based regimen. Unfortunately, the use of efavirenz and nevirapine in children can be limited by rapid development of high-level resistance to one or both agents, which may reduce the availability of viable treatment options, particularly in resource-limited settings. Several therapeutic strategies addressing this issue are currently under investigation, but a significant need for new NNRTI-based treatment options remains. The more recently approved NNRTI, etravirine, has demonstrated efficacy and safety benefits in HIV-1-infected, NNRTI-resistant adult patients, with a higher genetic barrier to the development of resistance relative to the first-generation NNRTIs. Another NNRTI, rilpivirine (TMC278), is approved for use in HIV-1-infected, treatment-naïve adult patients and has demonstrated an improved tolerability profile compared with efavirenz. Although available data on etravirine in children are currently limited, ongoing trials will provide important information on the potential for their use in novel paediatric treatment strategies. This review examines the role of efavirenz and nevirapine in paediatric antiretroviral therapy in children within different treatment settings. In addition, this review also outlines available clinical data on etravirine and rilpivirine in the context of how these antiretrovirals may address some of the limitations of efavirenz and nevirapine in paediatric patients.

Preventing mother to child transmission of HIV with highly active antiretroviral treatment in Tanzania--a prospective cost-effectiveness study

Recent guidelines recommend that all HIV-infected women should receive highly active antiretroviral therapy throughout pregnancy and lactation, irrespective of whether or not they need it for their own health. This strategy for prevention of mother to child transmission (PMTCT) of HIV is more effective than the well-established use of single-dose nevirapine, but it is also a more costly alternative. In this economic evaluation, we use a decision model to combine the best available clinical evidence with cost, epidemiological and behavioral data from Northern Tanzania. We find that a highly active antiretroviral therapy-based PMTCT Plus regimen is more cost effective than the current Tanzanian standard of care with single-dose nevirapine. Although PMTCT Plus is roughly 40% more expensive per pregnant woman than single-dose nevirapine, the expected health benefits are 5.2 times greater. The incremental cost effectiveness ratio of the PMTCT Plus intervention is calculated to be 4062 USD per child infection averted and 162 USD per disability adjusted life year.

Pharmacokinetics and therapeutic drug monitoring of antiretrovirals in pregnant women

Highly active antiretroviral therapy is recommended for HIV-infected pregnant women to prevent mother-to-child transmission. The specific physiological background induced by pregnancy leads to significant changes in maternal pharmacokinetics, suggesting potential variability in plasma concentrations of antiretrovirals during gestation. Therapeutic drug monitoring (TDM) of protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs) is recommended in certain situations, including pregnancy, but its systematic use in HIV-infected pregnant women remains controversial. This review provides an update of the pharmacokinetic data available for PIs and NNRTIs in pregnant women and highlights the clinical interest of systematic TDM of certain antiretroviral drugs during pregnancy, including nevirapine, nelfinavir, saquinavir, indinavir and lopinavir.

Antiretroviral resistance among HIV type 1-infected women first exposed to antiretrovirals during pregnancy: plasma versus PBMCs

Resistance-associated mutations (RAMs) in plasma samples from HIV-1-infected women who received antiretroviral (ARV) prophylaxis during pregnancy was assessed and correlated with the detection of RAMs in peripheral blood mononuclear cells (PMBCs). The study population was composed of HIV-1-infected women enrolled in a prospective cohort study in Latin America and the Caribbean (NISDI Perinatal Study) as of March 1, 2005, who were diagnosed with HIV-1 infection during the current pregnancy, who received ARVs during pregnancy for prevention of mother-to-child transmission of HIV-1, and who were followed through at least the 6-12 week postpartum visit. Plasma samples collected at enrollment during pregnancy and at 6-12 weeks postpartum were assayed for RAMs. Plasma results were compared to previously described PBMC results from the same study population. Of 819 enrolled subjects, 197 met the eligibility criteria. Nucleic acid amplification was accomplished in 123 plasma samples at enrollment or 6-12 weeks postpartum, and RAMs were detected in 22 (17.9%; 95%CI: 11.7-25.9%). Previous analyses had demonstrated detection of RAMs in PBMCs in 19 (16.1%). There was high concordance between RAMs detected in plasma and PBMC samples, with only eight discordant pairs. The prevalence of RAMs among these pregnant, HIV-1-infected women is high (15%). Rates of detection of RAMs in plasma and PBMC samples were similar.

Low Rate of Emergence of Nevirapine and Lamivudine Resistance after Post-Partum Interruption of a Triple-Drug Regimen

Introduction

Emergence of nevirapine (NVP) resistance may be a consequence of its use in monotherapy to prevent HIV mother-to-child transmission (MTCT). The aim of this study was to evaluate the emergence of strains resistant to NVP and lamivudine (3TC) after discontinuation of anti-retroviral therapy (ART) with 3TC/zidovudine (ZDV)/NVP.

Methods

Twenty pregnant women (ART-naive or pre-exposed only to ZDV), to whom 3TC/ZDV/NVP was prescribed as MTCT prophylaxis, were studied. They received ART for a median of 4 months with median viral load (VL) at labour <50 copies/ml. Samples were collected between 1 and 15 months (median: 3 months) after ART interruption. Sequence-selective real-time PCR (SPCR), which quantifies minority viral populations containing K103N, Y181C and M184V mutations, and standard genotypic sequencing were assayed.

Results

No mutations associated with resistance to 3TC or NVP were found by standard population sequencing. Analysis of K103N by SPCR showed that 35% of the patients contained ≤0.1% of viruses carrying either the AAC or AAT mutations. For Y181C mutation, 10% of the patients contained <0.5% of viruses with TGT codon change. For M184V mutation, one patient contained 6.2% of virus with GTG mutation and 13 patients (65%) contained <0.9% of mutated viruses. Four women were re-exposed to 3TC/ZDV/NVP and achieved HIV VL <50 copies/ml. No perinatal transmission occurred in any of the 22 births.

Conclusions

NVP associated with ZDV/3TC as a regimen to prevent MTCT may involve a low risk for the selection of antiretroviral-resistant strains and may not jeopardize the use of these same drugs for future treatment.

Treatment of pediatric HIV infection

HIV-infected children require a peculiar management when compared to infected adults. Antiretroviral therapy has been quite well adapted to children, but new studies are needed to answer many unsolved questions, such as when to start therapy in asymptomatic infected children. Recently, several guidelines have been updated. In this review, we compare these recommendations together with the latest studies concerning the treatment of HIV in children. A triple-drug combination therapy based either on nonnucleoside reverse transcriptase inhibitors or protease inhibitors is the recommended initial therapy. After treatment failure, a second-line therapy should be based on switching between these two regimens. Antiretroviral therapy should be managed by an expert in pediatric and adolescent HIV infection. The importance of children's adherence to therapy is a crucial point, particularly in adolescents.

HIV-1 reverse transcriptase inhibitors

Reverse transcriptase (RT) is one of the three enzymes encoded by the human immunodeficiency virus type 1 (HIV-1), the etiological agent of AIDS. Together with protease inhibitors, drugs inhibiting the RNA- and DNA-dependant DNA polymerase activity of RT are the major components of highly active antiretroviral therapy (HAART), which has dramatically reduced mortality and morbidity of people living with HIV-1/AIDS in developed countries. In this study, we focus on RT inhibitors approved by the US Food and Drugs Administration (FDA) or in phases II and III clinical trials. RT inhibitors belong to two main classes acting by distinct mechanisms. Nucleoside RT inhibitors (NRTIs) lack a 3' hydroxyl group on their ribose or ribose mimic moiety and thus act as chain terminators. Non-NRTIs bind into a hydrophobic pocket close to the polymerase active site and inhibit the chemical step of the polymerization reaction. For each class of inhibitors, we review the mechanism of action, the resistance mechanisms selected by the virus, and the side effects of the drugs. We also discuss the main perspectives for the development of new RT inhibitors.