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

Brief Report: Group-Based Trajectory Modeling to Determine Long-Term HIV Viral Load Trends Among Children With HIV in Kenya

BACKGROUND

Identifying determinants of longitudinal HIV viral load (VL) trajectories using group-based trajectory modeling (GBTM) can inform clinical strategies and mechanisms of nonadherence among children.

METHODS

Children under 12 months old who were newly diagnosed with HIV were enrolled in the Optimizing Pediatric HIV therapy cohort (NCT00428116) from 2007 to 2010. Children initiated antiretroviral therapy at enrollment, and VL was assessed every 3 months for 24 months post-antiretroviral therapy and every 6 months thereafter up to 8 years old. VL trajectory groups were defined using GBTM. Fisher's exact and Kruskal-Wallis tests were used to determine the correlates of each trajectory group compared with the sustained-low VL group.

RESULTS

Five VL trajectory groups were identified among 89 children with 522 VL visits from 6 to 24 months: sustained-low (63% of children), sustained-very-high (16%), sustained-high (9%), low-to-high (7%), and high-with-periods-of-low (6%). Children in the sustained-high group were more frequently on a first-line protease inhibitor (PI)-based regimen (63% vs 38%; P = 0.03) and had younger caregivers (median: 22 vs 28 years; P = 0.02). Among 54 children with 560 VL visits followed from 48 to 96 months, 5 trajectory groups were identified: sustained-low (74%), mid-range (4%), periods-of-low (7%), high-to-low (7%), and sustained-high (7%). Those in the high-to-low group had younger caregivers (21 vs 29 years; P = 0.01).

CONCLUSIONS

GBTM identified unique VL patterns among children with unsuppressed VL. Caregiver and regimen-related characteristics were associated with patterns of nonsuppression. Younger caregivers may benefit from tailored counseling to help them support child antiretroviral therapy adherence. Palatable regimens are necessary for viral suppression among children with HIV.

Virologic Response to Early Antiretroviral Therapy in HIV-infected Infants: Evaluation After 2 Years of Treatment in the Pediacam Study, Cameroon

INTRODUCTION

Little is known about virologic responses to early antiretroviral therapy (ART) in HIV-infected infants in resource-limited settings. We estimated the probability of achieving viral suppression within 2 years of ART initiation and investigated the factors associated with success.

METHODS

We analyzed all 190 infants from the Cameroon Pediacam who initiated ART by 12 months of age. The main outcome measure was viral suppression (<1000 copies/mL) on at least 1 occasion; the other outcome measures considered were viral suppression (<400 copies/mL) on at least 1 occasion and confirmed viral suppression (both thresholds) on 2 consecutive occasions. We used competing-risks regression for a time-to-event analysis to estimate the cumulative incidence of outcomes and univariate and multivariate models to identify risk factors.

RESULTS

During the first 24 months of ART, 20.0% (38) of the infants died, giving a mortality rate of 11.9 deaths per 100 infant-years (95% confidence interval: 8.1-15.7). The probability of achieving a viral load below 1000 or 400 copies/mL was 80.0% (69.0-81.0) and 78.0% (66.0-79.0), respectively. The probability of virologic suppression (with these 2 thresholds) on 2 consecutive occasions was 67.0% (56.0-70.0) and 60.0% (49.0-64.0), respectively. Virologic success was associated with not having missed any doses of treatment before the visit, but not with socioeconomic and living conditions.

CONCLUSION

Many early treated children failed to achieve virologic suppression, likely due to a combination of adherence difficulties, drug dosing and viral resistance, which highlights the need for routine viral load monitoring. The high infant mortality despite early ART initiation needs to be addressed in sub-Saharan countries.

Acylcarnitine Profiles in HIV-Exposed, Uninfected Neonates in the United States

We sought to determine the prevalence of abnormal acylcarnitine profiles (ACP) in HIV-exposed uninfected (HEU) newborns and to explore the association of abnormal ACP with clinical laboratory outcomes and antiretroviral drug exposures. Clinically, ACP are used to assess for fatty acid oxidation (FAO) dysfunction and normal FAO is necessary for optimal fetal/neonatal growth and development. We analyzed serum ACP in 522 HEU neonates enrolled in the Surveillance Monitoring for ART Toxicities (SMARTT) study of the Pediatric HIV/AIDS Cohort Study (PHACS) and evaluated the associations of abnormal ACP with in utero exposure to combination antiretroviral therapy (cART) in logistic regression models, adjusting for maternal demographic, disease, and behavioral characteristics. We evaluated the associations of abnormal ACP with laboratory parameters and measures of neurodevelopment and growth. Of 522 neonates, 89 (17%) had abnormal ACP. In adjusted analyses, in utero exposure to a protease inhibitor (PI) was associated with higher odds of having an abnormal ACP [adjusted odds ratio (aOR) = 2.35, 95% CI: 0.96, 5.76, p = 0.06] with marginal significance while exposure to a nonnucleoside reverse transcriptase inhibitor (NNRTI) was associated with lower odds (aOR = 0.23, 95% CI: 0.07, 0.80, p = 0.02). Mean ALT levels were slightly higher in those with abnormal ACP, but no differences in lactate, glucose, or CPK were observed. ACP status was not associated with neurodevelopment at 1 year or growth at 2 and 3 years of age. Abnormal ACP in HEU neonates are associated with exposure to PI-containing as opposed to NNRTI-containing antiretroviral (ARV) regimens but are not associated with serious postnatal clinical problems. Further studies are needed to determine the long-term health implications of abnormal acylcarnitine metabolism at birth in HEU children.

Long-term virological outcome in children on antiretroviral therapy in the UK and Ireland

Objective:

To assess factors at the start of antiretroviral therapy (ART) associated with long-term virological response in children.

Design:

Multicentre national cohort.

Methods:

Factors associated with viral load below 400 copies/ml by 12 months and virologic failure among children starting 3/4-drug ART in the UK/Irish Collaborative HIV Paediatric Study were assessed using Poisson models.

Results:

Nine hundred and ninety-seven children started ART at a median age of 7.7 years (inter-quartile range 2.9–11.7), 251 (25%) below 3 years: 411 (41%) with efavirenz and two nucleoside reverse transcriptase inhibitors (EFV + 2NRTIs), 264 (26%) with nevirapine and two NRTIs (NVP + 2NRTIs), 119 (12%; 106 NVP, 13 EFV) with non-nucleoside reverse transcriptase inhibitor and three NRTIs (NNRTI + 3NRTIs), and 203 (20%) with boosted protease inhibitor-based regimens. Median follow-up after ART initiation was 5.7 (3.0–8.8) years. Viral load was less than 400 copies/ml by 12 months in 92% [95% confidence interval (CI) 91–94%] of the children. Time to suppression was similar across regimens (P = 0.10), but faster over calendar time, with older age and lower baseline viral load. Three hundred and thirty-nine (34%) children experienced virological failure. Although progression to failure varied by regimen (P < 0.001) and was fastest for NVP + 2NRTIs regimens, risk after 2 years on therapy was similar for EFV + 2NRTIs and NVP + 2NRTIs, and lowest for NNRTI + 3NRTIs regimens (P-interaction = 0.03). Older age, earlier calendar periods and maternal ART exposure were associated with increased failure risk. Early treatment discontinuation for toxicity occurred more frequently for NVP-based regimens, but 5-year cumulative incidence was similar: 6.1% (95% CI 3.9–8.9%) NVP, 8.3% (95% CI 5.6–11.6) EFV, and 9.8% (95% CI 5.7–15.3%) protease inhibitor-based regimens (P = 0.48).

Conclusion:

Viral load suppression by 12 months was high with all regimens. NVP + 3NRTIs regimens were particularly efficacious in the longer term and may be a good alternative to protease inhibitor-based ART in young children.

Antiretroviral treatment in HIV-1 infected pediatric patients: focus on efavirenz

Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI), used for the treatment of human immunodeficiency virus (HIV)-1 infection. Approved by the US Food and Drug Administration in 1998, its indication was recently extended to include children as young as 3 months of age. The World Health Organization and many national guidelines consider efavirenz to be the preferred NNRTI for first-line treatment of children over the age of 3 years. Clinical outcomes of patients on three-drug antiretroviral regimens which include efavirenz are as good as or better than those for patients on all other currently approved HIV medications. Efavirenz is dosed once daily and has pediatric-friendly formulations. It is usually well tolerated, with central nervous system side effects being of greatest concern. Efavirenz increases the risk of neural tube defects in nonhuman primates and therefore its use during the first trimester of pregnancy is limited in some settings. With minimal interactions with antituberculous drugs, efavirenz is preferred for use among patients with HIV/tuberculosis coinfection. Efavirenz can be rendered inactive by a single point mutation in the reverse transcriptase enzyme. Newer NNRTI drugs such as etravirine, not yet approved for use in children under the age of 6 years, may maintain their activity following development of efavirenz resistance. This review highlights key points from the existing literature regarding the use of efavirenz in children and suggests directions for future investigation.

Short communication: high rates of thymidine analogue mutations and dual-class resistance among HIV-infected Ugandan children failing first-line antiretroviral therapy

HIV-infected children are at high risk of acquiring drug-resistant viruses, which is of particular concern in settings where antiretroviral drug options are limited. We aimed to assess resistance patterns and predict viral drug susceptibility among children with first-line antiretroviral therapy (ART) failure in Uganda. A cross-sectional analysis of children switching ART regimens due to first-line failure was performed at three clinical sites in Uganda. HIV-RNA determination and genotypic resistance testing on all specimens with HIV-RNA >1,000 copies/ml were performed. Major drug resistance mutations were scored using the 2011 International Antiviral Society-USA list. The Stanford algorithm was used to predict drug susceptibility. At the time of switch, 44 genotypic resistance tests were available for 50 children. All children harbored virus with nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance [95% confidence interval (CI) 92-100%] and NRTI resistance was present in 98% (95% CI 88-100%). Forty-six percent (95% CI 30-61%) of children harbored ≥2 thymidine analog mutations. M184V was identified as the only NRTI mutation in 27% (95% CI 15-43%). HIV susceptibility to NRTIs, with the exception of tenofovir, was reduced in ≥60% of children. Ugandan children experiencing first-line ART failure in our study harbored high rates of dual-class and accumulated HIV drug resistance. Methods to prevent treatment failure, including adequate pediatric formulations and alternative second-line treatment options, are urgently needed.

A yeast chemical genetic screen identifies inhibitors of human telomerase

Telomerase comprises a reverse transcriptase and an internal RNA template that maintains telomeres in many eukaryotes, and it is a well-validated cancer target. However, there is a dearth of small molecules with efficacy against human telomerase in vivo. We developed a surrogate yeast high-throughput assay to identify human telomerase inhibitors. The reversibility of growth arrest induced by active human telomerase was assessed against a library of 678 compounds preselected for bioactivity in S. cerevisiae. Four of eight compounds identified reproducibly restored growth to strains expressing active human telomerase, and three of these four compounds also specifically inhibited purified human telomerase in vitro. These compounds represent probes for human telomerase function, and potential entry points for development of lead compounds against telomerase-positive cancers.

Etravirine: a guide to its use in treatment-experienced pediatric patients with HIV-1 infection in the US

Etravirine (Intelence®), an oral next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI), is approved for the treatment of HIV-1 infection in treatment-experienced patients. In the US, the approved use of etravirine in patients who have evidence of viral replication and harbor HIV-1 strains resistant to other antiretroviral agents has recently been expanded to include pediatric patients aged ≥ 6 to <18 years. At 24 and 48 weeks in an open-label trial, etravirine 5.2 mg/kg twice daily (maximum dosage 200 mg twice daily) plus an optimized background therapy regimen achieved complete viral response (defined as HIV-1 RNA <50 copies/mL) in approximately half of treatment-experienced children and adolescents with HIV-1 infection and evidence of viral replication, and had an acceptable tolerability profile.