A randomized, open-label study of the safety and efficacy of switching stavudine or zidovudine to tenofovir disoproxil fumarate in HIV-1-infected children with virologic suppression

First Pharmacokinetic Data of Tenofovir Alafenamide Fumarate and Tenofovir With Dolutegravir or Boosted Protease Inhibitors in African Children: A Substudy of the CHAPAS-4 Trial

BACKGROUND

We evaluated the pharmacokinetics of tenofovir alafenamide fumarate (TAF) and tenofovir in a subset of African children enrolled in the CHAPAS-4 trial.

METHODS

Children aged 3-15 years with human immunodeficiency virus infection failing first-line antiretroviral therapy were randomized to emtricitabine/TAF versus standard-of-care nucleoside reverse transcriptase inhibitor combination, plus dolutegravir, atazanavir/ritonavir, darunavir/ritonavir, or lopinavir/ritonavir. Daily emtricitabine/TAF was dosed according to World Health Organization (WHO)-recommended weight bands: 120/15 mg in children weighing 14 to <25 kg and 200/25 mg in those weighing ≥25 kg. At steady state, 8-9 blood samples were taken to construct pharmacokinetic curves. Geometric mean (GM) area under the concentration-time curve (AUC) and the maximum concentration (Cmax) were calculated for TAF and tenofovir and compared to reference exposures in adults.

RESULTS

Pharmacokinetic results from 104 children taking TAF were analyzed. GM (coefficient of variation [CV%]) TAF AUClast when combined with dolutegravir (n = 18), darunavir/ritonavir (n = 34), or lopinavir/ritonavir (n = 20) were 284.5 (79), 232.0 (61), and 210.2 (98) ng*hour/mL, respectively, and were comparable to adult reference values. When combined with atazanavir/ritonavir (n = 32), TAF AUClast increased to 511.4 (68) ng*hour/mL. For each combination, tenofovir GM (CV%) AUCtau and Cmax remained below reference values in adults taking 25 mg TAF with a boosted protease inhibitors.

CONCLUSIONS

In children, TAF combined with boosted PIs or dolutegravir and dosed according to WHO-recommended weight bands provides TAF and tenofovir concentrations previously demonstrated to be well tolerated and effective in adults. These data provide the first evidence for use of these combinations in African children.

CLINICAL TRIALS REGISTRATION

ISRCTN22964075.

Drug toxicity in the proximal tubule: new models, methods and mechanisms

The proximal tubule (PT) reabsorbs most of the glomerular filtrate and plays an important role in the uptake, metabolism and excretion of xenobiotics. Some therapeutic drugs are harmful to the PT, and resulting nephrotoxicity is thought to be responsible for approximately 1 in 6 of cases of children hospitalized with acute kidney injury (AKI). Clinically, PT dysfunction leads to urinary wasting of important solutes normally reabsorbed by this nephron segment, leading to systemic complications such as bone demineralization and a clinical scenario known as the renal Fanconi syndrome (RFS). While PT defects can be diagnosed using a combination of blood and urine markers, including urinary excretion of low molecular weight proteins (LMWP), standardized definitions of what constitutes clinically significant toxicity are lacking, and identifying which patients will go on to develop progressive loss of kidney function remains a major challenge. In addition, much of our understanding of cellular mechanisms of drug toxicity is still limited, partly due to the constraints of available cell and animal models. However, advances in new and more sophisticated in vitro models of the PT, along with the application of high-content analytical methods that can provide readouts more relevant to the clinical manifestations of nephrotoxicity, are beginning to extend our knowledge. Such technical progress should help in discovering new biomarkers that can better detect nephrotoxicity earlier and predict its long-term consequences, and herald a new era of more personalized medicine.

Bone outcomes in virally suppressed youth with HIV switching to tenofovir disoproxil fumarate

Background

Tenofovir disoproxil fumarate (TDF) is included in first-line antiretroviral treatment (ART) for adolescents living with HIV (ALWH). Associated toxicities remain a concern.

Objective

We evaluated bone and renal safety outcomes in virologically suppressed South African ALWH after switching to TDF.

Method

We recruited virally suppressed (< 100 copies/mL) adolescents, aged 15-20 years, who switched from an abacavir (ABC)-based to a TDF-based efavirenz regimen. Bone mass and renal function were assessed at Week 0 and at Week 24 after the switch to TDF using dual-energy X-ray absorptiometry (DXA) and serum renal markers. A change in the lumbar spine (LS) and the whole-body less head (WBLH) bone mineral density (BMD) Z-scores and the estimated glomerular filtration rate (eGFR) between the two measures were compared (paired t-tests) and stratified by sex.

Results

Fifty participants (48% male), with a median duration of prior ART of 11.4 years, were enrolled. Among 47 participants with 24-week DXA results, 15 (32%) had either no change or a decreased LS-BMD after the switch, with a mean change of -1.6%. Overall, more female participants experienced this outcome: 58% versus 4%, P < 0.0001. The mean change (standard deviation) in the LS-Z-score was -0.03 (0.25) and in the WBLH-Z-score was 0.02 (0.24). A decrease in the eGFR from 132.2 to 120.4 was observed (P = 0.0003); however, the levels remained clinically acceptable.

Conclusion

South African ALWH switching from abacavir to TDF-based ART experienced statistically significant decreases in eGFR but not in LS and WBLH BMD. Female ALWH were more likely to experience a decrease in LS-BMD and may require closer monitoring.

Viral load care of HIV-1 infected children and adolescents: A longitudinal study in rural Zimbabwe

INTRODUCTION

Maintaining virologic suppression of children and adolescents on ART in rural communities in sub-Saharan Africa is challenging. We explored switching drug regimens to protease inhibitor (PI) based treatment and reducing nevirapine and zidovudine use in a differentiated community service delivery model in rural Zimbabwe.

METHODS

From 2016 through 2018, we followed 306 children and adolescents on ART in Hurungwe, Zimbabwe at Chidamoyo Christian Hospital, which provides compact ART regimens at 8 dispersed rural community outreach sites. Viral load testing was performed (2016) by Roche and at follow-up (2018) by a point of care viral load assay. Virologic failure was defined as viral load ≥1,000 copies/ml. A logistic regression model which included demographics, treatment regimens and caregiver's characteristics was used to assess risks for virologic failure and loss to follow-up (LTFU).

RESULTS

At baseline in 2016, 296 of 306 children and adolescents (97%) were on first-line ART, and only 10 were receiving a PI-based regimen. The median age was 12 years (IQR 8-15) and 55% were female. Two hundred and nine (68%) had viral load suppression (<1,000 copies/ml) and 97(32%) were unsuppressed (viral load ≥1000). At follow-up in 2018, 42/306 (14%) were either transferred 23 (7%) or LTFU 17 (6%) and 2 had died. In 2018, of the 264 retained in care, 107/264 (41%), had been switched to second-line, ritonavir-boosted PI with abacavir as a new nucleotide analog reverse transcriptase inhibitor (NRTI). Overall viral load suppression increased from 68% in 2016 to 81% in 2018 (P<0.001).

CONCLUSION

Viral load testing, and switching to second-line, ritonavir-boosted PI with abacavir significantly increased virologic suppression among HIV-infected children and adolescents in rural Zimbabwe.

Treatment with tenofovir disoproxil fumarate or entecavir in chronic hepatitis B virus-infected patients with renal impairment: results from a 7-year, multicentre retrospective cohort study

BACKGROUND

Limited data exist regarding tenofovir disoproxil fumarate (TDF) safety and effectiveness in chronic hepatitis B virus-infected (CHB) patients with renal impairment (RI).

AIMS

To compare real-world data on renal safety and effectiveness of TDF vs entecavir (ETV) in CHB patients with moderate-to-severe RI.

METHODS

Retrospective, non-interventional, cohort study analysing medical records for TDF/ETV-treated CHB patients (54 European centres). Included patients experienced moderate-to-severe RI (creatinine clearance 20-60 mL/min [Cockcroft-Gault]) either before TDF/ETV initiation ('before' subgroup [baseline = treatment initiation]) or after TDF/ETV initiation ('after' subgroup [baseline = first RI occurrence]). The primary objective was TDF safety, particularly renal-related adverse events of special interest (AESI). TDF and ETV safety and effectiveness were compared and multivariate analyses were performed using inverse probability treatment weighting.

RESULTS

'Before' subgroup included 107 TDF- and 91 ETV-treated patients; 'after' subgroup included 212 TDF- and 77 ETV-treated patients. Mean baseline creatinine clearance was higher for TDF- vs ETV-treated patients (both subgroups). Median follow-up was 3.1 years (both treatments). AESI were more frequent with TDF vs ETV ('before': 18.7% vs 8.8%; 'after': 9.9% vs 3.9%); however, differences were not significant by multivariate analysis. Only TDF-treated patients experienced renal tubular dysfunction (6.5% 'before'; 1.9% 'after') as well as renal adverse events leading to treatment discontinuation (8.4% 'before'; 7.1% 'after'). Effectiveness was similar between treatments.

CONCLUSIONS

Overall safety was similar for TDF vs ETV (both subgroups). Given that renal tubular dysfunction occurred with TDF and not with ETV, renal safety concerns may be greater with TDF in CHB patients with RI.

Comparison of Zidovudine and Tenofovir Based Regimens With Regard to Health-Related Quality of Life and Prevalence of Symptoms in HIV Patients in a Kenyan Referral Hospital

Aim: Zidovudine and tenofovir form the backbone of antiretroviral therapy in Kenya. However, their side-effects may affect the quality of life (QoL) of patients. The aim was to compare the health-related quality of life (HRQoL) of adult patients on tenofovir versus zidovudine based regimens in a referral hospital in Kenya to provide future guidance.

Methods: A comparative cross sectional study among 501 adult out-patients on either tenofovir or zidovudine was undertaken in Kenyatta National Hospital between 2015 and 2016. The Medical Outcome Study HIV Health Survey (MOS-HIV) was administered along with other key aspects of treatment. Linear regression analysis was performed to identify determinants of HRQoL.

Results: Patients on zidovudine had a higher Physical Health Summary Score (PHSS) and Mental Health Summary Score (MHSS) compared to those on tenofovir. The presence of any symptom of the disease and a stated inability to cope were negatively associated with PHSS, whilst having a regular source of income improved PHSS. Being on tenofovir, symptom of illness [β = -1.24; 95% CI (-2.253, -0.226)], absence of pain [β=0.413; 95% CI (0.152, 0.674)] and patient stated inability to cope with HIV [β = -1.029; 95% CI (-1.441, -0.617)] affected the MHSS. Patients on tenofovir and second line regimens had more signs and symptoms of illness.

Conclusion: Participants on zidovudine based regimens showed a better performance across all aspects of HRQoL. These are considerations for the future.

Complications of Treatment in Youth with HIV

While combination antiretroviral therapy allows HIV-infected patients to have life expectancies similar to that of the general population, it may also contribute to the development of co-morbidities, such as cardiovascular disease and osteoporosis. Such complications could compromise long-term quality of life, especially in HIV-infected youth whose lifetime cumulative exposure to antiretrovirals is likely to be many decades. Recent studies continue to demonstrate abnormalities associated with antiretroviral therapy, although clinical manifestations are rare in this younger population, especially with modern antiretrovirals. The purpose of this paper is to review the most recent literature on complications of treatment in youth with HIV.

Renal and Bone Adverse Effects of a Tenofovir-Based Regimen in the Treatment of HIV-Infected Children: A Systematic Review

INTRODUCTION

Tenofovir disoproxil fumarate (TDF)-containing regimens in the treatment of HIV-infected children have safety concerns with respect to renal and bone toxicity.

OBJECTIVE

The aim of this study was to systematically review and critically appraise the literature relating to the reported renal and bone adverse effects of TDF-based regimens in the treatment of HIV-infected children from 2 to 19 years old.

METHODS

Searches were performed using the Cochrane Central Register of Controlled Trials (CENTRAL), Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, OvidSP, ScienceDirect and Web of Science databases and platforms. All primary studies involving tenofovir use in HIV-infected children were sought. Studies that involved the use of TDF for pre- and post-exposure prophylaxis, and treatment of chronic hepatitis B virus infection were excluded. Data on study characteristics, participant's characteristics, therapeutic intervention and adverse effects were extracted using a piloted tool. In addition, pharmacovigilance data from the WHO Adverse Reaction database were included.

RESULTS

We identified 19 studies that reported the presence of renal and bone adverse effects of TDF and these included a total of 1100 study participants. The reports were in distinctly heterogeneous participant groups. A total of 287 renal and bone adverse effects were reported (250 renal and 37 bone adverse effects). Approximately 238 (21.6 %) participants were affected by these adverse effects. Of these, 15 participants stopped their TDF-containing regimen due to these adverse effects. In addition, the pharmacovigilance data from the WHO Adverse Reaction database reported 101 renal and bone adverse effects for patients whose indication was HIV/AIDS.

CONCLUSION

This systematic review summarises the reports of renal and bone adverse effects of a TDF-containing regimen in the treatment of HIV-infected children. Our findings suggest that the benefits of using TDF in children need to be balanced against the potential risk of toxicity.

Bone health in HIV-infected children and adolescents

PURPOSE OF REVIEW

Chronic HIV infection and exposure to antiretroviral therapy compromises bone health in children and adolescents, potentially impacting their long-term quality of life. Thus, the purpose of this article is to review the most recent literature on this topic in HIV-infected children and adolescents.

RECENT FINDINGS

Recent studies continue to demonstrate bone abnormalities in HIV-infected children and adolescents, whether HIV is acquired perinatally or during adolescence. Researchers have employed new modalities, both high tech and those that can be utilized in resource-limited settings, to better assess bone health. New data suggest that this population may also be experiencing an increase incidence of fractures, and they may not acquire the same peak bone mass as their HIV-uninfected counterparts. Reassuringly, however, in-utero tenofovir exposure does not appear to have a significant impact on bone health in HIV-exposed, uninfected infants.

SUMMARY

HIV-infected children and adolescents are exposed to HIV and antiretroviral therapy for many decades starting early in life and during the most critical time for skeletal growth and bone mass accrual. Recent findings underscore the need for further research on bone in this population. Longitudinal studies are especially needed to evaluate long-term risk of osteoporosis and fracture.

Long-term renal effects of tenofovir-disoproxil-fumarate in vertically HIV-infected children, adolescents, and young adults: a 132-month follow-up study

BACKGROUND AND OBJECTIVES

The introduction of highly active anti-retroviral therapy has led to a significant decline in morbidity and mortality. Although several studies in adult populations have shown that tenofovir-disoproxil-fumarate (TDF) use is associated with a significant loss of renal function, there is still uncertainty on the long-term TDF safety profile in pediatric HIV populations, mostly in vertically HIV-infected patients. The aim of this study was to evaluate the long-term TDF renal safety profile, during a ten-year follow up.

METHODS

Twenty-six vertically HIV-infected patients were evaluated for a total of 132 months of follow up, monitoring anthropometric parameters, renal function, viral load and CD4+ count. Generalized estimating equations were used to evaluate the changes in anthropometric and laboratory variables. Multivariable fractional polynomials were used to test for the existence of non-linear relationships of outcomes with time and other continuous covariates. In all patients, weight, height and body mass index increased linearly with time. CD4+ count and glomerular filtration rate decreased linearly with time (p < 0.01).

RESULTS

No significant increase of serum creatinine was registered. An inverse linear relationship between time and plasma phosphate was found. Hypophosphatemia was detected in 17 patients, mostly mild. In 14 out of 17 we also genotyped single nucleotide polymorphisms rs717620 mapping in ABCC2, a gene encoding for a renal transporter.

CONCLUSIONS

Our study demonstrates the relative safety of prolonged use of TDF in vertically HIV-infected children and young adults. The most relevant alteration that emerged was hypophosphatemia, appearing after 72 months of TDF therapy, mostly mild and without clinical significance.

Paediatric HIV: Progress on Prevention, Treatment and Cure

PURPOSE OF REVIEW

This review provides an update on current developments with prevention, treatment and cure strategies in the field of pediatric HIV.

RECENT FINDINGS/SUMMARY

There has been tremendous progress in the prevention and treatment of pediatric HIV infection. With new strategies for prevention of mother-to-child transmission, we are growing ever closer towards elimination of pediatric HIV, though challenges with retention of pregnant woman and their HIV-exposed infants remain. Ongoing vigilance regarding the potential hazards of in utero ART exposure to infants continues with no significant alarms yet identified. Though cure has not been achieved, evidence of the impact of early treatment on reducing HIV-1 reservoir size with subsequent prolonged remission has enlivened efforts to rapidly identify and treat HIV-infected newborns. There is an increasing array of treatment options for pediatric patients and reassuring evidence regarding long-term complications of ART. Unfortunately, despite evidence suggesting the benefit of early treatment, timely identification and treatment of children remains a challenge. Better strategies for effective case-finding and engagement in care are urgently needed in addition to an improved understanding of how to retain HIV-positive children and adolescents on treatment. However, further emboldened by recent international commitments and robust global support, the future is hopeful.

Review of tenofovir use in HIV-infected children

Tenofovir disoproxil fumarate (TDF) is approved by the Food and Drug Administration for use in children ages 2 years and older and is recommended by the World Health Organization for use as a preferred first-line nucleotide reverse transcriptase inhibitor in adults and adolescents ages 10 years and older. The simplicity of once daily dosing, few metabolic side effects and efficacy against hepatitis B virus make TDF suitable for use in a large scale program. Unlike thymidine analoge nucleoside reverse transcriptase inhibitors (NRTIs); tenofovir does not induce multi-NRTI resistance mutations, so more NRTI options are available for future second-line-regimens. Fixed-dose combinations of TDF with other ARVs as a single tablet regimen are now widely available for adults and adolescents, but none are available for young children. Current information on TDF including the pharmacokinetics, safety and tolerability in children and adolescents was reviewed. A dosing regimen according to body-weight-band has been established for pediatric use. Safety concerns of TDF mainly relate to its effects on renal function and bone mineral density. Regular monitoring of renal function in high-risk patients, including those on other nephrotoxic drugs, may be warranted to detect adverse renal effects. Long-term-data on renal and bone outcomes among HIV-infected children is needed. Lessons learned from clinical studies will help clinicians balance the risks and benefits of TDF and design appropriate antiretroviral regimens for children in different circumstances.