Successful simplification of protease inhibitor-based HAART with triple nucleoside regimens in children vertically infected with HIV

Preservation of lymphocyte functional fitness in perinatally-infected and treated HIV+ pediatric patients displaying sub-optimal viral control

Background

Host–pathogen dynamics associated with HIV infection are quite distinct in children versus adults. We interrogated the functional fitness of the lymphocyte responses in two cohorts of perinatally infected HIV+ pediatric subjects with early anti-retroviral therapy (ART) initiation but divergent patterns of virologic control. We hypothesized that sub-optimal viral control would compromise immune functional fitness.

Methods

The immune responses in the two HIV+ cohorts (n = 6 in each cohort) were benchmarked against the responses measured in age-range matched, uninfected healthy control subjects (n = 11) by utilizing tests for normality, and comparison [the Kruskal–Wallis test, and the two-tailed Mann–Whitney U test (where appropriate)]. Lymphocyte responses were examined by intra-cellular cytokine secretion, degranulation assays as well as phosflow. A subset of these data were further queried by an automated clustering algorithm. Finally, we evaluated the humoral immune responses to four childhood vaccines in all three cohorts.

Results

We demonstrate that contrary to expectations pediatric HIV+ patients with sub-optimal viral control display no significant deficits in immune functional fitness. In fact, the patients that display better virologic control lack functional Gag-specific T cell responses and compared to healthy controls they display signaling deficits and an enrichment of mitogen-stimulated CD3 negative and positive lymphocyte clusters with suppressed cytokine production.

Conclusions

These results highlight the immune resilience in HIV+ children on ART with sub-optimal viral control. With respect to HIV+ children on ART with better viral control, our data suggest that this cohort might potentially benefit from targeted interventions that might mitigate cell-mediated immune functional quiescence.

Adverse events associated with abacavir use in HIV-infected children and adolescents: a systematic review and meta-analysis

BACKGROUND

Concerns exist about the toxicity of drugs used in the implementation of large-scale antiretroviral programmes, and documentation of antiretroviral toxicity is essential. We did a systematic review and meta-analysis of adverse events among children and adolescents receiving regimens that contain abacavir, a widely used antiretroviral drug.

METHODS

We searched bibliographic databases and abstracts from relevant conferences from Jan 1, 2000, to March 1, 2015. All experimental and observational studies of HIV-infected patients aged 0-18 years who used abacavir, were eligible. Incidence of adverse outcomes in patients taking abacavir (number of new events in a period divided by population at risk at the beginning of the study) and relative risks (RR) compared with non-abacavir regimens were pooled with random effects models.

FINDINGS

Of 337 records and 21 conference abstracts identified, nine studies (eight full-text articles and one abstract) collected information about 2546 children, of whom 1769 (69%) were on abacavir regimens. Among children and adolescents taking abacavir, hypersensitivity reactions (eight studies) had a pooled incidence of 2·2% (95% CI 0·4-5·2); treatment switching or discontinuation (seven studies) pooled incidence was 10·9% (2·1-24·3); of grade 3-4 adverse events (six studies) pooled incidence was 9·9% (2·4-20·9); and adverse events other than hypersensitivity reaction (six studies) pooled incidence was 21·5% (2·8-48·4). Between-study inconsistency was significant for all outcomes (p<0·0001 for all inconsistencies). Incidence of death (four studies) was 3·3% (95% CI 1·5-5·6). In the three randomised clinical trials with comparative data, no increased risk of hypersensitivity reaction (pooled RR 1·08; 95% CI 0·19-6·15), grade 3 or 4 events (0·79 [0·44-1·42]), or death (1·72 [0·77-3·82]) was noted for abacavir relative to non-abacavir regimens. None of the reported deaths were related to abacavir.

INTERPRETATION

Abacavir-related toxicity occurs early after ART initiation and is manageable. Abacavir can be safely used for first-line or second-line antiretroviral regimens in children and adolescents, especially in sub-Saharan Africa were HLA B5701 genotype is rare.

FUNDING

WHO.

A systematic review of a single-class maintenance strategy with nucleoside/nucleotide reverse transcriptase inhibitors in HIV/AIDS

BACKGROUND

Single-drug class regimens with nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) are generally not recommended as initial therapy because they are inferior compared with therapy with two NRTIs plus efavirenz. However, triple-NRTI combinations can be useful in specific circumstances such as in tuberculosis coinfection, pregnancy or dyslipidaemia. Here, we review the potential of such combinations to maintain viral suppression after induction of suppression by standard combination antiretroviral therapy (cART) and to evaluate the trade-off of NRTI-only regimens for metabolic control.

METHODS

We conducted a systematic search of the literature in two databases from 1 January 1998 up to 1 March 2013: Medline, through the search engine PubMed, and Embase.

RESULTS

A total of 11 randomized controlled trials (RCTs) with 2,105 patients and 3 observational studies with 2,639 patients were included. Studies including patients with mono- or dual-NRTI treatment before start of effective cART showed a tendency to higher failure rate because of resistance based on archived viral mutations. In studies with ART-naive subjects before start of cART, triple-NRTI combination showed virological activity comparable to two NRTIs plus a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor in all RCTs, but not in one cohort study. Switching improved serum lipids significantly.

CONCLUSIONS

Of the studied triple-NRTI combinations only abacavir/lamivudine/zidovudine was sufficiently potent. Triple-NRTI maintenance after successful induction with two-class cART appeared successful in treatment-naive subjects and remains a useful option in specific circumstances, especially when other drugs are not available or drug interactions are an issue.

Therapeutic DNA vaccination of vertically HIV-infected children: report of the first pediatric randomised trial (PEDVAC)

Subjects

Twenty vertically HIV-infected children, 6–16 years of age, with stable viral load control and CD4+ values above 400 cells/mm³.

Intervention

Ten subjects continued their ongoing antiretroviral treatment (ART, Group A) and 10 were immunized with a HIV-DNA vaccine in addition to their previous therapy (ART and vaccine, Group B). The genetic vaccine represented HIV-1 subtypes A, B and C, encoded Env, Rev, Gag and RT and had no additional adjuvant. Immunizations took place at weeks 0, 4 and 12, with a boosting dose at week 36. Monitoring was performed until week 60 and extended to week 96.

Results

Safety data showed good tolerance of the vaccine. Adherence to ART remained high and persistent during the study and did not differ significantly between controls and vaccinees. Neither group experienced either virological failure or a decline of CD4+ counts from baseline. Higher HIV-specific cellular immune responses were noted transiently to Gag but not to other components of the vaccine. Lymphoproliferative responses to a virion antigen HIV-1 MN were higher in the vaccinees than in the controls (p = 0.047), whereas differences in reactivity to clade-specific Gag p24, RT or Env did not reach significance. Compared to baseline, the percentage of HIV-specific CD8+ lymphocytes releasing perforin in the Group B was higher after the vaccination schedule had been completed (p = 0.031). No increased CD8+ perforin levels were observed in control Group A.

Conclusions

The present study demonstrates the feasibility, safety and moderate immunogenicity of genetic vaccination in vertically HIV-infected children, paving the way for amplified immunotherapeutic approaches in the pediatric population.

Trial registration

clinicaltrialsregister.eu _2007-002359-18IT

Use of nucleoside reverse transcriptase inhibitor-only regimens in HIV-infected children and adolescents

OBJECTIVE

In adults, nucleoside reverse transcriptase inhibitor-only antiretroviral regimens (NOARs) with ≥3 nucleoside reverse transcriptase inhibitors are less potent than highly active antiretroviral therapy (HAART). Published pediatric experience with NOARs is limited; thus, we wished to better define the virological, immunological and toxicological effects of NOARs in children and adolescents.

METHODS

We analyzed data from NOAR-treated participants in LEGACY, a multicenter observational cohort study of HIV-infected children and adolescents. NOAR-treated case-participants were matched to participants without prior NOAR who initiated HAART during the same year for comparison.

RESULTS

Of 575 participants with data from time of HIV diagnosis through 2006, 67 (12%) received NOARs for at least 24 weeks; most (46%) received the fixed dose combination of zidovudine/lamivudine/abacavir. NOAR use peaked in 2001 to 2002. NOAR-treated participants were significantly older and more treatment experienced than HAART-treated participants. Virologic outcomes, including the percentage of participants with a plasma HIV RNA viral load <400 copies/mL at week 24 (47% versus 34%) and the mean 24-week change in log10 plasma HIV RNA viral load from baseline (-0.63 versus -1.02), were similar between NOAR- and HAART-treated participants, but virologic rebound was more likely in NOAR-treated participants (77% versus 54%, P = 0.02). Increase in CD4 percentage points from baseline to 24 weeks was negligible in NOAR-treated participants compared with HAART-treated participants (0.95% versus 10.1%, P < 0.001). Anemia and leukopenia were more commonly reported with NOARs than HAART.

DISCUSSION

Week 24 virologic outcomes were similar between NOAR- and HAART-treated participants, but NOAR durability was poorer and their use was associated with less immunologic reconstitution. NOARs should play a limited role in pediatric and adolescent antiretroviral therapy.

Abacavir-based triple nucleoside regimens for maintenance therapy in patients with HIV

BACKGROUND

Regimen simplification can be defined as a change in established effective therapy to reduce pill burden and dosing frequency, to enhance tolerability, or to decrease specific food and fluid requirements. Many patients on suppressive antiretroviral therapy may be considered candidates for a simplification strategy and, among them, those who have achieved virologic suppression. Several clinical trials have evaluated the efficacy of triple nucleoside combination as a simplification therapy in patients who achieved virologic suppression

OBJECTIVES

The aim of this review is to combine randomised, controlled trials to examine whether in patients with undetectable viraemia on a Protease inhibitor (PI) based regimen simplification treatment with abacavir (ABC)-based triple-nucleoside combinations has similar rates of efficacy and tolerability compared with a PI regimen or simplification with a NNRTIs (efavirenz-EFV- or nevirapine-NVP) containing regimen. Studies were included if they had at least two of the three interventions, including one 3NRTI arm.

SEARCH METHODS

Electronic databases and conference proceedings were searched (1996-2012) with relevant search terms without limits to language.

SELECTION CRITERIA

Randomised controlled trials (RCTs) only are included in this review. Patients population is represented by HIV-infected adult patients treated with a PI-containing regimen (PI or boosted PI),  with undetectable viral load. Patients on a PI-containing regimen had three possibilities: continue the PI regimen or switch to a simplification maintenance regimen, including switch to a NNRTI (EFV or NVP) containing regimen, or switch to a triple-NRTI regimen (ABC-zidovudine-lamivudine)

DATA COLLECTION AND ANALYSIS

The primary outcomes were: proportion of patients discontinuing or switching antiretroviral therapy due to virologic failure or to adverse events; death (all cause) and AIDS defining illness; occurrence of myocardial infarction and cardiovascular disease. Secondary outcomes  were: proportion of patients maintaining an undetectable viral load (e.g. HIV-RNA <50 or <400 copies/mm(3)); change in mean CD4+ cell count; occurrence of lipodystrophy. We applied Cochrane Collaboration tools to assess each individual study for risk for bias.

MAIN RESULTS

We included eight RCT, for a total of 1,610 patients. All the studies included HIV-1 infected patients virologically suppressed after a successful treatment with PI containing ART. Articles included in the analysis were published between 2001 and 2010, and could be classified as low risk of bias trials in most of the domains considered. Overall, there was no significant difference between the participants on triple nucleoside combination and controls, either PI-based or NNRTI based in terms of overall failures, death and AIDS related events, and rates of patients with viral load below the detectability cut-off. For the outcomes discontinuation for adverse events and virologic failures, the RRs were not significant , albeit  being not far from the alpha level of 0.05, thus suggesting a weak evidence of lower incidence of side effects  and an higher incidence of virologic failure in the 3NRTI group compared to controls . Change in lipids and in CD4 cells from baselines were reported in 7 studies, but inconsistency in reporting these data did not allow quantitative analysis. However, all agreed that simplification with ABC had a favourable and significant impact on lipid metabolism compared to control group. An increase in CD4 cells count from baseline was evident in all analysed studies, without significant differences between ABC and controls in individual studies.

AUTHORS' CONCLUSIONS

The strategy of switching to triple nucleoside regimens shows weak evidence of lower incidence of side effects and a higher incidence of virologic failure in the 3NRTI group compared to controls. Simplification with 3NRTI holds the advantages of preserving other classes of antiretroviral drugs, to lower blood lipids, and to be cost effective and simple to administer.Thus, simplification with triple nucleoside regimens AZT + 3TC + ABC should be still considered for individuals who are unable to tolerate or have contraindications to NNRTI or PI based regimens. Additional data are needed on longer-term efficacy of triple NRTI regimens, particularly on the development of antiretroviral resistance. Though studies in the current review were conducted between 2001 and 2010, the large majority of patients from studies analysed received old PI regimens (e.g., indinavir, ritonavir, nelfinavir, saquinavir) not longer recommended by International Guidelines. Since current guidelines recommend new "lipid -friendly" PI, future studies should compare regimens containing these news PIs to triple NRTI regimens. More realistically, however, there are opportunities to examine these issues in existing cohorts.

Suboptimal immune reconstitution in vertically HIV infected children: a view on how HIV replication and timing of HAART initiation can impact on T and B-cell compartment

Today, HIV-infected children who have access to treatment face a chronic rather than a progressive and fatal disease. As a result, new challenges are emerging in the field. Recent lines of evidence outline several factors that can differently affect the ability of the immune system to fully reconstitute and to mount specific immune responses in children receiving HAART. In this paper, we review the underlying mechanisms of immune reconstitution after HAART initiation among vertically HIV-infected children analyzing the possible causes of suboptimal responses.

Antiretroviral therapy for children in resource-limited settings: current regimens and the role of newer agents

WHO antiretroviral treatment guidelines for HIV-infected children have influenced the design of treatment programmes in resource-limited settings. This review analyses the latest WHO first- and second-line regimen recommendations. The recommendation to use lopinavir/ritonavir-containing first-line regimens in young children with prior non-nucleoside reverse transcriptase inhibitor (NNRTI) exposure is based on good quality evidence. Recent research suggests that lopinavir/ritonavir-containing first-line regimens should be extended to all young children, irrespective of prior NNRTI exposure. Strategies for overcoming the adverse metabolic effects of rifampicin-containing anti-tuberculosis therapy on antiretroviral therapy regimens have been under-researched in HIV-infected children, creating uncertainty about global recommendations. Preferred second-line recommendations are largely predictable. The exception is that NNRTI-containing second-line regimens are recommended for children previously exposed to NNRTIs and who subsequently did not respond to lopinavir/ritonavir-containing first-line therapy. In these patients, second-line regimens containing newer protease inhibitors (PIs) such as darunavir and tipranavir, or integrase inhibitors such as raltegravir, should be evaluated. Newer antiretroviral agents including second-generation NNRTIs and PIs, C-C chemokine receptor type 5 inhibitors, and integrase inhibitors may assist in further refinement of existing regimen options.

HIV is associated with thrombophilia and high D-dimer in children and adolescents

BACKGROUND AND OBJECTIVE

Atherosclerosis and other cardiovascular diseases associated with thrombosis appear more relevant and anticipated in HIV-infected patients after combination antiretroviral therapy (cART) has reduced AIDS-related diseases and has improved survival. The association between viral replication and coagulation abnormalities in a cohort of HIV-infected children and adolescents was investigated here.

METHODS

Protein S, protein C anticoagulant and antithrombin activity, together with fibrinogen, D-dimer, high-sensitive C-reactive protein and homocysteine were assayed in a cross-sectional study among a cohort of HIV-infected children and adolescents. Results in patients with high viral load (HVL, HIV-RNA > 1000 copies/ml) were compared with those in patients with a lower replication (LVL), adjusting for other demographic, clinical and therapeutic covariates.

RESULTS

Eighty-eight patients (mean age 13.5 years, CD4 30%, 72% with LVL) were enrolled. A prevalence of protein S and protein C deficiency of 51 and 8% was, respectively, found. HVL group compared to LVL showed a significant reduction of protein S, protein C and antithrombin activities, and an increase of D-dimer levels. The independent association of HVL with decreased protein S activity (-11.2%, P = 0.04) and increased D-dimer levels (+0.13 microg/ml, P = 0.004) was confirmed in the multivariate model.

CONCLUSIONS

HIV-infected children and adolescents present high prevalence of thrombophilic abnormalities. The multivariate model confirmed that high viral replication is independently associated with decrease of protein S and increase of D-dimer, suggesting the advantage of suppressive therapy on coagulation homeostasis and the opportunity of an active control of cardiovascular risk factors starting at a younger age.

Nevirapine/zidovudine/lamivudine has superior immunological and virological responses not reflected in clinical outcomes in a 48-week randomized comparison with abacavir/zidovudine/lamivudine in HIV-infected Ugandan adults with low CD4 cell counts

BACKGROUND

Triple nucleoside reverse transcriptase inhibitor regimens have advantages as first-line antiretroviral therapy (ART), avoiding hepatotoxicity and interactions with anti-tuberculosis therapy, and sparing two drug classes for second-line ART. Concerns exist about virological potency; efficacy has not been assessed in Africa.

METHODS

A safety trial comparing nevirapine with abacavir was conducted in two Ugandan Development of Antiretroviral Therapy in Africa (DART) centres: 600 symptomatic antiretroviral-naïve HIV-infected adults with CD4 counts <200 cells/microL were randomized to zidovudine/lamivudine plus abacavir or nevirapine (placebo-controlled to 24-week primary toxicity endpoint, and then open-label). Documented World Health Organization (WHO) stage 4 events were independently reviewed and plasma HIV-1 RNA assayed retrospectively. Exploratory efficacy analyses are intention-to-treat.

RESULTS

The median pre-ART CD4 count was 99 cells/microL, and the median pre-ART viral load was 284 600 HIV-1 RNA copies/mL. A total of 563 participants (94%) completed 48 weeks of follow-up, 25 (4%) died and 12 (2%) were lost to follow-up. The randomized drug was substituted in 21 participants (7%) receiving abacavir vs. 34 (11%) receiving nevirapine (P=0.09). At 48 weeks, 62% of participants receiving abacavir vs. 77% of those receiving nevirapine had viral loads <50 copies/mL (P<0.001), and mean CD4 count increases from baseline were +147 vs. +173 cells/microL, respectively (P=0.006). Nine participants (3%) receiving abacavir vs. 16 (5%) receiving nevirapine died [hazard ratio (HR) 0.55; 95% confidence interval (CI) 0.24-1.25; P=0.15]; 20 receiving abacavir vs. 32 receiving nevirapine developed new or recurrent WHO 4 events or died (HR=0.60; 95% CI 0.34-1.05; P=0.07) and 48 receiving abacavir vs. 68 receiving nevirapine developed new or recurrent WHO 3 or 4 events or died (HR=0.67; 95% CI 0.46-0.96; P=0.03). Seventy-one participants (24%) receiving abacavir experienced 91 grade 4 adverse events compared with 130 events in 109 participants (36%) on nevirapine (P<0.001).

CONCLUSIONS

The clear virological/immunological superiority of nevirapine over abacavir was not reflected in clinical outcomes over 48 weeks. The inability of CD4 cell count/viral load to predict initial clinical treatment efficacy is unexplained and requires further evaluation.

Delayed early antiretroviral treatment is associated with an HIV-specific long-term cellular response in HIV-1 vertically infected infants

Antiviral T-cell immune responses appear to be crucial to control HIV replication. Infants treated before the third month of life with highly active antiretroviral treatment (HAART) did not develop a persistent HIV-specific immune response. We evaluated how delayed initiation of HAART after 3 months of age influences the development of HIV-1-specific T-cell responses during long-term follow-up in 9 HIV-1 vertically infected infants. These data suggest that a longer antigenic stimulation, due to a larger window for therapeutic intervention with HAART, is associated with the establishment of a persistent specific HIV immune response resulting in a long-term viral control of vertically infected infants.