Structured Therapy Interruption Research Articles

Immunotherapy with an HIV-DNA Vaccine in Children and Adults.

Therapeutic HIV immunization is intended to induce new HIV-specific cellular immune responses and to reduce viral load, possibly permitting extended periods without antiretroviral drugs. A multigene, multi-subtype A, B, C HIV-DNA vaccine (HIVIS) has been used in clinical trials in both children and adults with the aim of improving and broadening the infected individuals’ immune responses. Despite the different country locations, different regimens and the necessary variations in assays performed, this is, to our knowledge, the first attempt to compare children’s and adults’ responses to a particular HIV vaccine. Ten vertically HIV-infected children aged 4–16 years were immunized during antiretroviral therapy (ART). Another ten children were blindly recruited as controls. Both groups continued their antiretroviral treatment during and after vaccinations. Twelve chronically HIV-infected adults were vaccinated, followed by repeated structured therapy interruptions (STI) of their antiretroviral treatment. The adult group included four controls, receiving placebo vaccinations. The HIV-DNA vaccine was generally well tolerated, and no serious adverse events were registered in any group. In the HIV-infected children, an increased specific immune response to Gag and RT proteins was detected by antigen-specific lymphoproliferation. Moreover, the frequency of HIV-specific CD8+ T-cell lymphocytes releasing perforin was significantly higher in the vaccinees than the controls. In the HIV-infected adults, increased CD8+ T-cell responses to Gag, RT and viral protease peptides were detected. No augmentation of HIV-specific lymphoproliferative responses were detected in adults after vaccination. In conclusion, the HIV-DNA vaccine can elicit new HIV-specific cellular immune responses, particularly to Gag antigens, in both HIV-infected children and adults. Vaccinated children mounted transient new HIV-specific immune responses, including both CD4+ T-cell lymphoproliferation and late CD8+ T-cell responses. In the adult cohort, primarily CD8+ T-cell responses related to MHC class I alleles were noted. However, no clinical benefits with respect to viral load reduction were ascribable to the vaccinations alone. No severe adverse effects related to the vaccine were found in either cohort, and no virological failures or drug resistances were detected.

Amplified antigen-specific immune responses in HIV-1 infected individuals in a double blind DNA immunization and therapy interruption trial

Immunotherapy in patients with HIV-1 infection aims to restore and broaden immunological competence, reduce viral load and thereby permit longer periods without combined antiretroviral treatment (cART). Twelve HIV-1-infected patients on cART were immunized on the skin with DNA plasmids containing genes of several HIV-1 subtypes with or without the addition of hydroxyurea (HU), or with placebo. The mean net gain of HIV-specific CD8+ T cell responses were higher and broader in the HIV DNA vaccine groups compared to non-vaccinated individuals (p<0.05). The vaccine-induced immune responses per se had no direct effect on viral replication. In all patients combined, including placebo, the viral set point after a final structured therapy interruption (STI) was lower than prior to initiation of cART (p=0.003). Nadir CD4 levels appeared to strongly influence the post-STI viral titers. After the sixth immunization or placebo, patients could stay off cART for a median time of 15 months. The study shows that HIV DNA immunization induces broader and higher magnitudes of HIV-specific immune responses compared to structured therapy interruptions alone. Although compromised by small numbers of patients, the study also demonstrates that well-monitored STI may safely function as an immunological read out of HIV vaccine efficacy.

Five-year follow-up of children with perinatal HIV-1 infection receiving early highly active antiretroviral therapy

BackgroundEarly highly active antiretroviral therapy (HAART), started within the first months of age, has been proven to be the optimal strategy to prevent immunological and clinical deterioration in perinatally HIV-infected children. Nevertheless, data about long-term follow-up of early treated children are lacking.MethodsWe report data from 40 perinatally HIV-infected-children receiving early HAART, with a median follow-up period of 5.96 years (interquartile range [IQR]:4.21–7.62). Children were enrolled at birth in the Italian Register for HIV Infection in Children. Comparison with 91 infected children born in the same period, followed-up from birth, and receiving deferred treatment was also provided.ResultsNineteen children (47.5%) were still receiving their first HAART regimen at last follow-up. In the remaining children the first regimen was discontinued, after a median period of 3.77 years (IQR: 1.71–5.71) because of viral failure (8 cases), liver toxicity (1 case), structured therapy interruption (3 cases), or simplification/switch to a PI-sparing regimen (9 cases). Thirty-nine (97.5%) children showed CD4+ T-lymphocyte values>25%, and undetectable viral load was reached in 31 (77.5%) children at last visit. Early treated children displayed significantly lower viral load than not-early treated children, until 6 years of age, and higher median CD4+ T-lymphocyte percentages until 4 years of age. Twenty-seven (29.7%) not-early treated vs. 0/40 early treated children were in clinical category C at last follow-up (P < 0.0001).ConclusionOur findings suggest that clinical, virologic and immunological advantages from early-HAART are long-lasting. Recommendations indicating the long-term management of early treated children are needed.

Short Communication: Natural Killer Cells and Expression of KIR Receptors in Chronic HIV Type 1-Infected Patients after Different Strategies of Structured Therapy Interruption

Few data evaluating the NK cell profile during structured therapy interruption (STI) in chronic HIV-1 infection are available. Changes in NK cell percentages and KIR and NKG2A receptors were analyzed at baseline and after 2 years of follow-up in 121 patients on ART with CD4(+) >450 cells/ml and VL <200 copies/ml randomized in three arms according to the criteria employed to resume ART during STI: virological arm (VA n = 47, VL >30,000 copies/ml or CD4 <350 cells/ml), immunological arm (IA n = 37, CD4< 350 cells/ml), and a control arm (n = 37) in which ART was maintained. After 2 years of follow-up, a decrease in CD3(-)CD56(+) CD16(+) cell percentages in VA and IA patients, but not in CA patients, was observed. Those patients with higher decrease in CD3(-)CD56(+)CD16(+) cells had a higher decrease in CD4(+) cells (r = 0.35, p = 0.001) and higher increase in PVL (r = -0.26, p = 0.02). KIR and NKG2A receptor expression tended to increase in CA and decreased in the other two arms (more in IA than in VA). Patients who displayed a greater decrease in CD4(+) T cells and a greater rise in PVL after 2 years of follow-up had a significantly higher decrease in KIR and NKG2A receptors expressed in CD3(-)CD56(+) cells. Patients who presented the lowest levels of total NK cells and KIR and NKG2A receptor expression after STI showed the poorest virology or immunology outcomes. This finding suggests that STI could decrease the number of NK subsets, which is related to the worst clinical development in these patients.

Influence of repeated cycles of structured therapy interruption on the rate of recovery of CD4+ T cells after highly active antiretroviral therapy resumption

CD4+ T cell recovery dynamics were analysed during the 'on treatment' periods in structured therapy interruption (STI) as well as the long-term immune reconstitution with highly active antiretroviral therapy (HAART) after finishing STI. One hundred and twenty HIV-1-infected patients on successful HAART were randomized to receive for 2 years continuous HAART (n=37) or two different strategies of STI (n=83). After this period, most patients received continuous HAART for 2 years. During the STI period, the rate of recovery of CD4+ T cells decreased progressively from the first to the last resumption of HAART {median change of increase: +232 [interquartile range (IQR): +126, +318], +116 (IQR: +10, +471), +87 (IQR: -54, +252) and -26 (IQR: -352, +211) cells/mm3 after the first, second, third and fourth resumption, respectively}. After the STI period and 2 years of continuous HAART, the median CD4+ count remained significantly lower than at baseline in STI arms, both in the virological arm [559 (IQR: 383, 727) versus 771 (IQR: 625, 913) cells/mm3, P<0.0001] and the immunological arm [619 (IQR: 501, 789) versus 787 (IQR: 657, 954) cells/mm3, P<0.0001], but not in the control arm [886 (IQR: 564, 1122) versus 780 (IQR: 539, 945) cells/mm3, P=0.68]. In a multivariate analysis, the nadir of CD4+ T cells and the baseline value of CD4+ before the STI period independently predicted the level of CD4+ T cells 2 years after resumption of HAART (in both cases, P<0.0001). The drop in CD4+ cell count after a first and a second period of 3 months of interruption of HAART was completely recovered after resuming HAART; conversely, interruptions longer than 6 months were deleterious for the recovery of CD4+. CD4+ cell count did not rebound completely in patients who received 2 years of HAART after 2 years of STIs.

Interferon May Prevent HIV Viral Rebound After HAART Interruption in HIV Patients

In the pre-highly active antiretroviral therapy (HAART) era, clinical trials showed that interferon (IFN) treatment was able to delay AIDS progression and prolong survival. Along with HAART, ancillary use of IFN during primary infection and before HAART therapy initiation has been effective. Also endogenous IFN may positively affect the progression of HIV infection, as suggested in GB virus type C (GBV-C) coinfected patients. In this pilot study, we tried to prevent rebound of HIV replication in patients who interrupted HAART by covering the drug-free time with administration of pegylated IFN (PEGIFN). Twenty-four HIV-hepatitis C virus (HCV) patients who started IFN treatment for liver disease, after variable time from having interrupted HAART, were enrolled. HIV RNA was determined during a 2-month period. In patients who interrupted HAART at variable times before initiating IFN and, therefore, had experienced a complete viral rebound, IFN caused a significant reduction of viral load lasting at least 4 weeks. Moreover, 3 of the 4 patients who started IFN concomitantly with the HAART discontinuation showed complete control of viral rebound, delaying the resumption of viral replication for more than 2 weeks. These preliminary findings suggest that a structured therapy interruptions (STI) strategy may be feasible provided that IFN is administered during the drug-free times, possibly delaying drug resistance, lessening toxicity, reducing costs, and prolonging survival.

Virological characterization of patients treated early is able to control HIV‐1 replication after multiple cycles of structured therapy interruption

This study aimed to define clinical and virological parameters associated with spontaneous control of HIV replication in patients having initiated HAART during primary HIV infection, who underwent structured therapy interruption by two protocols with either fixed or HIV viremia-guided scheme. At the end of the protocol all patients were changed to viremia-guided scheme and observed for 12 months (follow-up). Patients maintaining HIV viremia below the indications for resumption of HAART during the follow-up, were defined controllers, those who had to resume HAART were defined non-controllers. The following parameters were examined: pre-interruption therapy duration, CD4(+), HIV RNA, proviral DNA, evolution of viral quasispecies. No specific advantage was conferred by either interruption of structured therapy in the proportion of controllers and non-controllers. Pre-HAART and zenith CD4(+), pre-therapy interruption, HAART duration, but not pre-HAART HIV RNA, were significantly higher in controllers as compared to non-controllers. HIV RNA levels after the first interruption cycle of therapy were significantly lower in controllers than in non-controllers. Proviral DNA levels were also lower in controllers at this time point. HIV RNA and proviral DNA levels associated with the last interruption of therapy cycle were not different from those associated with the first cycle, and, in spite of multiple waves of virus rebound, very few gag quasispecies variants emerged in each patient. The data suggest that pre-treatment clinical parameters and virological events associated with the first viral rebound are crucial factors in determining the ability to control viral replication after multiple cycles of interruption of treatment.

Current perspectives on HIV-associated lipodystrophy syndrome

In recent years, lipodystrophy and its related complications have changed from an anecdotal issue into a major problem for HIV-infected patients on antiretroviral therapy. Despite great efforts to achieve a consensus in defining this problem, a simple, readily available definition is still lacking. More comprehensive knowledge of the underlying molecular basis and the natural history of body fat changes and metabolic abnormalities is needed to make progress. Also, an objective assessment of body fat is still to be incorporated in clinical practice, so interventions to prevent or treat body fat changes cannot be adequately monitored. Several objective techniques have been used, and all of them have limitations and advantages. There seems to be a good correlation between different techniques for measuring fat, but that is not the case for detecting fat changes. A huge amount of data have been generated on how to manage lipodystrophy. Nevertheless, there is no clinically proven treatment for any feature of lipodystrophy. The only intervention that has been shown to reverse lipoatrophy is the discontinuation of thymidine analogues, but the results obtained are partial or modest at most. Structured therapy interruptions have become an increasingly popular strategy aimed at preventing or reducing antiretroviral drug toxicity, but little objective data exist on their impact on body composition of HIV-infected patients. The issue of body composition has become extremely important for the adequate management of HIV-infected patients.

Randomized, Controlled Trial of Therapy Interruption in Chronic HIV-1 Infection

BackgroundApproaches to limiting exposure to antiretroviral therapy (ART) drugs are an active area of HIV therapy research. Here we present longitudinal follow-up of a randomized, open-label, single-center study of the immune, viral, and safety outcomes of structured therapy interruptions (TIs) in patients with chronically suppressed HIV-1 infection as compared to equal follow-up of patients on continuous therapy and including a final therapy interruption in both arms.Methods and FindingsForty-two chronically HIV-infected patients on suppressive ART with CD4 counts higher than 400 were randomized 1:1 to either (1) three successive fixed TIs of 2, 4, and 6 wk, with intervening resumption of therapy with resuppression for 4 wk before subsequent interruption, or (2) 40 wk of continuous therapy, with a final open-ended TI in both treatment groups. Main outcome was analysis of the time to viral rebound (>5,000 copies/ml) during the open-ended TI. Secondary outcomes included study-defined safety criteria, viral resistance, therapy failure, and retention of immune reconstitution.There was no difference between the groups in time to viral rebound during the open-ended TI (continuous therapy/single TI, median [interquartile range] = 4 [1–8] wk, n = 21; repeated TI, median [interquartile range] = 5 [4–8] wk, n = 21; p = 0.36). No differences in study-related adverse events, viral set point at 12 or 20 wk of open-ended interruption, viral resistance or therapy failure, retention of CD4 T cell numbers on ART, or retention of lymphoproliferative recall antigen responses were noted between groups. Importantly, resistance detected shortly after initial viremia following the open-ended TI did not result in a lack of resuppression to less than 50 copies/ml after reinitiation of the same drug regimen.ConclusionCycles of 2- to 6-wk time-fixed TIs in patients with suppressed HIV infection failed to confer a clinically significant benefit with regard to viral suppression off ART. Also, secondary analysis showed no difference between the two strategies in terms of safety, retention of immune reconstitution, and clinical therapy failure. Based on these findings, we suggest that further clinical research on the long-term consequences of TI strategies to decrease drug exposure is warranted.

Long-term persistence of vaccination and HAART to human immunodeficiency virus (HIV)

The aim of this study was to monitor the immune responses in HIV-infected patients previously immunized with gp160 or DNA vaccines to analyze whether the introduction of highly active antiretroviral treatment (HAART) would affect the persistence of immunity. The immune responses were evaluated in patients who had participated in randomized trials of therapeutic vaccination. Immunization in conjunction with antiretroviral therapy was effective in inducing HIV-specific T-cell responses. Therapeutic immunizations with recombinant gp160 had a modest effect on CD4-cell counts, the treatment alone lead to a transient clinical benefit in the form of an improved survival after two years of immunization. Immunizations with HIV DNA during HAART treatment permitted persistence or development of innate (NK), CD4+ and/or CD8+ immune responses. HIV specific T-helper cell responses induced by immunization with gp160 were maintained at high levels up to 7 years after the last injection. Cells with HIV-specific interferon-γ (IFN-γ) production were retained or increased in long-term HAART treated patients. The impact of a single structured therapy interruption (STI) was analyzed in a small group of patients showing no obvious increase or decrease in the HIV-specific immune response during or after STI. The possibility to induce very long-term strong and persistent immune responses in HIV-infected individuals raises hopes that vaccination preceding therapy interruption might prolong the symptom-free period without HAART.

Boosting immunity by antiviral drug therapy: a simple relationship among timing, efficacy, and success.

Drug therapies against persistent human infections such as hepatitis C virus, hepatitis B virus, and HIV fail to consistently eradicate the infection from the host. Hence, recent emphasis has shifted to the study of antiviral therapy aimed at boosting specific immune responses. It was argued that structured therapy interruptions were required to achieve this, because such regimes have shown promising results in early HIV infection. Using mathematical models, we show that, contrary to this notion, a single phase of drug therapy can result in the establishment of sustained immunity. We present a simple relationship between timing of therapy and efficacy of the drugs required for success. In the presence of strong viral suppression, we show that therapy should be stopped relatively early, and that a longer duration of treatment leads to failure. On the other hand, in the presence of weaker viral suppression, stopping treatment too early is detrimental, and therapy has to be continued beyond a time threshold. We discuss our modeling results primarily in the context of HCV therapy during chronic infection. Although the therapy regimes explored here also have implications for HIV, virus-mediated destruction of specific immune cells renders success unlikely during the chronic phase of the infection.

Computer-Based Design of an HLA-Haplotype and HIV-Clade Independent Cytotoxic T-Lymphocyte (CTL) Assay for Monitoring HIV-Specific Immunity

Human immunodeficiency virus (HIV)- specific CD8-positive cytotoxic T-lymphocytes (CTL) play a key role in controlling HIV infection. Monitoring CTL response could be clinically relevant during structured therapy interruption (STI), HIV exposure, and vaccine trials. However, HLA patients' restriction and HIV variability limited the development of a CTL assay with broad specificity. We designed an HLA-class I/HIV-1 clade independent assay for assessing HIV- specific CTL by using a computer-assisted selection ofthe CTL epitopes. Twenty-eight 15-mers were selected by peptide-binding motifs analysis using different databases (HIV-Immunology Database, SYFPEITHI, BIMAS). Altogether they putatively bind to more than 90% of HLA haplotypes in different populations, with an overall HIV-1 variability below 9%. The peptide pool was used as an antigen in an intracellular cytokine staining (ICS) assay for quantifying HIV-specific CTL response. The test can be performed using both fresh and cryopreserved peripheral blood mononuclear cells (PBMC), whereas GAG protein as antigen works only on fresh PBMC. A significantly higher CTL response with respect to HIV-negative controls was detected in all HIV-1 infected subjects of two groups of patients with different ethnicities (Caucasians and Africans) and coming from areas with different HIV-1 clade prevalences (clade B and A/G, respectively). In Caucasian patients, after month of STI, the number of HIV-1 specific CTL (2,896 +/- 2,780 IFN-gamma specific CD8 cells/ml) was significantly higher than that found at enrolment (2,125 +/- 4,426 IFN-gamma specific CD8 cells/ml, p< 0.05). These data indicate that this CTL assay is broadly specific and could represent a useful clinical tool for HIV immunodiagnostic independent of HLA-haplotype and HIV-clade variabilities.

Immunological and virological factors at baseline may predict response to structured therapy interruption in early stage chronic HIV-1 infection.

The objective was to analyse which baseline factors could predict a favourable outcome after structured therapy interruption (STI). Data of three Spanish pilot studies of STI in early stage chronic HIV-1-infected patients were analysed. A set of 37 variables at baseline was used. Plasma and tonsillar tissue viral load (VL), lymphocyte immunophenotyping and proliferative responses (LPR) to mitogens and specific antigens, and HIV-1 specific cytotoxic T lymphocyte responses were assessed at baseline. Response was defined as a VL set-point after 6 months off antiretroviral therapy after the last interruption of < 5000 copies/ml and 0.5 log(10) below baseline PVL before any antiretroviral therapy. After STI, the 44 patients were classified as follows: 18 (41%) as responders, 26 (59%) as non-responders. In the univariate analysis patients who responded had a significantly lower baseline level of CD4CD38 (P = 0.0068) and naive CD4 T cells (P = 0.03), and a higher level of memory CD4 T cells (P = 0.03) and proliferative response to tetanus toxoid (TT) (P = 0.01) and HIV-1 p24 (P = 0.03) than non-responders. A model incorporating five qualitative variables transformed according to the median value (CD4CD38, CD4 naive and memory T cells and stimulation index to TT and HIV-1 p24) at baseline could classify 97% of patients correctly (P = 0.0001). A level of memory CD4 T cells and proliferative response to recall antigens above the median may predict a good response to STI, suggesting that preserved memory response in CD4 T cells is important factor.

HIV preferentially infects HIV-specific CD4+ T cells.

HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production. A central, yet unresolved issue of HIV disease is the mechanism for this loss, and in particular whether HIV-specific CD4(+) T cells are preferentially affected. Here we show that HIV-specific memory CD4(+) T cells in infected individuals contain more HIV viral DNA than other memory CD4(+) T cells, at all stages of HIV disease. Additionally, following viral rebound during interruption of antiretroviral therapy, the frequency of HIV viral DNA in the HIV-specific pool of memory CD4(+) T cells increases to a greater extent than in memory CD4(+) T cells of other specificities. These findings show that HIV-specific CD4(+) T cells are preferentially infected by HIV in vivo. This provides a potential mechanism to explain the loss of HIV-specific CD4(+) T-cell responses, and consequently the loss of immunological control of HIV replication. Furthermore, the phenomenon of HIV specifically infecting the very cells that respond to it adds a cautionary note to the practice of structured therapy interruption.

An in vivo model for HIV resistance development.

Treatment of human immunodeficiency virus (HIV-1) with drugs targeted to the reverse transcriptase (RT) rapidly selects for drug-resistant virus. It is essential to develop a suitable animal model that allows the study of the emergence and reversal of drug resistance. A monkey model was previously developed on the basis of a hybrid virus (RT-SHIV) of simian immunodeficiency virus (SIV) with its RT exchanged for HIV-1 RT. In the present study cynomolgus monkeys infected with RT-SHIV were treated with varying doses of the non-nucleoside RT inhibitor nevirapine. The drug was administered for 2-3 weeks, in agreement with clinical experience of resistance development during nevirapine monotherapy. This resulted in the selection of mutants with Y181C and K103N changes in RT, which correspond to the HIV-1 mutations in nevirapine-resistant HIV-1 patients. The mutants coexisted at varying levels with wild-type virus and fluctuations in the proportion of mutants could be closely monitored. Low-dose treatment was not more efficient in induction of mutations than a virus-inhibiting dose. Structured therapy interruptions could be performed. The monkey RT-SHIV infection offers an in vivo model to determine effects of therapies on resistance development.

Risks and benefits of structured antiretroviral drug therapy interruptions in HIV-1 infection.

Structured interruptions of antiretroviral therapy of HIV-1 infected individuals are currently being tested in clinical trials to study the effect interruptions have on the immune responses and control of virus replication. To investigate the potential risks and benefits of interrupted therapy using standard population dynamical models of HIV replication kinetics. Standard population dynamical models were used to study the effect of structured therapy interruptions on the immune effector cells, the latent cell compartment and the emergence of drug resistance. The models suggest that structured therapy interruption only leads to transient or sustained virus control if the immune effector cells increase during therapy. This increase must more than counterbalance the increase in susceptible target cells induced by therapy. The risk of inducing drug resistance by therapy interruptions or the risk of repopulating the pool of latent cells during drug-free periods may be small if the virus population remains at levels considerably below baseline. However, if the virus load increases during drug-free periods to levels similar to or higher than baseline before therapy, both these risks increase dramatically.

HAART stopping news: experts examine structured therapy interruption for HIV.

behavior of HIV in the presence of HAART. It is quite clear, he said, that even when someone is successfully treated with HAART, the virus continues to replicate at a very low rate. This undetectable virus allows for the rebound of plasma viremia in virtually all patients when therapy is stopped or suspended.