A phase I, randomized study of combined IL-2 and therapeutic immunisation with antiretroviral therapy

HIV-1 Immunogen: an overview of almost 30 years of clinical testing of a candidate therapeutic vaccine

INTRODUCTION

Although current antiretroviral therapy (ART) has transformed HIV infection into a chronic, manageable disease, ART does not cure HIV infection. Furthermore, the majority of the world's infected individuals live in resource-limited countries in which access to ART is limited. Thus, the development of an effective therapeutic HIV vaccine would be an invaluable treatment alternative.

AREAS COVERED

Developed by the late Dr. Jonas Salk, HIV-1 Immunogen (Remune®) is a candidate therapeutic vaccine that has been studied in thousands of HIV-infected individuals in more than a dozen clinical trials during almost three decades. This Drug Evaluation, which summarizes the results of these trials that have shown the vaccine to be safe and immunogenic, also discusses the contradictory and controversial conclusions drawn from the phases 2, 2/3 and 3 trials that assessed the clinical efficacy of this vaccine.

EXPERT OPINION

Given the lack of unequivocal clinical benefits of HIV-1 Immunogen despite almost 30 years of extensive testing, it does not appear, in our view, that this vaccine is a clinically effective immunotherapy. However, inclusion of this vaccine in the newly proposed 'Kick/Shock and Kill' strategy for HIV eradication, or use as a prophylactic vaccine, could be considered for future trials.

A piecewise model of virus-immune system with two thresholds

The combined antiretroviral therapy with interleukin (IL)-2 treatment may not be enough to preclude exceptionally high growth of HIV virus nor rebuilt the HIV-specific CD4 or CD8 T-cell proliferative immune response for management of HIV infected patients. Whether extra inclusion of immune therapy can induce the HIV-specific immune response and control HIV replication remains challenging. Here a piecewise virus-immune model with two thresholds is proposed to represent the HIV-1 RNA and effector cell-guided therapy strategies. We first analyze the dynamics of the virus-immune system with effector cell-guided immune therapy only and prove that there exists a critical level of the intensity of immune therapy determining whether the HIV-1 RAN virus loads can be controlled below a relative low level. Our analysis of the global dynamics of the proposed model shows that the pseudo-equilibrium can be globally stable or locally bistable with order 1 periodic solution or bistable with the virus-free periodic solution under various appropriate conditions. This indicates that HIV viral loads can either be eradicated or stabilize at a previously given level or go to infinity (corresponding to the effector cells oscillating), depending on the threshold levels and the initial HIV virus loads and effector cell counts. Comparing with the single threshold therapy strategy we obtain that with two thresholds therapy strategies either virus can be eradicated or the controllable region, where HIV viral loads can be maintained below a certain value, can be enlarged.

HIV-Tat immunization induces cross-clade neutralizing antibodies and CD4(+) T cell increases in antiretroviral-treated South African volunteers: a randomized phase II clinical trial

BACKGROUND

Although combined antiretroviral therapy (cART) has saved millions of lives, it is incapable of full immune reconstitution and virus eradication. The transactivator of transcription (Tat) protein is a key human immunodeficiency virus (HIV) virulence factor required for virus replication and transmission. Tat is expressed and released extracellularly by infected cells also under cART and in this form induces immune dysregulation, and promotes virus reactivation, entry and spreading. Of note, anti-Tat antibodies are rare in natural infection and, when present, correlate with asymptomatic state and reduced disease progression. This suggested that induction of anti-Tat antibodies represents a pathogenesis-driven intervention to block progression and to intensify cART. Indeed Tat-based vaccination was safe, immunogenic and capable of immune restoration in an open-label, randomized phase II clinical trial conducted in 168 cART-treated volunteers in Italy. To assess whether B-clade Tat immunization would be effective also in patients with different genetic background and infecting virus, a phase II trial was conducted in South Africa.

METHODS

The ISS T-003 was a 48-week randomised, double-blinded, placebo-controlled trial to evaluate immunogenicity (primary endpoint) and safety (secondary endpoint) of B-clade Tat (30 μg) given intradermally, three times at 4-week intervals, in 200 HIV-infected adults on effective cART (randomised 1:1) with CD4(+) T-cell counts ≥200 cells/µL. Study outcomes also included cross-clade anti-Tat antibodies, neutralization, CD4(+) T-cell counts and therapy compliance.

RESULTS

Immunization was safe and well-tolerated and induced durable, high titers anti-Tat B-clade antibodies in 97 % vaccinees. Anti-Tat antibodies were cross-clade (all vaccinees tested) and neutralized Tat-mediated entry of oligomeric B-clade and C-clade envelope in dendritic cells (24 participants tested). Anti-Tat antibody titers correlated positively with neutralization. Tat vaccination increased CD4(+) T-cell numbers (all participants tested), particularly when baseline levels were still low after years of therapy, and this had a positive correlation with HIV neutralization. Finally, in cART non-compliant patients (24 participants), vaccination contained viral load rebound and maintained CD4(+) T-cell numbers over study entry levels as compared to placebo.

CONCLUSIONS

The data indicate that Tat vaccination can restore the immune system and induces cross-clade neutralizing anti-Tat antibodies in patients with different genetic backgrounds and infecting viruses, supporting the conduct of phase III studies in South Africa. Trial registration ClinicalTrials.gov NCT01513135, 01/23/2012.

Multifarious immunotherapeutic approaches to cure HIV-1 infection

Immunotherapy in the context of treated HIV-1 infection aims to improve immune responses to achieve better control of the virus. To date, multifaceted immunotherapeutic approaches have been shown to reduce immune activation and increase CD4 T-lymphocyte counts, further to the effects of antiretroviral therapy alone, in addition to improving HIV-1-specific T-cell responses. While sterilizing cure of HIV-1 would involve elimination of all replication-competent virus, a functional cure in which the host has long-lasting control of viral replication may be more feasible. In this commentary, we discuss novel strategies aimed at targeting the latent viral reservoir with cure of HIV-1 infection being the ultimate goal, an achievement that would have considerable impact on worldwide HIV-1 infection.

Therapeutic immunisation plus cytokine and hormone therapy improves CD4 T-cell counts, restores anti-HIV-1 responses and reduces immune activation in treated chronic HIV-1 infection

BACKGROUND

This randomised, open label, phase I, immunotherapeutic study investigated the effects of interleukin (IL)-2, granulocyte-macrophage colony-stimulating factor (GM-CSF), recombinant human growth hormone (rhGH), and therapeutic immunisation (a Clade B DNA vaccine) on combination antiretroviral therapy (cART)-treated HIV-1-infected individuals, with the objective to reverse residual T-cell dysfunction.

METHODS

Twelve HIV-1(+) patients on suppressive cART with baseline CD4 T-cell counts >400 cells/mm(3) blood were randomised into one of three groups: (1) vaccine, IL-2, GM-CSF and rhGH (n=3); (2) vaccine alone (n=4); or (3) IL-2, GM-CSF and rhGH (n=5). Samples were collected at weeks 0, 1, 2, 4, 6, 8, 12, 16, 24 and 48. Interferon (IFN)-γ, IL-2, IL-4 and perforin ELISpot assays performed at each time point quantified functional responses to Gag p17/p24, Nef, Rev, and Tat peptides; and detailed T-cell immunophenotyping was undertaken by flow cytometry. Proviral DNA was also measured.

RESULTS

Median baseline CD4 T-cell count was 757 cells/mm(3) (interquartile range [IQR] 567-886 cells/mm(3)), median age 48 years (IQR 42-51 years), and plasma HIV-1-RNA <50 copies/ml for all subjects. Patients who received vaccine plus IL-2, GM-CSF and rhGH (group 1) showed the most marked changes. Assessing mean changes from baseline to week 48 revealed significantly elevated numbers of CD4 T cells (p=0.0083) and improved CD4/CD8 T-cell ratios (p=0.0033). This was accompanied by a significant reduction in expression of CD38 on CD4 T cells (p=0.0194), significantly increased IFN-γ and IL-2 production in response to Gag (p=0.0122) and elevated IFN-γ production in response to Tat (p=0.041) at week 48 compared to baseline. Subjects in all treatment groups showed significantly reduced PD-1 expression at week 48 compared to baseline, with some reductions in proviral DNA.

CONCLUSIONS

Multifarious immunotherapeutic approaches in the context of fully suppressive cART further reduce immune activation, and improve both CD4 T-lymphocyte counts and HIV-1-specific T-cell responses (NCT01130376).

Low-dose growth hormone for 40 weeks induces HIV-1-specific T cell responses in patients on effective combination anti-retroviral therapy

Recombinant human growth hormone (rhGH) administered to combination anti-retroviral therapy (cART)-treated human immunodeficiency virus-1 (HIV-1)-infected individuals has been found to reverse thymic involution, increase total and naive CD4 T cell counts and reduce the expression of activation and apoptosis markers. To date, such studies have used high, pharmacological doses of rhGH. In this substudy, samples from treated HIV-1(+) subjects, randomized to receive either a physiological dose (0·7 mg) of rhGH (n = 21) or placebo (n = 15) daily for 40 weeks, were assessed. Peptide-based enzyme-linked immunospot (ELISPOT) assays were used to enumerate HIV-1-specific interferon (IFN)-γ-producing T cells at baseline and week 40. Individuals who received rhGH demonstrated increased responses to HIV-1 Gag overlapping 20mer and Gag 9mer peptide pools at week 40 compared to baseline, whereas subjects who received placebo showed no functional changes. Subjects with the most robust responses in the ELISPOT assays had improved thymic function following rhGH administration, as determined using CD4(+) T cell receptor rearrangement excision circle (TREC ) and thymic density data from the original study. T cells from these robust responders were characterized further phenotypically, and showed decreased expression of activation and apoptosis markers at week 40 compared to baseline. Furthermore, CD4 and CD8 T cell populations were found to be shifted towards an effector and central memory phenotype, respectively. Here we report that administration of low-dose rhGH over 40 weeks with effective cART resulted in greater improvement of T lymphocyte function than observed with cART alone, and provide further evidence that such an approach could also reduce levels of immune activation.

PD-L1 blockade synergizes with IL-2 therapy in reinvigorating exhausted T cells

The inhibitory receptor programmed cell death 1 (PD-1) plays a major role in functional exhaustion of T cells during chronic infections and cancer, and recent clinical data suggest that blockade of the PD-1 pathway is an effective immunotherapy in treating certain cancers. Thus, it is important to define combinatorial approaches that increase the efficacy of PD-1 blockade. To address this issue, we examined the effect of IL-2 and PD-1 ligand 1 (PD-L1) blockade in the mouse model of chronic lymphocytic choriomeningitis virus (LCMV) infection. We found that low-dose IL-2 administration alone enhanced CD8+ T cell responses in chronically infected mice. IL-2 treatment also decreased inhibitory receptor levels on virus-specific CD8+ T cells and increased expression of CD127 and CD44, resulting in a phenotype resembling that of memory T cells. Surprisingly, IL-2 therapy had only a minimal effect on reducing viral load. However, combining IL-2 treatment with blockade of the PD-1 inhibitory pathway had striking synergistic effects in enhancing virus-specific CD8+ T cell responses and decreasing viral load. Interestingly, this reduction in viral load occurred despite increased numbers of Tregs. These results suggest that combined IL-2 therapy and PD-L1 blockade merits consideration as a regimen for treating human chronic infections and cancer.

Functional expression of secreted proteins from a bicistronic retroviral cassette based on foot-and-mouth disease virus 2A can be position dependent

The expression of two or more genes from a single viral vector has been widely used to label or select for cells containing the transgenic element. Identification of the foot-and-mouth disease virus (FMDV) 2A cleavage peptide as a polycistronic linker capable of producing equivalent levels of transgene expression has greatly improved this approach in the field of gene therapy. However, as a consequence of 2A posttranslational cleavage the upstream protein is left with a residual 19 amino acids from the 2A sequence on its carboxy terminus, and the downstream protein is left with an additional 2 to 5 amino acids on its amino terminus. Here we have assessed the functional consequences of the FMDV 2A cleavage motif on two secreted proteins (interleukin [IL]-2 and transforming growth factor [TGF]-β) when expressed from a retroviral bicistronic vector. Whereas IL-2 expression and function were found to be unaffected by the 2A motif in either orientation, functional expression of secreted TGF-β was significantly abrogated when the transgene was expressed upstream of the 2A sequence. We believe this is a consequence of aberrant cleavage and intracellular trafficking of the TGF-β polyprotein. These results highlight that to achieve functional expression of secreted proteins consideration must be taken of the transgenic protein's posttranslational modification and trafficking when using 2A-based bicistronic cassettes.

Therapeutic immunization in HIV infected Ugandans receiving stable antiretroviral treatment: a Phase I safety study

Therapeutic immunizations in HIV infection may boost immunity during antiretroviral treatment. We report on the first therapeutic vaccine trial in Uganda, Africa. This open label Phase I trial was designed to assess the safety, tolerability and immunogenicity of a therapeutic HIV-1 vaccine candidate. Thirty HIV positive volunteers receiving a stable regimen of antiretroviral therapy with CD4 counts >400 were recruited for the safety evaluation of LFn-p24C, a detoxified anthrax-derived polypeptide fused to the subtype C HIV gag protein p24. The vaccine was well tolerated and HIV RNA levels remained undetectable following three immunizations. CD4 counts in vaccine recipients were significantly higher compared to the control individuals after 12 months. HIV-specific responses were associated with higher gain in CD4 counts following LFn-p24C immunizations. Volunteers were subsequently asked to undergo a 30-day period of observed treatment interruption. 8/24 (30%) individuals showed no evidence of viral rebound during treatment interruption. All demonstrated prompt suppression of viral load following resumption of ART. Our data demonstrate the safety of LFn-p24C and suggest that adjunct therapeutic immunization may benefit select individuals in further boosting an immune response.

A tonsillar PolyICLC/AT-2 SIV therapeutic vaccine maintains low viremia following antiretroviral therapy cessation

BACKGROUND

HIV-infected individuals rely on antiretroviral therapy (ART) to control viral replication. Despite abundant demonstrable benefits, the multiple limitations of ART point to the potential advantages of therapeutic vaccination approaches that could provide sustained host control of viral replication after discontinuation of ART. We provide evidence from a non-human primate model that a therapeutic vaccine applied to the tonsils can maintain low viral loads after cessation of ART.

METHODOLOGY/PRINCIPAL FINDINGS

Animals received 40 weeks of ART initiated 9 weeks after rectal SIVmac239 infection. During ART, animals were vaccinated (or not) with AT-2 inactivated SIVmac239 using CpG-C ISS-ODN (C274) or polyICLC as adjuvants. PolyICLC/AT-2 SIV vaccinated animals maintained viral loads <3×10(3) copies/ml for up to 16 weeks post-ART, whereas the C274/AT-2 SIV vaccinated and non-vaccinated animals' viremia ranged between 1×10(4)-4×10(5) copies/ml (p<0.03). Neutralizing Ab activity in plasma was increased by polyICLC/AT-2 tonsillar vaccination under ART, compared to controls (p<0.03). Subsequent vaccination of all animals with polyICLC/AT-2 SIV in the absence of ART did not alter viral loads. Other immune parameters measured in blood and tissues were comparable between groups.

CONCLUSIONS/SIGNIFICANCE

These results provide support for the potential benefit of mucosally delivered vaccines in therapeutic immunization strategies for control of AIDS virus infection.

Immunotherapy of viral infections

Among the microorganisms that cause diseases of medical or veterinary importance, the only group that is entirely dependent on the host, and hence not easily amenable to therapy via pharmaceuticals, is the viruses. Since viruses are obligate intracellular pathogens, and therefore depend a great deal on cellular processes, direct therapy of viral infections is difficult. Thus, modifying or targeting nonspecific or specific immune responses is an important aspect of intervention of ongoing viral infections. However, as a result of the unavailability of effective vaccines and the extended duration of manifestation, chronic viral infections are the most suitable for immunotherapies. We present an overview of various immunological strategies that have been applied for treating viral infections after exposure to the infectious agent.

Repeated DNA therapeutic vaccination of chronically SIV-infected macaques provides additional virological benefit

We have previously reported that therapeutic immunization by intramuscular injection of optimized plasmid DNAs encoding SIV antigens effectively induces immune responses able to reduce viremia in antiretroviral therapy (ART)-treated SIVmac251-infected Indian rhesus macaques. We subjected such therapeutically immunized macaques to a second round of therapeutic vaccination using a combination of plasmids expressing SIV genes and the IL-15/IL-15 receptor alpha as molecular adjuvant, which were delivered by the more efficacious in vivo constant-current electroporation. A very strong induction of antigen-specific responses to Gag, Env, Nef, and Pol, during ART (1.2-1.6% of SIV-specific T cells in the circulating T lymphocytes) was obtained with the improved vaccination method. Immunological responses were characterized by the production of IFN-gamma, IL-2, and TNF-alpha either alone, or in combination as double or triple cytokine positive multifunctional T cells. A significant induction of CD4(+) T cell responses, mainly targeting Gag, Nef, and Pol, as well as of CD8(+) T cells, mainly targeting Env, was found in both T cells with central memory and effector memory markers. After release from ART, the animals showed a virological benefit with a further approximately 1 log reduction in viremia. Vaccination with plasmid DNAs has several advantages over other vaccine modalities, including the possibility for repeated administration, and was shown to induce potent, efficacious, and long-lasting recall immune responses. Therefore, these data support the concept of adding DNA vaccination to the HAART regimen to boost the HIV-specific immune responses.

Programmed death (PD)-1 molecule and its ligand PD-L1 distribution among memory CD4 and CD8 T cell subsets in human immunodeficiency virus-1-infected individuals

Human immunodeficiency virus (HIV)-1 causes T cell anergy and affects T cell maturation. Various mechanisms are responsible for impaired anti-HIV-1-specific responses: programmed death (PD)-1 molecule and its ligand PD-L1 are negative regulators of T cell activity and their expression is increased during HIV-1 infection. This study examines correlations between T cell maturation, expression of PD-1 and PD-L1, and the effects of their blockade. Peripheral blood mononuclear cells (PBMC) from 24 HIV-1(+) and 17 uninfected individuals were phenotyped for PD-1 and PD-L1 expression on CD4(+) and CD8(+) T cell subsets. The effect of PD-1 and PD-L1 blockade on proliferation and interferon (IFN)-gamma production was tested on eight HIV-1(+) patients. Naive (CCR7(+)CD45RA(+)) CD8(+) T cells were reduced in HIV-1 aviraemic (P = 0.0065) and viraemic patients (P = 0.0130); CD8 T effector memory subsets [CCR7(-)CD45RA(-)(T(EM))] were increased in HIV-1(+) aviraemic (P = 0.0122) and viraemic (P = 0.0023) individuals versus controls. PD-1 expression was increased in CD4 naive (P = 0.0496), central memory [CCR7(+)CD45RA(-) (T(CM)); P = 0.0116], T(EM) (P = 0.0037) and CD8 naive T cells (P = 0.0133) of aviraemic HIV-1(+) versus controls. PD-L1 was increased in CD4 T(EMRA) (CCR7(-)CD45RA(+), P = 0.0119), CD8 T(EM) (P = 0.0494) and CD8 T(EMRA) (P = 0.0282) of aviraemic HIV-1(+)versus controls. PD-1 blockade increased HIV-1-specific proliferative responses in one of eight patients, whereas PD-L1 blockade restored responses in four of eight patients, but did not increase IFN-gamma-production. Alteration of T cell subsets, accompanied by increased PD-1 and PD-L1 expression in HIV-1 infection contributes to anergy and impaired anti-HIV-1-specific responses which are not rescued when PD-1 is blocked, in contrast to when PD-L1 is blocked, due possibly to an ability to bind to receptors other than PD-1.

Manipulating both the inhibitory and stimulatory immune system towards the success of therapeutic vaccination against chronic viral infections

SUMMARY

One potentially promising strategy to control chronic infections such as human immunodeficiency virus, hepatitis B virus, and hepatitis C virus is therapeutic vaccination, which aims to reduce persisting virus by stimulating a patient's own antiviral immune responses. However, this approach has fallen short of expectations, because antiviral T cells generated during chronic infections often become functionally exhausted and thus do not respond properly to therapeutic vaccination. Therefore, it is necessary to develop a therapeutic vaccine strategy to more effectively boost endogenous T-cell responses to control persistent viral infections. Studies to elucidate the cause of impaired T-cell function have pointed to sustained inhibitory receptor signaling through T-cell expression of programmed death 1 (PD-1). Recently, another inhibitory molecule, cytotoxic T lymphocyte antigen 4 (CTLA-4), and also an immunosuppressive cytokine, interleukin 10 (IL-10), have been reported to be potential factors of establishing immune suppression and viral persistence. Blocking these negative signaling pathways could restore the host immune system, enabling it to respond to further stimulation. Indeed, combining therapeutic vaccination along with the blockade of inhibitory signals could synergistically enhance functional CD8(+) T-cell responses and improve viral control in chronically infected mice, providing a promising strategy for the treatment of chronic viral infections. Furthermore, not only the ablation of negative signals but also the addition of stimulatory signals, such as interleukin 2 (IL-2), might prove to be a potentially promising strategy to augment the efficacy of therapeutic vaccination against chronic viral infections.

Long-term increase of CD4+ central memory cells in HIV-1-infected individuals by therapeutic HIV-1 rgp160 immunization

OBJECTIVE

To evaluate functional potential and phenotypic markers in HIV-1-infected patients immunized with HIV-1 rgp160.

METHODS

We assessed changes in T-cell phenotype and immune function in 12 HIV-1-infected individuals that were part of a therapeutic vaccine study from 1992 to 1995 [Sandstrom E, Wahren B. Therapeutic immunisation with recombinant gp160 in HIV-1 infection: a randomised double-blind placebo-controlled trial. Nordic VAC-04 Study Group. Lancet 1999;353(9166):1735-42]. The patients received 160 microg HIV-1 rgp160 or placebo i.m. at baseline (day 0), and months 1, 2, 3, 4, 6, and thereafter every 3 months. Frozen peripheral blood mononuclear cells (PBMC) were retrieved from time points 0, 9, 12 and 24 months for phenotypic analysis utilizing flow cytometry.

RESULTS

Up-regulation of immune activation markers HLA-DR and CD38 was observed at baseline and throughout the monitoring period on both CD4+ and CD8+ T cells in all patients, reflecting immune activation due to persistent high viral load. Further enhanced expression of activation markers was observed over time in the vaccine group, but not the placebo group. We also observed a consistent long-term increase of the CD4+ central memory population (CD3+CD4+CD45RA-CCR7+) in the vaccinated group.

CONCLUSIONS

Administration of eight doses of rgp160 in a year appeared to partially reverse some of the defects exerted by HIV-1 on the immune system. A combination of vaccination with effective antiretroviral therapy (ART) may thus represent an immunotherapeutic intervention for treatment of chronic HIV-1 infection. The improvement of a HIV-1-specific central memory population and HIV-1 antigen-specific CD4+ lymphoproliferative responses may have contributed to the short-term improved survival reported in the vaccinated group.

Immunization with an HIV-1 immunogen induces CD4+ and CD8+ HIV-1-specific polyfunctional responses in patients with chronic HIV-1 infection receiving antiretroviral therapy

Development of polyfunctional T lymphocyte responses is critical in the immunological response against HIV-1. Fifty-four HIV-1 infected patients receiving antiretroviral treatment (ART) and immunization with an HIV-1 immunogen or placebo, periodically every 3 months throughout a period of 36 months, were evaluated for the purposes of analysing the development of HIV-1-specific CD4+ and CD8+ responses. A significant increase of proliferating and IFN-gamma producing CD8+ HIV-1-specific T cells, of HIV-1-specific precursor frequencies for CD8+ and for CD4+ T cells and of Gag/pol-specific memory CTL precursors (CTLp) was observed in the immunogen group in comparison to placebo. IL-2 intracellular expression and IFN-gamma and TNF-alpha co-expression in HIV-1-specific CD8+ T cells were also substantially increased in the immunized group. A negative correlation between viral load and CD3+CD4+CFSElow HIV-1-specific lymphoproliferative response and frequency of Gag/pol-specific CTLp was solely observed in the HIV-1 immunogen group. Long-term immunization in patients receiving ART helps to develop HIV-1-specific polyfunctional T cell responses.

Combined use of cytokines, hormones and therapeutic vaccines during effective antiretroviral therapy

Immune-based therapies using vaccines, cytokines and hormones are being considered in the context of effective antiretroviral therapy to induce immunologically defined long-term nonprogressor status in chronically infected HIV-1 patients. Such immunotherapy must allow induction or regeneration of anti-HIV-1 immune responses with the potential to control viremia, activate and eradicate viral reservoirs, and alleviate the immunosuppression caused by HIV-1, eventually possibly reaching the status of a virologically defined ‘elite controller’ with an absence of detectable viremia and no progression to disease over a long period of time. This article summarizes pilot studies utilizing therapeutic vaccines, cytokines and/or hormones in treated HIV-1 infection, and focuses on novel agents and immunotherapeutic options that may have the potential to augment or replace existing antiretroviral therapy with the aim of inducing nonprogressor status in the infected host.