Dendritic Cell Immunotherapy for HIV-1 Infection Using Autologous HIV-1 RNA: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Immunogenicity of AGS-004 Dendritic Cell Therapy in Patients Treated During Acute HIV Infection

AGS-004 consists of matured autologous dendritic cells co-electroporated with in vitro transcribed RNA encoding autologous HIV antigens. In an open-label, single arm sub-study of AGS-004-003, AGS-004 was administered monthly to suppressed participants who started antiretroviral therapy (ART) during acute HIV infection. HIV-1 specific T cell responses were measured by multicolor flow cytometry after 3-4 doses. The frequency of resting CD4⁺ T-cell infection (RCI) was measured by quantitative viral outgrowth assay. Participants demonstrating increased immune response postvaccination were eligible for analytic treatment interruption (ATI). AGS-004 induced a positive immune response defined as ≥2-fold increase from baseline in the number of multifunctional HIV-1 specific CD28⁺/CD45RA^- CD8⁺ effector/memory cytoxic T-lymphocytes (CTLs) in all six participants. All participants underwent ATI with rebound viremia at a median of 29 days. Immune correlates between time to viral rebound and the induction of effector CTLs were determined. Baseline RCI was low in most participants (0.043-0.767 IUPM). One participant had a >2-fold decrease (0.179-0.067 infectious units per million [IUPM]) in RCI at week 10. One participant with the lowest RCI had the longest ATI. AGS-004 dendritic cell administration increased multifunctional HIV-specific CD28⁺/CD45RA^- CD8⁺ memory T cell responses in all participants, but did not permit sustained ART interruption. However, greater expansion of CD28^-/CCR7^-/CD45RA^- CD8⁺ effector T cell responses correlated with a longer time to viral rebound. AGS-004 may be a useful tool to augment immune responses in the setting of latency reversal and eradication strategies.

Genome-wide scan in two groups of HIV-infected patients treated with dendritic cell-based immunotherapy

We performed a retrospective genome-wide association study in HIV-infected individuals who were treated with dendritic cell-based immunotherapy in clinical trials performed by two research groups (Spain and Brazil). We aimed to identify host genetic variants influencing treatment response. The Illumina Human Core Exome 12 v 1.0 Bead Chip with over 250,000 markers was used to analyze genetic factors affecting treatment response. Additionally, we performed a meta-analysis of the results obtained from Spanish and Brazilian patients. We identified a genetic variation (rs7935564 G allele) in TRIM22 gene, which encodes TRIM22 protein acting like a HIV restriction factor, as being associated with good response to dendritic cell-based immunotherapy. We then verified the impact of TRIM22 rs7935564 SNP in susceptibility to HIV infection and disease progression by assessing the influence of biogeographic ancestry in the distribution of allelic and genotype frequencies in three populations from Italy, Brazil and Zambia. TRIM22 rs7935564 genotyping indicated association of G rs7935564 allele with long-term non-progression of HIV disease in Italian patients, thus corroborating our hypothesis that it is involved as a restriction factor in dendritic cell-based immunotherapy response. TRIM22 rs7935564 polymorphism was associated with good response to dendritic cell-based immunotherapy. We hypothesize that in selecting patients for treatment, there is a possible bias related to the natural presence of restriction factors that are genetically determined and could influence final outcome of therapy.

A randomized controlled safety/efficacy trial of therapeutic vaccination in HIV-infected individuals who initiated antiretroviral therapy early in infection

Despite substantial clinical benefits, complete eradication of HIV has not been possible using antiretroviral therapy (ART) alone. Strategies that can either eliminate persistent viral reservoirs or boost host immunity to prevent rebound of virus from these reservoirs after discontinuation of ART are needed; one possibility is therapeutic vaccination. We report the results of a randomized, placebo-controlled trial of a therapeutic vaccine regimen in patients in whom ART was initiated during the early stage of HIV infection and whose immune system was anticipated to be relatively intact. The objectives of our study were to determine whether the vaccine was safe and could induce an immune response that would maintain suppression of plasma viremia after discontinuation of ART. Vaccinations were well tolerated with no serious adverse events but produced only modest augmentation of existing HIV-specific CD4+ T cell responses, with little augmentation of CD8+ T cell responses. Compared with placebo, the vaccination regimen had no significant effect on the kinetics or magnitude of viral rebound after interruption of ART and no impact on the size of the HIV reservoir in the CD4+ T cell compartment. Notably, 26% of subjects in the placebo arm exhibited sustained suppression of viremia (<400 copies/ml) after treatment interruption, a rate of spontaneous suppression higher than previously reported. Our findings regarding the degree and kinetics of plasma viral rebound after ART interruption have potentially important implications for the design of future trials testing interventions aimed at achieving ART-free control of HIV infection.

Cell-Mediated Immune Predictors of Vaccine Effect on Viral Load and CD4 Count in a Phase 2 Therapeutic HIV-1 Vaccine Clinical Trial

Background

In a placebo-controlled trial of the peptide-based therapeutic HIV-1 p24^Gag vaccine candidate Vacc-4x, participants on combination antiretroviral therapy (cART) received six immunizations over 18 weeks, followed by analytical treatment interruption (ATI) between weeks 28 and 52. Cell-mediated immune responses were investigated as predictors of Vacc-4x effect (VE) on viral load (VL) and CD4 count during ATI.

Methods

All analyses of week 28 responses and fold-changes relative to baseline considered per-protocol participants (Vacc-4x:placebo = 72:32) resuming cART after week 40. Linear regression models with interaction tests were used. VE was estimated as the Vacc-4x–placebo difference in log₁₀-transformed VL (VE^VL) or CD4 count (VE^CD4).

Findings

A lower fold-change of CD4+ T-cell proliferation was associated with VE^CD4 at week 48 (p = 0.036, multiplicity adjusted q = 0.036) and week 52 (p = 0.040, q = 0.080). A higher fold-change of IFN-γ in proliferation supernatants was associated with VE^VL at week 44 (p = 0.047, q = 0.07). A higher fold-change of TNF-α was associated with VE^VL at week 44 (p = 0.045, q = 0.070), week 48 (p = 0.028, q = 0.070), and week 52 (p = 0.037, q = 0.074). A higher fold-change of IL-6 was associated with VE^VL at week 48 (p = 0.017, q = 0.036). TNF-α levels (> median) were associated with VE^CD4 at week 48 (p = 0.009, q = 0.009).

Interpretation

These exploratory analyses highlight the potential value of investigating biomarkers in T-cell proliferation supernatants for VE in clinical studies.

•

Ex vivo CD4+ T-cell proliferation was predictive of Vacc-4x effect.

•

IFN-γ, TNF-α and IL-6 secretion in T-cell proliferation supernatants were predictive of Vacc-4x effect.

•

Such immune predictors could be utilized to mitigate risks associated with cART interruption towards HIV cure.

No immune correlates or predictors of therapeutic vaccine effect (i.e. a reduction in viral load compared to placebo on treatment interruption) for human immunodeficiency virus (HIV)-1 are known. We investigated a broad array of cytokines/chemokines produced in T-cell proliferation supernatants from a placebo-controlled clinical study of a therapeutic HIV vaccine. Although such supernatants do not provide cell type-specific readouts, the cytokines/chemokines studied included T-helper (Th)1, Th2, growth factor, immuno-modulatory and pro-inflammatory functions. Specifically, we found that, IFN-γ, TNF-α and IL-6 secretion correlated with vaccine effect, suggesting such supernatants could represent important sample material not previously considered for the identification of immune markers of vaccine effect.

Therapeutic vaccines and immunological intervention in HIV infection: a paradigm change

PURPOSE OF REVIEW

The purpose is to review current knowledge of immunological interventions in HIV infection and discuss strategies for the establishment of functional cure and/or HIV eradication.

RECENT FINDINGS

Therapeutic vaccines and cytokines have been historically the immunological interventions developed with the objective to enhance the HIV-specific cell-mediated immune responses and to suppress virus replication. Both these interventions have shown only partial antiviral effects. The recent identification and generation of human broad neutralizing antibodies provides potent immunological intervention associated with effective suppression of virus replication in the absence of antiretroviral therapy. Furthermore, the identification that the major HIV cell reservoir containing replication competent and infectious virus is composed by programed cell death protein 1 (PD-1) positive memory CD4 T cells offers the opportunity to target directly the HIV cell reservoir with anti-PD-1 antibodies. Anti-PD-1 antibody therapy may be also critical to prevent exhaustion of CD8 T cells.

SUMMARY

The availability of a diverse armamentarium of immunological intervention offers the opportunity to investigate the efficacy of the combined use of different immunological interventions in inducing prolonged virus suppression in the absence of antiretroviral therapy and functional cure HIV or HIV eradication.

New challenges in therapeutic vaccines against HIV infection

INTRODUCTION

There is a growing interest in developing curative strategies for HIV infection. Therapeutic vaccines are one of the most promising approaches. We will review the current knowledge and the new challenges in this research field. Areas covered: PubMed and ClinicalTrial.gov databases were searched to review the progress and prospects for clinical development of immunotherapies aimed to cure HIV infection. Dendritic cells (DC)-based vaccines have yielded the best results in the field. However, major immune-virologic barriers may hamper current vaccine strategies. We will focus on some new challenges as the antigen presentation by DCs, CTL escape mutations, B cell follicle sanctuary, host immune environment (inflammation, immune activation, tolerance), latent reservoir and the lack of surrogate markers of response. Finally, we will review the rationale for designing new therapeutic vaccine candidates to be used alone or in combination with other strategies to improve their effectiveness. Expert commentary: In the next future, the combination of DCs targeting candidates, inserts to redirect responses to unmutated parts of the virus, adjuvants to redirect responses to sanctuaries or improve the balance between activation/tolerance (IL-15, anti-PD1 antibodies) and latency reversing agents could be necessary to finally achieve the remission of HIV-1 infection.

Immune Interventions to Eliminate the HIV Reservoir

Inducing HIV remission is a monumental challenge. A potential strategy is the "kick and kill" approach where latently infected cells are first activated to express viral proteins and then eliminated through cytopathic effects of HIV or immune-mediated killing. However, pre-existing immune responses to HIV cannot eradicate HIV infection due to the presence of escape variants, inadequate magnitude, and breadth of responses as well as immune exhaustion. The two major approaches to boost immune-mediated elimination of infected cells include enhancing cytotoxic T lymphocyte mediated killing and harnessing antibodies to eliminate HIV. Specific strategies include increasing the magnitude and breadth of T cell responses through therapeutic vaccinations, reversing the effects of T cell exhaustion using immune checkpoint inhibition, employing bispecific T cell targeting immunomodulatory proteins or dual-affinity re-targeting molecules to direct cytotoxic T lymphocytes to virus-expressing cells and broadly neutralizing antibody infusions. Methods to steer immune responses to tissue sites where latently infected cells are located need to be further explored. Ultimately, strategies to induce HIV remission must be tolerable, safe, and scalable in order to make a global impact.

Dendritic Cell-Based Immunotherapies to Fight HIV: How Far from a Success Story? A Systematic Review and Meta-Analysis

The scientific community still faces the challenge of developing strategies to cure HIV-1. One of these pursued strategies is the development of immunotherapeutic vaccines based on dendritic cells (DCs), pulsed with the virus, that aim to boost HIV-1 specific immune response. We aimed to review DCs-based therapeutic vaccines reports and critically assess evidence to gain insights for the improvement of these strategies. We performed a systematic review, followed by meta-analysis and meta-regression, of clinical trial reports. Twelve studies were selected for meta-analysis. The experimental vaccines had low efficiency, with an overall success rate around 38% (95% confidence interval = 26.7%–51.3%). Protocols differed according to antigen choice, DC culture method, and doses, although multivariate analysis did not show an influence of any of them on overall success rate. The DC-based vaccines elicited at least some immunogenicity, that was sometimes associated with plasmatic viral load transient control. The protocols included both naïve and antiretroviral therapy (ART)-experienced individuals, and used different criteria for assessing vaccine efficacy. Although the vaccines did not work as expected, they are proof of concept that immune responses can be boosted against HIV-1. Protocol standardization and use of auxiliary approaches, such as latent HIV-1 reservoir activation and patient genomics are paramount for fine-tuning future HIV-1 cure strategies.

Ongoing Clinical Trials of Human Immunodeficiency Virus Latency-Reversing and Immunomodulatory Agents

In chronic human immunodeficiency virus (HIV)-1 infection, long-lived latently infected cells are the major barrier to virus eradication and functional cure. Several therapeutic strategies to perturb, eliminate, and/or control this reservoir are now being pursued in the clinic. These strategies include latency reversal agents (LRAs) designed to reactivate HIV-1 ribonucleic acid transcription and virus production and a variety of immune-modifying drugs designed to reverse latency, block homeostatic proliferation, and replenish the viral reservoir, eliminate virus-producing cells, and/or control HIV replication after cessation of antiretroviral therapy. This review provides a summary of ongoing clinical trials of HIV LRAs and immunomodulatory molecules, and it highlights challenges in the comparison and interpretation of the expected trial results.

The notorious R.N.A. in the spotlight - drug or target for the treatment of disease

mRNA is an attractive drug target for therapeutic interventions. In this review we highlight the current state, clinical trials, and developments in antisense therapy, including the classical approaches like RNaseH-dependent oligomers, splice-switching oligomers, aptamers, and therapeutic RNA interference. Furthermore, we provide an overview on emerging concepts for using RNA in therapeutic settings including protein replacement by in-vitro-transcribed mRNAs, mRNA as vaccines and anti-allergic drugs. Finally, we give a brief outlook on early-stage RNA repair approaches that apply endogenous or engineered proteins in combination with short RNAs or chemically stabilized oligomers for the re-programming of point mutations, RNA modifications, and frame shift mutations directly on the endogenous mRNA.