Effect of maraviroc intensification on HIV-1-specific T cell immunity in recently HIV-1-infected individuals

HIV-1-specific T-cell responses and exhaustion profiles in people with HIV after switching to dual therapy vs. maintaining triple therapy based on integrase inhibitors

BACKGROUND

Dual therapy (DT) has shown comparable results to triple therapy (TT) in efficacy and other immunological aspects. However, there are still some concerns about DT, including several immunological features. Therefore, we evaluated whether HIV-1-specific memory T-cell responses and exhaustion phenotypes are adversely influenced after simplification to DT.

METHODS

HIV-1-specific CD4+ and CD8+ T-cell responses were assessed by intracellular cytokine and degranulation marker staining, and polyfunctionality indexes after stimulation with a Gag peptide pool. Exhaustion phenotypes were evaluated by PD-1, TIM-3, and LAG-3 expression in CD4+ and CD8+ T cells.

RESULTS

Forty participants in the TRIDUAL trial (ClinicalTrials.gov: NCT03447873) who were randomized to continue integrase inhibitor-based TT (n = 20) or to switch to DT (dolutegravir or darunavir/cobicistat plus lamivudine) (n = 20). After 96 weeks, the magnitude of CD4+ and CD8+ T-cell responses was similar in both treatment arms (p = 0.221 and p = 0.602, respectively). The CD4+ polyfunctionality index decreased in the TT arm (p = 0.013) and remained stable in the DT arm, while the polyfunctionality of CD8+ T cells was unchanged in both arms. There was a significant decrease in the expression of PD-1, TIM-3, and the co-expression of PD-1+TIM-3+LAG-3+, and PD-1 +TIM-3 + in both CD4+ and CD8+ T cells. However, the decrease in the expression of exhaustion markers did not improve HIV-1-specific T-cell responses.

CONCLUSIONS

Our results suggest that simplification to DT does not negatively influence the HIV-1-specific T-cell response or the exhaustion phenotype after 96 weeks of follow-up.

Breadth and Durability of SARS-CoV-2-Specific T Cell Responses following Long-Term Recovery from COVID-19

T cell immunity is crucial for long-term immunological memory, but the profile of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific memory T cells in individuals who recovered from COVID-19 (COVID-19-convalescent individuals) is not sufficiently assessed. In this study, the breadth and magnitude of SARS-CoV-2-specific T cell responses were determined in COVID-19-convalescent individuals in Japan. Memory T cells against SARS-CoV-2 were detected in all convalescent individuals, and those with more severe disease exhibited a broader T cell response relative to cases with mild symptoms. Comprehensive screening of T cell responses at the peptide level was conducted for spike (S) and nucleocapsid (N) proteins, and regions frequently targeted by T cells were identified. Multiple regions in S and N proteins were targeted by memory T cells, with median numbers of target regions of 13 and 4, respectively. A maximum of 47 regions were recognized by memory T cells for an individual. These data indicate that SARS-CoV-2-convalescent individuals maintain a substantial breadth of memory T cells for at least several months following infection. Broader SARS-CoV-2-specific CD4+ T cell responses, relative to CD8+ T cell responses, were observed for the S but not the N protein, suggesting that antigen presentation is different between viral proteins. The binding affinity of predicted CD8+ T cell epitopes to HLA class I molecules in these regions was preserved for the Delta variant and at 94 to 96% for SARS-CoV-2 Omicron subvariants, suggesting that the amino acid changes in these variants do not have a major impact on antigen presentation to SARS-CoV-2-specific CD8+ T cells. IMPORTANCE RNA viruses, including SARS-CoV-2, evade host immune responses through mutations. As broader T cell responses against multiple viral proteins could minimize the impact of each single amino acid mutation, the breadth of memory T cells would be one essential parameter for effective protection. In this study, breadth of memory T cells to S and N proteins was assessed in COVID-19-convalescent individuals. While broad T cell responses were induced against both proteins, the ratio of N to S proteins for breadth of T cell responses was significantly higher in milder cases. The breadth of CD4+ and CD8+ T cell responses was also significantly different between S and N proteins, suggesting different contributions of N and S protein-specific T cells for COVID-19 control. Most CD8+ T cell epitopes in the immunodominant regions maintained their HLA binding to SARS-CoV-2 Omicron subvariants. Our study provides insights into understanding the protective efficacy of SARS-CoV-2-specific memory T cells against reinfection.

Safety, immunogenicity and effect on viral rebound of HTI vaccines in early treated HIV-1 infection: a randomized, placebo-controlled phase 1 trial

HIVACAT T-cell immunogen (HTI) is a novel human immunodeficiency virus (HIV) vaccine immunogen designed to elicit cellular immune responses to HIV targets associated with viral control in humans. The AELIX-002 trial was a randomized, placebo-controlled trial to evaluate as a primary objective the safety of a combination of DNA.HTI (D), MVA.HTI (M) and ChAdOx1.HTI (C) vaccines in 45 early-antiretroviral (ART)-treated individuals (44 men, 1 woman; NCT03204617). Secondary objectives included T-cell immunogenicity, the effect on viral rebound and the safety of an antiretroviral treatment interruption (ATI). Adverse events were mostly mild and transient. No related serious adverse events were observed. We show here that HTI vaccines were able to induce strong, polyfunctional and broad CD4 and CD8 T-cell responses. All participants experienced detectable viral rebound during ATI, and resumed ART when plasma HIV-1 viral load reached either >100,000 copies ml^-1, >10,000 copies ml^-1 for eight consecutive weeks, or after 24 weeks of ATI. In post-hoc analyses, HTI vaccines were associated with a prolonged time off ART in vaccinees without beneficial HLA (human leukocyte antigen) class I alleles. Plasma viral load at the end of ATI and time off ART positively correlated with vaccine-induced HTI-specific T-cell responses at ART cessation. Despite limited efficacy of the vaccines in preventing viral rebound, their ability to elicit robust T-cell responses towards HTI may be beneficial in combination cure strategies, which are currently being tested in clinical trials.

Sustainable antiviral efficacy of rejuvenated HIV-specific cytotoxic T lymphocytes generated from induced pluripotent stem cells

Persistence of HIV latently infected cells is a barrier to HIV cure. The "kick and kill" strategy for cure includes clearance of the viral reservoir by HIV-specific cytotoxic T lymphocytes (CTLs). However, exhaustion and senescence of T cells accelerates during HIV infection, and does not fully recover, despite complete viral suppression under antiretroviral therapy. We previously established an induced pluripotent stem cell (iPSC) from a parental HIV-specific CTL clone and generated an iPSC-derived rejuvenated HIV-specific CTL clone (iPSC-CTL), which exhibited an early memory phenotype, high proliferation capacity and effector functions in vitro . Here, we assessed the antiviral efficacy of the HIV-specific iPSC-CTL by single- and multiple-round viral suppression assays (VSAs). The HIV-specific iPSC-CTL suppressed viral replication in an HLA-dependent manner with equivalent efficacy to the parental CTL clone in single-round VSA. In multiple-round VSA, however, the ability of the iPSC-CTL to suppress viral replication was longer than that of the parental CTL clone. These results indicate that HIV-specific iPSC-CTL can sustainably exert suppressive pressure on viral replication, suggesting a novel approach to facilitate clearance of the HIV reservoir via adoptive transfer of rejuvenated CTLs.

Importance

Elimination of latently HIV-infected cells is required for HIV cure. In the “kick and kill” strategy proposed for HIV cure, the host immune system, including HIV-specific cytotoxic T lymphocytes (CTLs), play a central role in eliminating HIV antigen-expressing cells following reactivation by latency-reversing agents (LRAs). However, CTL dysfunction due to exhaustion and senescence in chronic HIV infection can be an obstacle to this strategy. Adoptive transfer with effective HIV-specific CTLs may be a solution of this problem. We previously generated an induced pluripotent stem cell (iPSC)-derived rejuvenated HIV-specific CTL clone (iPSC-CTL) with high functional and proliferative capacity. The present study demonstrates that iPSC-CTL can survive and suppress HIV replication in vitro longer than the parental CTL clone, indicating the potential of iPSC-CTL to sustainably exert suppressive pressure on viral replication. Adoptive transfer with rejuvenated HIV-specific CTLs in combination with LRAs may be a new intervention strategy for HIV cure/remission.

CCL5/CCR5 axis in human diseases and related treatments

To defense harmful stimuli or maintain the immune homeostasis, the body produces and recruits a superfamily of cytokines such as interleukins, interferons, chemokines etc. Among them, chemokines act as crucial regulators in defense systems. CCL5/CCR5 combination is known for facilitating inflammatory responses, as well as inducing the adhesion and migration of different T cell subsets in immune responses. In addition, recent studies have shown that the interaction between CCL5 and CCR5 is involved in various pathological processes including inflammation, chronic diseases, cancers as well as the infection of COVID-19. This review focuses on how CCL5/CCR5 axis participates in the pathological processes of different diseases and their relevant signaling pathways for the regulation of the axis. Moreover, we highlighted the gene therapy and chemotherapy studies for treating CCR5-related diseases, including the ongoing clinical trials. The barriers and perspectives for future application and translational research were also summarized.

HIVconsv Vaccines and Romidepsin in Early-Treated HIV-1-Infected Individuals: Safety, Immunogenicity and Effect on the Viral Reservoir (Study BCN02)

Kick&kill strategies combining drugs aiming to reactivate the viral reservoir with therapeutic vaccines to induce effective cytotoxic immune responses hold potential to achieve a functional cure for HIV-1 infection. Here, we report on an open-label, single-arm, phase I clinical trial, enrolling 15 early-treated HIV-1-infected individuals, testing the combination of the histone deacetylase inhibitor romidepsin as a latency-reversing agent and the MVA.HIVconsv vaccine. Romidepsin treatment resulted in increased histone acetylation, cell-associated HIV-1 RNA, and T-cell activation, which were associated with a marginally significant reduction of the viral reservoir. Vaccinations boosted robust and broad HIVconsv-specific T cells, which were strongly refocused toward conserved regions of the HIV-1 proteome. During a monitored ART interruption phase using plasma viral load over 2,000 copies/ml as a criterium for ART resumption, 23% of individuals showed sustained suppression of viremia up to 32 weeks without evidence for reseeding the viral reservoir. Results from this pilot study show that the combined kick&kill intervention was safe and suggest a role for this strategy in achieving an immune-driven durable viremic control.

Marginal Effects of Systemic CCR5 Blockade with Maraviroc on Oral Simian Immunodeficiency Virus Transmission to Infant Macaques

Current approaches do not eliminate all human immunodeficiency virus type 1 (HIV-1) maternal-to-infant transmissions (MTIT); new prevention paradigms might help avert new infections. We administered maraviroc (MVC) to rhesus macaques (RMs) to block CCR5-mediated entry, followed by repeated oral exposure of a CCR5-dependent clone of simian immunodeficiency virus (SIV) mac251 (SIVmac766). MVC significantly blocked the CCR5 coreceptor in peripheral blood mononuclear cells and tissue cells. All control animals and 60% of MVC-treated infant RMs became infected by the 6th challenge, with no significant difference between the number of exposures (P = 0.15). At the time of viral exposures, MVC plasma and tissue (including tonsil) concentrations were within the range seen in humans receiving MVC as a therapeutic. Both treated and control RMs were infected with only a single transmitted/founder variant, consistent with the dose of virus typical of HIV-1 infection. The uninfected RMs expressed the lowest levels of CCR5 on the CD4+ T cells. Ramp-up viremia was significantly delayed (P = 0.05) in the MVC-treated RMs, yet peak and postpeak viral loads were similar in treated and control RMs. In conclusion, in spite of apparent effective CCR5 blockade in infant RMs, MVC had a marginal impact on acquisition and only a minimal impact on the postinfection delay of viremia following oral SIV infection. Newly developed, more effective CCR5 blockers may have a more dramatic impact on oral SIV transmission than MVC.IMPORTANCE We have previously suggested that the very low levels of simian immunodeficiency virus (SIV) maternal-to-infant transmissions (MTIT) in African nonhuman primates that are natural hosts of SIVs are due to a low availability of target cells (CCR5+ CD4+ T cells) in the oral mucosa of the infants, rather than maternal and milk factors. To confirm this new MTIT paradigm, we performed a proof-of-concept study in which we therapeutically blocked CCR5 with maraviroc (MVC) and orally exposed MVC-treated and naive infant rhesus macaques to SIV. MVC had only a marginal effect on oral SIV transmission. However, the observation that the infant RMs that remained uninfected at the completion of the study, after 6 repeated viral challenges, had the lowest CCR5 expression on the CD4+ T cells prior to the MVC treatment appears to confirm our hypothesis, also suggesting that the partial effect of MVC is due to a limited efficacy of the drug. New, more effective CCR5 inhibitors may have a better effect in preventing SIV and HIV transmission.

Characterization of In Vitro Expanded Virus-Specific T cells for Adoptive Immunotherapy against Virus Infection

Adoptive transfer of virus-specific T cells has emerged as a promising therapeutic approach for treatment of virus infections in immunocompromised hosts. Characterization of virus-specific T cells provides essential information about the curative mechanism of the treatment. In this study, we developed a T cell epitope mapping system for 718 overlapping peptides spanning 6 proteins of 3 viruses (pp65 and IE1 from cytomegalovirus; LMP1, EBNA1, and BZLF1 from Epstein-Barr virus; Penton from adenovirus). Peripheral blood mononuclear cells (PBMCs) from 33 healthy Japanese donors were stimulated with these peptides and virus-specific CD4⁺ and CD8⁺ T cells were expanded in vitro in the presence of interleukin (IL) 4 and IL7. A median of 13 (minimum-maximum, 2-46) peptides was recognized in the cohort. Both fresh and cryopreserved PBMCs were used for in vitro expansion. The expansion and breadth of T cell responses were not significantly different between the 2 PBMC sets. We assessed viral regions frequently recognized by T cells in a Japanese cohort that could become pivotal T cell targets for immunotherapy in Japan. We tested epitope prediction for CD8⁺ T cell responses against a common target region using a freely available online tool. Some epitopes were considered to be predictive.

Temporary CXCR3 and CCR5 antagonism following vaccination enhances memory CD8 T cell immune responses

Although current vaccination strategies have been successful at preventing a variety of human diseases, attempts at vaccinating against some pathogens such as AIDS and tuberculosis (TB) have been more problematic, largely in that abnormally high numbers of antigen specific CD8+ T cells are required for protection. This study assessed the effect of temporarily dampening the chemokine receptor CXCR3 and CCR5 after vaccination on host immune responses by the administration of TAK-779, a small molecule CXCR3 and CCR5 antagonists commonly used to inhibit HIV infection. Our results showed that the use of TAK-779 enhanced memory CD8+ T cell immune responses both qualitatively and quantitatively. Treatment with TAK-779 following vaccination of an influenza virus antigen resulted in enhanced memory generation with more CD8+CD127+ memory precursor and fewer terminally differentiated effector CD8+CD69+ T cells. These memory T cells were able to become IFN-γ-secreting effector cells when re-encountered the same antigen, which can further enhance the efficacy of vaccination. The mice vaccinated in the presence of TAK-779 were better protected upon influenza virus challenge than the control. These results showed that vaccination while temporarily inhibiting chemokine receptor CXCR3 and CCR5 by TAK-779 could be a promising strategy to generate large number of protective memory CD8+ T cells.

Full Length Single Chain Fc Protein (FLSC IgG1) as a Potent Antiviral Therapy Candidate: Implications for In Vivo Studies

We have previously shown that FLSC, a chimeric protein containing HIV-1BAL gp120 and the D1 and D2 domains of human CD4, blocks the binding and entry of HIV-1 into target cells by occluding CCR5, the major HIV-1 coreceptor. In an effort to improve the antiviral potential of FLSC, we fused it with the hinge-CH2-CH3 region of human IgG1. The IgG moiety should increase both the affinity and stability in vivo of FLSC, due to the resultant bivalency and an extended serum half-life, thereby increasing its antiviral potency. We previously showed that (FLSC) IgG1 indeed had greater antiviral activity against T cell infections. Here we extend these results to macrophages, for which (FLSC) IgG1 has a more potent antiviral activity than FLSC alone, due in part to its higher binding affinity for CCR5. We also test both compounds in a relevant humanized mouse model and show that, as anticipated, the IgG1 moiety confers a greatly extended half-life. These data, taken together with previous results, suggest potential clinical utility for (FLSC) IgG1 and support further developmental work toward eventual clinical trials.

Maraviroc: a review of its use in HIV infection and beyond

The human immunodeficiency virus-1 (HIV-1) enters target cells by binding its envelope glycoprotein gp120 to the CD4 receptor and/or coreceptors such as C-C chemokine receptor type 5 (CCR5; R5) and C-X-C chemokine receptor type 4 (CXCR4; X4), and R5-tropic viruses predominate during the early stages of infection. CCR5 antagonists bind to CCR5 to prevent viral entry. Maraviroc (MVC) is the only CCR5 antagonist currently approved by the United States Food and Drug Administration, the European Commission, Health Canada, and several other countries for the treatment of patients infected with R5-tropic HIV-1. MVC has been shown to be effective at inhibiting HIV-1 entry into cells and is well tolerated. With expanding MVC use by HIV-1-infected humans, different clinical outcomes post-approval have been observed with MVC monotherapy or combination therapy with other antiretroviral drugs, with MVC use in humans infected with dual-R5- and X4-tropic HIV-1, infected with different HIV-1 genotype or infected with HIV-2. This review discuss the role of CCR5 in HIV-1 infection, the development of the CCR5 antagonist MVC, its pharmacokinetics, pharmacodynamics, drug-drug interactions, and the implications of these interactions on treatment outcomes, including viral mutations and drug resistance, and the mechanisms associated with the development of resistance to MVC. This review also discusses available studies investigating the use of MVC in the treatment of other diseases such as cancer, graft-versus-host disease, and inflammatory diseases.

Preclinical discovery and development of maraviroc for the treatment of HIV

INTRODUCTION

Maraviroc is a first-in-class antiretroviral (ARV) drug acting on a host cell target (CCR5), which blocks the entry of the HIV virus into the cell. Maraviroc is currently indicated for combination ARV treatment in adults infected only with CCR5-tropic HIV-1.

AREAS COVERED

This drug discovery case history focuses on the key studies that led to the discovery and approval of maraviroc, as well as on post-launch clinical reports. The article is based on the data reported in published preclinical and clinical studies, conference posters and on drug package data.

EXPERT OPINION

The profound understanding of HIV's entry mechanisms has provided a strong biological rationale for targeting the chemokine receptor CCR5. The CCR5-antagonist mariviroc, with its unique mode of action and excellent safety profile, is an important therapeutic option for HIV patients. In general, the authors believe that targeting host factors is a useful approach for combating new and re-emerging transmissible diseases, as well as pathogens that easily become resistant to common antiviral drugs. Maraviroc, offering a potent and safe cellular receptor-mediated pharmacological response to HIV, has paved the way for the development of a new generation of host-targeting antivirals.

Effect of therapeutic intensification followed by HIV DNA prime and rAd5 boost vaccination on HIV-specific immunity and HIV reservoir (EraMune 02): a multicentre randomised clinical trial

BACKGROUND

Achievement of a cure for HIV infection might need reactivation of latent virus and improvement of HIV-specific immunity. As an initial step, in this trial we assessed the effect of antiretroviral therapy intensification and immune modulation with a DNA prime and recombinant adenovirus 5 (rAd5) boost vaccine.

METHODS

In this multicentre, randomised, open-label, non-comparative, phase 2 clinical trial, we enrolled eligible adults 18-70 years of age with chronic HIV-1 infection on suppressive antiretroviral therapy with current CD4 count of at least 350 cells per μL and HIV DNA between 10 and 1000 copies per 10(6) peripheral blood mononuclear cells. After an 8 week lead-in of antiretroviral intensification therapy (standard dose raltegravir and dose-adjusted maraviroc based on baseline antiretroviral therapy), patients were randomly assigned (1:1) to receive antiretroviral therapy intensification alone or intensification plus injections of HIV DNA prime vaccine (4 mg VRC-HIVDNA016-00-VP) at weeks 8, 12, and 16, followed by HIV rAd5 boost vaccine (10(10) particle units of VRC-HIVADV014-00-VP) at week 32. Randomisation was computer generated in permuted blocks of six and was stratified by study site. The primary endpoint was a 0·5 log10 or greater decrease in HIV DNA in peripheral blood mononuclear cells at week 56. This study is registered with ClinicalTrials.gov, number NCT00976404.

FINDINGS

Between Nov 29, 2010, and Oct 28, 2011, we enrolled 28 eligible patients from three academic HIV clinics in the USA. After the 8 week lead-in of antiretroviral intensification therapy, 14 patients were randomly assigned to continue antiretroviral therapy intensification alone and 14 to intensification plus vaccine. Enrolled participants had median CD4 count of 636 cells per μL, median HIV DNA 170 copies per 10(6) peripheral blood mononuclear cells, and duration of antiretroviral therapy of 13 years. The median amount of HIV DNA did not change significantly between baseline and week 56 in the antiretroviral therapy intensification plus vaccine group. One participant in the antiretroviral therapy intensification alone group reached the primary endpoint, with 0·55 log10 decrease in HIV DNA in peripheral blood mononuclear cells. Both treatments were well tolerated. No severe or systemic reactions to vaccination occurred, and five serious adverse events were recorded during the study, most of which resolved spontaneously or were judged unrelated to study treatments.

INTERPRETATION

Antiretroviral therapy intensification followed by DNA prime and rAd5 boost vaccine did not significantly increase HIV expression or reduce the latent HIV reservoir. A multifaceted approach that includes stronger activators of HIV expression and novel immune modulators will probably be needed to reduce the latent HIV reservoir and allow for long-term control in patients off antiretroviral therapy.

FUNDING

Objectif Recherche Vaccin SIDA (ORVACS).