GITR activation ex vivo impairs CD8 T cell function in people with HIV on antiretroviral therapy.

Glucocorticoid-induced tumor necrosis factor related protein (GITR) is a co-stimulatory immune checkpoint molecule constitutively expressed on regulatory T cells (Tregs) and on activated T conventional cells (Tconv). In blood collected from PWH on suppressive ART, GITR expression was reduced in multiple activated CD4 and CD8 T cell subsets but was increased in Tregs. HIV specific CD8 T cells expressed higher levels of GITR and programmed cell death protein 1 (PD-1) compared to total CD8 T cells. Following stimulation with HIV peptides and GITR-ligand (L), we demonstrated a significant decrease in killing by HIV specific CD8 T cells and an increased exhausted profile. T cell receptor co-stimulation with GITR-L abrogated Treg suppression and induced expansion of CD4 Tconv. We conclude that GITR activation is an additional factor contributing to an impaired HIV immune response in PWH on ART and that GITR agonist antibodies should not be pursued for HIV cure strategies.

Immunomodulation with IL-7 and IL-15 in HIV-1 infection.

Immunomodulating agents are substances that modify the host immune responses in diseases such as infections, autoimmune conditions and cancers. Immunomodulators can be divided into two main groups: 1) immunostimulators that activate the immune system such as cytokines, toll-like receptor agonists and immune checkpoint blockers; and 2) immunosuppressors that dampen an overactive immune system such as corticosteroids and cytokine-blocking antibodies. In this review, we have focussed on the two primarily T and natural killer (NK) cell homeostatic cytokines: interleukin-7 (IL-7) and -15 (IL-15). These cytokines are immunostimulators which act on immune cells independently of the presence or absence of antigen. In vivo studies have shown that IL-7 administration enhances proliferation of circulating T cells whereas IL-15 agonists enhance the proliferation and function of NK and CD8+ T cells. Both IL-7 and IL-15 therapies have been tested as single interventions in HIV-1 cure-related clinical trials. In this review, we explore whether IL-7 and IL-15 could be part of the therapeutic approaches towards HIV-1 remission.

Effect of high dose vitamin D3 on the HIV-1 reservoir: A pilot randomised controlled trial.

Introduction: Antiretroviral therapy for people living with HIV-1 must be taken lifelong due to the persistence of latent virus in long-lived and proliferating CD4+ T cells. Vitamin D3 is a steroidal gene transcription regulator which exerts diverse effects on immune and epithelial cells including reductions in CD4+ T cell proliferation and improvement in gut barrier integrity. We hypothesised that a high dose of vitamin D3 would reduce the size of the HIV-1 reservoir by reducing CD4+ T cell proliferation. Methods: We performed a randomised placebo-controlled trial evaluating the effect of 24 weeks of vitamin D3 (10,000 international units per day) on the HIV-1 reservoir and immunologic parameters in 30 adults on antiretroviral therapy; participants were followed for 12 weeks post-treatment. The primary endpoint was the effect on total HIV-1 DNA at week 24. Parameters were assessed using mixed-effects models. Results: We found no effect of vitamin D3 on the change in total HIV-1 DNA from week 0 to week 24 relative to placebo. There were also no changes in integrated HIV-1 DNA, 2-long-terminal repeat (2-LTR) circles or cell-associated HIV-1 RNA. Vitamin D3 induced a significant increase in the proportion of central memory CD4+ and CD8+ T cells, a reduction in the proportion of senescent CD8+ T cells and a reduction in the natural killer cell frequency at all time points including week 36, 12 weeks after the study drug cessation. At week 36, there was a significant reduction in total HIV-1 DNA relative to placebo and persistently elevated 25-hydroxyvitamin D levels. No significant safety issues were identified. Conclusions: Vitamin D3 administration had a significant impact on the T cell differentiation but overall effects on the HIV-1 reservoir were limited and a reduction in HIV-1 DNA was only seen following cessation of the study drug. Additional studies are required to determine whether the dose and duration of vitamin D3 can be optimised to promote a continued depletion of the HIV-1 reservoir over time. Trial registration: ClinicalTrials.gov NCT03426592.

Impact of a TLR9 agonist and broadly neutralizing antibodies on HIV-1 persistence: the randomized phase 2a TITAN trial.

Inducing antiretroviral therapy (ART)-free virological control is a critical step toward a human immunodeficiency virus type 1 (HIV-1) cure. In this phase 2a, placebo-controlled, double-blinded trial, 43 people (85% males) with HIV-1 on ART were randomized to (1) placebo/placebo, (2) lefitolimod (TLR9 agonist)/placebo, (3) placebo/broadly neutralizing anti-HIV-1 antibodies (bNAbs) or (4) lefitolimod/bNAb. ART interruption (ATI) started at week 3. Lefitolimod was administered once weekly for the first 8 weeks, and bNAbs were administered twice, 1 d before and 3 weeks after ATI. The primary endpoint was time to loss of virologic control after ATI. The median delay in time to loss of virologic control compared to the placebo/placebo group was 0.5 weeks (P = 0.49), 12.5 weeks (P = 0.003) and 9.5 weeks (P = 0.004) in the lefitolimod/placebo, placebo/bNAb and lefitolimod/bNAb groups, respectively. Among secondary endpoints, viral doubling time was slower for bNAb groups compared to non-bNAb groups, and the interventions were overall safe. We observed no added benefit of lefitolimod. Despite subtherapeutic plasma bNAb levels, 36% (4/11) in the placebo/bNAb group compared to 0% (0/10) in the placebo/placebo group maintained virologic control after the 25-week ATI. Although immunotherapy with lefitolimod did not lead to ART-free HIV-1 control, bNAbs may be important components in future HIV-1 curative strategies. ClinicalTrials.gov identifier: NCT03837756 .

Soluble immune checkpoints as correlates for HIV persistence and T cell function in people with HIV on antiretroviral therapy.

Introduction: In people with HIV (PWH) both off and on antiretroviral therapy (ART), the expression of immune checkpoint (IC) proteins is elevated on the surface of total and HIV-specific T-cells, indicating T-cell exhaustion. Soluble IC proteins and their ligands can also be detected in plasma, but have not been systematically examined in PWH. Since T-cell exhaustion is associated with HIV persistence on ART, we aimed to determine if soluble IC proteins and their ligands also correlated with the size of the HIV reservoir and HIV-specific T-cell function. Methods: We used multiplex bead-based immunoassay to quantify soluble programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3), T cell immunoglobulin domain and mucin domain 3 (TIM-3), PD-1 Ligand 1 (PD-L1) and PD-1 Ligand 2 (PD-L2) in plasma from PWH off ART (n=20), on suppressive ART (n=75) and uninfected controls (n=20). We also quantified expression of membrane-bound IC and frequencies of functional T-cells to Gag and Nef peptide stimulation on CD4+ and CD8+ T-cells using flow cytometry. The HIV reservoir was quantified in circulating CD4+ T-cells using qPCR for total and integrated HIV DNA, cell-associated unspliced HIV RNA and 2LTR circles. Results: Soluble (s) PD-L2 level was higher in PWH off and on ART compared to uninfected controls. Higher levels of sPD-L2 correlated with lower levels of HIV total DNA and higher frequencies of gag-specific CD8+ T-cells expressing CD107a, IFNγ or TNFα. In contrast, the concentration of sLAG-3 was similar in uninfected individuals and PWH on ART, but was significantly elevated in PWH off ART. Higher levels of sLAG-3 correlated with higher levels of HIV total and integrated DNA, and lower frequency of gag-specific CD4+ T cells expressing CD107a. Similar to sLAG-3, levels of sPD-1 were elevated in PWH off ART and normalized in PWH on ART. sPD-1 was positively correlated with the frequency of gag-specific CD4+ T cells expressing TNF-a and the expression of membrane-bound PD-1 on total CD8+ T-cells in PWH on ART. Discussion: Plasma soluble IC proteins and their ligands correlate with markers of the HIV reservoir and HIV-specific T-cell function and should be investigated further in in large population-based studies of the HIV reservoir or cure interventions in PWH on ART.

Unequal distribution of genetically-intact HIV-1 proviruses in cells expressing the immune checkpoint markers PD-1 and/or CTLA-4.

Introduction: HIV-1 persists in resting CD4+ T-cells despite antiretroviral therapy (ART). Determining the cell surface markers that enrich for genetically-intact HIV-1 genomes is vital in developing targeted curative strategies. Previous studies have found that HIV-1 proviral DNA is enriched in CD4+ T-cells expressing the immune checkpoint markers programmed cell death protein-1 (PD-1) or cytotoxic T-lymphocyte associated protein-4 (CTLA-4). There has also been some success in blocking these markers in an effort to reverse HIV-1 latency. However, it remains unclear whether cells expressing PD-1 and/or CTLA-4 are enriched for genetically-intact, and potentially replication-competent, HIV-1 genomes. Methods: We obtained peripheral blood from 16 HIV-1-infected participants, and paired lymph node from four of these participants, during effective ART. Memory CD4+ T-cells from either site were sorted into four populations: PD-1-CTLA-4- (double negative, DN), PD-1+CTLA-4- (PD-1+), PD-1-CTLA-4+ (CTLA-4+) and PD-1+CTLA-4+ (double positive, DP). We performed an exploratory study using the full-length individual proviral sequencing (FLIPS) assay to identify genetically-intact and defective genomes from each subset, as well as HIV-1 genomes with specific intact open reading frames (ORFs). Results and Discussion: In peripheral blood, we observed that proviruses found within PD-1+ cells are more likely to have intact ORFs for genes such as tat, rev and nef compared to DN, CTLA-4+ and DP cells, all of which may contribute to HIV-1 persistence. Conversely, we observed that CTLA-4 expression is a marker for cells harbouring HIV-1 provirus that is more likely to be defective, containing low levels of these intact ORFs. In the lymph node, we found evidence that CTLA-4+ cells contain lower levels of HIV-1 provirus compared to the other cell subsets. Importantly, however, we observed significant participant variation in the enrichment of HIV-1 proviruses with intact genomes or specific intact ORFs across these memory CD4+ T-cell subsets, and therefore consideration of additional cellular markers will likely be needed to consistently identify cells harbouring latent, and potentially replication-competent, HIV-1.

Experience with sotrovimab treatment of SARS-CoV-2-infected patients in Denmark.

AIMS: To evaluate the experience with use of sotrovimab following severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in high-risk groups. METHODS: In a nationwide, population-based cohort study, we identified all individuals treated with sotrovimab (N = 2933) and stratified them by 4 high-risk groups: (A) malignant haematological disease, (B) solid organ transplantation, (C) anti-CD20 therapy ≤1 year and (D) other risks. Cox regression analysis was used to calculate hazard ratios for hospitalization, death and associated prognostic factors. RESULTS: Of 2933 sotrovimab-treated individuals, 83% belonged to high-risk groups (37.6% haematological malignancy, 27.4% solid organ transplantation and 17.5% treatment with anti-CD20 ≤1 year). Only 17.8% had other risks (11.8% were pregnant, 10.7% primary immunodeficiency, 21.2% other malignancy, 4.3% received anti-CD20 >1 year and 52.0% other/unknown causes). Within 90 days of infusion, 30.2% were hospitalized and 5.3% died. The main prognostic factors were the predefined high-risk groups, mainly malignant haematological disease and age ≥65 years. Number of COVID-19 vaccines (≥3) was associated with a decreased risk of hospitalization. The Delta but not the Omicron BA.2 variant was associated with a higher risk of death compared to the BA.1 variant. CONCLUSION: More than 90% of the patients treated with sotrovimab belonged to the very high-risk groups as described in the Danish guidelines. Sotrovimab-treated individuals remained at a high risk of hospitalization and death which was strongly associated with the underlying immunocompromised state and age. Having received >3 COVID-19 vaccines was association with decreased risk of death and hospitalization.

Memory CD4+ T cells that co-express PD1 and CTLA4 have reduced response to activating stimuli facilitating HIV latency.

Programmed cell death 1 (PD1) and cytotoxic T lymphocyte-associated protein 4 (CTLA4) suppress CD4+ T cell activation and may promote latent HIV infection. By performing leukapheresis (n = 21) and lymph node biopsies (n = 8) in people with HIV on antiretroviral therapy (ART) and sorting memory CD4+ T cells into subsets based on PD1/CTLA4 expression, we investigate the role of PD1 and CTLA 4 in HIV persistence. We show that double-positive (PD1+CTLA4+) cells in blood contain more HIV DNA compared with double-negative (PD1-CTLA4-) cells but still have a lower proportion of cells producing multiply spliced HIV RNA after stimulation as well as reduced upregulation of T cell activation and proliferation markers. Transcriptomics analyses identify differential expression of key genes regulating T cell activation and proliferation with MAF, KLRB1, and TIGIT being upregulated in double-positive compared with double-negative cells, whereas FOS is downregulated. We conclude that, in addition to being enriched for HIV DNA, double-positive cells are characterized by negative signaling and a reduced capacity to respond to stimulation, favoring HIV latency.

Factors associated with weak positive SARS-CoV-2 diagnosis by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR).

During the COVID-19 pandemic, the reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) assay has been the primary method of diagnosis of SARS-CoV-2 infection. However, RT-qPCR assay interpretation can be ambiguous with no universal absolute cut-off value to determine sample positivity, which particularly complicates the analysis of samples with high Ct values, or weak positives. Therefore, we sought to analyse factors associated with weak positive SARS-CoV-2 diagnosis. We analysed sample data associated with all positive SARS-CoV-2 RT-qPCR diagnostic tests performed by the Victorian Infectious Diseases Reference Laboratory (VIDRL) in Melbourne, Australia, during the Victorian first wave (22 January 2020-30 May 2020). A subset of samples was screened for the presence of host DNA and RNA using qPCR assays for CCR5 and 18S, respectively. Assays targeting the viral RNA-dependent RNA polymerase (RdRp) had higher Ct values than assays targeting the viral N and E genes. Weak positives were not associated with the age or sex of individuals' samples nor with reduced levels of host DNA and RNA. We observed a relationship between Ct value and time post-SARS-CoV-2 diagnosis. High Ct value or weak positive SARS-CoV-2 was not associated with any particular bias including poor biological sampling.

Antiretroviral Initiation at ≥800 CD4+ Cells/mm3 Associated With Lower Human Immunodeficiency Virus Reservoir Size.

BACKGROUND: Identifying factors that determine the frequency of latently infected CD4+ T cells on antiretroviral therapy (ART) may inform strategies for human immunodeficiency virus (HIV) cure. We investigated the role of CD4+ count at ART initiation for HIV persistence on ART. METHODS: Among participants of the Strategic Timing of Antiretroviral Treatment Study, we enrolled people with HIV (PWH) who initiated ART with CD4+ T-cell counts of 500-599, 600-799, or ≥ 800 cells/mm3. After 36-44 months on ART, the levels of total HIV-DNA, cell-associated unspliced HIV-RNA (CA-US HIV-RNA), and two-long terminal repeat HIV-DNA in CD4+ T cells were quantified and plasma HIV-RNA was measured by single-copy assay. We measured T-cell expression of Human Leucocyte Antigen-DR Isotype (HLA-DR), programmed death-1, and phosphorylated signal transducer and activator of transcription-5 (pSTAT5). Virological and immunological measures were compared across CD4+ strata. RESULTS: We enrolled 146 PWH, 36 in the 500-599, 60 in the 600-799, and 50 in the ≥ 800 CD4 strata. After 36-44 months of ART, total HIV-DNA, plasma HIV-RNA, and HLA-DR expression were significantly lower in PWH with CD4+ T-cell count ≥ 800 cells/mm3 at ART initiation compared with 600-799 or 500-599 cells/mm3. The median level of HIV-DNA after 36-44 months of ART was lower by 75% in participants initiating ART with ≥ 800 vs 500-599 cells/mm3 (median [interquartile range]: 16.3 [7.0-117.6] vs 68.4 [13.7-213.1] copies/million cells, respectively). Higher pSTAT5 expression significantly correlated with lower levels of HIV-DNA and CA-US HIV-RNA. Virological measures were significantly lower in females. CONCLUSIONS: Initiating ART with a CD4+ count ≥ 800 cells/mm3 compared with 600-799 or 500-599 cells/mm3 was associated with achieving a substantially smaller HIV reservoir on ART.

Immune checkpoint blockade in HIV.

Antiretroviral therapy (ART) has dramatically improved life expectancy for people with HIV (PWH) and helps to restore immune function but is not curative and must be taken lifelong. Achieving long term control of HIV in the absence of ART will likely require potent T cell function, but chronic HIV infection is associated with immune exhaustion that persists even on ART. This is driven by elevated expression of immune checkpoints that provide negative signalling to T cells. In individuals with cancer, immune checkpoint blockade augments tumour-directed T-cell responses resulting in significant clinical cures. There is therefore high interest if ICB can contribute to HIV cure or remission by reversing HIV-latency and/or drive recovery of HIV-specific T-cells. We here review recent evidence on the role of immune checkpoints in persistent HIV infection and discuss the potential for employing immune checkpoint blockade as a therapeutic approach to target HIV persistence on ART.

Balancing Statistical Power and Risk in HIV Cure Clinical Trial Design.

BACKGROUND: Analytical treatment interruptions (ATI) are pauses of antiretroviral therapy (ART) in the context of human immunodeficiency virus (HIV) cure trials. They are the gold standard in determining if interventions being tested can achieve sustained virological control in the absence of ART. However, withholding ART comes with risks and discomforts to trial participant. We used mathematical models to explore how ATI study design can be improved to maximize statistical power, while minimizing risks to participants. METHODS: Using previously observed dynamics of time to viral rebound (TVR) post-ATI, we modelled estimates for optimal sample size, frequency, and ATI duration required to detect a significant difference in the TVR between control and intervention groups. Groups were compared using a log-rank test, and analytical and stochastic techniques. RESULTS: In placebo-controlled TVR studies, 120 participants are required in each arm to detect 30% difference in frequency of viral reactivation at 80% power. There was little statistical advantage to measuring viral load more frequently than weekly, or interrupting ART beyond 5 weeks in a TVR study. CONCLUSIONS: Current TVR HIV cure studies are underpowered to detect statistically significant changes in frequency of viral reactivation. Alternate study designs can improve the statistical power of ATI trials.

Pembrolizumab induces HIV latency reversal in people living with HIV and cancer on antiretroviral therapy.

In people living with HIV (PLWH) on antiretroviral therapy (ART), virus persists in a latent form where there is minimal transcription or protein expression. Latently infected cells are a major barrier to curing HIV. Increasing HIV transcription and viral production in latently infected cells could facilitate immune recognition and reduce the pool of infected cells that persist on ART. Given that programmed cell death protein 1 (PD-1) expressing CD4+ T cells are preferentially infected with HIV in PLWH on ART, we aimed to determine whether administration of antibodies targeting PD-1 would reverse HIV latency in vivo. We therefore evaluated the impact of intravenous administration of pembrolizumab every 3 weeks on HIV latency in 32 PLWH and cancer on ART. After the first infusion of anti-PD-1, we observed a median 1.32-fold increase in unspliced HIV RNA and 1.61-fold increase in unspliced RNA:DNA ratio in sorted blood CD4+ T cells compared to baseline. We also observed a 1.65-fold increase in plasma HIV RNA. The frequency of CD4+ T cells with inducible virus evaluated using the tat/rev limiting dilution assay was higher after 6 cycles compared to baseline. Phylogenetic analyses of HIV env sequences in a participant who developed low concentrations of HIV viremia after 6 cycles of pembrolizumab did not demonstrate clonal expansion of HIV-infected cells. These data are consistent with anti-PD-1 being able to reverse HIV latency in vivo and support the rationale for combining anti-PD-1 with other interventions to reduce the HIV reservoir.

Neurotoxicity with high-dose disulfiram and vorinostat used for HIV latency reversal.

OBJECTIVE: The aim of this study was to examine whether administering both vorinostat and disulfiram to people with HIV (PWH) on antiretroviral therapy (ART) is well tolerated and can enhance HIV latency reversal. DESIGN: Vorinostat and disulfiram can increase HIV transcription in PWH on ART. Together, these agents may lead to significant HIV latency reversal. METHODS: Virologically suppressed PWH on ART received disulfiram 2000 mg daily for 28 days and vorinostat 400 mg daily on days 8-10 and 22-24. The primary endpoint was plasma HIV RNA on day 11 relative to baseline using a single copy assay. Assessments included cell-associated unspliced RNA as a marker of latency reversal, HIV DNA in CD4+ T-cells, plasma HIV RNA, and plasma concentrations of ART, vorinostat, and disulfiram. RESULTS: The first two participants (P1 and P2) experienced grade 3 neurotoxicity leading to trial suspension. After 24 days, P1 presented with confusion, lethargy, and ataxia having stopped disulfiram and ART. Symptoms resolved by day 29. After 11 days, P2 presented with paranoia, emotional lability, lethargy, ataxia, and study drugs were ceased. Symptoms resolved by day 23. CA-US RNA increased by 1.4-fold and 1.3-fold for P1 and P2 respectively. Plasma HIV RNA was detectable from day 8 to 37 (peak 81 copies ml-1) for P2 but was not increased in P1 Antiretroviral levels were therapeutic and neuronal injury markers were elevated in P1. CONCLUSION: The combination of prolonged high-dose disulfiram and vorinostat was not safe in PWH on ART and should not be pursued despite evidence of latency reversal.

Combination Immune Checkpoint Blockade Enhances IL-2 and CD107a Production from HIV-Specific T Cells Ex Vivo in People Living with HIV on Antiretroviral Therapy.

In people with HIV (PWH) on antiretroviral therapy (ART), immune dysfunction persists, including elevated expression of immune checkpoint (IC) proteins on total and HIV-specific T cells. Reversing immune exhaustion is one strategy to enhance the elimination of HIV-infected cells that persist in PWH on ART. We aimed to evaluate whether blocking CTL-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), T cell Ig domain and mucin domain 3 (TIM-3), T cell Ig and ITIM domain (TIGIT) and lymphocyte activation gene-3 (LAG-3) alone or in combination would enhance HIV-specific CD4+ and CD8+ T cell function ex vivo. Intracellular cytokine staining was performed using human PBMCs from PWH on ART (n = 11) and expression of CD107a, IFN-γ, TNF-α, and IL-2 was quantified with HIV peptides and Abs to IC. We found the following: 1) IC blockade enhanced the induction of CD107a and IL-2 but not IFN-γ and TNF-α in response to Gag and Nef peptides; 2) the induction of CD107a and IL-2 was greatest with multiple combinations of two Abs; and 3) Abs to LAG-3, CTLA-4, and TIGIT in combinations showed synergistic induction of IL-2 in HIV-specific CD8+ and CD107a and IL-2 production in HIV-specific CD4+ and CD8+ T cells. These results demonstrate that the combination of Abs to LAG-3, CTLA-4, or TIGIT can increase the frequency of cells expressing CD107a and IL-2 that associated with cytotoxicity and survival of HIV-specific CD4+ and CD8+ T cells in PWH on ART. These combinations should be further explored for an HIV cure.

Candidate host epigenetic marks predictive for HIV reservoir size, responsiveness to latency reversal, and viral rebound.

OBJECTIVE: This study aimed to identify candidate host epigenetic biomarkers predicting latency reversal agents (LRA) efficacy and HIV-1 rebound kinetics during analytical treatment interruption (ATI). DESIGN: Retrospective longitudinal epigenetic profiling study from 13 people with HIV (PWH) on virologically suppressive antiretroviral therapy (ART) that participated in a LRA (HDAC inhibitor) clinical trial (NCT01680094) and a subsequent optional ATI to monitor for viral recrudescence after ART cessation. METHODS: Genome-wide DNA methylation (DNAm) in purified CD4+ T cells was measured at single-nucleotide resolution using the Infinium MethylationEPIC array. HIV-1 DNA and RNA measures were previously assessed by PCR-based methods and the association of DNAm levels at regulatory sites of the human genome were examined with reservoir size, responsiveness to LRA, and time to viral rebound following ATI. RESULTS: A distinct set of 15 candidate DNAm sites in purified CD4+ T cells at baseline pre-LRA and pre-ATI significantly correlated with time to viral rebound. Eight of these DNAm sites occurred in genes linked to HIV-1 replication dynamics including (SEPSECS, cg19113954), (MALT1, cg15968021), (CPT1C, cg14318858), (CRTAM, cg10977115), (B4GALNT4, cg04663285), (IL10, cg16284789), (TFPI2, cg19645693), and (LIFR, cg26437306); with the remaining sites at intergenic regions containing regulatory elements. Moreover, baseline DNAm states related to total HIV-1 DNA levels and the fold change in unspliced cell-associated HIV RNA following LRA treatment. CONCLUSION: Preexisting host epigenetic states may determine HIV-1 rebound kinetics and reservoir maintenance. These findings suggest integrating a suite of DNA methylation markers to improve optimal participant selection and drug regimen in future HIV cure clinical trials.

Viral, inflammatory, and reservoir characteristics of posttreatment controllers.

PURPOSE OF REVIEW: To provide an overview of studies to date that have identified posttreatment controllers (PTCs) and to explore current evidence around clinical characteristics, immune effector function, and inflammatory and viral reservoir characteristics that may underlie the control mechanism. RECENT FINDINGS: PTCs are broadly defined as individuals capable of maintaining control of HIV replication after cessation of antiretroviral therapy (ART). While starting ART early after HIV infection is associated with PTC, genetic disposition or CD8+ T-cell function do not appear to explain this phenomenon, but these features have not been exhaustively analyzed in PTCs. A lower frequency of latently infected cells prior to stopping ART has been associated with achieving PTC, including a lower level of intact HIV DNA, but more studies are needed to map the genetic location, epigenetic characteristics, and tissue distribution of the intact HIV reservoir in PTCs. SUMMARY: Current studies are small and heterogeneous and there is a significant need to agree on a uniform definition of PTC. Many aspects of PTC are still unexplored including whether specific features of genetic disposition, immune effector functions, and/or viral reservoir characteristics play a role in PTC. A large multisite international cohort study could aide in providing the important insights needed to fully understand PTC.

The impact of immune checkpoint therapy on the latent reservoir in HIV-infected individuals with cancer on antiretroviral therapy.

OBJECTIVE: The aim of this study was to quantify HIV-specific immunological and virological changes in people with HIV (PWH) on antiretroviral therapy (ART) with malignancy who received immune checkpoint blockade (ICB). DESIGN: An observational cohort study. METHODS: Blood samples were collected before and after four cycles of ICB in HIV-positive adults on ART. Virological assessments performed on CD4+ T cells included cell-associated unspliced HIV RNA, cell-associated HIV DNA, Tat/rev-induced limiting dilution assay (TILDA) and plasma HIV RNA using a single copy assay (SCA). Flow cytometry was used to assess the frequency of precursor exhausted T cells (Tpex) and exhausted T cells (Tex), and Gag-specific CD4+ and CD8+ T cells positive for IFN-γ, TNF-α or CD107a by intracellular cytokine staining (ICS). RESULTS: Participant (P)1 received avelumab (anti-PD-L1) for Merkel cell carcinoma. P2 and P3 received ipilimumab (anti-CTLA-4) and nivolumab (anti-PD-1) for metastatic melanoma. An increase in CA-US RNA following each infusion was noted in all three participants. There were no consistent changes in HIV DNA or the proportion of cells with inducible MS HIV RNA. P2 demonstrated a striking increase in the frequency of gag-specific central and effector memory CD8+ T cells producing IFN-γ, TNF-α and CD107a following anti-PD1 and anti-CTLA-4. The frequency of CD8+ Tpex cells pre-ICB was also highest in this participant. CONCLUSION: In three PWH with cancer on ART, we found that ICB activated latent HIV and enhanced HIV-specific T cell function but with considerable variation.

Multiply spliced HIV RNA is a predictive measure of virus production ex vivo and in vivo following reversal of HIV latency.

BACKGROUND: One strategy being pursued to clear latently infected cells that persist in people living with HIV (PLWH) on antiretroviral therapy (ART) is to activate latent HIV infection with a latency reversing agent (LRA). Surrogate markers that accurately measure virus production following an LRA are needed. METHODS: We quantified cell-associated unspliced (US), multiply spliced (MS) and supernatant (SN) HIV RNA by qPCR from total and resting CD4+ T cells isolated from seven PLWH on ART before and after treatment ex vivo with different LRAs, including histone deacetylase inhibitors (HDACi). MS and plasma HIV RNA were also quantified from PLWH on ART (n-11) who received the HDACi panobinostat. FINDINGS: In total and resting CD4+ T cells from PLWH on ART, detection of US RNA was common while detection of MS RNA was infrequent. Primers used to detect MS RNA, in contrast to US RNA, bound sites of the viral genome that are commonly mutated or deleted in PLWH on ART. Following ex vivo stimulation with LRAs, we identified a strong correlation between the fold change increase in SN and MS RNA, but not the fold change increase in SN and US RNA. In PLWH on ART who received panobinostat, MS RNA was significantly higher in samples with detectable compared to non0detectable plasma HIV RNA. INTERPRETATION: Following administration of an LRA, quantification of MS RNA is more likely to reflect an increase in virion production and is therefore a better indicator of meaningful latency reversal. FUNDING: NHMRC, NIH DARE collaboratory.

Impact of Anti-PD-1 and Anti-CTLA-4 on the Human Immunodeficiency Virus (HIV) Reservoir in People Living With HIV With Cancer on Antiretroviral Therapy: The AIDS Malignancy Consortium 095 Study.

BACKGROUND: Antibodies to programmed cell death 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) may perturb human immunodeficiency virus (HIV) persistence during antiretroviral therapy (ART) by reversing HIV latency and/or boosting HIV-specific immunity, leading to clearance of infected cells. We tested this hypothesis in a clinical trial of anti-PD-1 alone or in combination with anti-CTLA-4 in people living with HIV (PLWH) and cancer. METHODS: This was a substudy of the AIDS Malignancy Consortium 095 Study. ART-suppressed PLWH with advanced malignancies were assigned to nivolumab (anti-PD-1) with or without ipilimumab (anti-CTLA-4). In samples obtained preinfusion and 1 and 7 days after the first and fourth doses of immune checkpoint blockade (ICB), we quantified cell-associated unspliced (CA-US) HIV RNA and HIV DNA. Plasma HIV RNA was quantified during the first treatment cycle. Quantitative viral outgrowth assay (QVOA) to estimate the frequency of replication-competent HIV was performed before and after ICB for participants with samples available. RESULTS: Of 40 participants, 33 received nivolumab and 7 nivolumab plus ipilimumab. Whereas CA-US HIV RNA did not change with nivolumab monotherapy, we detected a median 1.44-fold increase (interquartile range, 1.16-1.89) after the first dose of nivolumab and ipilimumab combination therapy (P = .031). There was no decrease in the frequency of cells containing replication-competent HIV, but in the 2 individuals on combination ICB for whom we had longitudinal QVOA, we detected decreases of 97% and 64% compared to baseline. CONCLUSIONS: Anti-PD-1 alone showed no effect on HIV latency or the latent HIV reservoir, but the combination of anti-PD-1 and anti-CTL-4 induced a modest increase in CA-US HIV RNA and may potentially eliminate cells containing replication-competent HIV. CLINICAL TRIALS REGISTRATION: NCT02408861.