Antiretroviral therapy alone versus antiretroviral therapy with a kick and kill approach, on measures of the HIV reservoir in participants with recent HIV infection (the RIVER trial): a phase 2, randomised trial.

BACKGROUND: Antiretroviral therapy (ART) cannot cure HIV infection because of a persistent reservoir of latently infected cells. Approaches that force HIV transcription from these cells, making them susceptible to killing-termed kick and kill regimens-have been explored as a strategy towards an HIV cure. RIVER is the first randomised trial to determine the effect of ART-only versus ART plus kick and kill on markers of the HIV reservoir. METHODS: This phase 2, open-label, multicentre, randomised, controlled trial was undertaken at six clinical sites in the UK. Patients aged 18-60 years who were confirmed as HIV-positive within a maximum of the past 6 months and started ART within 1 month from confirmed diagnosis were randomly assigned by a computer generated randomisation list to receive ART-only (control) or ART plus the histone deacetylase inhibitor vorinostat (the kick) and replication-deficient viral vector T-cell inducing vaccines encoding conserved HIV sequences ChAdV63. HIVconsv-prime and MVA.HIVconsv-boost (the kill; ART + V + V; intervention). The primary endpoint was total HIV DNA isolated from peripheral blood CD4+ T-cells at weeks 16 and 18 after randomisation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, NCT02336074. FINDINGS: Between June 14, 2015 and Jul 11, 2017, 60 men with HIV were randomly assigned to receive either an ART-only (n=30) or an ART + V + V (n=30) regimen; all 60 participants completed the study, with no loss-to-follow-up. Mean total HIV DNA at weeks 16 and 18 after randomisation was 3·02 log10 copies HIV DNA per 106 CD4+ T-cells in the ART-only group versus 3·06 log10 copies HIV DNA per 106 CD4+ T-cells in ART + V + V group, with no statistically significant difference between the two groups (mean difference of 0·04 log10 copies HIV DNA per 106 CD4+ T-cells [95% CI -0·03 to 0·11; p=0·26]). There were no intervention-related serious adverse events. INTERPRETATION: This kick and kill approach conferred no significant benefit compared with ART alone on measures of the HIV reservoir. Although this does not disprove the efficacy kick and kill strategy, for future trials enhancement of both kick and kill agents will be required. FUNDING: Medical Research Council (MR/L00528X/1).

Cellular Gene Modulation of HIV-Infected CD4 T Cells in Response to Serial Treatment with the Histone Deacetylase Inhibitor Vorinostat.

Histone deacetylase inhibitors (HDACi) are the most widely studied HIV latency-reversing agents (LRAs). The HDACi suberoylanilide hydroxamic acid (vorinostat [VOR]) has been employed in several clinical HIV latency reversal studies, as well as in vitro models of HIV latency, and has been shown to effectively induce HIV RNA and protein expression. Despite these findings, response to HDACi can vary, particularly with intermittent dosing, and information is lacking on the relationship between the host transcriptional response and HIV latency reversal. Here, we report on global gene expression responses to VOR and examine the longevity of the transcriptional response in various cellular models. We found that many genes are modulated at 6 h post-VOR treatment in HCT116, Jurkat, and primary resting CD4 T cells, yet return to baseline levels after an 18-h VOR-free period. With repeat exposure to VOR in resting CD4 T cells, we found similar and consistent transcriptional changes at 6 h following each serial treatment. In addition, serial exposure in HIV-infected suppressed donor CD4 T cells showed consistent transcriptional changes after each exposure to VOR. We identified five host genes that were strongly and consistently modulated following histone deacetylase (HDAC) inhibition; three (H1F0, IRGM, and WIPI49) were upregulated, and two (PHF15 and PRDM10) were downregulated. These genes demonstrated consistent modulation in peripheral blood mononuclear cell (PBMC) samples from HIV-positive (HIV+) participants who received either single or multiple doses of 400 mg of VOR. Interestingly, the host transcriptional response did not predict induction of cell-associated HIV RNA, suggesting that other cellular factors play key roles in HIV latency reversal in vivo despite robust HDACi pharmacological activity.IMPORTANCE Histone deacetylase inhibitors are widely studied HIV latency-reversing agents (LRAs). VOR, an HDACi, induces histone acetylation and chromatin remodeling and modulates host and HIV gene expression. However, the relationship between these events is poorly defined, and clinical studies suggest diminished HIV reactivation in resting CD4 T cells with daily exposure to VOR. Our study provides evidence that VOR induces a consistent level of host cell gene transcription following intermittent exposure. In addition, in response to VOR exposure a gene signature that was conserved across single and serial exposures both in vitro and in vivo was identified, indicating that VOR can consistently and reproducibly modulate transcriptional host responses. However, as the HIV response to HDACi declines over time, other factors modulate viral reactivation in vivo despite robust HDAC activity. The identified host gene VOR biomarkers can be used for monitoring the pharmacodynamic activity of HDAC inhibitors.

Discovery of macrocyclic HDACs 1, 2, and 3 selective inhibitors for HIV latency reactivation.

A series of unique macrocyclic HDACs 1, 2, and 3 selective inhibitors were identified with good enzymatic activity and high selectivity over HDACs 6 and 8. These macrocyclic HDAC inhibitors used an ethyl ketone as the zinc-binding group. Compounds 25 and 26 stood out as leads due to their low double-digit nM EC50s in the 2C4 cell-based HIV latency reactivation assay. The PK profiles of these macrocyclic HDAC inhibitors still needed improvement.

Superinfection and cure of infected cells as mechanisms for hepatitis C virus adaptation and persistence.

RNA viruses exist as a genetically diverse quasispecies with extraordinary ability to adapt to abrupt changes in the host environment. However, the molecular mechanisms that contribute to their rapid adaptation and persistence in vivo are not well studied. Here, we probe hepatitis C virus (HCV) persistence by analyzing clinical samples taken from subjects who were treated with a second-generation HCV protease inhibitor. Frequent longitudinal viral load determinations and large-scale single-genome sequence analyses revealed rapid antiviral resistance development, and surprisingly, dynamic turnover of dominant drug-resistant mutant populations long after treatment cessation. We fitted mathematical models to both the viral load and the viral sequencing data, and the results provided strong support for the critical roles that superinfection and cure of infected cells play in facilitating the rapid turnover and persistence of viral populations. More broadly, our results highlight the importance of considering viral dynamics and competition at the intracellular level in understanding rapid viral adaptation. Thus, we propose a theoretical framework integrating viral and molecular mechanisms to explain rapid viral evolution, resistance, and persistence despite antiviral treatment and host immune responses.

Letermovir Resistance Analysis in a Clinical Trial of Cytomegalovirus Prophylaxis for Hematopoietic Stem Cell Transplant Recipients.

BACKGROUND: Letermovir (LET), a cytomegalovirus (CMV) deoxyribonucleic acid (DNA) terminase inhibitor, was recently approved for prophylaxis of CMV infection in adult CMV-seropositive recipients of allogeneic hematopoietic stem cell transplantation. Cytomegalovirus genotyping was performed to identify LET-resistance-associated variants (RAVs) among subjects in a Phase 3 trial. METHODS: The CMV UL56 and UL89 genes, encoding subunits of CMV DNA terminase, were sequenced from plasma collected from subjects with clinically significant CMV infection (CS-CMVi). Novel variants were evaluated by recombinant phenotyping to assess their potential to confer resistance to LET. RESULTS: Genotyping was successful for 50 of 79 LET subjects with CS-CMVi. Resistance-associated variants (encoding pUL56 V236M and C325W) were detected independently in subjects 1 and 3 who experienced CS-CMVi while receiving LET prophylaxis, and 2 other variants (encoding pUL56 E237G and R369T) were detected >3 weeks after subjects 2 and 3, respectively, had discontinued LET prophylaxis and received preemptive therapy with ganciclovir. CONCLUSIONS: The detected incidence of CMV resistance among subjects who received LET as prophylaxis in this Phase 3 trial was low. The LET RAVs that were detected mapped to the CMV UL56 gene at positions associated with reduced susceptibility to LET based on resistance selections in cell culture.

Differentiation into an Effector Memory Phenotype Potentiates HIV-1 Latency Reversal in CD4+ T Cells.

During antiretroviral therapy (ART), human immunodeficiency virus type 1 (HIV-1) persists as a latent reservoir in CD4+ T cell subsets in central memory (TCM), transitional memory (TTM), and effector memory (TEM) CD4+ T cells. We have identified differences in mechanisms underlying latency and responses to latency-reversing agents (LRAs) in ex vivo CD4+ memory T cells from virally suppressed HIV-infected individuals and in an in vitro primary cell model of HIV-1 latency. Our ex vivo and in vitro results demonstrate the association of transcriptional pathways of T cell differentiation, acquisition of effector function, and cell cycle entry in response to LRAs. Analyses of memory cell subsets showed that effector memory pathways and cell surface markers of activation and proliferation in the TEM subset are predictive of higher frequencies of cells carrying an inducible reservoir. Transcriptional profiling also demonstrated that the epigenetic machinery (known to control latency and reactivation) in the TEM subset is associated with frequencies of cells with HIV-integrated DNA and inducible HIV multispliced RNA. TCM cells were triggered to differentiate into TEM cells when they were exposed to LRAs, and this increase of TEM subset frequencies upon LRA stimulation was positively associated with higher numbers of p24+ cells. Together, these data highlight differences in underlying biological latency control in different memory CD4+ T cell subsets which harbor latent HIV in vivo and support a role for differentiation into a TEM phenotype in facilitating latency reversal.IMPORTANCE By performing phenotypic analysis of latency reversal in CD4+ T cells from virally suppressed individuals, we identify the TEM subset as the largest contributor to the inducible HIV reservoir. Differential responses of memory CD4+ T cell subsets to latency-reversing agents (LRAs) demonstrate that HIV gene expression is associated with heightened expression of transcriptional pathways associated with differentiation, acquisition of effector function, and cell cycle entry. In vitro modeling of the latent HIV reservoir in memory CD4+ T cell subsets identify LRAs that reverse latency with ranges of efficiency and specificity. We found that therapeutic induction of latency reversal is associated with upregulation of identical sets of TEM-associated genes and cell surface markers shown to be associated with latency reversal in our ex vivo and in vitro models. Together, these data support the idea that the effector memory phenotype supports HIV latency reversal in CD4+ T cells.

Development of a selective HDAC inhibitor aimed at reactivating the HIV latent reservoir.

The synthesis and SAR development of a trisubstituted imidazole HDAC inhibitor is described. The compounds were synthesized with high diastereocontrol by leveraging Ellman sulfinyl imine chemistry. Structural elucidation provided insight into binding mode and supported design rational. Pharmacokinetic properties of lead compounds were determined.

Discovery of ethyl ketone-based HDACs 1, 2, and 3 selective inhibitors for HIV latency reactivation.

A novel series of ethyl ketone based HDACs 1, 2, and 3 selective inhibitors have been identified with good enzymatic and cellular activity and high selectivity over HDACs 6 and 8. These inhibitors contain a spirobicyclic group in the amide region. Compound 13 stands out as a lead due to its good potency, high selectivity, and reasonable rat and dog PK. Compounds 33 and 34 show good potency and rat PK profiles as well.

Virologic resistance analysis from a phase 2 study of MK-5172 combined with pegylated interferon/ribavirin in treatment-naive patients with hepatitis C virus genotype 1 infection.

BACKGROUND: Virologic failure following treatment of hepatitis C virus (HCV) genotype 1 with direct-acting antiviral agents is often accompanied by the emergence of resistant variants. MK-5172 is an investigational once-daily protease inhibitor. We analyzed variants in treatment-naive noncirrhotic patients with virologic failure on MK-5172 (100-800 mg/day) plus pegylated interferon alfa/ribavirin (peg-IFN/RBV) during a phase 2 trial. METHODS: Population and selective clonal sequencing were performed at baseline and at virologic failure in the 4 MK-5172 dosing arms. MK-5172 activity was determined using a mutant replicon assay. RESULTS: Six of 266 (2.3%) MK-5172 recipients satisfied prespecified criteria for virologic failure, all with genotype 1a infection. Five patients with virologic failure were in the MK-5172 100-mg arm, including 4 patients with low plasma MK-5172 levels documented during triple therapy. Variants associated with >4-fold loss of potency were detected in 3 of the 4 patients with genotype 1a breakthrough while on MK-5172. The fifth patient had undetectable HCV-RNA levels at the end of triple therapy but subsequently broke through during the peg-IFN/RBV tail 16 weeks after completion of MK-5172. Three patients had D168 variants at virologic failure, including 2 with the D168A variant associated with a 95-fold loss of potency. The sole apparent relapse was actually a genotype 3a reinfection in the MK-5172 200-mg group. CONCLUSIONS: Virologic failure occurred uncommonly (6/266 [2.3%]) in MK-5172/peg-IFN/RBV recipients. The most prevalent treatment-emergent variants were detected at the D168 locus. D168A variants conferring approximately 2-log reduction in MK-5172 susceptibility emerged in 2 of the 4 evaluable patients with genotype 1a breakthrough. Clinical Trials Registration. NCT01353911.

Combination of vaniprevir with peginterferon and ribavirin significantly increases the rate of SVR in treatment-experienced patients with chronic HCV genotype 1 infection and cirrhosis.

BACKGROUND & AIMS: The combination of vaniprevir (a NS3/4A protease inhibitor) with peginterferon and ribavirin was shown to increase rates of sustained virologic response (SVR) significantly, compared with peginterferon and ribavirin alone, in treatment-experienced patients with chronic hepatitis C virus (HCV) genotype 1 infection without cirrhosis. We performed a blinded, randomized, controlled trial of the effects of vaniprevir with peginterferon and ribavirin in patients with cirrhosis who did not respond to prior therapy with peginterferon and ribavirin. METHODS: Treatment-experienced patients (88% white and 35% prior null responders) with HCV genotype 1 infection and compensated cirrhosis were assigned randomly to groups given vaniprevir (600 mg twice daily) with peginterferon and ribavirin for 24 weeks (n = 16), vaniprevir (600 mg twice daily) for 24 weeks with peginterferon and ribavirin for 48 weeks (n = 14), vaniprevir (300 mg twice daily) with peginterferon and ribavirin for 48 weeks (n = 15), vaniprevir (600 mg twice daily) with peginterferon and ribavirin for 48 weeks (n = 15), or placebo with peginterferon and ribavirin for 48 weeks (n = 14, control). Cirrhosis was documented by liver biopsy (84%) or noninvasive methods (16%). Before randomization, participants were stratified based on their historical response to peginterferon and ribavirin. RESULTS: In the primary analysis, SVR rates among patients in the respective vaniprevir groups were 9 of 15 (60.0%), 9 of 13 (69.2%), 8 of 15 (53.3%), and 10 of 13 (76.9%), compared with 2 of 14 (14.3%) in the control group (pairwise P values ≤ .016). Cirrhotic patients with null or partial responses to prior therapy achieved SVR less often than patients with prior breakthrough or relapse, although 42.1% of prior null responders in the vaniprevir groups achieved SVRs. Patients in the vaniprevir groups more frequently experienced mild-moderate nausea, vomiting, and diarrhea than controls; 5% developed grade 2 anemia compared with none in the control group (no patient developed grade 3 or 4 anemia). Among patients in the vaniprevir groups who experienced virologic failure, resistance-associated variants were detected predominantly at positions 155, 156, and 168 in the HCV protease gene. CONCLUSIONS: In a controlled phase 2B trial, vaniprevir with peginterferon and ribavirin significantly increased rates of SVR among treatment-experienced patients with chronic HCV genotype 1 infection, compared with re-treatment with peginterferon and ribavirin alone. Vaniprevir generally was well tolerated for up to 48 weeks in patients with compensated cirrhosis. ClinicalTrials.gov number, NCT00704405.

Antiviral activity of boceprevir monotherapy in treatment-naive subjects with chronic hepatitis C genotype 2/3.

BACKGROUND & AIMS: To examine the antiviral activity of boceprevir, a hepatitis C virus (HCV) protease inhibitor, in HCV genotype (G) 2/3-infected patients. METHODS: We assessed boceprevir and telaprevir activity against an HCV G2 and G3 isolates enzyme panel, in replicon, and in phenotypic cell-based assays. Additionally, a phase I study evaluated the antiviral activity of boceprevir monotherapy (200mg BID, 400mg BID, or 400mg TID) vs. placebo for 14 days in HCV G2/3 treatment-naive patients. RESULTS: Boceprevir and telaprevir similarly inhibited G1 and G2 NS3/4A enzymes and replication in G1 and G2 replicon and cell-based assays. However, telaprevir demonstrated lower potency than boceprevir against HCV G3a enzyme (Ki=75 nM vs. 17 nM), in the G3a replicon assay (EC50=953 nM vs. 159 nM), and against HCV G3a NS3 isolates (IC50=3312 nM vs. 803 nM) in the cell-based assay. In HCV G2/3-infected patients, boceprevir (400 mg TID) resulted in a maximum mean decrease in HCV RNA of -1.60 log vs. -0.21 log with placebo. CONCLUSIONS: In vitro, boceprevir is more active than telaprevir against the HCV G3 NS3/4A enzyme in cell-based and biochemical assays and against G3 isolates in replicon assays. In HCV G2/3-infected treatment-naive patients, decreases in HCV RNA levels with boceprevir (400 mg TID) were comparable to those observed with the same dose in HCV treatment-experienced G1-infected patients.

A phase 2B study of MK-7009 (vaniprevir) in patients with genotype 1 HCV infection who have failed previous pegylated interferon and ribavirin treatment.

BACKGROUND & AIMS: MK-7009 (vaniprevir) is a non-covalent competitive inhibitor of the hepatitis C virus (HCV) NS3/4A protease. This report presents the primary analysis results (safety and sustained viral response) of a phase 2b study of MK-7009 given in combination with peginterferon (PegIFN) alfa2a 180 µg weekly and ribavirin (RBV) 1000-1200 mg/day, for 24-48 weeks to non-cirrhotic patients who have failed previous PegIFN and RBV treatment. METHODS: We present results of a randomized, placebo-controlled, double-blind study of MK-7009 administered for 24-48 weeks in combination with PegIFN and RBV in 4 regimens to at least 40 patients per arm. Stratification by prior response to PegIFN and RBV was as follows: null response, partial response, breakthrough and relapse. HCV RNA was determined by Roche Cobas Taqman with a lower limit of detection (LLoD) of 10 IU/ml and a lower limit of quantification (LLoQ) of 25 IU/ml. RESULTS: SVR24 in patients on MK-7009+PegIFN and ribavirin (P/R) was statistically superior to placebo+P/R in all treatment groups (p<0.001). MK-7009 at 300 mg b.i.d. and 600 mg b.i.d. is generally well tolerated for use for up to 48 weeks of therapy. Patients in MK-7009 regimens had higher rates of gastrointestinal adverse events as compared to control (mostly mild to moderate). There were no significant differences in rates of anemia and rash between the MK-7009 regimens and control. CONCLUSIONS: In conclusion, patients treated with MK-7009 plus P/R experienced significant improvement in SVR compared to P/R control in a population of GT 1 experienced patients.

Boceprevir with peginterferon alfa-2a-ribavirin is effective for previously treated chronic hepatitis C genotype 1 infection.

BACKGROUND & AIMS: The addition of boceprevir to therapy with peginterferon alfa-2b and ribavirin results in significantly higher rates of sustained virologic response (SVR) in previously treated patients with chronic hepatitis C virus (HCV) genotype-1 infection, compared with peginterferon alfa-2b and ribavirin alone. We assessed SVR with boceprevir plus peginterferon alfa-2a-ribavirin (PEG2a/R) in patients with identical study entry criteria. METHODS: In a double-blind, placebo-controlled trial, 201 patients with HCV genotype-1 who had relapsed or not responded to previous therapy were assigned to groups (1:2) and given a 4-week lead-in phase of PEG2a/R, followed by placebo plus PEG2a/R for 44 weeks (PEG2a/R) or boceprevir plus PEG2a/R for 44 weeks (BOC/PEG2a/R). The primary end point was SVR 24 weeks after therapy ended. RESULTS: The addition of boceprevir after 4 weeks of lead-in therapy with PEG2a/R significantly increased the rate of SVR from 21% in the PEG2a/R group to 64% in the BOC/PEG2a/R group (P < .0001). Among patients with poor response to interferon therapy (<1-log(10) decline in HCV RNA at week 4), 39% in the BOC/PEG2a/R group had SVRs, compared with none of the patients in the PEG2a/R group. Among patients with good response to interferon (≥1-log(10) decline), 71% in the BOC/PEG2a/R group had SVRs, compared with 25% in the PEG2a/R group. A ≥1-log(10) decline in HCV RNA at treatment week 4 was the strongest independent predictor of SVR, exceeding that of IL-28B genotype. Among 8 patients who began the study with HCV amino acid variants associated with boceprevir resistance, 3 (38%) achieved SVRs. Fifty percent of patients in the BOC/PEG2a/R group developed anemia (hemoglobin <10.0 g/dL), compared with 27% in the PEG2a/R group; 43% vs 21%, respectively, developed neutropenia (neutrophil count <750/mm(3)). CONCLUSIONS: The addition of boceprevir after 4 weeks of lead-in therapy with PEG2a/R caused significantly higher rates of SVR in previously treated patients with chronic HCV genotype-1 infection, compared with patients given only PEG2a/R. ClinicalTrials.gov Identifier: NCT00845065.

Vaniprevir with pegylated interferon alpha-2a and ribavirin in treatment-naïve patients with chronic hepatitis C: a randomized phase II study.

UNLABELLED: Vaniprevir (MK-7009) is a macrocyclic hepatitis C virus (HCV) nonstructural protein 3/4A protease inhibitor. The aim of the present phase II study was to examine virologic response rates with vaniprevir in combination with pegylated interferon alpha-2a (Peg-IFN-α-2a) plus ribavirin (RBV). In this double-blind, placebo-controlled, dose-ranging study, treatment-naïve patients with HCV genotype 1 infection (n = 94) were randomized to receive open-label Peg-IFN-α-2a (180 µg/week) and RBV (1,000-1,200 mg/day) in combination with blinded placebo or vaniprevir (300 mg twice-daily [BID], 600 mg BID, 600 mg once-daily [QD], or 800 mg QD) for 28 days, then open-label Peg-IFN-α-2a and RBV for an additional 44 weeks. The primary efficacy endpoint was rapid viral response (RVR), defined as undetectable plasma HCV RNA at week 4. Across all doses, vaniprevir was associated with a rapid two-phase decline in viral load, with HCV RNA levels approximately 3 log(10) IU/mL lower in vaniprevir-treated patients, compared to placebo recipients. Rates of RVR were significantly higher in each of the vaniprevir dose groups, compared to the control regimen (68.8%-83.3% versus 5.6%; P < 0.001 for all comparisons). There were numerically higher, but not statistically significant, early and sustained virologic response rates with vaniprevir, as compared to placebo. Resistance profile was predictable, with variants at R155 and D168 detected in a small number of patients. No relationship between interleukin-28B genotype and treatment outcomes was demonstrated in this study. The incidence of adverse events was generally comparable between vaniprevir and placebo recipients; however, vomiting appeared to be more common at higher vaniprevir doses. CONCLUSION: Vaniprevir is a potent HCV protease inhibitor with a predictable resistance profile and favorable safety profile that is suitable for QD or BID administration.

Pharmacodynamic analysis of a serine protease inhibitor, MK-4519, against hepatitis C virus using a novel in vitro pharmacodynamic system.

The development of new antiviral compounds active against hepatitis C virus (HCV) has surged in recent years. In order for these new compounds to be efficacious in humans, optimal dosage regimens for each compound must be elucidated. We have developed a novel in vitro pharmacokinetic/pharmacodynamic system, the BelloCell system, to identify optimal dosage regimens for anti-HCV compounds. In these experiments, genotype 1b HCV replicon-bearing cells (2209-23 cells) were inoculated onto carrier flakes in BelloCell bottles and treated with MK-4519, a serine protease inhibitor. Our dose-ranging studies illustrated that MK-4519 inhibited replicon replication in a dose-dependent manner, yielding a 50% effective concentration (EC(50)) of 1.8 nM. Dose-fractionation studies showed that shorter dosing intervals resulted in greater replicon suppression, indicating that the time that the concentration is greater than the EC(50) is the pharmacodynamic parameter for MK-4519 linked with inhibition of replicon replication. Mutations associated with resistance to serine protease inhibitors were detected in replicons harvested from all treatment arms. These data suggest that MK-4519 is highly active against genotype 1b HCV, but monotherapy is not sufficient to prevent the amplification of resistant replicons. In summary, our findings show that the BelloCell system is a useful and clinically relevant tool for predicting optimal dosage regimens for anti-HCV compounds.

Interleukin-10 contributes to reservoir establishment and persistence in SIV-infected macaques treated with antiretroviral therapy.

Interleukin-10 (IL-10) is an immunosuppressive cytokine that signals through STAT3 to regulate T follicular helper (Tfh) cell differentiation and germinal center formation. In SIV-infected macaques, levels of IL-10 in plasma and lymph nodes (LNs) were induced by infection and not normalized with antiretroviral therapy (ART). During chronic infection, plasma IL-10 and transcriptomic signatures of IL-10 signaling were correlated with the cell-associated SIV-DNA content within LN CD4+ memory subsets, including Tfh cells, and predicted the frequency of CD4+ Tfh cells and their cell-associated SIV-DNA content during ART, respectively. In ART-treated rhesus macaques, cells harboring SIV-DNA by DNAscope were preferentially found in the LN B cell follicle in proximity to IL-10. Finally, we demonstrated that the in vivo neutralization of soluble IL-10 in ART-treated, SIV-infected macaques reduced B cell follicle maintenance and, by extension, LN memory CD4+ T cells, including Tfh cells and those expressing PD-1 and CTLA-4. Thus, these data support a role for IL-10 in maintaining a pool of target cells in lymphoid tissue that serve as a niche for viral persistence. Targeting IL-10 signaling to impair CD4+ T cell survival and improve antiviral immune responses may represent a novel approach to limit viral persistence in ART-suppressed people living with HIV.

Monosynaptic restriction of transsynaptic tracing from single, genetically targeted neurons.

There has never been a wholesale way of identifying neurons that are monosynaptically connected either to some other cell group or, especially, to a single cell. The best available tools, transsynaptic tracers, are unable to distinguish weak direct connections from strong indirect ones. Furthermore, no tracer has proven potent enough to label any connected neurons whatsoever when starting from a single cell. Here we present a transsynaptic tracer that crosses only one synaptic step, unambiguously identifying cells directly presynaptic to the starting population. Based on rabies virus, it is genetically targetable, allows high-level expression of any gene of interest in the synaptically coupled neurons, and robustly labels connections made to single cells. This technology should enable a far more detailed understanding of neural connectivity than has previously been possible.

Switch to a raltegravir-based regimen versus continuation of a lopinavir-ritonavir-based regimen in stable HIV-infected patients with suppressed viraemia (SWITCHMRK 1 and 2): two multicentre, double-blind, randomised controlled trials.

BACKGROUND: To reduce lipid abnormalities and other side-effects associated with antiretroviral regimens containing lopinavir-ritonavir, patients might want to switch one or more components of their regimen. We compared substitution of raltegravir for lopinavir-ritonavir with continuation of lopinavir-ritonavir in HIV-infected patients with stable viral suppression on lopinavir-ritonavir-based combination therapy. METHODS: The SWITCHMRK 1 and 2 studies were multicentre, double-blind, double-dummy, phase 3, randomised controlled trials. HIV-infected patients aged 18 years or older were eligible if they had documented viral RNA (vRNA) concentration below the limit of assay quantification for at least 3 months while on a lopinavir-ritonavir-based regimen. 707 eligible patients were randomly allocated by interactive voice response system in a 1:1 ratio to switch from lopinavir-ritonavir to raltegravir (400 mg twice daily; n=353) or to remain on lopinavir-ritonavir (two 200 mg/50 mg tablets twice daily; n=354), while continuing background therapy consisting of at least two nucleoside or nucleotide reverse transcriptase inhibitors. Primary endpoints were the mean percentage change in serum lipid concentrations from baseline to week 12; the proportion of patients with vRNA concentration less than 50 copies per mL at week 24 (with all treated patients who did not complete the study counted as failures) with a prespecified non-inferiority margin of -12% for each study; and the frequency of adverse events up to 24 weeks. Analyses were done according to protocol. These trials are registered with ClinicalTrials.gov, numbers NCT00443703 and NCT00443729. FINDINGS: 702 patients received at least one dose of study drug and were included in the efficacy and safety analyses for the combined trials (raltegravir, n=350; lopinavir-ritonavir, n=352). Percentage changes in lipid concentrations from baseline to week 12 were significantly greater (p<0.0001) in the raltegravir group than in the lopinavir-ritonavir group in each study, yielding combined results for total cholesterol -12.6%vs 1.0%, non-HDL cholesterol -15.0%vs 2.6%, and triglycerides -42.2%vs 6.2%. At week 24, 293 (84.4%, 95% CI 80.2-88.1) of 347 patients in the raltegravir group had vRNA concentration less than 50 copies per mL compared with 319 (90.6%, 87.1-93.5) of 352 patients in the lopinavir-ritonavir group (treatment difference -6.2%, -11.2 to -1.3). Clinical and laboratory adverse events occurred at similar frequencies in the treatment groups. There were no serious drug-related adverse events or deaths. The only drug-related clinical adverse event of moderate to severe intensity reported in 1% or more of either treatment group was diarrhoea, which occurred in ten patients in the lopinavir-ritonavir group (3%) and no patients in the raltegravir group. The studies were terminated at week 24 because of lower than expected virological efficacy in the raltegravir group compared with the lopinavir-ritonavir group. INTERPRETATION: Although switching to raltegravir was associated with greater reductions in serum lipid concentrations than was continuation of lopinavir-ritonavir, efficacy results did not establish non-inferiority of raltegravir to lopinavir-ritonavir. FUNDING: Merck.

In Vitro Pharmacokinetic/Pharmacodynamic Modeling of HIV Latency Reversal by Novel HDAC Inhibitors Using an Automated Platform.

Antiretroviral therapy is able to effectively control but not eradicate HIV infection, which can persist, leading to the need for lifelong therapy. The existence of latently HIV-infected cells is a major barrier to the eradication of chronic HIV infection. Histone deacetylase inhibitors (HDACis), small molecules licensed for oncology indications, have shown the ability to produce HIV transcripts in vitro and in vivo. The pharmacologic parameters that drive optimal HIV latency reversal in vivo are unknown and could be influenced by such factors as the HDACi binding kinetics, concentration of compound, and duration of exposure. This study evaluates how these parameters affect HIV latency reversal for a series of novel HDACis that differ in their enzymatic on and off rates. Varying cellular exposure, using automated washout methods of HDACi in a Jurkat cell model of HIV latency, led to the investigation of the relationship between pharmacokinetic (PK) properties, target engagement (TE), and pharmacodynamic (PD) responses. Using an automated robotic platform enabled miniaturization of a suspension cell-based washout assay that required multiple manipulations over the 48 h duration of the assay. Quantification of histone acetylation (TE) revealed that HDACis showed early peaks and differences in the durability of response between different investigated HDACis. By expanding the sample times, the shift between TE and PD, as measured by green fluorescent protein, could be fully characterized. The comprehensive data set generated by automating the assays described here was used to establish a PK/PD model for HDACi-induced HIV latency reversal.

Discovery of Ethyl Ketone-Based Highly Selective HDACs 1, 2, 3 Inhibitors for HIV Latency Reactivation with Minimum Cellular Potency Serum Shift and Reduced hERG Activity.

We describe the discovery of histone deacetylase (HDACs) 1, 2, and 3 inhibitors with ethyl ketone as the zinc-binding group. These HDACs 1, 2, and 3 inhibitors have good enzymatic and cellular activity. Their serum shift in cellular potency has been minimized, and selectivity against hERG has been improved. They are also highly selective over HDACs 6 and 8. These inhibitors contain a variety of substituted heterocycles on the imidazole or oxazole scaffold. Compounds 31 and 48 stand out due to their good potency, high selectivity over HDACs 6 and 8, reduced hERG activity, optimized serum shift in cellular potency, and good rat and dog PK profiles.