CROI 2015 Program and Abstracts

Abstract Listing

Oral Abstracts

Conclusions: Clones of HIV-infected PBMC that persist during suppressive ART are capable of producing virions. LLV appear to originate from virion expression from proliferating infected cell clones or from low–level replication. 108 Treatment With a TLR7 Agonist Induces Transient Viremia in SIV-Infected ART-Suppressed Monkeys James B. Whitney 1 ; So-Yon Lim 1 ; Christa E. Osuna 1 ; Srisowmya Sanisetty 1 ;Tiffany L. Barnes 2 ; PeterT. Hraber 3 ;Tomas Cihlar 2 ; Romas Geleziunas 2 ; Joseph Hesselgesser 2 1 Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, US; 2 Gilead Sciences, Inc., Foster City, CA, US; 3 Los Alamos National Laboratories, Los Alamos, NM, US Background: Latent reservoirs of replication competent HIV-1 persist in patients on antiretroviral therapy (ART) and represent the major obstacle to HIV eradication efforts. Considerable effort has been directed to identify pharmaceutical agents capable of safely reactivating latent HIV-1 in ART-suppressed patients. Methods: A study was conducted in SIV-infected rhesus macaques (RM) on ART to determine if administration of an oral toll-like receptor 7 (TLR7) agonist would induce transient plasma viremia and reduce viral reservoirs. Ten RM were infected with SIVmac251 by rectal challenge. Plasma SIV RNA levels were measured by RT-PCR (limit of detection 50 copies/mL). The RM received ART at ~9 weeks post-infection (PI) and became virologically suppressed by 24 weeks PI; virologic suppression was maintained through week 45. At 45 weeks PI, 4 RM were administered 7 doses of the TLR7 agonist at twice monthly intervals, while on ART. The first 3 doses were 0.1, 0.2 and 0.3 mg/kg and the last 4 doses remained constant at 0.3 mg/kg. Total viral DNA was quantified in peripheral blood mononuclear cells (PBMC), colon and lymph node biopsies taken pre- and post-completion of TLR7 treatment. Two weeks after TLR7 dosing, ART was discontinued. Results: The first 3 doses of TLR7 agonist administered to the SIV-infected ART-suppressed RM had limited effect on plasma viremia. However, doses 4 through 7 led to transient and consistent increases in plasma virus (500 - 1000 SIV RNA copies/mL) in all treated RMs with a return to < 50 copies/mL within 4-7 days of TLR7 dosing. After completion of the TLR7 regimen, SIV DNA levels were reduced by 56-75% in PBMC, colon and lymphoid tissues. Viral DNA levels remained unchanged in the placebo control RM. To determine if these transient plasma virus blips and decreases in viral DNA content also reduced the size of the viral reservoir, ART was discontinued. While the plasma virus rebound kinetics in animals dosed with the TLR7 agonist were comparable to the placebo group after discontinuation of ART, the TLR7 treated animals showed a ~0.5 log 10 reduction in plasma virus setpoint as compared to the placebo group. Conclusions: Multiple oral administrations of a TLR7 agonist in SIV-infected ART-suppressed RM was safe, induced transient plasma viremia, reduced viral DNA content in PBMCs, colon and lymphoid tissues and established lower viral setpoint after ART cessation. These novel findings support clinical investigation of a TLR7 agonist in HIV-1 infected patients on ART. 109 Panobinostat Broadly Activates Latent HIV-1 Proviruses in Patients Kirston M. Barton 1 ;Thomas A. Rasmussen 2 ; MartinTolstrup 2 ;Wei Shao 4 ; Bonnie Hiener 1 ; Ajantha Solomon 3 ; Lars Østergaard 2 ; Sharon R. Lewin 3 ; Ole Søgaard 2 ; Sarah E. Palmer 1 1 Westmead Millennium Institute and University of Sydney, Westmead, Australia; 2 Aarhus University Hospital, Aarhus, Denmark; 3 Doherty Institute for Infection and Immunity, Melbourne, Australia; 4 National Cancer Institute, Rockville, MD, US Background: To target the persistence of quiescent HIV-1 during ART, HDAC inhibitors have been used to induce viral transcription, which could potentially facilitate viral clearance. It is important that all replication competent proviruses are activated to fully purge infection. Therefore, we performed an in-depth analysis of the panobinostat clinical trial to determine whether the observed increases in unspliced cell-associated RNA (CA RNA) were due to transcription from a subset or a broad range of proviruses. Methods: Panobinostat was administered to 15 patients on suppressive ART three times a week every other week for eight weeks (i.e., four cycles of drug). Cell-associated DNA (CA DNA) and RNA were extracted from PBMCs collected before, twice while receiving and four weeks after the final dose of panobinostat treatment. Additionally, plasma samples were collected prior to initiation of ART (nine patients) and during a post-panobinostat analytical treatment interruption (ATI, nine patients) to assess circulating HIV-1. Single- genome sequencing of the env region was used to characterise the virus from the cell-associated DNA and RNA and plasma RNA. Results: The sequences obtained from the preART plasma reflected the infection status of the patient (acute vs. chronic). Phylogenetic analysis revealed that the panobinostat- induced viral RNA intermingled extensively with the CA DNA sequences from the equivalent time points, indicating that panobinostat activates transcription from a broad range of proviruses. The rebound virus from the ATI plasma was composed of expansions of homogenous sequences, and the sequences from this virus were genetically similar to the panobinostat-induced CA RNA sequences. Furthermore, CA DNA sequences that were identical to the rebound virus were detected. A significantly higher percentage of the sequences from the CA RNA were hypermutated compared to the CA DNA (p=0.04). Conclusions: Panobinostat non-selectively activates transcription from quiescent proviruses in patients on suppressive ART, supporting its ability to activate HIV-1 from latency. Furthermore, panobinostat activated virus that was genetically similar to that observed during ATI, indicating that it targets virus that drives rebound following treatment discontinuation. The high percentage of hypermutated HIV CA RNA that was detected stresses the need for assays that measure replication competent virus when assessing latency reversing agents. 110LB The Size of the Active HIV Reservoir Predicts Timing of Viral Rebound Behzad Etemad 1 ; Hayat Ahmed 1 ; Evgenia Aga 2 ; Ronald Bosch 2 ; JohnW. Mellors 3 ; Daniel Kuritzkes 1 ; Michael Para 4 ; RajeshT. Gandhi 5 ; Jonathan Li 1 1 Brigham and Women’s Hospital, Harvard Medical School, Cambridge, MA, US; 2 Harvard School of Public Health, Center for Biostatistics in AIDS Research, Boston, MA, US; 3 University of Pittsburgh, Pittsburgh, PA, US; 4 Ohio State University, Columbus, OH, US; 5 Massachusetts General Hospital, Harvard Medical School, Boston, MA, US Background: Strategies to achieve sustained ART-free HIV remission will require validation in analytic treatment interruption (ATI) trials. Identifying virologic biomarkers that can predict time to viral rebound could accelerate the development of such therapeutics. We examined the association of pre-ATI cell-associated RNA (CA-RNA), DNA (CA-DNA), and residual viremia (RV) with timing of viral rebound during ATI. Methods: We performed a retrospective combined analysis of participants from 5 ACTG studies who were virologically suppressed on ART and received no immunologic intervention prior to undergoing ATI. The timing of viral rebound was evaluated at either (1) confirmed viral load ≥ 200 HIV RNA copies/mL or (2) single viral load ≥ 1,000 HIV RNA copies/mL. Unspliced CA-RNA and CA-DNA were quantified using qPCR, and RV by the single-copy assay. Results: Participants who initiated ART during acute/early infection (n=20) had lower levels of pre-ATI CA-RNA than those treated during chronic infection (n=104) (median <1.58 vs. 1.83 log 10 HIV-1 RNA copies/10 6 PBMCs, P<0.01). No significant differences were seen in pre-ATI levels of CA-DNA or RV between those treated during acute/early vs. chronic infection. There were no significant differences by ART regimen (NNRTI vs. PI-based) in pre-ATI CA-RNA, CA-DNA, or RV. Higher pre-ATI CA-RNA levels were significantly associated with shorter time to viral rebound using a threshold of either 200 HIV-1 RNA copies/mL ( ≤ 4 wks [N=75] vs. 5-8 wks [N=35] vs. >8 wks [N=14]: 1.83 vs. 1.68 vs.<1.58 log 10 HIV-1 RNA copies/10 6 PBMCs, Kruskal-Wallis P<0.01] or 1,000 HIV-1 RNA copies/mL (1.83 vs. 1.69 vs. <1.58 log 10 HIV-1 RNA copies/10 6 PBMCs, P<0.01). The proportion of participants with detectable RV ≥ 1 copy/mL was significantly higher in those with shorter time to ≥ 200 HIV-1 RNA copies/mL ( ≤ 4 wks vs. 5-8 wks vs. ≥ 8 wks: 47% vs. 29% vs. 8%, Fisher’s P=0.02]. No significant association was seen between CA-DNA levels and timing of viral rebound. A modest correlation was detected between levels of pre-ATI CA-RNA and CA-DNA (Spearman r =0.16, P=0.08).

Oral Abstracts

139

CROI 2015