Poster Presentation 9th Australasian Virology Society Meeting 2017

New HIV latency reversing agents that target novel gene expression pathways. (#151)

Jonathan Jacobson 1 , Brad Sleebs 2 , Kate Jarman 2 , William Nguyen 2 , Talia Mota 1 , Leigh Harty 1 , Georges Khoury 1 , Nicole Tay 1 , James McMahon 3 , Paul Cameron 1 , Sharon Lewin 1 3 , Damian Purcell 1
  1. Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
  2. Walter and Eliza Hall Institute, Parkville, VIC, Australia
  3. Infectious Disease Department, Alfred Hospital, Prahran, VIC, Australia

New HIV latency reversing agents (LRAs) with high potency and specificity are needed to achieve a sustained HIV remission without ongoing antiretroviral therapy (ART). We developed a dual reporter screening cell line to identify novel LRAs that specifically reactivate HIV-1 gene expression in conjunction with HIV RNA-processing pathways that support Tat-expression needed for full HIV-1 expression.

High-Throughput Chemical Screening (HTCS) of ~114,000 small drug-like compounds, using our dual luciferase reporter cell line model of HIV-1 latency, revealed a novel series of compounds including a family of Amidothiazols. These compounds were assessed in CD4+ T-cells isolated by leukapheresis from HIV+ individuals on ART to test in primary cells as single agents and in synergy with other LRAs using qPCR to test for HIV RNA in cells and in supernatant.

HTCS revealed a mechanistically and chemically novel class of Amidothiazols, that reactivate HIV-1 gene expression in a highly specific manner as single agents. These compounds act synergistically with bromodomain inhibitor JQ1(+) using Bliss Independence analysis (BI). The Amidothiazol LRA activity was confirmed in the J-Lat model of HIV latency. Successive rounds of medicinal chemistry increased the Amidothiazol potency of Gen1 (EC50=16.2μM) to Gen4 (EC50<100nM), a trend conserved across various cell line models of HIV latency. Two specificities emerged, one Tat-dependent and another Tat-independent for HIV LTR-activation. CD4+ T-cells collected by leukapharesis from HIV-infected individuals on ART confirmed that that the lead Amidothiazols activated production of HIV RNA in supernatant, at ~25% of the level induced by the PMA positive control. Furthermore, Amidothiazols synergised strongly with JQ1(+) to reactivate HIV-1 RNA production in patient derived cells (BI score = 0.196). We identified a family of Amidothiazols capable of specifically and potently reactivating HIV-1 by a novel mechanism of action that synergizes with BRD4 inhibition. Amidothiazols may have a place for sustained HIV-remission.