icon-    folder.gif   Conference Reports for NATAP  
  Conference on Retroviruses
and Opportunistic Infections (CROI)
February 13-16, 2017, Seattle WA
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  Reported by Jules Levin
CROI 2017 Feb 14-16 Seattle WA
Jessica Brehm1,2, Vincent Tai1, David Irlbeck1,2, Robert Ferris1,2, Nancie Archin2, Matt Kanke2, Jean-Pierre Routy3, Angela Kashuba2, David Margolis2, Jun Tang1,2 and David Favre1,2 1GlaxoSmithKline, 2University of North Carolina HIV Cure Center, 3McGill Univ Health Centre
Webcast - http://www.croiwebcasts.org/console/player/33580?mediaType=slideVideo&


Abstract Body:
Protein kinase C agonists (PKCa) are potent in vitro latency reversing agents (LRAs) that act synergistically with histone deacetylase inhibitors (HDACi) and bromodomain inhibitors (iBET), suggesting their potential use in HIV cure strategies. Here we confirm and extend prior testing of the PKCa Ingenol-B (IngB) in vitro. Because IngB is unstable at physiological pH conditions, a stabilized form of Ingenol (GSK445A) was developed and tested in vitro and in the non-human primate model.
The ability of IngB to reverse latency in vitro was tested in reporter cell lines and in total or resting CD4+ T cells from stably-treated HIV-infected donors. Reactivation was measured by cell-associated RNA (caRNA), tat/rev induced limiting dilution assay (TILDA) and quantitative viral outgrowth assays (QVOA). IngB, GSK445A and iBET151 as single agents, fixed-dose combination and dose-response curves were measured. Cellular responses were profiled in vitro for cytotoxicity, cell signaling and transcriptomics. The pharmacology and biomarkers of GSK445A were analyzed in blood and tissues of healthy and chronically SIV-infected rhesus macaques (RM).
The effective concentrations 50 (EC50) of GSK445A and IngB were 1 and 13 nM, respectively, in HIV-Jurkat cell lines compared with ~200 nM for IngB in primary CD4+ T cells of HIV donors (caRNA), with latency reversal confirmed by TILDA and QVOA. Cell signaling and transcriptional profiling demonstrated rapid and potent activation of NFkB, Akt and MAPK pathways in CD4+ T cells. Combination activity of IngB with iBET151 showed a 5 to 10-fold increase in potency and maximal response by caRNA and was confirmed by TILDA, suggesting synergy in the reactivation of a large pool of latently infected cells. In vivo, a brief infusion of GSK445A at 5 to 20ug/kg was well tolerated in RM (n=20). Pharmacokinetics of GSK445A displayed a biphasic decline with exposure above the EC50 for 3-6 hours. Rapid increase in plasma IL-6, T cell trafficking and up-regulation of CD69 (10-60% in T cells) revealed dose-dependent responses in blood and lymphoid tissues, which returned to baseline after 6 to 48 hours.
In vitro, GSK445A and IngB reversed HIV latency; activity was augmented by iBET151. GSK445A was developed as a stable Ingenol derivative that was well tolerated at an effective dose in RM making GSK445A a candidate for single and combination studies to test latency reversal and clearance in vivo.