The leading approach to eradicate HIV consists of the induction of latency reversal and subsequent clearance of cells reactivating the virus. Here, we tested a novel latency reversing agent (LRA) strategy that selectively activates the non-canonical NF-κB pathway (ncNF-κB) using a mimetic of the second mitochondrial-derived activator of caspases (SMACm).
We evaluated the SMACm AZD5582 in 12 SIV-infected ART-suppressed rhesus macaques (RM) compared to 9 controls. After over a year of ART, RM received 3-10 weekly doses of AZD5582 intravenously at 100 μg/kg. Plasma viral loads (PVL) were measured longitudinally and levels of cell-associated SIV-RNA and -DNA were quantified in resting CD4+ T-cells isolated from peripheral blood, lymph nodes (LN), spleen and bone marrow (BM). We performed flow cytometric analysis of T cell activation and assessed the gene expression profile and SIV-specific T-cell responses following AZD5582 treatment.
Treatment with AZD5582 resulted in efficient activation of ncNF-κB in absence of generalized T-cell activation in blood and LN. A persistent increase in PVL on ART was observed in 5/12 (42%) AZD5582-treated RM while PVL remained undetectable in 9 control animals. The episodes of viremia induced by AZD5582 started as soon as 48h after the first dose. Viremia >60 copies/ml was measured in 15/28 samples (53%) in a period of 10 weeks with levels reaching 1390 SIV-RNA copies/ml. The levels of cell-associated SIV-RNA in resting CD4+ T-cells isolated from LN were significantly higher in 10-dose AZD5582-treated animals vs. controls (p= 0.0157) and tended to also be higher in the spleen, but not blood or BM. The levels of SIV-DNA quantified in the same compartments were not significantly different between AZD5582-treated and control groups. Principal component analyses revealed a distinct impact of AZD5582 on the transcriptome of CD4+ T cells isolated from blood and LN pre- and post-treatment. SIV-specific T cell responses measured in blood and LN by ELISPOT were not negatively impacted by treatment with AZD5582.
Activating the ncNF-κB pathway in vivo with the SMACm AZD5582 resulted in high level and persistent induction of SIV-RNA expression in ART-suppressed RM in absence of generalized T-cell activation, indicative of latency reversal. Further studies will combine this promising LRA with immune clearance strategies to reduce viral reservoirs.