Selected drugs with reported secondary cell-differentiating capacity prime latent HIV-1 infection for reactivation

Reactivation of latent HIV-1 infection is considered our best therapeutic means to eliminate the latent HIV-1 reservoir. Past therapeutic attempts to systemically trigger HIV-1 reactivation using single drugs were unsuccessful. We thus sought to identify drug combinations consisting of one component that would lower the HIV-1 reactivation threshold and a synergistic activator. With aclacinomycin and dactinomycin, we initially identified two FDA-approved drugs that primed latent HIV-1 infection in T cell lines and in primary T cells for reactivation and facilitated complete reactivation at the population level. This effect was correlated not with the reported primary drug effects but with the cell-differentiating capacity of the drugs. We thus tested other cell-differentiating drugs/compounds such as cytarabine and aphidicolin and found that they also primed latent HIV-1 infection for reactivation. This finding extends the therapeutic promise of N'-N'-hexamethylene-bisacetamide (HMBA), another cell-differentiating agent that has been reported to trigger HIV-1 reactivation, into the group of FDA-approved drugs. To this end, it is also noteworthy that suberoylanilide hydroxamic acid (SAHA), a polar compound that was initially developed as a second-generation cell-differentiating agent using HMBA as a structural template and which is now marketed as the histone deacetylase (HDAC) inhibitor vorinostat, also has been reported to trigger HIV-1 reactivation. Our findings suggest that drugs with primary or secondary cell-differentiating capacity should be revisited as HIV-1-reactivating agents as some could potentially be repositioned as candidate drugs to be included in an induction therapy to trigger HIV-1 reactivation.