22:T49a,IL-15 is under clinical investigation toward the goal of curing HIV infection because of its abilities to reverse HIV latency and enhance immune effector function. However, increased potency through combination with other agents may be needed. 3-Hydroxy-1,2,3-benzotriazin-4(3H)-one (HODHBt) enhances IL-15-mediated latency reversal and NK cell function by increasing STAT5 activation. We hypothesized that HODHBt would also synergize with IL-15, via STAT5, to directly enhance HIV-specific cytotoxic T cell responses. We showed that ex vivo IL-15 + HODHBt treatment markedly enhanced HIV-specific granzyme B-releasing T cell responses in PBMCs from antiretroviral therapy-suppressed (ART-suppressed) donors. We also observed upregulation of antigen processing and presentation in CD4+ T cells and increased surface MHC-I. In ex vivo PBMCs, IL-15 + HODHBt was sufficient to reduce intact proviruses in 1 of 3 ART-suppressed donors. Our findings reveal the potential for second-generation IL-15 studies incorporating HODHBt-like therapeutics. Iterative studies layering on additional latency reversal or other agents are needed to achieve consistent ex vivo reservoir reductions.23:T4d4,Persistent HIV reservoirs in CD4⁺ T cells pose a barrier to curing HIV infection. We identify overexpression of enhancer of zeste homolog 2 (EZH2) in HIV-infected CD4⁺ T cells that survive cytotoxic T lymphocyte (CTL) exposure, suggesting a mechanism of CTL resistance. Inhibition of EZH2 with the US Food and Drug Administration-approved drug tazemetostat increases surface expression of major histocompatibility complex (MHC) class I on CD4⁺ T cells, counterbalancing HIV Nef-mediated MHC class I downregulation. This improves CTL-mediated elimination of HIV-infected cells and suppresses viral replication in vitro. In a participant-derived xenograft mouse model, tazemetostat elevates MHC class I and the pro-apoptotic protein BIM in CD4⁺ T cells, facilitating CD8⁺ T cell-mediated reductions of HIV reservoir seeding. Additionally, tazemetostat promotes sustained skewing of CD8⁺ T cells toward less-differentiated and exhausted phenotypes. Our findings reveal EZH2 overexpression as a mechanism of CTL resistance and support the clinical evaluation of tazemetostat as a method of enhancing clearance of HIV reservoirs and improving CD8⁺ T cell function.

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