e dual reporter virus, exposure to apg - 1387 is accompanied by a reduction in the frequency of latently infected cells ( figure 2 ) without a detectable change in the level of cells supporting ltr - directed transcription. the data suggest that the latent cells might be preferentially targeted for elimination without reactivation in contrast to pma and ionomycin stimulation. this said, given the intrinsic properties of sms, we cannot completely exclude the possibility that there was no change in the frequency of reactivated cells because latently infected cells rapidly die after reactivation. consistent with previous works with other sms including azd5582 24 and ciapavir, 25 apg - 1387 induces detection of viremia, albeit modestly, in art - suppressed hu - mice as early as 48 h after treatment. importantly, in mice treated with multiple doses of apg - 1387, the proportion of cells carrying the integrated hiv dna was meaningfully reduced, suggesting that the bivalent apg - 1387 might preferentially target latently infected cells directly or indirectly for death ( figure 4 ). in addition, in apg - 1387 - treated mice the fact that the viral rebound was consistently lower throughout the ati and plateaued at a level below pre - art further strengthens the notion that apg - 1387 impacts negatively the pool of vrs ( figure 6 ). it is conceivable that such an impact is significant considering the modest effect of apg - 1387 on latency reversal in this experimental condition and the limited functional immune clearance mechanisms present in hu - blt mice. this said, further experimentation with a larger group of animals analyzed at endpoint is needed to confirm the modulatory role of apg - 1387 on vrs. a more detailed analysis gauging the effect of apg - 1387 on different cd4 + t cell subsets revealed a potential modulation of splenic th17 - like cells and foxp3 - expressing cd4 + t cells. we observe a trend toward a reduction in th17 - cell frequency in both art - suppressed mice treated in vivo with apg - 1387 and in art - naive infected mice whose splenocytes were stimulated ex vivo with apg - 1387 ( figure 5 ). since th17 cells have been proposed to be an important source of hiv latent reservoirs [ reviewed in53 ], a decrease in th17 cells might suggest a reduction in the level of integrated hiv dna - harboring cells, an observation that was made with apg - 1387 treated mice ( figure 4 ). regarding foxp3 - expressing cd4 + t cells in the spleen, there was no significant difference between art - suppressed mice treated with apg - 1387 or with the vehicle control. however, ex vivo stimulation of splenocytes from art - naive, hiv - infected mice with apg - 1387 modestly decreased the number of p24 - expressing foxp3 + cd4 + t cells, although the difference was not statistically significant. whether the non - canonical nfkb pathway is more functional in certain memory cd4 + t cell subsets remains to be fully elucidated. the fact that the central memory subset has been shown to require strong tcr - mediated signaling for maintenance suggests a more important role of the canonical nfkb pathway in this context [ reviewed in26, 54, 55 ]. taken together, these results highlight the importance of evaluating the potential effects of sms on various immune subsets known to be susceptible to hiv. our study shows that apg - 1387 has the capability to reactivate hiv, activate markers of apoptosis in latently infected cells, and reduce vrs without causing global t cell activation. however, the findings also underscore the need to combine bivalent sms with other therapeutics to improve the reactivation and elimination of vrs. indeed, recent findings have shown that combined panobinostat and pegylated interferon alpha 2 can transform the vr landscape through latency reversal and innate immune activation. 56 star★methods experimental model and study participant details experimental design no randomization and / or stratification was performed. hu - mice with variable levels of human cd45 + cells were equally distributed among experimental groups. all efforts were made to have equal or comparable number of mice or samples ( i. e., number of n ) per experimental group or condition. the exact number of n was provided in relevant figure legends. experimenters were blinded during processing biological samples, conducting experiments and analyzing samples in different assays. no inclusion or exclusion criteria were applied to the study. no statistical methods were used to pre - determine strategies for randomization and / or stratification, population size, inclusion and exclusion of any data or subjects, or whether the data met assumptions of the statistical approach. pharmacological and toxicity analysis hu - blt mice were left untreated or treated via intraperitoneal route ( ip ) with either vehicle - ( 10 % sterile cremophor dissolved in 5 % polyethylene glyco l - 400 and 85 % pbs ) or 20 mg / kg ( 100 apg - 1387 ( ascentage pharma, china ) every third day ( maximum 100 μl injection volume ) for up to 4 weeks. plasma was collected at different intervals and white blood cells isolated by treating whole blood with red blood cell lysis buffer ( invitrogen, u. s. a ). cells from blood and tissues were analyzed by flow cytometry as described in section ‘ flow cytometry ’ below for the effect of apg - 1387 on cell proliferation and activation. proinflammatory cytokines were evaluated in plasma of healthy untreated, apg - 1387 - and vehicle - treated hu - blt mice using legend max enzyme - linked immunosorbent assay ( elisa ) kits for human tnf and il6 ( both from biolegend, u. s. a ) as per the manufacturer ’ s protocol. data analysis was performed using graphpad prism software ( version 8. 0 ). quantification and statistical analysis flow cytometry data were analyzed using flowjo ( versions 9. 9. 3 and 10. 1 ). quantification of western blots was performed using imagej software. data analysis and presentation was done using graphpad prism ( version 8. 0 ). experimenters were blinded during data analysis of samples. descriptive measures ( mean, median, minimum / maximum range, 95 % confidence intervals, and percent ) were used to summarize the data and illustrate in graphical presentations. all statistical analysis was done using graphpad prism ( version 8. 0 ). nonparametric ( unpaired ) mann - whitney ’ s u - test ( two - tailed ) was conducted to compare ranks between two experimental groups ( e. g., treated with vehicle or with apg - 1387 ). nonparametric ( paired ) wilcoxon test was performed to compare the ranks of two matched samples ( e. g., before and after treatment with apg - 1387 ). when comparing multiple groups, non - parametric tests kruskal - wallis or friedman were performed and followed by dunn ’ s multiple comparison test ( e. g., vehicle - treated group compared to those treated with different concentrations of apg - 1387 or combined pma and ionomycin; effect of apg - 1387 on viral rebound at different time points post treatment interruption ). a p value of less than 0. 05 was considered statistically significant. ns, ∗, ∗∗, ∗∗∗, signify not significant, figure 2, the exact p values were ∗p = 0. 026, ∗∗p = 0. 007, ∗∗∗p = 0. 0004. in the two - tailed mann - whitney unpaired rank test shown in figure 3, the ∗p value was 0. 0286 while in figure 4, the p values were as follows: ∗p = 0. 0317 and ∗∗p = 0. 0043. for figure s6, the ∗p value was no statistical methods were used to pre - determine strategies for randomization and / or stratification, population size, inclusion and exclusion of any data or subjects, or whether the data met assumptions of the statistical approach. all software used in data analysis along with statistical parameters were mentioned in the appropriate figure legends. details about the statistical tests, exact values of n and definitions of the n were as indicated in the legend for each relevant figure.