Methylation profiles predict ATI outcome in the kick-and-kill therapeutic vaccine BCN02 clinical trial [EPIC array]

BCN02 was an exploratory, single arm study designed to evaluate a kick-and-kill therapeutic vaccine strategy in early-treated HIV infected individuals. The participants in the study received a MVA.HIVconsv vaccination before and after three cycles of infusion of romidepsin (RMD), an inhibitor of histone deacetylases that acts as a viral latency reversing agent. The inclusion of a monitored antiretroviral pause (MAP) identified 8 individuals with an early viral rebound (pVL > 2,000 HIV RNA copies/mL, < 4 weeks of MAP initiation) and 4, with a late viral rebound (pVL > 2,000 HIV RNA copies/mL, > 4 weeks of MAP initiation). In the present study, a systems biology analysis was conducted to identify the pathways modulated at transcriptomic and epigenetic level during the clinical intervention, involving vaccination and RMD, and to identify biomarkers predictive of HIV viral rebound during MAP. To this end, we studied gene expression and whole-genome DNA methylation in longitudinal PBMC samples prior and after the intervention. The main impact on host transcriptional and epigenetic signatures was observed after vaccination and RMD infusion (Vacc+RMD) with multiple pathways related to HIV infection and immune response showing changes at gene expression and DNA methylation level. Analysis of an independent cohort of individuals treated with RMD alone, showed that these changes were mainly driven by CD4 T cells. DNA methylation patterns in full PBMC obtained after full intervention (Vacc+RMD) allowed to discriminate individuals with an Early versus Late viral rebound. These individuals also showed a differential enrichment on chromatin accessibility and transcription factor binding sites. Intriguingly, 30 of the DMPs between Early and Late rebounders at Vacc+RMD were present already at baseline and were more accentuated after RMD infusion. Overall, this study provides with a deeper understanding of the mechanisms modulated during the BCN02 study and highlights the importance of DNA methylation profiles in HIV cure. DNA methylation in 32 PBMCs samples from 15 individuals toatl was assessed with the Illumina EPIC array in three timepoints: before cART intiation (only in 6 out of 15 individuals), at MAP timepoint (14 individuals) and 24 weeks after cART resumption (12 individuals).