Assessing Time-to-Treatment Variability in Antiretroviral Penetration by Multimodal Imaging - ABSTRACT HIV remains persistently detectable within tissues during antiretroviral treatment (ART) and can rebound throughout the body following a treatment interruption. Low concentrations of antiretrovirals (ARVs) may be present within these tissue viral reservoirs, such as lymph nodes, which may provide localized sanctuaries for virus. Understanding the potential role of pharmacology in the persistence of virus during treatment and subsequent viral reactivation following treatment interruption is critical for targeting strategies to achieve a functional cure. This remains a knowledge gap because of existing limitations in measuring tissue ARV concentrations by standard LC-MS/MS methods. These methods cannot capture variability in drug penetration within the tissue microenvironment that may limit exposure to cells targeted by virus. We have developed a new approach for quantifying ARVs in tissues based on IR-MALDESI MSI, which offers the ability to map spatial distributions of drugs. Using this approach we have demonstrated heterogeneous ARV distributions, often detected as monotherapy, across a range of putative reservoir tissues. We hypothesize that progressive HIV pathogenesis can induce structural and morphological modifications in tissue (e.g. fibrosis) that may limit penetration of ART to some T cell populations within reservoir tissues. To investigate this question, we will combine multiple cutting-edge imaging techniques to simultaneously characterize and quantify distributions of drug, virus, and host response within tissues of a rhesus macaque (RM) animal model using a well-characterized SIV strain that provides a robust, predictable pathogenic response. With long-acting injections (LAI) emerging as an alternative to daily therapy, this effort will investigate differences in ARV tissue penetration through each of these two routes of administration. Three specific aims are proposed: 1) Characterize tissue PK using IR- MALDESI MSI in reservoir tissues following treatment initiation in acute or late chronic infection. 2) Use a novel multimodal spatial imaging suite (IR-MALDESI MSI, RNAscope in situ hybridization, spatial transcriptomics) to evaluate differences in tissue PK/PD based on timing of treatment initiation. 3) Identify lipidomic/metabolomic markers of immune responses in tissue by IR-MALDESI MSI and develop an innovative single-assay approach to tissue PK/PD assessment. When completed, this proposal will benchmark PK of long-acting and daily treatment combinations for the first time in healthy RM and assess how the extent of immunopathogenic damage prior to treatment initiation influences ARV tissue penetration. These data will provide insight into how delivery of new therapies LAI strategies can optimize clinical outcomes
