Application of infrared matrix-assisted laser desorption electrospray ionization mass spectrometry for morphine imaging in brain tissue.

Here, we present a method developed for the analysis of spatial distributions of morphine in mouse brain tissue using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) coupled to a Q Exactive Plus mass spectrometer. The method is also capable of evaluating spatial distributions of the antiretroviral drug abacavir. To maximize sensitivity to morphine, we analyze various Orbitrap mass spectrometry acquisition modes utilizing signal abundance and frequency of detection as evaluation criteria. We demonstrate detection of morphine in mouse brain and establish that the selected ion monitoring mode provides 2.5 times higher sensitivity than the full-scan mode. We find that distributions of morphine and abacavir are highly correlated with the Pearson correlation coefficient R = 0.87. Calibration showed that instrument response is linear up to 40 pg/mm2 (3.8 µg/g of tissue).

Feasibility, Acceptability and Appropriateness of MedViewer: A Novel Hair-Based Antiretroviral Real-Time Clinical Monitoring Tool Providing Adherence Feedback to Patients and Their Providers.

Antiretroviral therapy (ART) adherence is key to achieving viral load suppression and ending the HIV epidemic but monitoring and supporting adherence using current interventions is challenging. We assessed the feasibility, acceptability and appropriateness of MedViewer (MV), a novel intervention that provides real-time adherence feedback for patients and providers using infra-red matrix-assisted laser desorption electrospray ionization (IR-MALDESI) for mass spectrometry imaging of daily ART concentrations in patients' hair. We used mixed methods to feasibility test MV at a busy Infectious Diseases (ID) clinic, enrolling 16 providers and 36 patients. Providers underwent standardized training; patients and providers watched an 8-min informational video about MV. We collected patient and provider data at baseline and within 24 h of clinic visits and, with patients, approximately 1 month after clinic visits. MedViewer was feasible, liked by patients and providers, and perceived to help facilitate adherence conversations and motivate patients to improve adherence. Trial Registration: NCT04232540.

Mass spectrometry imaging of hair identifies daily maraviroc adherence in HPTN 069/ACTG A5305.

Objective measures of adherence for antiretrovirals used as pre-exposure prophylaxis (PrEP) are critical for improving preventative efficacy in both clinical trials and real-world application. Current objective adherence measures either reflect only recent behavior (eg days for plasma or urine) or cumulative behavior (eg months for dried blood spots). Here, we measured the accumulation of the antiretroviral drug maraviroc (MVC) in hair strands by infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) to evaluate adherence behavior longitudinally at high temporal resolution. An MSI threshold for classifying daily adherence was established using clinical samples from healthy volunteers following directly observed dosing of 1 to 7 doses MVC/week. We then used the benchmarked MSI assay to classify adherence to MVC-based PrEP regimens in hair samples collected throughout the 48-week HPTN069/ACTGA5305 study. We found that only ~32% of investigated hair samples collected during the study's active dosing period showed consistent daily PrEP adherence throughout a retrospective period of 30 days, and also found that profiles of daily individual adherence from MSI hair analysis could identify when patients were and were not taking study drug. The assessment of adherence from MSI hair strand analysis was 62% lower than adherence classified using paired plasma samples, the latter of which may be influenced by white-coat adherence. These findings demonstrate the ability of MSI hair analysis to examine daily variability of adherence behavior over a longer-term measurement and offer the potential for longitudinal comparison with risk behavior to target patient-specific adherence interventions and improve outcomes.

A Novel Algorithm to Improve PrEP Adherence Monitoring Using Dried Blood Spots.

Tenofovir diphosphate (TFVdp; an active metabolite of oral HIV pre-exposure prophylaxis (PrEP)) is measured in dried blood spots (DBS) to estimate adherence. However, TFVdp's long half-life in whole blood may lead to misclassification following a recent change in adherence. PrEP's other metabolite, emtricitabine triphosphate (FTCtp), has a shorter half-life in whole blood but adherence thresholds are undefined. We characterized DBS TFVdp and FTCtp concentrations across many dosing scenarios. Population pharmacokinetic models were fit to TFVdp and FTCtp DBS concentrations from a directly observed therapy study (NCT03218592). Concentrations were simulated for 90 days of daily dosing followed by 90 days of 1 to 7 doses/week and for event-driven PrEP (edPrEP) scenarios. Thresholds of 1,000 and 200 fmol/punch, for TFVdp and FTCtp, respectively, were reflective of taking 4 doses/week (a minimum target for effective PrEP in men). TFVdp was < 1,000 fmol/punch for 17 days after initiating daily PrEP and > 1,000 fmol/punch for 62 days after decreasing to 3 doses/week. Respectively, FTCtp was < 200 fmol/punch for 4 days and > 200 fmol/punch for 6 days. Accuracy of edPrEP adherence classification depended on duration between last sex act and DBS sampling for both measures with misclassification ranging from 9-100%. These data demonstrate adherence misclassification by DBS TFVdp for 2 months following a decline in adherence, elucidating the need for FTCtp to estimate recent adherence. We provide proof of principle that individualized interpretation is needed to support edPrEP adherence monitoring. Our collective approach facilitates clinicians' ability to interpret DBS results and administer patient-centric interventions.

Quantitative Imaging Analysis of the Spatial Relationship between Antiretrovirals, Reverse Transcriptase Simian-Human Immunodeficiency Virus RNA, and Fibrosis in the Spleens of Nonhuman Primates.

Although current antiretroviral therapy (ART) has increased life expectancy, a cure for human immunodeficiency virus (HIV) remains elusive due to the persistence of the virus in tissue reservoirs. In the present study, we sought to elucidate the relationship between antiretrovirals (ARVs) and viral expression in the spleen. We performed mass spectrometry imaging (MSI) of 6 different ARVs, RNAscope in situ hybridization of viral RNA, and immunohistochemistry of three different fibrosis markers in the spleens of 8 uninfected and 10 reverse transcriptase simian-human immunodeficiency virus (RT-SHIV)-infected rhesus macaques (infected for 6 weeks) that had been dosed for 10 days with combination ART. Using MATLAB, computational quantitative imaging analysis was performed to evaluate the spatial and pharmacological relationships between the 6 ARVs, viral RNA, and fibrotic deposition. In these spleens, >50% of the spleen tissue area was not covered by any detectable ARV response (any concentration above the limits of detection for individual ARVs). The median spatial ARV coverage across all tissues was driven by maraviroc followed by efavirenz. Yet >50% of RNA-positive cells were not exposed to any detectable ARV. Quantifiable maraviroc and efavirenz colocalization with RNA-positive cells was usually greater than the in vitro concentration inhibiting 50% replication (IC50). Fibrosis markers covered more than 50% of the spleen tissue area and had negative relationships with cumulative ARV coverages. Our findings suggest that a heterogeneous ARV spatial distribution must be considered when evaluating viral persistence in lymphoid tissue reservoirs.

Antiretroviral drug exposure in lymph nodes is heterogeneous and drug dependent.

INTRODUCTION: HIV reservoirs and infected cells may persist in tissues with low concentrations of antiretrovirals (ARVs). Traditional pharmacology methods cannot assess variability in ARV concentrations within morphologically complex tissues, such as lymph nodes (LNs). We evaluated the distribution of six ARVs into LNs and the proximity of these ARVs to CD4+ T cells and cell-associated RT-SHIV viral RNA. METHODS: Between December 2014 and April 2017, RT-SHIV infected (SHIV+; N = 6) and healthy (SHIV-; N = 6) male rhesus macaques received two selected four-drug combinations of six ARVs over 10 days to attain steady-state conditions. Serial cryosections of axillary LN were analysed by a multimodal imaging approach that combined mass spectrometry imaging (MSI) for ARV disposition, RNAscope in situ hybridization for viral RNA (vRNA) and immunohistochemistry for CD4+ T cell and collagen expression. Spatial relationships across these four imaging domains were investigated by nearest neighbour search on co-registered images using MATLAB. RESULTS: Through MSI, ARV-dependent, heterogeneous concentrations were observed in different morphological LN regions, such as the follicles and medullary sinuses. After 5-6 weeks of infection, more limited ARV penetration into LN tissue relative to the blood marker heme was found in SHIV+ animals (SHIV+: 0.7 [0.2-1.4] mm; SHIV-: 1.3 [0.5-1.7] mm), suggesting alterations in the microcirculation. However, we found no detectable increase in collagen deposition. Regimen-wide maps of composite ARV distribution indicated that up to 27% of SHIV+ LN tissue area was not exposed to detectable ARVs. Regions associated with B cell follicles had median 1.15 [0.94-2.69] -fold reduction in areas with measurable drug, though differences were only statistically significant for tenofovir (p = 0.03). Median co-localization of drug with CD4+ target cells and vRNA varied widely by ARV (5.1-100%), but nearest neighbour analysis indicated that up to 10% of target cells and cell-associated vRNA were not directly contiguous to at least one drug at concentrations greater than the IC50 value. CONCLUSIONS: Our investigation of the spatial distributions of drug, virus and target cells underscores the influence of location and microenvironment within LN, where a small population of T cells may remain vulnerable to infection and low-level viral replication during suppressive ART.

Mass Spectroscopy Imaging of Hair Strands Captures Short-Term and Long-Term Changes in Emtricitabine Adherence.

Most measures of adherence to antiretroviral therapy require a blood sample, and none capture longitudinal daily adherence. A new noninvasive method for measuring daily adherence to antiretroviral regimens containing emtricitabine (FTC) was developed for intact hair strands using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI). A directly observed therapy study of daily and intermittent (3, 1, and 0 doses/week) FTC dosing (n = 12) benchmarked adherence in hair, revealing distinct accumulation patterns and median FTC signal abundance (1,702, 495, 352, and 0, respectively) with each dosing frequency. A threshold value of FTCsignal abundance of 500 differentiated daily dosing from 3 or fewer doses/week (specificity, 100%; sensitivity, 100% over 30 days and 80% over 60 days). Using these criteria, daily FTC hair adherence was classified in young men (n = 8) who have sex with men (YMSM) engaged in or initiating preexposure prophylaxis (PrEP). Four types of adherence profiles were observed in sequential 30-day periods: consistently high, occasional missed doses, improvement following study initiation, and intermittent. Discrete days of nonadherence were identified across the 60-day window, with the average number of consecutive days classified as nonadherent increasing across the four profile types (1, 2, 19, and 58 days, respectively). Additionally, cumulative FTC response in hair (60-day average) significantly correlated with dried blood spot tenofovir diphosphate concentrations collected simultaneously (rs = 0.79, P = 0.03). Based on these data, IR-MALDESI FTC adherence classification in hair strands can better delineate short-term changes in adherence behaviors over a long retrospective window, offering great potential for noninvasive adherence monitoring and quick supportive interventions.

Drug-Dependent Morphological Transitions in Spherical and Worm-Like Polymeric Micelles Define Stability and Pharmacological Performance of Micellar Drugs.

Significant advances in physicochemical properties of polymeric micelles enable optimization of therapeutic drug efficacy, supporting nanomedicine manufacturing and clinical translation. Yet, the effect of micelle morphology on pharmacological efficacy is not adequately addressed. This work addresses this gap by assessing pharmacological efficacy of polymeric micelles with spherical and worm-like morphologies. It is observed that poly(2-oxazoline)-based polymeric micelles can be elongated over time from a spherical structure to worm-like structure, with elongation influenced by several conditions, including the amount and type of drug loaded into the micelles. The role of different morphologies on pharmacological performance of drug loaded micelles against triple-negative breast cancer and pancreatic cancer tumor models is further evaluated. Spherical micelles accumulate rapidly in the tumor tissue while retaining large amounts of drug; worm-like micelles accumulate more slowly and only upon releasing significant amounts of drug. These findings suggest that the dynamic character of the drug-micelle structure and the micelle morphology play a critical role in pharmacological performance, and that spherical micelles are better suited for systemic delivery of anticancer drugs to tumors when drugs are loosely associated with the polymeric micelles.

Quantitative Imaging Analysis of the Spatial Relationship between Antiretrovirals, Reverse Transcriptase Simian-Human Immunodeficiency Virus RNA, and Collagen in the Mesenteric Lymph Nodes of Nonhuman Primates.

Human immunodeficiency virus (HIV) persistence in tissue reservoirs is a major barrier to HIV cure. While antiretrovirals (ARVs) suppress viral replication, antiretroviral therapy (ART) interruption results in rapid rebound viremia that may originate from lymphoid tissues. To understand the relationship between anatomic distribution of ARV exposure and viral expression in lymph nodes, we performed mass spectrometry imaging (MSI) of 6 ARVs, RNAscope in situ hybridization for viral RNA (vRNA), and immunohistochemistry of collagen in mesenteric lymph nodes from 8 uninfected and 10 reverse transcriptase simian/human immunodeficiency virus (RT-SHIV)-infected rhesus macaques dosed to steady state with combination ART. MATLAB-based quantitative imaging analysis was used to evaluate spatial and pharmacological relationships between these ARVs, viral RNA (both vRNA+ cells and follicular dendritic cell [FDC]-bound virions), and collagen deposition. Using MSI, 31% of mesenteric lymph node tissue area was found to be not covered by any ARV. Additionally, 28% of FDC-trapped virions and 21% of infected cells were not exposed to any detected ARV. Of the 69% of tissue area that was covered by cumulative ART exposure, nearly 100% of concentrations were greater than in vitro 50% inhibitory concentration (IC50) values; however, 52% of total tissue coverage was from only one ARV, primarily maraviroc. Collagen covered ∼35% of tissue area but did not influence ARV distribution heterogeneity. Our findings are consistent with our hypothesis that ARV distribution, in addition to total-tissue drug concentration, must be considered when evaluating viral persistence in lymph nodes and other reservoir tissues.

Poly(2-oxazoline) nanoparticle delivery enhances the therapeutic potential of vismodegib for medulloblastoma by improving CNS pharmacokinetics and reducing systemic toxicity.

We report a nanoparticle formulation of the SHH-pathway inhibitor vismodegib that improves efficacy for medulloblastoma, while reducing toxicity. Limited blood-brain barrier (BBB) penetration and dose-limiting extitle/citraneural toxicities complicate systemic therapies for brain tumors. Vismodegib is FDA-approved for SHH-driven basal cell carcinoma, but implementation for medulloblastoma has been limited by inadequate efficacy and excessive bone toxicity. To address these issues through optimized drug delivery, we formulated vismodegib in polyoxazoline block copolymer micelles (POx-vismo). We then evaluated POx-vismo in transgenic mice that develop SHH-driven medulloblastomas with native vasculature and tumor microenvironment. POx-vismo improved CNS pharmacokinetics and reduced bone toxicity. Mechanistically, the nanoparticle carrier did not enter the CNS, and acted within the vascular compartment to improve drug delivery. Unlike conventional vismodegib, POx-vismo extended survival in medulloblastoma-bearing mice. Our results show the broad potential for non-targeted nanoparticle formulation to improve systemic brain tumor therapy, and specifically to improve vismodegib therapy for SHH-driven cancers.

Application of a Scavenger Receptor A1-Targeted Polymeric Prodrug Platform for Lymphatic Drug Delivery in HIV.

We have developed a macromolecular prodrug platform based on poly(l-lysine succinylated) (PLS) that targets scavenger receptor A1 (SR-A1), a receptor expressed by myeloid and endothelial cells. We demonstrate the selective uptake of PLS by murine macrophage, RAW 264.7 cells, which was eliminated upon cotreatment with the SR-A inhibitor polyinosinic acid (poly I). Further, we observed no uptake of PLS in an SR-A1-deficient RAW 264.7 cell line, even after 24 h incubation. In mice, PLS distributed to lymphatic organs following i.v. injection, as observed by ex vivo fluorescent imaging, and accumulated in lymph nodes following both i.v. and i.d. administrations, based on immunohistochemical analysis with high-resolution microscopy. As a proof-of-concept, the HIV antiviral emtricitabine (FTC) was conjugated to the polymer's succinyl groups via ester bonds, with a drug loading of 14.2% (wt/wt). The prodrug (PLS-FTC) demonstrated controlled release properties in vitro with a release half-life of 15 h in human plasma and 29 h in esterase-inhibited plasma, indicating that drug release occurs through both enzymatic and nonenzymatic mechanisms. Upon incubation of PLS-FTC with human peripheral blood mononuclear cells (PBMCs), the released drug was converted to the active metabolite FTC triphosphate. In a pharmacokinetic study in rats, the prodrug achieved ∼7-19-fold higher concentrations in lymphatic tissues compared to those in FTC control, supporting lymphatic-targeted drug delivery. We believe that the SR-A1-targeted macromolecular PLS prodrug platform has extraordinary potential for the treatment of infectious diseases.

Influence of hair treatments on detection of antiretrovirals by mass spectrometry imaging.

Analysis of drugs in hair by mass spectrometry imaging (MSI) has great potential as an objective, long-term measure of medication adherence. However, the fidelity of the chemical record in hair may be compromised by any cosmetic hair treatments. Here, we investigate infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) MSI response to multiple antiretrovirals (ARVs) in cosmetically treated hair. Hair strands from patients on different ARV regimens were mechanically treated with dye, bleach, and relaxer. The treatments had little or no effect relative to untreated controls for cobicistat, abacavir, dolutegravir, maraviroc, efavirenz, and darunavir, but all three treatments removed emtricitabine (FTC) to undetectable levels from patient hair strands. We also evaluated hair strands by IR-MALDESI MSI from 8 patients on FTC-based regimens who reported a range of hair treatments at varying recency prior to hair collection. While FTC was undetectable in the treated portion of these hair strands, ARVs coadministered with FTC remained detectable in hair strands after treatment. We conclude that IR-MALDESI MSI can be used when measuring adherence to ARV therapy, provided that ARVs other than FTC are targeted in people using hair treatments.

Using Real-Time Adherence Feedback to Enhance Communication About Adherence to Antiretroviral Therapy: Patient and Clinician Perspectives.

New technologies for real-time adherence monitoring hold the potential to enhance antiretroviral therapy adherence interventions by providing objective information about daily medication-taking behavior. To realize this potential, we need to understand how to integrate real-time adherence feedback into existing best practices to promote antiretroviral therapy adherence at the point of care. Using in-depth interviews with 30 HIV-infected patients and 29 HIV care clinicians, our primary aims were to understand patients' and clinicians' perceptions of anticipated benefits and preferred uses of objective feedback to enhance conversations about adherence and to identify concerns about the impact of objective monitoring on patient-clinician relationships and communication. Both patients and clinicians suggested that identifying patterns of nonadherence with real-time feedback could (a) facilitate collaborative adherence problem-solving, (b) motivate patient adherence, and (c) reinforce the importance of optimal adherence. Some clinicians worried that delivery of real-time feedback could imply mistrust of patient-reported adherence and suggested careful framing of monitoring results. A few patients and clinicians were concerned that negative reactions to monitoring could discourage retention in care and reduce adherence motivation. These results indicate the potential of real-time feedback to enhance existing evidence-based adherence interventions targeting the key adherence precursors of adherence information, motivation, and behavioral skills. Guidance for the delivery of real-time adherence feedback should focus on both optimizing adherence and mitigating negative perceptions of adherence monitoring.

scRNA-seq in medulloblastoma shows cellular heterogeneity and lineage expansion support resistance to SHH inhibitor therapy.

Targeting oncogenic pathways holds promise for brain tumor treatment, but inhibition of Sonic Hedgehog (SHH) signaling has failed in SHH-driven medulloblastoma. Cellular diversity within tumors and reduced lineage commitment can undermine targeted therapy by increasing the probability of treatment-resistant populations. Using single-cell RNA-seq and lineage tracing, we analyzed cellular diversity in medulloblastomas in transgenic, medulloblastoma-prone mice, and responses to the SHH-pathway inhibitor vismodegib. In untreated tumors, we find expected stromal cells and tumor-derived cells showing either a spectrum of neural progenitor-differentiation states or glial and stem cell markers. Vismodegib reduces the proliferative population and increases differentiation. However, specific cell types in vismodegib-treated tumors remain proliferative, showing either persistent SHH-pathway activation or stem cell characteristics. Our data show that even in tumors with a single pathway-activating mutation, diverse mechanisms drive tumor growth. This diversity confers early resistance to targeted inhibitor therapy, demonstrating the need to target multiple pathways simultaneously.

Antiretroviral Penetration across Three Preclinical Animal Models and Humans in Eight Putative HIV Viral Reservoirs.

For HIV cure strategies like "kick and kill" to succeed, antiretroviral (ARV) drugs must reach effective concentrations in putative viral reservoirs. We characterize penetration of six ARVs in three preclinical animal models and humans. We found that standard dosing strategies in preclinical species closely mimicked tissue concentrations in humans for some, but not all, ARVs. These results have implications for interpreting HIV treatment, prevention, or cure interventions between preclinical and clinical models.

Heterogeneous antiretroviral drug distribution and HIV/SHIV detection in the gut of three species.

HIV replication within tissues may increase in response to a reduced exposure to antiretroviral drugs. Traditional approaches to measuring drug concentrations in tissues are unable to characterize a heterogeneous drug distribution. Here, we used mass spectrometry imaging (MSI) to visualize the distribution of six HIV antiretroviral drugs in gut tissue sections from three species (two strains of humanized mice, macaques, and humans). We measured drug concentrations in proximity to CD3+ T cells that are targeted by HIV, as well as expression of HIV or SHIV RNA and expression of the MDR1 drug efflux transporter in gut tissue from HIV-infected humanized mice, SHIV-infected macaques, and HIV-infected humans treated with combination antiretroviral drug therapy. Serial 10-µm sections of snap-frozen ileal and rectal tissue were analyzed by MSI for CD3+ T cells and MDR1 efflux transporter expression by immunofluorescence and immunohistochemistry, respectively. The tissue slices were analyzed for HIV/SHIV RNA expression by in situ hybridization and for antiretroviral drug concentrations by liquid chromatography-mass spectrometry. The gastrointestinal tissue distribution of the six drugs was heterogeneous. Fifty percent to 60% of CD3+ T cells did not colocalize with detectable drug concentrations in the gut tissue. In all three species, up to 90% of HIV/SHIV RNA was found to be expressed in gut tissue with no exposure to drug. These data suggest that there may be gut regions with little to no exposure to antiretroviral drugs, which may result in low-level HIV replication contributing to HIV persistence.

Infrared Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging of Human Hair to Characterize Longitudinal Profiles of the Antiretroviral Maraviroc for Adherence Monitoring.

Here, we assess infrared matrix assisted laser desorption electrospray ionization (IR-MALDESI) mass spectrometry imaging (MSI) analysis of hair as a clinical tool for monitoring patient adherence to the antiretroviral maraviroc (MVC). A custom MATLAB-based algorithm has been developed to streamline data analysis and generate longitudinal profiles of drug incorporation along the length of hair strands. Hair strands from volunteers enrolled in a directly observed therapy study were analyzed by IR-MALDESI MSI and processed using this tool to characterize the profiles of single doses and a daily dose regimen of MVC. Single dose responses were 1.7 [1.1, 2.5] mm (median [range]) wide along the length of the hair and were detected in 8 out of 12 volunteers. Daily dose profiles capturing 28 days of continuous dosing were approximately 5 times the intensity of single dose profiles and 10.5 [7.0, 13] mm wide, corresponding to 1 month of hair growth. MVC ion abundance was observed in all 12 volunteers for the daily dosing period. Daily dosing profiles were consistent with a model of MVC accumulation in hair based on linear superposition of a single dose response, indicating the potential for prediction of daily drug-taking behavior based on deconvolution of a complex longitudinal profile in hair.

Patient and clinician perspectives on optimizing graphical displays of longitudinal medication adherence data.

OBJECTIVE: New pharmacological measures assessing medication adherence, including longitudinal drug levels in hair, are emerging. Little is known, however, about how best to present results from such measures to patients and clinicians in comprehensive, easy-to-understand, acceptable formats. We, therefore, developed three graphical display prototypes of hypothetical daily drug concentrations measured in hair, and assessed their acceptability among participants. METHODS: We interviewed 30 HIV-positive patients and 29 clinicians to examine perceived acceptability for each graphical display prototype. RESULTS: Patients and clinicians generally found the prototypes acceptable for facilitating understanding of patient adherence; however, areas for optimization were identified. For patients with lower health literacy, prototypes did not provide sufficient understanding of the link between medication-taking and drug concentrations in hair. These patients also preferred pictographs over bar or line graphs. Clinicians largely preferred daily drug concentration data in bar graphs with information included about the measure's accuracy. Participants questioned the utility of showing drug concentrations above a therapeutic range, though they found color-coding results acceptable. CONCLUSIONS: Assessing prototype versions of graphical displays of hypothetical longitudinal adherence data indicated ways to optimize their acceptability. PRACTICE IMPLICATIONS: Acceptable prototype-tested graphical displays of longitudinal patient-specific drug concentrations may enhance adherence monitoring in clinical settings.

Antiretroviral concentrations and surrogate measures of efficacy in the brain tissue and CSF of preclinical species.

1. Antiretroviral concentrations in cerebrospinal fluid (CSF) are used as surrogate for brain tissue, although sparse data support this. We quantified antiretrovirals in brain tissue across preclinical models, compared them to CSF, and calculated 90% inhibitory quotients (IQ90) for nonhuman primate (NHP) brain tissue. Spatial distribution of efavirenz was performed by mass-spectrometry imaging (MSI). 2. HIV or RT-SHIV-infected and uninfected animals from two humanized mouse models (hemopoietic-stem cell/RAG2-, n = 36; bone marrow-liver-thymus/BLT, n =13) and an NHP model (rhesus macaque, n =18) were dosed with six antiretrovirals. Brain tissue, CSF (NHPs), and plasma were collected at necropsy. Drug concentrations were measured by LC-MS/MS. Rapid equilibrium dialysis determined protein binding in NHP brain. 3. Brain tissue penetration of most antiretrovirals were >10-fold lower (p < 0.02) in humanized mice than NHPs. NHP CSF concentrations were >13-fold lower (p <0.02) than brain tissue with poor agreement except for efavirenz (r = 0.91, p = 0.001). Despite 97% brain tissue protein binding, efavirenz achieved IQ90>1 in all animals and 2-fold greater white versus gray matter concentration. 4. Brain tissue penetration varied across animal models for all antiretrovirals except raltegravir, and extrapolating brain tissue concentrations between models should be avoided. With the exception of efavirenz, CSF is not a surrogate for brain tissue concentrations.