Interleukin 6 Blockade With Tocilizumab Diminishes Indices of Inflammation That Are Linked to Mortality in Treated Human Immunodeficiency Virus Infection.

BACKGROUND: People with human immunodeficiency virus (PWH) are at increased risk for comorbidities, and plasma interleukin 6 (IL-6) levels are among the most robust predictors of these outcomes. Tocilizumab (TCZ) blocks the receptor for IL-6, inhibiting functions of this cytokine. METHODS: This was a 40-week, placebo-controlled, crossover trial (NCT02049437) where PWH on stable antiretroviral therapy (ART) were randomized to receive 3 monthly doses of TCZ or matching placebo intravenously. Following a 10-week treatment period and a 12-week washout, participants were switched to the opposite treatment. The primary endpoints were safety and posttreatment levels of C-reactive protein (CRP) and CD4+ T-cell cycling. Secondary endpoints included changes in inflammatory indices and lipid levels. RESULTS: There were 9 treatment-related toxicities of grade 2 or greater during TCZ administration (mostly neutropenia) and 2 during placebo administration. Thirty-one of 34 participants completed the study and were included in a modified intent-to-treat analysis. TCZ reduced levels of CRP (median decrease, 1819.9 ng/mL, P < .0001; effect size, 0.87) and reduced inflammatory markers in PWH, including D-dimer, soluble CD14, and tumor necrosis factor receptors. T-cell cycling tended to decrease in all maturation subsets after TCZ administration, but was only significant among naive CD4 T cells. Lipid levels, including lipid classes that have been related to cardiovascular disease risk, increased during TCZ treatment. CONCLUSIONS: TCZ is safe and decreases inflammation in PWH; IL-6 is a key driver of the inflammatory environment that predicts morbidity and mortality in ART-treated PWH. The clinical significance of lipid elevations during TCZ treatment requires further study. Clinical Trials Registration. NCT02049437.

An Integrated DAIDS Laboratory Oversight Framework: Application of the DAIDS GCLP Guidelines.

The Division of AIDS (DAIDS) Good Clinical Laboratory Practice (GCLP) Guidelines establish a framework to guide the oversight of laboratories supporting DAIDS-sponsored clinical research or trials. Compliance with these guidelines promotes data reliability, consistency, validity, and the safety of the clinical research or trial participants and laboratory staff, as well as ensures adherence to regulatory requirements. This article describes the application of the DAIDS GCLP Guidelines, the DAIDS Integrated Laboratory Oversight Framework, and the coordinated efforts of the collaborative oversight team of laboratory experts to support and monitor the performance of over 175 participating laboratories worldwide. Data from two self-administered online surveys conducted in 2017 and 2023 assessed the laboratory staff's experience implementing the GCLP Guidelines. The results of the 2017 survey were instrumental in informing changes to GCLP audit activities and promoting harmonization in the approach to laboratory oversight. A key finding from the 2023 survey results is the preference for hybrid GCLP training encompassing face-to-face and online modules. Overall, both surveys acknowledged satisfaction with applying and implementing GCLP Guidelines. The need to effectively disseminate information about DAIDS laboratory oversight requirements to support the improved implementation of GCLP Guidelines was notable from both survey results. The collaborative team of laboratory experts and the integrated oversight approach promote knowledge-sharing and accountability to support the application of the GCLP Guidelines and compliance monitoring. The systematic implementation of the integrated laboratory oversight activities helped identify valuable lessons for improving laboratory performance and opportunities to strengthen quality oversight for laboratories participating in clinical research or trials. .

Eliminating perinatal HIV in the United States: mission possible?

: In 2015, only 53 infants born in the United States acquired HIV - the lowest recorded number of perinatal HIV infections. Recognizing this significant achievement, we must acknowledge that the United States has not yet reached the goal of eliminating perinatal HIV transmission. This analysis describes different approaches to perinatal HIV preventive services among five states and the District of Columbia as case studies. Continuous focus on improving identification, surveillance and prevention of HIV infection in pregnant women and their infants is necessary to reach the goal of eliminating perinatal HIV transmission in the United States.

Peripheral arterial occlusive disease: global gene expression analyses suggest a major role for immune and inflammatory responses.

BACKGROUND: Peripheral arterial disease (PAD), a major manifestation of atherosclerosis, is associated with significant cardiovascular morbidity, limb loss and death. However, mechanisms underlying the genesis and progression of the disease are far from clear. Genome-wide gene expression profiling of clinical samples may represent an effective approach to gain relevant information. RESULTS: After histological classification, a total of 30 femoral artery samples, including 11 intermediate lesions, 14 advanced lesions and 5 normal femoral arteries, were profiled using Affymetrix microarray platform. Following real-time RT-PCR validation, different algorithms of gene selection and clustering were applied to identify differentially expressed genes. Under a stringent cutoff, i.e., a false discovery rate (FDR) <0.5%, we found 366 genes were differentially regulated in intermediate lesions and 447 in advanced lesions. Of these, 116 genes were overlapped between intermediate and advanced lesions, including 68 up-regulated genes and 48 down-regulated ones. In these differentially regulated genes, immune/inflammatory genes were significantly up-regulated in different stages of PAD, (85/230 in intermediate lesions, 37/172 in advanced lesions). Through literature mining and pathway analysis using different databases such as Gene Ontology (GO), and the Kyoto Encyclopedia of Gene and Genomics (KEGG), genes involved in immune/inflammatory responses were significantly enriched in up-regulated genes at different stages of PAD(p < 0.05), revealing a significant correlation between immune/inflammatory responses and disease progression. Moreover, immune-related pathways such as Toll-like receptor signaling and natural killer cell mediated cytotoxicity were particularly enriched in intermediate and advanced lesions (P < 0.05), highlighting their pathogenic significance during disease progression. CONCLUSION: Lines of evidence revealed in this study not only support previous hypotheses, primarily based on studies of animal models and other types of arterial disease, that inflammatory responses may influence the development of PAD, but also permit the recognition of a wide spectrum of immune/inflammatory genes that can serve as signatures for disease progression in PAD. Further studies of these signature molecules may eventually allow us to develop more sophisticated protocols for pharmaceutical interventions.

Virological Suppression and Patterns of Resistance Amongst Patients on Antiretroviral Therapy at 4 Nigerian Military Hospitals.

BACKGROUND: In resource-constrained settings, plasma HIV-1 RNA quantification has not been routinely available for the monitoring of response to antiretroviral therapy. This study evaluated virological suppression rates amongst patients on first-line ART in four Nigerian military hospitals. METHODS: We conducted a cross-sectional study of 325 randomly selected adult clinic clients (≥18 years old) on first-line ART regimens at four Nigerian military hospitals. Plasma HIV-1 RNA was assayed using a Roche COBAS TaqMan48 with High Pure System. Virological failure was defined as HIV-1 RNA >1000 copies/ml. Specimens with HIV-1 RNA >1000 copies/ml were referred for genotyping. RESULTS: HIV-1 RNA results were obtained in 322 participants. Two hundred and seventy-eight study participants (86.3%) had HIV viral RNA < 1000 copies/ml, including 273 (84.8%) with HIV- 1 RNA <400 copies/ml. HIV drug resistance genotyping results were obtained in 35 of 44 study participants with HIV-1 RNA >1000 copies/ml. Only 14% (5/35) had no resistance mutations. Of the remainder, 10% (3/30) had no nucleoside analogue mutations while 33% (10/30) had only M184V along with non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations (K103N or Y188C). 25% (5/25) of participants failing on Zidovudine had more than two thymidine analogue mutations (TAMs). CONCLUSION: We observed a high virological suppression rate among the study participants. However, a large proportion of virologically unsuppressed clients had identifiable resistance mutations. The study demonstrates that viral load monitoring is feasible at Nigerian military hospitals and supports the current WHO HIV treatment guidelines which emphasize virological monitoring of patients on ART for early detection of treatment failure.

HIV birth testing and linkage to care for HIV-infected infants.

: On 5-6 May 2016, the division of AIDS of the National Institute of Allergy and Infectious Diseases convened a workshop on 'HIV Birth Testing and Linkage to Care for HIV Infected Infants.' The goal of the workshop was to evaluate birth testing for early infant diagnosis (EID) of HIV, delineate technological resources for advancing a point-of-care (POC) HIV test implementable at birth and chart out the implementation hurdles for initiating early antiretroviral therapy to HIV-infected infants diagnosed at birth. The workshop addressed research and regulatory needs involved in the optimization of POC EID testing and challenges associated with implementation of EID, focusing on testing at birth. Scientific gaps and areas of intervention to accelerate and scale-up EID initiatives and birth testing were identified. These include discussion of the evidence supporting an early mortality peak among HIV-infected infant and justifying a role for birth HIV testing, including POC testing; evaluation of the current POC EID technology pipeline and test performance characteristics required for effective programmatic uptake; mathematical modeling of different testing scenarios and solutions with inclusion of birth testing; the adoption of setting-specific EID testing algorithms to achieve efficient linkage to care including early antiretroviral therapy initiation; the development of appropriate quality assurance programs to ensure accuracy of test results and enable sustainability of the testing program. Addressing these gaps and answering these challenges will be important in helping improve outcomes for HIV-infected infants and accelerate achieving the Joint United Nations Program for HIV and AIDS 90-90-90 targets in children.

Sigma-2 receptor agonists activate a novel apoptotic pathway and potentiate antineoplastic drugs in breast tumor cell lines.

We have reported previously that sigma-2 receptors are expressed in high densities in a variety of tumor cell types (B. J. Vilner et al., Cancer Res., 55: 408-413, 1995) and that various sigma ligands have cytotoxic effects (B. J. Vilner et al., J. Neurosci., 15: 117-134, 1995). Other investigators have demonstrated increased expression of sigma-2 receptors in rapidly proliferating tumors (R. H. Mach et al., Cancer Res., 57: 156-161, 1997) and the ability of some sigma ligands to inhibit proliferation (P. J. Brent and G. T. Pang, Eur. J. Pharmacol., 278: 151-160, 1995). We demonstrate here the ability of sigma-2 receptor agonists to induce cell death by a mechanism consistent with apoptosis. In breast tumor cell lines that are sensitive (MCF-7) and resistant (MCF-7/Adr-, T47D, and SKBr3) to antineoplastic agents, incubation with the sigma-2 subtype-selective agonists CB-64D and CB-184 produced dose-dependent cytotoxicity (measured by lactate dehydrogenase release into medium). The EC(50) for this response was similar across cell lines, irrespective of p53 genotype and drug-resistance phenotype. CB-64D and the subtype nonselective sigma-2 agonists haloperidol and reduced haloperidol induced terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining in MCF-7 and T47D cells, indicating that cell death occurs via apoptosis. Apoptosis was also indicated by increases in Annexin V binding caused by CB-64D. In MCF-7 cells, cytotoxicity and Annexin V binding induced by the antineoplastics doxorubicin and actinomycin D was partially or completely abrogated by certain specific and general inhibitors of caspases. In contrast, caspase inhibitors had no effect on sigma-2 receptor-mediated (CB-64D and CB-184) cytotoxicity or Annexin V binding. Marked potentiation of cytotoxicity was observed when a subtoxic dose of CB-184 was combined with doxorubicin or actinomycin D, both in drug-sensitive (MCF-7) and drug-resistant (MCF-7/Adr-) cell lines. Haloperidol potentiated doxorubicin only in drug-resistant cells. These findings suggest the involvement of a novel p53- and caspase-independent apoptotic pathway used by sigma-2 receptors, which is distinct from mechanisms used by some DNA-damaging, antineoplastic agents and other apoptotic stimuli. These observations further suggest that sigma-2 receptors may be targets that can be therapeutically exploited in the treatment of both drug-sensitive and drug-resistant metastatic tumors.

sigma(2) Receptors regulate changes in sphingolipid levels in breast tumor cells.

sigma(2) Receptors induce apoptosis in various cell types. The sphingolipid, ceramide as well as the sphingoid bases are involved in cell proliferation. Sphingolipids of MCF-7/Adr- and T47D breast tumor cells were metabolically radiolabeled. The sigma(2) receptor agonists (+)-1R,5R-E-8-(3,4-dichlorobenzylidene)-5-(3-hydroxyphenyl)-2-methylmorphan-7-one (CB-184) and 1S,2R-(--)-cis-N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)-cyclohexylamine (BD737) caused dose-dependent increases in [(3)H]ceramide, with concomitant decreases in [(3)H]sphingomyelin. Both effects were attenuated by the novel sigma(2) receptor antagonist, N-phenethylpiperidine oxalate (AC927). sigma(2) Receptors may produce effects on cell growth and apoptosis by regulating the sphingolipid pathway.

Short communication: east meets west: a description of HIV-1 drug resistance mutation patterns of patients failing first line therapy in PEPFAR clinics from Uganda and Nigeria.

HIV-1 viral load (VL) monitoring is recommended but seldom performed in resource-constrained countries. An evaluation of patients receiving first-line antiretroviral therapy in a multicountry PEPFAR program (RV288) was performed to determine the rates and predictors of virologic suppression. Resistance data from treatment failures are available from Uganda and Nigeria. Each country enrolled 325 subjects into this cross-sectional study. Subjects on first-line therapy were randomly selected for HIV RNA testing (viral load). Regimens included efavirenz or nevirapine with zidovudine/lamivudine or tenofovir/lamivudine. VL was determined from plasma using the Roche COBAS TaqMan HIV-1 Test, High Pure System v1.0 (47 copies/ml). Genotypic resistance testing was performed on samples with VL>1,000 copies/ml. From Uganda, 85% of subjects were undetectable while 7% (23/325) had VL>1,000 copies/ml. The HIV-1 subtype distribution was as follows: A=47.6%, C=14.3%, and D=38.1%. No resistance mutations were found in 14% of subjects. All subjects with resistance had the M184V mutation. Of subjects failing a zidovudine regimen less than 1 year, 88% (7/8) had no thymidine analogue mutations (TAMs), compared to 50% (4/8) failing greater than 1 year. Four subjects (25%) had more than two mutations from the TAM-1 pathway (41L, 210W, 215Y). In Nigeria, 82% were undetectable while 14% (45/325) had VL>1,000 copies/ml. HIV-1 subtype distribution was as follows: 62.8%=CRF02_AG, 34%=pure G, and 2.8%=A. Of the 35 genotyped subjects, 14% (5/35) had no resistance mutations. Of the remainder, 10% (3/30) had no nucleoside analogue mutations while 33% (10/30) had only M184V along with nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations. Forty percent (10/25) of subjects on zidovudine failed without TAMs. Another 25% (5/25) of subjects failing on zidovudine had more than two TAM-1 mutations. Individuals failing first-line antiretroviral therapy (ART) may retain sensitivity to one or more nucleoside analogues from the regimen. Knowledge of drug resistance patterns allow for selection of drugs that can be recycled in future regimens. Accumulation of resistance mutations may compromise future treatment options.

Occurrence of etravirine/rilpivirine-specific resistance mutations selected by efavirenz and nevirapine in Kenyan patients with non-B HIV-1 subtypes failing antiretroviral therapy.

Resistance to efavirenz and nevirapine has not been associated with mutations at position 138 of reverse transcriptase. In an evaluation of virologic suppression rates in PEPFAR (President's Emergency Plan For AIDS Relief) clinics in Kenya among patients on first-line therapy (RV288), 63% (617/975) of randomly selected patients on antiretroviral therapy were suppressed (HIV RNA<400 copies/ml). Among those with non-nucleoside reverse transcriptase inhibitor resistance (n = 101), 14 (13.8%) had substitutions at 138 (A, G, K or Q), mutations selected only by etravirine and rilpivirine in subtype B viruses. All 14 patients received efavirenz or nevirapine, not etravirine or rilpivirine, and were predominantly subtype A1. This may be the first report of efavirenz and nevirapine selecting these mutations in these subtypes.

Lipodystrophy and inflammation predict later grip strength in HIV-infected men: the MACS Body Composition substudy.

Body fat changes in HIV-infected persons are associated with increased systemic inflammation and increased mortality. It is unknown whether lipodystrophy is also associated with declines in physical function. Between 2001 and 2003, 33 HIV-infected men with evidence of lipodystrophy (LIPO⁺), 23 HIV-infected men without lipodystrophy (LIPO⁻), and 33 seronegative men were recruited from the Multicenter AIDS Cohort Study (MACS) for the Body Composition substudy. Visceral adipose tissue (VAT) was assessed by quantitative computed tomography. Lean body mass (LBM) and extremity fat were measured by dual-energy x-ray absorptiometry. Insulin resistance was estimated by Homeostatic Model Assessment (HOMA). Serum interleukin (IL)-6, soluble tumor necrosis factor (TNF)-α receptors I and II (sTNFRI and sTNFRII), and highly sensitive C-reactive protein (hs-CRP) concentrations were quantified from archived serum samples. These measurements were correlated with grip strength measured in 2007 using linear regression. At the substudy visit, the LIPO⁺ group had higher HOMA, sTNFRI, sTNFRII, and IL-6 levels than the LIPO⁻ group. In 2007, the LIPO⁺ group had lower median grip strength than the LIPO⁻ group (34.4 vs. 42.7 kg, p=0.002). Multivariable analysis of HIV⁺ men showed older age, lower LBM, higher sTNFRII concentrations, and LIPO⁺ status [adjusted mean difference -4.9 kg (p=0.045)] at the substudy visit were independently associated with lower subsequent grip strength. Inflammation, lower LBM, and lipodystrophy in HIV-infected men were associated with lower subsequent grip strength. These findings suggest that inflammation may contribute to declines in functional performance, independent of age.

Optimising the manufacture, formulation, and dose of antiretroviral drugs for more cost-efficient delivery in resource-limited settings: a consensus statement.

It is expected that funding limitations for worldwide HIV treatment and prevention in resource-limited settings will continue, and, because the need for treatment scale-up is urgent, the emphasis on value for money has become an increasing priority. The Conference on Antiretroviral Drug Optimization--a collaborative project between the Clinton Health Access Initiative, the Johns Hopkins University School of Medicine, and the Bill & Melinda Gates Foundation--brought together process chemists, clinical pharmacologists, pharmaceutical scientists, physicians, pharmacists, and regulatory specialists to explore strategies for the reduction of antiretroviral drug costs. The antiretroviral drugs discussed were prioritised for consideration on the basis of their market impact, and the objectives of the conference were framed as discussion questions generated to guide scientific assessment of potential strategies. These strategies included modifications to the synthesis of the active pharmaceutical ingredient (API) and use of cheaper sources of raw materials in synthesis of these ingredients. Innovations in product formulation could improve bioavailability thus needing less API. For several antiretroviral drugs, studies show efficacy is maintained at doses below the approved dose (eg, efavirenz, lopinavir plus ritonavir, atazanavir, and darunavir). Optimising pharmacoenhancement and extending shelf life are additional strategies. The conference highlighted a range of interventions; optimum cost savings could be achieved through combining approaches.

Induction of antitumor immunity ex vivo using dendritic cells transduced with fowl pox vector expressing MUC1, CEA, and a triad of costimulatory molecules (rF-PANVAC).

The fowl pox vector expressing the tumor-associated antigens, mucin-1 and carcinoembryonic antigen in the context of costimulatory molecules (rF-PANVAC) has shown promise as a tumor vaccine. However, vaccine-mediated expansion of suppressor T-cell populations may blunt clinical efficacy. We characterized the cellular immune response induced by ex vivo dendritic cells (DCs) transduced with (rF)-PANVAC. Consistent with the functional characteristics of potent antigen-presenting cells, rF-PANVAC-DCs demonstrated strong expression of mucin-1 and carcinoembryonic antigen and costimulatory molecules, CD80, CD86, and CD83; decreased levels of phosphorylated STAT3, and increased levels of Tyk2, Janus kinase 2, and STAT1. rF-PANVAC-DCs stimulated expansion of tumor antigen-specific T cells with potent cytolytic capacity. However, rF-PANVAC-transduced DCs also induced the concurrent expansion of FOXP3 expressing CD4CD25 regulatory T cells (Tregs) that inhibited T-cell activation. Moreover, Tregs expressed high levels of Th2 cytokines [interleukin (IL)-10, IL-4, IL-5, and IL-13] together with phosphorylated STAT3 and STAT6. In contrast, the vaccine-expanded Treg population expressed high levels of Th1 cytokines IL-2 and interferon-γ and the proinflammatory receptor-related orphan receptor γt (RORγt) and IL-17A suggesting that these cells may share effector functions with conventional TH17 T cells. These data suggest that Tregs expanded by rF-PANVAC-DCs, exhibit immunosuppressive properties potentially mediated by Th2 cytokines, but simultaneous expression of Th1 and Th17-associated factors suggests a high degree of plasticity.

The use of computational fluid dynamic models for the optimization of cell seeding processes.

The seeding of a porous scaffold with stem cells is a fundamental step in engineering sizeable tissue constructs that are clinically viable. However, a key problem often encountered is inhomogeneous seeding of the cells particularly when the cells are delivered through the thickness of the scaffold. The objective of this study was to establish the quantitative relationships between the cell seeding efficiency and the initial vacuum pressure in a compact perfusion seeding device that uses the effect of differential pressure induced by vacuum to seed cells on a porous scaffold. A transient CFD solution of the fluid flow in the device was used to optimize the initial vacuum pressure for efficient cell seeding. Results indicate that the optimal initial vacuum pressure for homogenous cell seeding is approximately -20 kPa for the seeding device. This study presents a 3-D computational model that can be employed in designing and optimizing cell seeding techniques and corresponding technology.

Pharmacokinetic/pharmacodynamic modeling of the antiretroviral activity of the CCR5 antagonist Vicriviroc in treatment experienced HIV-infected subjects (ACTG protocol 5211).

OBJECTIVE: This substudy of AIDS Clinical Trials Group (ACTG) Protocol 5211 explored the relationship between antiretroviral effect and plasma concentrations of vicriviroc, an investigational CCR5 antagonist for HIV infection. METHODS: Eighty-six treatment-experienced subjects failing their current antiretroviral regimens were randomized to add vicriviroc 5, 10, or 15 mg once daily or placebo for 2 weeks. Beyond week 2, subjects were changed to optimized background antiretroviral treatment while continuing vicriviroc or placebo. Plasma samples collected at weeks 2 and 8 were assayed for vicriviroc concentrations and combined with vicriviroc concentration data from 110 seronegatives enrolled in 5 phase 1 studies. An inhibitory Emax model was used to assess pharmacokinetic (PK)/pharmacodynamic relationships and recursive partitioning was applied to determine the breakpoint in vicriviroc PK parameters associated with virologic suppression. RESULTS: A 2-compartment model was fitted to the drug concentration data. At week 2, a higher vicriviroc Cmin was associated with a greater mean drop in HIV RNA (viral load) and a higher percentage of subjects experiencing a >1 log10 copies/mL drop in viral load. In subjects with Cmin > 54 ng/mL, the mean viral load decrease was 1.35 log10 copies/mL vs. 0.76 log10 with Cmin < 54 ng/mL (P = 0.003, Student t test). At this Cmin breakpoint, 70% of subjects with the higher Cmin had a >1 log drop in HIV RNA, compared with 44% with a lower Cmin (P = 0.048, Fisher exact test). Similar results were seen with an area under the curve breakpoint of 1460 ng h/mL. At weeks 16 and 24, all vicriviroc-treated subjects experienced better viral load responses than placebo recipients, but there was no apparent relationship between PK and change in viral load among these vicriviroc-treated subjects. CONCLUSIONS: There was a positive correlation between vicriviroc Cmin, area under the curve, and viral load changes at week 2 in treatment-experienced HIV-infected subjects receiving no other new active antiretroviral drugs. This correlation did not persist beyond week 16, probably because treatment response at that point also depended on having other active drugs in the regimen.

Age-related changes in plasma concentrations of the HIV protease inhibitor lopinavir.

The advent of highly active antiretroviral therapy in the treatment of HIV disease has substantially extended the lifespan of individuals infected with HIV resulting in a growing population of older HIV-infected individuals. The efficacy and safety of antiretroviral agents in the population are important concerns. There have been relatively few studies assessing antiretroviral pharmacokinetics in older patients. Thirty-seven subjects aged 18-30 years and 40 subjects aged 45-79 years, naive to antiretroviral therapy, received lopinavir/ritonavir (400/100) bid, emtricitibine 200 mg qd, and stavudine 40 mg bid. Trough lopinavir concentrations were available for 44 subjects, collected at 24, 36, and 96 weeks. At week 24, older age was associated with higher lopinavir trough concentrations, and a trend was observed toward older age being associated with higher lopinavir trough concentrations when all time points were evaluated. In the young cohort, among subjects with two or more measurements, there was a trend toward increasing intrasubject trough lopinavir concentrations over time. Using a nonlinear, mixed-effects population pharmacokinetic model, age was negatively associated with lopinavir clearance after adjusting for adherence. Adherence was assessed by patient self-reports; older patients missed fewer doses than younger patients (p = 0.02). No difference in grade 3-4 toxicities was observed between the two age group. Older patients have higher trough lopinavir concentrations and likely decreased lopinavir clearance. Age-related changes in the pharmacokinetics of antiretroviral drugs may be of increasing importance as the HIV-infected population ages and as older individuals comprise an increasing proportion of new diagnoses.