A Subcutaneous Implant of Tenofovir Alafenamide Fumarate Causes Local Inflammation and Tissue Necrosis in Rabbits and Macaques.
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SUBMITTER: Su JT
PROVIDER: S-EPMC7038301 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The administration of antiretrovirals (ARVs) for HIV pre-exposure prophylaxis (PrEP) is highly efficacious and may benefit from new long-acting (LA) drug delivery approaches. This paper describes a subcutaneous, reservoir-style implant for the LA delivery of tenofovir alafenamide (TAF) and documents the preclinical assessment of implant safety and pharmacokinetics (PK) in New Zealand White (NZW) rabbits (3 groups of n = 5), beagle dogs (2 groups of n = 6), and rhesus macaques (2 groups of n = 3). Placebo implants were placed in rabbits (n = 10) and dogs (n = 12). Implant parameters, including selection of the TAF form, choice of excipient, and PCL formulation were tuned to achieve targeted concentrations of the active anabolite of TAF, tenofovir diphosphate (TFV-DP), within peripheral blood mononuclear cells (PBMCs) and mucosal tissues relevant to HIV transmission. Sustained concentrations of TFV-DP in PBMCs over 100 fmol/106 cells were achieved in all animal species indicating that the implants effectively delivered TAF for 3-6 months. Unlike placebo implants without TAF, all active implants resulted in local adverse events (AEs) proximal to the implant ranging in severity from mild to moderate and included dermal inflammation and necrosis across all species. Despite these AEs, the implant performed as designed and achieved a constant drug release profile, supporting the continued development of this drug delivery platform.
| S-EPMC9343794 | biostudies-literature
Project description:PurposeSexual transmission of HIV has been clinically proven to be preventable with a once-daily oral tablet; however, missed doses dramatically increase the risk of HIV infection. Long-acting subcutaneous implants do not allow the user to miss a dose. A desirable long-acting drug-eluting implant can deliver a constant amount of drug, adjust the delivered dose, and be readily manufactured. We present a long-acting, subcutaneous implant design composed of tenofovir alafenamide hemifumarate (TAF) pellets loaded in a sealed polyether urethane tube for the prevention of HIV transmission.MethodsImplants were prepared with pressed drug pellets and extruded polyurethane tubing. In vitro release rate of implants using different pellet formulations, rate-controlling membranes, and geometries were measured.ResultsTenofovir alafenamide release appeared to be governed by a pseudo-steady state and followed a mass transport model of release from a cylindrical drug reservoir. Implant seal integrity was tested and confirmed using mechanical testing. The inclusion of sodium chloride in the pellet increased the release rate and reduced initial lag. The release was sustained for 100 days.ConclusionsThe release rate of tenofovir alafenamide mechanistically varied with geometry and rate controlling membrane composition. The polyether urethane implant presented herein is modular and tunable to adjust the release rate and duration of the TAF release.
| S-EPMC7160069 | biostudies-literature
Project description:HIV-1 is a chronic disease managed by strictly adhering to daily antiretroviral therapy (ART). However, not all people living with HIV-1 have access to ART, and those with access may not adhere to treatment regimens increasing viral load and disease progression. Here, a subcutaneous nanofluidic implant was used as a long-acting (LA) drug delivery platform to address these issues. The device was loaded with tenofovir alafenamide (TAF) and implanted in treatment-naïve simian HIV (SHIV)-positive nonhuman primates (NHP) for a month. We monitored intracellular tenofovir-diphosphate (TFV-DP) concentration in the target cells, peripheral blood mononuclear cells (PBMC). The concentrations of TFV-DP were maintained at a median of 391.0 fmol/106 cells (IQR, 243.0 to 509.0 fmol/106 cells) for the duration of the study. Further, we achieved drug penetration into lymphatic tissues, known for persistent HIV-1 replication. Moreover, we observed a first-phase viral load decay of -1.14 ± 0.81 log10 copies/mL (95% CI, -0.30 to -2.23 log10 copies/mL), similar to -1.08 log10 copies/mL decay observed in humans. Thus, LA TAF delivered from our nanofluidic implant had similar effects as oral TAF dosing with a lower dose, with potential as a platform for LA ART.
| S-EPMC7590004 | biostudies-literature
Project description:Long-acting (LA) administration using a subcutaneous (s.c.) implant presents opportunities to simplify administration of antiretroviral drugs, improve pharmacological profiles, and overcome suboptimal adherence associated with daily oral formulations. Tenofovir alafenamide (TAF) is a highly potent nucleoside reverse transcriptase inhibitor (NRTI) and an attractive agent for LA delivery, with a high potency and long intracellular half-life. The aim of this study was to predict minimum TAF doses required to achieve concentrations effective for HIV preexposure prophylaxis (PrEP). Daily drug release requirements were then ascertained by averaging across the dosing interval. A TAF physiologically based pharmacokinetic (PBPK) model was developed and partially qualified against available oral single- and multiple-dose pharmacokinetics. The models were assumed to be qualified when simulated values were within 2-fold of the observed mean. TAF s.c. implants were simulated in five hundred individuals, reporting predicted TAF plasma and tenofovir (TFV) plasma concentrations for various release rates. Intracellular TFV diphosphate (TFV-DP) concentrations were also simulated in peripheral blood cells and cervical and rectal tissues. The minimum dose predicted to achieve intracellular TFV-DP levels above a target concentration of 48 fmol/106 cells for a month was identified. TAF, TFV, and TFV-DP concentrations for release rates between 1.0 and 1.6 mg/day were simulated. The PBPK model indicated that a minimum release of 1.4 mg/day TAF is necessary to achieve TFV-DP concentrations above the identified target in peripheral blood mononuclear cells (PBMCs). TFV-DP cervical and rectal tissue concentrations were predicted to be between 1.5 and 2.0 fmol/106 cells and 0.9 and 1.1 fmol/106 cells, respectively, for release rates between 1.3 and 1.6 mg/day. These simulations provide target minimum doses for LA TAF PrEP in humans. Based on the generated results, multiple implants delivering a total of 1.4 mg/day of TAF subcutaneously could provide protection levels for approximately 6 months to 1 year. This modeling may inform future design of s.c. implants to mitigate adherence issues for effective PrEP applications.
| S-EPMC7526822 | biostudies-literature
Project description:Pre-exposure prophylaxis (PrEP) using antiretroviral oral drugs is effective at preventing HIV transmission when individuals adhere to the dosing regimen. Tenofovir alafenamide (TAF) is a potent antiretroviral drug, with numerous long-acting (LA) delivery systems under development to improve PrEP adherence. However, none has undergone preventive efficacy assessment. Here we show that LA TAF using a novel subcutaneous nanofluidic implant (nTAF) confers partial protection from HIV transmission. We demonstrate that sustained subcutaneous delivery through nTAF in rhesus macaques maintained tenofovir diphosphate concentration at a median of 390.00 fmol/106 peripheral blood mononuclear cells, 9 times above clinically protective levels. In a non-blinded, placebo-controlled rhesus macaque study with repeated low-dose rectal SHIVSF162P3 challenge, the nTAF cohort had a 62.50% reduction (95% CI: 1.72% to 85.69%; p=0.068) in risk of infection per exposure compared to the control. Our finding mirrors that of tenofovir disoproxil fumarate (TDF) monotherapy, where 60.00% protective efficacy was observed in macaques, and clinically, 67.00% reduction in risk with 86.00% preventive efficacy in individuals with detectable drug in the plasma. Overall, our nanofluidic technology shows potential as a subcutaneous delivery platform for long-term PrEP and provides insights for clinical implementation of LA TAF for HIV prevention.
| S-EPMC8114879 | biostudies-literature
Project description:BackgroundTopical on-demand forms for HIV pre-exposure prophylaxis (PrEP) may be a desirable alternative for people that prefer not to use daily PrEP. CONRAD has developed inserts containing tenofovir alafenamide (TAF) and elvitegravir (EVG) for on-demand vaginal or rectal pericoital use. We assessed the pharmacokinetics (PK) and pre-exposure efficacy of rectally applied TAF/EVG inserts in macaques.MethodsPK was assessed in 12 pigtailed macaques. Tenofovir (TFV) and EVG levels were assayed in rectal biopsies and secretions, and tenofovir-diphosphate (TFV-DP) levels in biopsies and peripheral blood mononuclear cells (PBMC). Drug biodistribution was evaluated in 10 animals at necropsy 4 h post-dosing. For efficacy assessments, one or two TAF/EVG inserts were administered to macaques (n = 6) 4 h before repeated rectal SHIV162p3 challenges.FindingsOne TAF/EVG insert resulted in rapid and high EVG and TFV-DP in rectal tissue 4 h after application. Adding a second insert led to a 10-fold increase in EVG and TFV-DP in rectal tissue. Efficacy of one and two TAF/EVG inserts were 72.6% (CI 24.5%-92.6%) and 93.1% (CI 73.3%-99.2%), respectively.InterpretationAlthough high TFV-DP and EVG levels were observed with one rectal TAF/EVG insert, it only conferred partial protection from rectal SHIV challenges. Adding a second insert led to an increase in TFV and EVG in rectal tissues resulting in higher (>90%) efficacy. These results highlight the high efficacy of TAF/EVG inserts as topical on-demand rectal PrEP, as well as the need for appropriate drug coverage in the deep rectum and colon to achieve high protection.FundingThe work related to animal studies was funded by CDC intramural funds and an interagency agreement between CDC and USAID (USAID/CDC IAA AID-GH-T-15-00002). The work related to the insert formulation was funded by U.S. PEPFAR through USAID under a Cooperative Agreement (AID-OAA-A-14-00010) with CONRAD/Eastern Virginia Medical School. The findings and conclusions of this manuscript are those of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention (CDC), USAID, President's Emergency Plan for AIDS Relief (PEPFAR), Eastern Virginia Medical School (EVMS), or the US government.
| S-EPMC9643401 | biostudies-literature
Project description:BackgroundIn human immunodeficiency virus (HIV) treatment, tenofovir alafenamide (TAF) is associated with greater increases in all fasting cholesterol subgroups compared with tenofovir disoproxil fumarate (TDF). Because lipid abnormalities may contribute to cardiovascular morbidity and mortality, cardiovascular risk assessment is integral to routine HIV care. This post hoc study evaluates the impact of lipid changes on predicted atherosclerotic cardiovascular disease (ASCVD) risk and statin eligibility in treatment-naive adults living with HIV treated with TAF or TDF.MethodsParticipants (N = 1744) were randomized (1:1) to initiate TAF or TDF, each coformulated with elvitegravir/cobicistat/emtricitabine (studies GS-US-292-0104 and GS-US-292-0111). Eligibility for statin therapy and estimated 10-year ASCVD risk among adults aged 40-79 years treated with TAF or TDF for 96 weeks (W96) were analyzed based on American College of Cardiology/American Heart Association Pooled Cohort Equations. Categorical shifts in 10-year ASCVD risk from <7.5% to ≥7.5% by W96 on TAF versus TDF were calculated.ResultsParticipants initiating TAF versus TDF in the overall study population showed small but significant increases in median fasting lipid parameters at W96, including total cholesterol (191 vs 177 mg/dL; P < .001), low-density lipoprotein ([LDL] 119 vs 112 mg/dL; P < .001), and high-density lipoprotein ([HDL] 51 vs 48 mg/dL; P < .001), respectively. At baseline, 18% and 23% on TAF versus TDF had a 10-year ASCVD risk score ≥7.5%, with mean risk scores low overall for TAF versus TDF at baseline (4.9% vs 5.4%; P = .35) and W96 (6.1% vs 6.2%; P = .04). Increases in ASCVD risk from baseline to W96 were driven by both increasing age and changes in total cholesterol (TC) and HDL cholesterol. At W96, TC/HDL ratios (median) were 3.7 for both groups (P = .69). There was no difference between shifts in categorical risk for TAF versus TDF (9% vs 5%; P = .19). Eligibility for high-intensity statin therapy were similar for TAF versus TDF groups (19% vs 21%; P = .47).ConclusionsLipid changes with TAF as part of coformulated regimens do not substantively affect CVD risk profiles compared with TDF.
| S-EPMC6954396 | biostudies-literature
Project description:BackgroundInitiation of antiretroviral therapy (ART) and subsequent virologic suppression reduces immune activation and systemic inflammation.MethodsWe examined longitudinal changes in biomarkers of monocyte activation (sCD14, sCD163), and systemic (IL-6, hsCRP, sTNFR-I and D-dimer) and vascular (Lp-PLA2) inflammation in a subgroup (N=100 per arm) of participants enrolled in a randomized, placebo-controlled trial comparing elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (E/C/F/TAF; TAF) to E/C/F/tenofovir disoproxil fumarate (E/C/F/TDF; TDF) in treatment-naïve adults.ResultsFor 194 participants (TAF, 98; TDF, 96), baseline levels of biomarkers did not differ by treatment arm; there were no differences in biomarker values between groups at weeks 12, 24, or 48 (p>0.05), except IL-6 at week 12 (p=0.012). Among all participants (combining groups), there were statistically significant declines from baseline observed for D-dimer, sCD163, and sTNFR-1 by week 12 and IL-6 by week 24. The proportion of participants with Lp-LA2 levels<200ng per mL (p=0.250) or hsCRP levels <3000mg per L (p=0.586) was unchanged through week 48.ConclusionsWe observed equivalent declines in biomarkers of monocyte activation and systemic inflammation in treatment-naïve adults treated with TAF or TDF for 48weeks, suggesting that TAF and TDF have equivalent impact on immune activation and inflammation.
| S-EPMC5264242 | biostudies-literature
Project description:BackgroundBecause tenofovir alafenamide (TAF) leads to significantly lower plasma tenofovir concentrations than tenofovir disoproxil fumarate (TDF) and is a stronger substrate for P-glycoprotein (P-gp) than TDF, TAF could lead to decreased central nervous system (CNS) tenofovir exposure than TDF. We aimed to determine if switching from TDF to TAF increases the risk of neuronal injury, by quantifying plasma levels of neurofilament light protein (NfL), a sensitive marker of neuronal injury in HIV CNS infection.MethodsPlasma NfL concentration was measured at baseline, week 24, and week 84 in stored plasma samples from 416 participants (272 switching to elvitegravir (E)/cobicistat (C)/emtricitabine (F)/TAF and 144 continuing E/C/F/TDF) enrolled in the randomized, active-controlled, multicenter, open-label, noninferiority Gilead GS-US-292-0109 trial.ResultsWhile plasma NfL levels in both groups were within the normal range, we found a small but significant decrease in the E/C/F/TAF arm after 84 weeks from a geometric mean of 9.3 to 8.8 pg/mL (5.4% decline, 95% CI 2.0-8.4, p = 0.002). This change was significantly different (p = 0.001) from that of the E/C/F/TDF arm, in which plasma NfL concentration changed from 9.7 pg/mL at baseline to 10.2 pg/mL at week 84 (5.8% increase, 95% CI -0.8-12.9, p = 0.085). This increase is in line with what could be expected in normal ageing. Plasma NfL concentrations significantly correlated with age. No correlation was found between plasma NfL and serum creatinine.ConclusionsWe found no biomarker evidence of CNS injury when switching from TDF to TAF. It is unclear whether the small decrease in plasma NfL found after switch to TAF is of any clinical relevance, particularly with plasma NfL levels in both arms remaining within the limits found in HIV-negative controls. These results indicate that switching from TDF to TAF appears safe with regard to neuronal injury.
| S-EPMC6905536 | biostudies-literature
Project description:The secondary lymphoid tissues (LT), lymph nodes (LN) and gut-associated lymphoid tissue are the primary sites of HIV replication and where the latent pool of virus is maintained. We compared the pharmacokinetics of tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide (TAF) in LT of 13 HIV-infected persons receiving a TDF-containing antiretroviral regimen who subsequently switched to a TAF-containing regimen. Study participants were on stable antiretroviral therapy for ≥12 months with plasma HIV-RNA < 48 copies/mL for 6 months before enrollment and entry CD4 cell counts > 300 cells/µL. Intracellular concentrations of tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP) were quantified in PBMCs and in mononuclear cells obtained from LN, ileum and rectal tissues. With TAF, the TFV-DP concentrations in PBMCs and LN were 7.3-fold and 6.4-fold higher (ratios of geometric means of TAF to TDF), respectively, compared with TDF; ileal and rectal concentrations, however, were lower with geometric mean ratios of 0.14 and 0.18, respectively. A statistically significant relationship was observed between PBMC and LN concentrations of TFV-DP. During TDF-containing therapy, the expected effect of cobicistat to increase TFV plasma concentrations was observed, as were higher TFV-DP concentrations in PBMCs and mononuclear cells from LN, ileum and rectal tissues. The higher TFV-DP concentrations achieved with TAF in the LN provides the first human correlate of the observation in animals that TAF produced higher tenofovir LN concentrations. The ability to increase LN concentrations allows investigations of whether antiretroviral regimens with improved LN pharmacokinetics elicit a more complete virologic response in that compartment.
| S-EPMC7935460 | biostudies-literature