Reduced darunavir dose is as effective in maintaining HIV suppression as the standard dose in virologically suppressed HIV-infected patients: a randomized clinical trial

Transfer of antiretroviral drugs into breastmilk: a prospective study from the Swiss Mother and Child HIV Cohort Study

INTRODUCTION

In 2018, Switzerland changed its guidelines to support women living with HIV wishing to breastfeed. The exposure of antiretroviral drugs (ARVs) in breastmilk and the ingested daily dose by the breastfed infant are understudied, notably for newer ARVs. This study aimed to quantify ARV concentrations in maternal plasma and breastmilk to determine the milk/plasma ratio, to estimate daily infant ARV dose from breastfeeding and to measure ARV concentrations in infants.

METHODS

All women wishing to breastfeed were included, regardless of their ARV treatment. Breastmilk and maternal plasma samples were mostly collected at mid-dosing interval.

RESULTS

Twenty-one mother/child pairs were enrolled; of those several were on newer ARVs including 10 raltegravir, 1 bictegravir, 2 rilpivirine, 2 darunavir/ritonavir and 3 tenofovir alafenamide. No vertical HIV transmission was detected (one infant still breastfed). The median milk/plasma ratios were 0.96/0.39 for raltegravir once/twice daily, 0.01 for bictegravir, 1.08 for rilpivirine, 0.12 for darunavir/ritonavir and 4.09 for tenofovir alafenamide. The median estimated infant daily dose (mg/kg) from breastfeeding was 0.02/0.25 for raltegravir once/twice daily, 0.01 for bictegravir, 0.02 for rilpivirine, 0.05 for darunavir/ritonavir and 0.007 for tenofovir alafenamide, resulting in relative infant dose <10% exposure index for all ARVs.

CONCLUSIONS

ARVs were transferred to a variable extent in breastmilk. Nevertheless, the estimated daily ARV dose from breastfeeding remained low. Differential ARV exposure was observed in breastfed infants with some ARVs being below/above their effective concentrations raising the concern of resistance development if HIV infection occurs. More data on this potential risk are warranted to better support breastfeeding.

Exploration of Reduced Doses and Short-Cycle Therapy for Darunavir/Cobicistat in Patients with HIV Using Population Pharmacokinetic Modeling and Simulations

BACKGROUND AND OBJECTIVES

Protease inhibitors such as darunavir are an important therapeutic option in the anti-human immunodeficiency virus arsenal. Current dosage guidelines recommend using cobicistat- or ritonavir-boosted darunavir 800 mg every 24 h (q24h) in protease inhibitor-naïve patients, or ritonavir-boosted darunavir 600 mg q12h in experienced patients. However, darunavir displays a large, poorly characterized, inter-individual pharmacokinetic variability. The objectives of this study were to investigate the pharmacokinetics of darunavir and to elucidate the sources of its inter-individual variability using population pharmacokinetic modeling. Then, to determine the appropriateness of current treatment guidelines and the feasibility of alternative dosing regimens in a representative cohort of adult patients using simulations.

METHODS

Sparse pharmacokinetic samples were collected in 127 patients with human immunodeficiency virus type 1 infection, then supplemented with rich sampling data from a subset of 12 individuals. Data were analyzed using the nonlinear mixed-effects modeling software NONMEM. The effect of reduced doses (600 mg q24h and 400 mg q24h) or reduced frequency of administration (800 mg q24h for 5 days followed by 2 days of treatment interruption) was simulated.

RESULTS

Our model adequately described the pharmacokinetics of darunavir. Predictors of individual exposure were CYP3A5*3 and SLCO3A1 rs8027174 genotypes, sex, and alpha-1 acid glycoprotein level. No relationship was apparent between darunavir area under the curve and treatment efficacy or safety. For reduced dose regimens, darunavir concentrations remained above the protein binding-corrected EC₅₀ in the majority of subjects. More stringent pharmacokinetic targets were not reached in a significant proportion of patients.

CONCLUSIONS

These results add to the growing body of evidence that darunavir-based therapy could be simplified to reduce costs and toxicity, as well as to improve patient compliance. However, the heterogeneity in pharmacokinetic response should be considered when assessing whether individual patients could benefit from a particular regimen, for instance through the use of population pharmacokinetic models.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03101644, date of registration: 5 April, 2017.

Efficacy and safety of a single-tablet regimen containing tenofovir disoproxil fumarate 300 mg, lamivudine 300 mg and efavirenz 400 mg as a switch strategy in virologically suppressed HIV-1-infected subjects on nonnucleoside reverse transcriptase inhibitor-containing first-line antiretroviral therapy in Pune, India

OBJECTIVES

As per National AIDS Control Organization (NACO) estimates, there are 2.1 million people living with HIV (PWH) in India, of whom 1.2 million are on first-line antiretroviral therapy (ART). This study explored the use of a single-tablet regimen containing tenofovir disoproxil fumarate 300 mg + lamivudine 300 mg + efavirenz 400 mg (TLE400 STR) as a first-line switch strategy in PWH in Pune, India.

METHODS

This retrospective cohort study was conducted in private sector ART clinics in three tertiary-level hospitals in Pune, India. PWH > 12 years of age (n = 502) who initiated first-line ART (predominantly TLE600 STR), completed ≥ 6 months of follow-up and achieved virological suppression [plasma viral load (VL) < 1000 HIV-1 RNA copies/mL] were identified and switched to TLE400 STR. The virological and immunological efficacy of TLE400 STR at 6 and 12 months of follow-up were noted. Grade 3/4 adverse events (especially efavirenz-related neuropsychiatric adverse events) leading to regimen discontinuation were also noted.

RESULTS

Of 502 PWH who switched to TLE400 STR, complete virological suppression (VL < 20 copies/mL) was maintained in more than 97% of patients at follow-up. TLE400 STR was successful in maintaining CD4 counts within the range observed at the start of the regimen. Grade 3/4 adverse events leading to TLE400 STR discontinuation were seen in 11 (2.2%) patients. Virological failure (VL > 1000 copies/mL) and treatment regimen failure were seen in six (1.2%) and 49 (9.8%) subjects, respectively.

CONCLUSIONS

TLE400 STR exhibits excellent efficacy and safety as a switch strategy and should be introduced in the Indian National ART Program, especially for PWH who are virologically suppressed on TLE600 STR.

Low-dose ritonavir-boosted darunavir in virologically suppressed HIV-1-infected adults: an open-label trial (ANRS 165 Darulight)

Objectives

To assess whether low-dose ritonavir-boosted darunavir (darunavir/r) in combination with two NRTIs could maintain virological suppression in patients on a standard regimen of darunavir/r + two NRTIs.

Design

A multicentre, Phase II, non-comparative, single-arm, open-label study.

Setting

Tertiary care hospitals in France.

Subjects

One hundred HIV-1-infected adults with no darunavir or NRTI resistance-associated mutations (RAMs) and a plasma HIV RNA level ≤50 copies/mL for ≥12 months on once-daily darunavir/r (800/100 mg) + two NRTIs for ≥6 months were switched to darunavir/r 400/100 mg with the same NRTIs.

Primary outcome measure

Proportion of patients with treatment success: plasma HIV RNA level ≤50  copies/mL up to 48 weeks without any change in the study regimen, in a modified ITT (mITT) analysis.

Results

At baseline, most patients were male (78%), with a median age of 43 years, median duration of HIV RNA ≤50 copies/mL of 35 months and median CD4 T cell count of 633 cells/mm3. Seventy-six percent received tenofovir/emtricitabine and 24% abacavir/lamivudine. Five patients were excluded from the mITT analysis. The rate of treatment success through to week 48 was 91.6% (87/95; 95% CI 84.1%-96.3%). No RAM was detected in three amplifiable genotypes. A total of 212 adverse events (AEs) occurred in 64 patients (64%); 9 AEs were serious, none leading to treatment discontinuation.

Conclusions

In HIV-infected patients well suppressed with darunavir/r (800/100 mg) and two NRTIs, a reduction of the darunavir dose to 400 mg/day maintained virological efficacy and was safe over 48 weeks.

Pharmacokinetic modelling of darunavir/ritonavir dose reduction (800/100 to 400/100 mg once daily) in a darunavir/ritonavir-containing regimen in virologically suppressed HIV-infected patients: ANRS 165 DARULIGHT sub-study

Background

In the ANRS 165 DARULIGHT study (NCT02384967) carried out in HIV-infected patients, the use of a darunavir/ritonavir-containing regimen with a switch to a reduced dose of darunavir maintained virological efficacy (≤50 copies/mL) for 48 weeks with a good safety profile.

Objectives

To assess the total and unbound blood plasma pharmacokinetics of darunavir and associated antiretrovirals, and their penetration into semen before and after dose reduction.

Patients and methods

Patients receiving a darunavir/ritonavir (800/100 mg q24h)-containing regimen for >6 months with plasma HIV-RNA ≤50 copies/mL for >12 months were switched to 400/100 mg darunavir/ritonavir q24h at week 0. A 24 h intensive pharmacokinetic blood sampling and a trough seminal sampling were performed before (week 0) and after (week 12) dose reduction. Individual pharmacokinetic parameter estimates were obtained using non-linear mixed-effect modelling for darunavir/ritonavir in blood plasma and used to test for bioequivalence, whereas darunavir/ritonavir in seminal plasma and NRTIs were analysed using a non-compartmental approach.

Results and conclusions

Fifteen patients completed the intensive pharmacokinetic analysis. There was no significant decrease in total and unbound darunavir blood plasma exposure despite a 50% decrease in darunavir daily dose from 800 to 400 mg (AUC0-24 = 65 563 versus 52 518 ng·h/mL; P = 0.25). A decrease in apparent oral clearance (CL/F) of both darunavir and ritonavir at week 12 suggests a modification of the initial darunavir/ritonavir daily dose balance (800/100 to 400/100 mg), in favour of a reduced inducer effect of darunavir on cytochrome P450 and efflux transporters compared with the standard dose.

Development of darunavir over the entire spectrum of HIV infection

Darunavir is the gold standard protease inhibitor in antiretroviral treatment. It has undergone complete development through randomised clinical trials throughout the entire spectrum of HIV infection, with 2 different dosages and clear indications of when to use each one of them. It has been studied in mono, dual and triple therapy. It can also be administered boosted with either ritonavir or cobicistat. The data indicate that it is the antiretroviral with the greatest barrier against resistance development and that it is the drug with the longest residence time bound to its receptor (protease), thus having the longest dissociation time. Its limited impact on selected mutations in the protease by other inhibitors and its high barrier against resistance have resulted in its widespread commercial use being associated with a steady decrease in the mutations circulating in the protease having an impact on its activity. Supplement information: This article is part of a supplement entitled "Co-formulated cobicistat-boosted darunavir, emtricitabine, and tenofovir alafenamide for the treatment of HIV infection", which is sponsored by Janssen.

Darunavir/ritonavir monotherapy at a low dose (600/100 mg/day) in HIV-1-infected individuals with suppressed HIV viraemia

Background

Darunavir/ritonavir is a potent PI with a high genetic barrier and pharmacological robustness favourably investigated as monotherapy. Whether darunavir could be dose reduced in the context of monotherapy deserves investigation.

Methods

Patients with HIV suppressed viraemia (plasma viral load <50 copies/mL for 12 months) under ART who had switched to darunavir/ritonavir monotherapy at 600/100 mg/day between 2013 and 2015 were included in this observational 48 week single-centre study. The primary outcome was the proportion of patients with virological success (defined as plasma viral load <50 copies/mL) at week 24. Secondary outcomes included treatment strategy success and resistance.

Results

Thirty-one patients were included with the following baseline characteristics [median (IQR)]: age 52 years (47-57), CD4+ 649 cells/mm3 (463-813), ART duration 16.3 years (9.2-22.3), nadir CD4+ 195 cells/mm3 (144-261) and duration of HIV suppression 7.8 years (4.8-9.7). Prior to switch, ART consisted of PI monotherapy for 28 of 31 patients [darunavir/ritonavir 800/100 mg/day (n = 26), lopinavir/ritonavir (n = 1) and atazanavir/ritonavir (n = 1)] and a triple drug regimen for 3 of 31 patients. Within the 48 weeks of follow-up, no virological failure occurred and two patients discontinued 600/100 mg of darunavir/ritonavir due to side effects at week 16 and 40, leading to a virological suppression rate of 100% (95% CI = 89-100) at weeks 24 and 48. Strategy success rates were 96.8% (95% CI = 83.3-99.9) at week 24 and 93.5% (95% CI = 78.6-99.2) at week 48. Median (IQR) Ctrough values of 800/100 mg of darunavir/ritonavir and 600/100 mg of darunavir/ritonavir were 1537 ng/mL (1286-1724) and 1255 ng/mL (873-2161), respectively.

Conclusions

A lower dose of darunavir/ritonavir used as monotherapy (600/100 mg/day) was highly effective in virologically suppressed HIV-infected patients. Further studies are needed to confirm these data.

Efficacy of single-tablet darunavir, cobicistat, emtricitabine, and tenofovir alafenamide in the treatment of HIV-1

INTRODUCTION

HIV eradication is not feasible and lifelong treatment is warranted to manage HIV infection. In this scenario, the advent of single-tablet, once-daily, fixed-dose co-formulations is important for reducing pill burden and maximize long-term drug adherence. Cobicistat-boosted darunavir along with emtricitabine and tenofovir alafenamide co-formulation (DRV/c/FTC/TAF or the trade name Symtuza®) is the first marketed protease inhibitor-based fixed-dose combination regimen for the treatment of HIV infection. It was approved in late 2017 by the European Medical Agency both for naïve patients and treatment-experienced patients with viral suppression. Areas covered: PubMed, ClinicalTrials.gov and presentations at scientific meetings were searched with the terms 'darunavir/cobicistat' and 'tenofovir alafenamide and emtricitabine' for clinical trials either conducted to date or ongoing as well as a review of abstracts from major HIV/AIDS and infectious diseases conferences from 2015 to up to date. Expert opinion: DRV/c/FTC/TAF is a novel unique antiretroviral drug co-formulation that exhibits a convenient dosing, satisfactory safety profile, and high antiviral efficacy, even in patients harboring viruses with resistance to antivirals other than darunavir in the short-midterm. It represents the first fixed-dose combination therapy including a protease inhibitor given as one single pill once daily for drug-naïve patients and as second-line antiretroviral therapy.

Efficacy and safety of boosted darunavir-based antiretroviral therapy in HIV-1-positive patients: results from a meta-analysis of clinical trials

Darunavir/ritonavir (DRV/r) is a second-generation protease inhibitor used in treatment-naïve and -experienced HIV-positive adult patients. To evaluate efficacy and safety in these patient settings, we performed a meta-analysis of randomized controlled trials. We considered eight studies involving 4240 antiretroviral treatment (ART)-naïve patients and 14 studies involving 2684 ART-experienced patients. Regarding efficacy in the ART-naive patients, the virological response rate was not significantly different between DRV/r and the comparator. For the ART-experienced failing patients, the virological response rate was significantly higher with DRV/r than with the comparator (RR 1.45, 95% CI: 1.01-2.08); conversely, no significant differences were found between the treatment-experienced and virologically controlled DRV/r and comparator groups. Regarding safety, the discontinuation rates due to adverse events (AEs) and DRV/r-related serious adverse events (SAEs) did not significantly differ from the rates in the comparator group (RR 0.84, 95% CI: 0.59-1.19 and RR 0.78, 95% CI: 0.57-1.05, respectively). Our meta-analysis indicated that DRV/r-based regimens were effective and tolerable for both types of patients, which was consistent with published data.

Use of a physiologically based pharmacokinetic model to simulate drug-drug interactions between antineoplastic and antiretroviral drugs

Background

Co-administration of antineoplastics with ART is challenging due to potential drug-drug interactions (DDIs). However, trials specifically assessing such DDIs are lacking. Our objective was to simulate DDIs between the antineoplastics erlotinib and gefitinib with key antiretroviral drugs and to predict dose adjustments using a physiologically based pharmacokinetic (PBPK) model.

Methods

In vitro data describing chemical properties and pharmacokinetic processes of each drug and their effect on cytochrome P450 isoforms were obtained from the literature. Plasma drug-concentration profiles were simulated in a virtual population of 50 individuals receiving erlotinib or gefitinib alone or with darunavir/ritonavir, efavirenz or etravirine. Simulated pharmacokinetic parameters and the magnitude of DDIs with probe drugs (midazolam, maraviroc) were compared with literature values. Erlotinib and gefitinib pharmacokinetics with and without antiretrovirals were compared and dose-adjustment strategies were evaluated.

Results

Simulated parameters of each drug and the magnitude of DDIs with probe drugs were in agreement with reference values. Darunavir/ritonavir increased erlotinib and gefitinib exposure, while efavirenz and etravirine decreased erlotinib and gefitinib concentrations. Based on our predictions, dose-adjustment strategies may consist of once-daily dosing erlotinib at 25 mg and gefitinib at 125 mg with darunavir/ritonavir; or erlotinib at 200 mg and gefitinib at 375 mg with etravirine. The interaction with efavirenz was not overcome even after doubling erlotinib or gefitinib doses.

Conclusions

PBPK models predicted the in vivo pharmacokinetics of erlotinib, gefitinib and the antiretrovirals darunavir/ritonavir, efavirenz and etravirine, and the DDIs between them. The simulated dose-adjustments may represent valuable strategies to optimize antineoplastic therapy in HIV-infected patients.

TURQUOISE-I Part 1b: Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir with Ribavirin for Hepatitis C Virus Infection in HIV-1 Coinfected Patients on Darunavir

Background

Ombitasvir/paritaprevir/ritonavir with dasabuvir (OBV/PTV/r + DSV) ± ribavirin (RBV) is approved for hepatitis C virus (HCV) genotype 1 (GT1) treatment in HIV-1 coinfected patients. In healthy controls, coadministration of OBV/PTV/r + DSV + darunavir (DRV) lowered DRV trough concentration (Ctrough) levels. To assess the clinical significance of this change, TURQUOISE-I, Part 1b, evaluated the efficacy and safety of OBV/PTV/r + DSV + RBV in coinfected patients on stable, DRV-containing antiretroviral therapy (ART).

Methods

Patients were HCV treatment-naive or interferon-experienced, had CD4+ lymphocyte count ≥200 cells/µL or ≥14%, and plasma HIV-1 RNA suppression on once-daily (QD) DRV-containing ART at screening. Patients were randomized to maintain DRV 800 mg QD or switch to twice-daily (BID) DRV 600 mg; all received OBV/PTV/r + DSV + RBV for 12 weeks.

Results

Twenty-two patients were enrolled and achieved SVR12. No adverse events led to discontinuation. Coadministration had minimal impact on DRV maximum observed plasma concentration and area under the curve; DRV Ctrough levels were slightly lower with DRV QD and BID. No patient experienced plasma HIV-1 RNA >200 copies/mL during treatment.

Conclusions

HCV GT1/HIV-1 coinfected patients on stable DRV-containing ART achieved 100% SVR12 while maintaining plasma HIV-1 RNA suppression. Despite DRV exposure changes, episodes of intermittent HIV-1 viremia were infrequent.

Low-dose versus standard-dose ritonavir-boosted atazanavir in virologically suppressed Thai adults with HIV (LASA): a randomised, open-label, non-inferiority trial

BACKGROUND

Thai patients with HIV have higher exposure to HIV protease inhibitors than do white people and dose reduction might be possible. We compared the efficacy of low-dose with standard-dose ritonavir-boosted atazanavir in virologically suppressed Thai patients with HIV.

METHODS

In this randomised, open-label, non-inferiority trial, we recruited patients aged 18 years or older who were receiving ritonavir-boosted protease-inhibitor-based antiretroviral therapy (ART) with HIV plasma viral loads of less than 50 copies per mL, an alanine aminotransferase concentration of less than 200 IU/L, and a creatinine clearance of at least 60 mL/min from 14 hospitals in Thailand. We excluded patients who had active AIDS-defining disease or opportunistic infections, had a history of an HIV viral load of 1000 copies per mL or more after 24 weeks of any ritonavir-boosted protease-inhibitor-based ART, used concomitant medications that could interact with the study drugs, were pregnant or lactating, had illnesses that might change the effect of the study drugs, or had a history of sensitivity to the study drugs. A biostatistician at the study coordinating centre randomly allocated patients (1:1) to switch the protease inhibitor for oral atazanavir 200 mg and ritonavir 100 mg or for atazanavir 300 mg and ritonavir 100 mg once daily, both with two nucleoside or nucleotide reverse transcriptase inhibitors at recommended doses. Randomisation was done with a minimisation schedule, stratified by recruiting centre, use of tenofovir, and use of indinavir as a component of the preswitch regimen. The primary endpoint was the proportion of patients with viral loads of less than 200 copies per mL at week 48, and we followed up patients every 12 weeks. Treatments were open label, the non-inferiority margin was -10%, and all patients who received at least one dose of study medication were analysed. This trial is registered with ClinicalTrials.gov, number NCT01159223.

FINDINGS

Between July 6, 2011, and Dec 23, 2013, we randomly assigned 559 patients: 279 to receive atazanavir 200 mg and ritonavir 100 mg (low dose) and 280 to atazanavir 300 mg and ritonavir 100 mg (standard dose). At week 48, 265 (97·1%) of 273 in the low-dose group and 267 (96·4%) of 277 in the standard-dose group had viral loads of less than 200 copies per mL (difference 0·68; 95% CI -2·29 to 3·65). Seven (3%) of 273 in the low-dose group and 21 (8%) of 277 in the standard-dose group discontinued their assigned treatment (p=0·01). 46 (17%) of 273 participants in the low-dose group and 97 (35%) of 277 in the standard-dose group had total bilirubin grade 3 or higher toxicity (≥3·12 mg/dL; p<0·0001).

INTERPRETATION

A switch to low-dose atazanavir should be recommended for Thai patients with well controlled HIV viraemia while on regimens based on boosted protease inhibitors.

FUNDING

The National Health Security Office and Kirby Institute for Infection and Immunity in Society.

Evaluation of Drug-Drug Interactions Between Hepatitis C Antiviral Agents Ombitasvir, Paritaprevir/Ritonavir, and Dasabuvir and HIV-1 Protease Inhibitors

BACKGROUND

Guidelines for the treatment of human immunodeficiency virus (HIV) infection consistently recommend initiation of antiretroviral therapy in patients with hepatitis C virus (HCV)/HIV-1 coinfection. Therefore, potential drug interactions between antiretroviral drugs and HCV direct-acting antiviral agents (DAAs) must be carefully considered. The objective of this investigation was to evaluate the compatibility of a novel combination of DAAs (the 3D regimen) with commonly prescribed HIV-1 protease inhibitors (PIs).

METHODS

Five phase 1, multiple-dose, open-label pharmacokinetic studies were performed in 144 healthy volunteers. Participants in each study were randomly assigned 1:1 into cohorts assessing the effects of the steady-state 3D regimen on steady-state HIV-1 PIs or vice versa. The 3D regimen comprised ombitasvir (25 mg once daily), paritaprevir/ritonavir (150/100 mg once daily), and dasabuvir (250 or 400 mg twice daily). The HIV-1 PIs assessed included atazanavir, darunavir, and lopinavir (administered with ritonavir). Safety, tolerability, and pharmacokinetic parameters were assessed to evaluate the compatibility of the drug regimens.

RESULTS

Coadministration of the 3D regimen with the evaluated HIV-1 PIs was generally well tolerated in healthy volunteers. Morning administration of atazanavir (300 mg once daily) and darunavir regimens exhibited no clinically meaningful drug interactions with the 3D regimen. However, owing to higher paritaprevir and/or ritonavir exposures, evening administration of atazanavir (300 mg) plus ritonavir (100 mg) or lopinavir/ritonavir (800/200 mg) with the 3D regimen is not recommended.

CONCLUSIONS

The 3D regimen can be coadministered with morning atazanavir and darunavir regimens. However, evening atazanavir plus ritonavir and lopinavir/ritonavir regimens are not recommended in combination with the 3D regimen.

Antiviral activity and CSF concentrations of 600/100 mg of darunavir/ritonavir once daily in HIV-1 patients with plasma viral suppression

OBJECTIVES

The objective of this study was to assess whether a lower dose than the currently used one of darunavir/ritonavir might achieve good CSF concentrations and contribute to inhibition of CNS viral replication.

PATIENTS AND METHODS

This was a substudy of a randomized, open, multicentre study (eudraCT 2011-006272-39), comparing the efficacy and safety of 800/100 mg of darunavir/ritonavir (darunavir 800) versus 600/100 mg of darunavir/ritonavir (darunavir 600) once daily plus tenofovir/emtricitabine or abacavir/lamivudine in 100 virologically suppressed patients. Paired blood and CSF samples were obtained. Total plasma darunavir concentrations were determined by HPLC, and CSF concentrations by liquid chromatography-tandem MS. Viral load (VL) was determined in plasma and CSF (limit of detection = 40 copies/mL) by PCR.

RESULTS

Sixteen patients were enrolled. The median (range) of darunavir CSF concentrations in darunavir 600 (n = 8) and darunavir 800 (n = 8) patients was 17.08 (5.79-30.19) and 13.23 (3.47-32.98) ng/mL, respectively (P = 0.916). The median (range) darunavir CSF:plasma ratio was 0.010 (0.005-0.022) in darunavir 600 patients and 0.008 (0.004-0.017) in the darunavir 800 arm (P = 0.370). All 16 patients had a VL < 40 copies/mL in plasma and 14 had a VL < 40 copies/mL in CSF. Of the two patients with detectable CSF VL (280 copies/mL and 159 copies/mL), one was receiving darunavir 600 and the other darunavir 800 plus tenofovir/emtricitabine. Of note, these patients had the lowest CSF darunavir concentrations in their respective groups: 5.79 ng/mL (802 ng/mL in plasma) and 3.47 ng/mL (958 ng/mL in plasma).

CONCLUSIONS

Darunavir CSF and plasma concentrations were comparable between the two arms. However, one patient from each group (with the lowest CSF darunavir concentrations in their respective groups) had detectable CSF VL despite undetectable plasma VL.

Efficacy of a reduced dose of DARUNAVIR/RTV in a cohort of antiretroviral-naïve and experienced HIV-infected patients: a medium-term follow-up

BACKGROUND

The currently approved dose of darunavir/ritonavir is 800/100 mg once daily for PI-naïve patients, and 600/100 mg twice daily for PI-pretreated patients. However, in DRV-sensitive patients at baseline in the POWER 1/2 trials, similar rates of HIV RNA suppression (1 log reduction) were achieved with doses ranging from 400/100 mg once daily to 600/100 mg twice daily. In previously virologically suppressed patients, a reduced dose of DRV (600/100 QD) is non-inferior to the standard dose (800 mg QD)1 and DRV concentrations in plasma and CSF are similar in patients receiving the above different doses (1, 2).

METHODS

Twelve treatment-naïve patients were started on darunavir/ritonavir 600/100mg once daily, with TDF/FTC (8) or ABC/3TC (4). Seven patients were switched to darunavir/ritonavir 600/100 mg once daily, with TDF/FTC (2), ABC/3TC (2), NVP (1), AZT/3TC (1). One was on monotherapy with DRV. Seven treatment-experienced patients were switched to darunavir/ritonavir 600/100 mg once daily, with TDF/FTC (5), ABC/3TC (1), RAL (1).

RESULTS

Of the 12 naïve patients (mean baseline HIV RNA 134,024 log10 copies/mL, range 4,256-397,932), 11 had HIV RNA <20 c/mL after a mean 27.4 months of follow-up (range 12-33). Mean PK level was 2,920 ng/mL (1,268-4,562). One patient had virological failure after 14 months (HIV RNA 39,300 copies/mL); no mutations were detected and after introduction of DRV/r 600 mg b.i.d., he returned aviremic. All switched patients maintained HIV RNA suppression (<20 c/mL) for a mean of 32.8 months (range 21-54). PK level was available for one patient only (Ctrough 3,442 ng/mL). Of the treatment-experienced patients (mean baseline HIV RNA 24,167 log10 copies/mL, range 112-111,426), five maintained HIV RNA suppression for a mean of 46.2 months (range 31-67). One patient interrupted HAART for three months and then restarted it, the latest HIV RNA level being 628 copies/mL after five weeks of therapy. One patient failed after 42 months (HIV RNA 3,930 copies/mL); after intensification (DRV/r 600 twice daily), he returned aviremic. PK levels were available for three patients (mean 2,502 ng/mL; range 844-4,518).

CONCLUSIONS

In this pilot study of 26 patients, use of DRV/r at 600/100 mg OD dose led to sustained HIV RNA suppression in 23 patients with acceptable PK exposures to DRV. Large non-inferiority trials are warranted to establish its efficacy.