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

Brief Report: Pharmacokinetics of Bictegravir and Tenofovir in Combination With Darunavir/Cobicistat in Treatment-Experienced Persons With HIV

BACKGROUND

Bictegravir coformulated with emtricitabine and tenofovir alafenamide as a fixed-dose combination (BIC/FTC/TAF 50/200/25 mg) is recommended as an initial regimen in patients who are antiretroviral (ARV)-naïve or virologically suppressed on a stable ARV regimen. However, no real-world pharmacokinetic (PK) data are available in treatment-experienced patients with antiretroviral resistance receiving BIC/FTC/TAF plus a boosted protease inhibitor.

SETTING/METHODS

This prospective, single-center, nonrandomized pharmacokinetic study enrolled adult treatment-experienced persons with HIV and creatinine clearance >30 mL/min receiving BIC/FTC/TAF + DRV/c as part of routine clinical care. Steady-state PK profiles of BIC, TAF, tenofovir (TFV), and DRV after daily dosing of BIC/FTC/TAF + darunavir/cobicistat (DRV/c) were obtained with samples at predose and 0.5, 1, 2, and 4 hours postdose. The AUC0-24 at steady state was extrapolated by imputing C0 for C24 for each participant (AUC0-tau,exp).

RESULTS

Nine participants were enrolled with a median age of 59 years (range 54-67) and median number of years on ART of 19 (range 5.8-30). The median (interquartile range [IQR]) BIC AUC0-tau,exp and Cmax values were 128.9 µg*h/mL (78.1-159.5) and 6.9 µg/mL (5.1-9.8), respectively. The median (IQR) TAF AUC0-tau,exp and Cmax values were 0.376 µg*h/mL (0.199-0.430) and 0.276 µg/mL (0.149-0.543), respectively. Predose concentrations of TFV and DRV were comparable with historical data.

CONCLUSION

Treatment-experienced persons with HIV receiving BIC/FTC/TAF + darunavir/cobicistat (DRV/c) had BIC exposures (AUC0-tau) that were increased by approximately 26% compared with historical PK data. Although TAF exposures were substantially increased, plasma TFV was only modestly higher. These results suggest that BIC/TAF/FTC + DRV/c is a viable antiviral regimen option for treatment-experienced persons.

In utero exposure to antiretroviral drugs and pregnancy outcomes: Analysis of the French ANRS pharmacovigilance database

AIMS

In 2018, 1.07 million pregnant women received antiretroviral drugs, raising whether this affects pregnancy outcomes. We assessed the adverse pregnancy outcomes associated with prenatal antiretroviral drug exposure, notified to the French ANRS pharmacovigilance system.

METHODS

An exhaustive case report series has been performed using the ANRS pharmacovigilance database. All ANRS-sponsored HIV clinical research studies using antiretroviral drugs either in pregnant women or women of childbearing age were eligible from 2004 to 2019. We analysed the following pregnancy outcomes: abortion, ectopic pregnancy, stillbirth, prematurity (<37 weeks of gestational age), low birth weight (<2500 g) and congenital abnormalities. A logistic regression was performed to assess the odds ratio (OR) for each outcome separately (if occurrence >50) compared to the outcome observed when exposed to non-nucleoside-reverse-transcriptase-inhibitor (NNRTI)-based regimen as the reference.

RESULTS

Among the 34 studies selected, 918 deliveries occurred, of whom 88% had pregnancy outcomes documented. Pregnant women were mainly exposed to PI (n = 387, 48.6%), NNRTI (n = 331, 41.5%) and INI-based combinations (n = 40, 5.0%, 18 on dolutegravir). Compared to NNRTI-based combinations, there was no significant association observed with exposure to other antiretroviral combination for spontaneous abortion, prematurity or low birth weight, except an increased risk of low birth weight in new-born exposed to exclusive nucleoside-reverse-transcriptase-inhibitor (NRTI) combinations (n = 4; OR 7.50 [1.49-37.83]).

CONCLUSIONS

Our study, mainly based on protease inhibitor (PI) and NNRTI-based regimens, is overall reassuring on the risk of adverse pregnancy outcomes, except for NRTI which should be interpreted cautiously (small number, indication bias). In this study, the number of integrase inhibitor (INI)-based combinations was too low to draw any conclusions.

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.

Individualized Protease Inhibitor Monotherapy: The Role of Pharmacokinetics and Pharmacogenetics in an Aged and Heavily Treated HIV-Infected Patient

Antiretroviral therapy has changed the history of HIV infection from a lethal disease to a chronic infection, with the emergence of long-term adverse effects. Herein we present a case of a heavily treated HIV-infected man in whom antiretroviral toxicity had been observed. The lopinavir/ritonavir plasma concentrations at standard doses were significantly above the recommended levels. Pharmacogenetic analysis revealed a polymorphism in the DRD3 gene associated with a decrease in the rate of drug metabolism. Additionally, the patient's low body mass index could have contributed to a greater degree of patient exposure to the drug. After the withdrawal of tenofovir disoproxil and the establishment of individualized protease inhibitor monotherapy at reduced doses, a decrease in the intensity of adverse events was observed, while the clinical outcomes were maintained. The pharmacokinetic-pharmacogenetic analysis was shown to be a tool of huge interest for the management and durability of antiretroviral therapy.

Low-dose ritonavir-boosted darunavir once daily versus ritonavir-boosted lopinavir for participants with less than 50 HIV RNA copies per mL (WRHI 052): a randomised, open-label, phase 3, non-inferiority trial

BACKGROUND

Pilot studies suggest that ritonavir-boosted darunavir could show high efficacy at doses below those currently approved. We investigated whether switch to 400 mg of darunavir boosted with 100 mg ritonavir once daily could show equivalent efficacy to continuation of ritonavir-boosted lopinavir (a protease inhibitor commonly used in low-income and middle-income countries) for individuals with HIV RNA suppression.

METHODS

In the WRHI 052 study, a randomised, parallel-group, open-label, non-inferiority phase 3 trial, adults who were HIV-1 positive were enrolled in Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa. Eligible participants were 18 years or older, who tolerated ritonavir-boosted lopinavir in combination with two nucleoside analogues (standard of care) for 6 months or more, and had plasma HIV-1 RNA of less than 50 copies per mL within 60 days of enrolment. We randomly assigned participants (1:1), using a computer-generated randomisation plan, to switch to darunavir (400 mg) boosted with ritonavir (100 mg) once daily or remain on ritonavir-boosted lopinavir (800 mg [plus 200 mg ritonavir]), with nucleoside analogues left unchanged. The primary endpoint was the proportion of patients with less than 50 HIV-1 RNA copies per mL at week 48 (US Food and Drug Administration snapshot algorithm; non-inferiority margin -4%). Primary and safety analyses included participants receiving at least one dose of darunavir boosted with ritonavir. This trial is registered with ClinicalTrials.gov, number NCT02671383.

FINDINGS

Between June 30, 2016, and June 15, 2017, 148 participants were assigned to ritonavir-boosted darunavir 400 mg and 152 continued on their lopinavir-containing regimen. Four (3%) patients in the darunavir group and three (2%) in the lopinavir group discontinued before week 48. At week 48, darunavir was non-inferior to lopinavir for the primary outcome (142 [96%] of 148 participants on darunavir had <50 HIV-1 RNA copies per mL vs 143 [94%] of 152 participants on lopinavir; difference 1·9% [95% CI -3·4 to 7·3]), with a predefined margin of -4%. More participants taking darunavir (30 [20%] participants) had drug-related adverse events than those on lopinavir (eight [5%]), but the adverse events were generally asymptomatic and resolved when switching back to lopinavir. Elevated liver transaminase in three (1%; one symptomatic) darunavir participants led to study withdrawal; all transaminase elevations resolved on restarting lopinavir.

INTERPRETATION

Low-dose ritonavir-boosted darunavir might be a safe and efficacious switch option to maintain HIV suppression for patients on lopinavir. However, an adequately powered and designed study in viraemic participants is needed.

FUNDING

South African Medical Research Council, United States Agency for International Development, and US National Institute of Allergy and Infectious Diseases.