Long-Term Durability of Tenofovir-Based Antiretroviral Therapy in Relation to the Co-Administration of Other Drug Classes in Routine Clinical Practice

Switching from tenofovir disoproxil fumarate to tenofovir alafenamide or dual therapy-based regimens in HIV-infected individuals with viral load ≤50 copies/mL: does estimated glomerular filtration rate matter?

Our aim was to evaluate the association between recent eGFR values and risk of switching from TDF to TAF or dual therapy (DT) in real life. HIV-positive patients achieving HIV-RNA ≤50 copies/mL for the first time after starting a TDF-based regimen were included. Kaplan-Meier (KM) curves and Cox regression models were used to estimate the time from TDF to switch to TAF or DT. 1486 participants were included: median (IQR) age 36 (30-42) years; baseline CKD-EPI eGFR 99.92 (86.47-111.4) mL/min/1.73m². We observed a consistently higher proportion of people with HIV-RNA ≤50 copies/mL who switched from TDF to TAF rather than to DT. By competing risk analysis, at 2 years from baseline, the probability of switching was 3.5% (95% CI 2.6-4.7%) to DT and 46.7% (42.8-48.5%) to TAF. A significantly higher probability of switching to TAF was found for patients receiving INSTI at baseline versus NNRTIs and PI/b [KM, 65.6% (61.7-69.4%) vs. 4.0% (1.8-6.1%) and 59.9% (52.7-67.2%), respectively; P < 0.0001]. eGFR <60 mL/min/1.73m² both as time-fixed covariate at baseline or as current value was associated with a higher risk of switching to DT [aHR 6.68 (2.69-16.60) and 8.18 (3.54-18.90); P < 0.001] but not to TAF-based cART [aHR 0.94 (0.39-2.31), P = 0.897; and 1.19 (0.60-2.38), P = 0.617]. Counter to our original hypothesis, current eGFR is used by clinicians to guide switches to DT but does not appear to be a key determinant for switching to TAF.

Tenofovir disoproxil fumarate discontinuation for renal outcomes: any room for treatment personalization?

Tenofovir disoproxil fumarate (TDF) is a very effective antiviral drug that has been associated with tubular dysfunction. The aim of this study was to analyze the demographic, pharmacokinetic, and pharmacogenetic variables associated with TDF discontinuation for renal outcomes in stable HIV-positive patients using multivariable analyses. Three hundred and four patients were included (73% male, with median age and eCrCl of 45.3 years and 90.9 mL/min, respectively). After a median follow-up of 28.3 months, 27 patients discontinued TDF for renal adverse events [persistent urinary abnormalities (n = 21) or eCrCl < 60 mL/min (n = 6)] providing an incidence of 3.77 events per 100 patient-year. The probability of TDF discontinuation was higher with several features (male gender, older age, not Caucasians ancestry, absence of intravenous drug abuse, protease inhibitors, previous indinavir, HCV-positivity, lower CD4 cell count, detectable HIV-RNA, lower eCrCl, spot-urine proteinuria) and higher tenofovir concentrations but not genetic variants. Tenofovir plasma concentrations were prognostic of TDF discontinuation for renal adverse events suggesting that dose-adjustment may be warranted for long-term safety.

Routine data underestimates the incidence of first-line antiretroviral drug discontinuations due to adverse drug reactions: Observational study in two South African cohorts

INTRODUCTION

Estimating the incidence of antiretroviral discontinuations due to adverse drug reactions (ADRs) is important to inform antiretroviral treatment (ART) regimen recommendations, and to guide prescribing and monitoring policies. Routinely collected clinical data is a useful source of pharmacovigilance data. We estimated the incidences of first-line antiretroviral discontinuations due to ADRs using routine clinical data, and compared them with incidences estimated using data enhanced by folder review, in two South African cohorts.

METHODS

We included patients 16 years and older on first-line ART. We selected a stratified random sample of 25% for checking of ART prescription data and reasons for antiretroviral discontinuations retrospectively, including folders reviews where required (enhanced-data sample). We estimated the incidence of antiretroviral discontinuations using Kaplan-Meier and competing risk analyses.

RESULTS

In 15396 patients, 40% had a first-line antiretroviral discontinuation by three years on ART. We could determine the reason for 65% of discontinuations using routine data only, and 84% of discontinuations, in the enhanced-data sample of 3837 patients. ADR was the most common reason for discontinuations. In the enhanced-data sample, the cumulative incidence of discontinuations due to ADRs by three years was 30.4% (95% CI: 24.4-36.6) for stavudine; 2.0% (95% CI: 1.5-2.6) for tenofovir, and 1.3% (95% CI: 0.8-2.1) for efavirenz. Using routine data only, the cumulative incidences of discontinuations due to ADRs by three years for stavudine, tenofovir, and efavirenz respectively were 23.9% (95% CI: 20.3-27.7), 1.2% (95% CI: 0.9-1.4) and 0.5% (95% CI: 0.3-0.7).

CONCLUSIONS

Although the relative rankings were similar using routine or enhanced data, lack of checking for missing reasons for discontinuation resulted in underestimates of the incidence of antiretroviral discontinuations due to ADRs. Systems to improve data collection of reasons for regimen changes prospectively would increase the capacity of routine data to answer pharmacovigilance questions.

Effect of Cobicistat on Tenofovir Disoproxil Fumarate (TDF): What Is True for TAF May Also Be True for TDF

BACKGROUND

The dose of tenofovir alafenamide is reduced from 25 to 10 mg daily when given with boosting agents. However, such dose reduction has never been adopted for tenofovir disoproxil fumarate (TDF). In this study, we aim to quantify the effect of cobicistat (COBI) both on tenofovir concentrations and TDF durability in real life setting.

METHODS

HIV-positive patients receiving TDF-containing antiretroviral therapies with at least 1 assessment of tenofovir plasma trough concentrations were included in the study. Univariate and multivariate regression analyses were performed considering tenofovir concentration as the dependent variable and clinical characteristics as independent covariates. Subsequently, survival and Cox analyses were performed considering as the primary outcome TDF discontinuation for any reasons.

RESULTS

Patients were given TDF with protease inhibitors/ritonavir (n = 212), non-nucleoside reverse transcriptase inhibitors (n = 176), integrase inhibitors (dolutegravir or raltegravir, n = 46), or with elvitegravir/COBI (ELV/COBI) (n = 76). By multivariate analysis, concomitant antiretroviral therapies resulted significantly associated with tenofovir levels, with the highest drug concentrations measured in patients given ELV/COBI. By survival analysis, we found that patients given TDF with ELV/COBI had the lowest rate of drug durability. Overall, these patients had a 2.3-fold increased risk to experience TDF discontinuation.

CONCLUSIONS

Coadministration with COBI resulted in significantly higher tenofovir concentrations and higher TDF discontinuation compared with other antiretroviral regimens. Accordingly, the possibility that the lack of proper dose adjustment for TDF when given with COBI might have biased the safety comparisons with tenofovir alafenamide during registrative trials cannot be ruled out.