Pharmacogenetics of tenofovir drug transporters in the context of HBV: Is there an impact?

BACKGROUND: Current treatments for chronic hepatitis B management include orally administered nucleos(t)ide analogues, such as tenofovir (TDF), which is an acyclic adenine nucleotide analogue used both in HBV and human immune deficiency virus (HIV). The course of HBV infection is mainly dependent on viral factors, such as HBV genotypes, immunological features and host genetic variables, but a few data are available in the context of HBV, in particular for polymorphisms of genes encoding proteins involved in drug metabolism and elimination. Consequently, the aim of this study was to evaluate the potential impact of genetic variants on TDF plasma and urine concentrations in patients with HBV, considering the role of HBV genotypes. METHODS: A retrospective cohort study at the Infectious Disease Unit of Amedeo di Savoia Hospital, Torino, Italy, was performed. Pharmacokinetic analyses were performed through liquidi chromatography, whereas pharmacogenetic analyses through real-time PCR. FINDINGS: Sixty - eight patients were analyzed: ABCC4 4976 C>T genetic variant showed an impact on urine TDF drug concentrations (p = 0.014). In addition, SLC22A6 453 AA was retained in the final regression multivariate model considering factors predicting plasma concentrations, while ABCC4 4976 TC/CC was the only predictor of urine concentrations in the univariate model. INTERPRETATION: In conclusion, this is the first study showing a potential impact of genetic variants on TDF plasma and urine concentrations in the HBV context, but further studies in different and larger cohorts of patients are required.

Data on compounding lopinavir and ritonavir suspension for non-cooperative COVID-19 patients.

The COVID-19 outbreak is now one of the most critical crises to manage for most of national healthcare systems in the world. The situation is complicated by the absence of vaccines and authorized pharmacological treatments, except for remdesivir. In this context, many medicaments, including different Ebola and HIV antivirals, are used off-label in the hospital wards as life-treating medicines for COVID-19 patients. Authorized medicaments manipulation is sometimes necessary because they are not always formulated to be administered to non-cooperative patients or they are in shortage. It is this the case of the fixed combination of lopinavir/ritonavir, which was extensively used in the first phase of the outbreak inducing a shortage of the oral solution available in the EU market. This work provides data on size distribution, osmolarity other than drug chemical stability of a lopinavir/ritonavir extemporaneous preparation made by using the solid dosage form (i.e., tablet) available on the market as drug source. The reported data indicate that such preparation is suitable to be delivered through a nasogastric tube, and enough stable for two weeks from the preparation at room temperature.

Data on the stability of darunavir/cobicistat suspension after tablet manipulation.

The COVID-19 outbreak is now one of the most critical crises to manage for most of the national healthcare systems in the world. In the absence of authorised pharmacological treatments, many antiretrovirals, including darunavir/cobicistat fixed combination, are used off-label in the hospital wards as life-treating medicines for COVID-19 patients. Unfortunately, for most of them, the drug products available on the market are not designed to be administered by a nasogastric tube to inpatients of intensive care units. Therefore, their manipulation, even if it can strongly affect the product quality, is necessary for the preparation of suspension to meet patients' need. In this situation, it is urgent to provide data and guidance to support hospital pharmacists and clinicians in their activity. The data in this article indicate that darunavir/cobicistat suspensions compounded by pharmacists using as active ingredient a commercially available tablet can be stable at least for one week.

Antiretroviral concentrations in the presence and absence of valproic acid.

OBJECTIVES: An unexpected drug-drug interaction has been recently reported between dolutegravir, an HIV integrase inhibitor, and valproic acid. Despite there being several potential underlying mechanisms, plasma protein displacement has been suggested. The aim of this study was to assess plasma concentrations of several antiretrovirals when administered with or without valproic acid. METHODS: We performed a therapeutic drug monitoring registry analysis and identified patients concomitantly taking antiretrovirals and valproic acid and without clinical affecting conditions or interacting drugs. RESULTS: One hundred and thirty-four patients were identified. Median (IQR) age and BMI were 49.7 years (45-56) and 23.4 kg/m2 (20.8-26.3) and 78 were male (58.2%). Despite small groups, we observed no major effect on antiretroviral exposure, even when considering highly protein-bound compounds (such as etravirine), with the exception of dolutegravir trough concentrations [median (IQR) = 132 ng/mL (62-227) in individuals on valproic acid versus 760 ng/mL (333-1407) in those not receiving valproic acid]. CONCLUSIONS: Valproic acid does not have a major effect on antiretrovirals other than dolutegravir. The mechanism of this unexpected drug-drug interaction may be the combination of protein displacement, reduced absorption and CYP3A4 induction.

Serum Trimethylamine-N-oxide Concentrations in People Living with HIV and the Effect of Probiotic Supplementation.

BACKGROUND: The incidence of cardiovascular disorders in people living with HIV (PLWH) is higher than that in non-infected individuals. Traditional and specific risk factors have been described but the role of the gut microbiota-dependent choline metabolite, trimethylamine-N-oxide (TMAO) is still unclear. METHODS: A cross-sectional analysis and a longitudinal analysis (with high-dose probiotic supplementation) were performed to measure serum TMAO concentrations through UHPLC-MS/MS. Stable outpatients living with HIV on highly active antiretroviral treatment with no major cardiovascular disease were enrolled. Non-parametric tests (bivariate and paired tests) and a multivariate linear regression analysis were used. RESULTS: A total of 175 participants were enrolled in the study. Median serum TMAO concentrations were 165 (103-273) ng/mL. An association with age, serum creatinine, number of antiretrovirals, multimorbidity and polypharmacy was observed; at linear logistic regression analysis, multimorbidity was the only independent predictor of TMAO concentrations. Carotid intima media thickness (IMT) was 0.85 (0.71-1.21) mm, with a trend towards higher TMAO concentrations observed in patients with IMT >0.9 mm (P=0.087). In the 25 participants who received probiotic supplementation, TMAO levels did not significantly change after 24 weeks (Wilcoxon paired P=0.220). CONCLUSION: Serum TMAO levels in PLWH were associated with multimorbidity, higher cardiovascular risk and subclinical atherosclerosis and were not affected by 6 months of high-dose probiotic supplementation.

Virological Failure in HIV to Triple Therapy With Dolutegravir-Based Firstline Treatment: Rare but Possible.

We describe a case of virological failure during initial treatment with tenofovir disoproxil fumarate/emtricitabine/dolutegravir twice daily, with concomitant rifampin treatment of staphylococcal infection, selection of R263K + E157Q, and low plasma dolutegravir levels. Using rifampin together with dolutegravir may require closer follow-up, and, if possible, plasma dolutegravir levels should be monitored.

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.

SLC22A2 variants and dolutegravir levels correlate with psychiatric symptoms in persons with HIV.

BACKGROUND: Neuropsychiatric symptoms (NPs) have been reported with dolutegravir use. We hypothesized that increasing dolutegravir trough concentrations (Ctrough) and/or polymorphism in the SLC22A2 gene, encoding the organic cation transporter-2 (OCT2), which is involved in monoamine clearance in the CNS and is inhibited by dolutegravir, might be associated with NPs. METHODS: A cross-sectional cohort of HIV-positive patients treated with a dolutegravir-containing regimen underwent determination of allelic discrimination for SLC22A2 808 C → A polymorphism and dolutegravir Ctrough. The Symptom Checklist-90-R [investigating 10 psychiatric dimensions and reporting a general severity index (GSI)], a self-reported questionnaire and the Mini-International Neuropsychiatric Interview were offered to investigate current NPs. The effects of dolutegravir Ctrough and the SLC22A2 gene variant on NPs were explored by multivariable logistic regression. RESULTS: A cohort of 203 patients was analysed: 71.4% were male, with median age 51 years and 11 years of ART exposure. Median time on dolutegravir was 18 months. Dolutegravir was associated with different antiretroviral combinations (mainly lamivudine, 38.9%, and abacavir/lamivudine, 35.5%). SLC22A2 CA genotype was independently associated with an abnormal GSI [adjusted OR (aOR) 2.43; P = 0.072], anxiety (aOR 2.61; P = 0.044), hostility (aOR 3.76; P = 0.012) and with moderate to severe headache (aOR 5.55; P = 0.037), and dolutegravir Ctrough was associated with hostility (fourth versus first quartile aOR 6.70; P = 0.007) and psychoticism (fourth versus first quartile aOR 19.01; P = 0.008). Other NPs were not associated with SLC22A2 polymorphism or dolutegravir Ctrough. CONCLUSIONS: A variant of the OCT2-encoding gene, in addition to or in synergy with higher dolutegravir Ctrough, is associated with a set of NPs observed during dolutegravir therapy.

Cerebrospinal fluid abacavir concentrations in HIV-positive patients following once-daily administration.

Abacavir is a widely used nucleotide reverse transcriptase inhibitor, for which cerebrospinal fluid (CSF) exposure has been previously assessed in twice-daily recipients. We studied abacavir CSF concentrations in 61 and nine HIV-positive patients taking abacavir once daily and twice daily, respectively. Patients on once-daily abacavir had higher plasma and CSF concentrations (96 vs. 22 ng ml-1 , P = 0.038 and 123 vs. 49 ng ml-1 , P = 0.038) but similar CSF-to-plasma ratios (0.8 vs. 0.5, P = 0.500). CSF abacavir concentrations were adequate in patients receiving once-daily treatment.

Role of CYP24A1, VDR and GC gene polymorphisms on deferasirox pharmacokinetics and clinical outcomes.

ß-Thalassemia patients develop deficiency in vitamin D absorption and liver hydroxylation, resulting in extremely low calcitriol levels. We explored the role of single-nucleotide polymorphisms (SNPs) involved in vitamin D metabolism, transport and activity on deferasirox pharmacokinetics and outcomes (effectiveness trough levels (Ctrough) and the area under the curve (AUC) cutoffs of 20 µg ml-1 and 360 µg ml-1 h-1, respectively; nonresponse AUC limit of 250 µg ml-1 h-1). Ninety-nine ß-thalassemic patients were enrolled. Drug plasma Ctrough and AUC were measured by the high-performance liquid chromatography system coupled with an ultraviolet determination method. Allelic discrimination for VDR, CYP24A1, CYP27B1 and GC gene SNPs was performed by real-time PCR. CYP24A1 22776 TT significantly influenced Cmin and negatively predicted it in regression analysis. CYP24A1 3999 CC was associated with Ctrough and Cmin and was a negative predictor of Tmax, whereas CYP24A1 8620 GG seemed to have a role in Ctrough, AUC, t1/2 and Cmin, and was an AUC negative predictor factor. Considering treatment outcome, Cdx2 and GC 1296 were retained in regression analysis as AUC efficacy cutoff negative predictors.

Efficacy of sofosbuvir and ledipasvir in an HCV+ gastro-resected patient.

WHAT IS KNOWN AND OBJECTIVE: The second-generation direct-acting antivirals represented the first major turning point for the eradication of HCV infection in almost all settings of patients. However, no data were available on use in gastro-resected patients. CASE DESCRIPTION: We report on a gastrectomized patient with chronic hepatitis C infection. She was treated with sofosbuvir and ledipasvir (SOF/LDV) for 12 weeks, with measurement of blood levels of the drugs. She obtained sustained virological response at week 12 and 24 without dose adjustment. WHAT IS NEW AND CONCLUSION: This case report can provide information useful for clinical practice in this set of patients and can open new perspectives in evaluating actual SOF/LDV bioavailability.

Treatment with direct-acting antiviral agents of hepatitis C virus infection in injecting drug users: A prospective study.

In this prospective study, we evaluated the effectiveness and tolerability of novel therapies against hepatitis C virus (HCV) in a cohort of PWID enrolled at our centre from April 2015 to July 2016. In this analysis, a total of 174 patients were included: eleven (6.3%) were treated with pegylated interferon (PEG-IFN) and ribavirin (RBV) containing regimens, 163 (93.7%) with IFN-free treatments. RBV has been used in 70 patients (40.2%); 59 (33.9%) patients were in opioid substitution therapy (OST) with methadone or buprenorphine. Overall, sustained virological response (SVR) has been observed in 162 subject (93.1%), breakthrough (BT) in three (1.7%), relapse in one (0.6%) and dropout in eight (4.6%). Treatment was interrupted for clinical conditions in seven patients: six (3.4%) had hepatic decompensation and one died for hepatocellular carcinoma (HCC). In multivariate analysis, predictive factors of treatment failure were as follows: albumin level below 3 g/dL (OR=7.190; 95% IC=1.236-41.837; P<.001), MELD score >10 (OR=5.886; 95% IC=1.411-35.994; P<.001) and years of HCV infection >20 (OR=1.286; 95% IC=0.556-9.455; P=.016). In conclusion, treatment with DAAs was effective and well tolerated in PWID; cirrhotic subjects with MELD > 10 and albumin low level showed a higher risk of developing serious adverse events and treatment failure.

Therapeutic drug monitoring of boosted PIs in HIV-positive patients: undetectable plasma concentrations and risk of virological failure.

Background: Therapeutic drug monitoring (TDM) of antiretroviral drugs is performed in selected HIV-positive patients. The aim of this study was to estimate the prevalence of undetectable plasma concentrations of ritonavir and boosted PIs and to evaluate the association between those and the 48 week risk of virological failure. Methods: A TDM registry study and a retrospective follow-up study were conducted. Plasma concentrations were measured through validated methods. According to PI and ritonavir concentrations, patients were stratified as adherent, partially non-adherent or non-adherent. Virological outcome was evaluated 48 weeks afterwards. Results: The TDM registry study included 2468 samples collected from 723 patients (68.1% male, median age 43.5 years). Eighty-seven samples (3.5%, 74 patients) and 68 samples (2.8%, 52 patients) were in the partially non-adherent and non-adherent groups, respectively; more patients on atazanavir/ritonavir (7.9%) versus darunavir/ritonavir (2% twice daily and 1.9% once daily) and lopinavir/ritonavir (1.5%; P < 0.001) were observed in the partially non-adherent group. Two hundred and ninety patients were included in the follow-up study (64.1% male, median age 40 years). Patients in the adherent group had a higher chance of viral control [81.9% (167/204)] versus the partially non-adherent group and the non-adherent group [71.7% (33/46) and 53.1% (17/32), respectively; P  =   0.001]. Based on multivariate analysis, baseline HIV RNA >50 copies/mL ( P < 0.001), genotypic susceptibility score ≤2 ( P = 0.001), lower nadir CD4 cell count ( P = 0.003) and not being in the adherent group ( P = 0.029) were independent predictors of HIV RNA >50 copies/mL at 48 weeks. Conclusions: The measurement of PI and ritonavir plasma levels can uncover incomplete compliance with treatment; TDM may represent a useful tool for identifying patients in need of adherence-promoting interventions.

Clinical pharmacology of tenofovir clearance: a pharmacokinetic/pharmacogenetic study on plasma and urines.

The HIV virus and hepatitis B virus nucleotide reverse transcriptase inhibitor tenofovir has been associated with proximal tubular toxicity; the latter was found to be predicted by plasma concentrations and with single-nucleotide polymorphisms in transporters-encoding genes. A cross-sectional analysis in adult HIV-positive patients with estimated creatinine clearance >60 ml min-1 was performed. Twelve-hour plasma and urinary tenofovir concentrations and single-nucleotide polymorphisms in several transporter-encoding genes were analysed. In 289 patients 12-h tenofovir plasma, urinary and urinary to plasma ratios were 69 ng ml-1 (interquartile range 51.5-95), 24.3 mg ml-1 (14.3-37.7) and 384 (209-560). At multivariate analysis estimated creatinine clearance, protease inhibitors co-administration and SLC28A2 CT/TT genotypes were independently associated with plasma tenofovir exposure; ABCC10 GA/AA genotypes and protease inhibitor co-administration were independently associated with the urinary to plasma tenofovir ratio. Tenofovir clearance was associated with genetic polymorphisms in host genes and with co-administered drugs: if confirmed by ongoing studies these data may inform treatment tailoring and/or dose reductions.

Successful pharmacogenetics-based optimization of unboosted atazanavir plasma exposure in HIV-positive patients: a randomized, controlled, pilot study (the REYAGEN study).

BACKGROUND: Atazanavir without ritonavir, despite efficacy and tolerability, shows low plasma concentrations that warrant optimization. METHODS: In a randomized, controlled, pilot trial, stable HIV-positive patients on atazanavir/ritonavir (with tenofovir/emtricitabine) were switched to atazanavir. In the standard-dose arm, atazanavir was administered as 400 mg once daily, while according to patients' genetics (PXR, ABCB1 and SLCO1B1), in the pharmacogenetic arm: patients with unfavourable genotypes received 200 mg of atazanavir twice daily. EudraCT number: 2009-014216-35. RESULTS: Eighty patients were enrolled with balanced baseline characteristics. The average atazanavir exposure was 253 ng/mL (150-542) in the pharmacogenetic arm versus 111 ng/mL (64-190) in the standard-dose arm (P < 0.001); 28 patients in the pharmacogenetic arm (75.7%) had atazanavir exposure >150 ng/mL versus 14 patients (38.9%) in the standard-dose arm (P = 0.001). Immunovirological and laboratory parameters had a favourable outcome throughout the study with non-significant differences between study arms. CONCLUSIONS: Atazanavir plasma exposure is higher when the schedule is chosen according to the patient's genetic profile.