Reply to: A commentary on "Safety of tenofovir alafenamide in the context of hyperlipidemia and cardiovascular diseases: a nationwide analysis".

Despite numerous small-scale studies, the correlation between tenofovir alafenamide fumarate (TAF) and hyperlipidemia remains still limited. This study aims to evaluate the safety of TAF regarding hyperlipidemia and cardiovascular diseases using a nationwide cohort. We conducted a retrospective analysis of claims data from the Health Insurance Review and Assessment Service, comparing incidence rates of hyperlipidemia and major adverse cardiovascular events (MACE) using 1:1 propensity score matching between TAF and tenofovir disoproxil fumarate (TDF) users. The incidence of hyperlipidemia among TAF users was 21.38 per 1000 person-years, compared to 10.04 among TDF users. The incidence rate ratio (IRR) was 2.13 (95% confidence interval [CI] 1.92-2.36), indicating a significantly higher incidence in TAF users compared to TDF users (p < 0.001). After adjusting for other factors, Cox regression analysis showed that TAF was significantly associated with hyperlipidemia compared to TDF (hazard ratio [HR] 1.99, 95% CI 1.79-2.20, p < 0.001). There was no significant difference in the incidence of MACE between TDF and TAF users (2.19 per 1,000 person-years for TDF and 2.25 per 1,000 person-years for TAF, IRR 1.02, 95% CI 0.79-1.33, p = 0.853), with Cox regression analysis showing no disparity between the groups (HR 1.03, 95% CI 0.78-1.36, p = 0.829). TAF is associated with a higher incidence of hyperlipidemia than TDF. While the incidence of MACE in the TAF group has not shown a significant increase compared to the TDF group, further investigation into long-term outcomes is warranted. Lipid monitoring in TAF and TDF patients is essential for managing risks and reducing cardiovascular complications.

Tenofovir alafenamide (TAF) is approved for paediatric use in fixed-dose combination tablets, but efficacy and safety data in children are limited. We conducted a systematic review on the efficacy/effectiveness and safety of TAF in infants, children and adolescents living with HIV. We searched MEDLINE, Embase, the Cochrane Library, clinical trial registries, reference lists and relevant conferences to identify literature published January 2009-March 2021. We included clinical trials and observational studies assessing the efficacy/effectiveness or safety of TAF through ≥6 months of treatment in participants aged 0-19 years. Overall 3626 abstracts and 371 full papers were screened. Four single-arm, innovator-funded trials (341 participants) and a pooled analysis of those trials were identified. All four trials included treatment-experienced and virally suppressed children or adolescents. One trial also included treatment-naïve adolescents with baseline viral load >1000 copies/ml. The risk of bias was rated as low in one study and unclear in the other three owing to missing data on study design (all conference presentations). At 48 weeks, 92% (46/50) of treatment-naïve participants were virally suppressed (one trial). Among treatment-experienced participants with viral load at 48 weeks, 214 of 224 participants were virally suppressed. Across the studies, one grade 3/4 adverse event was considered drug-related (intermediate uveitis). There were three discontinuations for adverse events (grade 2 anxiety and insomnia, grade 1 iridocyclitis [drug-related] and grade 1 pulmonary tuberculosis [unrelated to treatment]). One accidental death occurred across the four studies. In the pooled analysis of 223 participants, the median change in bone mineral density z-score (height- and age-adjusted) from baseline to 48 weeks was -0.12 (interquartile range [IQR] -0.46, 0.17) to 0.05 (IQR not reported) for spine, and -0.09 (IQR -0.33, 0.07) to 0.09 (IQR not reported) for total body less head. Weight-for-age z-scores increased by 0.25 from baseline to 48 weeks. Four single-arm trials were identified in this systematic review, with initial evidence suggesting good viral suppression and no obvious safety concerns in children and adolescents on TAF-containing regimens over 24-48 weeks. However, further comparative and longer-term safety data are needed in children and adolescents, including on weight and metabolic changes.

Tenofovir alafenamide (TAF) has shown non-inferior efficacy to tenofovir disoproxil fumarate (TDF), with superior bone and renal safety. To characterise 5-year TAF efficacy and safety in patients of East Asian ethnicity from pivotal Phase 3 studies. Patients were randomised (2:1) to receive TAF or TDF for up to 3 years of double-blind treatment, followed by open-label TAF. Patients either continued TAF or switched from TDF to TAF at Week 96 (TDF → TAF 3 years) or Week 144 (TDF → TAF 2 years) of treatment. Efficacy endpoints (virologic, biochemical and serologic) and safety were assessed. Among 591 patients of East Asian ethnicity (TAF, n = 401; TDF → TAF 3 years, n = 84; TDF → TAF 2 years, n = 106), high rates of virologic control were achieved (89%, 94% and 92%, respectively) at Year 5 (missing = failure analysis). At Year 5, rates of alanine aminotransferase normalisation (85%, 90% and 78%) and hepatitis B e antigen loss (36%, 43% and 44%) were similar. Following the switch from TDF to TAF, changes in fasting lipid parameters were consistent with removal of the known lipid-lowering effect of TDF. However, changes in the total cholesterol to high-density lipoprotein ratio (marker of cardiovascular risk) were minimal and comparable in all groups by Year 5. Renal and bone parameters improved after switching. Through 5 years, rates of virologic suppression were high in East Asian patients treated with TAF or switched from TDF to TAF. TAF and TDF were well tolerated, with improved renal and bone safety observed in patients switching from TDF to TAF.

Switching from tenofovir disoproxil fumarate to tenofovir alafenamide in virologically suppressed patients with chronic hepatitis B: a randomised, double-blind, phase 3, multicentre non-inferiority study

ABSTRACTIntroduction: Tenofovir alafenamide (TAF)-containing fixed-dose drug combinations (FDCs) are increasingly being used in managing pregnant women living with HIV. However, TAF is not currently recommended during pregnancy due to limited pharmacokinetic and safety data. TAF, a newer nucleotide phosphonamidate prodrug of tenofovir (TFV), achieves high levels of tenofovir-diphosphate in lymphoid cells and hepatocytes, and 90% lower systemic concentrations of TFV compared to tenofovir disoproxil fumarate (TDF), thereby maximizing TAF’s antiviral efficacy, potency and clinical safety.Areas covered: This review discusses the currently available information on the pharmacology of TAF in pregnant women living with HIV. Pharmacokinetic studies with TAF during pregnancy have yielded varying results compared to postpartum, but TAF exposures during pregnancy have been within the range of those typically observed in non-pregnant adults. The efficacy and safety of TAF in treatment-naïve pregnant women living with HIV is currently being evaluated in the VESTED study, a phase-III NIH randomized clinical trial.Expert opinion: Initial pregnancy data suggest that TAF-based FDCs have high efficacy and low risk of adverse effects during pregnancy. TAF is likely to become part of first-line regimens for use in pregnant women living with HIV once additional pregnancy data from phase III trials are available.

96 weeks treatment of tenofovir alafenamide vs. tenofovir disoproxil fumarate for hepatitis B virus infection

Entecavir (ETV) is a potent and safe antiviral agent for patients with chronic hepatitis B (CHB); however, some patients may exhibit suboptimal response or resistance to ETV. Tenofovir alafenamide (TAF) is a novel tenofovir prodrug with improved pharmacokinetics and reduced renal and bone toxicity compared with tenofovir disoproxil fumarate. To evaluate the efficacy and safety of switching from ETV to TAF in patients with CHB exhibiting suboptimal response to ETV. A total of 60 patients with CHB who had been treated with ETV for at least 12 mo and had persistent or recurrent viremia [Hepatitis B virus (HBV) DNA ≥ 20 IU/mL] or partial virologic response (HBV DNA < 20 IU/mL, but detectable) were enrolled in the study. The patients were randomly assigned to either continue ETV (0.5 mg) daily or switch to TAF (25 mg) daily for 48 wk. The primary endpoint was the proportion of patients who achieved a virologic response (HBV DNA level < 20 IU/mL) at week 48. Secondary endpoints included changes in serum alanine aminotransferase (ALT), hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and anti-HBe levels, and renal and bone safety parameters. At week 48, the proportion of patients who achieved a virologic response was significantly higher in the TAF group than in the ETV group (93.3% vs 66.7%, P = 0.012). The mean reduction in HBV DNA from baseline was also significantly greater in the TAF group than in the ETV group (-3.8 vs -2.4 Log10 IU/mL, P < 0.001). The rates of ALT normalization, HBeAg loss, HBeAg seroconversion, and HBsAg loss were not found to significantly differ between the two groups. None of the patients developed genotypic resistance to ETV or TAF. Both drugs were well tolerated, with no serious adverse events or discontinuations caused by adverse events. No significant changes were observed in the estimated glomerular filtration rate, serum creatinine level, or urine protein-to-creatinine ratio in either group. The TAF group had a significantly lower decrease in bone mineral density at the lumbar spine and hip than the ETV group (-0.8% vs -2.1%, P = 0.004; -0.6% vs -1.8%, P = 0.007, respectively). Switching from ETV to TAF is effective and safe for patients with CHB exhibiting a suboptimal response to ETV and may prevent further viral resistance and reduce renal and bone toxicity.

Background and AimAdministration of tenofovir alafenamide (TAF) as prevention or treatment of hepatitis B virus (HBV) reactivation is not well known. The aim of this study is to reveal the efficacy and safety of TAF against HBV reactivation.MethodsEntecavir (ETV) and TAF were given to 66 and 11 patients, respectively, as prophylaxis against or treatment of HBV reactivation during chemotherapy or immune suppression therapy from January 2010 to June 2020. The antiviral effects and safety were assessed.ResultsAt week 24, the antiviral effects on patients receiving ETV and TAF were similar in terms of reduction of HBV DNA (−2.83 ± 1.45log IU/mL vs −3.05 ± 2.47log IU/mL; P = 0.857) and achieving undetectable levels of HBV DNA (78.8 vs 90.9%; P = 0.681). There was no significant difference in the decrease in the estimated glomerular filtration rate (eGFR) between the two groups (−0.62 ± 11.2 mL/min/1.73 m2 vs −3.67 ± 13.2 mL/min/1.73 m2; P = 0.291).ConclusionTAF is safe and effective against HBV reactivation.

Background The recently updated EASL Guidelines for Management of HBV Infection (2017) recommend the use of TAF as an alternative to TDF in patients with risk factors unfavourable to TDF use. We, therefore, performed an evaluation of the efficacy and safety of TAF compared with TDF in patients considered to be at risk for adverse bone and/or renal effects from TDF. Methods In two Phase 3 studies, patients (HBeAg-positive [n=873] and HBeAg-negative [n=425]) were randomised 2:1 to TAF or TDF. Antiviral efficacy (HBV DNA 60 years, osteoporosis of hip or spine by t-score, eGFRCG 30 mg/g, or serum phosphorus Results Of 1298 patients randomised and treated in the 2 studies, 239 (18%; 151 TAF and 88 TDF) patients had at least 1 risk factor for TDF use. Baseline demographics were similar between groups. At Week 96, similar antiviral efficacy (HBV DNA Conclusions In CHB patients considered to be at risk for TDF toxicity, TAF showed significantly less impact on bone and renal parameters while efficacy was maintained in this subgroup through 96 weeks.

Proximal renal tubulopathy (PRT) is an infrequent complication of tenofovir disoproxil fumarate (TDF). It remains to be established whether tenofovir alafenamide (TAF) can be safely administered to individuals who experienced PRT on TDF. Individuals with a history of TDF-associated PRT and current estimated glomerular filtration rate (eGFR) over 30 mL/min/1.73 m2 initiated TAF and were followed for 96 weeks. The primary outcome of interest was recurrent PRT. Secondary outcomes were changes in kidney biomarkers, bone biomarkers, and bone mineral density (BMD). Data were analyzed using multilevel mixed-effects linear regression models. The trial was registered under EudraCT 2016-003345-29. All 31 participants [median age 55 (inter-quartile range 51, 60) years, 97% men, 87% White ethnicity] remained on TAF at week 96, and none developed glycosuria or recurrent PRT. Participants experienced small declines in eGFR-creatinine [-1.9 (95% confidence interval: -3.5 to -0.3) mL/min/1.73 m2/yr; P = 0.024], but not in eGFR-cystatin C [-0.9 (-2.1 to 0.4) mL/min/1.73 m2/yr; P = 0.16]. Ten (32%) and 5 (16%) participants experienced rapid (>5 mL/min/1.73 m2/yr) decline in eGFR-creatinine and eGFR-cystatin C. No significant change in other kidney biomarkers, bone turnover, or BMD was observed (P > 0.2). In individuals with a history of PRT on TDF, 96 weeks of TAF was not associated with recurrent PRT or adverse effects on renal tubular function, bone turnover, or BMD. These data suggest that TAF is a treatment option for this vulnerable population.

Currently, two-drug antiretroviral regimens are emerging fields in life-long treatment in people living with HIV. This randomized non-inferiority open-label controlled trial was designed to compare the 48-week efficacy and safety of tenofovir alafenamide plus dolutegravir versus the standard triple therapy in virologically suppressed people living with HIV. To the best of our knowledge this combination has not been studied before. This open-label randomized controlled trial was conducted in treatment-experienced people with HIV who had HIV-RNA < 47 copies/mL for at least two years. Patients received either tenofovir alafenamide plus dolutegravir combination (26 patients) or a standard three-drug regimen (29 patients). The primary outcome was the proportion of patients maintaining HIV-RNA < 47 copies/mL during 48weeks, and the secondary outcomes were CD4 cell count changes, the adherence rate, and adverse drug reactions, all over 48weeks of study. HIV viral load remained undetectable (HIV-RNA < 47 copies/mL) during the 48weeks of the study in both arms. The absolute CD4 cell count change was not significant between the two groups. The overall proportion of adverse effects in each group was comparable. The rate of adherence to treatment was acceptable in both groups, and no significant difference was observed. Treatment simplification with tenofovir alafenamide plus dolutegravir regimen as maintenance therapy was non-inferior in terms of efficacy and safety compared to the standard triple therapy. Comparing efficacy of antiretroviral therapy.

An association between hepatitis B core-related antigen (HBcrAg) kinetics and hepatocarcinogenesis during nucleoside (t)id analog (NA) treatment has recently been reported. HBcrAg kinetics and factors associated with HBcrAg response during tenofovir alafenamide (TAF) administration remain unclear. In this multicenter retrospective study, we aimed to clarify the efficacy and safety of TAF in treatment-naïve patients with chronic hepatitis B, focusing on the reduction in HBcrAg levels. Patients were treated with TAF monotherapy for 96weeks, and the kinetics of HBcrAg during treatment and the factors associated with HBcrAg response (defined as a change in HBcrAg of -1logIU/mL from baseline) were evaluated. The study population comprised 241 patients, 36.9% of whom were HBeAg-positive. The median baseline HBcrAg level was 4.7logIU/mL. The median change in HBcrAg from baseline was -1.1logIU/mL at 96weeks after treatment. The HBcrAg response rate at 96weeks was 56.6% (43/76). Multivariate analysis revealed high alanine transaminase level as an independent baseline factor associated with HBcrAg response at 96weeks of treatment (p=4.53×10-6). No correlation was found between the HBcrAg and hepatitis B surface antigen kinetics in patients treated with TAF monotherapy. In TAF monotherapy for patients with chronic hepatitis B, HBcrAg levels were significantly decreased and baseline alanine transaminase level is an important factor associated with HBcrAg reduction. As no correlation was found between HBcrAg and reduced hepatitis B surface antigen levels in this study, HBcrAg kinetics in addition to hepatitis B surface antigen may need to be monitored during TAF treatment.

ABSTRACTIntroduction: Tenofovir alafenamide (TAF) has recently been approved for chronic hepatitis B (CHB). It is more stable than tenofovir disoproxil fumarate (TDF) in the plasma and can provide similar efficacy with lower circulating concentration in patients with hepatitis B virus (HBV) infection.Areas covered: This synopsis will review the current anti-HBV standard practice and the changing epidemiology of CHB, specifically the controversies surrounding the renal and bone safety associated with TDF use in the context of an aging CHB population. We will review data from phase 3 registration trials, which demonstrated TAF was not inferior to TDF in antiviral efficacy for both HBeAg-positive and HBeAg-negative patients, while associated with less reduction in the estimated glomerular filtration rate and bone mineral density.Expert commentary: Current data supports the use of TAF as one of the first-line antiviral agents for general CHB patients without hepatic decompensation. However, more real-world data with long-term observation are needed to better define the role of TAF among other oral regimens. Additional studies are also needed to evaluate the efficacy and safety of TAF in special populations such as those with impaired hepatic function, existing impaired renal and/or bone function, and in pregnant women.

Letters on "Efficacy and Safety of Tenofovir Alafenamide (TAF) and Tenofovir Disoproxil Fumarate (TDF) Followed by TAF in Chronic Hepatitis B Patients of East Asian Ethnicity Following 5 Years of Treatment." Authors' Reply.

Background: Tenofovir alafenamide (TAF) has been effective against naïve patients with chronic hepatitis B (CHB) in phase 3 clinical trials. However, its real-world data are still limited. Objectives: This study aimed to investigate the effectiveness and safety of TAF in real-life situations in treatment-naïve (TN) and treatment-experienced (TE) CHB patients in China. Methods: This retrospective study enrolled TAF-treated patients between January 2019 and October 2020 at the outpatient clinic of West China Hospital. The primary endpoint was the rates of virologic response (VR), and the secondary endpoints were the proportion of normal alanine aminotransferase (ALT) and quantitative hepatitis B surface antigen (qHBsAg) levels. Safety endpoints comprised serum lipid profiles, changes in estimated glomerular filtration rate (eGFR), and serum creatinine (Scr). Results: A total of 161 TAF-treated patients were enrolled, including 49 TN patients and 112 TE patients. In the TN group, the VR rate at week 96 was 91.7% (22/24), and the proportion of normal ALT at week 96 was 95.8% (23/24). In the TE group, the VR rate at week 96 was 97.2% (69/71), and the proportion of normal ALT at week 96 was 90.1% (64/71). Serum qHBsAg levels decreased from 2930 to 1292 IU/mL in the TN group and 1158 to 533IU/mL in the TE group during 96 weeks of treatment (P = 0.05). For patients in the TN and TE groups, when compared to baseline measurements, serum creatinine increased (+7.91 vs. +6.62 mL/min/1.73 m2, P = 0.52) while eGFR decreased (-11.46 vs. -10.90 µmol/L, P = 0.82) at week 96. Simultaneously, triglycerides (TG) (+ 0.39 vs. + 0.31 mmol/L, P = 0.32), total cholesterol (TC) (+0.65 vs. +0.52 mmol/L, P = 0.02), and low-density lipoprotein cholesterol (LDL-C) (+0.25 vs. +0.25 mmol/L, P = 0.60) increased over time. Conclusions: TAF was highly effective in TN and TE CHB patients. However, there are potential risks in eGFR decrease and a continuous increase in lipidemia with the prolongation of medication time.