gs-7340 and Hepatitis-B

At Bristol-Myers (BM) (1985-1990), John C. Martin started his HIV career with directing the clinical development of didanosine (ddI) and stavudine (d4T). During this period, he became aware of the acyclic nucleoside phosphonates (ANPs), such as (

Topics: Alanine; Anti-HIV Agents; Drug Therapy, Combination; Emtricitabine, Tenofovir Disoproxil Fumarate Drug Combination; Hepatitis B; History, 20th Century; History, 21st Century; HIV; HIV Infections; Humans; Pre-Exposure Prophylaxis; Reverse Transcriptase Inhibitors; Tenofovir

Tenofovir (TFV) is the cornerstone of the treatment and prophylaxis of HIV infections. It has been routinely used in its prodrug form TDF (tenofovir disoproxil fumarate) combined with emtricitabine ((-)FTC) and other antiretroviral agents. TDF has now been replaced by TAF (tenofovir alafenamide) which allows better uptake by the lymphoid tissue. In combination with elvitegravir (E), cobicistat (C), emtricitabine (F), TAF can be advocated as an STR (single tablet regimen, Genvoya®) for the treatment of HIV infections. In this combination, E and C may in the future be replaced by bictegravir. The prophylaxis of HIV infection is momentarily based upon Truvada®, the combination of F with TDF, which in the future may also be replaced by TAF. TAF (Vemlidy®) has also replaced TDF (Viread®) for the treatment of hepatitis B virus (HBV) infections. Both TDF and TAF offer little or no risk for virus-drug resistance. As compared to TDF, TAF limits the risk for nephrotoxicity and loss of bone mineral density. What remains to be settled, however, before the universal use of TAF could be recommended, is its safety during pregnancy and its applicability in the treatment of tuberculosis, in combination with rifampicin.

Topics: Adenine; Alanine; Antiviral Agents; Drug Resistance, Viral; Drug Therapy, Combination; Hepatitis B; HIV Infections; Humans; Pre-Exposure Prophylaxis; Tenofovir; Treatment Outcome

The antiviral agent tenofovir is highly effective for the treatment of HIV and hepatitis B virus infections, and the older prodrug tenofovir disoproxil fumarate (TDF) is also a component of daily preexposure prophylaxis (PrEP) to reduce the risk of HIV infection in high-risk populations. Although TDF is well tolerated, the potential for kidney and bone toxicity has important implications for public health given the large number of individuals exposed to TDF worldwide. This review summarizes the recent literature on kidney and bone health in individuals treated with TDF and the newer prodrug tenofovir alafenamide (TAF).. Risk factors for TDF toxicity appear to be similar in patients treated for HIV or hepatitis B virus and in HIV-uninfected PrEP users, although drug-drug interactions are a more important concern in HIV-positive individuals. The risk of toxicity appears to be lower with TAF, but further studies are needed to confirm the safety of long-term use and to evaluate the efficacy of TAF-based PrEP.. Nephrologists should be aware of the potential kidney and bone toxicity of TDF, as well as unique situations in which the newer prodrug TAF may contribute to kidney injury.

Topics: Adenine; Alanine; Antiviral Agents; Bone Density; Drug Interactions; Glomerular Filtration Rate; Hepatitis B; HIV Infections; Humans; Kidney Diseases; Pre-Exposure Prophylaxis; Prodrugs; Tenofovir

Topics: Adenine; Alanine; Animals; Antiviral Agents; Clinical Trials as Topic; Hepatitis B; Humans; Tenofovir

It remains unknown whether tenofovir alafenamide (TAF) could replace tenofovir disoproxil fumarate (TDF) in patients with drug-resistant hepatitis B virus (HBV).. In this multicenter randomized non-inferiority trial, 174 patients with HBV resistant to multiple drugs (lamivudine, entecavir, and/or adefovir) under TDF monotherapy for ≥96 weeks were randomized 1:1 to switch to TAF (n = 87) or continue TDF (n = 87) for 48 weeks. The primary endpoint was proportion of patients with HBV DNA <60 IU/mL at week 48.. At baseline, 84 and 80 patients had HBV DNA <60 IU/mL in the TAF and TDF groups, respectively. At week 48, the proportion of patients with HBV DNA <60 IU/mL was 98.9% (86/87) in TAF group, showing non-inferiority to TDF group (97.7%, 85/87; difference, 1.1%; 95% confidence interval, -2.7% to 5.0%). Changes in median alanine aminotransferase at week 48 from baseline were statistically different between TAF and TDF groups (-3 IU/L vs +2 IU/L; P = .02). TAF group showed a statistically greater increase in bone mineral density at spine (+1.84% vs +0.08%; P = .01) and numerically higher increase in mean estimated glomerular filtration rate (+8.2% vs +4.5%; P = .06) compared with TDF group. Compared with TDF group, TAF group showed significantly greater increases in mean body weight (0.71 vs -0.37 kg; P = .01) and total, low-density lipoprotein, and high-density lipoprotein cholesterol levels (P < .001 for all) at week 48 from baseline.. TAF could be substituted for TDF in patients with multidrug-resistant HBV for improved bone and renal safety without a loss of efficacy. However, increases in body weight and cholesterol levels with TAF treatment would be a concern. ClinicalTrials.gov no.: NCT03241641.

Topics: Alanine; Antiviral Agents; Hepatitis B; Hepatitis B, Chronic; Humans; Tenofovir; Treatment Outcome

Tenofovir alafenamide (TAF) is a new prodrug of tenofovir developed to treat patients with chronic hepatitis B virus (HBV) infection at a lower dose than tenofovir disoproxil fumarate (TDF) through more efficient delivery of tenofovir to hepatocytes. In 48-week results from two ongoing, double-blind, randomized phase III trials, TAF was non-inferior to TDF in efficacy with improved renal and bone safety. We report 96-week outcomes for both trials.. In two international trials, patients with chronic HBV infection were randomized 2:1 to receive 25 mg TAF or 300 mg TDF in a double-blinded fashion. One study enrolled HBeAg-positive patients and the other HBeAg-negative patients. We assessed efficacy in each study, and safety in the pooled population.. At week 96, the differences in the rates of viral suppression were similar in HBeAg-positive patients receiving TAF and TDF (73% vs. 75%, respectively, adjusted difference -2.2% (95% CI -8.3 to 3.9%; p = 0.47), and in HBeAg-negative patients receiving TAF and TDF (90% vs. 91%, respectively, adjusted difference -0.6% (95% CI -7.0 to 5.8%; p = 0.84). In both studies the proportions of patients with alanine aminotransferase above the upper limit of normal at baseline, who had normal alanine aminotransferase at week 96 of treatment, were significantly higher in patients receiving TAF than in those receiving TDF. In the pooled safety population, patients receiving TAF had significantly smaller decreases in bone mineral density than those receiving TDF in the hip (mean % change -0.33% vs. -2.51%; p <0.001) and lumbar spine (mean % change -0.75% vs. -2.57%; p <0.001), as well as a significantly smaller median change in estimated glomerular filtration rate by Cockcroft-Gault method (-1.2 vs. -4.8 mg/dl; p <0.001).. In patients with HBV infection, TAF remained as effective as TDF, with continued improved renal and bone safety, two years after the initiation of treatment. Clinicaltrials.gov number: NCT01940471 and NCT01940341.. At week 96 of two ongoing studies comparing the efficacy and safety of tenofovir alafenamide (TAF) to tenofovir disoproxil fumarate (TDF) for the treatment of chronic hepatitis B patients, TAF continues to be as effective as TDF with continued improved renal and bone safety. Registration: Clinicaltrials.gov number: NCT01940471 and NCT01940341.

Topics: Adenine; Adolescent; Adult; Aged; Aged, 80 and over; Alanine; Alanine Transaminase; Bone Density; DNA, Viral; Double-Blind Method; Drug Resistance, Viral; Female; Glomerular Filtration Rate; Hepatitis B; Hepatitis B e Antigens; Humans; Male; Middle Aged; Tenofovir; Young Adult

Coformulated elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide (E/C/F/TAF) has high efficacy and improved renal and bone safety in multiple phase 3 trials; TAF single agent is being studied in 2 phase 3 trials in patients with chronic hepatitis B. We report the results of an open-label, noncomparative switch study evaluating the efficacy and safety of E/C/F/TAF in HIV/hepatitis B virus (HBV)-coinfected adults. At 48 weeks, 91.7% of the 72 participants maintained or achieved virologic suppression (HIV-1 RNA <50 copies/mL; HBV DNA <29 IU/mL). Seroconversion occurred in 2.9% of hepatitis B surface antigen-positive participants and in 3.3% of HBV e antigen-positive participants; 40% of those with abnormal alanine aminotransferase normalized. E/C/F/TAF was associated with improved renal function and reduced bone turnover. These data support the use of E/C/F/TAF in treating HIV/HBV coinfection.

Topics: Adenine; Alanine; Anti-HIV Agents; Cobicistat; Coinfection; Drug Combinations; Drug Substitution; Emtricitabine; Female; Hepatitis B; HIV Infections; Humans; Male; Middle Aged; Quinolones; Tenofovir; Treatment Outcome

Switching to a tenofovir alafenamide (TAF)-containing regimen has been reported to be associated with body weight gain in human immunodeficiency virus-infected subjects. We aimed to investigate the body weight change and virological, hepatic, and renal outcomes of TAF switching among chronic hepatitis B (CHB) patients.. This retrospective study included 121 CHB patients who were switched to TAF after >12 months of treatment with another nucleot(s)ide analog (NUC). All patients were monitored for 12 months.. In real-world NUC-experienced CHB patients, unexpected body weight gain was observed after TAF switching. The mechanism needs to be investigated in the future.

Topics: Adenine; Alanine; Body Weight; Female; Hepatitis B; Hepatitis B, Chronic; Humans; Male; Middle Aged; Retrospective Studies; Tenofovir

Hepatitis B virus (HBV) remains endemic in South Africa (SA), with a concomitantly high prevalence of HIV co-infection. Chronic kidney disease in these subpopulations also has a high prevalence. Tenofovir is an important component of management, but the associated risk of nephrotoxicity makes dosing a challenge in patients with impaired kidney function. A new formulation, tenofovir alafenamide fumarate (TAF), with a more favourable renal toxicity profile, is now available.. To evaluate our initial experience of TAF use at Groote Schuur Hospital, Cape Town.. We retrospectively reviewed patients with HBV mono-infection and HIV-HBV co-infection who were initiated on TAF since 2018. We recorded all relevant demographic, serological, virological and biochemical data from patient records. Adherence was documented by pill collection at the pharmacy.. A total of 26 patients were included in the evaluation, median (interquartile range (IQR)) age 48 (39 - 51) years, 73% (n=19) male, 27% (n=7) hepatitis B e-antigen-positive, and 46% (n=12) HIV co-infected. The median (IQR) duration of treatment with TAF was 13 (9 - 15) months. The median (IQR) baseline creatinine level was 180 (130 - 227) µmol/L, with significant improvement at 12 months, 122 (94 - 143) µmol/L; p=0.017. Reflecting this change, the estimated glomerular filtration rate improved significantly from baseline to month 12 (42 (25 - 52) and 51 (48 - 68) mL/min/1.73 m2, respectively; p=0.023). Similarly, serum alanine aminotransferase (ALT) normalised from a baseline of 33 (18 - 52) to 18 (15 - 24) U/L at month 12 (p=0.012). HBV DNA viral load also declined, from a baseline of log10 4.04 (2.5 - 7.8) IU/mL to a median of <log10 1.3 IU/mL at month 12. HIV viral load was less than the lower level of quantification at months 6 and 12.. TAF was well tolerated, with stable and significantly improving kidney function throughout a 12-month follow-up period. Serum ALT normalised, mirrored by declining HBV viral load. HIV viral load remained undetectable at 6 and 12 months.

Topics: Adult; Alanine; Antiviral Agents; Female; Follow-Up Studies; Glomerular Filtration Rate; Hepatitis B; Hepatitis B e Antigens; HIV Infections; Humans; Male; Middle Aged; Retrospective Studies; South Africa; Tenofovir; Treatment Outcome; Viral Load

Topics: Adenine; Alanine; Antibodies, Monoclonal, Humanized; Antiviral Agents; Fumarates; Hepatitis B; Hepatitis B virus; Humans; Psoriasis; Tenofovir; Tumor Necrosis Factor Inhibitors

Antenatal antiviral therapy (AVT) is effective in preventing mother-to-child transmission (MTCT) in chronic hepatitis B (CHB); tenofovir disoproxil fumarate (TDF) is the preferred agent. Tenofovir alafenamide (TAF) is a prodrug of tenofovir (TFV) similar to TDF, with improved bone and renal safety. There are no data on TAF breast milk pharmacokinetics and exposure to breastfeeding infants in CHB.. To assess the pharmacokinetics of TAF/TFV in breastfeeding women with CHB on TAF monotherapy.. Pregnant women with CHB requiring AVT commenced TAF 25 mg daily at third trimester or postpartum. Sample collection occurred while breastfeeding and taking TAF for minimum 4 weeks. Maternal blood, breast milk and infant urine samples were collected. Drug concentrations were measured by LCMS/MS analyses using validated methods. Non-compartmental analyses were performed to quantify the pharmacokinetic parameters.. In this first pharmacokinetic study of TAF monotherapy in breastfeeding women with CHB, concentrations of TAF and TFV were low in breast milk with negligible infant exposure, supporting the use of TAF to prevent MTCT.

Topics: Adenine; Adult; Alanine; Anti-HIV Agents; Female; Hepatitis B; Hepatitis B, Chronic; HIV Infections; Humans; Infectious Disease Transmission, Vertical; Milk, Human; Pregnancy; Tenofovir

Topics: Adenine; Alanine; Antiviral Agents; Female; Hepatitis B; Hepatitis B virus; Hepatitis B, Chronic; Humans; Pregnancy; Pregnant Women; Tenofovir

Topics: Adenine; Alanine; Antiviral Agents; Female; Hepatitis B; Hepatitis B, Chronic; Humans; Milk, Human; Mothers; Tenofovir

Although tenofovir alafenamide (TAF) and besifovir dipivoxil maleate (BSV) are potent antiviral agents in the treatment of chronic hepatitis B (CHB) infection, their renal safety profiles have not been previously compared. This study compared the risk of kidney function decline among patients with treatment-naïve CHB treated with TAF or BSV.. This multicenter, retrospective, longitudinal cohort study included 556 patients with treatment-naïve CHB treated with TAF (n = 366) or BSV (n = 190) between November 2017 and August 2021. The primary outcome was chronic kidney disease (CKD) progression, defined as an increase in CKD stage by at least one stage for at least three consecutive months.. 1:1 Propensity score matching yielded 154 patients in each treatment group. The mean estimated glomerular filtration rate (eGFR) was 100.4 vs. 100.3 ml/min/1.73 m. TAF and BSV showed a similar risk of kidney function decline in patients with treatment-naïve CHB. Further prospective randomized studies are warranted for validation.

Topics: Adenine; Alanine; Antiviral Agents; Guanine; Hepatitis B; Hepatitis B, Chronic; Humans; Kidney; Longitudinal Studies; Maleates; Organophosphonates; Renal Insufficiency, Chronic; Retrospective Studies; Tenofovir; Treatment Outcome

Current treatment options for patients infected with hepatitis B virus (HBV) are suboptimal, because the approved drugs rarely induce cure due to the persistence of the viral DNA genome in the nucleus of infected hepatocytes, and are associated with either severe side effects (pegylated interferon-alpha) or require life-long administration (nucleos(t)ide analogs). We report here the evaluation of the safety and therapeutic efficacy of a novel, humanized antibody (hzVSF) in the woodchuck model of HBV infection. hzVSF has been shown to act as a viral entry inhibitor, most likely by suppressing vimentin-mediated endocytosis of virions. Targeting the increased vimentin expression on liver cells by hzVSF after infection with HBV or woodchuck hepatitis virus (WHV) was demonstrated initially. Thereafter, hzVSF safety was assessed in eight woodchucks naïve for WHV infection. Antiviral efficacy of hzVSF was evaluated subsequently in 24 chronic WHV carrier woodchucks by monotreatment with three ascending doses and in combination with tenofovir alafenamide fumarate (TAF). Consistent with the proposed blocking of WHV reinfection, intravenous hzVSF administration for 12 weeks resulted in a modest but transient reduction of viral replication and associated liver inflammation. In combination with oral TAF dosing, the antiviral effect of hzVSF was enhanced and sustained in half of the woodchucks with an antibody response to viral proteins. Thus, hzVSF safely but modestly alters chronic WHV infection in woodchucks; however, as a combination partner to TAF, its antiviral efficacy is markedly increased. The results of this preclinical study support future evaluation of this novel anti-HBV drug in patients.

Topics: Alanine; Animals; Antibodies, Monoclonal, Humanized; Antiviral Agents; Disease Models, Animal; Drug Therapy, Combination; Endocytosis; Hep G2 Cells; Hepatitis B; Hepatitis B Virus, Woodchuck; Host-Pathogen Interactions; Humans; Liver; Marmota; Tenofovir; Vimentin; Viral Load; Virus Internalization; Virus Replication

Antiviral agents for chronic hepatitis B (CHB) reduced the risk of hepatocellular carcinoma (HCC) development. The outcomes of entecavir (ETV), tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide (TAF) were compared in patients with CHB.. Between 2017 and 2019, treatment-naïve patients with CHB treated with ETV, TDF, and TAF were recruited from three Korean tertiary institutes. The cumulative incidences of HCC and orthotopic liver transplantation (OLT) or mortality were calculated and compared using Kaplan-Meier analysis before and after trimatch.. Among recruited 2082 patients, 43 patients developed HCC, whereas 66 developed OLT or mortality. Before trimatch, the cumulative incidence of HCC was statistically similar among patients treated with three antiviral agents (p = 0.340). However, the cumulative probability of OLT or mortality development in patients treated with ETV or TDF was significantly higher than that of patients with TAF before trimatch (all p < 0.05). On multivariate analysis, male sex [hazard ratio (HR) 2.990] and older age (HR 1.044) were independently associated with an increased risk of HCC development, whereas higher platelet count (HR 0.993) was independently associated with a decreased risk (all p < 0.05). The type of antiviral agents did not significantly influence the risk of HCC and OLT or mortality development (all p > 0.05). After trimatch, no significant difference in the cumulative probability for HCC and OLT or mortality according to antiviral agents was found (all p > 0.05).. The outcomes of ETV, TDF, and TAF on the risk of HCC and OLT or mortality were statistically similar in treatment-naïve patients with CHB.

Topics: Aged; Alanine; Antiviral Agents; Carcinoma, Hepatocellular; Guanine; Hepatitis B; Hepatitis B, Chronic; Humans; Liver Neoplasms; Male; Tenofovir; Treatment Outcome

Few safety and effectiveness results have been published regarding the administration of tenofovir alafenamide fumarate (TAF) during pregnancy for the prevention of mother-to-child transmission (MTCT) of hepatitis B virus (HBV).. In this multicenter prospective observational study, pregnant women with HBV DNA levels higher than 200 000 IU/mL who received TAF or tenofovir disoproxil fumarate (TDF) from gestational weeks 24-35 to delivery were 1:1 enrolled and followed until postpartum month 6. Infants received immunoprophylaxis. The primary endpoint was the safety of mothers and infants. The secondary endpoint was the hepatitis B surface antigen (HBsAg)-positive rate at 7 months for infants.. In total, 116 and 116 mothers were enrolled, and 117 and 116 infants were born, in the TAF and TDF groups, respectively. TAF was well tolerated during a mean treatment duration of 11.0 weeks. The most common maternal adverse event was nausea (19.0%). One (0.9%), 3 (2.6%), and 9 (7.8%) mothers had abnormal alanine aminotransferase levels at delivery and at postpartum months 3 and 6, respectively. The TDF group had safety profiles that were comparable to those of the TAF group. No infants had birth defects in either group. The infants' physical and neurological development at birth and at 7 months in the TAF group were comparable with those in the TDF group. The HBsAg positive rate was 0% at 7 months in all 233 infants.. Antiviral prophylaxis with TAF was determined to be generally safe for both mothers and infants and reduced the MTCT rate to 0%.

Topics: Alanine; Antiviral Agents; Female; Hepatitis B; Hepatitis B, Chronic; Humans; Infant; Infant, Newborn; Infectious Disease Transmission, Vertical; Pregnancy; Pregnancy Complications, Infectious; Prospective Studies; Tenofovir; Viral Load

Standard literature procedures for the chemical synthesis of l-threose nucleosides generally employ l-ascorbic acid as starting material. Herein, we have explored two alternative routes that start from either l-arabitol or l-diethyl tartrate, both affording 2-

Topics: Adenine; Animals; Antiviral Agents; DNA, Circular; DNA, Viral; Drug Resistance, Viral; Guanine; Hepatitis B; Hepatitis B virus; Male; Mice; Mice, Inbred C57BL; Nucleosides; Prodrugs; Virus Replication

Whereas tenofovir disoproxil fumarate (TDF) can lead to renal adverse events, tenofovir alafenamide (TAF) has a more favorable renal safety profile. However, the impact of replacing TDF with TAF on renal function and liver parameters among HIV/hepatitis B virus (HBV)-coinfected individuals with renal dysfunction remains unclear.. We included all participants from the Swiss HIV Cohort Study with an HIV/HBV coinfection who switched from TDF to TAF and had an estimated glomerular filtration rate (eGFR) <90 mL/min/1.73 m and a suppressed HIV viral load (<200 cp/mL). We assessed changes in eGFR, urine protein-to-creatinine ratio, and alanine aminotransferase (ALT) after 1 year using mixed-effect models with interrupted time series.. Among 106 participants (15.1% women, median age 53 years), eGFR was 60-89 mL/min/1.73 m in 84 (79.2%) and <60 mL/min/1.73 m in 22 (20.8%) individuals at the time of switch. One year after the switch from TDF to TAF, individuals with an eGFR between 60 and 89 mL/min/1.73 m experienced increases in eGFR of 3.2 mL/min/1.73 m (95% confidence interval [CI] 1.2 to 5.2), whereas those with an eGFR <60 mL/min/1.73 m experienced improvements of 6.2 mL/min/1.73 m (95% CI 2.4 to 10.0). Urine protein-to-creatinine ratio decreased overall (-6.3 mg/mmol, 95% CI -10.0 to -2.7), and ALT levels declined in patients with elevated baseline levels (-11.8 IU/L, 95% CI -17.3 to -6.4) 1 year after replacing TDF with TAF.. Switching from TDF to TAF among HIV/HBV-coinfected individuals with renal impairment led to improvements in eGFR, a decline in proteinuria, and to ALT normalization in those with elevated ALT levels.

Topics: Adenine; Aged; Alanine; Anti-HIV Agents; Female; Glomerular Filtration Rate; Hepatitis B; Hepatitis B virus; HIV Infections; Humans; Interrupted Time Series Analysis; Kidney Diseases; Kidney Function Tests; Liver; Male; Middle Aged; Prospective Studies; Tenofovir; Viral Load

Fatal lactic acidosis has been reported while on the treatment with Nucleoside/nucleotide analogues (NA) for the treatment of hepatitis B, C and HIV. No cases of such a complication have been reported in hematopoietic stem cell transplant (HSCT) recipients. We present a 65-year male who underwent autologous HSCT for the treatment of multiple myeloma. Prior to transplant he was started on single agent tenofovir alafenamide (TAF) for treatment of resolved hepatitis B infection. He presented few weeks later with severe lactic acidosis. Other causes of lactic acidosis were excluded. The patient died of multi-organ failure despite stopping TAF and aggressive supportive care. The case demonstrates the need for increased awareness of this potential complication of NA treatment in the course of transplantation.

Topics: Acidosis, Lactic; Adenine; Aged; Alanine; Antiviral Agents; Fatal Outcome; Hematopoietic Stem Cell Transplantation; Hepatitis B; Hepatitis C; HIV Infections; Humans; Male; Multiple Myeloma; Tenofovir; Transplantation, Autologous

Tenofovir alafenamide (TAF) is a novel prodrug of tenofovir (TFV). This study evaluated the antiviral activity of TAF against wild-type genotype A-H HBV clinical isolates as well as adefovir-resistant, lamivudine-resistant, and entecavir-resistant HBV isolates. Full length HBV genomes or the polymerase/reverse transcriptase (pol/RT) region from treatment-naïve patients infected with HBV genotypes A-H were amplified and cloned into an expression vector under the control of a CMV promoter. In addition, 11 drug resistant HBV constructs were created by site-directed mutagenesis of a full length genotype D construct. Activity of TAF was measured by transfection of each construct into HepG2 cells and assessment of HBV DNA levels following treatment across a range of TAF concentrations. TAF activity in vitro was similar against wild-type genotype A-H HBV clinical isolates. All lamivudine- and entecavir-resistant isolates and 4/5 adefovir-resistant isolates were found to be sensitive to inhibition by TAF in vitro as compared to the wild-type isolate. The adefovir-resistant isolate rtA181V + rtN236T exhibited low-level reduced susceptibility to TAF. TAF is similarly active in vitro against wild-type genotype A-H HBV clinical isolates. The TAF sensitivity results for all drug-resistant isolates are consistent with what has been observed with the parent drug TFV. The in vitro cell-based HBV phenotyping assay results support the use of TAF in treatment of HBV infected subjects with diverse HBV genotypes, in both treatment-naive and treatment-experienced HBV infected patients.

Topics: Adenine; Alanine; Antiviral Agents; Drug Resistance, Viral; Genotype; Hep G2 Cells; Hepatitis B; Hepatitis B virus; Humans; Mutagenesis, Site-Directed; Phenotype; Prodrugs; Tenofovir; Virus Replication