Compare with safety and efficacy of entecavir and adefovir dipivoxil combination therapy and tenofovir disoproxil fumarate monotherapy for chronic hepatitis B patient with adefovir-resistant

Objective: To compare the 2-year efficacy and safety of combination therapy with entecavir (ETV) and adefovir dipivoxil (ADV) to that of tenofovir disoproxil fumarate (TDF) monotherapy in treatment of patients with adefovir drug-resistant chronic hepatitis B. Methods: HBeAg-positive CHB patients (n = 100) with adefovir-resistance (rtA181T/V and/or rtN236T) were enrolled. Patients were treated with either ETV 0.5 mg plus ADV 10 mg per day (n = 52) or TDF 300 mg per day (n = 48) for 48 weeks. Tests for liver and kidney function, Serum Phosphorus, HBV serum markers, HBV DNA load and ultrasonography of liver were performed every 3 months. Student's t-test and χ² test were used to compare the efficacy, side effects in the two groups. Results: Fifty-two patients in ETV + ADV group and forty-eight patients in TDF group were followed-up for 96 weeks. HBV DNA undetectable rate were 76.9% versus 81.3% (P = 0.631) at week 48, and 92.3% versus 95.8% (P = 0.679) at week 96 in ETV + ADV combination therapy and TDF monotherapy group respectively. Serum ALT normalized rate were 84.6% versus 87.5% (P = 0.777) at week 48, and 92.3% versus 95.8% (P = 0.679) at week 96 in ETV+ADV combination therapy and TDF monotherapy group respectively. But the level of serum Phosphorus was significantly lower in ETV + ADV combination therapy group compare with TDF monotherapy group (1.13 ±0.15 versus 1.22 ±0.16, P = 0.004) at week 96. Conclusion: Both ETV + ADV combination therapy and TDF monotherapy provided effective treatments in chronic hepatitis B with adefovir-resistant. However, it was associated with poor serological responses up to week 96. The long term treatment of hepatitis B with ETV (0.5 mg/day) combination of ADV (10 mg/day) can potentially cause hypophosphatemia and renal impairment, so regular monitoring of serum phosphate, serum creatinine and evaluation of eGFR is needed.

Dolutegravir plus Two Different Prodrugs of Tenofovir to Treat HIV

BACKGROUND

Two drugs under consideration for inclusion in antiretroviral therapy (ART) regimens for human immunodeficiency virus (HIV) infection are dolutegravir (DTG) and tenofovir alafenamide fumarate (TAF). There are limited data on their use in low- and middle-income countries.

METHODS

We conducted a 96-week, phase 3, investigator-led, open-label, randomized trial in South Africa, in which we compared a triple-therapy combination of emtricitabine (FTC) and DTG plus either of two tenofovir prodrugs - TAF (TAF-based group) or tenofovir disoproxil fumarate (TDF) (TDF-based group) - against the local standard-of-care regimen of TDF-FTC-efavirenz (standard-care group). Inclusion criteria included an age of 12 years or older, no receipt of ART in the previous 6 months, a creatinine clearance of more than 60 ml per minute (>80 ml per minute in patients younger than 19 years of age), and an HIV type 1 (HIV-1) RNA level of 500 copies or more per milliliter. The primary end point was the percentage of patients with a 48-week HIV-1 RNA level of less than 50 copies per milliliter (as determined with the Snapshot algorithm from the Food and Drug Administration; noninferiority margin, -10 percentage points). We report the primary (48-week) efficacy and safety data.

RESULTS

A total of 1053 patients underwent randomization from February 2017 through May 2018. More than 99% of the patients were black, and 59% were female. The mean age was 32 years, and the mean CD4 count was 337 cells per cubic millimeter. At week 48, the percentage of patients with an HIV-1 RNA level of less than 50 copies per milliliter was 84% in the TAF-based group, 85% in the TDF-based group, and 79% in the standard-care group, findings that indicate that the DTG-containing regimens were noninferior to the standard-care regimen. The number of patients who discontinued the trial regimen was higher in the standard-care group than in the other two groups. In the per-protocol population, the standard-care regimen had equivalent potency to the other two regimens. The TAF-based regimen had less effect on bone density and renal function than the other regimens. Weight increase (both lean and fat mass) was greatest in the TAF-based group and among female patients (mean increase, 6.4 kg in the TAF-based group, 3.2 kg in the TDF-based group, and 1.7 kg in the standard-care group). No resistance to integrase inhibitors was identified in patients receiving the DTG-containing regimens.

CONCLUSIONS

Treatment with DTG combined with either of two tenofovir prodrugs (TAF and TDF) showed noninferior efficacy to treatment with the standard-care regimen. There was significantly more weight gain with the DTG-containing regimens, especially in combination with TAF, than with the standard-care regimen. (ADVANCE ClinicalTrials.gov number, NCT03122262.).

Efficacy of long-term tenofovir disoproxil fumarate therapy in chronic hepatitis B patients with partial virologic response in real practice

BACKGROUND/AIMS

The optimal management of chronic hepatitis B (CHB) patients with partial virologic response (PVR) to tenofovir disoproxil fumarate (TDF) remains unclear. We aimed to evaluate the long-term efficacy of prolonged TDF therapy in treatment-naïve CHB patients with PVR to TDF therapy in real practice.

METHODS

We retrospectively investigated the efficacy of prolonged TDF therapy in treatment-naïve CHB patients with PVR to TDF. PVR was defined as a decrease in serum hepatitis B virus (HBV) DNA over 2 log10 IU/mL from baseline, with detectable HBV DNA by real-time polymerase chain reaction at week 48.

RESULTS

We included 232 patients who underwent TDF therapy for over 48 weeks. Forty-two patients (18.1%) showed PVR. In multivariate analysis, hepatitis B e antigen (HBeAg) positivity, and high levels of serum HBV DNA at baseline and week 12 were independent predictive factors for PVR during TDF therapy. Out of 42 patients with PVR, 39 (92.9%) achieved virologic response (VR) during continuous TDF treatment; the cumulative VR rates at 24, 36, and 48 months were 79.8%, 88.2%, and 95.6%, respectively. With an additional 12 months of therapy, VR was achieved in 28/31 (90.3%) patients with HBV DNA < 100 IU/mL, compared to 5/11 (45.5%) patients with HBV DNA ≥ 100 IU/mL, at week 48.

CONCLUSION

The vast majority of patients achieved VR through prolonged TDF therapy, thus TDF treatment can be maintained in nucleos(t)ide-naïve patients with PVR at week 48, especially in those with low viremia.

Factors Associated With Sex-Related Pre-exposure Prophylaxis Adherence Among Men Who Have Sex With Men in New York City in HPTN 067

BACKGROUND

HPTN 067 assessed the feasibility of daily and non-daily dosing of open-label emtricitabine/tenofovir disoproxil fumarate (FTC/TDF)-based pre-exposure prophylaxis (PrEP).

METHODS

Factors associated with sex-related PrEP adherence were assessed among men who have sex with men (MSM) randomized to one of 3 PrEP dosing arms in HPTN 067 in New York City. Sex-related PrEP adherence was defined per protocol as at least 1 PrEP tablet taken within 4 days pre-sex and at least 1 additional PrEP tablet taken within 24 hours post-sex, assessed via electronic drug monitoring and weekly interviews. Demographic data and behavioral measures were evaluated for association with sex-related PrEP adherence. Logistic regression for clustered data was used to estimate the unadjusted and adjusted odds ratios.

RESULTS

Of 176 randomized MSM participants, 59% were Black, 10% White, 25% Hispanic, and 6% other; median age was 31 years. In the multivariable analyses, higher sex-related PrEP adherence was significantly associated with daily dosing arm, older age, employment, and higher PrEP adherence behavioral skills. Lower sex-related PrEP adherence was significantly associated with identifying as Black or Hispanic (compared with White), opiate use, and reporting "I forgot" as an adherence barrier.

CONCLUSIONS

This analysis identified populations of MSM who might benefit from additional support to optimize PrEP adherence, including those who are younger, unemployed, or opiate users. MSM with lower PrEP behavioral skills may benefit from targeted interventions. Further study is needed to assess racial and ethnic disparities in PrEP adherence, which may reflect broader social and economic inequalities not captured in this study.

Choice of antiretroviral drugs for continued treatment scale-up in a public health approach: what more do we need to know?

INTRODUCTION

There have been several important developments in antiretroviral treatment in the past two years. Randomized clinical trials have been conducted to evaluate a lower dose of efavirenz (400 mg once daily). Integrase inhibitors such as dolutegravir have been approved for first-line treatment. A new formulation of tenofovir (alafenamide) has been developed and has shown equivalent efficacy to tenofovir in randomized trials. Two-drug combination treatments have been evaluated in treatment-naïve and -experienced patients. The novel pharmacokinetic booster cobicistat has been compared to ritonavir in terms of pharmacokinetics, efficacy and safety. The objective of this commentary is to assess recent developments in antiretroviral drug treatment to determine whether new treatments should be included in new international guidelines.

DISCUSSION

The use of first-line treatment with tenofovir and efavirenz at the standard 600 mg once-daily dose should remain the first-choice standard of care treatment. Evidence supporting a switch to efavirenz 400 mg once daily or integrase inhibitors is sufficient to consider these drugs as alternative first-line options, but more data are needed on their use in pregnant women and people with TB co-infection. The use of new formulations of tenofovir is currently too preliminary to justify immediate adoption and scale-up across HIV programmes in low- and middle-income countries. The evidence supporting use of two-drug combinations is not considered strong enough to justify changed recommendations from use of standard triple drug combinations. Cobicistat does not offer significant safety advantages over ritonavir as a pharmacokinetic booster.

CONCLUSIONS

For continued scale-up of antiretroviral treatment in low- and middle-income countries, use of first-line triple combinations including efavirenz 600 mg once daily is supported by the largest evidence base. Additional studies are underway to evaluate new treatments in key populations, and these results may justify changes to these recommendations.

[Pharmacokinetics of tenofovir in Beagle dogs after oral dosing of tenofovir dipivoxil fumarate using HPLC-MS/MS analysis]

A simple, rapid and sensitive method was developed for the quantification of tenofovir in plasma of Beagle dogs using HPLC-MS/MS analysis. The analytes tenofovir and internal standard (IS) adefovir were separated on a Zorbax SB-C18 column (3.5 microm, 100 mm x 2.1 mm, Agilent, USA) with mobile phase of methanol/water containing 0.3% formic acid using a gradient elution mode at a flow rate of 0.2 mL x min(-1). The plasma sample preparation was a simple deproteinization by the addition of 20% trichloroacetic acid followed by centrifugation. The detection was performed in positive selected reaction monitoring (SRM) mode with an electrospray ionization (ESI) source. The reactions monitored were m/z 288.1-176.2 for tenofovir and m/z 274.1-162.2 for adefovir (IS). Linear detection responses were obtained for tenofovir ranging from 10 to 5 000 ng x mL(-1). The intra- and inter-day precisions (RSD%) was no more than 6.3% with high recovery and good stability for the quantification, indicating the present method was specific, fast, accurate and reliable. The method was successfully applied to the pharmacokinetic study of two tenofovir agents. Tenofovir dipivoxil fumarate (BP0018, test agent) and tenofovir disoproxil fumarate (reference agent) were orally administrated to 8 Beagle dogs according to the 2 x 2 crossover design. Comparing with the reference agent, the longer MRT and t1/2 were obtained in the group of BP0018, while no significant difference was observed in AUC(0-t), AUC(0-infinity), C(max) and t(max) between them, suggesting that tenofovir dipivoxil fumarate was bioequivalent to the tenofovir disoproxil fumarate in Beagle dogs.

MTN-001: randomized pharmacokinetic cross-over study comparing tenofovir vaginal gel and oral tablets in vaginal tissue and other compartments

Background

Oral and vaginal preparations of tenofovir as pre-exposure prophylaxis (PrEP) for human immunodeficiency virus (HIV) infection have demonstrated variable efficacy in men and women prompting assessment of variation in drug concentration as an explanation. Knowledge of tenofovir concentration and its active form, tenofovir diphosphate, at the putative vaginal and rectal site of action and its relationship to concentrations at multiple other anatomic locations may provide key information for both interpreting PrEP study outcomes and planning future PrEP drug development.

Objective

MTN-001 was designed to directly compare oral to vaginal steady-state tenofovir pharmacokinetics in blood, vaginal tissue, and vaginal and rectal fluid in a paired cross-over design.

Methods and Findings

We enrolled 144 HIV-uninfected women at 4 US and 3 African clinical research sites in an open label, 3-period crossover study of three different daily tenofovir regimens, each for 6 weeks (oral 300 mg tenofovir disoproxil fumarate, vaginal 1% tenofovir gel [40 mg], or both). Serum concentrations after vaginal dosing were 56-fold lower than after oral dosing (p<0.001). Vaginal tissue tenofovir diphosphate was quantifiable in ≥90% of women with vaginal dosing and only 19% of women with oral dosing. Vaginal tissue tenofovir diphosphate was ≥130-fold higher with vaginal compared to oral dosing (p<0.001). Rectal fluid tenofovir concentrations in vaginal dosing periods were higher than concentrations measured in the oral only dosing period (p<0.03).

Conclusions

Compared to oral dosing, vaginal dosing achieved much lower serum concentrations and much higher vaginal tissue concentrations. Even allowing for 100-fold concentration differences due to poor adherence or less frequent prescribed dosing, vaginal dosing of tenofovir should provide higher active site concentrations and theoretically greater PrEP efficacy than oral dosing; randomized topical dosing PrEP trials to the contrary indicates that factors beyond tenofovir’s antiviral effect substantially influence PrEP efficacy.

Trial Registration

ClinicalTrials.gov NCT00592124