3-year Treatment of Tenofovir Alafenamide vs. Tenofovir Disoproxil Fumarate for Chronic HBV Infection in China

Current trends and advances in antiviral therapy for chronic hepatitis B

ABSTRACT

Chronic hepatitis B virus (HBV) infection is a global public health concern. Existing antiviral drugs, including nucleos(t)ide analogs and interferon-α, can suppress HBV replication and improve the prognosis. However, the persistence of covalently closed circular DNA (cccDNA), the integration of HBV-DNA into the host genome, and compromised immune responses impede the successful treatment of hepatitis B. While achieving a functional cure of HBV remains elusive with the current treatment methods, this is the goal of new therapeutic approaches. Therefore, developing novel antiviral drugs is necessary for achieving a functional or complete cure for chronic hepatitis B. In recent years, substantial progress has been made in drug discovery and development for HBV infection. Direct-acting antiviral agents such as entry inhibitors, capsid assembly modulators, subviral particle release inhibitors, cccDNA silencers, and RNA interference molecules have entered clinical trials. In addition, several immunomodulatory agents, including toll-like receptor agonists, therapeutic vaccines, checkpoint inhibitors, and monoclonal antibodies, are also making their way toward clinical use. In this review, we summarize the recent progress and limitations of chronic hepatitis B treatment and discuss perspectives on approaches to achieving functional cure. Although it will take some time for these new antiviral drugs to be widely used in clinical practice, combination therapy may become a preferable treatment option in the future.

Five-year Treatment with Tenofovir Alafenamide Achieves High Rates of Viral Suppression, Alanine Aminotransferase Normalization, and Favorable Bone and Renal Safety in Chinese Chronic Hepatitis B Patients

Background and Aims

After 3-years (144 week) of double-blind treatment in Chinese chronic hepatitis B patients in two ongoing phase 3 studies, tenofovir alafenamide (TAF) showed similar efficacy to tenofovir disoproxil fumarate (TDF), with improved renal and bone safety. In this study, we aimed to report the 5-year results from 2 years into the open-label TAF treatment phase.

Methods

All participants completing the 144-week double-blind treatment were eligible to receive open-label TAF 25 mg once daily up to week 384. Serial analysis of viral suppression (hepatitis B virus DNA <29 IU/mL), alanine aminotransferase normalization, serological responses, and safety outcomes at year 5 (week 240) was performed.

Results

The open-label phase included 93% (311/334) of the enrolled participants, which included 212 who switched from double-blind TAF to open-label TAF (TAF-TAF) and 99 who switched from double-blind TDF to open-label TAF (TDF-TAF). Baseline characteristics were comparable. Week 240 viral suppression rates were similar between groups [93.4% vs. 93.9%; difference: -1.5%, (95% CI: -6.4 to -3.5), p=0.857]. Alanine aminotransferase normalization and serological response rates were higher in the TAF-TAF group than in the TDF-TAF group. The frequencies of adverse events and laboratory abnormalities were low and similar between groups. Both groups had similar small numerical declines from baseline in estimated glomerular filtration rate at year 5 (week 240, -2.85 mL/min vs. -3.29 mL/min, p=0.910). The greater declines in renal and bone parameters in the TDF-TAF group through week 144 improved after switching to TAF.

Conclusions

The 5-year TAF treatment efficacy was high and similar to that of 3-year TDF followed by 2-year TAF in Chinese chronic hepatitis B patients. Favorable effects on bone and renal parameters were sustained with TAF treatment alone and were observed following the switch from TDF to TAF.

Atherosclerotic cardiovascular disease risk profile of patients with chronic hepatitis B treated with tenofovir alafenamide or tenofovir disoproxil fumarate for 96 weeks

BACKGROUND

Patients with chronic hepatitis B (CHB) who switch from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) show changes in lipid profiles.

AIM

To evaluate how these changes affect cardiovascular risk.

METHODS

This pooled analysis, based on two large prospective studies, evaluated fasting lipid profiles of patients with CHB who were treated with TAF 25 mg/day or TDF 300 mg/day for 96 weeks. Patients who fulfilled the American College of Cardiology criteria (age 40-79 years, high-density lipoprotein [HDL] 20-100 mg/dL, total cholesterol [TC] 130-320 mg/dL and systolic blood pressure 90-200 mmHg) required to assess 10-year atherosclerotic cardiovascular disease (ASCVD) risk with baseline lipid data and at least one post-baseline measurement were included in the ASCVD-risk population. The 10-year ASCVD risk was calculated for patients in this population, and changes from baseline to Week 96 were assessed using intermediate- (≥7.5%) and high-risk (≥20%) cut-offs.

RESULTS

Among 1632 patients, 620 (38%) met the criteria for the ASCVD-risk population. At Week 96, fasting levels of all lipids, except TC:HDL ratio, were lower with TDF than TAF. No significant increase was observed in overall ASCVD risk or in any ASCVD-risk categories during the 96-week treatment period compared with baseline. A similar proportion of patients in the TAF and TDF treatment groups (1.3% and 2.3%, respectively; p = 0.34) reported cardiovascular events.

CONCLUSION

Despite on-treatment differences in lipid profiles with TAF and TDF, predicted cardiovascular risk and clinical events were similar for both groups after 96 weeks.

Immunomodulatory and Antiviral Therapy Improved Functional Cure Rate in CHB Patients with High HBsAg Level Experienced NA

Background and Aims

A functional cure, or hepatitis B virus (HBV) surface antigen (HBsAg) loss, is difficult to achieve in patients with hepatitis B virus e antigen (HBeAg)-positive chronic hepatitis B. The HBV vaccine and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been reported to help reduce HBsAg levels and promote HBsAg loss. In this prospective randomized trial, we evaluated HBsAg loss in patients receiving pegylated interferon-α2b (PEGIFN-α2b) and tenofovir disoproxil fumarate (TDF), with and without GM-CSF and HBV vaccination.

Methods

A total of 287 patients with HBeAg positive chronic hepatitis B and seroconversion after nucleot(s)ide analog treatment were assigned randomly to three treatment groups for 48 weeks, TDF alone (control), PEGIFN-α2b + TDF, and PEGIFN-α2b + TDF + GM-CSF + HBV vaccine. The primary endpoints were the proportions of patients with HBsAg loss and seroconversion at 48 and 72 weeks.

Results

The cumulative HBsAg loss rates in the control, PEGIFN-α2b + TDF, and PEGIFN-α2b + TDF + GM-CSF + HBV vaccine groups at week 48 were 0.0%, 28.3%, and 41.1%, respectively. The cumulative HBsAg seroconversion rates in these groups at week 48 were 0.0%, 21.7%, and 33.9%, respectively. Multivariate regression analysis showed that GM-CSF use plus HBV vaccination was significantly associated with HBsAg loss (p=0.017) and seroconversion (p=0.030).

Conclusions

In patients with HBeAg-positive chronic hepatitis B and seroconversion after nucleot(s)ide analog treatment, immunomodulatory/antiviral treatment regimens effectively improved HBsAg loss, and the regimen including GM-CSF and HBV vaccination was most effective.

Tenofovir alafenamide and tenofovir disoproxil fumarate reduce incidence of hepatocellular carcinoma in patients with chronic hepatitis B

Background & Aims

Antiviral therapy may attenuate the risk of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B (CHB). We aimed to explore how tenofovir alafenamide (TAF) and tenofovir disoproxil fumarate (TDF) affect HCC risk in patients with CHB.

Methods

The REACH-B, aMAP, and mPAGE-B models were utilized to assess HCC risk in patients with CHB from two global randomized-controlled trials evaluating the impact of TAF vs. TDF treatment. Standard incidence ratios (SIRs) were calculated using data from the REACH-B model as a ratio of observed HCC cases in the TAF- or TDF-treated patients vs. predicted HCC cases for untreated historical controls. Proportions of treated patients shifting aMAP and mPAGE-B risk categories between baseline and Week 240 were calculated.

Results

Of the 1,632 patients (TAF, n = 1,093; TDF, n = 539) followed for up to 300 weeks, 22 HCC cases developed. Those receiving TAF had an SIR that was lower compared to the SIR of individuals receiving TDF: 0.32 (p <0.001) vs. 0.56 (p = 0.06). In the general study population, individuals without cirrhosis at baseline had an SIR that was lower compared to the SIR of individuals with cirrhosis at baseline: 0.37 (p <0.001) vs. 0.58 (p = 0.15). Of the patients at low risk of HCC at baseline, the majority (97%) remained low risk by mPAGE-B and aMAP scoring at Week 240. Among those at medium or high risk at baseline, substantial portions shifted to a lower risk category by Week 240 (mPAGE-B: 22% and 42%; aMAP: 39% and 63%, respectively).

Conclusions

This evaluation provides evidence that treatment with TAF or TDF can reduce HCC risk in patients with CHB, particularly in patients without cirrhosis.

Impact and implications

Despite the substantial impact of HCC on long-term outcomes of patients with CHB, the differential risk of HCC development among those receiving treatment with TAF vs. TDF has not been well elucidated. Using three validated risk prediction models, we found that TAF is at least as effective as TDF in reducing HCC risk in patients with CHB. While TDF is well-studied in the context of HCC risk reduction, our novel findings underscore the effectiveness of TAF as a treatment option for patients with CHB.

Clinical trial numbers

NCT01940341; NCT02836249; NCT01940471; NCT02836236.

Awareness of HBV Functional Cure and Attitude Toward Related Clinical Trials Among Patients with Chronic Hepatitis B in China

Purpose

HBV functional cure is an optimal treatment goal for chronic hepatitis B (CHB) at present and numerous new drugs aiming for HBV functional cure are in development. We carried out an internet-based survey to understand the treatment status, unmet needs, awareness of HBV functional cure and attitude toward related clinical trials among CHB patients in China.

Patients and Methods

An internet-based anonymous survey was conducted on CHB patients who reside in mainland China. Determinants of awareness and attitude were identified by logistic regression models.

Results

Of the 1220 CHB patients who completed the survey questionnaire, 11.1% (135/1220) were aware of HBV functional cure and 50.2% (612/1220) answered "definitely will" to participate in related clinical trials. Participants who knew their HBsAg level (HBsAg<1500 IU/mL: OR=3.03, 95% CI: 1.87-4.92; HBsAg≥1500 IU/mL: OR=2.57, 95% CI: 1.35-4.88), who expected to achieve HBsAg loss with treatment (OR=1.63, 95% CI: 1.07-2.50) and who were dissatisfied with current treatment due to the failure of achieving HBsAg loss (OR=1.67, 95% CI: 1.10-2.53) had better awareness of HBV functional cure. Participants who had HBsAg level less than 1500 IU/mL (OR=1.45, 95% CI: 1.05-1.99), treatment with pegylated interferon alpha with or without nucleos(t)ide (OR=1.68, 95% CI: 1.11-2.53) and better awareness of HBV functional cure (OR=1.62, 95% CI: 1.01-2.61) were more likely to say "definitely will" to participate in related clinical trials.

Conclusion

Chinese CHB patients reported a low awareness of HBV functional cure. Although CHB patients in China reported a low rate of HBV functional cure awareness, they had a high acceptance of related clinical trials.

Comparison of Pegylated Interferon Alfa Therapy in Combination with Tenofovir Alafenamide Fumarate or Tenofovir Disoproxil Fumarate for Treatment of Chronic Hepatitis B Patients

Purpose

The study aims to evaluate the effectiveness of a tenofovir alafenamide fumarate (TAF) and pegylated interferon alfa (PegIFN-α) regimen compared to a tenofovir disoproxil fumarate (TDF) and PegIFN-α therapy in patients with chronic hepatitis B (CHB).

Patients and Methods

Patients who were treated with PegIFN-α in combination with TAF or TDF were retrospectively enrolled. The primary outcome measured was the HBsAg loss rate. The rates of virological response, serological response for HBeAg, and normalization of alanine aminotransferase (ALT) were also calculated. The cumulative incidences of response rates were compared between the two groups using Kaplan-Meier analysis.

Results

A total of 114 patients were retrospectively enrolled in the study, with 33 receiving TAF plus PegIFN-α treatment and 81 receiving TDF plus PegIFN-α treatment. The HBsAg loss rate for the TAF plus PegIFN-α group was 15.2% at 24 weeks and 21.2% at 48 weeks, while the TDF plus PegIFN-α group had rates of 7.4% at 24 weeks and 12.3% at 48 weeks (P=0.204 at 24 weeks, P=0.228 at 48 weeks). In subgroup analysis of HBeAg positive patients, the TAF group had a higher HBsAg loss rate of 25% at week 48, compared to 3.8% in the TDF group (P=0.033). According to Kaplan-Meier analysis, the TAF plus PegIFN-α group achieved virological response more quickly than the TDF plus PegIFN-α group (p=0.013). There was no statistical difference in HBeAg serological rate or ALT normalization rate.

Conclusion

There was no significant difference in the HBsAg loss between the two groups. However, subgroup analysis revealed that TAF plus PegIFN-α treatment had a higher HBsAg loss rate than TDF plus PegIFN-α treatment in HBeAg-positive patients. Additionally, TAF plus PegIFN-α treatment demonstrated better virological suppression for CHB patients. Therefore, TAF plus PegIFN-α treatment regimen is recommended for CHB patients who aim to achieve functional cure.

Retreatment Efficacy and Renal Safety of Tenofovir Alafenamide, Entecavir, and Tenofovir Disoproxil Fumarate After Entecavir or Tenofovir Cessation

BACKGROUND

We aimed to compare the one-year retreatment efficacy and renal safety of entecavir, tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide (TAF) after HBV relapse in patients who discontinued entecavir or TDF.

METHODS

This retrospective study included 289 chronic hepatitis B (CHB) patients without cirrhosis who received entecavir (n = 93), TDF (n = 103), or TAF (n = 86) retreatment for at least 12 months after entecavir or TDF cessation.

RESULTS

The rate of virological response (HBV DNA < 20 IU/mL) at 12 months of retreatment was 79/93 (84.9%) in the entecavir group, 92/103 (89.3%) in the TDF group, and 72/86 (83.7%) in the TAF group. The rate of ALT normalization (ALT ≤ 40 U/L) after 12 months of retreatment was 76/93 (81.7%) in the entecavir group, 77/103 (74.7%) in the TDF group , and 73/86 (84.9%) in the TAF group. There was no significant difference in the rates of virological response (p = 0.495) and ALT normalization (p = 0.198) among the three groups. Multivariate analysis showed that lower HBV DNA and HBsAg levels at baseline were independently associated with virological response at 12 months of retreatment. The TDF group (37.8 ± 34.8 U/L) had higher ALT levels at 12 months of retreatment than the TAF (27. ± 17.9 U/L, p = 0.015) and entecavir (28.3 ± 19.3 U/L, p = 0.022) groups. In patients with eGFR 60-90 mL/min/1.73 m², eGFR change between baseline and 12 months of retreatment increased in the entecavir and TAF groups and decreased in the TDF group.

CONCLUSIONS

TAF could be one of the retreatment options for retreatment of HBV relapse after entecavir or TDF cessation.

An ultralong-acting tenofovir ProTide nanoformulation achieves monthslong HBV suppression

Treatment of chronic hepatitis B virus (HBV) requires lifelong daily therapy. However, suboptimal adherence to the existing daily therapy has led to the need for ultralong-acting antivirals. A lipophilic and hydrophobic ProTide was made by replacing the alanyl isopropyl ester present in tenofovir alafenamide (TAF) with a docosyl phenyl alanyl ester, now referred to as M1TFV. NM1TFV and nanoformulated TAF (NTAF) nanocrystals were formulated by high-pressure homogenization. A single intramuscular injection of NM1TFV, but not NTAF, delivered at a dose of TFV equivalents (168 milligrams per kilogram) demonstrated monthslong antiviral activities in both HBV-transgenic and human hepatocyte transplanted TK-NOG mice. The suppression of HBV DNA in blood was maintained for 3 months. Laboratory experiments on HBV-transfected HepG2.2.15 cells affirmed the animal results and the critical role of docosanol in the sustained NM1TFV antiviral responses. These results provide clear "proof of concept" toward an emerging therapeutic paradigm for the treatment and prevention of HBV infection.

Efficacy and safety of tenofovir alafenamide fumarate in nucleoside analogue treatment-naïve patients with chronic hepatitis B

Tenofovir alafenamide fumarate (TAF) is a first-line drug for the antiviral treatment of patients with chronic hepatitis B (CHB) in China. In the present study, the efficacy and renal safety of TAF were evaluated in treatment-naive patients with CHB. Patients with CHB who had not been previously treated with nucleoside analogues (NAs) were recruited before TAF treatment was initiated. Changes in the levels of hepatitis B virus (HBV) DNA, hepatitis B e antigen (HBeAg) and hepatitis B surface antigen (HBsAg) were analyzed at 24 and 48 weeks using immunoassays. In addition, liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) were analyzed using transient elastography, while alanine aminotransferase (ALT), triglyceride (TG), total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels, calcium (Ca) and inorganic phosphorus (IP) levels were measured using biochemistry assay. In addition, the estimated glomerular filtration rate (eGFR) was calculated. After 48 weeks, the ALT normalization rate was 95.24% (40/42), the complete virological response (HBV DNA <20 IU/ml) rate was 69.05% (29/42) and the HBeAg seroconversion rate was 8.57% (3/35). The levels of HBV DNA and HBsAg were significantly decreased from the baseline at 5.49±1.95 to 1.26±0.66 log₁₀ IU/ml and from 3.59±0.81 to 3.32±0.55 log₁₀ IU/ml after 48 weeks of treatment, respectively. Compared with that in the baseline measurements, LSM at 48 weeks was significantly decreased from 13.00±8.15 to 8.66±4.45 kPa. No significant differences were observed in the TG, TC, LDL-C, CAP, eGFR, Ca and IP measurements. According to the baseline ALT levels, patients were divided into group A [ALT ≤1 x upper limit of normal (ULN); ULN=50 U/l; n=21], group B (1 x ULN < ALT <2 x ULN; n=22) and group C (ALT ≥2 x ULN; n=18). A significant decrease in HBsAg levels was observed in group B (3.63±0.68 vs. 3.53±0.63 log₁₀ IU/ml) and group C (4.15±0.57 vs. 3.66±0.48 log₁₀ IU/ml) at 24 weeks compared with the baseline. In conclusion, TAF was found to be effective and safe in NA treatment-naive patients with CHB. Moreover, the higher the ALT levels, the more prominent the curative effect from TAF treatment. Therefore, NA treatment-naive CHB patients could benefit from TAF treatment in real world.