Improved pharmacokinetics of tenofovir ester prodrugs strengthened the inhibition of HBV replication and the rebalance of hepatocellular metabolism in preclinical models

Effectiveness and Safety of Tenofovir Amibufenamide in the Treatment of Chronic Hepatitis B: A Real-world, Multicenter Study

Background and Aims

Chronic hepatitis B (CHB) remains a significant global health challenge, and effective antiviral therapies are essential for long-term management. This study aimed to evaluate the real-world effectiveness and safety of tenofovir amibufenamide (TMF) in a cohort of patients with chronic hepatitis B (CHB).

Methods

In this multicenter, prospective, real-world cohort study, 194 CHB patients were recruited from four hospitals between August 2021 and August 2022. Patients were divided into treatment-naïve (TN, n = 123) and treatment-experienced (TE, n = 71) groups. The TN group was further subdivided into TMF (n = 63) and tenofovir disoproxil fumarate (TDF, n = 60) subgroups. In the TE group, patients transitioned from prior antiviral therapies (entecavir or TDF) to TMF after meeting criteria for poor virological response or safety concerns. Treatment response was evaluated in terms of virological effectiveness and alanine transaminase normalization rates. Virological response (VR), ALT normalization rates, renal function markers, and lipid profiles were monitored.

Results

In the TN cohort, VR rates at 24 and 48 weeks were 42.86% and 90.48% for TMF, and 60.00% and 83.33% for TDF. ALT normalization rates at 24 and 48 weeks for TMF were 56.82% and 70.45% (according to AASLD 2018 standards). In the TE group, VR rates at 24 and 48 weeks were 83.1% and 91.55%, respectively. ALT normalization rates were 86.67% and 93.33% (local standards), and 66.67% and 76.67% (AASLD 2018 standards) (z = -2.822, P = 0.005). Additionally, TMF showed improved renal safety over TDF, with no significant differences in lipid concentrations.

Conclusions

TMF is comparable to TDF in terms of CHB treatment effectiveness, with better renal safety and no impact on lipid levels. In TE patients, transitioning to TMF therapy does not affect antiviral treatment outcomes.

Hepatitis B surface antigen: carcinogenesis mechanisms and clinical implications in hepatocellular carcinoma

Liver cancer is the third leading cause of death globally, with hepatitis B virus (HBV) infection being identified as the primary risk factor for its development. The occurrence of HBV-related hepatocellular carcinoma (HCC) is attributed to various mechanisms, such as chronic inflammation and liver cell regeneration induced by the cytotoxic immune response triggered by the virus, abnormal activation of oncogenes arising from HBV DNA insertion mutations, and epigenetic alterations mediated by viral oncoproteins. The envelope protein of the HBV virus, known as hepatitis B surface antigen (HBsAg), is a key indicator of increased risk for developing HCC in HBsAg-positive individuals. The HBsAg seroclearance status is found to be associated with recurrence in HCC patients undergoing hepatectomy. Additional evidence indicates that HBsAg is essential to the entire process of tumor development, from initiation to advancement, and acts as an oncoprotein involved in accelerating tumor progression. This review comprehensively analyzes the extensive effects and internal mechanisms of HBsAg during the various stages of the initiation and progression of HCC. Furthermore, it highlights the importance and potential applications of HBsAg in the realms of HCC early diagnosis and personalized therapeutic interventions. An in-depth understanding of the molecular mechanism of HBsAg in the occurrence and development of HCC is provided, which is expected to develop more precise and efficient strategies for the prevention and management of HCC in the future.

Glycoconjugates of adefovir and tenofovir as asialoglycoprotein-mediated Anti-HBV prodrugs with enhanced liver targeting

Hepatitis B virus (HBV) infection remains a significant global health challenge, often leading to severe liver complications such as cirrhosis and cancer. Current treatments rely heavily on nucleos(t)ide analogues like adefovir and tenofovir due to their potent antiviral effects. However, their clinical utility is limited by insufficient liver targeting, leading to off-target side effects, particularly nephrotoxicity. To improve liver-specific drug delivery and reduce adverse effects, we designed novel liver-targeted prodrugs by conjugating adefovir and tenofovir with N-acetylgalactosamine (GalNAc) and tris-GalNAc ligands, which have high affinity for the asialoglycoprotein receptor (ASGPR) predominantly expressed in hepatocytes. Four prodrugs (A1, A2, T1, and T2) were synthesized and evaluated for cytotoxicity, maximum tolerated dose, anti-HBV activity, metabolic stability, pharmacokinetics, and liver-targeting properties. The prodrugs exhibited low cytotoxicity, robust anti-HBV activity, and enhanced selectivity compared to their parent drugs. Notably, the tris-GalNAc conjugates A2 and T2 demonstrated superior liver targeting, showing a threefold higher concentration in the liver compared to the kidneys, thus minimizing renal exposure. These findings suggest that GalNAc and tris-GalNAc conjugation is a promising strategy for enhancing the therapeutic efficacy and safety of adefovir and tenofovir, with potential for further optimization as liver-targeted anti-HBV prodrugs.

Preparation of tenofovir amibufenamide fumarate spherical particles to improve tableting performance and sticking propensity by designing a spherical crystallization process

Tenofovir amibufenamide fumarate (TMF) is the first oral drug developed in Asia for the treatment of adult patients with chronic viral hepatitis B, however, further applications are limited by poor tableting performance and high sticking propensity. In this work, the spherulitic growth process of TMF has been designed and explored with the help of molecular dynamics simulation and process analysis technologies (ATR-FTIR, FBRM and EasyViewer). The spherical particles with high bulk density, good flowability and uniform particle size distribution are prepared by a simple quenching process. More importantly, experimental results show that spherical particles have higher average tensile strength (100.8% increase), higher plastic deformability and lower amount of punch sticking (87.4% decrease in 30 tablets) compared to the commercial powder products. These contributions not only shed light on the design principle of drug spherulitic growth processes, but also provide guidance for the manufacture of high-quality tablet products.

New conjugates based on N4-hydroxycytidine with more potent antiviral efficacy in vitro than EIDD-2801 against SARS-CoV-2 and other human coronaviruses

The spread of COVID-19 continues due to genetic variation in SARS-CoV-2. Highly mutated variants of SARS-CoV-2 have an increased transmissibility and immune evasion. Due to the emergence of various new variants of the virus, there is an urgent need to develop broadly effective specific drugs for therapeutic strategies for the prevention and treatment of COVID-19. Molnupiravir (EIDD-2801, MK-4482), is an orally bioavailable ribonucleoside analogue of β-D-N4-hydroxycytidine (NHC), has demonstrated efficacy against SARS-CoV-2 and was recently approved for COVID-19 treatment. To improve antiviral potency of NHC, we developed a panel of NHC conjugates with lipophilic vectors and ester derivatives with amino- and carboxylic-acids. Most of the synthesized compounds had comparable or higher (2-20 times) antiviral activity than EIDD-2801, against different lineages of SARS-CoV-2, MERS-CoV, seasonal coronaviruses OC43 and 229E, as well as bovine coronavirus. For further studies, we assessed the most promising compound in terms of activity, simplicity and cost of synthesis - NHC conjugate with phenylpropionic acid (SN_9). SN_9 has shown high efficacy in prophylactic, therapeutic and transmission models of COVID-19 infection in hamsters. Importantly, SN_9 profoundly inhibited virus replication in the lower respiratory tract of hamsters and transgenic mice infected with the Omicron sublineages XBB.1.9.1, XBB.1.16 and EG.5.1.1. These data indicate that SN_9 represents a promising antiviral drug candidate for COVID-19 treatment, and NHC modification strategies deserve further investigation as an approach to develop prodrugs against various coronaviruses.

Studies on the Thermal Decomposition Course of Nitrogen-Rich Heterocyclic Esters as Potential Drug Candidates and Evaluation of Their Thermal Stability and Properties

Drug candidates must undergo thermal evaluation as early as possible in the preclinical phase of drug development because undesirable changes in their structure and physicochemical properties may result in decreased pharmacological activity or enhanced toxicity. Hence, the detailed evaluation of nitrogen-rich heterocyclic esters as potential drug candidates, i.e., imidazolidinoannelated triazinylformic acid ethyl esters 1-3 (where R1 = 4-CH3 or 4-OCH3 or 4-Cl, and R2 = -COOC2H5) and imidazolidinoannelated triazinylacetic acid methyl esters 4-6 (where R1 = 4-CH3 or 4-OCH3 or 4-Cl, and R2 = -CH2COOCH3)-in terms of their melting points, melting enthalpy values, thermal stabilities, pyrolysis, and oxidative decomposition course-has been carried out, using the simultaneous thermal analysis methods (TG/DTG/DSC) coupled with spectroscopic techniques (FTIR and QMS). It was found that the melting process (documented as one sharp peak related to the solid-liquid phase transition) of the investigated esters proceeded without their thermal decomposition. It was confirmed that the melting points of the tested compounds increased in relation to R1 and R2 as follows: 2 (R1 = 4-OCH3; R2 = -COOC2H5) < 6 (R1 = 4-Cl; R2 = -CH2COOCH3) < 5 (R1 = 4-OCH3; R2 = -CH2COOCH3) < 3 (R1 = 4-Cl; R2 = -COOC2H5) < 1 (R1 = 4-CH3; R2 = -COOC2H5) < 4 (R1 = 4-CH3; R2 = -CH2COOCH3). All polynitrogenated heterocyclic esters proved to be thermally stable up to 250 °C in inert and oxidising conditions, although 1-3 were characterised by higher thermal stability compared to 4-6. The results confirmed that both the pyrolysis and the oxidative decomposition of heterocyclic ethyl formates/methyl acetates with para-substitutions at the phenyl moiety proceed according to the radical mechanism. In inert conditions, the pyrolysis process of the studied molecules occurred with the homolytic breaking of the C-C, C-N, and C-O bonds. This led to the emission of alcohol (ethanol in the case of 1-3 or methanol in the case of 4-6), NH3, HCN, HNCO, aldehydes, CO2, CH4, HCl, aromatics, and H2O. In turn, in the presence of air, cleavage of the C-C, C-N, and C-O bonds connected with some oxidation and combustion processes took place. This led to the emission of the corresponding alcohol depending on the analysed class of heterocyclic esters, NH3, HCN, HNCO, aldehydes, N2, NO/NO2, CO, CO2, HCl, aromatics, and H2O. Additionally, after some biological tests, it was proven that all nitrogen-rich heterocyclic esters-as potential drug candidates-are safe for erythrocytes, and some of them are able to protect red blood cells from oxidative stress-induced damage.

Uncovering the mechanism of Tenofovir amibufenamide fumarate punch sticking by combining direct compression experiment and computational simulation

Punch sticking during tablet manufacturing is a prevalent issue for many active pharmaceutical ingredients (APIs) encountered by the pharmaceutical industry. Tenofovir amibufenamide fumarate (TMF), a heavyweight drug for the treatment of hepatitis B, was selected as a model drug due to its tendency to punch sticking during tablet compression. In this study, the cause of sticking was explored by investigating crystal habits, excipients and structure characteristics. The difference in sticking of three crystal habits can be visually represented through direct compression experiments on powdered samples and analysis of crystal surfaces. The excipients play a direct role in decreasing the probability of sticking, and the extent of sticking can be assessed by measuring the tensile strength of the tablet. Additionally, the plasticity index was utilized to theoretically analyze the potential enhancements of four excipients. These experimental results indicate that the block-shaped crystals have superior ability of anti-sticking and that suitable excipients can significantly improve the sticking situation of TMF. Ultimately, the phenomenon of punch sticking was additionally examined through computational calculations, focusing on the mechanical characteristics of TMF molecules and intermolecular interactions. The strategy of combining experiments and simulation calculations has broader significance for the study of drug production.

Influence of Different Ratios of DSPE-PEG2k on Ester Prodrug Self-Assembly Nanoparticles for Cell Migration and Proliferation Suppression

Background

Bufalin (BFL, an active anti-tumor compound derived from toad venom) is limited in its application due to high toxicity and rapid metabolism of the cardiotonic steroid. Ester prodrug self-assembly nanoparticles have shown significant improved effects in addressing the above-mentioned issues.

Methods

An ester bond was formed between linoleic acid and bufalin to synthesize linoleic acid-bufalin prodrug (LeB). The self-assembly nanoparticles (LeB-PSNs) containing different mass ratios of DSPE-PEG2k and prodrug (6:4, 7:3, 8:2, 9:1 and 10:0) were prepared via co-precipitation method and defined as 6:4-PSNs, 7:3-PSNs, 8:2-PSNs, 9:1-PSNs and LeB-PSNs, respectively. Further, the characterization (particle size, zeta potential, surface morphology and stability) of the nanoparticles was carried out. Finally, we evaluated the impact of different ratios of DSPE-PEG2k on the hydrolysis rate, cytotoxicity, cellular uptake, cell migration and proliferation suppression potential of the prodrug nanoparticles.

Results

The linoleic acid-bufalin prodrug (LeB) was successfully synthesized. Upon the addition of DSPE-PEG2k at different weight ratios, both particle size and polydispersity index (PDI) significantly decreased, while the zeta potential increased remarkably. No significant differences in particle size, PDI and Zeta potential were observed among the 9:1, 8:2 and 7:3 PSNs. Notably, the 8:2 (w/w) DSPE-PEG2k nanoparticles exhibited superior stability, hydrolysis and cellular uptake rates, along with efficient cell cytotoxicity, cell migration and proliferation suppression.

Conclusion

These findings indicate that DSPE-PEG2k could improve the performance of BFL prodrug nanoparticles, namely enhancing stability and achieving adaptive drug release by modulating the hydrolysis rate of esterase. This study therefore provides more opportunities for the development of BFL application.

Development of tenofovir monobenzyl ester phosphonoamidate prodrugs with improved anti-hepatitis B virus activity and intrahepatic tenofovir enrichment

Various tenofovir (TFV) prodrugs have been developed by introducing masking groups to the hydroxyls of the monophosphonate group to enhance intestinal absorption efficiency and therapeutic effects. However, the reported TFV prodrugs have drawbacks such as low bioavailability, systemic toxicity caused by their breakdown in non-targeted tissues, and potential low intracellular conversion efficiency. In the present study, we developed a class of TFV monobenzyl ester phosphonoamidate prodrugs without substitutions on the benzene ring. Compared with previous TFV prodrugs, compounds 3a and 3b developed in the present study showed higher anti-hepatitis B virus activity, stronger stability and higher levels of intrahepatic enrichment of the metabolic product (TFV), indicating the potential of these compounds as novel prodrugs with high efficiency and low systemic toxicity for the treatment of hepatitis B.

Tenofovir amibufenamide vs tenofovir alafenamide for treating chronic hepatitis B: A real-world study

BACKGROUND

The efficacy and safety profile of tenofovir amibufenamide (TMF) in chronic hepatitis B (CHB) patients is not well-established.

AIM

To compare the efficacy and safety of TMF and tenofovir alafenamide (TAF) over a 48-wk period in patients with CHB.

METHODS

A total of 215 subjects meeting the inclusion criteria were enrolled and divided into two groups: TMF group (n = 106) and the TAF group (n = 109). The study included a comparison of virological response (VR): Undetectable hepatitis B virus DNA levels, alanine transaminase (ALT) normalization rates, renal function parameters, and blood lipid profiles.

RESULTS

At 24 and 48 wk, VR rates for the TMF group were 53.57% and 78.57%, respectively, compared with 48.31% and 78.65% for the TAF group (P > 0.05). The VR rates were also similar in both groups among patients with low-level viremia, both hepatitis B e antigen (HBeAg)-positive and HBeAg-negative subgroups. The TMF cohort showed ALT normalization and renal safety profiles similar to the TAF group. There was a notable increase in total cholesterol levels in the TAF group (P = 0.045), which was not observed in the TMF group (P > 0.05). In patients with liver cirrhosis, both groups exhibited comparable VR and ALT normalization rates and renal safety profiles. However, the fibrosis 4 score at 48 wk showed a significant reduction in the TAF group as compared to the TMF group within the liver cirrhosis subgroup.

CONCLUSION

Our study found TMF is as effective as TAF in treating CHB and has a comparable safety profile. However, TAF may be associated with worsening lipid profiles.

Effect of Food on the Pharmacokinetics of Tenofovir Amibufenamide: A Phase I, Randomized, Open-Label, Two-Period Crossover Trial in Healthy Adult Subjects

Purpose

Tenofovir amibufenamide (TMF) is a novel nucleotide reverse transcriptase inhibitor. The aim of this study was to investigate the effect of food on the single-dose pharmacokinetic properties of TMF.

Patients and Methods

In this open-label, randomized, crossover study, after an overnight fast, eligible subjects received a single 25 mg dose of TMF tablet, either under fasted conditions or following consumption of a high-fat, high-calorie meal, followed by a two-week washout period. Blood samples were collected until 144 h after administration. TMF and its metabolite, tenofovir (TFV), were analyzed using validated liquid chromatography-tandem mass spectrometry methods. The geometric mean ratio (GMR) and the corresponding 90% confidence interval (CI) values of AUC0-t, AUC0-∞, and Cmax were acquired for analysis. The absence of an effect of food was indicated if the 90% CI values were within the predefined equivalence limits of 80%-125%. Safety and tolerability were also assessed.

Results

For TMF, adjusted GMR (90% CI) values for the fed versus fasted states were 150.28% (125.36%-180.16%), 158.24% (130.42%-192.00%), and 57.65% (45.68%-72.76%) for AUC0-t, AUC0-∞, and Cmax, respectively. For TFV, the GMR (90% CI) of Cmax was 82.00% (74.30%-90.49%) after administration under fed conditions, slightly outside the bioequivalence boundary of 80%-125%, while the corresponding values for AUC0-t and AUC0-∞ were within range. The absorption of TMF was delayed by food, with median Tmax values of 0.33 and 1.00 h in fasted and fed conditions, respectively. The adverse events observed in subjects were all mild.

Conclusion

Our results demonstrated that TMF tablets were well-tolerated in healthy volunteers. When TMF tablets were taken with food, Tmax was delayed and exposures of TMF and TFV were higher than under fasted conditions. The modest changes observed are not considered clinically relevant, so TMF can be taken with or without food.

The Expectation and Reality of the HepG2 Core Metabolic Profile

To represent the composition of small molecules circulating in HepG2 cells and the formation of the "core" of characteristic metabolites that often attract researchers' attention, we conducted a meta-analysis of 56 datasets obtained through metabolomic profiling via mass spectrometry and NMR. We highlighted the 288 most commonly studied compounds of diverse chemical nature and analyzed metabolic processes involving these small molecules. Building a complete map of the metabolome of a cell, which encompasses the diversity of possible impacts on it, is a severe challenge for the scientific community, which is faced not only with natural limitations of experimental technologies, but also with the absence of transparent and widely accepted standards for processing and presenting the obtained metabolomic data. Formulating our research design, we aimed to reveal metabolites crucial to the Hepg2 cell line, regardless of all chemical and/or physical impact factors. Unfortunately, the existing paradigm of data policy leads to a streetlight effect. When analyzing and reporting only target metabolites of interest, the community ignores the changes in the metabolomic landscape that hide many molecular secrets.

96-Week Treatment of Tenofovir Amibufenamide and Tenofovir Disoproxil Fumarate in Chronic Hepatitis B Patients

Background and Aims

Tenofovir amibufenamide (TMF) is a novel phosphoramidated prodrug of tenofovir with noninferior efficacy and better bone and renal safety to tenofovir disoproxil fumarate (TDF) in 48 weeks of treatment. Here, we update 96-week comparison results.

Methods

Patients with chronic hepatitis B were assigned (2:1) to receive either 25 mg TMF or 300 mg TDF with matching placebo for 96 weeks. The virological suppression was defined as HBV DNA levels <20 IU/mL at week 96. Safety was evaluated thoroughly with focusing on bone, renal, and metabolic parameters.

Results

Virological suppression rates at week 96 were similar between TMF and TDF group in both HBeAg-positive and HBeAg-negative populations. Noninferior efficacy was maintained in the pooled population, while it was first achieved in patients with HBV DNA ≥7 or 8 log10 IU/mL at baseline. Non-indexed estimated glomerular filtration rate for renal safety assessment was adopted, while a smaller decline of which was seen in the TMF group than in the TDF group (p=0.01). For bone mineral density, patients receiving TMF displayed significantly lower reduction levels in the densities of spine, hip, and femur neck at week 96 than those receiving TDF. In addition, the lipid parameters were stable after week 48 in all groups while weight change still showed the opposite trend.

Conclusions

TMF maintained similar efficacy at week 96 compared with TDF with continued superior bone and renal safety profiles (NCT03903796).

Chewing the fat: How lipidomics is changing our understanding of human health and disease in 2022

Lipids are biological molecules that play vital roles in all living organisms. They perform many cellular functions, such as 1) forming cellular and subcellular membranes, 2) storing and using energy, and 3) serving as chemical messengers during intra- and inter-cellular signal transduction. The large-scale study of the pathways and networks of cellular lipids in biological systems is called "lipidomics" and is one of the fastest-growing omics technologies of the last two decades. With state-of-the-art mass spectrometry instrumentation and sophisticated data handling, clinical studies show how human lipid composition changes in health and disease, thereby making it a valuable medium to collect for clinical applications, such as disease diagnostics, therapeutic decision-making, and drug development. This review gives a comprehensive overview of current workflows used in clinical research, from sample collection and preparation to data and clinical interpretations. This is followed by an appraisal of applications in 2022 and a perspective on the exciting future of clinical lipidomics.