The Impact of Tenofovir Alafenamide on Profiles of Body Weight and Metabolic Features in Chronic Hepatitis B Patients

Currently, three oral nucleoside/tides analogues (NUC), including entecavir(ETV), tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide (TAF), are available as the first line of treatment option for chronic hepatitis B (CHB) in Taiwan. Among them, TDF exhibits a greater decline of cholesterol, High-density lipoprotein(HDL), and low-density lipoprotein (LDL) levels than entecavir, while the impact of such general lipid-lowering effects on the risk of atherosclerotic cardiovascular diseases (ASCVD) remains unclear. For metabolic features, the evidence comes from HIV patients treated with TDF or TAF containing anti-retroviral therapy (ART). In one study revealed that a 0.45 kg/m2 increase of body mass index (BMI) and a 13% of increase in ASCVD risk score after switching from TDF-containing to TAF-containing ART. Weight gain after starting ART has been reported to associate with lower mortality in initial under-weight or normal-weight HIV patients. However, a study compared the efficacy and safety of dolutegravir/TAF/emtricitabine, dolutegravir/TDF/emtricitabine, and EFV/TDF/emtricitabine and revealed that patients receiving TAF and TDF containing regimens significantly increased body weight. The subsequent body composition analysis showed weight gain mainly resulted from increased lean muscle and fat of trunk and limb. A previous study also showed that the ART-associated increase in muscle area, regardless of regimen, is likely a reflection of increased fat within the muscle that may associate with weakness of muscle strength, risk of fall, and a decline of physical activities.

Overall, in HIV-infected patients, TAF-containing regimens had been shown to increase body weight resulting from increased fat and muscle of trunk and limb. However, it remains unknown whether all these findings in HIV infected patients could be similarly observed in CHB patient receiving TAF therapy, which is commonly encountered in Asia-Pacific region. Moreover, the mechanisms underlying these changes are still unclear. The long-term clinical impact of the BW gain and associated metabolic derangement is also unknown.