Effectiveness and safety of tenofovir amibufenamide in the treatment of chronic hepatitis B patients with low-level viremia: a retrospective real-world study

Abstract

Background

Tenofovir amibufenamide (TMF) and tenofovir alafenamide (TAF) are considered efficacious and safe nucleoside/nucleotide analogs (NAs) for patients with chronic hepatitis B (CHB). However, real-world data on TMF for CHB patients with low-level viremia (LLV) remain scarce. This study investigated the real-world effectiveness and safety of TMF combined with entecavir (ETV) in the treatment of CHB patients with LLV, and compared the efficacy and safety of TMF combined with ETV and tenofovir alafenamide (TAF) combined with ETV in the treatment of CHB patients with LLV.

Methods

This retrospective real-world study included CHB patients with LLV who received treatment with either TMF combined with ETV or TAF combined with ETV. After the 48-week follow-up, this study evaluated the differences between the two groups in terms of virological response rate (VR rate), ALT normalization rate, HBsAg and HBeAg seroclearance rate, liver fibrosis assessment, and safety endpoints (renal function and blood lipids).

Results

A total of 258 patients were enrolled: 123 in the experimental group (TMF combined with ETV) and 135 in the control group (TAF combined with ETV). The levels of HBV DNA and AST in both groups were significantly lower than the baseline levels after 48-week treatment period (P < 0.05). The VR rate at week 48 was 79.67% in the experimental group, while that in the control group was 72.59%, and there was no statistically significant difference between the two groups (P = 0.184). With respect to the ALT normalization rate, HBsAg seroclearance rate, HBeAg seroclearance rate and liver transient elastography (TE) results, no statistically significant differences were detected between the two groups (P > 0.05). Similarly, for the safety endpoints, including serum creatinine (Cr), glomerular filtration rate (eGFR), triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels, none of these indicators significantly differed between the two groups.

Conclusion

TMF combined with ETV was found to be effective in CHB patients with LLV and appeared to have a favorable safety profile within the limitations of the available data. It exhibits robust antiviral activity and can improve the liver function of patients.

Background

Persistent hepatitis B virus (HBV) infection is a primary etiological factor in the development of liver cirrhosis and hepatocellular carcinoma (HCC) [1]. The long-term therapeutic objective for HBV-infected patients is to maximize the long-term suppression of HBV replication, thereby minimizing the risk of disease-related morbidity and mortality [2]. Nucleoside/nucleotide analogs (NAs) represent the first-line treatment for chronic hepatitis B (CHB) [2]. Although long-term antiviral treatment, CHB patients can achieve sustained virological response (SVR), but approximately 20% to 40% of CHB patients may still experience persistent low-level viremia (LLV) [2–4], defined as the serum HBV DNA level remaining continuously or intermittently below 2000 IU/mL [2, 3]. Numerous studies have demonstrated that LLV is an independent risk factor for the progression of liver fibrosis and the occurrence of HCC [2, 4, 5], and LLV is associated with an accelerated time to tumor recurrence [6]. As a result, managing LLV is still a difficult and common clinical problem in the treatment of CHB. Effective therapeutic intervention for CHB patients with LLV is essential for enhancing long-term prognosis, as sustained viral suppression markedly decreases mortality from HCC and other liver-related diseases [7].

Current international guidelines generally recommend switching to, or combining with, antiviral agents possessing greater potency and a higher genetic barrier to resistance for the management of LLV [2, 3]. These agents include entecavir (ETV), tenofovir alafenamide (TAF), tenofovir disoproxil fumarate (TDF) or tenofovir amibufenamide (TMF). TMF is a Category 1 innovative drug independently developed in China. In terms of the selection of combined treatment strategies, clinical research data for TMF combined with ETV are lacking [2]. Moreover, direct comparative studies evaluating whether TMF combined with ETV or TAF combined with ETV confers a therapeutic advantage are currently lacking.

Consequently, this study aimed to investigate the efficacy and safety of TMF combined with ETV in treating CHB patients with LLV in a real-world setting, and to compare the outcomes with those of TAF combined with ETV.

Materials and methods

Patients

This single-center, retrospective, observational study included patients treated with TMF combined with ETV or TAF combined with ETV in our hospital between January 2022 and July 2025.

Patients who met the diagnostic and antiviral treatment criteria were included. The inclusion criteria were as follows: (1) CHB patients with LLV who met the diagnostic criteria of the Chinese Medical Association’s Guidelines for the Prevention and Treatment of Chronic Hepatitis B (2022 edition) [2]; (2) aged between 18 and 65 years; (3) HBsAg positive; (4) treated for at least 48 weeks.

Patients were excluded if they met any of the following conditions: (1) incomplete clinical data; (2) infection with hepatitis A virus (HAV), hepatitis C virus (HCV), hepatitis D virus (HDV), hepatitis E virus (HEV), acquired immune deficiency syndrome (AIDS), drug-induced liver injury (DILI), autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), alcoholic liver disease or liver transplantation; (3) concurrent or prior interferon therapy.

Patients in the experimental group (TMF combined with ETV) received 25 mg TMF orally once daily (Hansoh Pharmaceuticals Co., Ltd., Jiangsu, China) and 0.5 mg ETV orally once daily (Sino-American Shanghai Squibb Pharmaceuticals Ltd., Shanghai, China or Qilu Pharmaceutical Co., Ltd., Shandong, China). Patients in the control group (TAF combined with ETV) received 25 mg TAF orally once daily (Patheon Inc., Ontario, Canada) and 0.5 mg ETV orally once daily (Sino-American Shanghai Squibb Pharmaceuticals Ltd., Shanghai, China or Qilu Pharmaceutical Co., Ltd., Shandong, China). Before switching to the combination regimens, all patients received NAs therapy for 48 weeks or longer. ETV manufactured by Qilu Pharmaceutical Co., Ltd. passed the Consistency Evaluation of Quality and Efficacy of Generic Drugs in China.

The study adhered to the Declaration of Helsinki and was approved by the Ethics Committee of Beijing Youan Hospital, Capital Medical University. Approval number: LL-2024-137-K.

Endpoints

The primary effectiveness endpoint was virological response (VR) at week 48, defined as serum HBV DNA level < 10 IU/mL (lower limit of detection: 10 IU/mL) at week 48. Secondary effectiveness endpoints included ALT (alanine aminotransferase) normalization rate (male ALT < 50 U/L, female ALT < 40 U/L), HBsAg and HBeAg seroclearance rate, and liver transient elastography (TE, FibroScan) at week 48. Safety endpoints included changes in renal function and blood lipids.

Statistical analysis

Statistical analyses were performed using IBM SPSS version 26.0.

Continuous variables with a normal distribution are expressed as the mean ± standard deviation (SD) and were compared with a t-test. Non-normally distributed data are represented as medians with interquartile ranges (IQRs), and were compared by the Mann-Whitney U test. Categorical variables are expressed as numbers (percentages) and were compared using the chi-square test or Fisher’s exact test. A P -value < 0.05 was considered statistically significant.

Results

Baseline characteristics

A total of 258 patients were enrolled, including 123 in the experimental group and 135 in the control group (Fig. 1). The baseline characteristics of the patients in this study are shown in (Table 1). Both groups had a high proportion of male participants. The mean age was 42.46 ± 6.70 years in the experimental group and 43.84 ± 7.74 years in the control group. In the experimental group, the positive rate of HBeAg was 74.80%, and the proportion of patients with normal ALT was 81.30%. In the control group, the positive rate of HBeAg was 79.26%, and the percentage of patients whose ALT was within the normal range was 81.48%. Liver fibrosis was assessed using TE (FibroScan). Regarding liver fibrosis stages at baseline, the distribution was similar between the two groups. In the experimental group, 53.66%, 18.70%, 9.76%, and 18.88% of patients were classified as stage F0–1, F2, F3, and F4, respectively, compared to 55.56%, 17.04%, 8.89%, and 18.51% in the control group. Statistical analysis revealed no significant differences in baseline characteristics between the groups (P > 0.05).

Fig. 1.

Flowchart of the study population

Table 1.

Patient baseline data

	experimental group	control group	statistic	P-value
Gender, n			χ2  = 1.324	0.250
Male patients	89	106
Female patients	34	29
Age (years)	42.46 ± 6.70	43.84 ± 7.74	t = 1.525	0.128
Weight (kg)	67.49 ± 8.74	68.09 ± 9.73	t = 0.520	0.603
HBsAg(IU/mL)	3067(1146, 6443)	3704(1334, 9791)	Z = 1.078	0.281
HBeAg, n			χ2 = 0.727	0.394
Positive	92	107
Negative	31	28
History of antiviral treatment, n			χ2 = 1.322	0.250
monotherapy	90	107
combination therapy	33	28
HBV DNA(IU/mL)	66(32, 211)	80(24, 312)	Z = 0.486	0.627
ALT(U/L)	26(19, 35)	29(19, 40)	Z = 1.237	0.216
AST(U/L)	25(22, 31)	26(21, 36)	Z = 0.375	0.708
TBIL(µmol/L)	15.0(12.0, 23.3)	15.9(11.9, 20.7)	Z = 0.041	0.967
Cr(µmol/L)	64(53, 73)	66(58, 77)	Z = 1.612	0.107
eGFR(mL/min/1.72m2)	113.0(106.4, 115.9)	110.8(101.1, 117.4)	Z = 1.132	0.258
TG(mmol/L)	1.06(0.65, 1.49)	1.19(0.83, 1.43)	Z = 1.940	0.052
TC(mmol/L)	4.47(3.75, 4.87)	4.55(4.07, 5.20)	Z = 1.862	0.063
HDL(mmol/L)	1.18(1.00, 1.42)	1.13(0.93, 1.41)	Z = 1.960	0.051
LDL(mmol/L)	2.68(1.96, 3.33)	2.94(2.24, 3.08)	Z = 1.108	0.268
TE (FibroScan)
F0-1	66	75	χ2 = 0.208	0.976
F2	23	23
F3	12	12
F4	22	25

Abbreviations: *TBIL total bilirubin, AST aspartate aminotransferase, ALT alanine aminotransferase, Cr creatinine, eGFR estimated glomerular filtration rate, TG triglyceride, TC total cholesterol, HDL high-density lipoprotein, LDL low-density lipoprotein, TE liver transient elastography, F0-1 indicates no or mild liver fibrosis, F2 indicates moderate liver fibrosis, F3 indicates severe liver fibrosis, and F4 indicates liver cirrhosis

Effectiveness of TMF combined with ETV

Laboratory examination

As presented in Table 2, after 48-week treatment with TMF combined with ETV, HBV DNA and AST (aspartate aminotransferase) levels of patients in the experimental group significantly decreased from baseline (P < 0.05). In contrast, there were no significant changes in ALT or total bilirubin (TBIL) levels compared with those at baseline within this group.

Table 2.

Laboratory test results before and after treatment

	experimental group				control group				P - value*
	baseline	week 48	statistic	P - value	baseline	week 48	statistic	P - value
HBV DNA(IU/mL)	66(32, 211)	0(0, 0)	Z = 12.611	< 0.001	80(24, 312)	0(0, 28)	Z = 11.102	< 0.001	0.069
HBsAg(IU/mL)	3067(1146, 6443)	2426(806, 5394)	Z = 1.117	0.264	3704(1334, 9791)	2541(996, 6952)	Z = 1.667	0.095	0.706
HBeAg			χ2 = 0.732	0.392			χ2 = 1.014	0.314	0.457
Positive	92	86			107	100
Negative	31	37			28	35
ALT(U/L)	26(19, 35)	25(16, 32)	Z = 1.818	0.069	29(19, 40)	26(18, 35)	Z = 1.730	0.084	0.151
AST(U/L)	25(22, 31)	19(16, 22)	Z = 3.440	0.001	26(21, 36)	23(19, 35)	Z = 3.590	< 0.001	0.615
TBIL(µmol/L)	15.0(12.0, 23.3)	16.1(12.0, 19.9)	Z = 0.146	0.884	15.9(11.9, 20.7)	16.8(14.3, 21.5)	Z = 1.287	0.198	0.161
Cr(µmol/L)	64(53, 73)	64.0(55, 71)	Z = 0.179	0.858	66(58, 77)	68(57, 78)	Z = 0.518	0.605	0.054
eGFR(mL/min/1.72m2)	113.0(106.4, 115.9)	110.9(103.1, 114.5)	Z = 1.803	0.071	110.8(101.1, 117.4)	107.5(102.4, 113.1)	Z = 1.385	0.166	0.082
TG(mmol/L)	1.06(0.65, 1.49)	1.07(0.90, 1.58)	Z = 1.662	0.096	1.19(0.83, 1.43)	1.07(0.78, 1.65)	Z = 0.671	0.502	0.420
TC(mmol/L)	4.47(3.75, 4.87)	4.37(3.98, 4.84)	Z = 0.720	0.471	4.55(4.07, 5.20)	4.53(3.75, 5.14)	Z = 0.199	0.843	0.411
HDL(mmol/L)	1.18(1.00, 1.42)	1.10(0.89, 1.44)	Z = 1.752	0.080	1.13(0.93, 1.41)	1.09(0.91, 1.39)	Z = 0.612	0.540	0.926
LDL(mmol/L)	2.68(1.96, 3.33)	2.66(2.16, 3.17)	Z = 0.915	0.360	2.94(2.24, 3.08)	2.71(2.27, 3.37)	Z = 0.176	0.861	0.403
TE (FibroScan)
F0-1	66	66	χ2 = 0.062	0.996	75	74	χ2 = 0.047	0.997	0.988
F2	23	22			23	23
F3	12	13			12	13
F4	22	22			25	25

*Comparison of treatment results between the experimental group and control group at week 48

Virological response

In the experimental cohort, the median baseline HBV DNA level was 66 (32, 211) IU/mL. After the 48-week treatment with TMF combined with ETV, a significant reduction in HBV DNA was observed, with a median value of 0 (0, 0) IU/mL (P < 0.001). VR was achieved in 98 patients (79.67%) (Table 2; Fig. 1).

HBeAg and HBsAg

After the 48-week treatment with TMF combined with ETV, the median HBsAg level in the experimental group decreased from 3067 (1146, 6443) IU/mL to 2426 (806, 5394) IU/mL; however, the difference was not statistically significant (P = 0.264). None of the patients in the experimental group achieved HBsAg clearance. At baseline, 92 HBeAg-positive patients were included in the experimental group. After the 48-week treatment, 6 patients (6.52%) achieved HBeAg clearance. (Table 2 ; Fig. 1).

ALT and AST

The median baseline ALT level in the experimental group was 26 (19, 35) U/L, which did not differ significantly from the median ALT level of 25 (16, 32) U/L observed after the 48-week treatment with TMF combined with ETV (P = 0.069). Among patients with elevated ALT level at baseline, the ALT normalization rate after the 48-week treatment was 65.22% (Table 2; Fig. 1).

The median baseline AST level in the experimental group was 25 (22, 31) U/L, and after the 48-week treatment with TMF combined with ETV the median AST level was 19 (16, 22) U/L, which was significantly different (P = 0.001) (Table 2).

TE (FibroScan)

The TE test we use is FibroScan. In the experimental group, only one patient showed a change in fibrosis stage (from F2 to F3) after the 48-week treatment with TMF combined with ETV, while all the other patients remained unchanged. Comparisons of baseline and week 48 data revealed no statistically significant difference (P > 0.05) (Table 2).

Safety of TMF combined with ETV

Renal function

During the 48-week follow-up period, the median baseline serum creatinine (Cr) level of the experimental group was 64 (53, 73) µmol/L, and the median week 48 Cr level was 64.0 (55, 71) µmol/L. The median baseline glomerular filtration rate (eGFR) level of the experimental group patients was 113.0 (106.4, 115.9) mL/min/1.72m², and the median week 48 eGFR level was 110.9 (103.1, 114.5) mL/min/1.72m². No statistically significant changes were observed in either indicator following treatment in the experimental group (P > 0.05).

Blood lipids

In our study, blood lipids included triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL), and low-density lipoprotein (LDL). At baseline, the median TG level in the experimental group was 1.06 (0.65, 1.49) mmol/L, which was 1.07 (0.90, 1.58) mmol/L after the 48-week treatment with TMF combined with ETV. The median TC level was 4.47 (3.75, 4.87) mmol/L at baseline and 4.37(3.98, 4.84) mmol/L after the 48-week treatment with TMF combined with ETV. For HDL, the median baseline level was 1.18 (1.00, 1.42) mmol/L, and it was 1.10 (0.89, 1.44) mmol/L at week 48. The median LDL level was 2.68 (1.96, 3.33) mmol/L at baseline, and 2.66 (2.16, 3.17) mmol/L at week 48. No statistically significant differences were observed in any blood lipids when baseline levels were compared to those at week 48 in the experimental group (P = 0.096, 0.471, 0.080, 0.360) (Table 2).

Effectiveness and safety of TMF combined with ETV vs. TAF combined with ETV

Comparison of effectiveness

No significant differences were observed between the two groups in terms of baseline laboratory indices, including the levels of HBV DNA, HBsAg, HBeAg, ALT, AST, TBIL or TE (P > 0.05). After the 48-week treatment, comparisons of these laboratory indices revealed no statistically significant differences between the experimental and control groups (P > 0.05) (Table 2).

At week 48, the VR rate was 79.67% in the experimental group and 72.59% in the control group. Although the VR rate in the experimental group was slightly higher than that in the control group, the difference was not statistically significant (P = 0.184). Regarding ALT normalization, the proportion of patients with normal ALT levels increased from 81.30% to 93.50% in the experimental group and from 81.48% to 93.33% in the control group. The ALT normalization rates were 65.22% in the experimental group and 64.00% in the control group. There was no statistically significant difference in the ALT normalization rate between the two groups at week 48 (P > 0.05) (Table 2; Fig. 2).

Fig. 2.

Antiviral efficacy of TMF combined with ETV and TAF combined with ETV in the experimental group and control group at week 48

After the 48-week treatment, 53.65% of patients in the experimental group were classified as stage F0–1, compared with 54.81% in the control group. The proportions for stage F2 were 17.89% and 17.04%, respectively. For stage F3, the rates were 10.57% in the experimental group versus 9.63% in the control group. For stage F4, they were 17.89% versus 18.52%. In the control group, 2 patients showed changes in fibrosis stage: one progressed from F0–1 to F2, and the other progressed from F2 to F3. All the other patients remained stable. No statistically significant difference was observed in the distribution of fibrosis stages between the experimental and control groups (P > 0.05) (Table 2).

With respect to the baseline data, the experimental group included 92 HBeAg-positive patients, compared with 107 patients in the control group. After the 48-week treatment, 6 patients in the experimental group and 7 patients in the control group achieved HBeAg clearance. The HBeAg clearance rates were 6.52% in the experimental group and 6.54% in the control group. There was no statistically significant difference between the two groups (P > 0.05).

After the 48-week treatment, the median HBsAg level in the experimental group decreased from 3704 (1334, 9791) IU/mL to 2426 (806, 5394) IU/mL, while that in the control group decreased from 3067 (1146, 6443) IU/mL to 2426 (806, 5394) IU/mL. Compared with the baseline level, both groups showed a slight decrease in HBsAg levels, however, no statistically significant differences were observed either between groups or within groups (P > 0.05). Moreover, no patients in either group achieved HBsAg clearance.

Comparison of safety

Compared with the baseline data, the median change in Cr was 0 (-5, 3) µmol/L at week 48, and the median change in eGFR was 0.6 (-4.2, 1.7) mL/min/1.72m² in the experimental group at week 48. In the control group, compared to baseline the median change in Cr was 0 (-3, 4) µmol/L, and the median change in eGFR was − 1.20 (-5.5, 2.4) mL/min/1.72m². There was no significant change in renal function for either group compared to baseline (P > 0.05). Regarding blood lipids results, there were no significant changes in TG, TC, HDL, or LDL compared to baseline in both groups (P > 0.05). When comparing the experimental group and the control group, there were no statistically significant differences in renal function and blood lipid levels both at either baseline or week 48 (P > 0.05) (Fig. 3).

Fig. 3.

Changes in renal and blood lipid safety profiles between patients in the experimental group and control group. Changes in Cr (A), eGFR (B), TG (C), TC (D), HDL (E) and LDL (F) at week 48

Discussion

The relevant guidelines state [2] that TAF, as a prodrug of tenofovir (TFV), is widely used to treat CHB because of its high intracellular concentration and low systemic exposure. The combination regimen of TAF with ETV has demonstrated potent viral suppression and favorable safety profiles in multiple studies [8]. For patients who do not respond adequately to TMF or have LLV, switching to or adding ETV based on the antiviral mechanism of the drug is also a feasible option. However, efficacy data of TMF combined with ETV in real-world settings remain insufficient.

In China, TMF is a Category 1 innovative drug, independently developed antiviral prodrug developed via structural modification of TAF to optimize therapeutic efficacy and safety. By incorporating a methylated phosphoramide ester moiety, TMF undergoes efficient intracellular hydrolysis to release tenofovir (TFV), which improves hepatic targeting, enhancing oral bioavailability, and minimizing systemic exposure to TFV. This targeted delivery mechanism reduces off-target adverse effects, particularly bone mineral density loss and renal tubular dysfunction, which are well-documented limitations of TDF [1]. The results of phase III trials and real-world data confirm that compared with TDF and TAF, TMF does not significantly differ in terms of antiviral efficacy, with superior renal and bone safety profiles, indicating that TMF is a promising therapeutic option for optimizing long-term CHB management [9–11]. A multicenter real-world study [12] indicated that TMF exhibited excellent antiviral efficacy in both treatment-naïve and treatment-experienced patients. In treatment-naïve patients, the virological response rate reached 90.48%, which was comparable to that of patients treated with the TDF regimen (83.33%). In patients with LLV, the rate of HBV DNA negativity with TMF reached 84%, significantly reducing the risks of drug resistance and liver fibrosis, thereby providing an efficient and safe treatment option for this high-risk group. According to the Chinese Medical Association’s Guidelines for the Prevention and Treatment of Chronic Hepatitis B (2022 edition) [2], for CHB patients with detectable HBV DNA (patients with LLV) after the 48-week treatment with ETV, TDF, TAF, or TMF—after excluding poor medication adherence and testing errors—the recommended management strategies are: (a) switching to an alternative NAs (e.g., from ETV to TDF/TAF, or from TDF/TAF to ETV); (b) combination therapy with two NAs; or (c) combination therapy with pegylated interferon (Peg-IFN-α). Some studies have demonstrated that combination therapy with two high-genetic-barrier NAs significantly improves virological response rates at both week 48 and 96 in CHB patients with LLV. However, we believe that combination therapy should be reserved for selected cases in which switching to monotherapy is considered insufficient or inappropriate.

Compared with previous related studies, this research aimed to evaluate and compare the efficacy and safety of TMF combined with ETV and TAF combined with ETV in CHB patients with LLV. This study demonstrated that, following the 48-week treatment, both regimens were highly effective in suppressing HBV replication in CHB patients with LLV, resulting in substantial decreases in HBV DNA levels among all participants. In the experimental group, the VR rate was 79.67%, and in the control group, it was 72.59%. The experimental group had a slightly higher VR rate than the control group, but the difference was not statistically significant. The VR rates in both groups of this study were lower than those reported in Li’s study [11].

The paramount objective in managing CHB is to attain a functional cure, defined by sustained HBsAg loss, although this remains an elusive endpoint with current antiviral treatments. Previous clinical data demonstrate that the median annual reduction in HBsAg levels during ETV monotherapy is approximately 0.125 log10 IU/mL/year [13]. Consistent with these findings, the current study demonstrated only slight decreases in HBsAg levels following the 48-week treatment in both groups, with no patients achieving HBsAg clearance. Furthermore, no statistically significant differences were detected in the HBsAg clearance rates or absolute levels between the two groups at baseline or during the 48-week treatment period. In the phase III trial of TMF, week 48 and 96 HBeAg seroconversion rates were 17.2% and 27.0%, respectively; however, in this study, the corresponding rates were markedly lower, at 6.52% (experimental group) and 6.54% (control group), respectively. These reduced efficacy outcomes correspond with the findings of Li et al. [12] and likely indicate the complex clinical characteristics of our study population, comprising CHB patients with LLV with previous NAs exposure, a subgroup known to exhibit reduced responsiveness to antiviral therapy.

Regarding effectiveness endpoints such as the HBsAg and HBeAg seroclearance rates, no statistically significant differences were observed between the two groups (P > 0.05). These results indicate that, when combined with ETV, TMF and TAF demonstrate similar short-term antiviral effectiveness.

Previous studies have confirmed that TAF has an advantage in terms of the ALT normalization rate. Our study revealed that the ALT normalization rate in the experimental group was 65.22%, which was slightly higher than that in the control group (64.00%), with no significant intergroup difference (P > 0.05). Since all patients in this study had been previously treated, the overall ALT normalization rates were significantly lower than those in previous studies, but this finding was consistent with the ALT normalization rate of treated patients in subgroups of other studies [11, 12]. AST levels in both groups were significantly lower after treatment than at baseline, with statistically significant differences observed within each group (P < 0.05).

However, no statistically significant difference was found between the two groups (P > 0.05). These results suggest that both TMF and TAF are effective at improving liver function in patients.

Multiple clinical meta-analyses have demonstrated that LLV increases the risk of liver cirrhosis and HCC in patients with CHB. A study from Korea [14] reported that the 5-year cumulative incidence of HCC was higher in patients with LLV than in those who achieved complete virologic response (up to 14.3%). Similarly, a Chinese study [15] revealed that, compared with patients with a complete virological response after antiviral therapy, those with LLV had a significantly higher risk of developing end-stage liver disease (decompensated cirrhosis and HCC) at 5 and 10 years (0.77% and 5.52%, respectively). In our study, no statistically significant differences in liver fibrosis stage were observed between the experimental and control groups, whether baseline TE results, week 48 results, or within-group comparisons before and after treatment were performed. It should be emphasized that the 48-week follow-up duration is clinically insufficient to detect appreciable histological regression or significant improvements in liver fibrosis via TE during antiviral therapy. The observation that most patients remained stable in fibrosis stage is therefore an expected outcome of this relatively short observation period, rather than a direct reflection of treatment efficacy. This interpretation is explicitly emphasized to prevent readers from misinterpreting the transient elastography results. Therefore, longer-term follow-up assessments at 96 weeks or beyond will be conducted to more comprehensively evaluate dynamic changes in liver fibrosis in these patients.

In terms of safety, the risk of renal damage and dyslipidemia caused by TFV-class antiviral drugs for treating HBV has become a key focus in clinical research [16]. Therefore, in this study, the safety of TMF was primarily evaluated by monitoring changes in renal function parameters (Cr and eGFR) and lipid metabolism markers (TG, TC, HDL, and LDL) among the enrolled patients. Data from 96-week phase III trials of TMF indicated a slight decrease in the eGFR and an increase in Cr; however, these changes were not statistically significant before and after treatment in the experimental group of this study. Additionally, there were no statistically significant differences in renal function indicators between the two groups following the 48-week treatment. These outcomes are consistent with the renal safety profile described in the prescribing information for TAF and TMF, supporting their positive renal tolerability. Notably, while prior studies have demonstrated that TAF influences certain lipid parameters [16], neither the experimental group nor the control group in this study exhibited significant worsening of TG, TC, HDL, or LDL levels compared with baseline. These results indicate that both TMF and TAF have minimal effects on lipid metabolism. The combination therapy appeared to have a favorable safety profile within the limitations of the available data. These observations align with the safety data of TMF in Asian populations reported by Liu et al. [10], which showed that the TMF-containing regimen did not result in significant changes in renal function or lipid profiles over 48 and 96 weeks.

Strengths and limitations

This real-world retrospective cohort study aimed to compare the efficacy and safety of TMF combined with ETV versus TAF combined with ETV in CHB patients with LLV. This study demonstrated that TMF combined with ETV achieves comparable antiviral efficacy and safety to TAF combined with ETV, with no statistically significant differences between the two regimens. While the study design is not novel and resembles those of existing studies, it specifically targets the under-researched population of CHB patients with LLV, thereby addressing a critical gap in the literature regarding the comparative effectiveness and safety of these two combination therapies. Moreover, this study contributes valuable real-world evidence that complements the limited data from phase III clinical trials and enhances the understanding of TMF-based treatment. Nevertheless, several limitations should be noted. First, the 48-week follow-up period was relatively short, and the study may lack sufficient power to detect subtle differences between treatments and cannot reliably assess long-term outcomes, such as HBsAg seroconversion and liver fibrosis outcomes. Other research has shown that after the treatment plan was adjusted, the patient’s HBV DNA test became negative at week 48. However, during the extended follow-up period of 120 weeks, the levels of indicators such as HBsAg continued to decrease. There were also differences in liver fibrosis indicators among the different groups of patients. These results suggest that long-term follow-up for 96 weeks or longer is highly important for a comprehensive evaluation of therapeutic effects. As a widely used time point in clinical research, week 48 still provides a series of objective indicators with important clinical value. These indicators not only constitute important bases for formulating early treatment strategies, but also have been proven to be surrogate markers for predicting long-term clinical outcomes. Second, this is a single-center retrospective analysis with a relatively small sample size, and the study may be subject to selection bias. Third, approximately 80% of the enrolled patients lacked serum calcium and phosphate measurements at both baseline and week 48. These data were therefore excluded from the safety evaluation. We acknowledge that this constitutes a significant limitation. Without serum calcium and phosphate measurements, we cannot evaluate subclinical tenofovir-associated renal tubule injury, which is an important safety consideration for TMF and TAF therapy. Fourth, biomarkers reflecting bone abnormalities are lacking, as the patient reexamination cycle in the real world is often longer than 48 weeks, making the acquisition of relevant data difficult. Finally, as a retrospective observational cohort study, selection bias is an inherent limitation due to the lack of randomization. Although baseline characteristics were comparable between groups (Table 2) with no statistically significant differences, this does not fully eliminate the risk of selection bias or residual confounding. Given that no PSM or multivariable regression analyses were performed to adjust for baseline confounders, the lack of statistical adjustment may affect the robustness of our results, and the potential effects of unmeasured confounding and selection bias cannot be excluded. Future studies will adopt a prospective design and use methods such as PSM or multivariable regression analysis to strictly control for baseline confounding variables, thereby further verifying the core conclusions of this study and improving the reliability and persuasiveness of the results. Given these constraints, future multicenter, large-scale, prospective randomized controlled trials with prolonged follow-up are warranted to further validate the role of TMF combined with ETV in CHB management and to explore its therapeutic potential in specific subpopulations, including those with liver cirrhosis or elderly patients.

Conclusions

In this 48-week retrospective cohort study, TMF combined with ETV demonstrated favorable anti-HBV efficacy in CHB patients with LLV. The combination therapy appeared to have a favorable safety profile within the limitations of the available data, with no obvious adverse effects on renal function or blood lipids. Compared with TAF combined with ETV, TMF combined with ETV showed no statistically significant differences in either anti-HBV efficacy or safety. However, this study has several limitations, including its single-center design, relatively small sample size, and a follow-up period of only 48 weeks, which may not be sufficient to fully capture long-term outcomes such as HBsAg seroconversion and liver fibrosis progression. Therefore, further multicenter studies with larger cohorts and extended follow-up periods are warranted to confirm these findings.

Abbreviations

TMF

Tenofovir amibufenamide

CHB

chronic hepatitis B

LLV

Low-level viremia

ETV

Entecavir

TAF

Tenofovir alafenamide

Cr

Creatinine

eGFR

Glomerular filtration rate

TG

Triglycerides

TC

Total cholesterol

HDL

High-density lipoprotein

LDL

Low-density lipoprotein

TE

Liver transient elastography

VR

Virologic response

HBV

Hepatitis B virus

HCC

Hepatocellular carcinoma

NAs

Nucleoside/nucleotide analogs

SVR

Sustained virological response

HAV

Hepatitis A virus

HCV

Hepatitis C virus

HDV

Hepatitis D virus

HEV

Hepatitis E virus

AIDS

Acquired immune deficiency syndrome

AIH

Autoimmune hepatitis

PBC

Primary biliary cholangitis

PSC

Primary sclerosing cholangitis

DILI

Drug-induced liver injury

ALT

Alanine aminotransferase

AST

Aspartate aminotransferase

TBIL

Total bilirubin

TFV

Tenofovir

TDF

Tenofovir disoproxil fumarate

Authors' contributions

Conceptualization, W L and XY Q. Methodology, Y Y and XY Q. Software, Y Y and XY Q. Formal Analysis, SB Z. Investigation, Y Y. Data Curation, Y Y and XY Q. Writing – Original Draft Preparation, Y Y and XY Q. Writing – Review & Editing, W L and SB Z.

Funding

The authors declare that no financial support was received for the research and/or publication of this article.

Data availability

All data used in the study are presented in the tables.

Declarations

Ethics approval and consent to participate

The Approval Committee is the Ethics Committee of Beijing You ‘an Hospital, Capital Medical University. Approval number: LL-2024-137-K. According to the requirements of the Guidelines for Ethical Review of Biomedical Research Involving Human Subjects in Healthcare Institutions in Beijing Area issued by the Beijing Municipal Health Commission, retrospective studies that meet the criteria for minimal risk may be exempted from informed consent. The ethics committee review board waived the requirement of written informed consent for participation from the participants or the participants’ legal guardians/next of kin because this is a retrospective study, and the patient data used were formed during the normal diagnosis and treatment of patients, and did not cause any additional harm to patients.

Consent for publication

All authors agree to publication.

Competing interests

The authors declare no competing interests.