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Entecavir safety and effectiveness in a national cohort of treatment-naïve chronic hepatitis B patients in the US – the ENUMERATE study
J. Ahn1,*, H. M. Lee2, J. K. Lim3, C. Q. Pan4, M. H. Nguyen5, W. Ray Kim5, A. Mannalithara5, H. Trinh6, D. Chu7, T. Tran8, A. Min9, S. Do10, H. Te11, K. R. Reddy12 andA. S. Lok13
Article first published online: 28 OCT 2015
DOI: 10.1111/apt.13440
© 2015 John Wiley & Sons Ltd
Issue
Alimentary Pharmacology & Therapeutics
Alimentary Pharmacology & Therapeutics
Volume 43, Issue 1, pages 134–144, January 2016
Article has an altmetric score of 1
1 Division of Gastroenterology & Hepatology, Oregon Health & Science University, Portland, OR, USA
2 Gastroenterology/Hepatology Division, Tufts Medical Center, Boston, MA, USA
3 Digestive Diseases, Yale University, New Haven, CT, USA
4 Department of Medicine, NYU Langone, New York, NY, USA
5 Division of Gastroenterology & Hepatology, Stanford University, Stanford, CA, USA
6 San Jose Gastroenterology, San Jose, CA, USA
7 Albert Einstein College of Medicine, New York, NY, USA
8 Department of Medicine, Cedars Sinai Medical Center, Los Angeles, CA, USA
9 Division of Gastroenterology, Mount Sinai Beth Israel, New York, NY, USA
10 Digestive Health Associates of Texas, Plano, TX, USA
11 Digestive Disease Center, University of Chicago, Chicago, IL, USA
12 Division of Gastroenterology and Hepatology, University of Pennsylvania, Philadelphia, PA, USA
13 Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, MI, USA
* Correspondence to:
Dr Joseph Ahn, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, L-461, Portland, OR 97239, USA.
E-mail: [email protected]
This article was accepted for publication after full peer-review.
Summary
Background
Entecavir (ETV) has been shown to be safe and efficacious in randomised controlled trials in highly selected patients with hepatitis B virus (HBV) infection.
Aim
To determine the safety and effectiveness of ETV in ‘real-world’ HBV patients in the United States (US).
Methods
Treatment-naïve HBV patients ≥18 years old who received ETV for ≥12 months between 2005 and 2013 were included in a retrospective, cohort study. Rates of ALT normalisation, undetectable HBV DNA, HBeAg and HBsAg loss/seroconversion, adverse events (AE) and clinical outcomes were evaluated.
Results
Of 841 patients, 658 [65% male, 83% Asian; median age 47 years] met the inclusion criteria. 36% were HBeAg+ and 9.3% cirrhotic. 89% had abnormal ALT. Baseline median HBV DNA was 5.8 log 10 IU/mL. Median duration of ETV treatment was 4 years. Rates of ALT normalisation at 1, 3 and 5 years were 37.2%, 48.7% and 56.2% in HBeAg+ and 39.6%, 46.8% and 55.6% in HBeAg- patients. HBV DNA was undetectable at 1, 3 and 5 years in 34.6%, 64.7% and 84.6% in HBeAg+ patients, and 81.9%, 90.3% and 96.2% in HBeAg patients. Five-year cumulative probability of HBeAg loss and seroconversion was 46% and 33.7% and HBsAg loss was 4.6%. ETV was discontinued due to adverse events in 1.2% of patients. Hepatic decompensation occurred in 0.8%, liver cancer in 2.7% and death in 0.6%.
Conclusion
Entecavir treatment was safe in a large cohort of US patients, but ALT normalisation and hepatitis B virus DNA suppression rates were lower than previously reported in clinical trials.
Introduction
Entecavir (ETV) is a cyclopentyl guanosine analogue, with potent activity against the hepatitis B virus (HBV) DNA polymerase. In 2005, the US Food and Drug Administration (FDA) approved ETV for the treatment of HBV based on randomised controlled trials demonstrating efficacy and safety in hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients that met entry criteria for those trials. These trials showed HBV DNA undetectable rates of 67%, alanine aminotransferase (ALT) normalisation rates of 68%, and HBeAg seroconversion rates of 21% after 1 year of treatment in HBeAg-positive patients.[1] For HBeAg-negative patients, HBV DNA undetectable rates were 90% and ALT normalisation rates were 78% at the end of 1 year of ETV treatment.[2] Subsequent rollover studies provided further follow-up data with undetectable HBV DNA in 94%, ALT normalisation in 80%, an additional HBeAg seroconversion in 23%, and hepatitis B surface antigen (HBsAg) loss in 1.4% of HBeAg-positive patients by year 5.[3] Follow-up data beyond year 1 for HBeAg-negative patients are less clear, as many of these patients had gaps in ETV treatment after year 1.[4] Overall, these studies confirmed long-term safety and a low rate of genotypic anti-viral resistance among nucleoside naïve patients of 1.2% at 6 years.[3, 5, 6]
Due to trial design, the majority of subjects in these Phase III trials had discontinuation or interruption of ETV after the first year.[1-3] Thus, the trial design does not allow assessment of the outcomes of continuous treatment with ETV at the approved dose of 0.5 mg daily. The need for confirmation of the efficacy and safety of continuous ETV treatment at the standard dose, along with growing awareness regarding the distinction between clinical trial efficacy and ‘real-world’ effectiveness led to studies of ETV treatment outcomes in clinical practice.[7-9] There have been several reports, mainly from Asia, showing variable effectiveness among patients treated with ETV in clinical practice attributed to enrolment of a more heterogeneous population as well as the challenges of supporting patients’ compliance to long-term treatment in the ‘real-world’.[10-17] However, there are limited data regarding the effectiveness and safety of ETV in the
US.[18, 19] We aimed to determine the safety and effectiveness of ETV in ‘real-world’ practice settings in the US.
Discussion
ENUMERATE is the largest US ‘real-world’ study of ETV treatment with 658 patients from 26 centers showing that ETV is safe and effective at HBV DNA suppression, ALT normalisation and HBeAg seroconversion. These patients were predominantly foreign-born (61%), Asians (83%), HBeAg negative (64%), with a relatively low baseline ALT (60 U/L) and HBV DNA level (5.8 log 10 IU/mL). Although 61 (9.3%) patients had cirrhosis at baseline, only five patients developed new hepatic decompensation and only two died due to liver-related causes during a median follow-up of 4 years. Eighteen patients were diagnosed with HCC including 10 who did not have cirrhosis at baseline. As liver biopsies or noninvasive assessments of cirrhosis were not routinely performed at the start of treatment, it is possible that some of these 10 patients may have had compensated cirrhosis that was not recognised. Given the small number of HCC cases, no clear relationship between HBV DNA suppression and the diagnosis of HCC can be concluded although it is of interest that undetectable HBV DNA was not protective against the subsequent development of HCC.
ALT normalisation rates at 1 year were 65.9% for HBeAg-positive and 72.8% for HBeAg-negative patients, similar to that reported in Phase III studies of 68% and 78%, respectively [1, 2] when a traditional cut-off of 40 U/L was used to define ‘normal” ALT, but significantly lower, 37.2% for HBeAg-positive patients and 39.6% for HBeAg-negative patients, when cut-offs of 30 U/L for men and 19 U/L for women were used. The possibility that concomitant liver disease such as alcoholic or nonalcoholic fatty liver disease, hepatitis C or hepatitis D could have contributed to the lower ALT normalisation rates cannot be excluded as the study design did not systematically record alcohol use or require baseline viral hepatitis C, hepatitis D or HIV testing or protocol liver biopsies. Undetectable HBV DNA rates at 1 year were lower in our study, 34.6% for HBeAg-positive and 81.9% for HBeAg-negative patients compared to 67% and 90%, respectively in Phase III trials. HBeAg seroconversion rate at 1 year was also lower in our study, 8.9% compared to 21% in the Phase III trial. These lower rates of response may reflect the difference between clinical trials that enrolled selected patients who were provided free medications and monitored closely and effectiveness observations in “real-world” settings enroling a more heterogeneous, potentially less-adherent patient pool with a wider possible range of comorbidities and demographics.
Similar to the Phase III trials, serious adverse events were rare and only eight (1.2%) patients required dose reduction or treatment discontinuation due to adverse events. However, overall changes in dose and treatment discontinuations were common. Of note, 8.1% of patients had increase in dose of ETV from 0.5 to 1.0 mg/day, mostly due to persis'tent viraemia. Virological breakthroughs were observed in only four (0.6%) patients though none were tested for genotypic resistance. Treatment was switched to tenofovir in two patients and ETV dose was increased in the other two patients.
ETV-related lactic acidosis was reported in five patients with decompensated cirrhosis but lactic acidosis was not observed in two prospective studies of ETV in patients with decompensated cirrhosis.[22-25] Two patients in our study who did not have baseline cirrhosis and did not progress to hepatic decompensation, developed nonfatal lactic acidosis. Both had ETV dose increase to 1.0 mg/day and were ambulatory patients with normal creatinine and bilirubin at the time of presentation with lactic acidosis. Neither required hospital admission. Both patients had no recurrence of symptoms after discontinuation of ETV and substitution with another anti-viral agent.
Results from other ‘real-world’ cohorts with chronic HBV who received ETV treatment are summarised in Table 3. Most of these were retrospective, single center studies with small sample size and short duration of follow-up, and variable response rates. The largest study to date was a subgroup analysis of 1663 (29% HBeAg-negative) Chinese patients showing a 1-year rate of undetectable HBV DNA of 60%, ALT normalisation of 87% and HBeAg seroconversion rate of 15% in HBV treatment-naïve patients; there were no significant adverse events.[12] Several multi-center studies from Europe reported similar results.[26, 27] An Italian multicenter study of 418 patients (83% HBeAg-negative, 49% cirrhotic) found that by year 5, 100% of both HBeAg-positive and HBeAg-negative patients had undetectable HBV DNA, 52% had HBeAg seroconversion and 33% had HBsAg loss.[28] The high rate of HBsAg loss in this study has not been observed in other studies. We observed lower rates of ALT normalisation when using the more stringent normal ALT cut-off of 30 for men and 19 for women, and undetectable HBV DNA compared to other ‘real-world’ studies. Our patients were predominantly Asian but our response rates remained lower even when compared to other studies from Asia.
The limitations of this study are inherent in its retrospective study design. The lack of a standardised monitoring protocol may have led to underreporting of adverse events or clinical outcomes. Laboratory tests were performed locally, which could have influenced our assessment of virological response. Nevertheless, the lower limits of detection of HBV DNA assays were fairly similar throughout the sites as all sites used PCR assays with detection limits between 10 and 400 IU/mL. The types and frequency of other laboratory tests varied widely across sites, and contributed to the exclusion of 166 patients due to incomplete baseline laboratory data. Our study included both university and community sites, and therefore reflects inherent ‘real-world’ variation in practice patterns, which differ significantly from standardised clinical trial protocols.
The potential weaknesses of the study such as allowing inclusion of a more heterogeneous pool of patients who would not qualify for Phase III studies e.g. patients who had normal ALT or low HBV DNA at baseline or those who were initiated on a higher ETV dose of 1.0 mg daily can be its strength as it can better reflect the ‘real-world’ practice of HBV treatment. The strengths of this study are its robust sample size, diverse mix of patients from university and community settings from different geographical regions of the US, and long-term follow-up of the cohort. We observed a high rate of treatment discontinuation, which did not appear to be attributable to treatment failure or provider recommendation, and likely reflect ‘real-world’ challenges in maintaining patients on long-term HBV treatment.
In summary, our study of a large cohort of ‘real-world’ patients who received ETV for chronic hepatitis B in the US demonstrated safety and long-term effectiveness despite a heterogeneous patient population and challenges in ensuring adherence to ETV and follow-up in clinical practice.
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