Unité d'Hépatologie, Hôpital Cochin, Université Paris Descartes, APHP, INSERM U.1016, Paris, France First Gastroenterology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico Università di Milano, Milan, Italy.
Summary. Entecavir (ETV) and tenofovir disoproxil fumarate (TDF) are potent nucleos(t)ide analogues (NUCs) recommended as first-line monotherapies for chronic hepatitis B. In Phase III trials, ETV and TDF demonstrated superior efficacy, and comparable safety compared with other NUCs. In long-term clinical studies, both drugs achieved virologic response rates of around 95%, with very low rates of resistance development and good safety profiles. Clinical trials are conducted under standardized conditions with strict enrolment criteria that limit the heterogeneity of study populations. 'Real-life' populations tend to be composed of a wider range of patients, often older and with different morbidities, comorbidities that may impact treatment efficacy and co-factors, such as smoking and alcohol intake, which can have a direct impact on disease progression. Real-life studies provide better representations of everyday clinical practice and are important to confirm the results reported in clinical studies and to identify rare or late-emerging adverse events. In five 'real-life' studies of ETV in more than 1000 patients, up to 4 years of treatment resulted in virologic responses in 76-96% of patients. Two real-life studies of TDF reported response rates of 71-92% after up to 21 months of treatment. Low incidences of drug resistance and favourable tolerabilities were reported for both drugs, thus confirming the results from registration trials.