HBV DNA suppression sustained with switch to tenofovir
medwireNews: Italian research shows that patients with chronic hepatitis B virus (HBV) infection maintain long-term virologic suppression after switching from lamivudine plus adefovir to tenofovir disoproxil fumarate (TDF) monotherapy, with a low rate of adverse events.
During a median 57 months of TDF monotherapy, all 60 patients with lamivudine resistant hepatitis B e antigen (HBeAg)-negative HBV had persistently undetectable levels of HBV DNA with no transient HBV DNA blips observed. Four patients cleared hepatitis B surface antigen, at a median of 16.5 months, and discontinued treatment with no relapse observed up to 43 months later.
Prior to switching to TDF, all of the patients, who had a median age of 58 years and were mostly male (80%), had stable viral suppression during treatment with lamivudine plus adefovir for at least 24 months.
Teresa Santantonio (University of Foggia) and study co-authors report that TDF treatment was well tolerated, with no significant side effects reported in all but one patient, who discontinued TDF after 37 months due to severe arthromyalgia.
The researchers also found that, despite stable virologic suppression for more than 5 years, five cirrhotic patients and one chronic HBV patient developed hepatocellular carcinoma.
No cases of Fanconi syndrome were detected during renal function monitoring and there were no significant changes in median serum creatinine and phosphate levels, or estimated glomerular filtration rate (eGFR) in the majority of cases.
Five patients did, however, require a TDF dose reduction after a median of 53 months, four patients because of a significant eGFR decline (<60 mL/min) and one due to serum phosphate levels falling below 2 mg/dL.
“These findings emphasize the importance of continued close monitoring of renal function in patients treated with TDF, especially if previously exposed to [adefovir],” the researchers remark.
Santantonio and team also note that 10 patients experienced bone mineral density (BMD) loss after 2 years of TDF therapy, which is in agreement with previous reports in patients with HIV, and suggests that “[f]urther studies will be required to confirm whether there is a direct meaningful effect of TDF on BMD loss.”
Writing in Digestive and Liver Disease, Santantonio et al say that simplifying therapy by substituting lamivudine plus adefovir with TDF comes with “remarkable” advantages, including reduced costs, improved adherence, and avoidance of long-term exposure to adefovir, which is more nephrotoxic than TDF.
“In addition, a potential benefit of early switching [from adefovir] to TDF is to avoid the selection of [adefovir-resistant] mutants which might compromise the efficacy of the subsequent TDF rescue therapy,” they conclude.
By Laura Cowen
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