BOSTON — Long-term results from two phase 3 trials of tenofovir disoproxil fumarate for chronic hepatitis B demonstrated safety and efficacy of the treatment with no resistance through 8 years, according to data presented at a plenary session during The Liver Meeting.
“Tenofovir disoproxil fumarate is a potent first-line treatment for patients with chronic hepatitis B,” Maria Buti, MD, of Vall d'Hebron University Hospital in Barcelona, Spain, said in a presentation. “Here we present efficacy, safety and resistance results over 8 years of tenofovir disoproxil fumarate treatment.”
Continuing the extension phase of two phase 3 studies whose data through year 5 was reported previously, Buti and colleagues evaluated the remaining 412 patients (64% of the original cohort). Patients had hepatitis B e antigen (HBeAg)-negative (n=266) and HBeAg-positive (n=146) chronic hepatitis B and continued on open label Tenofovir disoproxil fumarate (TDF) through year 8 after an initial 48-week comparative study of TDF and adefovir dipivoxil. The researchers evaluated these patients for treatment safety and efficacy every 3 months, tested them for resistance once a year, and began testing bone mineral density once a year starting at year 4.
Eight-year results showed that durable viral suppression was maintained, seven additional patients had loss of HBsAG beginning in year 5 and no resistance to TDF was detected throughout the study period. Overall response was observed in 75% of HBeAg-negative patients, and 58% of HBeAg-positive patients. Confirmed renal events, including increase in serum creatinine (at least 0.5 mg) or serum phosphorous (less than 2 mg/dL), or creatinine clearance (less than 50mL/min) occurred in 2.2% of patients, and bone mineral density scores of the hip and spine remained stable from year 4 to 8.
“Over an 8 year treatment period with tenofovir disoproxil fumarate, virological and serological responses were durable,…virological suppression was consistently maintained in almost all the patients…and no TDF resistance was detected through 8 years,” Buti said. “Long-term TDF treatment was well tolerated, renal events were uncommon… and no clinically relevant bone loss was observed between year 4 and year 8.”
For more information:
Marcellin P. Abstract 229. Presented at: The Liver Meeting, Nov. 7-11, 2014; Boston, MA.
Disclosure: See the abstract for a full list of relevant financial disclosures.