— Christine M. Kukka, Project Manager, HBV Advocate
In the first study of its kind, Japanese researchers reported that a
51-year-old woman has developed drug resistance to the antiviral
tenofovir (Viread.) This is the first reported case of drug resistance
linked to tenofovir.
Tenofovir currently leads the list of "go to" antiviral drugs to
treat hepatitis B. Numerous studies have shown that tenofovir causes no
resistance, even after more than five years of treatment.
However, in this report published in the June issue of the journal of Drug Design, Development and Therapy,
researchers reported that a woman with HBV genotype C who had developed
resistance to the antiviral entecavir (Baraclude) months earlier also
developed resistance to tenofovir.
For many months, she had been treated with just
entecavir but when her viral load began to rise, doctors added
tenofovir to her ongoing entecavir treatment. Her viral load decreased
to less than 1,000 international units per milliliter (IU/mL) over 31
months while on the entecavir-tenofovir combination, but then it began
to rise again.
When researchers examined the genetic make-up of
her HBV, they found that it had mutated after the tenofovir was added.
"Long-term therapy with tenofovir against the entecavir-resistant (HBV)
has the potential to induce virologic breakthrough and resistance, and
careful follow-up should be carried out," they wrote.
www.ncbi.nlm.nih.gov/pubmed/25061278
Source: HBV Journal Review: August 1, 2014, Vol 11, no 8 Labels: tenofovir resistance